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Recommendations on the Use of Ultrasound Guidance for Central and Peripheral Vascular Access in Adults: A Position Statement of the Society of Hospital Medicine
Approximately five million central venous catheters (CVCs) are inserted in the United States annually, with over 15 million catheter days documented in intensive care units alone.1 Traditional CVC insertion techniques using landmarks are associated with a high risk of mechanical complications, particularly pneumothorax and arterial puncture, which occur in 5%-19% patients.2,3
Since the 1990s, several randomized controlled studies and meta-analyses have demonstrated that the use of real-time ultrasound guidance for CVC insertion increases procedure success rates and decreases mechanical complications.4,5 Use of real-time ultrasound guidance was recommended by the Agency for Healthcare Research and Quality, the Institute of Medicine, the National Institute for Health and Care Excellence, the Centers for Disease Control and Prevention, and several medical specialty societies in the early 2000s.6-14 Despite these recommendations, ultrasound guidance has not been universally adopted. Currently, an estimated 20%-55% of CVC insertions in the internal jugular vein are performed without ultrasound guidance.15-17
Following the emergence of literature supporting the use of ultrasound guidance for CVC insertion, observational and randomized controlled studies demonstrated improved procedural success rates with the use of ultrasound guidance for the insertion of peripheral intravenous lines (PIVs), arterial catheters, and peripherally inserted central catheters (PICCs).18-23
The purpose of this position statement is to present evidence-based recommendations on the use of ultrasound guidance for the insertion of central and peripheral vascular access catheters in adult patients. This document presents consensus-based recommendations with supporting evidence for clinical outcomes, techniques, and training for the use of ultrasound guidance for vascular access. We have subdivided the recommendations on techniques for central venous access, peripheral venous access, and arterial access individually, as some providers may not perform all types of vascular access procedures.
These recommendations are intended for hospitalists and other healthcare providers that routinely place central and peripheral vascular access catheters in acutely ill patients. However, this position statement does not mandate that all hospitalists should place central or peripheral vascular access catheters given the diverse array of hospitalist practice settings. For training and competency assessments, we recognize that some of these recommendations may not be feasible in resource-limited settings, such as rural hospitals, where equipment and staffing for assessments are not available. Recommendations and frameworks for initial and ongoing credentialing of hospitalists in ultrasound-guided bedside procedures have been previously published in an Society of Hospital Medicine (SHM) position statement titled, “Credentialing of Hospitalists in Ultrasound-Guided Bedside Procedures.”24
METHODS
Detailed methods are described in Appendix 1. The SHM Point-of-care Ultrasound (POCUS) Task Force was assembled to carry out this guideline development project under the direction of the SHM Board of Directors, Director of Education, and Education Committee. All expert panel members were physicians or advanced practice providers with expertise in POCUS. Expert panel members were divided into working group members, external peer reviewers, and a methodologist. All Task Force members were required to disclose any potential conflicts of interest (Appendix 2). The literature search was conducted in two independent phases. The first phase included literature searches conducted by the vascular access working group members themselves. Key clinical questions and draft recommendations were then prepared. A systematic literature search was conducted by a medical librarian based on the findings of the initial literature search and draft recommendations. The Medline, Embase, CINAHL, and Cochrane medical databases were searched from 1975 to December 2015 initially. Google Scholar was also searched without limiters. An updated search was conducted in November 2017. The literature search strings are included in Appendix 3. All article abstracts were initially screened for relevance by at least two members of the vascular access working group. Full-text versions of screened articles were reviewed, and articles on the use of ultrasound to guide vascular access were selected. The following article types were excluded: non-English language, nonhuman, age <18 years, meeting abstracts, meeting posters, narrative reviews, case reports, letters, and editorials. All relevant systematic reviews, meta-analyses, randomized controlled studies, and observational studies of ultrasound-guided vascular access were screened and selected (Appendix 3, Figure 1). All full-text articles were shared electronically among the working group members, and final article selection was based on working group consensus. Selected articles were incorporated into the draft recommendations.
These recommendations were developed using the Research and Development (RAND) Appropriateness Method that required panel judgment and consensus.14 The 28 voting members of the SHM POCUS Task Force reviewed and voted on the draft recommendations considering five transforming factors: (1) Problem priority and importance, (2) Level of quality of evidence, (3) Benefit/harm balance, (4) Benefit/burden balance, and (5) Certainty/concerns about PEAF (Preferences/Equity/Acceptability/Feasibility). Using an internet-based electronic data collection tool (REDCap™), panel members participated in two rounds of electronic voting, one in August 2018 and the other in October 2018 (Appendix 4). Voting on appropriateness was conducted using a nine-point Likert scale. The three zones of the nine-point Likert scale were inappropriate (1-3 points), uncertain (4-6 points), and appropriate (7-9 points). The degree of consensus was assessed using the RAND algorithm (Appendix 1, Figure 1 and Table 1). Establishing a recommendation required at least 70% agreement that a recommendation was “appropriate.” Disagreement was defined as >30% of panelists voting outside of the zone of the median. A strong recommendation required at least 80% of the votes within one integer of the median per the RAND rules.
Recommendations were classified as strong or weak/conditional based on preset rules defining the panel’s level of consensus, which determined the wording for each recommendation (Table 2). The final version of the consensus-based recommendations underwent internal and external review by members of the SHM POCUS Task Force, the SHM Education Committee, and the SHM Executive Committee. The SHM Executive Committee reviewed and approved this position statement prior to its publication in the Journal of Hospital Medicine.
RESULTS
Literature Search
A total of 5,563 references were pooled from an initial search performed by a certified medical librarian in December 2015 (4,668 citations) which was updated in November 2017 (791 citations), and from the personal bibliographies and searches (104 citations) performed by working group members. A total of 514 full-text articles were reviewed. The final selection included 192 articles that were abstracted into a data table and incorporated into the draft recommendations. See Appendix 3 for details of the literature search strategy.
Recommendations
Four domains (technique, clinical outcomes, training, and knowledge gaps) with 31 draft recommendations were generated based on a review of the literature. Selected references were abstracted and assigned to each draft recommendation. Rationales for each recommendation cite supporting evidence. After two rounds of panel voting, 31 recommendations achieved agreement based on the RAND rules. During the peer review process, two of the recommendations were merged with other recommendations. Thus, a total of 29 recommendations received final approval. The degree of consensus based on the median score and the dispersion of voting around the median are shown in Appendix 5. Twenty-seven statements were approved as strong recommendations, and two were approved as weak/conditional recommendations. The strength of each recommendation and degree of consensus are summarized in Table 3.
Terminology
Central Venous Catheterization
Central venous catheterization refers to insertion of tunneled or nontunneled large bore vascular catheters that are most commonly inserted into the internal jugular, subclavian, or femoral veins with the catheter tip located in a central vein. These vascular access catheters are synonymously referred to as central lines or central venous catheters (CVCs). Nontunneled catheters are designed for short-term use and should be removed promptly when no longer clinically indicated or after a maximum of 14 days.25
Peripherally Inserted Central Catheter (PICC)
Peripherally inserted central catheters, or PICC lines, are inserted most commonly in the basilic or brachial veins in adult patients, and the catheter tip terminates in the distal superior vena cava or cavo-atrial junction. These catheters are designed to remain in place for a duration of several weeks, as long as it is clinically indicated.
Midline Catheterization
Midline catheters are a type of peripheral venous catheter that are an intermediary between a peripheral intravenous catheter and PICC line. Midline catheters are most commonly inserted in the brachial or basilic veins, but unlike PICC lines, the tips of these catheters terminate in the axillary or subclavian vein. Midline catheters are typically 8 cm to 20 cm in length and inserted for a duration <30 days.
Peripheral Intravenous Catheterization
Peripheral intravenous lines (PIV) refer to small bore venous catheters that are most commonly 14G to 24G and inserted into patients for short-term peripheral venous access. Common sites of ultrasound-guided PIV insertion include the superficial and deep veins of the hand, forearm, and arm.
Arterial Catheterization
Arterial catheters are commonly used for reliable blood pressure monitoring, frequent arterial blood
RECOMMENDATIONS
Preprocedure
1. We recommend that providers should be familiar with the operation of their specific ultrasound machine prior to initiation of a vascular access procedure.
Rationale: There is strong consensus that providers must be familiar with the knobs and functions of the specific make and model of ultrasound machine that will be utilized for a vascular access procedure. Minimizing adjustments to the ultrasound machine during the procedure may reduce the risk of contaminating the sterile field.
2. We recommend that providers should use a high-frequency linear transducer with a sterile sheath and sterile gel to perform vascular access procedures.
Rationale: High-frequency linear-array transducers are recommended for the vast majority of vascular access procedures due to their superior resolution compared to other transducer types. Both central and peripheral vascular access procedures, including PIV, PICC, and arterial line placement, should be performed using sterile technique. A sterile transducer cover and sterile gel must be utilized, and providers must be trained in sterile preparation of the ultrasound transducer.13,26,27
The depth of femoral vessels correlates with body mass index (BMI). When accessing these vessels in a morbidly obese patient with a thigh circumference >60 cm and vessel depth >8 cm, a curvilinear transducer may be preferred for its deeper penetration.28 For patients who are poor candidates for bedside insertion of vascular access catheters, such as uncooperative patients, patients with atypical vascular anatomy or poorly visualized target vessels, we recommend consultation with a vascular access specialist prior to attempting the procedure.
3. We recommend that providers should use two-dimensional ultrasound to evaluate for anatomical variations and absence of vascular thrombosis during preprocedural site selection.
Rationale: A thorough ultrasound examination of the target vessel is warranted prior to catheter placement. Anatomical variations that may affect procedural decision-making are easily detected with ultrasound. A focused vascular ultrasound examination is particularly important in patients who have had temporary or tunneled venous catheters, which can cause stenosis or thrombosis of the target vein.
For internal jugular vein (IJV) CVCs, ultrasound is useful for visualizing the relationship between the IJV and common carotid artery (CCA), particularly in terms of vessel overlap. Furthermore, ultrasound allows for immediate revisualization upon changes in head position.29-32 Troianos et al. found >75% overlap of the IJV and CCA in 54% of all patients and in 64% of older patients (age >60 years) whose heads were rotated to the contralateral side.30 In one study of IJV CVC insertion, inadvertent carotid artery punctures were reduced (3% vs 10%) with the use of ultrasound guidance vs landmarks alone.33 In a cohort of 64 high-risk neurosurgical patients, cannulation success was 100% with the use of ultrasound guidance, and there were no injuries to the carotid artery, even though the procedure was performed with a 30-degree head elevation and anomalous IJV anatomy in 39% of patients.34 In a prospective, randomized controlled study of 1,332 patients, ultrasound-guided cannulation in a neutral position was demonstrated to be as safe as the 45-degree rotated position.35
Ultrasound allows for the recognition of anatomical variations which may influence the selection of the vascular access site or technique. Benter et al. found that 36% of patients showed anatomical variations in the IJV and surrounding tissue.36 Similarly Caridi showed the anatomy of the right IJV to be atypical in 29% of patients,37 and Brusasco found that 37% of bariatric patients had anatomical variations of the IJV.38 In a study of 58 patients, there was significant variability in the IJV position and IJV diameter, ranging from 0.5 cm to >2 cm.39 In a study of hemodialysis patients, 75% of patients had sonographic venous abnormalities that led to a change in venous access approach.40
To detect acute or chronic upper extremity deep venous thrombosis or stenosis, two-dimensional visualization with compression should be part of the ultrasound examination prior to central venous catheterization. In a study of patients that had undergone CVC insertion 9-19 weeks earlier, 50% of patients had an IJV thrombosis or stenosis leading to selection of an alternative site. In this study, use of ultrasound for a preprocedural site evaluation reduced unnecessary attempts at catheterizing an occluded vein.41 At least two other studies demonstrated an appreciable likelihood of thrombosis. In a study of bariatric patients, 8% of patients had asymptomatic thrombosis38 and in another study, 9% of patients being evaluated for hemodialysis catheter placement had asymptomatic IJV thrombosis.37
4. We recommend that providers should evaluate the target blood vessel size and depth during a preprocedural ultrasound evaluation.
Rationale: The size, depth, and anatomic location of central veins can vary considerably. These features are easily discernable using ultrasound. Contrary to traditional teaching, the IJV is located 1 cm anterolateral to the CCA in only about two-thirds of patients.37,39,42,43 Furthermore, the diameter of the IJV can vary significantly, ranging from 0.5 cm to >2 cm.39 The laterality of blood vessels may vary considerably as well. A preprocedural ultrasound evaluation of contralateral subclavian and axillary veins showed a significant absolute difference in cross-sectional area of 26.7 mm2 (P < .001).42
Blood vessels can also shift considerably when a patient is in the Trendelenburg position. In one study, the IJV diameter changed from 11.2 (± 1.5) mm to 15.4 (± 1.5) mm in the supine versus the Trendelenburg position at 15 degrees.33 An observational study demonstrated a frog-legged position with reverse Trendelenburg increased the femoral vein size and reduced the common surface area with the common femoral artery compared to a neutral position. Thus, a frog-legged position with reverse Trendelenburg position may be preferred, since overall catheterization success rates are higher in this position.44
Techniques
General Techniques
5. We recommend that providers should avoid using static ultrasound alone to mark the needle insertion site for vascular access procedures.
Rationale: The use of static ultrasound guidance to mark a needle insertion site is not recommended because normal anatomical relationships of vessels vary, and site marking can be inaccurate with minimal changes in patient position, especially of the neck.43,45,46 Benefits of using ultrasound guidance for vascular access are attained when ultrasound is used to track the needle tip in real-time as it is advanced toward the target vessel.
Although continuous-wave Doppler ultrasound without two-dimensional visualization was used in the past, it is no longer recommended for IJV CVC insertion.47 In a study that randomized patients to IJV CVC insertion with continuous-wave Doppler alone vs two-dimensional ultrasound guidance, the use of two-dimensional ultrasound guidance showed significant improvement in first-pass success rates (97% vs 91%, P = .045), particularly in patients with BMI >30 (97% vs 77%, P = .011).48
A randomized study comparing real-time ultrasound-guided, landmark-based, and ultrasound-marked techniques found higher success rates in the real-time ultrasound-guided group than the other two groups (100% vs 74% vs 73%, respectively; P = .01). The total number of mechanical complications was higher in the landmark-based and ultrasound-marked groups than in the real-time ultrasound-guided group (24% and 36% versus 0%, respectively; P = .01).49 Another randomized controlled study found higher success rates with real-time ultrasound guidance (98%) versus an ultrasound-marked (82%) or landmark-based (64%) approach for central line placement.50
6. We recommend that providers should use real-time (dynamic), two-dimensional ultrasound guidance with a high-frequency linear transducer for CVC insertion, regardless of the provider’s level of experience.
7. We suggest using either a transverse (short-axis) or longitudinal (long-axis) approach when performing real-time ultrasound-guided vascular access procedures.
Rationale: In clinical practice, the phrases transverse, short-axis, or out-of-plane approach are synonymous, as are longitudinal, long-axis, and in-plane approach. The short-axis approach involves tracking the needle tip as it approximates the target vessel with the ultrasound beam oriented in a transverse plane perpendicular to the target vessel. The target vessel is seen as a circular structure on the ultrasound screen as the needle tip approaches the target vessel from above. This approach is also called the out-of-plane technique since the needle passes through the ultrasound plane. The advantages of the short-axis approach include better visualization of adjacent vessels or nerves and the relative ease of skill acquisition for novice operators.9 When using the short-axis approach, extra care must be taken to track the needle tip from the point of insertion on the skin to the target vessel. A disadvantage of the short-axis approach is unintended posterior wall puncture of the target vessel.55
In contrast to a short-axis approach, a long-axis approach is performed with the ultrasound beam aligned parallel to the vessel. The vessel appears as a long tubular structure and the entire needle is visualized as it traverses across the ultrasound screen to approach the target vessel. The long-axis approach is also called an in-plane technique because the needle is maintained within the plane of the ultrasound beam. The advantage of a long-axis approach is the ability to visualize the entire needle as it is inserted into the vessel.14 A randomized crossover study with simulation models compared a long-axis versus short-axis approach for both IJV and subclavian vein catheterization. This study showed decreased number of needle redirections (relative risk (RR) 0.5, 95% confidence interval (CI) 0.3 to 0.7), and posterior wall penetrations (OR 0.3, 95% CI 0.1 to 0.9) using a long-axis versus short-axis approach for subclavian vein catheterization.56
A randomized controlled study comparing a long-axis or short-axis approach with ultrasound versus a landmark-based approach for IJV CVC insertion showed higher success rates (100% vs 90%; P < .001), lower insertion time (53 vs 116 seconds; P < .001), and fewer attempts to obtain access (2.5 vs 1.2 attempts, P < .001) with either the long- or short-axis ultrasound approach. The average time to obtain access and number of attempts were comparable between the short-axis and long-axis approaches with ultrasound. The incidence of carotid puncture and hematoma was significantly higher with the landmark-based approach versus either the long- or short-axis ultrasound approach (carotid puncture 17% vs 3%, P = .024; hematoma 23% vs 3%, P = .003).57
High success rates have been reported using a short-axis approach for insertion of PIV lines.58 A prospective, randomized trial compared the short-axis and long-axis approach in patients who had had ≥2 failed PIV insertion attempts. Success rate was 95% (95% CI, 0.85 to 1.00) in the short-axis group compared with 85% (95% CI, 0.69 to 1.00) in the long-axis group. All three subjects with failed PIV placement in the long-axis group had successful rescue placement using a short-axis approach. Furthermore, the short-axis approach was faster than the long-axis approach.59
For radial artery cannulation, limited data exist comparing the short- and long-axis approaches. A randomized controlled study compared a long-axis vs short-axis ultrasound approach for radial artery cannulation. Although the overall procedure success rate was 100% in both groups, the long-axis approach had higher first-pass success rates (1.27 ± 0.4 vs 1.5 ± 0.5, P < .05), shorter cannulation times (24 ± 17 vs 47 ± 34 seconds, P < .05), fewer hematomas (4% vs 43%, P < .05) and fewer posterior wall penetrations (20% vs 56%, P < .05).60
Another technique that has been described for IJV CVC insertion is an oblique-axis approach, a hybrid between the long- and short-axis approaches. In this approach, the transducer is aligned obliquely over the IJV and the needle is inserted using a long-axis or in-plane approach. A prospective randomized trial compared the short-axis, long-axis, and oblique-axis approaches during IJV cannulation. First-pass success rates were 70%, 52%, and 74% with the short-axis, long-axis, and oblique-axis approaches, respectively, and a statistically significant difference was found between the long- and oblique-axis approaches (P = .002). A higher rate of posterior wall puncture was observed with a short-axis approach (15%) compared with the oblique-axis (7%) and long-axis (4%) approaches (P = .047).61
8. We recommend that providers should visualize the needle tip and guidewire in the target vein prior to vessel dilatation.
Rationale: When real-time ultrasound guidance is used, visualization of the needle tip within the vein is the first step to confirm cannulation of the vein and not the artery. After the guidewire is advanced, the provider can use transverse and longitudinal views to reconfirm cannulation of the vein. In a longitudinal view, the guidewire is readily seen positioned within the vein, entering the anterior wall and lying along the posterior wall of the vein. Unintentional perforation of the posterior wall of the vein with entry into the underlying artery can be detected by ultrasound, allowing prompt removal of the needle and guidewire before proceeding with dilation of the vessel. In a prospective observational study that reviewed ultrasound-guided IJV CVC insertions, physicians were able to more readily visualize the guidewire than the needle in the vein.62 A prospective observational study determined that novice operators can visualize intravascular guidewires in simulation models with an overall accuracy of 97%.63
In a retrospective review of CVC insertions where the guidewire position was routinely confirmed in the target vessel prior to dilation, there were no cases of arterial dilation, suggesting confirmation of guidewire position can potentially eliminate the morbidity and mortality associated with arterial dilation during CVC insertion.64
9. To increase the success rate of ultrasound-guided vascular access procedures, we recommend that providers should utilize echogenic needles, plastic needle guides, and/or ultrasound beam steering when available.
Rationale: Echogenic needles have ridged tips that appear brighter on the screen, allowing for better visualization of the needle tip. Plastic needle guides help stabilize the needle alongside the transducer when using either a transverse or longitudinal approach. Although evidence is limited, some studies have reported higher procedural success rates when using echogenic needles, plastic needle guides, and ultrasound beam steering software. In a prospective observational study, Augustides et al. showed significantly higher IJV cannulation rates with versus without use of a needle guide after first (81% vs 69%, P = .0054) and second (93% vs 80%. P = .0001) needle passes.65 A randomized study by Maecken et al. compared subclavian vein CVC insertion with or without use of a needle guide, and found higher procedure success rates within the first and second attempts, reduced time to obtain access (16 seconds vs 30 seconds; P = .0001) and increased needle visibility (86% vs 32%; P < .0001) with the use of a needle guide.66 Another study comparing a short-axis versus long-axis approach with a needle guide showed improved needle visualization using a long-axis approach with a needle guide.67 A randomized study comparing use of a novel, sled-mounted needle guide to a free-hand approach for venous cannulation in simulation models showed the novel, sled-mounted needle guide improved overall success rates and efficiency of cannulation.68
Central Venous Access Techniques
10. We recommend that providers should use a standardized procedure checklist that includes use of real-time ultrasound guidance to reduce the risk of central line-associated bloodstream infection (CLABSI) from CVC insertion.
Rationale: A standardized checklist or protocol should be developed to ensure compliance with all recommendations for insertion of CVCs. Evidence-based protocols address periprocedural issues, such as indications for CVC, and procedural techniques, such as use of maximal sterile barrier precautions to reduce the risk of infection. Protocols and checklists that follow established guidelines for CVC insertion have been shown to decrease CLABSI rates.69,70 Similarly, development of checklists and protocols for maintenance of central venous catheters have been effective in reducing CLABSIs.71 Although no externally-validated checklist has been universally accepted or endorsed by national safety organizations, a few internally-validated checklists are available through peer-reviewed publications.72,73 An observational educational cohort of internal medicine residents who received training using simulation of the entire CVC insertion process was able to demonstrate fewer CLABSIs after the simulator-trained residents rotated in the intensive care unit (ICU) (0.50 vs 3.2 infections per 1,000 catheter days, P = .001).74
11. We recommend that providers should use real-time ultrasound guidance, combined with aseptic technique and maximal sterile barrier precautions, to reduce the incidence of infectious complications from CVC insertion.
Rationale: The use of real-time ultrasound guidance for CVC placement has demonstrated a statistically significant reduction in CLABSIs compared to landmark-based techniques.75 The Centers for Disease Control and Prevention (CDC) guidelines for the prevention of intravascular catheter-related infections recommend the use of ultrasound guidance to reduce the number of cannulation attempts and risk of mechanical complications.69 A prospective, three-arm study comparing ultrasound-guided long-axis, short-axis, and landmark-based approaches showed a CLABSI rate of 20% in the landmark-based group versus 10% in each of the ultrasound groups.57 Another randomized study comparing use of ultrasound guidance to a landmark-based technique for IJV CVC insertion demonstrated significantly lower CLABSI rates with the use of ultrasound (2% vs 10%; P < .05).72
Studies have shown that a systems-based intervention featuring a standardized catheter kit or catheter bundle significantly reduced CLABSI rates.76-78 A complete review of all preventive measures to reduce the risk of CLABSI is beyond the scope of this review, but a few key points will be mentioned. First, aseptic technique includes proper hand hygiene and skin sterilization, which are essential measures to reduce cutaneous colonization of the insertion site and reduce the risk of CLABSIs.79 In a systematic review and meta-analysis of eight studies including over 4,000 catheter insertions, skin antisepsis with chlorhexidine was associated with a 50% reduction in CLABSIs compared with povidone iodine.11 Therefore, a chlorhexidine-containing solution is recommended for skin preparation prior to CVC insertion per guidelines by Healthcare Infection Control Practices Advisory Committee/CDC, Society for Healthcare Epidemiology of America/Infectious Diseases Society of America, and American Society of Anesthesiologists.11,69,80,81 Second, maximal sterile barrier precautions refer to the use of sterile gowns, sterile gloves, caps, masks covering both the mouth and nose, and sterile full-body patient drapes. Use of maximal sterile barrier precautions during CVC insertion has been shown to reduce the incidence of CLABSIs compared to standard precautions.26,79,82-84 Third, catheters containing antimicrobial agents may be considered for hospital units with higher CLABSI rates than institutional goals, despite a comprehensive preventive strategy, and may be considered in specific patient populations at high risk of severe complications from a CLABSI.11,69,80 Finally, providers should use a standardized procedure set-up when inserting CVCs to reduce the risk of CLABSIs. The operator should confirm availability and proper functioning of ultrasound equipment prior to commencing a vascular access procedure. Use of all-inclusive procedure carts or kits with sterile ultrasound probe covers, sterile gel, catheter kits, and other necessary supplies is recommended to minimize interruptions during the procedure, and can ultimately reduce the risk of CLABSIs by ensuring maintenance of a sterile field during the procedure.13
12. We recommend that providers should use real-time ultrasound guidance for internal jugular vein catheterization, which reduces the risk of mechanical and infectious complications, the number of needle passes, and time to cannulation and increases overall procedure success rates.
Rationale: The use of real-time ultrasound guidance for CVC insertion has repeatedly demonstrated better outcomes compared to a landmark-based approach in adults.13 Several randomized controlled studies have demonstrated that real-time ultrasound guidance for IJV cannulation reduces the risk of procedure-related mechanical and infectious complications, and improves first-pass and overall success rates in diverse care settings.27,29,45,50,53,65,75,85-90 Mechanical complications that are reduced with ultrasound guidance include pneumothorax and carotid artery puncture.4,5,45,46,53,62,75,86-93 Currently, several medical societies strongly recommend the use of ultrasound guidance during insertion of IJV CVCs.10-12,14,94-96
A meta-analysis by Hind et al. that included 18 randomized controlled studies demonstrated use of real-time ultrasound guidance reduced failure rates (RR 0.14, 95% CI 0.06 to 0.33; P < .0001), increased first-attempt success rates (RR 0.59, 95% CI 0.39 to 0.88; P = .009), reduced complication rates (RR 0.43, 95% CI 0.22 to 0.87; P = .02) and reduced procedure time (P < .0001), compared to a traditional landmark-based approach when inserting IJV CVCs.5
A Cochrane systematic review compared ultrasound-guided versus landmark-based approaches for IJV CVC insertion and found use of real-time ultrasound guidance reduced total complication rates by 71% (RR 0.29, 95% CI 0.17 to 0.52; P < .0001), arterial puncture rates by 72% (RR 0.28, 95% CI 0.18 to 0.44; P < .00001), and rates of hematoma formation by 73% (RR 0.27, 95% CI 0.13 to 0.55; P = .0004). Furthermore, the number of attempts for successful cannulation was reduced (mean difference -1.19 attempts, 95% CI -1.45 to -0.92; P < .00001), the chance of successful insertion on the first attempt was increased by 57% (RR 1.57, 95% CI 1.36 to 1.82; P < .00001), and overall procedure success rates were modestly increased in all groups by 12% (RR 1.12, 95% CI 1.08 to 1.17; P < .00001).46
An important consideration in performing ultrasound guidance is provider experience. A prospective observational study of patients undergoing elective CVC insertion demonstrated higher complication rates for operators that were inexperienced (25.2%) versus experienced (13.6%).54 A randomized controlled study comparing experts and novices with or without the use of ultrasound guidance for IJV CVC insertion demonstrated higher success rates among expert operators and with the use of ultrasound guidance. Among novice operators, the complication rates were lower with the use of ultrasound guidance.97 One study evaluated the procedural success and complication rates of a two-physician technique with one physician manipulating the transducer and another inserting the needle for IJV CVC insertion. This study concluded that procedural success rates and frequency of complications were directly affected by the experience of the physician manipulating the transducer and not by the experience of the physician inserting the needle.98
The impact of ultrasound guidance on improving procedural success rates and reducing complication rates is greatest in patients that are obese, short necked, hypovolemic, or uncooperative.93 Several studies have demonstrated fewer needle passes and decreased time to cannulation compared to the landmark technique in these populations.46,49,53,86-88,92,93
Ultrasound-guided placement of IJV catheters can safely be performed in patients with disorders of hemostasis and those with multiple previous catheter insertions in the same vein.9 Ultrasound-guided placement of CVCs in patients with disorders of hemostasis is safe with high success and low complication rates. In a case series of liver patients with coagulopathy (mean INR 2.17 ± 1.16, median platelet count 150K), the use of ultrasound guidance for CVC insertion was highly successful with no major bleeding complications.99
A study of renal failure patients found high success rates and low complication rates in the patients with a history of multiple previous catheterizations, poor compliance, skeletal deformities, previous failed cannulations, morbid obesity, and disorders of hemostasis.100 A prospective observational study of 200 ultrasound-guided CVC insertions for apheresis showed a 100% success rate with a 92% first-pass success rate.101
The use of real-time ultrasound guidance for IJV CVC insertion has been shown to be cost effective by reducing procedure-related mechanical complications and improving procedural success rates. A companion cost-effectiveness analysis estimated that for every 1,000 patients, 90 complications would be avoided, with a net cost savings of approximately $3,200 using 2002 prices.102
13. We recommend that providers who routinely insert subclavian vein CVCs should use real-time ultrasound guidance, which has been shown to reduce the risk of mechanical complications and number of needle passes and increase overall procedure success rates compared with landmark-based techniques.
Rationale: In clinical practice, the term ultrasound-guided subclavian vein CVC insertion is commonly used. However, the needle insertion site is often lateral to the first rib and providers are technically inserting the CVC in the axillary vein. The subclavian vein becomes the axillary vein at the lateral border of the first rib where the cephalic vein branches from the subclavian vein. To be consistent with common medical parlance, we use the phrase ultrasound-guided subclavian vein CVC insertion in this document.
Advantages of inserting CVCs in the subclavian vein include reliable surface anatomical landmarks for vein location, patient comfort, and lower risk of infection.103 Several observational studies have demonstrated the technique for ultrasound-guided subclavian vein CVC insertion is feasible and safe.104-107 In a large retrospective observational study of ultrasound-guided central venous access among a complex patient group, the majority of patients were cannulated successfully and safely. The subset of patients undergoing axillary vein CVC insertion (n = 1,923) demonstrated a low rate of complications (0.7%), proving it is a safe and effective alternative to the IJV CVC insertion.107
A Cochrane review of ultrasound-guided subclavian vein cannulation (nine studies, 2,030 participants, 2,049 procedures), demonstrated that real-time two-dimensional ultrasound guidance reduced the risk of inadvertent arterial punctures (three studies, 498 participants, RR 0.21, 95% CI 0.06 to 0.82; P = .02) and hematoma formation (three studies, 498 participants, RR 0.26, 95% CI 0.09 to 0.76; P = .01).46 A systematic review and meta-analysis of 10 randomized controlled studies comparing ultrasound-guided versus landmark-based subclavian vein CVC insertion demonstrated a reduction in the risk of arterial punctures, hematoma formation, pneumothorax, and failed catheterization with the use of ultrasound guidance.105
A randomized controlled study comparing ultrasound-guided vs landmark-based approaches to subclavian vein cannulation found that use of ultrasound guidance had a higher success rate (92% vs 44%, P = .0003), fewer minor complications (1 vs 11, P = .002), fewer attempts (1.4 vs 2.5, P = .007) and fewer catheter kits used (1.0 vs 1.4, P = .0003) per cannulation.108
Fragou et al. randomized patients undergoing subclavian vein CVC insertion to a long-axis approach versus a landmark-based approach and found a significantly higher success rate (100% vs 87.5%, P < .05) and lower rates of mechanical complications: artery puncture (0.5% vs 5.4%), hematoma (1.5% vs 5.4%), hemothorax (0% vs 4.4%), pneumothorax (0% vs 4.9%), brachial plexus injury (0% vs 2.9%), phrenic nerve injury (0% vs 1.5%), and cardiac tamponade (0% vs 0.5%).109 The average time to obtain access and the average number of insertion attempts (1.1 ± 0.3 vs 1.9 ± 0.7, P < .05) were significantly reduced in the ultrasound group compared to the landmark-based group.95
A retrospective review of subclavian vein CVC insertions using a supraclavicular approach found no reported complications with the use of ultrasound guidance vs 23 mechanical complications (8 pneumothorax, 15 arterial punctures) with a landmark-based approach.106 However, it is important to note that a supraclavicular approach is not commonly used in clinical practice.
14. We recommend that providers should use real-time ultrasound guidance for femoral venous access, which has been shown to reduce the risk of arterial punctures and total procedure time and increase overall procedure success rates.
Rationale: Anatomy of the femoral region varies, and close proximity or overlap of the femoral vein and artery is common.51 Early studies showed that ultrasound guidance for femoral vein CVC insertion reduced arterial punctures compared with a landmark-based approach (7% vs 16%), reduced total procedure time (55 ± 19 vs 79 ± 62 seconds), and increased procedure success rates (100% vs 90%).52 A Cochrane review that pooled data from four randomized studies comparing ultrasound-guided vs landmark-based femoral vein CVC insertion found higher first-attempt success rates with the use of ultrasound guidance (RR 1.73, 95% CI 1.34 to 2.22; P < .0001) and a small increase in the overall procedure success rates (RR 1.11, 95% CI 1.00 to 1.23; P = .06). There was no difference in inadvertent arterial punctures or other complications.110
Peripheral Venous Access Techniques
15. We recommend that providers should use real-time ultrasound guidance for the insertion of peripherally inserted central catheters (PICCs), which is associated with higher procedure success rates and may be more cost effective compared with landmark-based techniques.
Rationale: Several studies have demonstrated that providers who use ultrasound guidance vs landmarks for PICC insertion have higher procedural success rates, lower complication rates, and lower total placement costs. A prospective observational report of 350 PICC insertions using ultrasound guidance reported a 99% success rate with an average of 1.2 punctures per insertion and lower total costs.20 A retrospective observational study of 500 PICC insertions by designated specialty nurses revealed an overall success rate of 95%, no evidence of phlebitis, and only one CLABSI among the catheters removed.21 A retrospective observational study comparing several PICC variables found higher success rates (99% vs 77%) and lower thrombosis rates (2% vs 9%) using ultrasound guidance vs landmarks alone.22 A study by Robinson et al. demonstrated that having a dedicated PICC team equipped with ultrasound increased their institutional insertion success rates from 73% to 94%.111
A randomized controlled study comparing ultrasound-guided versus landmark-based PICC insertion found high success rates with both techniques (100% vs 96%). However, there was a reduction in the rate of unplanned catheter removals (4.0% vs 18.7%; P = .02), mechanical phlebitis (0% vs 22.9%; P < .001), and venous thrombosis (0% vs 8.3%; P = .037), but a higher rate of catheter migration (32% vs 2.1%; P < .001). Compared with the landmark-based group, the ultrasound-guided group had significantly lower incidence of severe contact dermatitis (P = .038), and improved comfort and costs up to 3 months after PICC placement (P < .05).112
Routine postprocedure chest x-ray (CXR) is generally considered unnecessary if the PICC is inserted with real-time ultrasound guidance along with use of a newer tracking devices, like the magnetic navigation system with intracardiac electrodes.9 Ultrasound can also be used to detect malpositioning of a PICC immediately after completing the procedure. A randomized controlled study comparing ultrasound versus postprocedure CXR detected one malpositioned PICC in the ultrasound group versus 11 in the control group. This study suggested that ultrasound can detect malpositioning immediately postprocedure and reduce the need for a CXR and the possibility of an additional procedure to reposition a catheter.113
16. We recommend that providers should use real-time ultrasound guidance for the placement of peripheral intravenous lines (PIV) in patients with difficult peripheral venous access to reduce the total procedure time, needle insertion attempts, and needle redirections. Ultrasound-guided PIV insertion is also an effective alternative to CVC insertion in patients with difficult venous access.
Rationale: Difficult venous access refers to patients that have had two unsuccessful attempts at PIV insertion using landmarks or a history of difficult access (i.e. edema, obesity, intravenous drug use, chemotherapy, diabetes, hypovolemia, chronic illness, vasculopathy, multiple prior hospitalizations). A meta-analysis of seven randomized controlled studies concluded that ultrasound guidance increases the likelihood of successful PIV insertion (pooled OR 2.42, 95% CI 1.26 to 4.68; P < .008).18 A second meta-analysis that pooled data from seven studies (six randomized controlled studies) confirmed that ultrasound guidance improves success rates of PIV insertion (OR 3.96, 95% CI 1.75 to 8.94).19 Approximately half of these studies had physician operators while the other half had nurse operators.
In one prospective observational study of emergency department patients with two failed attempts of landmark-based PIV insertion, ultrasound guidance with a modified-Seldinger technique showed a relatively high success rate (96%), fewer needle sticks (mean 1.32 sticks, 95% CI 1.12 to 1.52), and shorter time to obtain access (median time 68 seconds).114 Other prospective observational studies have demonstrated that ultrasound guidance for PIV insertion has a high success rate (87%),115 particularly with brachial or basilic veins PIV insertion, among patients with difficult PIV access, defined as having had ≥2 failed attempts.58
Since insertion of PIVs with ultrasound guidance has a high success rate, there is potential to reduce the reliance on CVC insertion for venous access only. In a study of patients that had had two failed attempts at PIV insertion based on landmarks, a PIV was successfully inserted with ultrasound guidance in 84% of patients, obviating the need for CVC placement for venous access.116 A prospective observational study showed ultrasound-guided PIV insertion was an effective alternative to CVC placement in ED patients with difficult venous access with only 1% of patients requiring a CVC.117 Use of ultrasound by nurses for PIV placement has also been shown to reduce the time to obtain venous access, improve patient satisfaction, and reduce the need for physician intervention.118 In a prospective observational study of patients with difficult access, the majority of patients reported a better experience with ultrasound-guided PIV insertion compared to previous landmark-based attempts with an average satisfaction score of 9.2/10 with 76% of patients rating the experience a 10.119 A strong recommendation has been made for use of ultrasound guidance in patients with difficult PIV placement by la Société Française d’Anesthésie et de Réanimation (The French Society of Anesthesia and Resuscitation).95
17. We suggest using real-time ultrasound guidance to reduce the risk of vascular, infectious, and neurological complications during PIV insertion, particularly in patients with difficult venous access.
Rationale: The incidence of complications from PIV insertion is often underestimated. Vascular complications include arterial puncture, hematoma formation, local infiltration or extravasation of fluid, and superficial or deep venous thrombosis. The most common infectious complications with PIV insertion are phlebitis and cellulitis.120 One observational study reported PIV complications occurring in approximately half of all patients with the most common complications being phlebitis, hematoma formation, and fluid/blood leakage.121
A retrospective review of ICU patients who underwent ultrasound-guided PIV insertion by a single physician showed high success rates (99%) with low rates of phlebitis/cellulitis (0.7%).There was an assumed benefit of risk reduction due to the patients no longer requiring a CVC after successful PIV placement.122 Another study found very low rates of infection with both landmark-based and ultrasound-guided PIV placement performed by emergency department nurses, suggesting that there is no increased risk of infection with the use of ultrasound.123 To reduce the risk of infection from PIV insertion, we recommend the use of sterile gel and sterile transducer cover (See Recommendation 2).
Arterial Access Techniques
18. We recommend that providers should use real-time ultrasound guidance for arterial access, which has been shown to increase first-pass success rates, reduce the time to cannulation, and reduce the risk of hematoma development compared with landmark-based techniques.
Rationale: Several randomized controlled studies have assessed the value of ultrasound in arterial catheter insertion. Shiver et al. randomized 60 patients admitted to a tertiary center emergency department to either palpation or ultrasound-guided arterial cannulation. They demonstrated a first-pass success rate of 87% in the ultrasound group compared with 50% in the landmark technique group. In the same study, the use of ultrasound was also associated with reduced time needed to establish arterial access and a 43% reduction in the development of hematoma at the insertion site.124 Levin et al. demonstrated a first-pass success rate of 62% using ultrasound versus 34% by palpation alone in 69 patients requiring intraoperative invasive hemodynamic monitoring.125 Additional randomized controlled studies have demonstrated that ultrasound guidance increases first-attempt success rates compared to traditional palpation.23,126,127
19. We recommend that providers should use real-time ultrasound guidance for femoral arterial access, which has been shown to increase first-pass success rates and reduce the risk of vascular complications.
Rationale: Although it is a less frequently used site, the femoral artery may be accessed for arterial blood sampling or invasive hemodynamic monitoring, and use of ultrasound guidance has been shown to improve the first-pass success rates of femoral artery cannulation. It is important to note that most of these studies comparing ultrasound-guided vs landmark-based femoral artery cannulation were performed in patients undergoing diagnostic or interventional vascular procedures.
A meta-analysis of randomized controlled studies comparing ultrasound-guided vs landmark-based femoral artery catheterization found use of ultrasound guidance was associated with a 49% reduction in overall complications (RR 0.51, 95% CI 0.28 to 0.91; P > .05) and 42% improvement in first-pass success rates.128 In another study, precise site selection with ultrasound was associated with fewer pseudoaneurysms in patients undergoing femoral artery cannulation by ultrasound guidance vs palpation for cardiac catheterization (3% vs 5%, P < .05).129
A multicenter randomized controlled study comparing ultrasound vs fluoroscopic guidance for femoral artery catheterization demonstrated ultrasound guidance improved rates of common femoral artery (CFA) cannulation in patients with high CFA bifurcations (83% vs 70%, P < .01).130 Furthermore, ultrasound guidance improved first-pass success rates (83% vs 46%, P < .0001), reduced number of attempts (1.3 vs 3.0, P < .0001), reduced risk of venipuncture (2.4% vs 15.8%, P < .0001), and reduced median time to obtain access (136 seconds vs148 seconds, P = .003). Vascular complications occurred in fewer patients in the ultrasound vs fluoroscopy groups (1.4% vs 3.4% P = .04). Reduced risk of hematoma formation with routine use of ultrasound guidance was demonstrated in one retrospective observational study (RR 0.62, 95% CI 0.46 to 0.84; P < .01).131
20. We recommend that providers should use real-time ultrasound guidance for radial arterial access, which has been shown to increase first-pass success rates, reduce the time to successful cannulation, and reduce the risk of complications compared with landmark-based techniques.
Rationale: Ultrasound guidance is particularly useful for radial artery cannulation in patients with altered anatomy, obesity, nonpulsatile blood flow, low perfusion, and previously unsuccessful cannulation attempts using a landmark-guided approach.132
A multicenter randomized controlled study that was not included in the abovementioned meta-analyses showed similar benefits of using ultrasound guidance vs landmarks for radial artery catheterization: a reduction in the number of attempts with ultrasound guidance (1.65 ± 1.2 vs 3.05 ± 3.4, P < .0001) and time to obtain access (88 ± 78 vs 108 ± 112 seconds, P = .006), and increased first-pass success rates (65% vs 44%, P < .0001). The use of ultrasound guidance was found to be particularly useful in patients with difficult access by palpation alone.135
Regarding the level of expertise required to use ultrasound guidance, a prospective observational study demonstrated that physicians with little previous ultrasound experience were able to improve their first-attempt success rates and procedure time for radial artery cannulation compared to historical data of landmark-based insertions.136
Postprocedure
21. We recommend that post-procedure pneumothorax should be ruled out by the detection of bilateral lung sliding using a high-frequency linear transducer before and after insertion of internal jugular and subclavian vein CVCs.
Rationale: Detection of lung sliding with two-dimensional ultrasound rules out pneumothorax, and disappearance of lung sliding in an area where it was previously seen is a strong predictor of postprocedure pneumothorax. In a study of critically ill patients, the disappearance of lung sliding was observed in 100% of patients with pneumothorax vs 8.8% of patients without pneumothorax. For detection of pneumothorax, lung sliding showed a sensitivity of 95%, specificity of 91%, and negative predictive value of 100% (P < .001).137 Another study by the same author showed that the combination of horizontal artifacts (absence of comet-tail artifact) and absence of lung sliding had a sensitivity of 100%, specificity of 96.5%, and negative predictive value of 100% for the detection of pneumothorax.138 A meta-analysis of 10 studies on the diagnostic accuracy of CVC confirmation with bedside ultrasound vs chest radiography reported detection of all 12 pneumothoraces with ultrasound, whereas chest radiography missed two pneumothoraces. The pooled sensitivity and specificity of ultrasound for the detection of pneumothorax was 100%, although an imperfect gold standard bias likely affected the results. An important advantage of bedside ultrasound is the ability to rule out pneumothorax immediately after the procedure while at the bedside. The mean time for confirmation of CVC placement with bedside ultrasound was 6 minutes versus 64 minutes and 143 minutes for completion and interpretation of a chest radiograph, respectively.139
22. We recommend that providers should use ultrasound with rapid infusion of agitated saline to visualize a right atrial swirl sign (RASS) for detecting catheter tip misplacement during CVC insertion. The use of RASS to detect the catheter tip may be considered an advanced skill that requires specific training and expertise.
Rationale: Bedside echocardiography is a reliable tool to detect catheter tip misplacement during CVC insertion. In one study, catheter misplacement was detected by bedside echocardiography with a sensitivity of 96% and specificity of 83% (positive predictive value 98%, negative predictive value 55%) and prevented distal positioning of the catheter tip.140 A prospective observational study assessed for RASS, which is turbulent flow in the right atrium after a rapid saline flush of the distal CVC port, to exclude catheter malposition. In this study with 135 CVC placements, visualization of RASS with ultrasound was able to identify all correct CVC placements and three of four catheter misplacements. Median times to complete the ultrasound exam vs CXR were 1 vs 20 minutes, respectively, with a median difference of 24 minutes (95% CI 19.6 to 29.3, P < .0001) between the two techniques.141
A prospective observational study assessed the ability of bedside transthoracic echocardiography to detect the guidewire, microbubbles, or both, in the right atrium compared to transesophageal echocardiography as the gold standard. Bedside transthoracic echocardiography allowed visualization of the right atrium in 94% of patients, and both microbubbles plus guidewire in 91% of patients.142 Hence, bedside transthoracic echocardiography allows adequate visualization of the right atrium. Another prospective observational study combining ultrasonography and contrast enhanced RASS resulted in 96% sensitivity and 93% specificity for the detection of a misplaced catheter, and the concordance with chest radiography was 96%.143
Training
23. To reduce the risk of mechanical and infectious complications, we recommend that novice providers should complete a systematic training program that includes a combination of simulation-based practice, supervised insertion on patients, and evaluation by an expert operator before attempting ultrasound-guided CVC insertion independently on patients.
Rationale: Cumulative experience has been recognized to not be a proxy for mastery of a clinical skill.144 The National Institute for Clinical Excellence (NICE) has recommended that providers performing ultrasound-guided CVC insertion should receive appropriate training to achieve competence before performing the procedure independently.7 Surveys have demonstrated that lack of training is a commonly reported barrier for not using ultrasound.145,146
Structured training programs on CVC insertion have been shown to reduce the occurrence of infectious and mechanical complications.74,143,147-149 The use of ultrasound and checklists, bundling of supplies, and practice with simulation models, as a part of a structured training program, can improve patient safety related to CVC insertion.9,140,150-154
Simulation-based practice has been used in medical education to provide deliberate practice and foster skill development in a controlled learning environment.155-158 Studies have shown transfer of skills demonstrated in a simulated environment to clinical practice, which can improve CVC insertion practices.159,160 Simulation accelerates learning of all trainees, especially novice trainees, and mitigates risks to patients by allowing trainees to achieve a minimal level of competence before attempting the procedure on real patients.152,161,162 Residents that have been trained using simulation preferentially select the IJV site,147 and more reliably use ultrasound to guide their CVC insertions.160,163
Additionally, simulation-based practice allows exposure to procedures and scenarios that may occur infrequently in clinical practice.
Although there is evidence on efficacy of simulation-based CVC training programs, there is no broadly accepted consensus on timing, duration, and content of CVC training programs for trainees or physicians in practice. The minimum recommended technical skills a trainee must master include the ability to (1) manipulate the ultrasound machine to produce a high-quality image to identify the target vessel, (2) advance the needle under direct visualization to the desired target site and depth, (3) deploy the catheter into the target vessel and confirm catheter placement in the target vessel using ultrasound, and (4) ensure the catheter has not been inadvertently placed in an unintended vessel or structure.153
A variety of simulation models are currently used to practice CVC insertion at the most common sites: the internal jugular, subclavian, basilic, and brachial veins.164,165 Effective simulation models should contain vessels that mimic normal anatomy with muscles, soft tissues, and bones. Animal tissue models, such as turkey or chicken breasts, may be effective for simulated practice of ultrasound-guided CVC insertion.166,167 Ultrasound-guided CVC training using human cadavers has also been shown to be effective.168
24. We recommend that cognitive training in ultrasound-guided CVC insertion should include basic anatomy, ultrasound physics, ultrasound machine knobology, fundamentals of image acquisition and interpretation, detection and management of procedural complications, infection prevention strategies, and pathways to attain competency.
Rationale: After receiving training in ultrasound-guided CVC insertion, physicians report significantly higher comfort with the use of ultrasound compared to those who have not received such training.145 Learners find training sessions worthwhile to increase skill levels,167 and skills learned from simulation-based mastery learning programs have been retained up to one year.158
Several commonalities have been noted across training curricula. Anatomy and physiology didactics should include vessel anatomy (location, size, and course);9 vessel differentiation by ultrasound;9,69 blood flow dynamics;69 Virchow’s triad;69 skin integrity and colonization;150 peripheral nerve identification and distribution;9 respiratory anatomy;9,69 upper and lower extremity, axillary, neck, and chest anatomy.9,69 Vascular anatomy is an essential curricular component that may help avoid preventable CVC insertion complications, such as inadvertent nerve, artery, or lung puncture.150,169 Training curricula should also include ultrasound physics (piezoelectric effect, frequency, resolution, attenuation, echogenicity, Doppler ultrasound, arterial and venous flow characteristics), image acquisition and optimization (imaging mode, focus, dynamic range, probe types), and artifacts (reverberation, mirror, shadowing, enhancement).
CVC-related infections are an important cause of morbidity and mortality in the acute and long-term care environment.69 Infection and thrombosis can both be impacted by the insertion site selection, skin integrity, and catheter–vein ratio.2,3,84 Inexperience generally leads to more insertion attempts that can increase trauma during CVC insertion and potentially increase the risk of infections.170 To reduce the risk of infectious complications, training should include important factors to consider in site selection and maintenance of a sterile environment during CVC insertion, including use of maximal sterile barrier precautions, hand hygiene, and appropriate use of skin antiseptic solutions.
Professional society guidelines have been published with recommendations of appropriate techniques for ultrasound-guided vascular access that include training recommendations.9,154 Training should deconstruct the insertion procedure into readily understood individual steps, and can be aided by demonstration of CVC insertion techniques using video clips. An alternative to face-to-face training is internet-based training that has been shown to be as effective as traditional teaching methods in some medical centers.171 Additional methods to deliver cognitive instruction include textbooks, continuing medical education courses, and digital videos.164,172
25. We recommend that trainees should demonstrate minimal competence before placing ultrasound-guided CVCs independently. A minimum number of CVC insertions may inform this determination, but a proctored assessment of competence is most important.
Rationale: CVC catheter placement carries the risk of serious complications including arterial injury or dissection, pneumothorax, or damage to other local structures; arrhythmias; catheter malposition; infection; and thrombosis. Although there is a lack of consensus and high-quality evidence for the certification of skills to perform ultrasound-guided CVC insertion, recommendations have been published advocating for formal and comprehensive training programs in ultrasound-guided CVC insertion with an emphasis on expert supervision prior to independent practice.9,153,154 Two groups of expert operators have recommended that training should include at least 8-10 supervised ultrasound-guided CVC insertions.154,173,174 A consensus task force from the World Congress of Vascular Access has recommended a minimum of six to eight hours of didactic education, four hours of hands-on training on simulation models, and six hours of hands-on ultrasound training on human volunteers to assess normal anatomy.175 This training should be followed by supervised ultrasound-guided CVC insertions until the learner has demonstrated minimal competence with a low rate of complications.35 There is general consensus that arbitrary numbers should not be the sole determinant of competence, and that the most important determinant of competence should be an evaluation by an expert operator.176
26. We recommend that didactic and hands-on training for trainees should coincide with anticipated times of increased performance of vascular access procedures. Refresher training sessions should be offered periodically.
Rationale: Simulation-based CVC training courses have shown a rapid improvement in skills, but lack of practice leads to deterioration of technical skills.161,162,177,178 Thus, a single immersive training session is insufficient to achieve and maintain mastery of skills, and an important factor to acquire technical expertise is sustained, deliberate practice with feedback.179 Furthermore, an insidious decay in skills may go unrecognized as a learner’s comfort and self-confidence does not always correlate with actual performance, leading to increased risk of errors and potential for procedural complications.147,158,180-183 Given the decay in technical skills over time, simulation-based training sessions are most effective when they occur in close temporal proximity to times when those skills are most likely to be used; for example, a simulation-based training session for trainees may be most effective just before the start of a critical care rotation.152 Regularly scheduled training sessions with monitoring and feedback by expert operators can reinforce procedural skills and prevent decay. Some experts have recommended that a minimum of 10 ultrasound-guided CVC insertions should be performed annually to maintain proficiency.153
27. We recommend that competency assessments should include formal evaluation of knowledge and technical skills using standardized assessment tools.
Rationale: Hospitalists and other healthcare providers that place vascular access catheters should undergo competency assessments proctored by an expert operator to verify that they have the required knowledge and skills.184,185 Knowledge competence can be partially evaluated using a written assessment, such as a multiple-choice test, assessing the provider’s cognitive understanding of the procedure.175 For ultrasound-guided CVC insertion, a written examination should be administered in conjunction with an ultrasound image assessment to test the learner’s recognition of normal vs abnormal vascular anatomy. Minimum passing standards should be established a priori according to local or institutional standards.
The final skills assessment should be objective, and the learner should be required to pass all critical steps of the procedure. Failure of the final skills assessment should lead to continued practice with supervision until the learner can consistently demonstrate correct performance of all critical steps. Checklists are commonly used to rate the technical performance of learners because they provide objective criteria for evaluation, can identify specific skill deficiencies, and can determine a learner’s readiness to perform procedures independently.186,187 The administration of skills assessments and feedback methods should be standardized across faculty. Although passing scores on both knowledge and skills assessments do not guarantee safe performance of a procedure independently, they provide a metric to ensure that a minimum level of competence has been achieved before allowing learners to perform procedures on patients without supervision.188
Competency assessments are a recommended component of intramural and extramural certification of skills in ultrasound-guided procedures. Intramural certification pathways differ by institution and often require additional resources including ultrasound machine(s), simulation equipment, and staff time, particularly when simulation-based assessments are incorporated into certification pathways. We recognize that some of these recommendations may not be feasible in resource-limited settings, such as rural hospitals. However, initial and ongoing competency assessments can be performed during routine performance of procedures on patients. For an in-depth review of credentialing pathways for ultrasound-guided bedside procedures, we recommend reviewing the SHM Position Statement on Credentialing of Hospitalists in Ultrasound-Guided Bedside Procedures.24
28. We recommend that competency assessments should evaluate for proficiency in the following knowledge and skills of CVC insertion:
a. Knowledge of the target vein anatomy, proper vessel identification, and recognition of anatomical variants
b. Demonstration of CVC insertion with no technical errors based on a procedural checklist
c. Recognition and management of acute complications, including emergency management of life-threatening complications
d. Real-time needle tip tracking with ultrasound and cannulation on the first attempt in at least five consecutive simulations.
Rationale: Recommendations have been published with the minimal knowledge and skills learners must demonstrate to perform ultrasound-guided vascular access procedures. These include operation of an ultrasound machine to produce high-quality images of the target vessel, tracking of the needle tip with real-time ultrasound guidance, and recognition and understanding of the management of procedural complications.154,175
First, learners must be able to perform a preprocedural assessment of the target vein, including size and patency of the vein; recognition of adjacent critical structures; and recognition of normal anatomical variants.175,189 Second, learners must be able to demonstrate proficiency in tracking the needle tip penetrating the target vessel, inserting the catheter into the target vessel, and confirming catheter placement in the target vessel with ultrasound.154,175 Third, learners must be able to demonstrate recognition of acute complications, including arterial puncture, hematoma formation, and development of pneumothorax.154,175 Trainees should be familiar with recommended evaluation and management algorithms, including indications for emergent consultation.190
29. We recommend a periodic proficiency assessments of all operators should be conducted to ensure maintenance of competency.
Rationale: Competency extends to periodic assessment and not merely an initial evaluation at the time of training.191 Periodic competency assessments should include assessment of proficiency of all providers that perform a procedure, including instructors and supervisors. Supervising providers should maintain their competency in CVC insertion through routine use of their skills in clinical practice.175 An observational study of emergency medicine residents revealed that lack of faculty comfort with ultrasound hindered the residents’ use of ultrasound.192 Thus, there is a need to examine best practices for procedural supervision of trainees because providers are often supervising procedures that they are not comfortable performing on their own.193
KNOWLEDGE GAPS
The process of producing this position statement revealed areas of uncertainty and important gaps in the literature regarding the use of ultrasound guidance for central and peripheral venous access and arterial access.
This position statement recommends a preprocedural ultrasound evaluation of blood vessels based on evidence that providers may detect anatomic anomalies, thrombosis, or vessel stenosis. Ultrasound can also reveal unsuspected high-risk structures in near proximity to the procedure site. Although previous studies have shown that providers can accurately assess vessels with ultrasound for these features, further study is needed to evaluate the effect of a standardized preprocedural ultrasound exam on clinical and procedural decision-making, as well as procedural outcomes.
Second, two ultrasound applications that are being increasingly used but have not been widely implemented are the use of ultrasound to evaluate lung sliding postprocedure to exclude pneumothorax and the verification of central line placement using a rapid infusion of agitated saline to visualize the RASS.139-141 Both of these applications have the potential to expedite postprocedure clearance of central lines for usage and decrease patient radiation exposure by obviating the need for postprocedure CXRs. Despite the supporting evidence, both of these applications are not yet widely used, as few providers have been trained in these techniques which may be considered advanced skills.
Third, despite advances in our knowledge of effective training for vascular access procedures, there is limited agreement on how to define procedural competence. Notable advancements in training include improved understanding of systematic training programs, development of techniques for proctoring procedures, definition of elements for hands-on assessments, and definition of minimum experience needed to perform vascular access procedures independently. However, application of these concepts to move learners toward independent practice remains variably interpreted at different institutions, likely due to limited resources, engrained cultures about procedures, and a lack of national standards. The development of hospitalist-based procedure services at major academic medical centers with high training standards, close monitoring for quality assurance, and the use of databases to track clinical outcomes may advance our understanding and delivery of optimal procedural training.
Finally, ultrasound technology is rapidly evolving which will affect training, techniques, and clinical outcomes in coming years. Development of advanced imaging software with artificial intelligence can improve needle visualization and tracking. These technologies have the potential to facilitate provider training in real-time ultrasound-guided procedures and improve the overall safety of procedures. Emergence of affordable, handheld ultrasound devices is improving access to ultrasound technology, but their role in vascular access procedures is yet to be defined. Furthermore, availability of wireless handheld ultrasound technology and multifrequency transducers will create new possibilities for use of ultrasound in vascular access procedures.
CONCLUSION
We have presented several evidence-based recommendations on the use of ultrasound guidance for placement of central and peripheral vascular access catheters that are intended for hospitalists and other healthcare providers who routinely perform vascular access procedures. By allowing direct visualization of the needle tip and target vessel, the use of ultrasound guidance has been shown in randomized studies to reduce needle insertion attempts, reduce needle redirections, and increase overall procedure success rates. The accuracy of ultrasound to identify the target vessel, assess for thrombosis, and detect anatomical anomalies is superior to that of physical examination. Hospitalists can attain competence in performing ultrasound-guided vascular access procedures through systematic training programs that combine didactic and hands-on training, which optimally include patient-based competency assessments.
Acknowledgments
The authors thank all the members of the Society of Hospital Medicine Point-of-care Ultrasound Task Force and the Education Committee members for their time and dedication to develop these guidelines.
Collaborators of Society of Hospital Medicine Point-of-care Ultrasound Task Force: Robert Arntfield, Jeffrey Bates, Anjali Bhagra, Michael Blaivas, Daniel Brotman, Richard Hoppmann, Susan Hunt, Trevor P. Jensen, Venkat Kalidindi, Ketino Kobaidze, Joshua Lenchus, Paul Mayo, Satyen Nichani, Vicki Noble, Nitin Puri, Aliaksei Pustavoitau, Kreegan Reierson, Gerard Salame, Kirk Spencer, Vivek Tayal, David Tierney
SHM Point-of-care Ultrasound Task Force: CHAIRS: Nilam J. Soni, Ricardo Franco-Sadud, Jeff Bates. WORKING GROUPS: Thoracentesis Working Group: Ria Dancel (chair), Daniel Schnobrich, Nitin Puri. Vascular Access Working Group: Ricardo Franco (chair), Benji Mathews, Saaid Abdel-Ghani, Sophia Rodgers, Martin Perez, Daniel Schnobrich. Paracentesis Working Group: Joel Cho (chair), Benji Mathews, Kreegan Reierson, Anjali Bhagra, Trevor P. Jensen Lumbar Puncture Working Group: Nilam J. Soni (chair), Ricardo Franco, Gerard Salame, Josh Lenchus, Venkat Kalidindi, Ketino Kobaidze. Credentialing Working Group: Brian P Lucas (chair), David Tierney, Trevor P. Jensen PEER REVIEWERS: Robert Arntfield, Michael Blaivas, Richard Hoppmann, Paul Mayo, Vicki Noble, Aliaksei Pustavoitau, Kirk Spencer, Vivek Tayal. METHODOLOGIST: Mahmoud El-Barbary. LIBRARIAN: Loretta Grikis. SOCIETY OF HOSPITAL MEDICINE EDUCATION COMMITTEE: Daniel Brotman (past chair), Satyen Nichani (current chair), Susan Hunt. SOCIETY OF HOSPITAL MEDICINE STAFF: Nick Marzano.
Disclaimer
The contents of this publication do not represent the views of the U.S. Department of Veterans Affairs or the United States Government.
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115. Brannam L, Blaivas M, Lyon M, Flake M. Emergency nurses’ utilization of ultrasound guidance for placement of peripheral intravenous lines in difficult-access patients. Acad Emerg Med. 2004;11(12):1361-1363. https://doi.org/10.1197/j.aem.2004.08.027.
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Approximately five million central venous catheters (CVCs) are inserted in the United States annually, with over 15 million catheter days documented in intensive care units alone.1 Traditional CVC insertion techniques using landmarks are associated with a high risk of mechanical complications, particularly pneumothorax and arterial puncture, which occur in 5%-19% patients.2,3
Since the 1990s, several randomized controlled studies and meta-analyses have demonstrated that the use of real-time ultrasound guidance for CVC insertion increases procedure success rates and decreases mechanical complications.4,5 Use of real-time ultrasound guidance was recommended by the Agency for Healthcare Research and Quality, the Institute of Medicine, the National Institute for Health and Care Excellence, the Centers for Disease Control and Prevention, and several medical specialty societies in the early 2000s.6-14 Despite these recommendations, ultrasound guidance has not been universally adopted. Currently, an estimated 20%-55% of CVC insertions in the internal jugular vein are performed without ultrasound guidance.15-17
Following the emergence of literature supporting the use of ultrasound guidance for CVC insertion, observational and randomized controlled studies demonstrated improved procedural success rates with the use of ultrasound guidance for the insertion of peripheral intravenous lines (PIVs), arterial catheters, and peripherally inserted central catheters (PICCs).18-23
The purpose of this position statement is to present evidence-based recommendations on the use of ultrasound guidance for the insertion of central and peripheral vascular access catheters in adult patients. This document presents consensus-based recommendations with supporting evidence for clinical outcomes, techniques, and training for the use of ultrasound guidance for vascular access. We have subdivided the recommendations on techniques for central venous access, peripheral venous access, and arterial access individually, as some providers may not perform all types of vascular access procedures.
These recommendations are intended for hospitalists and other healthcare providers that routinely place central and peripheral vascular access catheters in acutely ill patients. However, this position statement does not mandate that all hospitalists should place central or peripheral vascular access catheters given the diverse array of hospitalist practice settings. For training and competency assessments, we recognize that some of these recommendations may not be feasible in resource-limited settings, such as rural hospitals, where equipment and staffing for assessments are not available. Recommendations and frameworks for initial and ongoing credentialing of hospitalists in ultrasound-guided bedside procedures have been previously published in an Society of Hospital Medicine (SHM) position statement titled, “Credentialing of Hospitalists in Ultrasound-Guided Bedside Procedures.”24
METHODS
Detailed methods are described in Appendix 1. The SHM Point-of-care Ultrasound (POCUS) Task Force was assembled to carry out this guideline development project under the direction of the SHM Board of Directors, Director of Education, and Education Committee. All expert panel members were physicians or advanced practice providers with expertise in POCUS. Expert panel members were divided into working group members, external peer reviewers, and a methodologist. All Task Force members were required to disclose any potential conflicts of interest (Appendix 2). The literature search was conducted in two independent phases. The first phase included literature searches conducted by the vascular access working group members themselves. Key clinical questions and draft recommendations were then prepared. A systematic literature search was conducted by a medical librarian based on the findings of the initial literature search and draft recommendations. The Medline, Embase, CINAHL, and Cochrane medical databases were searched from 1975 to December 2015 initially. Google Scholar was also searched without limiters. An updated search was conducted in November 2017. The literature search strings are included in Appendix 3. All article abstracts were initially screened for relevance by at least two members of the vascular access working group. Full-text versions of screened articles were reviewed, and articles on the use of ultrasound to guide vascular access were selected. The following article types were excluded: non-English language, nonhuman, age <18 years, meeting abstracts, meeting posters, narrative reviews, case reports, letters, and editorials. All relevant systematic reviews, meta-analyses, randomized controlled studies, and observational studies of ultrasound-guided vascular access were screened and selected (Appendix 3, Figure 1). All full-text articles were shared electronically among the working group members, and final article selection was based on working group consensus. Selected articles were incorporated into the draft recommendations.
These recommendations were developed using the Research and Development (RAND) Appropriateness Method that required panel judgment and consensus.14 The 28 voting members of the SHM POCUS Task Force reviewed and voted on the draft recommendations considering five transforming factors: (1) Problem priority and importance, (2) Level of quality of evidence, (3) Benefit/harm balance, (4) Benefit/burden balance, and (5) Certainty/concerns about PEAF (Preferences/Equity/Acceptability/Feasibility). Using an internet-based electronic data collection tool (REDCap™), panel members participated in two rounds of electronic voting, one in August 2018 and the other in October 2018 (Appendix 4). Voting on appropriateness was conducted using a nine-point Likert scale. The three zones of the nine-point Likert scale were inappropriate (1-3 points), uncertain (4-6 points), and appropriate (7-9 points). The degree of consensus was assessed using the RAND algorithm (Appendix 1, Figure 1 and Table 1). Establishing a recommendation required at least 70% agreement that a recommendation was “appropriate.” Disagreement was defined as >30% of panelists voting outside of the zone of the median. A strong recommendation required at least 80% of the votes within one integer of the median per the RAND rules.
Recommendations were classified as strong or weak/conditional based on preset rules defining the panel’s level of consensus, which determined the wording for each recommendation (Table 2). The final version of the consensus-based recommendations underwent internal and external review by members of the SHM POCUS Task Force, the SHM Education Committee, and the SHM Executive Committee. The SHM Executive Committee reviewed and approved this position statement prior to its publication in the Journal of Hospital Medicine.
RESULTS
Literature Search
A total of 5,563 references were pooled from an initial search performed by a certified medical librarian in December 2015 (4,668 citations) which was updated in November 2017 (791 citations), and from the personal bibliographies and searches (104 citations) performed by working group members. A total of 514 full-text articles were reviewed. The final selection included 192 articles that were abstracted into a data table and incorporated into the draft recommendations. See Appendix 3 for details of the literature search strategy.
Recommendations
Four domains (technique, clinical outcomes, training, and knowledge gaps) with 31 draft recommendations were generated based on a review of the literature. Selected references were abstracted and assigned to each draft recommendation. Rationales for each recommendation cite supporting evidence. After two rounds of panel voting, 31 recommendations achieved agreement based on the RAND rules. During the peer review process, two of the recommendations were merged with other recommendations. Thus, a total of 29 recommendations received final approval. The degree of consensus based on the median score and the dispersion of voting around the median are shown in Appendix 5. Twenty-seven statements were approved as strong recommendations, and two were approved as weak/conditional recommendations. The strength of each recommendation and degree of consensus are summarized in Table 3.
Terminology
Central Venous Catheterization
Central venous catheterization refers to insertion of tunneled or nontunneled large bore vascular catheters that are most commonly inserted into the internal jugular, subclavian, or femoral veins with the catheter tip located in a central vein. These vascular access catheters are synonymously referred to as central lines or central venous catheters (CVCs). Nontunneled catheters are designed for short-term use and should be removed promptly when no longer clinically indicated or after a maximum of 14 days.25
Peripherally Inserted Central Catheter (PICC)
Peripherally inserted central catheters, or PICC lines, are inserted most commonly in the basilic or brachial veins in adult patients, and the catheter tip terminates in the distal superior vena cava or cavo-atrial junction. These catheters are designed to remain in place for a duration of several weeks, as long as it is clinically indicated.
Midline Catheterization
Midline catheters are a type of peripheral venous catheter that are an intermediary between a peripheral intravenous catheter and PICC line. Midline catheters are most commonly inserted in the brachial or basilic veins, but unlike PICC lines, the tips of these catheters terminate in the axillary or subclavian vein. Midline catheters are typically 8 cm to 20 cm in length and inserted for a duration <30 days.
Peripheral Intravenous Catheterization
Peripheral intravenous lines (PIV) refer to small bore venous catheters that are most commonly 14G to 24G and inserted into patients for short-term peripheral venous access. Common sites of ultrasound-guided PIV insertion include the superficial and deep veins of the hand, forearm, and arm.
Arterial Catheterization
Arterial catheters are commonly used for reliable blood pressure monitoring, frequent arterial blood
RECOMMENDATIONS
Preprocedure
1. We recommend that providers should be familiar with the operation of their specific ultrasound machine prior to initiation of a vascular access procedure.
Rationale: There is strong consensus that providers must be familiar with the knobs and functions of the specific make and model of ultrasound machine that will be utilized for a vascular access procedure. Minimizing adjustments to the ultrasound machine during the procedure may reduce the risk of contaminating the sterile field.
2. We recommend that providers should use a high-frequency linear transducer with a sterile sheath and sterile gel to perform vascular access procedures.
Rationale: High-frequency linear-array transducers are recommended for the vast majority of vascular access procedures due to their superior resolution compared to other transducer types. Both central and peripheral vascular access procedures, including PIV, PICC, and arterial line placement, should be performed using sterile technique. A sterile transducer cover and sterile gel must be utilized, and providers must be trained in sterile preparation of the ultrasound transducer.13,26,27
The depth of femoral vessels correlates with body mass index (BMI). When accessing these vessels in a morbidly obese patient with a thigh circumference >60 cm and vessel depth >8 cm, a curvilinear transducer may be preferred for its deeper penetration.28 For patients who are poor candidates for bedside insertion of vascular access catheters, such as uncooperative patients, patients with atypical vascular anatomy or poorly visualized target vessels, we recommend consultation with a vascular access specialist prior to attempting the procedure.
3. We recommend that providers should use two-dimensional ultrasound to evaluate for anatomical variations and absence of vascular thrombosis during preprocedural site selection.
Rationale: A thorough ultrasound examination of the target vessel is warranted prior to catheter placement. Anatomical variations that may affect procedural decision-making are easily detected with ultrasound. A focused vascular ultrasound examination is particularly important in patients who have had temporary or tunneled venous catheters, which can cause stenosis or thrombosis of the target vein.
For internal jugular vein (IJV) CVCs, ultrasound is useful for visualizing the relationship between the IJV and common carotid artery (CCA), particularly in terms of vessel overlap. Furthermore, ultrasound allows for immediate revisualization upon changes in head position.29-32 Troianos et al. found >75% overlap of the IJV and CCA in 54% of all patients and in 64% of older patients (age >60 years) whose heads were rotated to the contralateral side.30 In one study of IJV CVC insertion, inadvertent carotid artery punctures were reduced (3% vs 10%) with the use of ultrasound guidance vs landmarks alone.33 In a cohort of 64 high-risk neurosurgical patients, cannulation success was 100% with the use of ultrasound guidance, and there were no injuries to the carotid artery, even though the procedure was performed with a 30-degree head elevation and anomalous IJV anatomy in 39% of patients.34 In a prospective, randomized controlled study of 1,332 patients, ultrasound-guided cannulation in a neutral position was demonstrated to be as safe as the 45-degree rotated position.35
Ultrasound allows for the recognition of anatomical variations which may influence the selection of the vascular access site or technique. Benter et al. found that 36% of patients showed anatomical variations in the IJV and surrounding tissue.36 Similarly Caridi showed the anatomy of the right IJV to be atypical in 29% of patients,37 and Brusasco found that 37% of bariatric patients had anatomical variations of the IJV.38 In a study of 58 patients, there was significant variability in the IJV position and IJV diameter, ranging from 0.5 cm to >2 cm.39 In a study of hemodialysis patients, 75% of patients had sonographic venous abnormalities that led to a change in venous access approach.40
To detect acute or chronic upper extremity deep venous thrombosis or stenosis, two-dimensional visualization with compression should be part of the ultrasound examination prior to central venous catheterization. In a study of patients that had undergone CVC insertion 9-19 weeks earlier, 50% of patients had an IJV thrombosis or stenosis leading to selection of an alternative site. In this study, use of ultrasound for a preprocedural site evaluation reduced unnecessary attempts at catheterizing an occluded vein.41 At least two other studies demonstrated an appreciable likelihood of thrombosis. In a study of bariatric patients, 8% of patients had asymptomatic thrombosis38 and in another study, 9% of patients being evaluated for hemodialysis catheter placement had asymptomatic IJV thrombosis.37
4. We recommend that providers should evaluate the target blood vessel size and depth during a preprocedural ultrasound evaluation.
Rationale: The size, depth, and anatomic location of central veins can vary considerably. These features are easily discernable using ultrasound. Contrary to traditional teaching, the IJV is located 1 cm anterolateral to the CCA in only about two-thirds of patients.37,39,42,43 Furthermore, the diameter of the IJV can vary significantly, ranging from 0.5 cm to >2 cm.39 The laterality of blood vessels may vary considerably as well. A preprocedural ultrasound evaluation of contralateral subclavian and axillary veins showed a significant absolute difference in cross-sectional area of 26.7 mm2 (P < .001).42
Blood vessels can also shift considerably when a patient is in the Trendelenburg position. In one study, the IJV diameter changed from 11.2 (± 1.5) mm to 15.4 (± 1.5) mm in the supine versus the Trendelenburg position at 15 degrees.33 An observational study demonstrated a frog-legged position with reverse Trendelenburg increased the femoral vein size and reduced the common surface area with the common femoral artery compared to a neutral position. Thus, a frog-legged position with reverse Trendelenburg position may be preferred, since overall catheterization success rates are higher in this position.44
Techniques
General Techniques
5. We recommend that providers should avoid using static ultrasound alone to mark the needle insertion site for vascular access procedures.
Rationale: The use of static ultrasound guidance to mark a needle insertion site is not recommended because normal anatomical relationships of vessels vary, and site marking can be inaccurate with minimal changes in patient position, especially of the neck.43,45,46 Benefits of using ultrasound guidance for vascular access are attained when ultrasound is used to track the needle tip in real-time as it is advanced toward the target vessel.
Although continuous-wave Doppler ultrasound without two-dimensional visualization was used in the past, it is no longer recommended for IJV CVC insertion.47 In a study that randomized patients to IJV CVC insertion with continuous-wave Doppler alone vs two-dimensional ultrasound guidance, the use of two-dimensional ultrasound guidance showed significant improvement in first-pass success rates (97% vs 91%, P = .045), particularly in patients with BMI >30 (97% vs 77%, P = .011).48
A randomized study comparing real-time ultrasound-guided, landmark-based, and ultrasound-marked techniques found higher success rates in the real-time ultrasound-guided group than the other two groups (100% vs 74% vs 73%, respectively; P = .01). The total number of mechanical complications was higher in the landmark-based and ultrasound-marked groups than in the real-time ultrasound-guided group (24% and 36% versus 0%, respectively; P = .01).49 Another randomized controlled study found higher success rates with real-time ultrasound guidance (98%) versus an ultrasound-marked (82%) or landmark-based (64%) approach for central line placement.50
6. We recommend that providers should use real-time (dynamic), two-dimensional ultrasound guidance with a high-frequency linear transducer for CVC insertion, regardless of the provider’s level of experience.
7. We suggest using either a transverse (short-axis) or longitudinal (long-axis) approach when performing real-time ultrasound-guided vascular access procedures.
Rationale: In clinical practice, the phrases transverse, short-axis, or out-of-plane approach are synonymous, as are longitudinal, long-axis, and in-plane approach. The short-axis approach involves tracking the needle tip as it approximates the target vessel with the ultrasound beam oriented in a transverse plane perpendicular to the target vessel. The target vessel is seen as a circular structure on the ultrasound screen as the needle tip approaches the target vessel from above. This approach is also called the out-of-plane technique since the needle passes through the ultrasound plane. The advantages of the short-axis approach include better visualization of adjacent vessels or nerves and the relative ease of skill acquisition for novice operators.9 When using the short-axis approach, extra care must be taken to track the needle tip from the point of insertion on the skin to the target vessel. A disadvantage of the short-axis approach is unintended posterior wall puncture of the target vessel.55
In contrast to a short-axis approach, a long-axis approach is performed with the ultrasound beam aligned parallel to the vessel. The vessel appears as a long tubular structure and the entire needle is visualized as it traverses across the ultrasound screen to approach the target vessel. The long-axis approach is also called an in-plane technique because the needle is maintained within the plane of the ultrasound beam. The advantage of a long-axis approach is the ability to visualize the entire needle as it is inserted into the vessel.14 A randomized crossover study with simulation models compared a long-axis versus short-axis approach for both IJV and subclavian vein catheterization. This study showed decreased number of needle redirections (relative risk (RR) 0.5, 95% confidence interval (CI) 0.3 to 0.7), and posterior wall penetrations (OR 0.3, 95% CI 0.1 to 0.9) using a long-axis versus short-axis approach for subclavian vein catheterization.56
A randomized controlled study comparing a long-axis or short-axis approach with ultrasound versus a landmark-based approach for IJV CVC insertion showed higher success rates (100% vs 90%; P < .001), lower insertion time (53 vs 116 seconds; P < .001), and fewer attempts to obtain access (2.5 vs 1.2 attempts, P < .001) with either the long- or short-axis ultrasound approach. The average time to obtain access and number of attempts were comparable between the short-axis and long-axis approaches with ultrasound. The incidence of carotid puncture and hematoma was significantly higher with the landmark-based approach versus either the long- or short-axis ultrasound approach (carotid puncture 17% vs 3%, P = .024; hematoma 23% vs 3%, P = .003).57
High success rates have been reported using a short-axis approach for insertion of PIV lines.58 A prospective, randomized trial compared the short-axis and long-axis approach in patients who had had ≥2 failed PIV insertion attempts. Success rate was 95% (95% CI, 0.85 to 1.00) in the short-axis group compared with 85% (95% CI, 0.69 to 1.00) in the long-axis group. All three subjects with failed PIV placement in the long-axis group had successful rescue placement using a short-axis approach. Furthermore, the short-axis approach was faster than the long-axis approach.59
For radial artery cannulation, limited data exist comparing the short- and long-axis approaches. A randomized controlled study compared a long-axis vs short-axis ultrasound approach for radial artery cannulation. Although the overall procedure success rate was 100% in both groups, the long-axis approach had higher first-pass success rates (1.27 ± 0.4 vs 1.5 ± 0.5, P < .05), shorter cannulation times (24 ± 17 vs 47 ± 34 seconds, P < .05), fewer hematomas (4% vs 43%, P < .05) and fewer posterior wall penetrations (20% vs 56%, P < .05).60
Another technique that has been described for IJV CVC insertion is an oblique-axis approach, a hybrid between the long- and short-axis approaches. In this approach, the transducer is aligned obliquely over the IJV and the needle is inserted using a long-axis or in-plane approach. A prospective randomized trial compared the short-axis, long-axis, and oblique-axis approaches during IJV cannulation. First-pass success rates were 70%, 52%, and 74% with the short-axis, long-axis, and oblique-axis approaches, respectively, and a statistically significant difference was found between the long- and oblique-axis approaches (P = .002). A higher rate of posterior wall puncture was observed with a short-axis approach (15%) compared with the oblique-axis (7%) and long-axis (4%) approaches (P = .047).61
8. We recommend that providers should visualize the needle tip and guidewire in the target vein prior to vessel dilatation.
Rationale: When real-time ultrasound guidance is used, visualization of the needle tip within the vein is the first step to confirm cannulation of the vein and not the artery. After the guidewire is advanced, the provider can use transverse and longitudinal views to reconfirm cannulation of the vein. In a longitudinal view, the guidewire is readily seen positioned within the vein, entering the anterior wall and lying along the posterior wall of the vein. Unintentional perforation of the posterior wall of the vein with entry into the underlying artery can be detected by ultrasound, allowing prompt removal of the needle and guidewire before proceeding with dilation of the vessel. In a prospective observational study that reviewed ultrasound-guided IJV CVC insertions, physicians were able to more readily visualize the guidewire than the needle in the vein.62 A prospective observational study determined that novice operators can visualize intravascular guidewires in simulation models with an overall accuracy of 97%.63
In a retrospective review of CVC insertions where the guidewire position was routinely confirmed in the target vessel prior to dilation, there were no cases of arterial dilation, suggesting confirmation of guidewire position can potentially eliminate the morbidity and mortality associated with arterial dilation during CVC insertion.64
9. To increase the success rate of ultrasound-guided vascular access procedures, we recommend that providers should utilize echogenic needles, plastic needle guides, and/or ultrasound beam steering when available.
Rationale: Echogenic needles have ridged tips that appear brighter on the screen, allowing for better visualization of the needle tip. Plastic needle guides help stabilize the needle alongside the transducer when using either a transverse or longitudinal approach. Although evidence is limited, some studies have reported higher procedural success rates when using echogenic needles, plastic needle guides, and ultrasound beam steering software. In a prospective observational study, Augustides et al. showed significantly higher IJV cannulation rates with versus without use of a needle guide after first (81% vs 69%, P = .0054) and second (93% vs 80%. P = .0001) needle passes.65 A randomized study by Maecken et al. compared subclavian vein CVC insertion with or without use of a needle guide, and found higher procedure success rates within the first and second attempts, reduced time to obtain access (16 seconds vs 30 seconds; P = .0001) and increased needle visibility (86% vs 32%; P < .0001) with the use of a needle guide.66 Another study comparing a short-axis versus long-axis approach with a needle guide showed improved needle visualization using a long-axis approach with a needle guide.67 A randomized study comparing use of a novel, sled-mounted needle guide to a free-hand approach for venous cannulation in simulation models showed the novel, sled-mounted needle guide improved overall success rates and efficiency of cannulation.68
Central Venous Access Techniques
10. We recommend that providers should use a standardized procedure checklist that includes use of real-time ultrasound guidance to reduce the risk of central line-associated bloodstream infection (CLABSI) from CVC insertion.
Rationale: A standardized checklist or protocol should be developed to ensure compliance with all recommendations for insertion of CVCs. Evidence-based protocols address periprocedural issues, such as indications for CVC, and procedural techniques, such as use of maximal sterile barrier precautions to reduce the risk of infection. Protocols and checklists that follow established guidelines for CVC insertion have been shown to decrease CLABSI rates.69,70 Similarly, development of checklists and protocols for maintenance of central venous catheters have been effective in reducing CLABSIs.71 Although no externally-validated checklist has been universally accepted or endorsed by national safety organizations, a few internally-validated checklists are available through peer-reviewed publications.72,73 An observational educational cohort of internal medicine residents who received training using simulation of the entire CVC insertion process was able to demonstrate fewer CLABSIs after the simulator-trained residents rotated in the intensive care unit (ICU) (0.50 vs 3.2 infections per 1,000 catheter days, P = .001).74
11. We recommend that providers should use real-time ultrasound guidance, combined with aseptic technique and maximal sterile barrier precautions, to reduce the incidence of infectious complications from CVC insertion.
Rationale: The use of real-time ultrasound guidance for CVC placement has demonstrated a statistically significant reduction in CLABSIs compared to landmark-based techniques.75 The Centers for Disease Control and Prevention (CDC) guidelines for the prevention of intravascular catheter-related infections recommend the use of ultrasound guidance to reduce the number of cannulation attempts and risk of mechanical complications.69 A prospective, three-arm study comparing ultrasound-guided long-axis, short-axis, and landmark-based approaches showed a CLABSI rate of 20% in the landmark-based group versus 10% in each of the ultrasound groups.57 Another randomized study comparing use of ultrasound guidance to a landmark-based technique for IJV CVC insertion demonstrated significantly lower CLABSI rates with the use of ultrasound (2% vs 10%; P < .05).72
Studies have shown that a systems-based intervention featuring a standardized catheter kit or catheter bundle significantly reduced CLABSI rates.76-78 A complete review of all preventive measures to reduce the risk of CLABSI is beyond the scope of this review, but a few key points will be mentioned. First, aseptic technique includes proper hand hygiene and skin sterilization, which are essential measures to reduce cutaneous colonization of the insertion site and reduce the risk of CLABSIs.79 In a systematic review and meta-analysis of eight studies including over 4,000 catheter insertions, skin antisepsis with chlorhexidine was associated with a 50% reduction in CLABSIs compared with povidone iodine.11 Therefore, a chlorhexidine-containing solution is recommended for skin preparation prior to CVC insertion per guidelines by Healthcare Infection Control Practices Advisory Committee/CDC, Society for Healthcare Epidemiology of America/Infectious Diseases Society of America, and American Society of Anesthesiologists.11,69,80,81 Second, maximal sterile barrier precautions refer to the use of sterile gowns, sterile gloves, caps, masks covering both the mouth and nose, and sterile full-body patient drapes. Use of maximal sterile barrier precautions during CVC insertion has been shown to reduce the incidence of CLABSIs compared to standard precautions.26,79,82-84 Third, catheters containing antimicrobial agents may be considered for hospital units with higher CLABSI rates than institutional goals, despite a comprehensive preventive strategy, and may be considered in specific patient populations at high risk of severe complications from a CLABSI.11,69,80 Finally, providers should use a standardized procedure set-up when inserting CVCs to reduce the risk of CLABSIs. The operator should confirm availability and proper functioning of ultrasound equipment prior to commencing a vascular access procedure. Use of all-inclusive procedure carts or kits with sterile ultrasound probe covers, sterile gel, catheter kits, and other necessary supplies is recommended to minimize interruptions during the procedure, and can ultimately reduce the risk of CLABSIs by ensuring maintenance of a sterile field during the procedure.13
12. We recommend that providers should use real-time ultrasound guidance for internal jugular vein catheterization, which reduces the risk of mechanical and infectious complications, the number of needle passes, and time to cannulation and increases overall procedure success rates.
Rationale: The use of real-time ultrasound guidance for CVC insertion has repeatedly demonstrated better outcomes compared to a landmark-based approach in adults.13 Several randomized controlled studies have demonstrated that real-time ultrasound guidance for IJV cannulation reduces the risk of procedure-related mechanical and infectious complications, and improves first-pass and overall success rates in diverse care settings.27,29,45,50,53,65,75,85-90 Mechanical complications that are reduced with ultrasound guidance include pneumothorax and carotid artery puncture.4,5,45,46,53,62,75,86-93 Currently, several medical societies strongly recommend the use of ultrasound guidance during insertion of IJV CVCs.10-12,14,94-96
A meta-analysis by Hind et al. that included 18 randomized controlled studies demonstrated use of real-time ultrasound guidance reduced failure rates (RR 0.14, 95% CI 0.06 to 0.33; P < .0001), increased first-attempt success rates (RR 0.59, 95% CI 0.39 to 0.88; P = .009), reduced complication rates (RR 0.43, 95% CI 0.22 to 0.87; P = .02) and reduced procedure time (P < .0001), compared to a traditional landmark-based approach when inserting IJV CVCs.5
A Cochrane systematic review compared ultrasound-guided versus landmark-based approaches for IJV CVC insertion and found use of real-time ultrasound guidance reduced total complication rates by 71% (RR 0.29, 95% CI 0.17 to 0.52; P < .0001), arterial puncture rates by 72% (RR 0.28, 95% CI 0.18 to 0.44; P < .00001), and rates of hematoma formation by 73% (RR 0.27, 95% CI 0.13 to 0.55; P = .0004). Furthermore, the number of attempts for successful cannulation was reduced (mean difference -1.19 attempts, 95% CI -1.45 to -0.92; P < .00001), the chance of successful insertion on the first attempt was increased by 57% (RR 1.57, 95% CI 1.36 to 1.82; P < .00001), and overall procedure success rates were modestly increased in all groups by 12% (RR 1.12, 95% CI 1.08 to 1.17; P < .00001).46
An important consideration in performing ultrasound guidance is provider experience. A prospective observational study of patients undergoing elective CVC insertion demonstrated higher complication rates for operators that were inexperienced (25.2%) versus experienced (13.6%).54 A randomized controlled study comparing experts and novices with or without the use of ultrasound guidance for IJV CVC insertion demonstrated higher success rates among expert operators and with the use of ultrasound guidance. Among novice operators, the complication rates were lower with the use of ultrasound guidance.97 One study evaluated the procedural success and complication rates of a two-physician technique with one physician manipulating the transducer and another inserting the needle for IJV CVC insertion. This study concluded that procedural success rates and frequency of complications were directly affected by the experience of the physician manipulating the transducer and not by the experience of the physician inserting the needle.98
The impact of ultrasound guidance on improving procedural success rates and reducing complication rates is greatest in patients that are obese, short necked, hypovolemic, or uncooperative.93 Several studies have demonstrated fewer needle passes and decreased time to cannulation compared to the landmark technique in these populations.46,49,53,86-88,92,93
Ultrasound-guided placement of IJV catheters can safely be performed in patients with disorders of hemostasis and those with multiple previous catheter insertions in the same vein.9 Ultrasound-guided placement of CVCs in patients with disorders of hemostasis is safe with high success and low complication rates. In a case series of liver patients with coagulopathy (mean INR 2.17 ± 1.16, median platelet count 150K), the use of ultrasound guidance for CVC insertion was highly successful with no major bleeding complications.99
A study of renal failure patients found high success rates and low complication rates in the patients with a history of multiple previous catheterizations, poor compliance, skeletal deformities, previous failed cannulations, morbid obesity, and disorders of hemostasis.100 A prospective observational study of 200 ultrasound-guided CVC insertions for apheresis showed a 100% success rate with a 92% first-pass success rate.101
The use of real-time ultrasound guidance for IJV CVC insertion has been shown to be cost effective by reducing procedure-related mechanical complications and improving procedural success rates. A companion cost-effectiveness analysis estimated that for every 1,000 patients, 90 complications would be avoided, with a net cost savings of approximately $3,200 using 2002 prices.102
13. We recommend that providers who routinely insert subclavian vein CVCs should use real-time ultrasound guidance, which has been shown to reduce the risk of mechanical complications and number of needle passes and increase overall procedure success rates compared with landmark-based techniques.
Rationale: In clinical practice, the term ultrasound-guided subclavian vein CVC insertion is commonly used. However, the needle insertion site is often lateral to the first rib and providers are technically inserting the CVC in the axillary vein. The subclavian vein becomes the axillary vein at the lateral border of the first rib where the cephalic vein branches from the subclavian vein. To be consistent with common medical parlance, we use the phrase ultrasound-guided subclavian vein CVC insertion in this document.
Advantages of inserting CVCs in the subclavian vein include reliable surface anatomical landmarks for vein location, patient comfort, and lower risk of infection.103 Several observational studies have demonstrated the technique for ultrasound-guided subclavian vein CVC insertion is feasible and safe.104-107 In a large retrospective observational study of ultrasound-guided central venous access among a complex patient group, the majority of patients were cannulated successfully and safely. The subset of patients undergoing axillary vein CVC insertion (n = 1,923) demonstrated a low rate of complications (0.7%), proving it is a safe and effective alternative to the IJV CVC insertion.107
A Cochrane review of ultrasound-guided subclavian vein cannulation (nine studies, 2,030 participants, 2,049 procedures), demonstrated that real-time two-dimensional ultrasound guidance reduced the risk of inadvertent arterial punctures (three studies, 498 participants, RR 0.21, 95% CI 0.06 to 0.82; P = .02) and hematoma formation (three studies, 498 participants, RR 0.26, 95% CI 0.09 to 0.76; P = .01).46 A systematic review and meta-analysis of 10 randomized controlled studies comparing ultrasound-guided versus landmark-based subclavian vein CVC insertion demonstrated a reduction in the risk of arterial punctures, hematoma formation, pneumothorax, and failed catheterization with the use of ultrasound guidance.105
A randomized controlled study comparing ultrasound-guided vs landmark-based approaches to subclavian vein cannulation found that use of ultrasound guidance had a higher success rate (92% vs 44%, P = .0003), fewer minor complications (1 vs 11, P = .002), fewer attempts (1.4 vs 2.5, P = .007) and fewer catheter kits used (1.0 vs 1.4, P = .0003) per cannulation.108
Fragou et al. randomized patients undergoing subclavian vein CVC insertion to a long-axis approach versus a landmark-based approach and found a significantly higher success rate (100% vs 87.5%, P < .05) and lower rates of mechanical complications: artery puncture (0.5% vs 5.4%), hematoma (1.5% vs 5.4%), hemothorax (0% vs 4.4%), pneumothorax (0% vs 4.9%), brachial plexus injury (0% vs 2.9%), phrenic nerve injury (0% vs 1.5%), and cardiac tamponade (0% vs 0.5%).109 The average time to obtain access and the average number of insertion attempts (1.1 ± 0.3 vs 1.9 ± 0.7, P < .05) were significantly reduced in the ultrasound group compared to the landmark-based group.95
A retrospective review of subclavian vein CVC insertions using a supraclavicular approach found no reported complications with the use of ultrasound guidance vs 23 mechanical complications (8 pneumothorax, 15 arterial punctures) with a landmark-based approach.106 However, it is important to note that a supraclavicular approach is not commonly used in clinical practice.
14. We recommend that providers should use real-time ultrasound guidance for femoral venous access, which has been shown to reduce the risk of arterial punctures and total procedure time and increase overall procedure success rates.
Rationale: Anatomy of the femoral region varies, and close proximity or overlap of the femoral vein and artery is common.51 Early studies showed that ultrasound guidance for femoral vein CVC insertion reduced arterial punctures compared with a landmark-based approach (7% vs 16%), reduced total procedure time (55 ± 19 vs 79 ± 62 seconds), and increased procedure success rates (100% vs 90%).52 A Cochrane review that pooled data from four randomized studies comparing ultrasound-guided vs landmark-based femoral vein CVC insertion found higher first-attempt success rates with the use of ultrasound guidance (RR 1.73, 95% CI 1.34 to 2.22; P < .0001) and a small increase in the overall procedure success rates (RR 1.11, 95% CI 1.00 to 1.23; P = .06). There was no difference in inadvertent arterial punctures or other complications.110
Peripheral Venous Access Techniques
15. We recommend that providers should use real-time ultrasound guidance for the insertion of peripherally inserted central catheters (PICCs), which is associated with higher procedure success rates and may be more cost effective compared with landmark-based techniques.
Rationale: Several studies have demonstrated that providers who use ultrasound guidance vs landmarks for PICC insertion have higher procedural success rates, lower complication rates, and lower total placement costs. A prospective observational report of 350 PICC insertions using ultrasound guidance reported a 99% success rate with an average of 1.2 punctures per insertion and lower total costs.20 A retrospective observational study of 500 PICC insertions by designated specialty nurses revealed an overall success rate of 95%, no evidence of phlebitis, and only one CLABSI among the catheters removed.21 A retrospective observational study comparing several PICC variables found higher success rates (99% vs 77%) and lower thrombosis rates (2% vs 9%) using ultrasound guidance vs landmarks alone.22 A study by Robinson et al. demonstrated that having a dedicated PICC team equipped with ultrasound increased their institutional insertion success rates from 73% to 94%.111
A randomized controlled study comparing ultrasound-guided versus landmark-based PICC insertion found high success rates with both techniques (100% vs 96%). However, there was a reduction in the rate of unplanned catheter removals (4.0% vs 18.7%; P = .02), mechanical phlebitis (0% vs 22.9%; P < .001), and venous thrombosis (0% vs 8.3%; P = .037), but a higher rate of catheter migration (32% vs 2.1%; P < .001). Compared with the landmark-based group, the ultrasound-guided group had significantly lower incidence of severe contact dermatitis (P = .038), and improved comfort and costs up to 3 months after PICC placement (P < .05).112
Routine postprocedure chest x-ray (CXR) is generally considered unnecessary if the PICC is inserted with real-time ultrasound guidance along with use of a newer tracking devices, like the magnetic navigation system with intracardiac electrodes.9 Ultrasound can also be used to detect malpositioning of a PICC immediately after completing the procedure. A randomized controlled study comparing ultrasound versus postprocedure CXR detected one malpositioned PICC in the ultrasound group versus 11 in the control group. This study suggested that ultrasound can detect malpositioning immediately postprocedure and reduce the need for a CXR and the possibility of an additional procedure to reposition a catheter.113
16. We recommend that providers should use real-time ultrasound guidance for the placement of peripheral intravenous lines (PIV) in patients with difficult peripheral venous access to reduce the total procedure time, needle insertion attempts, and needle redirections. Ultrasound-guided PIV insertion is also an effective alternative to CVC insertion in patients with difficult venous access.
Rationale: Difficult venous access refers to patients that have had two unsuccessful attempts at PIV insertion using landmarks or a history of difficult access (i.e. edema, obesity, intravenous drug use, chemotherapy, diabetes, hypovolemia, chronic illness, vasculopathy, multiple prior hospitalizations). A meta-analysis of seven randomized controlled studies concluded that ultrasound guidance increases the likelihood of successful PIV insertion (pooled OR 2.42, 95% CI 1.26 to 4.68; P < .008).18 A second meta-analysis that pooled data from seven studies (six randomized controlled studies) confirmed that ultrasound guidance improves success rates of PIV insertion (OR 3.96, 95% CI 1.75 to 8.94).19 Approximately half of these studies had physician operators while the other half had nurse operators.
In one prospective observational study of emergency department patients with two failed attempts of landmark-based PIV insertion, ultrasound guidance with a modified-Seldinger technique showed a relatively high success rate (96%), fewer needle sticks (mean 1.32 sticks, 95% CI 1.12 to 1.52), and shorter time to obtain access (median time 68 seconds).114 Other prospective observational studies have demonstrated that ultrasound guidance for PIV insertion has a high success rate (87%),115 particularly with brachial or basilic veins PIV insertion, among patients with difficult PIV access, defined as having had ≥2 failed attempts.58
Since insertion of PIVs with ultrasound guidance has a high success rate, there is potential to reduce the reliance on CVC insertion for venous access only. In a study of patients that had had two failed attempts at PIV insertion based on landmarks, a PIV was successfully inserted with ultrasound guidance in 84% of patients, obviating the need for CVC placement for venous access.116 A prospective observational study showed ultrasound-guided PIV insertion was an effective alternative to CVC placement in ED patients with difficult venous access with only 1% of patients requiring a CVC.117 Use of ultrasound by nurses for PIV placement has also been shown to reduce the time to obtain venous access, improve patient satisfaction, and reduce the need for physician intervention.118 In a prospective observational study of patients with difficult access, the majority of patients reported a better experience with ultrasound-guided PIV insertion compared to previous landmark-based attempts with an average satisfaction score of 9.2/10 with 76% of patients rating the experience a 10.119 A strong recommendation has been made for use of ultrasound guidance in patients with difficult PIV placement by la Société Française d’Anesthésie et de Réanimation (The French Society of Anesthesia and Resuscitation).95
17. We suggest using real-time ultrasound guidance to reduce the risk of vascular, infectious, and neurological complications during PIV insertion, particularly in patients with difficult venous access.
Rationale: The incidence of complications from PIV insertion is often underestimated. Vascular complications include arterial puncture, hematoma formation, local infiltration or extravasation of fluid, and superficial or deep venous thrombosis. The most common infectious complications with PIV insertion are phlebitis and cellulitis.120 One observational study reported PIV complications occurring in approximately half of all patients with the most common complications being phlebitis, hematoma formation, and fluid/blood leakage.121
A retrospective review of ICU patients who underwent ultrasound-guided PIV insertion by a single physician showed high success rates (99%) with low rates of phlebitis/cellulitis (0.7%).There was an assumed benefit of risk reduction due to the patients no longer requiring a CVC after successful PIV placement.122 Another study found very low rates of infection with both landmark-based and ultrasound-guided PIV placement performed by emergency department nurses, suggesting that there is no increased risk of infection with the use of ultrasound.123 To reduce the risk of infection from PIV insertion, we recommend the use of sterile gel and sterile transducer cover (See Recommendation 2).
Arterial Access Techniques
18. We recommend that providers should use real-time ultrasound guidance for arterial access, which has been shown to increase first-pass success rates, reduce the time to cannulation, and reduce the risk of hematoma development compared with landmark-based techniques.
Rationale: Several randomized controlled studies have assessed the value of ultrasound in arterial catheter insertion. Shiver et al. randomized 60 patients admitted to a tertiary center emergency department to either palpation or ultrasound-guided arterial cannulation. They demonstrated a first-pass success rate of 87% in the ultrasound group compared with 50% in the landmark technique group. In the same study, the use of ultrasound was also associated with reduced time needed to establish arterial access and a 43% reduction in the development of hematoma at the insertion site.124 Levin et al. demonstrated a first-pass success rate of 62% using ultrasound versus 34% by palpation alone in 69 patients requiring intraoperative invasive hemodynamic monitoring.125 Additional randomized controlled studies have demonstrated that ultrasound guidance increases first-attempt success rates compared to traditional palpation.23,126,127
19. We recommend that providers should use real-time ultrasound guidance for femoral arterial access, which has been shown to increase first-pass success rates and reduce the risk of vascular complications.
Rationale: Although it is a less frequently used site, the femoral artery may be accessed for arterial blood sampling or invasive hemodynamic monitoring, and use of ultrasound guidance has been shown to improve the first-pass success rates of femoral artery cannulation. It is important to note that most of these studies comparing ultrasound-guided vs landmark-based femoral artery cannulation were performed in patients undergoing diagnostic or interventional vascular procedures.
A meta-analysis of randomized controlled studies comparing ultrasound-guided vs landmark-based femoral artery catheterization found use of ultrasound guidance was associated with a 49% reduction in overall complications (RR 0.51, 95% CI 0.28 to 0.91; P > .05) and 42% improvement in first-pass success rates.128 In another study, precise site selection with ultrasound was associated with fewer pseudoaneurysms in patients undergoing femoral artery cannulation by ultrasound guidance vs palpation for cardiac catheterization (3% vs 5%, P < .05).129
A multicenter randomized controlled study comparing ultrasound vs fluoroscopic guidance for femoral artery catheterization demonstrated ultrasound guidance improved rates of common femoral artery (CFA) cannulation in patients with high CFA bifurcations (83% vs 70%, P < .01).130 Furthermore, ultrasound guidance improved first-pass success rates (83% vs 46%, P < .0001), reduced number of attempts (1.3 vs 3.0, P < .0001), reduced risk of venipuncture (2.4% vs 15.8%, P < .0001), and reduced median time to obtain access (136 seconds vs148 seconds, P = .003). Vascular complications occurred in fewer patients in the ultrasound vs fluoroscopy groups (1.4% vs 3.4% P = .04). Reduced risk of hematoma formation with routine use of ultrasound guidance was demonstrated in one retrospective observational study (RR 0.62, 95% CI 0.46 to 0.84; P < .01).131
20. We recommend that providers should use real-time ultrasound guidance for radial arterial access, which has been shown to increase first-pass success rates, reduce the time to successful cannulation, and reduce the risk of complications compared with landmark-based techniques.
Rationale: Ultrasound guidance is particularly useful for radial artery cannulation in patients with altered anatomy, obesity, nonpulsatile blood flow, low perfusion, and previously unsuccessful cannulation attempts using a landmark-guided approach.132
A multicenter randomized controlled study that was not included in the abovementioned meta-analyses showed similar benefits of using ultrasound guidance vs landmarks for radial artery catheterization: a reduction in the number of attempts with ultrasound guidance (1.65 ± 1.2 vs 3.05 ± 3.4, P < .0001) and time to obtain access (88 ± 78 vs 108 ± 112 seconds, P = .006), and increased first-pass success rates (65% vs 44%, P < .0001). The use of ultrasound guidance was found to be particularly useful in patients with difficult access by palpation alone.135
Regarding the level of expertise required to use ultrasound guidance, a prospective observational study demonstrated that physicians with little previous ultrasound experience were able to improve their first-attempt success rates and procedure time for radial artery cannulation compared to historical data of landmark-based insertions.136
Postprocedure
21. We recommend that post-procedure pneumothorax should be ruled out by the detection of bilateral lung sliding using a high-frequency linear transducer before and after insertion of internal jugular and subclavian vein CVCs.
Rationale: Detection of lung sliding with two-dimensional ultrasound rules out pneumothorax, and disappearance of lung sliding in an area where it was previously seen is a strong predictor of postprocedure pneumothorax. In a study of critically ill patients, the disappearance of lung sliding was observed in 100% of patients with pneumothorax vs 8.8% of patients without pneumothorax. For detection of pneumothorax, lung sliding showed a sensitivity of 95%, specificity of 91%, and negative predictive value of 100% (P < .001).137 Another study by the same author showed that the combination of horizontal artifacts (absence of comet-tail artifact) and absence of lung sliding had a sensitivity of 100%, specificity of 96.5%, and negative predictive value of 100% for the detection of pneumothorax.138 A meta-analysis of 10 studies on the diagnostic accuracy of CVC confirmation with bedside ultrasound vs chest radiography reported detection of all 12 pneumothoraces with ultrasound, whereas chest radiography missed two pneumothoraces. The pooled sensitivity and specificity of ultrasound for the detection of pneumothorax was 100%, although an imperfect gold standard bias likely affected the results. An important advantage of bedside ultrasound is the ability to rule out pneumothorax immediately after the procedure while at the bedside. The mean time for confirmation of CVC placement with bedside ultrasound was 6 minutes versus 64 minutes and 143 minutes for completion and interpretation of a chest radiograph, respectively.139
22. We recommend that providers should use ultrasound with rapid infusion of agitated saline to visualize a right atrial swirl sign (RASS) for detecting catheter tip misplacement during CVC insertion. The use of RASS to detect the catheter tip may be considered an advanced skill that requires specific training and expertise.
Rationale: Bedside echocardiography is a reliable tool to detect catheter tip misplacement during CVC insertion. In one study, catheter misplacement was detected by bedside echocardiography with a sensitivity of 96% and specificity of 83% (positive predictive value 98%, negative predictive value 55%) and prevented distal positioning of the catheter tip.140 A prospective observational study assessed for RASS, which is turbulent flow in the right atrium after a rapid saline flush of the distal CVC port, to exclude catheter malposition. In this study with 135 CVC placements, visualization of RASS with ultrasound was able to identify all correct CVC placements and three of four catheter misplacements. Median times to complete the ultrasound exam vs CXR were 1 vs 20 minutes, respectively, with a median difference of 24 minutes (95% CI 19.6 to 29.3, P < .0001) between the two techniques.141
A prospective observational study assessed the ability of bedside transthoracic echocardiography to detect the guidewire, microbubbles, or both, in the right atrium compared to transesophageal echocardiography as the gold standard. Bedside transthoracic echocardiography allowed visualization of the right atrium in 94% of patients, and both microbubbles plus guidewire in 91% of patients.142 Hence, bedside transthoracic echocardiography allows adequate visualization of the right atrium. Another prospective observational study combining ultrasonography and contrast enhanced RASS resulted in 96% sensitivity and 93% specificity for the detection of a misplaced catheter, and the concordance with chest radiography was 96%.143
Training
23. To reduce the risk of mechanical and infectious complications, we recommend that novice providers should complete a systematic training program that includes a combination of simulation-based practice, supervised insertion on patients, and evaluation by an expert operator before attempting ultrasound-guided CVC insertion independently on patients.
Rationale: Cumulative experience has been recognized to not be a proxy for mastery of a clinical skill.144 The National Institute for Clinical Excellence (NICE) has recommended that providers performing ultrasound-guided CVC insertion should receive appropriate training to achieve competence before performing the procedure independently.7 Surveys have demonstrated that lack of training is a commonly reported barrier for not using ultrasound.145,146
Structured training programs on CVC insertion have been shown to reduce the occurrence of infectious and mechanical complications.74,143,147-149 The use of ultrasound and checklists, bundling of supplies, and practice with simulation models, as a part of a structured training program, can improve patient safety related to CVC insertion.9,140,150-154
Simulation-based practice has been used in medical education to provide deliberate practice and foster skill development in a controlled learning environment.155-158 Studies have shown transfer of skills demonstrated in a simulated environment to clinical practice, which can improve CVC insertion practices.159,160 Simulation accelerates learning of all trainees, especially novice trainees, and mitigates risks to patients by allowing trainees to achieve a minimal level of competence before attempting the procedure on real patients.152,161,162 Residents that have been trained using simulation preferentially select the IJV site,147 and more reliably use ultrasound to guide their CVC insertions.160,163
Additionally, simulation-based practice allows exposure to procedures and scenarios that may occur infrequently in clinical practice.
Although there is evidence on efficacy of simulation-based CVC training programs, there is no broadly accepted consensus on timing, duration, and content of CVC training programs for trainees or physicians in practice. The minimum recommended technical skills a trainee must master include the ability to (1) manipulate the ultrasound machine to produce a high-quality image to identify the target vessel, (2) advance the needle under direct visualization to the desired target site and depth, (3) deploy the catheter into the target vessel and confirm catheter placement in the target vessel using ultrasound, and (4) ensure the catheter has not been inadvertently placed in an unintended vessel or structure.153
A variety of simulation models are currently used to practice CVC insertion at the most common sites: the internal jugular, subclavian, basilic, and brachial veins.164,165 Effective simulation models should contain vessels that mimic normal anatomy with muscles, soft tissues, and bones. Animal tissue models, such as turkey or chicken breasts, may be effective for simulated practice of ultrasound-guided CVC insertion.166,167 Ultrasound-guided CVC training using human cadavers has also been shown to be effective.168
24. We recommend that cognitive training in ultrasound-guided CVC insertion should include basic anatomy, ultrasound physics, ultrasound machine knobology, fundamentals of image acquisition and interpretation, detection and management of procedural complications, infection prevention strategies, and pathways to attain competency.
Rationale: After receiving training in ultrasound-guided CVC insertion, physicians report significantly higher comfort with the use of ultrasound compared to those who have not received such training.145 Learners find training sessions worthwhile to increase skill levels,167 and skills learned from simulation-based mastery learning programs have been retained up to one year.158
Several commonalities have been noted across training curricula. Anatomy and physiology didactics should include vessel anatomy (location, size, and course);9 vessel differentiation by ultrasound;9,69 blood flow dynamics;69 Virchow’s triad;69 skin integrity and colonization;150 peripheral nerve identification and distribution;9 respiratory anatomy;9,69 upper and lower extremity, axillary, neck, and chest anatomy.9,69 Vascular anatomy is an essential curricular component that may help avoid preventable CVC insertion complications, such as inadvertent nerve, artery, or lung puncture.150,169 Training curricula should also include ultrasound physics (piezoelectric effect, frequency, resolution, attenuation, echogenicity, Doppler ultrasound, arterial and venous flow characteristics), image acquisition and optimization (imaging mode, focus, dynamic range, probe types), and artifacts (reverberation, mirror, shadowing, enhancement).
CVC-related infections are an important cause of morbidity and mortality in the acute and long-term care environment.69 Infection and thrombosis can both be impacted by the insertion site selection, skin integrity, and catheter–vein ratio.2,3,84 Inexperience generally leads to more insertion attempts that can increase trauma during CVC insertion and potentially increase the risk of infections.170 To reduce the risk of infectious complications, training should include important factors to consider in site selection and maintenance of a sterile environment during CVC insertion, including use of maximal sterile barrier precautions, hand hygiene, and appropriate use of skin antiseptic solutions.
Professional society guidelines have been published with recommendations of appropriate techniques for ultrasound-guided vascular access that include training recommendations.9,154 Training should deconstruct the insertion procedure into readily understood individual steps, and can be aided by demonstration of CVC insertion techniques using video clips. An alternative to face-to-face training is internet-based training that has been shown to be as effective as traditional teaching methods in some medical centers.171 Additional methods to deliver cognitive instruction include textbooks, continuing medical education courses, and digital videos.164,172
25. We recommend that trainees should demonstrate minimal competence before placing ultrasound-guided CVCs independently. A minimum number of CVC insertions may inform this determination, but a proctored assessment of competence is most important.
Rationale: CVC catheter placement carries the risk of serious complications including arterial injury or dissection, pneumothorax, or damage to other local structures; arrhythmias; catheter malposition; infection; and thrombosis. Although there is a lack of consensus and high-quality evidence for the certification of skills to perform ultrasound-guided CVC insertion, recommendations have been published advocating for formal and comprehensive training programs in ultrasound-guided CVC insertion with an emphasis on expert supervision prior to independent practice.9,153,154 Two groups of expert operators have recommended that training should include at least 8-10 supervised ultrasound-guided CVC insertions.154,173,174 A consensus task force from the World Congress of Vascular Access has recommended a minimum of six to eight hours of didactic education, four hours of hands-on training on simulation models, and six hours of hands-on ultrasound training on human volunteers to assess normal anatomy.175 This training should be followed by supervised ultrasound-guided CVC insertions until the learner has demonstrated minimal competence with a low rate of complications.35 There is general consensus that arbitrary numbers should not be the sole determinant of competence, and that the most important determinant of competence should be an evaluation by an expert operator.176
26. We recommend that didactic and hands-on training for trainees should coincide with anticipated times of increased performance of vascular access procedures. Refresher training sessions should be offered periodically.
Rationale: Simulation-based CVC training courses have shown a rapid improvement in skills, but lack of practice leads to deterioration of technical skills.161,162,177,178 Thus, a single immersive training session is insufficient to achieve and maintain mastery of skills, and an important factor to acquire technical expertise is sustained, deliberate practice with feedback.179 Furthermore, an insidious decay in skills may go unrecognized as a learner’s comfort and self-confidence does not always correlate with actual performance, leading to increased risk of errors and potential for procedural complications.147,158,180-183 Given the decay in technical skills over time, simulation-based training sessions are most effective when they occur in close temporal proximity to times when those skills are most likely to be used; for example, a simulation-based training session for trainees may be most effective just before the start of a critical care rotation.152 Regularly scheduled training sessions with monitoring and feedback by expert operators can reinforce procedural skills and prevent decay. Some experts have recommended that a minimum of 10 ultrasound-guided CVC insertions should be performed annually to maintain proficiency.153
27. We recommend that competency assessments should include formal evaluation of knowledge and technical skills using standardized assessment tools.
Rationale: Hospitalists and other healthcare providers that place vascular access catheters should undergo competency assessments proctored by an expert operator to verify that they have the required knowledge and skills.184,185 Knowledge competence can be partially evaluated using a written assessment, such as a multiple-choice test, assessing the provider’s cognitive understanding of the procedure.175 For ultrasound-guided CVC insertion, a written examination should be administered in conjunction with an ultrasound image assessment to test the learner’s recognition of normal vs abnormal vascular anatomy. Minimum passing standards should be established a priori according to local or institutional standards.
The final skills assessment should be objective, and the learner should be required to pass all critical steps of the procedure. Failure of the final skills assessment should lead to continued practice with supervision until the learner can consistently demonstrate correct performance of all critical steps. Checklists are commonly used to rate the technical performance of learners because they provide objective criteria for evaluation, can identify specific skill deficiencies, and can determine a learner’s readiness to perform procedures independently.186,187 The administration of skills assessments and feedback methods should be standardized across faculty. Although passing scores on both knowledge and skills assessments do not guarantee safe performance of a procedure independently, they provide a metric to ensure that a minimum level of competence has been achieved before allowing learners to perform procedures on patients without supervision.188
Competency assessments are a recommended component of intramural and extramural certification of skills in ultrasound-guided procedures. Intramural certification pathways differ by institution and often require additional resources including ultrasound machine(s), simulation equipment, and staff time, particularly when simulation-based assessments are incorporated into certification pathways. We recognize that some of these recommendations may not be feasible in resource-limited settings, such as rural hospitals. However, initial and ongoing competency assessments can be performed during routine performance of procedures on patients. For an in-depth review of credentialing pathways for ultrasound-guided bedside procedures, we recommend reviewing the SHM Position Statement on Credentialing of Hospitalists in Ultrasound-Guided Bedside Procedures.24
28. We recommend that competency assessments should evaluate for proficiency in the following knowledge and skills of CVC insertion:
a. Knowledge of the target vein anatomy, proper vessel identification, and recognition of anatomical variants
b. Demonstration of CVC insertion with no technical errors based on a procedural checklist
c. Recognition and management of acute complications, including emergency management of life-threatening complications
d. Real-time needle tip tracking with ultrasound and cannulation on the first attempt in at least five consecutive simulations.
Rationale: Recommendations have been published with the minimal knowledge and skills learners must demonstrate to perform ultrasound-guided vascular access procedures. These include operation of an ultrasound machine to produce high-quality images of the target vessel, tracking of the needle tip with real-time ultrasound guidance, and recognition and understanding of the management of procedural complications.154,175
First, learners must be able to perform a preprocedural assessment of the target vein, including size and patency of the vein; recognition of adjacent critical structures; and recognition of normal anatomical variants.175,189 Second, learners must be able to demonstrate proficiency in tracking the needle tip penetrating the target vessel, inserting the catheter into the target vessel, and confirming catheter placement in the target vessel with ultrasound.154,175 Third, learners must be able to demonstrate recognition of acute complications, including arterial puncture, hematoma formation, and development of pneumothorax.154,175 Trainees should be familiar with recommended evaluation and management algorithms, including indications for emergent consultation.190
29. We recommend a periodic proficiency assessments of all operators should be conducted to ensure maintenance of competency.
Rationale: Competency extends to periodic assessment and not merely an initial evaluation at the time of training.191 Periodic competency assessments should include assessment of proficiency of all providers that perform a procedure, including instructors and supervisors. Supervising providers should maintain their competency in CVC insertion through routine use of their skills in clinical practice.175 An observational study of emergency medicine residents revealed that lack of faculty comfort with ultrasound hindered the residents’ use of ultrasound.192 Thus, there is a need to examine best practices for procedural supervision of trainees because providers are often supervising procedures that they are not comfortable performing on their own.193
KNOWLEDGE GAPS
The process of producing this position statement revealed areas of uncertainty and important gaps in the literature regarding the use of ultrasound guidance for central and peripheral venous access and arterial access.
This position statement recommends a preprocedural ultrasound evaluation of blood vessels based on evidence that providers may detect anatomic anomalies, thrombosis, or vessel stenosis. Ultrasound can also reveal unsuspected high-risk structures in near proximity to the procedure site. Although previous studies have shown that providers can accurately assess vessels with ultrasound for these features, further study is needed to evaluate the effect of a standardized preprocedural ultrasound exam on clinical and procedural decision-making, as well as procedural outcomes.
Second, two ultrasound applications that are being increasingly used but have not been widely implemented are the use of ultrasound to evaluate lung sliding postprocedure to exclude pneumothorax and the verification of central line placement using a rapid infusion of agitated saline to visualize the RASS.139-141 Both of these applications have the potential to expedite postprocedure clearance of central lines for usage and decrease patient radiation exposure by obviating the need for postprocedure CXRs. Despite the supporting evidence, both of these applications are not yet widely used, as few providers have been trained in these techniques which may be considered advanced skills.
Third, despite advances in our knowledge of effective training for vascular access procedures, there is limited agreement on how to define procedural competence. Notable advancements in training include improved understanding of systematic training programs, development of techniques for proctoring procedures, definition of elements for hands-on assessments, and definition of minimum experience needed to perform vascular access procedures independently. However, application of these concepts to move learners toward independent practice remains variably interpreted at different institutions, likely due to limited resources, engrained cultures about procedures, and a lack of national standards. The development of hospitalist-based procedure services at major academic medical centers with high training standards, close monitoring for quality assurance, and the use of databases to track clinical outcomes may advance our understanding and delivery of optimal procedural training.
Finally, ultrasound technology is rapidly evolving which will affect training, techniques, and clinical outcomes in coming years. Development of advanced imaging software with artificial intelligence can improve needle visualization and tracking. These technologies have the potential to facilitate provider training in real-time ultrasound-guided procedures and improve the overall safety of procedures. Emergence of affordable, handheld ultrasound devices is improving access to ultrasound technology, but their role in vascular access procedures is yet to be defined. Furthermore, availability of wireless handheld ultrasound technology and multifrequency transducers will create new possibilities for use of ultrasound in vascular access procedures.
CONCLUSION
We have presented several evidence-based recommendations on the use of ultrasound guidance for placement of central and peripheral vascular access catheters that are intended for hospitalists and other healthcare providers who routinely perform vascular access procedures. By allowing direct visualization of the needle tip and target vessel, the use of ultrasound guidance has been shown in randomized studies to reduce needle insertion attempts, reduce needle redirections, and increase overall procedure success rates. The accuracy of ultrasound to identify the target vessel, assess for thrombosis, and detect anatomical anomalies is superior to that of physical examination. Hospitalists can attain competence in performing ultrasound-guided vascular access procedures through systematic training programs that combine didactic and hands-on training, which optimally include patient-based competency assessments.
Acknowledgments
The authors thank all the members of the Society of Hospital Medicine Point-of-care Ultrasound Task Force and the Education Committee members for their time and dedication to develop these guidelines.
Collaborators of Society of Hospital Medicine Point-of-care Ultrasound Task Force: Robert Arntfield, Jeffrey Bates, Anjali Bhagra, Michael Blaivas, Daniel Brotman, Richard Hoppmann, Susan Hunt, Trevor P. Jensen, Venkat Kalidindi, Ketino Kobaidze, Joshua Lenchus, Paul Mayo, Satyen Nichani, Vicki Noble, Nitin Puri, Aliaksei Pustavoitau, Kreegan Reierson, Gerard Salame, Kirk Spencer, Vivek Tayal, David Tierney
SHM Point-of-care Ultrasound Task Force: CHAIRS: Nilam J. Soni, Ricardo Franco-Sadud, Jeff Bates. WORKING GROUPS: Thoracentesis Working Group: Ria Dancel (chair), Daniel Schnobrich, Nitin Puri. Vascular Access Working Group: Ricardo Franco (chair), Benji Mathews, Saaid Abdel-Ghani, Sophia Rodgers, Martin Perez, Daniel Schnobrich. Paracentesis Working Group: Joel Cho (chair), Benji Mathews, Kreegan Reierson, Anjali Bhagra, Trevor P. Jensen Lumbar Puncture Working Group: Nilam J. Soni (chair), Ricardo Franco, Gerard Salame, Josh Lenchus, Venkat Kalidindi, Ketino Kobaidze. Credentialing Working Group: Brian P Lucas (chair), David Tierney, Trevor P. Jensen PEER REVIEWERS: Robert Arntfield, Michael Blaivas, Richard Hoppmann, Paul Mayo, Vicki Noble, Aliaksei Pustavoitau, Kirk Spencer, Vivek Tayal. METHODOLOGIST: Mahmoud El-Barbary. LIBRARIAN: Loretta Grikis. SOCIETY OF HOSPITAL MEDICINE EDUCATION COMMITTEE: Daniel Brotman (past chair), Satyen Nichani (current chair), Susan Hunt. SOCIETY OF HOSPITAL MEDICINE STAFF: Nick Marzano.
Disclaimer
The contents of this publication do not represent the views of the U.S. Department of Veterans Affairs or the United States Government.
Approximately five million central venous catheters (CVCs) are inserted in the United States annually, with over 15 million catheter days documented in intensive care units alone.1 Traditional CVC insertion techniques using landmarks are associated with a high risk of mechanical complications, particularly pneumothorax and arterial puncture, which occur in 5%-19% patients.2,3
Since the 1990s, several randomized controlled studies and meta-analyses have demonstrated that the use of real-time ultrasound guidance for CVC insertion increases procedure success rates and decreases mechanical complications.4,5 Use of real-time ultrasound guidance was recommended by the Agency for Healthcare Research and Quality, the Institute of Medicine, the National Institute for Health and Care Excellence, the Centers for Disease Control and Prevention, and several medical specialty societies in the early 2000s.6-14 Despite these recommendations, ultrasound guidance has not been universally adopted. Currently, an estimated 20%-55% of CVC insertions in the internal jugular vein are performed without ultrasound guidance.15-17
Following the emergence of literature supporting the use of ultrasound guidance for CVC insertion, observational and randomized controlled studies demonstrated improved procedural success rates with the use of ultrasound guidance for the insertion of peripheral intravenous lines (PIVs), arterial catheters, and peripherally inserted central catheters (PICCs).18-23
The purpose of this position statement is to present evidence-based recommendations on the use of ultrasound guidance for the insertion of central and peripheral vascular access catheters in adult patients. This document presents consensus-based recommendations with supporting evidence for clinical outcomes, techniques, and training for the use of ultrasound guidance for vascular access. We have subdivided the recommendations on techniques for central venous access, peripheral venous access, and arterial access individually, as some providers may not perform all types of vascular access procedures.
These recommendations are intended for hospitalists and other healthcare providers that routinely place central and peripheral vascular access catheters in acutely ill patients. However, this position statement does not mandate that all hospitalists should place central or peripheral vascular access catheters given the diverse array of hospitalist practice settings. For training and competency assessments, we recognize that some of these recommendations may not be feasible in resource-limited settings, such as rural hospitals, where equipment and staffing for assessments are not available. Recommendations and frameworks for initial and ongoing credentialing of hospitalists in ultrasound-guided bedside procedures have been previously published in an Society of Hospital Medicine (SHM) position statement titled, “Credentialing of Hospitalists in Ultrasound-Guided Bedside Procedures.”24
METHODS
Detailed methods are described in Appendix 1. The SHM Point-of-care Ultrasound (POCUS) Task Force was assembled to carry out this guideline development project under the direction of the SHM Board of Directors, Director of Education, and Education Committee. All expert panel members were physicians or advanced practice providers with expertise in POCUS. Expert panel members were divided into working group members, external peer reviewers, and a methodologist. All Task Force members were required to disclose any potential conflicts of interest (Appendix 2). The literature search was conducted in two independent phases. The first phase included literature searches conducted by the vascular access working group members themselves. Key clinical questions and draft recommendations were then prepared. A systematic literature search was conducted by a medical librarian based on the findings of the initial literature search and draft recommendations. The Medline, Embase, CINAHL, and Cochrane medical databases were searched from 1975 to December 2015 initially. Google Scholar was also searched without limiters. An updated search was conducted in November 2017. The literature search strings are included in Appendix 3. All article abstracts were initially screened for relevance by at least two members of the vascular access working group. Full-text versions of screened articles were reviewed, and articles on the use of ultrasound to guide vascular access were selected. The following article types were excluded: non-English language, nonhuman, age <18 years, meeting abstracts, meeting posters, narrative reviews, case reports, letters, and editorials. All relevant systematic reviews, meta-analyses, randomized controlled studies, and observational studies of ultrasound-guided vascular access were screened and selected (Appendix 3, Figure 1). All full-text articles were shared electronically among the working group members, and final article selection was based on working group consensus. Selected articles were incorporated into the draft recommendations.
These recommendations were developed using the Research and Development (RAND) Appropriateness Method that required panel judgment and consensus.14 The 28 voting members of the SHM POCUS Task Force reviewed and voted on the draft recommendations considering five transforming factors: (1) Problem priority and importance, (2) Level of quality of evidence, (3) Benefit/harm balance, (4) Benefit/burden balance, and (5) Certainty/concerns about PEAF (Preferences/Equity/Acceptability/Feasibility). Using an internet-based electronic data collection tool (REDCap™), panel members participated in two rounds of electronic voting, one in August 2018 and the other in October 2018 (Appendix 4). Voting on appropriateness was conducted using a nine-point Likert scale. The three zones of the nine-point Likert scale were inappropriate (1-3 points), uncertain (4-6 points), and appropriate (7-9 points). The degree of consensus was assessed using the RAND algorithm (Appendix 1, Figure 1 and Table 1). Establishing a recommendation required at least 70% agreement that a recommendation was “appropriate.” Disagreement was defined as >30% of panelists voting outside of the zone of the median. A strong recommendation required at least 80% of the votes within one integer of the median per the RAND rules.
Recommendations were classified as strong or weak/conditional based on preset rules defining the panel’s level of consensus, which determined the wording for each recommendation (Table 2). The final version of the consensus-based recommendations underwent internal and external review by members of the SHM POCUS Task Force, the SHM Education Committee, and the SHM Executive Committee. The SHM Executive Committee reviewed and approved this position statement prior to its publication in the Journal of Hospital Medicine.
RESULTS
Literature Search
A total of 5,563 references were pooled from an initial search performed by a certified medical librarian in December 2015 (4,668 citations) which was updated in November 2017 (791 citations), and from the personal bibliographies and searches (104 citations) performed by working group members. A total of 514 full-text articles were reviewed. The final selection included 192 articles that were abstracted into a data table and incorporated into the draft recommendations. See Appendix 3 for details of the literature search strategy.
Recommendations
Four domains (technique, clinical outcomes, training, and knowledge gaps) with 31 draft recommendations were generated based on a review of the literature. Selected references were abstracted and assigned to each draft recommendation. Rationales for each recommendation cite supporting evidence. After two rounds of panel voting, 31 recommendations achieved agreement based on the RAND rules. During the peer review process, two of the recommendations were merged with other recommendations. Thus, a total of 29 recommendations received final approval. The degree of consensus based on the median score and the dispersion of voting around the median are shown in Appendix 5. Twenty-seven statements were approved as strong recommendations, and two were approved as weak/conditional recommendations. The strength of each recommendation and degree of consensus are summarized in Table 3.
Terminology
Central Venous Catheterization
Central venous catheterization refers to insertion of tunneled or nontunneled large bore vascular catheters that are most commonly inserted into the internal jugular, subclavian, or femoral veins with the catheter tip located in a central vein. These vascular access catheters are synonymously referred to as central lines or central venous catheters (CVCs). Nontunneled catheters are designed for short-term use and should be removed promptly when no longer clinically indicated or after a maximum of 14 days.25
Peripherally Inserted Central Catheter (PICC)
Peripherally inserted central catheters, or PICC lines, are inserted most commonly in the basilic or brachial veins in adult patients, and the catheter tip terminates in the distal superior vena cava or cavo-atrial junction. These catheters are designed to remain in place for a duration of several weeks, as long as it is clinically indicated.
Midline Catheterization
Midline catheters are a type of peripheral venous catheter that are an intermediary between a peripheral intravenous catheter and PICC line. Midline catheters are most commonly inserted in the brachial or basilic veins, but unlike PICC lines, the tips of these catheters terminate in the axillary or subclavian vein. Midline catheters are typically 8 cm to 20 cm in length and inserted for a duration <30 days.
Peripheral Intravenous Catheterization
Peripheral intravenous lines (PIV) refer to small bore venous catheters that are most commonly 14G to 24G and inserted into patients for short-term peripheral venous access. Common sites of ultrasound-guided PIV insertion include the superficial and deep veins of the hand, forearm, and arm.
Arterial Catheterization
Arterial catheters are commonly used for reliable blood pressure monitoring, frequent arterial blood
RECOMMENDATIONS
Preprocedure
1. We recommend that providers should be familiar with the operation of their specific ultrasound machine prior to initiation of a vascular access procedure.
Rationale: There is strong consensus that providers must be familiar with the knobs and functions of the specific make and model of ultrasound machine that will be utilized for a vascular access procedure. Minimizing adjustments to the ultrasound machine during the procedure may reduce the risk of contaminating the sterile field.
2. We recommend that providers should use a high-frequency linear transducer with a sterile sheath and sterile gel to perform vascular access procedures.
Rationale: High-frequency linear-array transducers are recommended for the vast majority of vascular access procedures due to their superior resolution compared to other transducer types. Both central and peripheral vascular access procedures, including PIV, PICC, and arterial line placement, should be performed using sterile technique. A sterile transducer cover and sterile gel must be utilized, and providers must be trained in sterile preparation of the ultrasound transducer.13,26,27
The depth of femoral vessels correlates with body mass index (BMI). When accessing these vessels in a morbidly obese patient with a thigh circumference >60 cm and vessel depth >8 cm, a curvilinear transducer may be preferred for its deeper penetration.28 For patients who are poor candidates for bedside insertion of vascular access catheters, such as uncooperative patients, patients with atypical vascular anatomy or poorly visualized target vessels, we recommend consultation with a vascular access specialist prior to attempting the procedure.
3. We recommend that providers should use two-dimensional ultrasound to evaluate for anatomical variations and absence of vascular thrombosis during preprocedural site selection.
Rationale: A thorough ultrasound examination of the target vessel is warranted prior to catheter placement. Anatomical variations that may affect procedural decision-making are easily detected with ultrasound. A focused vascular ultrasound examination is particularly important in patients who have had temporary or tunneled venous catheters, which can cause stenosis or thrombosis of the target vein.
For internal jugular vein (IJV) CVCs, ultrasound is useful for visualizing the relationship between the IJV and common carotid artery (CCA), particularly in terms of vessel overlap. Furthermore, ultrasound allows for immediate revisualization upon changes in head position.29-32 Troianos et al. found >75% overlap of the IJV and CCA in 54% of all patients and in 64% of older patients (age >60 years) whose heads were rotated to the contralateral side.30 In one study of IJV CVC insertion, inadvertent carotid artery punctures were reduced (3% vs 10%) with the use of ultrasound guidance vs landmarks alone.33 In a cohort of 64 high-risk neurosurgical patients, cannulation success was 100% with the use of ultrasound guidance, and there were no injuries to the carotid artery, even though the procedure was performed with a 30-degree head elevation and anomalous IJV anatomy in 39% of patients.34 In a prospective, randomized controlled study of 1,332 patients, ultrasound-guided cannulation in a neutral position was demonstrated to be as safe as the 45-degree rotated position.35
Ultrasound allows for the recognition of anatomical variations which may influence the selection of the vascular access site or technique. Benter et al. found that 36% of patients showed anatomical variations in the IJV and surrounding tissue.36 Similarly Caridi showed the anatomy of the right IJV to be atypical in 29% of patients,37 and Brusasco found that 37% of bariatric patients had anatomical variations of the IJV.38 In a study of 58 patients, there was significant variability in the IJV position and IJV diameter, ranging from 0.5 cm to >2 cm.39 In a study of hemodialysis patients, 75% of patients had sonographic venous abnormalities that led to a change in venous access approach.40
To detect acute or chronic upper extremity deep venous thrombosis or stenosis, two-dimensional visualization with compression should be part of the ultrasound examination prior to central venous catheterization. In a study of patients that had undergone CVC insertion 9-19 weeks earlier, 50% of patients had an IJV thrombosis or stenosis leading to selection of an alternative site. In this study, use of ultrasound for a preprocedural site evaluation reduced unnecessary attempts at catheterizing an occluded vein.41 At least two other studies demonstrated an appreciable likelihood of thrombosis. In a study of bariatric patients, 8% of patients had asymptomatic thrombosis38 and in another study, 9% of patients being evaluated for hemodialysis catheter placement had asymptomatic IJV thrombosis.37
4. We recommend that providers should evaluate the target blood vessel size and depth during a preprocedural ultrasound evaluation.
Rationale: The size, depth, and anatomic location of central veins can vary considerably. These features are easily discernable using ultrasound. Contrary to traditional teaching, the IJV is located 1 cm anterolateral to the CCA in only about two-thirds of patients.37,39,42,43 Furthermore, the diameter of the IJV can vary significantly, ranging from 0.5 cm to >2 cm.39 The laterality of blood vessels may vary considerably as well. A preprocedural ultrasound evaluation of contralateral subclavian and axillary veins showed a significant absolute difference in cross-sectional area of 26.7 mm2 (P < .001).42
Blood vessels can also shift considerably when a patient is in the Trendelenburg position. In one study, the IJV diameter changed from 11.2 (± 1.5) mm to 15.4 (± 1.5) mm in the supine versus the Trendelenburg position at 15 degrees.33 An observational study demonstrated a frog-legged position with reverse Trendelenburg increased the femoral vein size and reduced the common surface area with the common femoral artery compared to a neutral position. Thus, a frog-legged position with reverse Trendelenburg position may be preferred, since overall catheterization success rates are higher in this position.44
Techniques
General Techniques
5. We recommend that providers should avoid using static ultrasound alone to mark the needle insertion site for vascular access procedures.
Rationale: The use of static ultrasound guidance to mark a needle insertion site is not recommended because normal anatomical relationships of vessels vary, and site marking can be inaccurate with minimal changes in patient position, especially of the neck.43,45,46 Benefits of using ultrasound guidance for vascular access are attained when ultrasound is used to track the needle tip in real-time as it is advanced toward the target vessel.
Although continuous-wave Doppler ultrasound without two-dimensional visualization was used in the past, it is no longer recommended for IJV CVC insertion.47 In a study that randomized patients to IJV CVC insertion with continuous-wave Doppler alone vs two-dimensional ultrasound guidance, the use of two-dimensional ultrasound guidance showed significant improvement in first-pass success rates (97% vs 91%, P = .045), particularly in patients with BMI >30 (97% vs 77%, P = .011).48
A randomized study comparing real-time ultrasound-guided, landmark-based, and ultrasound-marked techniques found higher success rates in the real-time ultrasound-guided group than the other two groups (100% vs 74% vs 73%, respectively; P = .01). The total number of mechanical complications was higher in the landmark-based and ultrasound-marked groups than in the real-time ultrasound-guided group (24% and 36% versus 0%, respectively; P = .01).49 Another randomized controlled study found higher success rates with real-time ultrasound guidance (98%) versus an ultrasound-marked (82%) or landmark-based (64%) approach for central line placement.50
6. We recommend that providers should use real-time (dynamic), two-dimensional ultrasound guidance with a high-frequency linear transducer for CVC insertion, regardless of the provider’s level of experience.
7. We suggest using either a transverse (short-axis) or longitudinal (long-axis) approach when performing real-time ultrasound-guided vascular access procedures.
Rationale: In clinical practice, the phrases transverse, short-axis, or out-of-plane approach are synonymous, as are longitudinal, long-axis, and in-plane approach. The short-axis approach involves tracking the needle tip as it approximates the target vessel with the ultrasound beam oriented in a transverse plane perpendicular to the target vessel. The target vessel is seen as a circular structure on the ultrasound screen as the needle tip approaches the target vessel from above. This approach is also called the out-of-plane technique since the needle passes through the ultrasound plane. The advantages of the short-axis approach include better visualization of adjacent vessels or nerves and the relative ease of skill acquisition for novice operators.9 When using the short-axis approach, extra care must be taken to track the needle tip from the point of insertion on the skin to the target vessel. A disadvantage of the short-axis approach is unintended posterior wall puncture of the target vessel.55
In contrast to a short-axis approach, a long-axis approach is performed with the ultrasound beam aligned parallel to the vessel. The vessel appears as a long tubular structure and the entire needle is visualized as it traverses across the ultrasound screen to approach the target vessel. The long-axis approach is also called an in-plane technique because the needle is maintained within the plane of the ultrasound beam. The advantage of a long-axis approach is the ability to visualize the entire needle as it is inserted into the vessel.14 A randomized crossover study with simulation models compared a long-axis versus short-axis approach for both IJV and subclavian vein catheterization. This study showed decreased number of needle redirections (relative risk (RR) 0.5, 95% confidence interval (CI) 0.3 to 0.7), and posterior wall penetrations (OR 0.3, 95% CI 0.1 to 0.9) using a long-axis versus short-axis approach for subclavian vein catheterization.56
A randomized controlled study comparing a long-axis or short-axis approach with ultrasound versus a landmark-based approach for IJV CVC insertion showed higher success rates (100% vs 90%; P < .001), lower insertion time (53 vs 116 seconds; P < .001), and fewer attempts to obtain access (2.5 vs 1.2 attempts, P < .001) with either the long- or short-axis ultrasound approach. The average time to obtain access and number of attempts were comparable between the short-axis and long-axis approaches with ultrasound. The incidence of carotid puncture and hematoma was significantly higher with the landmark-based approach versus either the long- or short-axis ultrasound approach (carotid puncture 17% vs 3%, P = .024; hematoma 23% vs 3%, P = .003).57
High success rates have been reported using a short-axis approach for insertion of PIV lines.58 A prospective, randomized trial compared the short-axis and long-axis approach in patients who had had ≥2 failed PIV insertion attempts. Success rate was 95% (95% CI, 0.85 to 1.00) in the short-axis group compared with 85% (95% CI, 0.69 to 1.00) in the long-axis group. All three subjects with failed PIV placement in the long-axis group had successful rescue placement using a short-axis approach. Furthermore, the short-axis approach was faster than the long-axis approach.59
For radial artery cannulation, limited data exist comparing the short- and long-axis approaches. A randomized controlled study compared a long-axis vs short-axis ultrasound approach for radial artery cannulation. Although the overall procedure success rate was 100% in both groups, the long-axis approach had higher first-pass success rates (1.27 ± 0.4 vs 1.5 ± 0.5, P < .05), shorter cannulation times (24 ± 17 vs 47 ± 34 seconds, P < .05), fewer hematomas (4% vs 43%, P < .05) and fewer posterior wall penetrations (20% vs 56%, P < .05).60
Another technique that has been described for IJV CVC insertion is an oblique-axis approach, a hybrid between the long- and short-axis approaches. In this approach, the transducer is aligned obliquely over the IJV and the needle is inserted using a long-axis or in-plane approach. A prospective randomized trial compared the short-axis, long-axis, and oblique-axis approaches during IJV cannulation. First-pass success rates were 70%, 52%, and 74% with the short-axis, long-axis, and oblique-axis approaches, respectively, and a statistically significant difference was found between the long- and oblique-axis approaches (P = .002). A higher rate of posterior wall puncture was observed with a short-axis approach (15%) compared with the oblique-axis (7%) and long-axis (4%) approaches (P = .047).61
8. We recommend that providers should visualize the needle tip and guidewire in the target vein prior to vessel dilatation.
Rationale: When real-time ultrasound guidance is used, visualization of the needle tip within the vein is the first step to confirm cannulation of the vein and not the artery. After the guidewire is advanced, the provider can use transverse and longitudinal views to reconfirm cannulation of the vein. In a longitudinal view, the guidewire is readily seen positioned within the vein, entering the anterior wall and lying along the posterior wall of the vein. Unintentional perforation of the posterior wall of the vein with entry into the underlying artery can be detected by ultrasound, allowing prompt removal of the needle and guidewire before proceeding with dilation of the vessel. In a prospective observational study that reviewed ultrasound-guided IJV CVC insertions, physicians were able to more readily visualize the guidewire than the needle in the vein.62 A prospective observational study determined that novice operators can visualize intravascular guidewires in simulation models with an overall accuracy of 97%.63
In a retrospective review of CVC insertions where the guidewire position was routinely confirmed in the target vessel prior to dilation, there were no cases of arterial dilation, suggesting confirmation of guidewire position can potentially eliminate the morbidity and mortality associated with arterial dilation during CVC insertion.64
9. To increase the success rate of ultrasound-guided vascular access procedures, we recommend that providers should utilize echogenic needles, plastic needle guides, and/or ultrasound beam steering when available.
Rationale: Echogenic needles have ridged tips that appear brighter on the screen, allowing for better visualization of the needle tip. Plastic needle guides help stabilize the needle alongside the transducer when using either a transverse or longitudinal approach. Although evidence is limited, some studies have reported higher procedural success rates when using echogenic needles, plastic needle guides, and ultrasound beam steering software. In a prospective observational study, Augustides et al. showed significantly higher IJV cannulation rates with versus without use of a needle guide after first (81% vs 69%, P = .0054) and second (93% vs 80%. P = .0001) needle passes.65 A randomized study by Maecken et al. compared subclavian vein CVC insertion with or without use of a needle guide, and found higher procedure success rates within the first and second attempts, reduced time to obtain access (16 seconds vs 30 seconds; P = .0001) and increased needle visibility (86% vs 32%; P < .0001) with the use of a needle guide.66 Another study comparing a short-axis versus long-axis approach with a needle guide showed improved needle visualization using a long-axis approach with a needle guide.67 A randomized study comparing use of a novel, sled-mounted needle guide to a free-hand approach for venous cannulation in simulation models showed the novel, sled-mounted needle guide improved overall success rates and efficiency of cannulation.68
Central Venous Access Techniques
10. We recommend that providers should use a standardized procedure checklist that includes use of real-time ultrasound guidance to reduce the risk of central line-associated bloodstream infection (CLABSI) from CVC insertion.
Rationale: A standardized checklist or protocol should be developed to ensure compliance with all recommendations for insertion of CVCs. Evidence-based protocols address periprocedural issues, such as indications for CVC, and procedural techniques, such as use of maximal sterile barrier precautions to reduce the risk of infection. Protocols and checklists that follow established guidelines for CVC insertion have been shown to decrease CLABSI rates.69,70 Similarly, development of checklists and protocols for maintenance of central venous catheters have been effective in reducing CLABSIs.71 Although no externally-validated checklist has been universally accepted or endorsed by national safety organizations, a few internally-validated checklists are available through peer-reviewed publications.72,73 An observational educational cohort of internal medicine residents who received training using simulation of the entire CVC insertion process was able to demonstrate fewer CLABSIs after the simulator-trained residents rotated in the intensive care unit (ICU) (0.50 vs 3.2 infections per 1,000 catheter days, P = .001).74
11. We recommend that providers should use real-time ultrasound guidance, combined with aseptic technique and maximal sterile barrier precautions, to reduce the incidence of infectious complications from CVC insertion.
Rationale: The use of real-time ultrasound guidance for CVC placement has demonstrated a statistically significant reduction in CLABSIs compared to landmark-based techniques.75 The Centers for Disease Control and Prevention (CDC) guidelines for the prevention of intravascular catheter-related infections recommend the use of ultrasound guidance to reduce the number of cannulation attempts and risk of mechanical complications.69 A prospective, three-arm study comparing ultrasound-guided long-axis, short-axis, and landmark-based approaches showed a CLABSI rate of 20% in the landmark-based group versus 10% in each of the ultrasound groups.57 Another randomized study comparing use of ultrasound guidance to a landmark-based technique for IJV CVC insertion demonstrated significantly lower CLABSI rates with the use of ultrasound (2% vs 10%; P < .05).72
Studies have shown that a systems-based intervention featuring a standardized catheter kit or catheter bundle significantly reduced CLABSI rates.76-78 A complete review of all preventive measures to reduce the risk of CLABSI is beyond the scope of this review, but a few key points will be mentioned. First, aseptic technique includes proper hand hygiene and skin sterilization, which are essential measures to reduce cutaneous colonization of the insertion site and reduce the risk of CLABSIs.79 In a systematic review and meta-analysis of eight studies including over 4,000 catheter insertions, skin antisepsis with chlorhexidine was associated with a 50% reduction in CLABSIs compared with povidone iodine.11 Therefore, a chlorhexidine-containing solution is recommended for skin preparation prior to CVC insertion per guidelines by Healthcare Infection Control Practices Advisory Committee/CDC, Society for Healthcare Epidemiology of America/Infectious Diseases Society of America, and American Society of Anesthesiologists.11,69,80,81 Second, maximal sterile barrier precautions refer to the use of sterile gowns, sterile gloves, caps, masks covering both the mouth and nose, and sterile full-body patient drapes. Use of maximal sterile barrier precautions during CVC insertion has been shown to reduce the incidence of CLABSIs compared to standard precautions.26,79,82-84 Third, catheters containing antimicrobial agents may be considered for hospital units with higher CLABSI rates than institutional goals, despite a comprehensive preventive strategy, and may be considered in specific patient populations at high risk of severe complications from a CLABSI.11,69,80 Finally, providers should use a standardized procedure set-up when inserting CVCs to reduce the risk of CLABSIs. The operator should confirm availability and proper functioning of ultrasound equipment prior to commencing a vascular access procedure. Use of all-inclusive procedure carts or kits with sterile ultrasound probe covers, sterile gel, catheter kits, and other necessary supplies is recommended to minimize interruptions during the procedure, and can ultimately reduce the risk of CLABSIs by ensuring maintenance of a sterile field during the procedure.13
12. We recommend that providers should use real-time ultrasound guidance for internal jugular vein catheterization, which reduces the risk of mechanical and infectious complications, the number of needle passes, and time to cannulation and increases overall procedure success rates.
Rationale: The use of real-time ultrasound guidance for CVC insertion has repeatedly demonstrated better outcomes compared to a landmark-based approach in adults.13 Several randomized controlled studies have demonstrated that real-time ultrasound guidance for IJV cannulation reduces the risk of procedure-related mechanical and infectious complications, and improves first-pass and overall success rates in diverse care settings.27,29,45,50,53,65,75,85-90 Mechanical complications that are reduced with ultrasound guidance include pneumothorax and carotid artery puncture.4,5,45,46,53,62,75,86-93 Currently, several medical societies strongly recommend the use of ultrasound guidance during insertion of IJV CVCs.10-12,14,94-96
A meta-analysis by Hind et al. that included 18 randomized controlled studies demonstrated use of real-time ultrasound guidance reduced failure rates (RR 0.14, 95% CI 0.06 to 0.33; P < .0001), increased first-attempt success rates (RR 0.59, 95% CI 0.39 to 0.88; P = .009), reduced complication rates (RR 0.43, 95% CI 0.22 to 0.87; P = .02) and reduced procedure time (P < .0001), compared to a traditional landmark-based approach when inserting IJV CVCs.5
A Cochrane systematic review compared ultrasound-guided versus landmark-based approaches for IJV CVC insertion and found use of real-time ultrasound guidance reduced total complication rates by 71% (RR 0.29, 95% CI 0.17 to 0.52; P < .0001), arterial puncture rates by 72% (RR 0.28, 95% CI 0.18 to 0.44; P < .00001), and rates of hematoma formation by 73% (RR 0.27, 95% CI 0.13 to 0.55; P = .0004). Furthermore, the number of attempts for successful cannulation was reduced (mean difference -1.19 attempts, 95% CI -1.45 to -0.92; P < .00001), the chance of successful insertion on the first attempt was increased by 57% (RR 1.57, 95% CI 1.36 to 1.82; P < .00001), and overall procedure success rates were modestly increased in all groups by 12% (RR 1.12, 95% CI 1.08 to 1.17; P < .00001).46
An important consideration in performing ultrasound guidance is provider experience. A prospective observational study of patients undergoing elective CVC insertion demonstrated higher complication rates for operators that were inexperienced (25.2%) versus experienced (13.6%).54 A randomized controlled study comparing experts and novices with or without the use of ultrasound guidance for IJV CVC insertion demonstrated higher success rates among expert operators and with the use of ultrasound guidance. Among novice operators, the complication rates were lower with the use of ultrasound guidance.97 One study evaluated the procedural success and complication rates of a two-physician technique with one physician manipulating the transducer and another inserting the needle for IJV CVC insertion. This study concluded that procedural success rates and frequency of complications were directly affected by the experience of the physician manipulating the transducer and not by the experience of the physician inserting the needle.98
The impact of ultrasound guidance on improving procedural success rates and reducing complication rates is greatest in patients that are obese, short necked, hypovolemic, or uncooperative.93 Several studies have demonstrated fewer needle passes and decreased time to cannulation compared to the landmark technique in these populations.46,49,53,86-88,92,93
Ultrasound-guided placement of IJV catheters can safely be performed in patients with disorders of hemostasis and those with multiple previous catheter insertions in the same vein.9 Ultrasound-guided placement of CVCs in patients with disorders of hemostasis is safe with high success and low complication rates. In a case series of liver patients with coagulopathy (mean INR 2.17 ± 1.16, median platelet count 150K), the use of ultrasound guidance for CVC insertion was highly successful with no major bleeding complications.99
A study of renal failure patients found high success rates and low complication rates in the patients with a history of multiple previous catheterizations, poor compliance, skeletal deformities, previous failed cannulations, morbid obesity, and disorders of hemostasis.100 A prospective observational study of 200 ultrasound-guided CVC insertions for apheresis showed a 100% success rate with a 92% first-pass success rate.101
The use of real-time ultrasound guidance for IJV CVC insertion has been shown to be cost effective by reducing procedure-related mechanical complications and improving procedural success rates. A companion cost-effectiveness analysis estimated that for every 1,000 patients, 90 complications would be avoided, with a net cost savings of approximately $3,200 using 2002 prices.102
13. We recommend that providers who routinely insert subclavian vein CVCs should use real-time ultrasound guidance, which has been shown to reduce the risk of mechanical complications and number of needle passes and increase overall procedure success rates compared with landmark-based techniques.
Rationale: In clinical practice, the term ultrasound-guided subclavian vein CVC insertion is commonly used. However, the needle insertion site is often lateral to the first rib and providers are technically inserting the CVC in the axillary vein. The subclavian vein becomes the axillary vein at the lateral border of the first rib where the cephalic vein branches from the subclavian vein. To be consistent with common medical parlance, we use the phrase ultrasound-guided subclavian vein CVC insertion in this document.
Advantages of inserting CVCs in the subclavian vein include reliable surface anatomical landmarks for vein location, patient comfort, and lower risk of infection.103 Several observational studies have demonstrated the technique for ultrasound-guided subclavian vein CVC insertion is feasible and safe.104-107 In a large retrospective observational study of ultrasound-guided central venous access among a complex patient group, the majority of patients were cannulated successfully and safely. The subset of patients undergoing axillary vein CVC insertion (n = 1,923) demonstrated a low rate of complications (0.7%), proving it is a safe and effective alternative to the IJV CVC insertion.107
A Cochrane review of ultrasound-guided subclavian vein cannulation (nine studies, 2,030 participants, 2,049 procedures), demonstrated that real-time two-dimensional ultrasound guidance reduced the risk of inadvertent arterial punctures (three studies, 498 participants, RR 0.21, 95% CI 0.06 to 0.82; P = .02) and hematoma formation (three studies, 498 participants, RR 0.26, 95% CI 0.09 to 0.76; P = .01).46 A systematic review and meta-analysis of 10 randomized controlled studies comparing ultrasound-guided versus landmark-based subclavian vein CVC insertion demonstrated a reduction in the risk of arterial punctures, hematoma formation, pneumothorax, and failed catheterization with the use of ultrasound guidance.105
A randomized controlled study comparing ultrasound-guided vs landmark-based approaches to subclavian vein cannulation found that use of ultrasound guidance had a higher success rate (92% vs 44%, P = .0003), fewer minor complications (1 vs 11, P = .002), fewer attempts (1.4 vs 2.5, P = .007) and fewer catheter kits used (1.0 vs 1.4, P = .0003) per cannulation.108
Fragou et al. randomized patients undergoing subclavian vein CVC insertion to a long-axis approach versus a landmark-based approach and found a significantly higher success rate (100% vs 87.5%, P < .05) and lower rates of mechanical complications: artery puncture (0.5% vs 5.4%), hematoma (1.5% vs 5.4%), hemothorax (0% vs 4.4%), pneumothorax (0% vs 4.9%), brachial plexus injury (0% vs 2.9%), phrenic nerve injury (0% vs 1.5%), and cardiac tamponade (0% vs 0.5%).109 The average time to obtain access and the average number of insertion attempts (1.1 ± 0.3 vs 1.9 ± 0.7, P < .05) were significantly reduced in the ultrasound group compared to the landmark-based group.95
A retrospective review of subclavian vein CVC insertions using a supraclavicular approach found no reported complications with the use of ultrasound guidance vs 23 mechanical complications (8 pneumothorax, 15 arterial punctures) with a landmark-based approach.106 However, it is important to note that a supraclavicular approach is not commonly used in clinical practice.
14. We recommend that providers should use real-time ultrasound guidance for femoral venous access, which has been shown to reduce the risk of arterial punctures and total procedure time and increase overall procedure success rates.
Rationale: Anatomy of the femoral region varies, and close proximity or overlap of the femoral vein and artery is common.51 Early studies showed that ultrasound guidance for femoral vein CVC insertion reduced arterial punctures compared with a landmark-based approach (7% vs 16%), reduced total procedure time (55 ± 19 vs 79 ± 62 seconds), and increased procedure success rates (100% vs 90%).52 A Cochrane review that pooled data from four randomized studies comparing ultrasound-guided vs landmark-based femoral vein CVC insertion found higher first-attempt success rates with the use of ultrasound guidance (RR 1.73, 95% CI 1.34 to 2.22; P < .0001) and a small increase in the overall procedure success rates (RR 1.11, 95% CI 1.00 to 1.23; P = .06). There was no difference in inadvertent arterial punctures or other complications.110
Peripheral Venous Access Techniques
15. We recommend that providers should use real-time ultrasound guidance for the insertion of peripherally inserted central catheters (PICCs), which is associated with higher procedure success rates and may be more cost effective compared with landmark-based techniques.
Rationale: Several studies have demonstrated that providers who use ultrasound guidance vs landmarks for PICC insertion have higher procedural success rates, lower complication rates, and lower total placement costs. A prospective observational report of 350 PICC insertions using ultrasound guidance reported a 99% success rate with an average of 1.2 punctures per insertion and lower total costs.20 A retrospective observational study of 500 PICC insertions by designated specialty nurses revealed an overall success rate of 95%, no evidence of phlebitis, and only one CLABSI among the catheters removed.21 A retrospective observational study comparing several PICC variables found higher success rates (99% vs 77%) and lower thrombosis rates (2% vs 9%) using ultrasound guidance vs landmarks alone.22 A study by Robinson et al. demonstrated that having a dedicated PICC team equipped with ultrasound increased their institutional insertion success rates from 73% to 94%.111
A randomized controlled study comparing ultrasound-guided versus landmark-based PICC insertion found high success rates with both techniques (100% vs 96%). However, there was a reduction in the rate of unplanned catheter removals (4.0% vs 18.7%; P = .02), mechanical phlebitis (0% vs 22.9%; P < .001), and venous thrombosis (0% vs 8.3%; P = .037), but a higher rate of catheter migration (32% vs 2.1%; P < .001). Compared with the landmark-based group, the ultrasound-guided group had significantly lower incidence of severe contact dermatitis (P = .038), and improved comfort and costs up to 3 months after PICC placement (P < .05).112
Routine postprocedure chest x-ray (CXR) is generally considered unnecessary if the PICC is inserted with real-time ultrasound guidance along with use of a newer tracking devices, like the magnetic navigation system with intracardiac electrodes.9 Ultrasound can also be used to detect malpositioning of a PICC immediately after completing the procedure. A randomized controlled study comparing ultrasound versus postprocedure CXR detected one malpositioned PICC in the ultrasound group versus 11 in the control group. This study suggested that ultrasound can detect malpositioning immediately postprocedure and reduce the need for a CXR and the possibility of an additional procedure to reposition a catheter.113
16. We recommend that providers should use real-time ultrasound guidance for the placement of peripheral intravenous lines (PIV) in patients with difficult peripheral venous access to reduce the total procedure time, needle insertion attempts, and needle redirections. Ultrasound-guided PIV insertion is also an effective alternative to CVC insertion in patients with difficult venous access.
Rationale: Difficult venous access refers to patients that have had two unsuccessful attempts at PIV insertion using landmarks or a history of difficult access (i.e. edema, obesity, intravenous drug use, chemotherapy, diabetes, hypovolemia, chronic illness, vasculopathy, multiple prior hospitalizations). A meta-analysis of seven randomized controlled studies concluded that ultrasound guidance increases the likelihood of successful PIV insertion (pooled OR 2.42, 95% CI 1.26 to 4.68; P < .008).18 A second meta-analysis that pooled data from seven studies (six randomized controlled studies) confirmed that ultrasound guidance improves success rates of PIV insertion (OR 3.96, 95% CI 1.75 to 8.94).19 Approximately half of these studies had physician operators while the other half had nurse operators.
In one prospective observational study of emergency department patients with two failed attempts of landmark-based PIV insertion, ultrasound guidance with a modified-Seldinger technique showed a relatively high success rate (96%), fewer needle sticks (mean 1.32 sticks, 95% CI 1.12 to 1.52), and shorter time to obtain access (median time 68 seconds).114 Other prospective observational studies have demonstrated that ultrasound guidance for PIV insertion has a high success rate (87%),115 particularly with brachial or basilic veins PIV insertion, among patients with difficult PIV access, defined as having had ≥2 failed attempts.58
Since insertion of PIVs with ultrasound guidance has a high success rate, there is potential to reduce the reliance on CVC insertion for venous access only. In a study of patients that had had two failed attempts at PIV insertion based on landmarks, a PIV was successfully inserted with ultrasound guidance in 84% of patients, obviating the need for CVC placement for venous access.116 A prospective observational study showed ultrasound-guided PIV insertion was an effective alternative to CVC placement in ED patients with difficult venous access with only 1% of patients requiring a CVC.117 Use of ultrasound by nurses for PIV placement has also been shown to reduce the time to obtain venous access, improve patient satisfaction, and reduce the need for physician intervention.118 In a prospective observational study of patients with difficult access, the majority of patients reported a better experience with ultrasound-guided PIV insertion compared to previous landmark-based attempts with an average satisfaction score of 9.2/10 with 76% of patients rating the experience a 10.119 A strong recommendation has been made for use of ultrasound guidance in patients with difficult PIV placement by la Société Française d’Anesthésie et de Réanimation (The French Society of Anesthesia and Resuscitation).95
17. We suggest using real-time ultrasound guidance to reduce the risk of vascular, infectious, and neurological complications during PIV insertion, particularly in patients with difficult venous access.
Rationale: The incidence of complications from PIV insertion is often underestimated. Vascular complications include arterial puncture, hematoma formation, local infiltration or extravasation of fluid, and superficial or deep venous thrombosis. The most common infectious complications with PIV insertion are phlebitis and cellulitis.120 One observational study reported PIV complications occurring in approximately half of all patients with the most common complications being phlebitis, hematoma formation, and fluid/blood leakage.121
A retrospective review of ICU patients who underwent ultrasound-guided PIV insertion by a single physician showed high success rates (99%) with low rates of phlebitis/cellulitis (0.7%).There was an assumed benefit of risk reduction due to the patients no longer requiring a CVC after successful PIV placement.122 Another study found very low rates of infection with both landmark-based and ultrasound-guided PIV placement performed by emergency department nurses, suggesting that there is no increased risk of infection with the use of ultrasound.123 To reduce the risk of infection from PIV insertion, we recommend the use of sterile gel and sterile transducer cover (See Recommendation 2).
Arterial Access Techniques
18. We recommend that providers should use real-time ultrasound guidance for arterial access, which has been shown to increase first-pass success rates, reduce the time to cannulation, and reduce the risk of hematoma development compared with landmark-based techniques.
Rationale: Several randomized controlled studies have assessed the value of ultrasound in arterial catheter insertion. Shiver et al. randomized 60 patients admitted to a tertiary center emergency department to either palpation or ultrasound-guided arterial cannulation. They demonstrated a first-pass success rate of 87% in the ultrasound group compared with 50% in the landmark technique group. In the same study, the use of ultrasound was also associated with reduced time needed to establish arterial access and a 43% reduction in the development of hematoma at the insertion site.124 Levin et al. demonstrated a first-pass success rate of 62% using ultrasound versus 34% by palpation alone in 69 patients requiring intraoperative invasive hemodynamic monitoring.125 Additional randomized controlled studies have demonstrated that ultrasound guidance increases first-attempt success rates compared to traditional palpation.23,126,127
19. We recommend that providers should use real-time ultrasound guidance for femoral arterial access, which has been shown to increase first-pass success rates and reduce the risk of vascular complications.
Rationale: Although it is a less frequently used site, the femoral artery may be accessed for arterial blood sampling or invasive hemodynamic monitoring, and use of ultrasound guidance has been shown to improve the first-pass success rates of femoral artery cannulation. It is important to note that most of these studies comparing ultrasound-guided vs landmark-based femoral artery cannulation were performed in patients undergoing diagnostic or interventional vascular procedures.
A meta-analysis of randomized controlled studies comparing ultrasound-guided vs landmark-based femoral artery catheterization found use of ultrasound guidance was associated with a 49% reduction in overall complications (RR 0.51, 95% CI 0.28 to 0.91; P > .05) and 42% improvement in first-pass success rates.128 In another study, precise site selection with ultrasound was associated with fewer pseudoaneurysms in patients undergoing femoral artery cannulation by ultrasound guidance vs palpation for cardiac catheterization (3% vs 5%, P < .05).129
A multicenter randomized controlled study comparing ultrasound vs fluoroscopic guidance for femoral artery catheterization demonstrated ultrasound guidance improved rates of common femoral artery (CFA) cannulation in patients with high CFA bifurcations (83% vs 70%, P < .01).130 Furthermore, ultrasound guidance improved first-pass success rates (83% vs 46%, P < .0001), reduced number of attempts (1.3 vs 3.0, P < .0001), reduced risk of venipuncture (2.4% vs 15.8%, P < .0001), and reduced median time to obtain access (136 seconds vs148 seconds, P = .003). Vascular complications occurred in fewer patients in the ultrasound vs fluoroscopy groups (1.4% vs 3.4% P = .04). Reduced risk of hematoma formation with routine use of ultrasound guidance was demonstrated in one retrospective observational study (RR 0.62, 95% CI 0.46 to 0.84; P < .01).131
20. We recommend that providers should use real-time ultrasound guidance for radial arterial access, which has been shown to increase first-pass success rates, reduce the time to successful cannulation, and reduce the risk of complications compared with landmark-based techniques.
Rationale: Ultrasound guidance is particularly useful for radial artery cannulation in patients with altered anatomy, obesity, nonpulsatile blood flow, low perfusion, and previously unsuccessful cannulation attempts using a landmark-guided approach.132
A multicenter randomized controlled study that was not included in the abovementioned meta-analyses showed similar benefits of using ultrasound guidance vs landmarks for radial artery catheterization: a reduction in the number of attempts with ultrasound guidance (1.65 ± 1.2 vs 3.05 ± 3.4, P < .0001) and time to obtain access (88 ± 78 vs 108 ± 112 seconds, P = .006), and increased first-pass success rates (65% vs 44%, P < .0001). The use of ultrasound guidance was found to be particularly useful in patients with difficult access by palpation alone.135
Regarding the level of expertise required to use ultrasound guidance, a prospective observational study demonstrated that physicians with little previous ultrasound experience were able to improve their first-attempt success rates and procedure time for radial artery cannulation compared to historical data of landmark-based insertions.136
Postprocedure
21. We recommend that post-procedure pneumothorax should be ruled out by the detection of bilateral lung sliding using a high-frequency linear transducer before and after insertion of internal jugular and subclavian vein CVCs.
Rationale: Detection of lung sliding with two-dimensional ultrasound rules out pneumothorax, and disappearance of lung sliding in an area where it was previously seen is a strong predictor of postprocedure pneumothorax. In a study of critically ill patients, the disappearance of lung sliding was observed in 100% of patients with pneumothorax vs 8.8% of patients without pneumothorax. For detection of pneumothorax, lung sliding showed a sensitivity of 95%, specificity of 91%, and negative predictive value of 100% (P < .001).137 Another study by the same author showed that the combination of horizontal artifacts (absence of comet-tail artifact) and absence of lung sliding had a sensitivity of 100%, specificity of 96.5%, and negative predictive value of 100% for the detection of pneumothorax.138 A meta-analysis of 10 studies on the diagnostic accuracy of CVC confirmation with bedside ultrasound vs chest radiography reported detection of all 12 pneumothoraces with ultrasound, whereas chest radiography missed two pneumothoraces. The pooled sensitivity and specificity of ultrasound for the detection of pneumothorax was 100%, although an imperfect gold standard bias likely affected the results. An important advantage of bedside ultrasound is the ability to rule out pneumothorax immediately after the procedure while at the bedside. The mean time for confirmation of CVC placement with bedside ultrasound was 6 minutes versus 64 minutes and 143 minutes for completion and interpretation of a chest radiograph, respectively.139
22. We recommend that providers should use ultrasound with rapid infusion of agitated saline to visualize a right atrial swirl sign (RASS) for detecting catheter tip misplacement during CVC insertion. The use of RASS to detect the catheter tip may be considered an advanced skill that requires specific training and expertise.
Rationale: Bedside echocardiography is a reliable tool to detect catheter tip misplacement during CVC insertion. In one study, catheter misplacement was detected by bedside echocardiography with a sensitivity of 96% and specificity of 83% (positive predictive value 98%, negative predictive value 55%) and prevented distal positioning of the catheter tip.140 A prospective observational study assessed for RASS, which is turbulent flow in the right atrium after a rapid saline flush of the distal CVC port, to exclude catheter malposition. In this study with 135 CVC placements, visualization of RASS with ultrasound was able to identify all correct CVC placements and three of four catheter misplacements. Median times to complete the ultrasound exam vs CXR were 1 vs 20 minutes, respectively, with a median difference of 24 minutes (95% CI 19.6 to 29.3, P < .0001) between the two techniques.141
A prospective observational study assessed the ability of bedside transthoracic echocardiography to detect the guidewire, microbubbles, or both, in the right atrium compared to transesophageal echocardiography as the gold standard. Bedside transthoracic echocardiography allowed visualization of the right atrium in 94% of patients, and both microbubbles plus guidewire in 91% of patients.142 Hence, bedside transthoracic echocardiography allows adequate visualization of the right atrium. Another prospective observational study combining ultrasonography and contrast enhanced RASS resulted in 96% sensitivity and 93% specificity for the detection of a misplaced catheter, and the concordance with chest radiography was 96%.143
Training
23. To reduce the risk of mechanical and infectious complications, we recommend that novice providers should complete a systematic training program that includes a combination of simulation-based practice, supervised insertion on patients, and evaluation by an expert operator before attempting ultrasound-guided CVC insertion independently on patients.
Rationale: Cumulative experience has been recognized to not be a proxy for mastery of a clinical skill.144 The National Institute for Clinical Excellence (NICE) has recommended that providers performing ultrasound-guided CVC insertion should receive appropriate training to achieve competence before performing the procedure independently.7 Surveys have demonstrated that lack of training is a commonly reported barrier for not using ultrasound.145,146
Structured training programs on CVC insertion have been shown to reduce the occurrence of infectious and mechanical complications.74,143,147-149 The use of ultrasound and checklists, bundling of supplies, and practice with simulation models, as a part of a structured training program, can improve patient safety related to CVC insertion.9,140,150-154
Simulation-based practice has been used in medical education to provide deliberate practice and foster skill development in a controlled learning environment.155-158 Studies have shown transfer of skills demonstrated in a simulated environment to clinical practice, which can improve CVC insertion practices.159,160 Simulation accelerates learning of all trainees, especially novice trainees, and mitigates risks to patients by allowing trainees to achieve a minimal level of competence before attempting the procedure on real patients.152,161,162 Residents that have been trained using simulation preferentially select the IJV site,147 and more reliably use ultrasound to guide their CVC insertions.160,163
Additionally, simulation-based practice allows exposure to procedures and scenarios that may occur infrequently in clinical practice.
Although there is evidence on efficacy of simulation-based CVC training programs, there is no broadly accepted consensus on timing, duration, and content of CVC training programs for trainees or physicians in practice. The minimum recommended technical skills a trainee must master include the ability to (1) manipulate the ultrasound machine to produce a high-quality image to identify the target vessel, (2) advance the needle under direct visualization to the desired target site and depth, (3) deploy the catheter into the target vessel and confirm catheter placement in the target vessel using ultrasound, and (4) ensure the catheter has not been inadvertently placed in an unintended vessel or structure.153
A variety of simulation models are currently used to practice CVC insertion at the most common sites: the internal jugular, subclavian, basilic, and brachial veins.164,165 Effective simulation models should contain vessels that mimic normal anatomy with muscles, soft tissues, and bones. Animal tissue models, such as turkey or chicken breasts, may be effective for simulated practice of ultrasound-guided CVC insertion.166,167 Ultrasound-guided CVC training using human cadavers has also been shown to be effective.168
24. We recommend that cognitive training in ultrasound-guided CVC insertion should include basic anatomy, ultrasound physics, ultrasound machine knobology, fundamentals of image acquisition and interpretation, detection and management of procedural complications, infection prevention strategies, and pathways to attain competency.
Rationale: After receiving training in ultrasound-guided CVC insertion, physicians report significantly higher comfort with the use of ultrasound compared to those who have not received such training.145 Learners find training sessions worthwhile to increase skill levels,167 and skills learned from simulation-based mastery learning programs have been retained up to one year.158
Several commonalities have been noted across training curricula. Anatomy and physiology didactics should include vessel anatomy (location, size, and course);9 vessel differentiation by ultrasound;9,69 blood flow dynamics;69 Virchow’s triad;69 skin integrity and colonization;150 peripheral nerve identification and distribution;9 respiratory anatomy;9,69 upper and lower extremity, axillary, neck, and chest anatomy.9,69 Vascular anatomy is an essential curricular component that may help avoid preventable CVC insertion complications, such as inadvertent nerve, artery, or lung puncture.150,169 Training curricula should also include ultrasound physics (piezoelectric effect, frequency, resolution, attenuation, echogenicity, Doppler ultrasound, arterial and venous flow characteristics), image acquisition and optimization (imaging mode, focus, dynamic range, probe types), and artifacts (reverberation, mirror, shadowing, enhancement).
CVC-related infections are an important cause of morbidity and mortality in the acute and long-term care environment.69 Infection and thrombosis can both be impacted by the insertion site selection, skin integrity, and catheter–vein ratio.2,3,84 Inexperience generally leads to more insertion attempts that can increase trauma during CVC insertion and potentially increase the risk of infections.170 To reduce the risk of infectious complications, training should include important factors to consider in site selection and maintenance of a sterile environment during CVC insertion, including use of maximal sterile barrier precautions, hand hygiene, and appropriate use of skin antiseptic solutions.
Professional society guidelines have been published with recommendations of appropriate techniques for ultrasound-guided vascular access that include training recommendations.9,154 Training should deconstruct the insertion procedure into readily understood individual steps, and can be aided by demonstration of CVC insertion techniques using video clips. An alternative to face-to-face training is internet-based training that has been shown to be as effective as traditional teaching methods in some medical centers.171 Additional methods to deliver cognitive instruction include textbooks, continuing medical education courses, and digital videos.164,172
25. We recommend that trainees should demonstrate minimal competence before placing ultrasound-guided CVCs independently. A minimum number of CVC insertions may inform this determination, but a proctored assessment of competence is most important.
Rationale: CVC catheter placement carries the risk of serious complications including arterial injury or dissection, pneumothorax, or damage to other local structures; arrhythmias; catheter malposition; infection; and thrombosis. Although there is a lack of consensus and high-quality evidence for the certification of skills to perform ultrasound-guided CVC insertion, recommendations have been published advocating for formal and comprehensive training programs in ultrasound-guided CVC insertion with an emphasis on expert supervision prior to independent practice.9,153,154 Two groups of expert operators have recommended that training should include at least 8-10 supervised ultrasound-guided CVC insertions.154,173,174 A consensus task force from the World Congress of Vascular Access has recommended a minimum of six to eight hours of didactic education, four hours of hands-on training on simulation models, and six hours of hands-on ultrasound training on human volunteers to assess normal anatomy.175 This training should be followed by supervised ultrasound-guided CVC insertions until the learner has demonstrated minimal competence with a low rate of complications.35 There is general consensus that arbitrary numbers should not be the sole determinant of competence, and that the most important determinant of competence should be an evaluation by an expert operator.176
26. We recommend that didactic and hands-on training for trainees should coincide with anticipated times of increased performance of vascular access procedures. Refresher training sessions should be offered periodically.
Rationale: Simulation-based CVC training courses have shown a rapid improvement in skills, but lack of practice leads to deterioration of technical skills.161,162,177,178 Thus, a single immersive training session is insufficient to achieve and maintain mastery of skills, and an important factor to acquire technical expertise is sustained, deliberate practice with feedback.179 Furthermore, an insidious decay in skills may go unrecognized as a learner’s comfort and self-confidence does not always correlate with actual performance, leading to increased risk of errors and potential for procedural complications.147,158,180-183 Given the decay in technical skills over time, simulation-based training sessions are most effective when they occur in close temporal proximity to times when those skills are most likely to be used; for example, a simulation-based training session for trainees may be most effective just before the start of a critical care rotation.152 Regularly scheduled training sessions with monitoring and feedback by expert operators can reinforce procedural skills and prevent decay. Some experts have recommended that a minimum of 10 ultrasound-guided CVC insertions should be performed annually to maintain proficiency.153
27. We recommend that competency assessments should include formal evaluation of knowledge and technical skills using standardized assessment tools.
Rationale: Hospitalists and other healthcare providers that place vascular access catheters should undergo competency assessments proctored by an expert operator to verify that they have the required knowledge and skills.184,185 Knowledge competence can be partially evaluated using a written assessment, such as a multiple-choice test, assessing the provider’s cognitive understanding of the procedure.175 For ultrasound-guided CVC insertion, a written examination should be administered in conjunction with an ultrasound image assessment to test the learner’s recognition of normal vs abnormal vascular anatomy. Minimum passing standards should be established a priori according to local or institutional standards.
The final skills assessment should be objective, and the learner should be required to pass all critical steps of the procedure. Failure of the final skills assessment should lead to continued practice with supervision until the learner can consistently demonstrate correct performance of all critical steps. Checklists are commonly used to rate the technical performance of learners because they provide objective criteria for evaluation, can identify specific skill deficiencies, and can determine a learner’s readiness to perform procedures independently.186,187 The administration of skills assessments and feedback methods should be standardized across faculty. Although passing scores on both knowledge and skills assessments do not guarantee safe performance of a procedure independently, they provide a metric to ensure that a minimum level of competence has been achieved before allowing learners to perform procedures on patients without supervision.188
Competency assessments are a recommended component of intramural and extramural certification of skills in ultrasound-guided procedures. Intramural certification pathways differ by institution and often require additional resources including ultrasound machine(s), simulation equipment, and staff time, particularly when simulation-based assessments are incorporated into certification pathways. We recognize that some of these recommendations may not be feasible in resource-limited settings, such as rural hospitals. However, initial and ongoing competency assessments can be performed during routine performance of procedures on patients. For an in-depth review of credentialing pathways for ultrasound-guided bedside procedures, we recommend reviewing the SHM Position Statement on Credentialing of Hospitalists in Ultrasound-Guided Bedside Procedures.24
28. We recommend that competency assessments should evaluate for proficiency in the following knowledge and skills of CVC insertion:
a. Knowledge of the target vein anatomy, proper vessel identification, and recognition of anatomical variants
b. Demonstration of CVC insertion with no technical errors based on a procedural checklist
c. Recognition and management of acute complications, including emergency management of life-threatening complications
d. Real-time needle tip tracking with ultrasound and cannulation on the first attempt in at least five consecutive simulations.
Rationale: Recommendations have been published with the minimal knowledge and skills learners must demonstrate to perform ultrasound-guided vascular access procedures. These include operation of an ultrasound machine to produce high-quality images of the target vessel, tracking of the needle tip with real-time ultrasound guidance, and recognition and understanding of the management of procedural complications.154,175
First, learners must be able to perform a preprocedural assessment of the target vein, including size and patency of the vein; recognition of adjacent critical structures; and recognition of normal anatomical variants.175,189 Second, learners must be able to demonstrate proficiency in tracking the needle tip penetrating the target vessel, inserting the catheter into the target vessel, and confirming catheter placement in the target vessel with ultrasound.154,175 Third, learners must be able to demonstrate recognition of acute complications, including arterial puncture, hematoma formation, and development of pneumothorax.154,175 Trainees should be familiar with recommended evaluation and management algorithms, including indications for emergent consultation.190
29. We recommend a periodic proficiency assessments of all operators should be conducted to ensure maintenance of competency.
Rationale: Competency extends to periodic assessment and not merely an initial evaluation at the time of training.191 Periodic competency assessments should include assessment of proficiency of all providers that perform a procedure, including instructors and supervisors. Supervising providers should maintain their competency in CVC insertion through routine use of their skills in clinical practice.175 An observational study of emergency medicine residents revealed that lack of faculty comfort with ultrasound hindered the residents’ use of ultrasound.192 Thus, there is a need to examine best practices for procedural supervision of trainees because providers are often supervising procedures that they are not comfortable performing on their own.193
KNOWLEDGE GAPS
The process of producing this position statement revealed areas of uncertainty and important gaps in the literature regarding the use of ultrasound guidance for central and peripheral venous access and arterial access.
This position statement recommends a preprocedural ultrasound evaluation of blood vessels based on evidence that providers may detect anatomic anomalies, thrombosis, or vessel stenosis. Ultrasound can also reveal unsuspected high-risk structures in near proximity to the procedure site. Although previous studies have shown that providers can accurately assess vessels with ultrasound for these features, further study is needed to evaluate the effect of a standardized preprocedural ultrasound exam on clinical and procedural decision-making, as well as procedural outcomes.
Second, two ultrasound applications that are being increasingly used but have not been widely implemented are the use of ultrasound to evaluate lung sliding postprocedure to exclude pneumothorax and the verification of central line placement using a rapid infusion of agitated saline to visualize the RASS.139-141 Both of these applications have the potential to expedite postprocedure clearance of central lines for usage and decrease patient radiation exposure by obviating the need for postprocedure CXRs. Despite the supporting evidence, both of these applications are not yet widely used, as few providers have been trained in these techniques which may be considered advanced skills.
Third, despite advances in our knowledge of effective training for vascular access procedures, there is limited agreement on how to define procedural competence. Notable advancements in training include improved understanding of systematic training programs, development of techniques for proctoring procedures, definition of elements for hands-on assessments, and definition of minimum experience needed to perform vascular access procedures independently. However, application of these concepts to move learners toward independent practice remains variably interpreted at different institutions, likely due to limited resources, engrained cultures about procedures, and a lack of national standards. The development of hospitalist-based procedure services at major academic medical centers with high training standards, close monitoring for quality assurance, and the use of databases to track clinical outcomes may advance our understanding and delivery of optimal procedural training.
Finally, ultrasound technology is rapidly evolving which will affect training, techniques, and clinical outcomes in coming years. Development of advanced imaging software with artificial intelligence can improve needle visualization and tracking. These technologies have the potential to facilitate provider training in real-time ultrasound-guided procedures and improve the overall safety of procedures. Emergence of affordable, handheld ultrasound devices is improving access to ultrasound technology, but their role in vascular access procedures is yet to be defined. Furthermore, availability of wireless handheld ultrasound technology and multifrequency transducers will create new possibilities for use of ultrasound in vascular access procedures.
CONCLUSION
We have presented several evidence-based recommendations on the use of ultrasound guidance for placement of central and peripheral vascular access catheters that are intended for hospitalists and other healthcare providers who routinely perform vascular access procedures. By allowing direct visualization of the needle tip and target vessel, the use of ultrasound guidance has been shown in randomized studies to reduce needle insertion attempts, reduce needle redirections, and increase overall procedure success rates. The accuracy of ultrasound to identify the target vessel, assess for thrombosis, and detect anatomical anomalies is superior to that of physical examination. Hospitalists can attain competence in performing ultrasound-guided vascular access procedures through systematic training programs that combine didactic and hands-on training, which optimally include patient-based competency assessments.
Acknowledgments
The authors thank all the members of the Society of Hospital Medicine Point-of-care Ultrasound Task Force and the Education Committee members for their time and dedication to develop these guidelines.
Collaborators of Society of Hospital Medicine Point-of-care Ultrasound Task Force: Robert Arntfield, Jeffrey Bates, Anjali Bhagra, Michael Blaivas, Daniel Brotman, Richard Hoppmann, Susan Hunt, Trevor P. Jensen, Venkat Kalidindi, Ketino Kobaidze, Joshua Lenchus, Paul Mayo, Satyen Nichani, Vicki Noble, Nitin Puri, Aliaksei Pustavoitau, Kreegan Reierson, Gerard Salame, Kirk Spencer, Vivek Tayal, David Tierney
SHM Point-of-care Ultrasound Task Force: CHAIRS: Nilam J. Soni, Ricardo Franco-Sadud, Jeff Bates. WORKING GROUPS: Thoracentesis Working Group: Ria Dancel (chair), Daniel Schnobrich, Nitin Puri. Vascular Access Working Group: Ricardo Franco (chair), Benji Mathews, Saaid Abdel-Ghani, Sophia Rodgers, Martin Perez, Daniel Schnobrich. Paracentesis Working Group: Joel Cho (chair), Benji Mathews, Kreegan Reierson, Anjali Bhagra, Trevor P. Jensen Lumbar Puncture Working Group: Nilam J. Soni (chair), Ricardo Franco, Gerard Salame, Josh Lenchus, Venkat Kalidindi, Ketino Kobaidze. Credentialing Working Group: Brian P Lucas (chair), David Tierney, Trevor P. Jensen PEER REVIEWERS: Robert Arntfield, Michael Blaivas, Richard Hoppmann, Paul Mayo, Vicki Noble, Aliaksei Pustavoitau, Kirk Spencer, Vivek Tayal. METHODOLOGIST: Mahmoud El-Barbary. LIBRARIAN: Loretta Grikis. SOCIETY OF HOSPITAL MEDICINE EDUCATION COMMITTEE: Daniel Brotman (past chair), Satyen Nichani (current chair), Susan Hunt. SOCIETY OF HOSPITAL MEDICINE STAFF: Nick Marzano.
Disclaimer
The contents of this publication do not represent the views of the U.S. Department of Veterans Affairs or the United States Government.
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164. Bayci AW, Mangla J, Jenkins CS, Ivascu FA, Robbins JM. Novel educational module for subclavian central venous catheter insertion using real-time ultrasound guidance. J Surg Educ. 2015;72(6):1217-1223. https://doi.org/10.1016/j.jsurg.2015.07.010.
165. Andreatta P, Chen Y, Marsh M, Cho K. Simulation-based training improves applied clinical placement of ultrasound-guided PICCs. Support Care Cancer Off J Multinat Assoc Support Care Cancer. 2011;19(4):539-543. https://doi.org/10.1007/s00520-010-0849-2.
166. Rosen BT, Uddin PQ, Harrington AR, Ault BW, Ault MJ. Does personalized vascular access training on a nonhuman tissue model allow for learning and retention of central line placement skills? Phase II of the procedural patient safety initiative (PPSI-II). J Hosp Med. 2009;4(7):423-429. https://doi.org/10.1002/jhm.571.
167. Ault MJ, Rosen BT, Ault B. The use of tissue models for vascular access training. Phase I of the procedural patient safety initiative. J Gen Intern Med. 2006;21(5):514-517. https://doi.org/10.1111/j.1525-1497.2006.00440.x.
168. Varga S, Smith J, Minneti M, et al. Central venous catheterization using a perfused human cadaveric model: application to surgical education. J Surg Educ. 2015;72(1):28-32. https://doi.org/10.1016/j.jsurg.2014.07.005.
169. Sansivero GE. Venous anatomy and physiology. Considerations for vascular access device placement and function. J Intraven Nurs Off Publ Intraven Nurs Soc. 1998;21(5 Suppl):S107-S114.
170. Eisen LA, Narasimhan M, Berger JS, et al. Mechanical complications of central venous catheters. Journal of intensive care medicine. 2006;21(1):40-46. https://doi.org/10.1177/0885066605280884.
171. Chenkin J, Lee S, Huynh T, Bandiera G. Procedures can be learned on the Web: a randomized study of ultrasound-guided vascular access training. Acad Emerg Med. 2008;15(10):949-954. https://doi.org/10.1111/j.1553-2712.2008.00231.x.
172. Abualenain J, Calabrese K, Tansek R, Ranniger C. 319 Comparing standard versus video-based teaching for ultrasound-guided internal jugular central venous catheter access for fourth-year medical students. Ann Emerg Med. 2014;64(4):S113. https://doi.org/10.1016/j.annemergmed.2014.07.347.
173. Pustavoitau A, Blaivas M, Brown SM, et al. Recommendations for achieving and maintaining competence and credentialing in critical care ultrasound with focused cardiac ultrasound and advanced critical care echocardiography. Crit Care Med. 2016.
174. Jensen TP, Soni NJ, Tierney DM, Lucas BP. Hospital privileging practices for bedside procedures: A survey of hospitalist experts. J Hosp Med. 2017;12(10):836-839. https://doi.org/10.12788/jhm.2837.
175. Moureau N, Lamperti M, Kelly LJ, et al. Evidence-based consensus on the insertion of central venous access devices: definition of minimal requirements for training. Br J Anaesth. 2013;110(3):347-356. https://doi.org/10.1093/bja/aes499.
176. Ernst A, Silvestri GA, Johnstone D, American College of Chest Physicians. Interventional pulmonary procedures: guidelines from the American College of Chest Physicians. Chest. 2003;123(5):1693-1717. https://doi.org/10.1378/chest.123.5.1693.
177. Thomas SM, Burch W, Kuehnle SE, et al. Simulation training for pediatric residents on central venous catheter placement: a pilot study. Pediatr Crit Care Med J Soc Crit Care Med.. 2013;14(9):e416-e423. https://doi.org/10.1097/PCC.0b013e31829f5eda.
178. Smith KK, Gilcreast D, Pierce K. Evaluation of staff’s retention of ACLS and BLS skills. Resuscitation. 2008;78(1):59-65. https://doi.org/10.1016/j.resuscitation.2008.02.007.
179. Ericsson KA. Deliberate practice and the acquisition and maintenance of expert performance in medicine and related domains. Acad Med. 2004;79(10 Suppl):S70-S81. https://doi.org/10.1097/00001888-200410001-00022.
180. Gerard JM, Thomas SM, Germino KW, et al. The effect of simulation training on PALS skills among family medicine residents. Fam Med. 2011;43(6):392-399.
181. Brydges R, Nair P, Ma I, Shanks D, Hatala R. Directed self-regulated learning versus instructor-regulated learning in simulation training. Med Educ. 2012;46(7):648-656. https://doi.org/10.1111/j.1365-2923.2012.04268.x.
182. Wayne DB, Butter J, Siddall VJ, et al. Simulation-based training of internal medicine residents in advanced cardiac life support protocols: a randomized trial. Teach Learn Med. 2005;17(3):210-216. https://doi.org/10.1207/s15328015tlm1703_3.
183. Arthur Jr. W, Bennett Jr. W, Stanush PL, McNelly TL. Factors that influence skill decay and retention: A quantitative review and analysis. Hum Perform. 1998;11(1):57-101. https://doi.org/10.1207/s15327043hup1101_3.
184. Rusche JD, Besuner P, Partusch SK, Berning PA. Competency program development across a merged healthcare network. J Nurs Staff Dev. 2001;17(5):234-240; quiz 241-232. https://doi.org/10.1097/00124645-200109000-00004.
185. O’Hearne Rebholz M. A review of methods to assess competency. J Nurs Staff Dev. 2006;22(5):241-245. https://doi.org/10.1097/00124645-200609000-00007.
186. Reznick RK. Teaching and testing technical skills. Am J Surg. 1993;165(3):358-361. https://doi.org/10.1016/s0002-9610(05)80843-8.
187. Reznick RK, MacRae H. Teaching surgical skills--changes in the wind. N Engl J Med. 2006;355(25):2664-2669. https://doi.org/10.1056/NEJMra054785.
188. Murin S, Stollenwerk NS. Simulation in procedural training: at the tipping point. Chest. 2010;137(5):1009-1011. https://doi.org/10.1378/chest.10-0199.
189. American College of Emergency Physicians. Emergency ultrasound guidelines. Ann Emerg Med. 2009;53(4):550-570. https://doi.org/10.1016/j.annemergmed.2008.12.013.
190. Guilbert MC, Elkouri S, Bracco D, et al. Arterial trauma during central venous catheter insertion: case series, review and proposed algorithm. J Vasc Surg. 2008;48(4):918-925; discussion 925. https://doi.org/10.1016/j.jvs2008.04.046.
191. Dong Y, Suri HS, Cook DA, et al. Simulation-based objective assessment discerns clinical proficiency in central line placement: a construct validation. Chest. 2010;137(5):1050-1056. https://doi.org/10.1378/chest.09-1451.
192. Adhikari S, Theodoro D, Raio C, et al. Central venous catheterization: are we using ultrasound guidance? J Ultrasound Med. 2015;34(11):2065-2070. https://doi.org/10.7863/ultra.15.01027.
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© 2019 Society of Hospital Medicine
Point-of-Care Ultrasound for Hospitalists: A Position Statement of the Society of Hospital Medicine
Many hospitalists incorporate point-of-care ultrasound (POCUS) into their daily practice because it adds value to their bedside evaluation of patients. However, standards for training and assessing hospitalists in POCUS have not yet been established. Other acute care specialties, including emergency medicine and critical care medicine, have already incorporated POCUS into their graduate medical education training programs, but most internal medicine residency programs are only beginning to provide POCUS training.1
Several features distinguish POCUS from comprehensive ultrasound examinations. First, POCUS is designed to answer focused questions, whereas comprehensive ultrasound examinations evaluate all organs in an anatomical region; for example, an abdominal POCUS exam may evaluate only for presence or absence of intraperitoneal free fluid, whereas a comprehensive examination of the right upper quadrant will evaluate the liver, gallbladder, and biliary ducts. Second, POCUS examinations are generally performed by the same clinician who generates the relevant clinical question to answer with POCUS and ultimately integrates the findings into the patient’s care.2 By contrast, comprehensive ultrasound examinations involve multiple providers and steps: a clinician generates a relevant clinical question and requests an ultrasound examination that is acquired by a sonographer, interpreted by a radiologist, and reported back to the requesting clinician. Third, POCUS is often used to evaluate multiple body systems. For example, to evaluate a patient with undifferentiated hypotension, a multisystem POCUS examination of the heart, inferior vena cava, lungs, abdomen, and lower extremity veins is typically performed. Finally, POCUS examinations can be performed serially to investigate changes in clinical status or evaluate response to therapy, such as monitoring the heart, lungs, and inferior vena cava during fluid resuscitation.
The purpose of this position statement is to inform a broad audience about how hospitalists are using diagnostic and procedural applications of POCUS. This position statement does not mandate that hospitalists use POCUS. Rather, it is intended to provide guidance on the safe and effective use of POCUS by the hospitalists who use it and the administrators who oversee its use. We discuss POCUS (1) applications, (2) training, (3) assessments, and (4) program management. This position statement was reviewed and approved by the Society of Hospital Medicine (SHM) Executive Committee in March 2018.
APPLICATIONS
As outlined in our earlier position statements,3,4 ultrasound guidance lowers complication rates and increases success rates of invasive bedside procedures. Diagnostic POCUS can guide clinical decision making prior to bedside procedures. For instance, hospitalists may use POCUS to assess the size and character of a pleural effusion to help determine the most appropriate management strategy: observation, medical treatment, thoracentesis, chest tube placement, or surgical therapy. Furthermore, diagnostic POCUS can be used to rapidly assess for immediate postprocedural complications, such as pneumothorax, or if the patient develops new symptoms.
TRAINING
Basic Knowledge
Basic knowledge includes fundamentals of ultrasound physics; safety;4 anatomy; physiology; and device operation, including maintenance and cleaning. Basic knowledge can be taught by multiple methods, including live or recorded lectures, online modules, or directed readings.
Image Acquisition
Training should occur across multiple types of patients (eg, obese, cachectic, postsurgical) and clinical settings (eg, intensive care unit, general medicine wards, emergency department) when available. Training is largely hands-on because the relevant skills involve integration of 3D anatomy with spatial manipulation, hand-eye coordination, and fine motor movements. Virtual reality ultrasound simulators may accelerate mastery, particularly for cardiac image acquisition, and expose learners to standardized sets of pathologic findings. Real-time bedside feedback on image acquisition is ideal because understanding how ultrasound probe manipulation affects the images acquired is essential to learning.
Image Interpretation
Training in image interpretation relies on visual pattern recognition of normal and abnormal findings. Therefore, the normal to abnormal spectrum should be broad, and learners should maintain a log of what abnormalities have been identified. Giving real-time feedback at the bedside is ideal because of the connection between image acquisition and interpretation. Image interpretation can be taught through didactic sessions, image review sessions, or review of teaching files with annotated images.
Clinical Integration
Learners must interpret and integrate image findings with other clinical data considering the image quality, patient characteristics, and changing physiology. Clinical integration should be taught by instructors that share similar clinical knowledge as learners. Although sonographers are well suited to teach image acquisition, they should not be the sole instructors to teach hospitalists how to integrate ultrasound findings in clinical decision making. Likewise, emphasis should be placed on the appropriate use of POCUS within a provider’s skill set. Learners must appreciate the clinical significance of POCUS findings, including recognition of incidental findings that may require further workup. Supplemental training in clinical integration can occur through didactics that include complex patient scenarios.
Pathways
Clinical competency can be achieved with training adherent to five criteria. First, the training environment should be similar to where the trainee will practice. Second, training and feedback should occur in real time. Third, specific applications should be taught rather than broad training in “hospitalist POCUS.” Each application requires unique skills and knowledge, including image acquisition pitfalls and artifacts. Fourth, clinical competence must be achieved and demonstrated; it is not necessarily gained through experience. Fifth, once competency is achieved, continued education and feedback are necessary to ensure it is maintained.
Residency-based POCUS training pathways can best fulfill these criteria. They may eventually become commonplace, but until then alternative pathways must exist for hospitalist providers who are already in practice. There are three important attributes of such pathways. First, administrators’ expectations about learners’ clinical productivity must be realistically, but only temporarily, relaxed; otherwise, competing demands on time will likely overwhelm learners and subvert training. Second, training should begin through a local or national hands-on training program. The SHM POCUS certificate program consolidates training for common diagnostic POCUS applications for hospitalists.6 Other medical societies offer training for their respective clinical specialties.7 Third, once basic POCUS training has begun, longitudinal training should continue ideally with a local hospitalist POCUS expert.
In some settings, a subgroup of hospitalists may not desire, or be able to achieve, competency in the manual skills of POCUS image acquisition. Nevertheless, hospitalists may still find value in understanding POCUS nomenclature, image pattern recognition, and the evidence and pitfalls behind clinical integration of specific POCUS findings. This subset of POCUS skills allows hospitalists to communicate effectively with and understand the clinical decisions made by their colleagues who are competent in POCUS use.
The minimal skills a hospitalist should possess to serve as a POCUS trainer include proficiency of basic knowledge, image acquisition, image interpretation, and clinical integration of the POCUS applications being taught; effectiveness as a hands-on instructor to teach image acquisition skills; and an in-depth understanding of common POCUS pitfalls and limitations.
ASSESSMENTS
Assessment methods for POCUS can include the following: knowledge-based questions, image acquisition using task-specific checklists on human or simulation models, image interpretation using a series of videos or still images with normal and abnormal findings, clinical integration using “next best step” in a multiple choice format with POCUS images, and simulation-based clinical scenarios. Assessment methods should be aligned with local availability of resources and trainers.
Basic Knowledge
Basic knowledge can be assessed via multiple choice questions assessing knowledge of ultrasound physics, image optimization, relevant anatomy, and limitations of POCUS imaging. Basic knowledge lies primarily in the cognitive domain and does not assess manual skills.
Image Acquisition
Image acquisition can be assessed by observation and rating of image quality. Where resources allow, assessment of image acquisition is likely best done through a combination of developing an image portfolio with a minimum number of high quality images, plus direct observation of image acquisition by an expert. Various programs have utilized minimum numbers of images acquired to help define competence with image acquisition skills.6–8 Although minimums may be a necessary step to gain competence, using them as a sole means to determine competence does not account for variable learning curves.9 As with other manual skills in hospital medicine, such as ultrasound-guided bedside procedures, minimum numbers are best used as a starting point for assessments.3,10 In this regard, portfolio development with meticulous attention to the gain, depth, and proper tomographic plane of images can monitor a hospitalist’s progress toward competence by providing objective assessments and feedback. Simulation may also be used as it allows assessment of image acquisition skills and an opportunity to provide real-time feedback, similar to direct observation but without actual patients.
Image Interpretation
Image interpretation is best assessed by an expert observing the learner at bedside; however, when bedside assessment is not possible, image interpretation skills may be assessed using multiple choice or free text interpretation of archived ultrasound images with normal and abnormal findings. This is often incorporated into the portfolio development portion of a training program, as learners can submit their image interpretation along with the video clip. Both normal and abnormal images can be used to assess anatomic recognition and interpretation. Emphasis should be placed on determining when an image is suboptimal for diagnosis (eg, incomplete exam or poor-quality images). Quality assurance programs should incorporate structured feedback sessions.
Clinical Integration
Assessment of clinical integration can be completed through case scenarios that assess knowledge, interpretation of images, and integration of findings into clinical decision making, which is often delivered via a computer-based assessment. Assessments should combine specific POCUS applications to evaluate common clinical problems in hospital medicine, such as undifferentiated hypotension and dyspnea. High-fidelity simulators can be used to blend clinical case scenarios with image acquisition, image interpretation, and clinical integration. When feasible, comprehensive feedback on how providers acquire, interpret, and apply ultrasound at the bedside is likely the best mechanism to assess clinical integration. This process can be done with a hospitalist’s own patients.
General Assessment
A general assessment that includes a summative knowledge and hands-on skills assessment using task-specific checklists can be performed upon completion of training. A high-fidelity simulator with dynamic or virtual anatomy can provide reproducible standardized assessments with variation in the type and difficulty of cases. When available, we encourage the use of dynamic assessments on actual patients that have both normal and abnormal ultrasound findings because simulated patient scenarios have limitations, even with the use of high-fidelity simulators. Programs are recommended to use formative and summative assessments for evaluation. Quantitative scoring systems using checklists are likely the best framework.11,12
CERTIFICATES AND CERTIFICATION
A certificate of completion is proof of a provider’s participation in an educational activity; it does not equate with competency, though it may be a step toward it. Most POCUS training workshops and short courses provide certificates of completion. Certification of competency is an attestation of a hospitalist’s basic competence within a defined scope of practice (Table 2).13 However, without longitudinal supervision and feedback, skills can decay; therefore, we recommend a longitudinal training program that provides mentored feedback and incorporates periodic competency assessments. At present, no national board certification in POCUS is available to grant external certification of competency for hospitalists.
External Certificate
Certificates of completion can be external through a national organization. An external certificate of completion designed for hospitalists includes the POCUS Certificate of Completion offered by SHM in collaboration with CHEST.6 This certificate program provides regional training options and longitudinal portfolio development. Other external certificates are also available to hospitalists.7,14,15
Most hospitalists are boarded by the American Board of Internal Medicine or the American Board of Family Medicine. These boards do not yet include certification of competency in POCUS. Other specialty boards, such as emergency medicine, include competency in POCUS. For emergency medicine, completion of an accredited residency training program and certification by the national board includes POCUS competency.
Internal Certificate
There are a few examples of successful local institutional programs that have provided internal certificates of competency.12,14 Competency assessments require significant resources including investment by both faculty and learners. Ongoing evaluation of competency should be based on quality assurance processes.
Credentialing and Privileging
The American Medical Association (AMA) House of Delegates in 1999 passed a resolution (AMA HR. 802) recommending hospitals follow specialty-specific guidelines for privileging decisions related to POCUS use.17 The resolution included a statement that, “ultrasound imaging is within the scope of practice of appropriately trained physicians.”
Some institutions have begun to rely on a combination of internal and external certificate programs to grant privileges to hospitalists.10 Although specific privileges for POCUS may not be required in some hospitals, some institutions may require certification of training and assessments prior to granting permission to use POCUS.
Hospitalist programs are encouraged to evaluate ongoing POCUS use by their providers after granting initial permission. If privileging is instituted by a hospital, hospitalists must play a significant role in determining the requirements for privileging and ongoing maintenance of skills.
Maintenance of Skills
All medical skills can decay with disuse, including those associated with POCUS.12,18 Thus, POCUS users should continue using POCUS regularly in clinical practice and participate in POCUS continuing medical education activities, ideally with ongoing assessments. Maintenance of skills may be confirmed through routine participation in a quality assurance program.
PROGRAM MANAGEMENT
Use of POCUS in hospital medicine has unique considerations, and hospitalists should be integrally involved in decision making surrounding institutional POCUS program management. Appointing a dedicated POCUS director can help a program succeed.8
Equipment and Image Archiving
Several factors are important to consider when selecting an ultrasound machine: portability, screen size, and ease of use; integration with the electronic medical record and options for image archiving; manufacturer’s service plan, including technical and clinical support; and compliance with local infection control policies. The ability to easily archive and retrieve images is essential for quality assurance, continuing education, institutional quality improvement, documentation, and reimbursement. In certain scenarios, image archiving may not be possible (such as with personal handheld devices or in emergency situations) or necessary (such as with frequent serial examinations during fluid resuscitation). An image archive is ideally linked to reports, orders, and billing software.10,19 If such linkages are not feasible, parallel external storage that complies with regulatory standards (ie, HIPAA compliance) may be suitable.20
Documentation and Billing
Components of documentation include the indication and type of ultrasound examination performed, date and time of the examination, patient identifying information, name of provider(s) acquiring and interpreting the images, specific scanning protocols used, patient position, probe used, and findings. Documentation can occur through a standalone note or as part of another note, such as a progress note. Whenever possible, documentation should be timely to facilitate communication with other providers.
Billing is supported through the AMA Current Procedural Terminology codes for “focused” or “limited” ultrasound examinations (Appendix 9). The following three criteria must be satisfied for billing. First, images must be permanently stored. Specific requirements vary by insurance policy, though current practice suggests a minimum of one image demonstrating relevant anatomy and pathology for the ultrasound examination coded. For ultrasound-guided procedures that require needle insertion, images should be captured at the point of interest, and a procedure note should reflect that the needle was guided and visualized under ultrasound.21 Second, proper documentation must be entered in the medical record. Third, local institutional privileges for POCUS must be considered. Although privileges are not required to bill, some hospitals or payers may require them.
Quality Assurance
Published guidelines on quality assurance in POCUS are available from different specialty organizations, including emergency medicine, pediatric emergency medicine, critical care, anesthesiology, obstetrics, and cardiology.8,22–28 Quality assurance is aimed at ensuring that physicians maintain basic competency in using POCUS to influence bedside decisions.
Quality assurance should be carried out by an individual or committee with expertise in POCUS. Multidisciplinary QA programs in which hospital medicine providers are working collaboratively with other POCUS providers have been demonstrated to be highly effective.10 Oversight includes ensuring that providers using POCUS are appropriately trained,10,22,28 using the equipment correctly,8,26,28 and documenting properly. Some programs have implemented mechanisms to review and provide feedback on image acquisition, interpretation, and clinical integration.8,10 Other programs have compared POCUS findings with referral studies, such as comprehensive ultrasound examinations.
CONCLUSIONS
Practicing hospitalists must continue to collaborate with their institutions to build POCUS capabilities. In particular, they must work with their local privileging body to determine what credentials are required. The distinction between certificates of completion and certificates of competency, including whether those certificates are internal or external, is important in the credentialing process.
External certificates of competency are currently unavailable for most practicing hospitalists because ABIM certification does not include POCUS-related competencies. As internal medicine residency training programs begin to adopt POCUS training and certification into their educational curricula, we foresee a need to update the ABIM Policies and Procedures for Certification. Until then, we recommend that certificates of competency be defined and granted internally by local hospitalist groups.
Given the many advantages of POCUS over traditional tools, we anticipate its increasing implementation among hospitalists in the future. As with all medical technology, its role in clinical care should be continuously reexamined and redefined through health services research. Such information will be useful in developing practice guidelines, educational curricula, and training standards.
Acknowledgments
The authors would like to thank all members that participated in the discussion and finalization of this position statement during the Point-of-care Ultrasound Faculty Retreat at the 2018 Society of Hospital Medicine Annual Conference: Saaid Abdel-Ghani, Brandon Boesch, Joel Cho, Ria Dancel, Renee Dversdal, Ricardo Franco-Sadud, Benjamin Galen, Trevor P. Jensen, Mohit Jindal, Gordon Johnson, Linda M. Kurian, Gigi Liu, Charles M. LoPresti, Brian P. Lucas, Venkat Kalidindi, Benji Matthews, Anna Maw, Gregory Mints, Kreegan Reierson, Gerard Salame, Richard Schildhouse, Daniel Schnobrich, Nilam Soni, Kirk Spencer, Hiromizu Takahashi, David M. Tierney, Tanping Wong, and Toru Yamada.
1. Schnobrich DJ, Mathews BK, Trappey BE, Muthyala BK, Olson APJ. Entrusting internal medicine residents to use point of care ultrasound: Towards improved assessment and supervision. Med Teach. 2018:1-6. doi:10.1080/0142159X.2018.1457210.
2. Soni NJ, Lucas BP. Diagnostic point-of-care ultrasound for hospitalists. J Hosp Med. 2015;10(2):120-124. doi:10.1002/jhm.2285.
3. Lucas BP, Tierney DM, Jensen TP, et al. Credentialing of hospitalists in ultrasound-guided bedside procedures: a position statement of the society of hospital medicine. J Hosp Med. 2018;13(2):117-125. doi:10.12788/jhm.2917.
4. Dancel R, Schnobrich D, Puri N, et al. Recommendations on the use of ultrasound guidance for adult thoracentesis: a position statement of the society of hospital medicine. J Hosp Med. 2018;13(2):126-135. doi:10.12788/jhm.2940.
5. National Council on Radiation Protection and Measurements, The Council. Implementation of the Principle of as Low as Reasonably Achievable (ALARA) for Medical and Dental Personnel.; 1990.
6. Society of Hospital Medicine. Point of Care Ultrasound course: https://www.hospitalmedicine.org/clinical-topics/ultrasonography-cert/. Accessed February 6, 2018.
7. Critical Care Ultrasonography Certificate of Completion Program. CHEST. American College of Chest Physicians. http://www.chestnet.org/Education/Advanced-Clinical-Training/Certificate-of-Completion-Program/Critical-Care-Ultrasonography. Accessed February 6, 2018.
8. American College of Emergency Physicians Policy Statement: Emergency Ultrasound Guidelines. 2016. https://www.acep.org/Clinical---Practice-Management/ACEP-Ultrasound-Guidelines/. Accessed February 6, 2018.
9. Blehar DJ, Barton B, Gaspari RJ. Learning curves in emergency ultrasound education. Acad Emerg Med. 2015;22(5):574-582. doi:10.1111/acem.12653.
10. Mathews BK, Zwank M. Hospital medicine point of care ultrasound credentialing: an example protocol. J Hosp Med. 2017;12(9):767-772. doi:10.12788/jhm.2809.
11. Barsuk JH, McGaghie WC, Cohen ER, Balachandran JS, Wayne DB. Use of simulation-based mastery learning to improve the quality of central venous catheter placement in a medical intensive care unit. J Hosp Med. 2009;4(7):397-403. doi:10.1002/jhm.468.
12. Mathews BK, Reierson K, Vuong K, et al. The design and evaluation of the Comprehensive Hospitalist Assessment and Mentorship with Portfolios (CHAMP) ultrasound program. J Hosp Med. 2018;13(8):544-550. doi:10.12788/jhm.2938.
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16. Tierney DM. Internal Medicine Bedside Ultrasound Program (IMBUS). Abbott Northwestern. http://imbus.anwresidency.com/index.html. Accessed February 6, 2018.
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18. Kelm D, Ratelle J, Azeem N, et al. Longitudinal ultrasound curriculum improves long-term retention among internal medicine residents. J Grad Med Educ. 2015;7(3):454-457. doi:10.4300/JGME-14-00284.1.
19. Flannigan MJ, Adhikari S. Point-of-care ultrasound work flow innovation: impact on documentation and billing. J Ultrasound Med. 2017;36(12):2467-2474. doi:10.1002/jum.14284.
20. Emergency Ultrasound: Workflow White Paper. https://www.acep.org/uploadedFiles/ACEP/memberCenter/SectionsofMembership/ultra/Workflow%20White%20Paper.pdf. Published 2013. Accessed February 18, 2018.
21. Ultrasound Coding and Reimbursement Document 2009. Emergency Ultrasound Section. American College of Emergency Physicians. http://emergencyultrasoundteaching.com/assets/2009_coding_update.pdf. Published 2009. Accessed February 18, 2018.
22. Mayo PH, Beaulieu Y, Doelken P, et al. American College of Chest Physicians/La Societe de Reanimation de Langue Francaise statement on competence in critical care ultrasonography. Chest. 2009;135(4):1050-1060. doi:10.1378/chest.08-2305.
23. Frankel HL, Kirkpatrick AW, Elbarbary M, et al. Guidelines for the appropriate use of bedside general and cardiac ultrasonography in the evaluation of critically ill patients-part I: general ultrasonography. Crit Care Med. 2015;43(11):2479-2502. doi:10.1097/ccm.0000000000001216.
24. Levitov A, Frankel HL, Blaivas M, et al. Guidelines for the appropriate use of bedside general and cardiac ultrasonography in the evaluation of critically ill patients-part ii: cardiac ultrasonography. Crit Care Med. 2016;44(6):1206-1227. doi:10.1097/ccm.0000000000001847.
25. ACR–ACOG–AIUM–SRU Practice Parameter for the Performance of Obstetrical Ultrasound. https://www.acr.org/-/media/ACR/Files/Practice-Parameters/us-ob.pdf. Published 2013. Accessed February 18, 2018.
26. AIUM practice guideline for documentation of an ultrasound examination. J Ultrasound Med. 2014;33(6):1098-1102. doi:10.7863/ultra.33.6.1098.
27. Marin JR, Lewiss RE. Point-of-care ultrasonography by pediatric emergency medicine physicians. Pediatrics. 2015;135(4):e1113-e1122. doi:10.1542/peds.2015-0343.
28. Spencer KT, Kimura BJ, Korcarz CE, Pellikka PA, Rahko PS, Siegel RJ. Focused cardiac ultrasound: recommendations from the American Society of Echocardiography. J Am Soc Echocardiogr. 2013;26(6):567-581. doi:10.1016/j.echo.2013.04.001.
Many hospitalists incorporate point-of-care ultrasound (POCUS) into their daily practice because it adds value to their bedside evaluation of patients. However, standards for training and assessing hospitalists in POCUS have not yet been established. Other acute care specialties, including emergency medicine and critical care medicine, have already incorporated POCUS into their graduate medical education training programs, but most internal medicine residency programs are only beginning to provide POCUS training.1
Several features distinguish POCUS from comprehensive ultrasound examinations. First, POCUS is designed to answer focused questions, whereas comprehensive ultrasound examinations evaluate all organs in an anatomical region; for example, an abdominal POCUS exam may evaluate only for presence or absence of intraperitoneal free fluid, whereas a comprehensive examination of the right upper quadrant will evaluate the liver, gallbladder, and biliary ducts. Second, POCUS examinations are generally performed by the same clinician who generates the relevant clinical question to answer with POCUS and ultimately integrates the findings into the patient’s care.2 By contrast, comprehensive ultrasound examinations involve multiple providers and steps: a clinician generates a relevant clinical question and requests an ultrasound examination that is acquired by a sonographer, interpreted by a radiologist, and reported back to the requesting clinician. Third, POCUS is often used to evaluate multiple body systems. For example, to evaluate a patient with undifferentiated hypotension, a multisystem POCUS examination of the heart, inferior vena cava, lungs, abdomen, and lower extremity veins is typically performed. Finally, POCUS examinations can be performed serially to investigate changes in clinical status or evaluate response to therapy, such as monitoring the heart, lungs, and inferior vena cava during fluid resuscitation.
The purpose of this position statement is to inform a broad audience about how hospitalists are using diagnostic and procedural applications of POCUS. This position statement does not mandate that hospitalists use POCUS. Rather, it is intended to provide guidance on the safe and effective use of POCUS by the hospitalists who use it and the administrators who oversee its use. We discuss POCUS (1) applications, (2) training, (3) assessments, and (4) program management. This position statement was reviewed and approved by the Society of Hospital Medicine (SHM) Executive Committee in March 2018.
APPLICATIONS
As outlined in our earlier position statements,3,4 ultrasound guidance lowers complication rates and increases success rates of invasive bedside procedures. Diagnostic POCUS can guide clinical decision making prior to bedside procedures. For instance, hospitalists may use POCUS to assess the size and character of a pleural effusion to help determine the most appropriate management strategy: observation, medical treatment, thoracentesis, chest tube placement, or surgical therapy. Furthermore, diagnostic POCUS can be used to rapidly assess for immediate postprocedural complications, such as pneumothorax, or if the patient develops new symptoms.
TRAINING
Basic Knowledge
Basic knowledge includes fundamentals of ultrasound physics; safety;4 anatomy; physiology; and device operation, including maintenance and cleaning. Basic knowledge can be taught by multiple methods, including live or recorded lectures, online modules, or directed readings.
Image Acquisition
Training should occur across multiple types of patients (eg, obese, cachectic, postsurgical) and clinical settings (eg, intensive care unit, general medicine wards, emergency department) when available. Training is largely hands-on because the relevant skills involve integration of 3D anatomy with spatial manipulation, hand-eye coordination, and fine motor movements. Virtual reality ultrasound simulators may accelerate mastery, particularly for cardiac image acquisition, and expose learners to standardized sets of pathologic findings. Real-time bedside feedback on image acquisition is ideal because understanding how ultrasound probe manipulation affects the images acquired is essential to learning.
Image Interpretation
Training in image interpretation relies on visual pattern recognition of normal and abnormal findings. Therefore, the normal to abnormal spectrum should be broad, and learners should maintain a log of what abnormalities have been identified. Giving real-time feedback at the bedside is ideal because of the connection between image acquisition and interpretation. Image interpretation can be taught through didactic sessions, image review sessions, or review of teaching files with annotated images.
Clinical Integration
Learners must interpret and integrate image findings with other clinical data considering the image quality, patient characteristics, and changing physiology. Clinical integration should be taught by instructors that share similar clinical knowledge as learners. Although sonographers are well suited to teach image acquisition, they should not be the sole instructors to teach hospitalists how to integrate ultrasound findings in clinical decision making. Likewise, emphasis should be placed on the appropriate use of POCUS within a provider’s skill set. Learners must appreciate the clinical significance of POCUS findings, including recognition of incidental findings that may require further workup. Supplemental training in clinical integration can occur through didactics that include complex patient scenarios.
Pathways
Clinical competency can be achieved with training adherent to five criteria. First, the training environment should be similar to where the trainee will practice. Second, training and feedback should occur in real time. Third, specific applications should be taught rather than broad training in “hospitalist POCUS.” Each application requires unique skills and knowledge, including image acquisition pitfalls and artifacts. Fourth, clinical competence must be achieved and demonstrated; it is not necessarily gained through experience. Fifth, once competency is achieved, continued education and feedback are necessary to ensure it is maintained.
Residency-based POCUS training pathways can best fulfill these criteria. They may eventually become commonplace, but until then alternative pathways must exist for hospitalist providers who are already in practice. There are three important attributes of such pathways. First, administrators’ expectations about learners’ clinical productivity must be realistically, but only temporarily, relaxed; otherwise, competing demands on time will likely overwhelm learners and subvert training. Second, training should begin through a local or national hands-on training program. The SHM POCUS certificate program consolidates training for common diagnostic POCUS applications for hospitalists.6 Other medical societies offer training for their respective clinical specialties.7 Third, once basic POCUS training has begun, longitudinal training should continue ideally with a local hospitalist POCUS expert.
In some settings, a subgroup of hospitalists may not desire, or be able to achieve, competency in the manual skills of POCUS image acquisition. Nevertheless, hospitalists may still find value in understanding POCUS nomenclature, image pattern recognition, and the evidence and pitfalls behind clinical integration of specific POCUS findings. This subset of POCUS skills allows hospitalists to communicate effectively with and understand the clinical decisions made by their colleagues who are competent in POCUS use.
The minimal skills a hospitalist should possess to serve as a POCUS trainer include proficiency of basic knowledge, image acquisition, image interpretation, and clinical integration of the POCUS applications being taught; effectiveness as a hands-on instructor to teach image acquisition skills; and an in-depth understanding of common POCUS pitfalls and limitations.
ASSESSMENTS
Assessment methods for POCUS can include the following: knowledge-based questions, image acquisition using task-specific checklists on human or simulation models, image interpretation using a series of videos or still images with normal and abnormal findings, clinical integration using “next best step” in a multiple choice format with POCUS images, and simulation-based clinical scenarios. Assessment methods should be aligned with local availability of resources and trainers.
Basic Knowledge
Basic knowledge can be assessed via multiple choice questions assessing knowledge of ultrasound physics, image optimization, relevant anatomy, and limitations of POCUS imaging. Basic knowledge lies primarily in the cognitive domain and does not assess manual skills.
Image Acquisition
Image acquisition can be assessed by observation and rating of image quality. Where resources allow, assessment of image acquisition is likely best done through a combination of developing an image portfolio with a minimum number of high quality images, plus direct observation of image acquisition by an expert. Various programs have utilized minimum numbers of images acquired to help define competence with image acquisition skills.6–8 Although minimums may be a necessary step to gain competence, using them as a sole means to determine competence does not account for variable learning curves.9 As with other manual skills in hospital medicine, such as ultrasound-guided bedside procedures, minimum numbers are best used as a starting point for assessments.3,10 In this regard, portfolio development with meticulous attention to the gain, depth, and proper tomographic plane of images can monitor a hospitalist’s progress toward competence by providing objective assessments and feedback. Simulation may also be used as it allows assessment of image acquisition skills and an opportunity to provide real-time feedback, similar to direct observation but without actual patients.
Image Interpretation
Image interpretation is best assessed by an expert observing the learner at bedside; however, when bedside assessment is not possible, image interpretation skills may be assessed using multiple choice or free text interpretation of archived ultrasound images with normal and abnormal findings. This is often incorporated into the portfolio development portion of a training program, as learners can submit their image interpretation along with the video clip. Both normal and abnormal images can be used to assess anatomic recognition and interpretation. Emphasis should be placed on determining when an image is suboptimal for diagnosis (eg, incomplete exam or poor-quality images). Quality assurance programs should incorporate structured feedback sessions.
Clinical Integration
Assessment of clinical integration can be completed through case scenarios that assess knowledge, interpretation of images, and integration of findings into clinical decision making, which is often delivered via a computer-based assessment. Assessments should combine specific POCUS applications to evaluate common clinical problems in hospital medicine, such as undifferentiated hypotension and dyspnea. High-fidelity simulators can be used to blend clinical case scenarios with image acquisition, image interpretation, and clinical integration. When feasible, comprehensive feedback on how providers acquire, interpret, and apply ultrasound at the bedside is likely the best mechanism to assess clinical integration. This process can be done with a hospitalist’s own patients.
General Assessment
A general assessment that includes a summative knowledge and hands-on skills assessment using task-specific checklists can be performed upon completion of training. A high-fidelity simulator with dynamic or virtual anatomy can provide reproducible standardized assessments with variation in the type and difficulty of cases. When available, we encourage the use of dynamic assessments on actual patients that have both normal and abnormal ultrasound findings because simulated patient scenarios have limitations, even with the use of high-fidelity simulators. Programs are recommended to use formative and summative assessments for evaluation. Quantitative scoring systems using checklists are likely the best framework.11,12
CERTIFICATES AND CERTIFICATION
A certificate of completion is proof of a provider’s participation in an educational activity; it does not equate with competency, though it may be a step toward it. Most POCUS training workshops and short courses provide certificates of completion. Certification of competency is an attestation of a hospitalist’s basic competence within a defined scope of practice (Table 2).13 However, without longitudinal supervision and feedback, skills can decay; therefore, we recommend a longitudinal training program that provides mentored feedback and incorporates periodic competency assessments. At present, no national board certification in POCUS is available to grant external certification of competency for hospitalists.
External Certificate
Certificates of completion can be external through a national organization. An external certificate of completion designed for hospitalists includes the POCUS Certificate of Completion offered by SHM in collaboration with CHEST.6 This certificate program provides regional training options and longitudinal portfolio development. Other external certificates are also available to hospitalists.7,14,15
Most hospitalists are boarded by the American Board of Internal Medicine or the American Board of Family Medicine. These boards do not yet include certification of competency in POCUS. Other specialty boards, such as emergency medicine, include competency in POCUS. For emergency medicine, completion of an accredited residency training program and certification by the national board includes POCUS competency.
Internal Certificate
There are a few examples of successful local institutional programs that have provided internal certificates of competency.12,14 Competency assessments require significant resources including investment by both faculty and learners. Ongoing evaluation of competency should be based on quality assurance processes.
Credentialing and Privileging
The American Medical Association (AMA) House of Delegates in 1999 passed a resolution (AMA HR. 802) recommending hospitals follow specialty-specific guidelines for privileging decisions related to POCUS use.17 The resolution included a statement that, “ultrasound imaging is within the scope of practice of appropriately trained physicians.”
Some institutions have begun to rely on a combination of internal and external certificate programs to grant privileges to hospitalists.10 Although specific privileges for POCUS may not be required in some hospitals, some institutions may require certification of training and assessments prior to granting permission to use POCUS.
Hospitalist programs are encouraged to evaluate ongoing POCUS use by their providers after granting initial permission. If privileging is instituted by a hospital, hospitalists must play a significant role in determining the requirements for privileging and ongoing maintenance of skills.
Maintenance of Skills
All medical skills can decay with disuse, including those associated with POCUS.12,18 Thus, POCUS users should continue using POCUS regularly in clinical practice and participate in POCUS continuing medical education activities, ideally with ongoing assessments. Maintenance of skills may be confirmed through routine participation in a quality assurance program.
PROGRAM MANAGEMENT
Use of POCUS in hospital medicine has unique considerations, and hospitalists should be integrally involved in decision making surrounding institutional POCUS program management. Appointing a dedicated POCUS director can help a program succeed.8
Equipment and Image Archiving
Several factors are important to consider when selecting an ultrasound machine: portability, screen size, and ease of use; integration with the electronic medical record and options for image archiving; manufacturer’s service plan, including technical and clinical support; and compliance with local infection control policies. The ability to easily archive and retrieve images is essential for quality assurance, continuing education, institutional quality improvement, documentation, and reimbursement. In certain scenarios, image archiving may not be possible (such as with personal handheld devices or in emergency situations) or necessary (such as with frequent serial examinations during fluid resuscitation). An image archive is ideally linked to reports, orders, and billing software.10,19 If such linkages are not feasible, parallel external storage that complies with regulatory standards (ie, HIPAA compliance) may be suitable.20
Documentation and Billing
Components of documentation include the indication and type of ultrasound examination performed, date and time of the examination, patient identifying information, name of provider(s) acquiring and interpreting the images, specific scanning protocols used, patient position, probe used, and findings. Documentation can occur through a standalone note or as part of another note, such as a progress note. Whenever possible, documentation should be timely to facilitate communication with other providers.
Billing is supported through the AMA Current Procedural Terminology codes for “focused” or “limited” ultrasound examinations (Appendix 9). The following three criteria must be satisfied for billing. First, images must be permanently stored. Specific requirements vary by insurance policy, though current practice suggests a minimum of one image demonstrating relevant anatomy and pathology for the ultrasound examination coded. For ultrasound-guided procedures that require needle insertion, images should be captured at the point of interest, and a procedure note should reflect that the needle was guided and visualized under ultrasound.21 Second, proper documentation must be entered in the medical record. Third, local institutional privileges for POCUS must be considered. Although privileges are not required to bill, some hospitals or payers may require them.
Quality Assurance
Published guidelines on quality assurance in POCUS are available from different specialty organizations, including emergency medicine, pediatric emergency medicine, critical care, anesthesiology, obstetrics, and cardiology.8,22–28 Quality assurance is aimed at ensuring that physicians maintain basic competency in using POCUS to influence bedside decisions.
Quality assurance should be carried out by an individual or committee with expertise in POCUS. Multidisciplinary QA programs in which hospital medicine providers are working collaboratively with other POCUS providers have been demonstrated to be highly effective.10 Oversight includes ensuring that providers using POCUS are appropriately trained,10,22,28 using the equipment correctly,8,26,28 and documenting properly. Some programs have implemented mechanisms to review and provide feedback on image acquisition, interpretation, and clinical integration.8,10 Other programs have compared POCUS findings with referral studies, such as comprehensive ultrasound examinations.
CONCLUSIONS
Practicing hospitalists must continue to collaborate with their institutions to build POCUS capabilities. In particular, they must work with their local privileging body to determine what credentials are required. The distinction between certificates of completion and certificates of competency, including whether those certificates are internal or external, is important in the credentialing process.
External certificates of competency are currently unavailable for most practicing hospitalists because ABIM certification does not include POCUS-related competencies. As internal medicine residency training programs begin to adopt POCUS training and certification into their educational curricula, we foresee a need to update the ABIM Policies and Procedures for Certification. Until then, we recommend that certificates of competency be defined and granted internally by local hospitalist groups.
Given the many advantages of POCUS over traditional tools, we anticipate its increasing implementation among hospitalists in the future. As with all medical technology, its role in clinical care should be continuously reexamined and redefined through health services research. Such information will be useful in developing practice guidelines, educational curricula, and training standards.
Acknowledgments
The authors would like to thank all members that participated in the discussion and finalization of this position statement during the Point-of-care Ultrasound Faculty Retreat at the 2018 Society of Hospital Medicine Annual Conference: Saaid Abdel-Ghani, Brandon Boesch, Joel Cho, Ria Dancel, Renee Dversdal, Ricardo Franco-Sadud, Benjamin Galen, Trevor P. Jensen, Mohit Jindal, Gordon Johnson, Linda M. Kurian, Gigi Liu, Charles M. LoPresti, Brian P. Lucas, Venkat Kalidindi, Benji Matthews, Anna Maw, Gregory Mints, Kreegan Reierson, Gerard Salame, Richard Schildhouse, Daniel Schnobrich, Nilam Soni, Kirk Spencer, Hiromizu Takahashi, David M. Tierney, Tanping Wong, and Toru Yamada.
Many hospitalists incorporate point-of-care ultrasound (POCUS) into their daily practice because it adds value to their bedside evaluation of patients. However, standards for training and assessing hospitalists in POCUS have not yet been established. Other acute care specialties, including emergency medicine and critical care medicine, have already incorporated POCUS into their graduate medical education training programs, but most internal medicine residency programs are only beginning to provide POCUS training.1
Several features distinguish POCUS from comprehensive ultrasound examinations. First, POCUS is designed to answer focused questions, whereas comprehensive ultrasound examinations evaluate all organs in an anatomical region; for example, an abdominal POCUS exam may evaluate only for presence or absence of intraperitoneal free fluid, whereas a comprehensive examination of the right upper quadrant will evaluate the liver, gallbladder, and biliary ducts. Second, POCUS examinations are generally performed by the same clinician who generates the relevant clinical question to answer with POCUS and ultimately integrates the findings into the patient’s care.2 By contrast, comprehensive ultrasound examinations involve multiple providers and steps: a clinician generates a relevant clinical question and requests an ultrasound examination that is acquired by a sonographer, interpreted by a radiologist, and reported back to the requesting clinician. Third, POCUS is often used to evaluate multiple body systems. For example, to evaluate a patient with undifferentiated hypotension, a multisystem POCUS examination of the heart, inferior vena cava, lungs, abdomen, and lower extremity veins is typically performed. Finally, POCUS examinations can be performed serially to investigate changes in clinical status or evaluate response to therapy, such as monitoring the heart, lungs, and inferior vena cava during fluid resuscitation.
The purpose of this position statement is to inform a broad audience about how hospitalists are using diagnostic and procedural applications of POCUS. This position statement does not mandate that hospitalists use POCUS. Rather, it is intended to provide guidance on the safe and effective use of POCUS by the hospitalists who use it and the administrators who oversee its use. We discuss POCUS (1) applications, (2) training, (3) assessments, and (4) program management. This position statement was reviewed and approved by the Society of Hospital Medicine (SHM) Executive Committee in March 2018.
APPLICATIONS
As outlined in our earlier position statements,3,4 ultrasound guidance lowers complication rates and increases success rates of invasive bedside procedures. Diagnostic POCUS can guide clinical decision making prior to bedside procedures. For instance, hospitalists may use POCUS to assess the size and character of a pleural effusion to help determine the most appropriate management strategy: observation, medical treatment, thoracentesis, chest tube placement, or surgical therapy. Furthermore, diagnostic POCUS can be used to rapidly assess for immediate postprocedural complications, such as pneumothorax, or if the patient develops new symptoms.
TRAINING
Basic Knowledge
Basic knowledge includes fundamentals of ultrasound physics; safety;4 anatomy; physiology; and device operation, including maintenance and cleaning. Basic knowledge can be taught by multiple methods, including live or recorded lectures, online modules, or directed readings.
Image Acquisition
Training should occur across multiple types of patients (eg, obese, cachectic, postsurgical) and clinical settings (eg, intensive care unit, general medicine wards, emergency department) when available. Training is largely hands-on because the relevant skills involve integration of 3D anatomy with spatial manipulation, hand-eye coordination, and fine motor movements. Virtual reality ultrasound simulators may accelerate mastery, particularly for cardiac image acquisition, and expose learners to standardized sets of pathologic findings. Real-time bedside feedback on image acquisition is ideal because understanding how ultrasound probe manipulation affects the images acquired is essential to learning.
Image Interpretation
Training in image interpretation relies on visual pattern recognition of normal and abnormal findings. Therefore, the normal to abnormal spectrum should be broad, and learners should maintain a log of what abnormalities have been identified. Giving real-time feedback at the bedside is ideal because of the connection between image acquisition and interpretation. Image interpretation can be taught through didactic sessions, image review sessions, or review of teaching files with annotated images.
Clinical Integration
Learners must interpret and integrate image findings with other clinical data considering the image quality, patient characteristics, and changing physiology. Clinical integration should be taught by instructors that share similar clinical knowledge as learners. Although sonographers are well suited to teach image acquisition, they should not be the sole instructors to teach hospitalists how to integrate ultrasound findings in clinical decision making. Likewise, emphasis should be placed on the appropriate use of POCUS within a provider’s skill set. Learners must appreciate the clinical significance of POCUS findings, including recognition of incidental findings that may require further workup. Supplemental training in clinical integration can occur through didactics that include complex patient scenarios.
Pathways
Clinical competency can be achieved with training adherent to five criteria. First, the training environment should be similar to where the trainee will practice. Second, training and feedback should occur in real time. Third, specific applications should be taught rather than broad training in “hospitalist POCUS.” Each application requires unique skills and knowledge, including image acquisition pitfalls and artifacts. Fourth, clinical competence must be achieved and demonstrated; it is not necessarily gained through experience. Fifth, once competency is achieved, continued education and feedback are necessary to ensure it is maintained.
Residency-based POCUS training pathways can best fulfill these criteria. They may eventually become commonplace, but until then alternative pathways must exist for hospitalist providers who are already in practice. There are three important attributes of such pathways. First, administrators’ expectations about learners’ clinical productivity must be realistically, but only temporarily, relaxed; otherwise, competing demands on time will likely overwhelm learners and subvert training. Second, training should begin through a local or national hands-on training program. The SHM POCUS certificate program consolidates training for common diagnostic POCUS applications for hospitalists.6 Other medical societies offer training for their respective clinical specialties.7 Third, once basic POCUS training has begun, longitudinal training should continue ideally with a local hospitalist POCUS expert.
In some settings, a subgroup of hospitalists may not desire, or be able to achieve, competency in the manual skills of POCUS image acquisition. Nevertheless, hospitalists may still find value in understanding POCUS nomenclature, image pattern recognition, and the evidence and pitfalls behind clinical integration of specific POCUS findings. This subset of POCUS skills allows hospitalists to communicate effectively with and understand the clinical decisions made by their colleagues who are competent in POCUS use.
The minimal skills a hospitalist should possess to serve as a POCUS trainer include proficiency of basic knowledge, image acquisition, image interpretation, and clinical integration of the POCUS applications being taught; effectiveness as a hands-on instructor to teach image acquisition skills; and an in-depth understanding of common POCUS pitfalls and limitations.
ASSESSMENTS
Assessment methods for POCUS can include the following: knowledge-based questions, image acquisition using task-specific checklists on human or simulation models, image interpretation using a series of videos or still images with normal and abnormal findings, clinical integration using “next best step” in a multiple choice format with POCUS images, and simulation-based clinical scenarios. Assessment methods should be aligned with local availability of resources and trainers.
Basic Knowledge
Basic knowledge can be assessed via multiple choice questions assessing knowledge of ultrasound physics, image optimization, relevant anatomy, and limitations of POCUS imaging. Basic knowledge lies primarily in the cognitive domain and does not assess manual skills.
Image Acquisition
Image acquisition can be assessed by observation and rating of image quality. Where resources allow, assessment of image acquisition is likely best done through a combination of developing an image portfolio with a minimum number of high quality images, plus direct observation of image acquisition by an expert. Various programs have utilized minimum numbers of images acquired to help define competence with image acquisition skills.6–8 Although minimums may be a necessary step to gain competence, using them as a sole means to determine competence does not account for variable learning curves.9 As with other manual skills in hospital medicine, such as ultrasound-guided bedside procedures, minimum numbers are best used as a starting point for assessments.3,10 In this regard, portfolio development with meticulous attention to the gain, depth, and proper tomographic plane of images can monitor a hospitalist’s progress toward competence by providing objective assessments and feedback. Simulation may also be used as it allows assessment of image acquisition skills and an opportunity to provide real-time feedback, similar to direct observation but without actual patients.
Image Interpretation
Image interpretation is best assessed by an expert observing the learner at bedside; however, when bedside assessment is not possible, image interpretation skills may be assessed using multiple choice or free text interpretation of archived ultrasound images with normal and abnormal findings. This is often incorporated into the portfolio development portion of a training program, as learners can submit their image interpretation along with the video clip. Both normal and abnormal images can be used to assess anatomic recognition and interpretation. Emphasis should be placed on determining when an image is suboptimal for diagnosis (eg, incomplete exam or poor-quality images). Quality assurance programs should incorporate structured feedback sessions.
Clinical Integration
Assessment of clinical integration can be completed through case scenarios that assess knowledge, interpretation of images, and integration of findings into clinical decision making, which is often delivered via a computer-based assessment. Assessments should combine specific POCUS applications to evaluate common clinical problems in hospital medicine, such as undifferentiated hypotension and dyspnea. High-fidelity simulators can be used to blend clinical case scenarios with image acquisition, image interpretation, and clinical integration. When feasible, comprehensive feedback on how providers acquire, interpret, and apply ultrasound at the bedside is likely the best mechanism to assess clinical integration. This process can be done with a hospitalist’s own patients.
General Assessment
A general assessment that includes a summative knowledge and hands-on skills assessment using task-specific checklists can be performed upon completion of training. A high-fidelity simulator with dynamic or virtual anatomy can provide reproducible standardized assessments with variation in the type and difficulty of cases. When available, we encourage the use of dynamic assessments on actual patients that have both normal and abnormal ultrasound findings because simulated patient scenarios have limitations, even with the use of high-fidelity simulators. Programs are recommended to use formative and summative assessments for evaluation. Quantitative scoring systems using checklists are likely the best framework.11,12
CERTIFICATES AND CERTIFICATION
A certificate of completion is proof of a provider’s participation in an educational activity; it does not equate with competency, though it may be a step toward it. Most POCUS training workshops and short courses provide certificates of completion. Certification of competency is an attestation of a hospitalist’s basic competence within a defined scope of practice (Table 2).13 However, without longitudinal supervision and feedback, skills can decay; therefore, we recommend a longitudinal training program that provides mentored feedback and incorporates periodic competency assessments. At present, no national board certification in POCUS is available to grant external certification of competency for hospitalists.
External Certificate
Certificates of completion can be external through a national organization. An external certificate of completion designed for hospitalists includes the POCUS Certificate of Completion offered by SHM in collaboration with CHEST.6 This certificate program provides regional training options and longitudinal portfolio development. Other external certificates are also available to hospitalists.7,14,15
Most hospitalists are boarded by the American Board of Internal Medicine or the American Board of Family Medicine. These boards do not yet include certification of competency in POCUS. Other specialty boards, such as emergency medicine, include competency in POCUS. For emergency medicine, completion of an accredited residency training program and certification by the national board includes POCUS competency.
Internal Certificate
There are a few examples of successful local institutional programs that have provided internal certificates of competency.12,14 Competency assessments require significant resources including investment by both faculty and learners. Ongoing evaluation of competency should be based on quality assurance processes.
Credentialing and Privileging
The American Medical Association (AMA) House of Delegates in 1999 passed a resolution (AMA HR. 802) recommending hospitals follow specialty-specific guidelines for privileging decisions related to POCUS use.17 The resolution included a statement that, “ultrasound imaging is within the scope of practice of appropriately trained physicians.”
Some institutions have begun to rely on a combination of internal and external certificate programs to grant privileges to hospitalists.10 Although specific privileges for POCUS may not be required in some hospitals, some institutions may require certification of training and assessments prior to granting permission to use POCUS.
Hospitalist programs are encouraged to evaluate ongoing POCUS use by their providers after granting initial permission. If privileging is instituted by a hospital, hospitalists must play a significant role in determining the requirements for privileging and ongoing maintenance of skills.
Maintenance of Skills
All medical skills can decay with disuse, including those associated with POCUS.12,18 Thus, POCUS users should continue using POCUS regularly in clinical practice and participate in POCUS continuing medical education activities, ideally with ongoing assessments. Maintenance of skills may be confirmed through routine participation in a quality assurance program.
PROGRAM MANAGEMENT
Use of POCUS in hospital medicine has unique considerations, and hospitalists should be integrally involved in decision making surrounding institutional POCUS program management. Appointing a dedicated POCUS director can help a program succeed.8
Equipment and Image Archiving
Several factors are important to consider when selecting an ultrasound machine: portability, screen size, and ease of use; integration with the electronic medical record and options for image archiving; manufacturer’s service plan, including technical and clinical support; and compliance with local infection control policies. The ability to easily archive and retrieve images is essential for quality assurance, continuing education, institutional quality improvement, documentation, and reimbursement. In certain scenarios, image archiving may not be possible (such as with personal handheld devices or in emergency situations) or necessary (such as with frequent serial examinations during fluid resuscitation). An image archive is ideally linked to reports, orders, and billing software.10,19 If such linkages are not feasible, parallel external storage that complies with regulatory standards (ie, HIPAA compliance) may be suitable.20
Documentation and Billing
Components of documentation include the indication and type of ultrasound examination performed, date and time of the examination, patient identifying information, name of provider(s) acquiring and interpreting the images, specific scanning protocols used, patient position, probe used, and findings. Documentation can occur through a standalone note or as part of another note, such as a progress note. Whenever possible, documentation should be timely to facilitate communication with other providers.
Billing is supported through the AMA Current Procedural Terminology codes for “focused” or “limited” ultrasound examinations (Appendix 9). The following three criteria must be satisfied for billing. First, images must be permanently stored. Specific requirements vary by insurance policy, though current practice suggests a minimum of one image demonstrating relevant anatomy and pathology for the ultrasound examination coded. For ultrasound-guided procedures that require needle insertion, images should be captured at the point of interest, and a procedure note should reflect that the needle was guided and visualized under ultrasound.21 Second, proper documentation must be entered in the medical record. Third, local institutional privileges for POCUS must be considered. Although privileges are not required to bill, some hospitals or payers may require them.
Quality Assurance
Published guidelines on quality assurance in POCUS are available from different specialty organizations, including emergency medicine, pediatric emergency medicine, critical care, anesthesiology, obstetrics, and cardiology.8,22–28 Quality assurance is aimed at ensuring that physicians maintain basic competency in using POCUS to influence bedside decisions.
Quality assurance should be carried out by an individual or committee with expertise in POCUS. Multidisciplinary QA programs in which hospital medicine providers are working collaboratively with other POCUS providers have been demonstrated to be highly effective.10 Oversight includes ensuring that providers using POCUS are appropriately trained,10,22,28 using the equipment correctly,8,26,28 and documenting properly. Some programs have implemented mechanisms to review and provide feedback on image acquisition, interpretation, and clinical integration.8,10 Other programs have compared POCUS findings with referral studies, such as comprehensive ultrasound examinations.
CONCLUSIONS
Practicing hospitalists must continue to collaborate with their institutions to build POCUS capabilities. In particular, they must work with their local privileging body to determine what credentials are required. The distinction between certificates of completion and certificates of competency, including whether those certificates are internal or external, is important in the credentialing process.
External certificates of competency are currently unavailable for most practicing hospitalists because ABIM certification does not include POCUS-related competencies. As internal medicine residency training programs begin to adopt POCUS training and certification into their educational curricula, we foresee a need to update the ABIM Policies and Procedures for Certification. Until then, we recommend that certificates of competency be defined and granted internally by local hospitalist groups.
Given the many advantages of POCUS over traditional tools, we anticipate its increasing implementation among hospitalists in the future. As with all medical technology, its role in clinical care should be continuously reexamined and redefined through health services research. Such information will be useful in developing practice guidelines, educational curricula, and training standards.
Acknowledgments
The authors would like to thank all members that participated in the discussion and finalization of this position statement during the Point-of-care Ultrasound Faculty Retreat at the 2018 Society of Hospital Medicine Annual Conference: Saaid Abdel-Ghani, Brandon Boesch, Joel Cho, Ria Dancel, Renee Dversdal, Ricardo Franco-Sadud, Benjamin Galen, Trevor P. Jensen, Mohit Jindal, Gordon Johnson, Linda M. Kurian, Gigi Liu, Charles M. LoPresti, Brian P. Lucas, Venkat Kalidindi, Benji Matthews, Anna Maw, Gregory Mints, Kreegan Reierson, Gerard Salame, Richard Schildhouse, Daniel Schnobrich, Nilam Soni, Kirk Spencer, Hiromizu Takahashi, David M. Tierney, Tanping Wong, and Toru Yamada.
1. Schnobrich DJ, Mathews BK, Trappey BE, Muthyala BK, Olson APJ. Entrusting internal medicine residents to use point of care ultrasound: Towards improved assessment and supervision. Med Teach. 2018:1-6. doi:10.1080/0142159X.2018.1457210.
2. Soni NJ, Lucas BP. Diagnostic point-of-care ultrasound for hospitalists. J Hosp Med. 2015;10(2):120-124. doi:10.1002/jhm.2285.
3. Lucas BP, Tierney DM, Jensen TP, et al. Credentialing of hospitalists in ultrasound-guided bedside procedures: a position statement of the society of hospital medicine. J Hosp Med. 2018;13(2):117-125. doi:10.12788/jhm.2917.
4. Dancel R, Schnobrich D, Puri N, et al. Recommendations on the use of ultrasound guidance for adult thoracentesis: a position statement of the society of hospital medicine. J Hosp Med. 2018;13(2):126-135. doi:10.12788/jhm.2940.
5. National Council on Radiation Protection and Measurements, The Council. Implementation of the Principle of as Low as Reasonably Achievable (ALARA) for Medical and Dental Personnel.; 1990.
6. Society of Hospital Medicine. Point of Care Ultrasound course: https://www.hospitalmedicine.org/clinical-topics/ultrasonography-cert/. Accessed February 6, 2018.
7. Critical Care Ultrasonography Certificate of Completion Program. CHEST. American College of Chest Physicians. http://www.chestnet.org/Education/Advanced-Clinical-Training/Certificate-of-Completion-Program/Critical-Care-Ultrasonography. Accessed February 6, 2018.
8. American College of Emergency Physicians Policy Statement: Emergency Ultrasound Guidelines. 2016. https://www.acep.org/Clinical---Practice-Management/ACEP-Ultrasound-Guidelines/. Accessed February 6, 2018.
9. Blehar DJ, Barton B, Gaspari RJ. Learning curves in emergency ultrasound education. Acad Emerg Med. 2015;22(5):574-582. doi:10.1111/acem.12653.
10. Mathews BK, Zwank M. Hospital medicine point of care ultrasound credentialing: an example protocol. J Hosp Med. 2017;12(9):767-772. doi:10.12788/jhm.2809.
11. Barsuk JH, McGaghie WC, Cohen ER, Balachandran JS, Wayne DB. Use of simulation-based mastery learning to improve the quality of central venous catheter placement in a medical intensive care unit. J Hosp Med. 2009;4(7):397-403. doi:10.1002/jhm.468.
12. Mathews BK, Reierson K, Vuong K, et al. The design and evaluation of the Comprehensive Hospitalist Assessment and Mentorship with Portfolios (CHAMP) ultrasound program. J Hosp Med. 2018;13(8):544-550. doi:10.12788/jhm.2938.
13. Soni NJ, Tierney DM, Jensen TP, Lucas BP. Certification of point-of-care ultrasound competency. J Hosp Med. 2017;12(9):775-776. doi:10.12788/jhm.2812.
14. Ultrasound Certification for Physicians. Alliance for Physician Certification and Advancement. APCA. https://apca.org/. Accessed February 6, 2018.
15. National Board of Echocardiography, Inc. https://www.echoboards.org/EchoBoards/News/2019_Adult_Critical_Care_Echocardiography_Exam.aspx. Accessed June 18, 2018.
16. Tierney DM. Internal Medicine Bedside Ultrasound Program (IMBUS). Abbott Northwestern. http://imbus.anwresidency.com/index.html. Accessed February 6, 2018.
17. American Medical Association House of Delegates Resolution H-230.960: Privileging for Ultrasound Imaging. Resolution 802. Policy Finder Website. http://search0.ama-assn.org/search/pfonline. Published 1999. Accessed February 18, 2018.
18. Kelm D, Ratelle J, Azeem N, et al. Longitudinal ultrasound curriculum improves long-term retention among internal medicine residents. J Grad Med Educ. 2015;7(3):454-457. doi:10.4300/JGME-14-00284.1.
19. Flannigan MJ, Adhikari S. Point-of-care ultrasound work flow innovation: impact on documentation and billing. J Ultrasound Med. 2017;36(12):2467-2474. doi:10.1002/jum.14284.
20. Emergency Ultrasound: Workflow White Paper. https://www.acep.org/uploadedFiles/ACEP/memberCenter/SectionsofMembership/ultra/Workflow%20White%20Paper.pdf. Published 2013. Accessed February 18, 2018.
21. Ultrasound Coding and Reimbursement Document 2009. Emergency Ultrasound Section. American College of Emergency Physicians. http://emergencyultrasoundteaching.com/assets/2009_coding_update.pdf. Published 2009. Accessed February 18, 2018.
22. Mayo PH, Beaulieu Y, Doelken P, et al. American College of Chest Physicians/La Societe de Reanimation de Langue Francaise statement on competence in critical care ultrasonography. Chest. 2009;135(4):1050-1060. doi:10.1378/chest.08-2305.
23. Frankel HL, Kirkpatrick AW, Elbarbary M, et al. Guidelines for the appropriate use of bedside general and cardiac ultrasonography in the evaluation of critically ill patients-part I: general ultrasonography. Crit Care Med. 2015;43(11):2479-2502. doi:10.1097/ccm.0000000000001216.
24. Levitov A, Frankel HL, Blaivas M, et al. Guidelines for the appropriate use of bedside general and cardiac ultrasonography in the evaluation of critically ill patients-part ii: cardiac ultrasonography. Crit Care Med. 2016;44(6):1206-1227. doi:10.1097/ccm.0000000000001847.
25. ACR–ACOG–AIUM–SRU Practice Parameter for the Performance of Obstetrical Ultrasound. https://www.acr.org/-/media/ACR/Files/Practice-Parameters/us-ob.pdf. Published 2013. Accessed February 18, 2018.
26. AIUM practice guideline for documentation of an ultrasound examination. J Ultrasound Med. 2014;33(6):1098-1102. doi:10.7863/ultra.33.6.1098.
27. Marin JR, Lewiss RE. Point-of-care ultrasonography by pediatric emergency medicine physicians. Pediatrics. 2015;135(4):e1113-e1122. doi:10.1542/peds.2015-0343.
28. Spencer KT, Kimura BJ, Korcarz CE, Pellikka PA, Rahko PS, Siegel RJ. Focused cardiac ultrasound: recommendations from the American Society of Echocardiography. J Am Soc Echocardiogr. 2013;26(6):567-581. doi:10.1016/j.echo.2013.04.001.
1. Schnobrich DJ, Mathews BK, Trappey BE, Muthyala BK, Olson APJ. Entrusting internal medicine residents to use point of care ultrasound: Towards improved assessment and supervision. Med Teach. 2018:1-6. doi:10.1080/0142159X.2018.1457210.
2. Soni NJ, Lucas BP. Diagnostic point-of-care ultrasound for hospitalists. J Hosp Med. 2015;10(2):120-124. doi:10.1002/jhm.2285.
3. Lucas BP, Tierney DM, Jensen TP, et al. Credentialing of hospitalists in ultrasound-guided bedside procedures: a position statement of the society of hospital medicine. J Hosp Med. 2018;13(2):117-125. doi:10.12788/jhm.2917.
4. Dancel R, Schnobrich D, Puri N, et al. Recommendations on the use of ultrasound guidance for adult thoracentesis: a position statement of the society of hospital medicine. J Hosp Med. 2018;13(2):126-135. doi:10.12788/jhm.2940.
5. National Council on Radiation Protection and Measurements, The Council. Implementation of the Principle of as Low as Reasonably Achievable (ALARA) for Medical and Dental Personnel.; 1990.
6. Society of Hospital Medicine. Point of Care Ultrasound course: https://www.hospitalmedicine.org/clinical-topics/ultrasonography-cert/. Accessed February 6, 2018.
7. Critical Care Ultrasonography Certificate of Completion Program. CHEST. American College of Chest Physicians. http://www.chestnet.org/Education/Advanced-Clinical-Training/Certificate-of-Completion-Program/Critical-Care-Ultrasonography. Accessed February 6, 2018.
8. American College of Emergency Physicians Policy Statement: Emergency Ultrasound Guidelines. 2016. https://www.acep.org/Clinical---Practice-Management/ACEP-Ultrasound-Guidelines/. Accessed February 6, 2018.
9. Blehar DJ, Barton B, Gaspari RJ. Learning curves in emergency ultrasound education. Acad Emerg Med. 2015;22(5):574-582. doi:10.1111/acem.12653.
10. Mathews BK, Zwank M. Hospital medicine point of care ultrasound credentialing: an example protocol. J Hosp Med. 2017;12(9):767-772. doi:10.12788/jhm.2809.
11. Barsuk JH, McGaghie WC, Cohen ER, Balachandran JS, Wayne DB. Use of simulation-based mastery learning to improve the quality of central venous catheter placement in a medical intensive care unit. J Hosp Med. 2009;4(7):397-403. doi:10.1002/jhm.468.
12. Mathews BK, Reierson K, Vuong K, et al. The design and evaluation of the Comprehensive Hospitalist Assessment and Mentorship with Portfolios (CHAMP) ultrasound program. J Hosp Med. 2018;13(8):544-550. doi:10.12788/jhm.2938.
13. Soni NJ, Tierney DM, Jensen TP, Lucas BP. Certification of point-of-care ultrasound competency. J Hosp Med. 2017;12(9):775-776. doi:10.12788/jhm.2812.
14. Ultrasound Certification for Physicians. Alliance for Physician Certification and Advancement. APCA. https://apca.org/. Accessed February 6, 2018.
15. National Board of Echocardiography, Inc. https://www.echoboards.org/EchoBoards/News/2019_Adult_Critical_Care_Echocardiography_Exam.aspx. Accessed June 18, 2018.
16. Tierney DM. Internal Medicine Bedside Ultrasound Program (IMBUS). Abbott Northwestern. http://imbus.anwresidency.com/index.html. Accessed February 6, 2018.
17. American Medical Association House of Delegates Resolution H-230.960: Privileging for Ultrasound Imaging. Resolution 802. Policy Finder Website. http://search0.ama-assn.org/search/pfonline. Published 1999. Accessed February 18, 2018.
18. Kelm D, Ratelle J, Azeem N, et al. Longitudinal ultrasound curriculum improves long-term retention among internal medicine residents. J Grad Med Educ. 2015;7(3):454-457. doi:10.4300/JGME-14-00284.1.
19. Flannigan MJ, Adhikari S. Point-of-care ultrasound work flow innovation: impact on documentation and billing. J Ultrasound Med. 2017;36(12):2467-2474. doi:10.1002/jum.14284.
20. Emergency Ultrasound: Workflow White Paper. https://www.acep.org/uploadedFiles/ACEP/memberCenter/SectionsofMembership/ultra/Workflow%20White%20Paper.pdf. Published 2013. Accessed February 18, 2018.
21. Ultrasound Coding and Reimbursement Document 2009. Emergency Ultrasound Section. American College of Emergency Physicians. http://emergencyultrasoundteaching.com/assets/2009_coding_update.pdf. Published 2009. Accessed February 18, 2018.
22. Mayo PH, Beaulieu Y, Doelken P, et al. American College of Chest Physicians/La Societe de Reanimation de Langue Francaise statement on competence in critical care ultrasonography. Chest. 2009;135(4):1050-1060. doi:10.1378/chest.08-2305.
23. Frankel HL, Kirkpatrick AW, Elbarbary M, et al. Guidelines for the appropriate use of bedside general and cardiac ultrasonography in the evaluation of critically ill patients-part I: general ultrasonography. Crit Care Med. 2015;43(11):2479-2502. doi:10.1097/ccm.0000000000001216.
24. Levitov A, Frankel HL, Blaivas M, et al. Guidelines for the appropriate use of bedside general and cardiac ultrasonography in the evaluation of critically ill patients-part ii: cardiac ultrasonography. Crit Care Med. 2016;44(6):1206-1227. doi:10.1097/ccm.0000000000001847.
25. ACR–ACOG–AIUM–SRU Practice Parameter for the Performance of Obstetrical Ultrasound. https://www.acr.org/-/media/ACR/Files/Practice-Parameters/us-ob.pdf. Published 2013. Accessed February 18, 2018.
26. AIUM practice guideline for documentation of an ultrasound examination. J Ultrasound Med. 2014;33(6):1098-1102. doi:10.7863/ultra.33.6.1098.
27. Marin JR, Lewiss RE. Point-of-care ultrasonography by pediatric emergency medicine physicians. Pediatrics. 2015;135(4):e1113-e1122. doi:10.1542/peds.2015-0343.
28. Spencer KT, Kimura BJ, Korcarz CE, Pellikka PA, Rahko PS, Siegel RJ. Focused cardiac ultrasound: recommendations from the American Society of Echocardiography. J Am Soc Echocardiogr. 2013;26(6):567-581. doi:10.1016/j.echo.2013.04.001.
© 2019 Society of Hospital Medicine
Accuracy of Hospitalist‐Performed HCUE
Hand‐carried ultrasound echocardiography (HCUE) can help noncardiologists answer well‐defined questions at patients' bedsides in less than 10 minutes.1, 2 Indeed, intensivists3 and emergency department physicians4 already use HCUE to make rapid, point‐of‐care assessments. Since cardiovascular diagnoses are common among general medicine inpatients, HCUE may become an important skill for hospitalists to learn.5
However, uncertainty exists about the duration of HCUE training for hospitalists. In 2002, experts from the American Society of Echocardiography (ASE) published recommendations on training requirements for HCUE.6 With limited data on the safety or performance of HCUE training programs, which had just begun to emerge, the ASE borrowed from the proven training recommendations for standard echocardiography (SE). They recommended that all HCUE trainees, cardiologist and noncardiologist alike, complete level 1 SE training: 75 personally‐performed and 150 personally‐interpreted echocardiographic examinations. Since then, however, several HCUE training programs designed for noncardiologists have emerged.2, 5, 710 These alternative programs suggest that the ASE's recommended duration of training may be too long, particularly for focused HCUE that is limited to a few relatively simple assessments. It is important not to overshoot the requirements of HCUE training, because doing so may discourage groups of noncardiologists, like hospitalists, who may derive great benefits from HCUE.11
To address this uncertainty for hospitalists, we first developed a brief HCUE training program to assess 6 important cardiac abnormalities. We then studied the diagnostic accuracy of HCUE by hospitalists as a test of these 6 cardiac abnormalities assessed by SE.
Patients and Methods
Setting and Subjects
This prospective cohort study was performed at Stroger Hospital of Cook County, a 500‐bed public teaching hospital in Chicago, IL, from March through May of 2007. The cohort was adult inpatients who were referred for SE on weekdays from 3 distinct patient care units (Figure 1). We used 2 sampling modes to balance practical constraints (short‐stay unit [SSU] patients were more localized and, therefore, easier to study) with clinical diversity. We consecutively sampled patients from our SSU, where adults with provisional cardiovascular diagnoses are admitted if they might be eligible for discharge with in 3 days.12 But we used random number tables with a daily unique starting point to randomly sample patients from the general medical wards and the coronary care unit (CCU). Patients were excluded if repositioning them for HCUE was potentially harmful. The study was approved by our hospital's institutional review board, and we obtained written informed consent from all enrolled patients.
SE Protocol
As part of enrolled patients' routine clinical care, SE images were acquired and interpreted in the usual fashion in our hospital's echocardiography laboratory, which performs SE on over 7,000 patients per year. Echocardiographic technicians acquired images with a General Electric Vivid 7 cardiac ultrasound machine (General Electric, Milwaukee, WI) equipped with a GE M4S 1.8 to 3.4 MHz cardiac transducer (General Electric). Technicians followed the standard adult transthoracic echocardiography scanning protocol to acquire 40 to 100 images on every patient using all available echocardiographic modalities: 2‐dimensional, M‐mode, color Doppler, continuous‐wave Doppler, pulse‐wave Doppler, and tissue Doppler.13 Blinded to HCUE results, attending physician cardiologist echocardiographers then interpreted archived images using computer software (Centricity System; General Electric) to generate final reports that were entered into patients' medical records. This software ensured that final reports were standardized, because echocardiographers' final qualitative assessments were limited to short lists of standard options; for example, in reporting left atrium (LA) size, echocardiographers chose from only 5 standard options: normal, mildly dilated, moderately dilated, severely dilated, and not interpretable. Investigators, who were also blinded to HCUE results, later abstracted SE results from these standardized report forms in patients' medical records. All echocardiographers fulfilled ASE training guidelines to independently interpret SE: a minimum of 150 personally‐performed and 300 personally‐interpreted echocardiographic examinations (training level 2).14
HCUE Training
Based on the recommendations of our cardiologist investigator (B.M.), we developed a training program for 1 hospitalist to become an HCUE instructor. Our instructor trainee (C.C.) was board‐eligible in internal medicine but had no previous formal training in cardiology or echocardiography. We a priori established that her training would continue until our cardiologist investigator determined that she was ready to train other hospitalists; this determination occurred after 5 weeks. She learned image acquisition by performing focused SE on 30 patients under the direct supervision of an echocardiographic technician. She also performed focused HCUE on 65 inpatients without direct supervision but with ongoing access to consult the technician to review archived images and troubleshoot difficulties with acquisition. She learned image interpretation by reading relevant chapters from a SE textbook15 and by participating in daily didactic sessions in which attending cardiologist echocardiographers train cardiology fellows in SE interpretation.
This hospitalist then served as the HCUE instructor for 8 other attending physician hospitalists who were board‐certified internists with no previous formal training in cardiology or echocardiography. The training program was limited to acquisition and interpretation of 2‐dimensional grayscale and color Doppler images for the 6 cardiac assessments under study (Table 1). The instructor marshaled pairs of hospitalists through the 3 components of the training program, which lasted a total of 27 hours.
|
| Six cardiac assessments learned using 2‐dimensional gray scale and color Doppler imaging |
| Left ventricular systolic dysfunction |
| Mitral valve regurgitation |
| Left atrium enlargement |
| Left ventricular hypertrophy |
| Pericardial effusion |
| Inferior vena cava diameter |
| Lecture (2 hours)* |
| Basic principles of echocardiography |
| HCUE scanning protocol and helpful techniques to optimize image quality |
| Hands‐on training with instructor |
| Orientation to machine and demonstration of scanning protocol (1 hour) |
| Sessions 1 through 3: HCUE performed on 1 patient per hour (6 patients in 6 hours) |
| Sessions 4 through 10: HCUE performed on 2 patients per hour (28 patients in 14 hours) |
| Feedback sessions on image quality and interpretation with cardiologist |
| After hands‐on training session 3 (2 hours) |
| After hands‐on training session 10 (2 hours) |
First, hospitalists attended a 2‐hour lecture on the basic principles of HCUE. Slides from this lecture and additional images of normal and abnormal findings were provided to each hospitalist on a digital video disc. Second, each hospitalist underwent 20 hours of hands‐on training in 2‐hour sessions scheduled over 2 weeks. Willing inpatients from our hospital's emergency department were used as volunteers for these hand‐on training sessions. During these sessions the instructor provided practical suggestions to optimize image quality, such as transducer location and patient positioning. In the first 3 sessions, the minimum pace was 1 patient per hour; thereafter, the pace was increased to 1 patient per half‐hour. We chose 20 hours of hands‐on training and these minimum paces because they allowed each hospitalist to attain a cumulative experience of no less than 30 patientsan amount that heralds a flattening of the HCUE learning curve among medical trainees.9 Third, each pair of hospitalists received feedback from a cardiologist investigator (B.M.) who critiqued the quality and interpretation of images acquired by hospitalists during hands‐on training sessions. Since image quality varies by patient,16 hospitalists' images were compared side‐by‐side to images recorded by the instructor on the same patients. The cardiologist also critiqued hospitalists' interpretations of both their own images and additional sets of archived images from patients with abnormal findings.
HCUE Protocol
After completing the training program and blinded to the results of SE, the 8 hospitalists performed HCUE on enrolled patients within hours of SE. We limited the time interval between tests to minimize the effect that changes in physiologic variables, such as blood pressure and intravascular volume, have on the reliability of serial echocardiographic measurements.16 Hospitalists performed HCUE with a MicroMaxx 3.4 hand‐carried ultrasound machine equipped with a cardiology software package and a 1 to 5 MHz P17 cardiac transducer (Sonosite, Inc., Bothell, WA); simultaneous electrocardiographic recording, though available, was not used. While patients laid on their own standard hospital beds or on a standard hospital gurney in a room adjacent to the SE waiting room, hospitalists positioned them without assistance from nursing staff and recorded 7 best‐quality images per patient. Patients were first positioned in a partial (3045 degrees) left lateral decubitus position to record 4 grayscale images of the short‐axis and long‐axis parasternal and 2‐chamber and 4‐chamber apical views; 2 color Doppler images of the mitral inflow were also recorded from the long‐axis parasternal and the 4‐chamber apical views. Patients were then positioned supine to record 1 grayscale image of the inferior vena cava (IVC) from the transhepatic view. Hospitalists did not perform a history or physical exam on enrolled patients, nor did they review patients' medical records.
Immediately following the HCUE, hospitalists replayed the recorded images as often as needed and entered final interpretations on data collection forms. Linear measurements were made manually with a caliper held directly to the hand‐carried ultrasound monitor. These measurements were then translated into qualitative assessments based on standard values used by our hospital's echocardiographers (Table 2).17 When a hospitalist could not confidently assess a cardiac abnormality, the final HCUE assessment was recorded as indeterminate. Hospitalists also recorded the time to perform each HCUE, which included the time to record 7 best‐quality images, to interpret the findings, and to fill out the data collection form.
| Hand‐Carried Ultrasound Echocardiography Results | |||||
|---|---|---|---|---|---|
| Cardiac Abnormality by Standard Echocardiography | Hand‐Carried Ultrasound Echocardiography Operator's Method of Assessment | Positive | Negative | ||
| |||||
| Left ventricle systolic dysfunction, mild or greater | Grade degree of abnormal wall movement and thickening during systole | Severe | Mild or moderate | Normal | Vigorous |
| Mitral valve regurgitation, severe | Classify regurgitant jet as central or eccentric, then measure as percentage of left atrium area | ||||
| Central jet | 20% | <20% | |||
| Eccentric jet | 20% | indeterminate 20% | |||
| Left atrium enlargement, moderate or severe | Measure left atrium in 3 dimensions at end diastole, then use the most abnormal dimension | Extreme | Borderline | ||
| Anteroposterior or mediolateral (cm) | 5.1 | 4.55.0 | 4.4 | ||
| Superior‐inferior (cm) | 7.1 | 6.17.0 | 6.0 | ||
| Left ventricle hypertrophy, moderate or severe | Measure thickest dimension of posterior or septal wall at end diastole | Extreme: 1.4 cm | Borderline: 1.21.3 cm | 1.1 cm | |
| Pericardial effusion, medium or large | Measure largest dimension in any view at end diastole | 1 cm | <1 cm | ||
| Inferior vena cava dilatation | Measure largest respirophasic diameter within 2 cm of right atrium | 2.1 cm | Normal: 1 to 2 cm | Contracted: 0.9 cm | |
Data Analysis
We based our sample size calculations on earlier reports of HCUE by noncardiologist trainees for assessment of left ventricular (LV) systolic function.7, 10 From these reports, we estimated a negative likelihood ratio of 0.3. In addition, we expected about a quarter of our patients to have LV systolic dysfunction (B.M., personal communication). Therefore, to achieve 95% confidence intervals (CIs) around the point estimate of a negative likelihood ratio that excluded 0.50, our upper bound for a clinically meaningful result, we needed a sample size of approximately 300 patients.18
We defined threshold levels of ordinal severity for the 6 cardiac abnormalities under study based on their clinical pertinence to hospitalists (Table 2). Here, we reasoned that abnormalities at or above these levels would likely lead to important changes in hospitalists' management of inpatients; abnormalities below these levels rarely represent cardiac disease that is worthy of an immediate change in management. Since even mild degrees of LV dysfunction have important diagnostic and therapeutic implications for most general medicine inpatients, particularly those presenting with heart failure,19 we set our threshold for LV dysfunction at mild or greater. In contrast, since neither mild nor moderate mitral regurgitation (MR) has immediate implications for medical or surgical therapy even if symptoms or LV dysfunction are present,20 we set our threshold for MR at severe. Similarly, though mild LA enlargement21 and mild LV hypertrophy22 have clear prognostic implications for patients' chronic medical conditions, we reasoned that only moderate or severe versions likely reflect underlying abnormalities that affect hospitalists' point‐of‐care decision‐making. Since cardiac tamponade is rarely both subclinical23 and due to a small pericardial effusion,24 we set our threshold for pericardial effusion size at moderate or large. Finally, we set our threshold IVC diameter, a marker of central venous volume status,25 at dilated, because volume overload is an important consideration in hospitalized cardiac patients.
Using these thresholds, investigators dichotomized echocardiographers' SE readings as normal or abnormal for each of the 6 cardiac abnormalities under study to serve as the reference standards. Hospitalists' HCUE results were then compared to the reference standards in 2 different ways. We first analyzed HCUE results as dichotomous values to calculate conventional sensitivity, specificity, and positive and negative likelihood ratios. Here we considered indeterminate HCUE results positive in a clinically conservative tradeoff that neither ignores indeterminate results nor risks falsely classifying them as negative.26 We then analyzed hospitalists' HCUE results as ordinal values for receiver operating characteristic (ROC) curve analysis. Here we considered an indeterminate result as 1 possible test result.27
To examine interobserver variability of HCUE, we first chose from the 6 possible assessments only those with a mean number of abnormal patients per hospitalist greater than 5. We reasoned that variability among assessments with lower prevalence would be predictably wide and inconclusive. We then expressed variability as standard deviations (SDs) around mean sensitivity and specificity for the 8 hospitalists.
The CIs for likelihood ratios were constructed using the likelihood‐based approach to binomial proportions of Koopman.28 The areas under ROC curves were computed using the trapezoidal rule, and the CIs for these areas were constructed using the algorithm described by DeLong et al.29 All analyses were conducted with Stata Statistical Software, Release 10 (StataCorp, College Station, TX).
Results
During the 3 month study period, 654 patients were referred for SE from the 3 participating patient care units (Figure 1). Among these, 65 patients were ineligible because their SE was performed on the weekend and 178 other patients were not randomized from the general medical wards and CCU. From the remaining eligible patients, 322 underwent HCUE and 314 (98% of 322) underwent both SE and HCUE. Individual SE assessments were not interpretable (and therefore excluded) due to poor image quality for LA enlargement in 1 patient and IVC dilatation in 30 patients. Eighty‐three percent of patients who underwent SE (260/314) were referred to assess LV function (Table 3). The prevalence of the 6 clinically pertinent cardiac abnormalities under study ranged from 1% for moderate or large pericardial effusion to 25% for LV systolic dysfunction. Overall, 40% of patients had at least 1 out of 6 cardiac abnormalities.
| Characteristic | |
|---|---|
| |
| Age, year SD (25th to 75th percentiles) | 56 13 (48 to 64) |
| Women | 146 (47) |
| Chronic obstructive pulmonary disease | 47 (15) |
| Body mass index | |
| 24.9 or less: underweight or normal | 74 (24) |
| 25 to 29.9: overweight | 94 (30) |
| 30 to 34.9: mild obesity | 75 (24) |
| 35 or greater: moderate or severe obesity | 71 (23) |
| Patient care unit | |
| Short‐stay unit | 175 (56) |
| General medical wards | 89 (28) |
| Cardiac care unit | 50 (16) |
| Indication for standard echocardiography* | |
| Left ventricular function | 260 (83) |
| Valvular function | 56 (18) |
| Wall motion abnormality | 29 (9) |
| Valvular vegetations | 22 (7) |
| Any structural heart disease | 20 (6) |
| Right ventricular function | 18 (6) |
| Other | 38 (12) |
| Standard echocardiography findings | |
| Left ventricular systolic dysfunction mild | 80 (25) |
| Inferior vena cava dilated | 45 (14) |
| Left ventricular wall thickness moderate | 33 (11) |
| Left atrium enlargement moderate | 19 (6) |
| Mitral valve regurgitation severe | 11 (4) |
| Pericardial effusion moderate | 3 (1) |
| At least 1 of the above findings | 127 (40) |
| Time difference between HCUE and standard echocardiogram, median hours (25th to 75th percentiles) | 2.8 (1.4 to 5.1) |
| Time to complete HCUE, median minutes (25th to 75th percentiles) | 28 (20 to 35) |
Each hospitalist performed a similar total number of HCUE examinations (range, 3447). The median time difference between performance of SE and HCUE was 2.8 hours (25th75th percentiles, 1.45.1). Despite the high prevalence of chronic obstructive pulmonary disease and obesity, hospitalists considered HCUE assessments indeterminate in only 2% to 6% of the 6 assessments made for each patient (Table 4). Among the 38 patients (12% of 322) with any indeterminate HCUE assessment, 24 patients had only 1 out of 6 possible. Hospitalists completed HCUE in a median time of 28 minutes (25th‐75th percentiles, 2035), which included the time to record 7 best‐quality moving images and to fill out the research data collection form.
| n (%)* | |
|---|---|
| |
| Number of indeterminate findings per patient | |
| 0 | 284 (88) |
| 1 | 24 (7) |
| 2 | 4 (1) |
| 3 or more | 10 (3) |
| Indeterminate findings by cardiac assessment | |
| Mitral valve regurgitation | 18 (6) |
| Inferior vena cava diameter | 16 (5) |
| Left ventricular hypertrophy | 15 (5) |
| Pericardial effusion | 9 (3) |
| Left atrium size | 5 (2) |
| Left ventricle systolic function | 5 (2) |
When HCUE results were analyzed as dichotomous values, positive likelihood ratios ranged from 2.5 to 21, and negative likelihood ratios ranged from 0 to 0.4 (Table 5). Positive and negative likelihood ratios were both sufficiency high and low to respectively increase and decrease by 5‐fold the prior odds of 3 out of 6 cardiac abnormalities: LV systolic dysfunction, moderate or severe MR regurgitation, and moderate or large pericardial effusion. Considering HCUE results as ordinal values for ROC analysis yielded additional diagnostic information (Figure 2). For example, the likelihood ratio of 1.0 (95% CI, 0.42.0) for borderline positive moderate or severe LA enlargement increased to 29 (range, 1362) for extreme positive results. Areas under the ROC curves were 0.9 for 4 out of 6 cardiac abnormalities.
| Clinically Pertinent Cardiac Abnormality by Standard Echocardiography | Prevalence n/total n | Sensitivity* % (95% CI) | Specificity* % (95% CI) | LRpositive*, (95% CI) | LRnegative*, (95% CI) |
|---|---|---|---|---|---|
| |||||
| Left ventricular systolic dysfunction | 80/314 | 85 (7592) | 88 (8392) | 6.9 (4.99.8) | 0.2 (0.10.3) |
| Mitral valve regurgitation, severe | 11/314 | 100 (72100) | 83 (7987) | 5.9 (3.97.4) | 0 (00.3) |
| Left atrium enlargement, moderate or severe | 19/313 | 90 (6799) | 74 (6879) | 3.4 (2.54.3) | 0.1 (0.040.4) |
| Left ventricular hypertrophy, moderate or severe | 33/314 | 70 (5184) | 73 (6778) | 2.5 (1.83.3) | 0.4 (0.20.7) |
| Pericardial effusion, moderate or large | 3/314 | 100 (29100) | 95 (9297) | 21 (6.731) | 0 (00.6) |
| Inferior vena cava, dilated | 45/284 | 56 (4070) | 86 (8190) | 4.0 (2.66.0) | 0.5 (0.40.7) |
LV systolic dysfunction and IVC dilatation were both prevalent enough to meet our criterion to examine interobserver variability; the mean number of abnormal patients per hospitalist was 10 patients for LV systolic dysfunction and 6 patients for IVC dilatation. For LV systolic dysfunction, SDs around mean sensitivity (84%) and specificity (87%) were 12% and 6%, respectively. For IVC dilatation, SDs around mean sensitivity (58%) and specificity (86%) were 24% and 7%, respectively.
Discussion
We found that, after a 27‐hour training program, hospitalists performed HCUE with moderate to excellent diagnostic accuracy for 6 important cardiac abnormalities. For example, hospitalists' assessments of LV systolic function yielded positive and negative likelihood ratios of 6.9 (95% CI, 4.99.8) and 0.2 (95% CI, 0.10.3), respectively. At the bedsides of patients with acute heart failure, therefore, hospitalists could use HCUE to lower or raise the 50:50 chance of LV systolic dysfunction30 to 15% or 85%, respectively. Whether or not these posttest likelihoods are extreme enough to cross important thresholds will depend on the clinical context. Yet these findings demonstrate how HCUE has the potential to provide hospitalists with valuable point‐of‐care data that are otherwise unavailableeither because routine clinical assessments are unreliable31 or because echocardiographic services are not immediately accessible.1
In fact, recent data from the Joint Commission on Accreditation of Healthcare Organizations shows how inaccessible SE may be. Approximately one‐quarter of hospitals in the United States send home about 10% of patients with acute heart failure without echocardiographic assessment of LV systolic function before, during, or immediately after hospitalization.32 In doing so, these hospitals leave unmet the 2002 National Quality Improvement Goal of universal assessment of LV systolic function for all heart failure patients. Hospitalists could close this quality gap with routine, 10‐minute HCUE assessments in all patients admitted with acute heart failure. (Our research HCUE protocol required a median time of 28 minutes, but this included time to assess 5 other cardiac abnormalities and collect data for research purposes). Until the clinical consequences of introducing hospitalist‐performed HCUE are studied, potential benefits like this are tentative. But our findings suggest that training hospitalists to accurately perform HCUE can be successfully accomplished in just 27 hours.
Other studies of HCUE training programs for noncardiologists have also challenged the opinion that learning to perform HCUE requires more than 100 hours of training.2, 711 Yet only 1 prior study has examined an HCUE training program for hospitalists.5 In this study by Martin et al.,5 hospitalists completed 5 supervised HCUE examinations and 6 hours of interpretation training before investigators scored their image acquisition and interpretation skills from 30 unsupervised HCUE examinations. To estimate their final skill levels at the completion of all 35 examinations by accounting for an initially steep learning curve, investigators then adjusted these scores with regression models. Despite these upward adjustments, hospitalists' image acquisition and interpretation scores were low in comparison to echocardiographic technicians and cardiology fellows. Besides these adjusted measurements of hospitalists' skills, however, Martin et al.5 unfortunately did not also report standard measures of diagnostic accuracy, like those proposed by the Standards for Reporting of Diagnostic Accuracy (STARD) initiative.33 Therefore, direct comparisons to the present study are difficult. Nevertheless, their findings suggest that a training program limited to 5 supervised HCUE examinations may be inadequate for hospitalists. In fact, the same group's earlier study of medical trainees suggested a minimum of 30 supervised HCUE examinations.9 We chose to design our hospitalist training program based on this minimum, though they surprisingly did not.5 As others continue to refine the components of hospitalist HCUE training programs, such as the optimal number of supervised examinations, our program could serve as a reasonable comparative example: more rigorous than the program designed by Martin et al.5 but more feasible than ASE level 1 training.
The number and complexity of assessments taught in HCUE training programs will determine their duration. With ongoing advancements in HCUE technology, there is a growing list of potential assessments to choose from. Although HCUE training programs ought to include assessments with proven clinical applications, there are no trials of HCUE‐directed care to inform such decisions. In their absence, therefore, we chose 6 assessments based on the following 3 criteria. First, our assessments were otherwise not reliably available from routine clinical data, such as the physical examination. Second, our assessments were straightforward: easy to learn and simple to perform. Here, we based our reasoning on an expectation that the value of HCUE lies not in highly complex, state‐of‐the‐art assessmentswhich are best left to echocardiographers equipped with SEbut in simple, routine assessments made with highly portable machines that grant noncardiologists newfound access to point‐of‐care data.34 Third, our assessments were clinically pertinent and, where appropriate, defined by cut‐points at levels of severity that often lead to changes in management. We suspect that setting high cut‐points has the salutary effects of making assessments easier to learn and more accurate, because distinguishing mild abnormalities is likely the most challenging aspect of echocardiographic interpretation.35 Whether or not our choices of assessments, and their cut‐points, are optimal has yet to be determined by future research designed to study how they affect patient outcomes. Given our hospitalists' performance in the present study, these assessments seem worthy of such future research.
Our study had several limitations. We studied physicians and patients from only 1 hospital; similar studies performed in different settings, particularly among patients with different proportions and manifestations of disease, may find different results. Nevertheless, our sampling method of prospectively enrolling consecutive patients strengthens our findings. Some echocardiographic measurement methods used by our hospitalists differed in subtle ways from echocardiography guideline recommendations.35 We chose our methods (Table 2) for 2 reasons. First, whenever possible, we chose methods of interpretation that coincided with our local cardiologists'. Second, we chose simplicity over precision. For example, the biplane method of disks, or modified Simpson's rule, is the preferred volumetric method of calculating LA size.35 This method requires tracing the contours of the LA in 2 planes and then dividing the LA volume into stacked oval disks for calculation. We chose instead to train our hospitalists in a simpler method based on 2 linear measurements. Any loss of precision, however, was balanced by a large gain in simplicity. Regardless, minor variations in LA size are not likely to affect hospitalists' bedside evaluations. Finally, we did not validate the results of our reference standard (SE) by documenting interobserver reliability. Yet, because SE is generally accurate for the 6 cardiac abnormalities under study, the effect of this bias should be small.
These limitations can be addressed best by controlled trials of HCUE‐directed care. These trials will determine the clinical impact of hospitalist‐performed HCUE and, in turn, inform our design of HCUE training programs. As the current study shows, training hospitalists to participate in such trials is feasible: like other groups of noncardiologists, hospitalists can accurately perform HCUE after a brief training program. Whether or not hospitalists should perform HCUE requires further study.
Acknowledgements
The authors thank Sonosite, Inc., Bothell, WA, for loaning us 2 MicroMaxx machines throughout the study period. They also thank the staff of the Internal Medicine Research Mentoring Program at Rush Medical College for their technical support and the staff of the Division of Neurology at Stroger Hospital for granting them access to a procedure room.
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- ,,, et al.ACC/AHA 2005 guideline update for the diagnosis and management of chronic heart failure in the adult: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines.Circulation.2005;112;154–235.
- ,,, et al.ACC/AHA 2006 guidelines for the management of patients with valvular heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines.Circulation.2006;114:e84–e231.
- ,,, et al.Left atrial size: physiologic determinants and clinical applications.J Am Coll Cardiol.2006;47:2357–2363.
- ,,,,.Prognostic implications of echocardiographically determined left ventricular mass in the Framingham Heart Study.N Engl J Med.1990;322:1561–1566.
- ,,,.Does this patient with a pericardial effusion have cardiac tamponade?JAMA.2007;297:1810–1818.
- .Acute cardiac tamponade.N Engl J Med.2003;349:685–690.
- ,,,,,.Evaluation of size and dynamics of the inferior vena cava as an index of right‐sided cardiac function.Am J Cardiol.1984;53:579–585.
- ,,.The influence of uninterpretability on the assessment of diagnostic tests.J Chronic Dis.1986;39:575–584.
- ,,.Relations between effectiveness of a diagnostic test, prevalence of the disease, and percentages of uninterpretable results. An example in the diagnosis of jaundice.Med Decis Making.1982;2:285–297.
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- ,,.Comparing the areas under two or more correlated receiver operating curves: a nonparametric approach.Biometrics.1988;44:837–845.
- ,,, et al.Systolic blood pressure at admission, clinical characteristics, and outcomes in patients hospitalized with acute heart failure.JAMA.2006;296:2217–2226.
- ,,, et al.Utility of history, physical examination, electrocardiogram, and chest radiograph for differentiating normal from decreased systolic function in patients with heart failure.Am J Med.2002;112:437–445.
- Joint Commission on Accreditation of Healthcare Organizations. Health Care Quality Data Download Website. Available at: http://www.healthcarequalitydata.org. Accessed December2008.
- ,,, et al.Towards complete and accurate reporting of studies of diagnostic accuracy: the STARD initiative.Clin Chem.2003;49:1–6.
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- ,,, et al.Recommendations for chamber quantification: a report from the American Society of Echocardiography's Guidelines and Standards Committee and the Chamber Quantification Writing Group, developed in conjunction with the European Association of Echocardiography, a branch of the European Society of Cardiology.J Am Soc Echocardiogr.2005;18:1440–1463.
Hand‐carried ultrasound echocardiography (HCUE) can help noncardiologists answer well‐defined questions at patients' bedsides in less than 10 minutes.1, 2 Indeed, intensivists3 and emergency department physicians4 already use HCUE to make rapid, point‐of‐care assessments. Since cardiovascular diagnoses are common among general medicine inpatients, HCUE may become an important skill for hospitalists to learn.5
However, uncertainty exists about the duration of HCUE training for hospitalists. In 2002, experts from the American Society of Echocardiography (ASE) published recommendations on training requirements for HCUE.6 With limited data on the safety or performance of HCUE training programs, which had just begun to emerge, the ASE borrowed from the proven training recommendations for standard echocardiography (SE). They recommended that all HCUE trainees, cardiologist and noncardiologist alike, complete level 1 SE training: 75 personally‐performed and 150 personally‐interpreted echocardiographic examinations. Since then, however, several HCUE training programs designed for noncardiologists have emerged.2, 5, 710 These alternative programs suggest that the ASE's recommended duration of training may be too long, particularly for focused HCUE that is limited to a few relatively simple assessments. It is important not to overshoot the requirements of HCUE training, because doing so may discourage groups of noncardiologists, like hospitalists, who may derive great benefits from HCUE.11
To address this uncertainty for hospitalists, we first developed a brief HCUE training program to assess 6 important cardiac abnormalities. We then studied the diagnostic accuracy of HCUE by hospitalists as a test of these 6 cardiac abnormalities assessed by SE.
Patients and Methods
Setting and Subjects
This prospective cohort study was performed at Stroger Hospital of Cook County, a 500‐bed public teaching hospital in Chicago, IL, from March through May of 2007. The cohort was adult inpatients who were referred for SE on weekdays from 3 distinct patient care units (Figure 1). We used 2 sampling modes to balance practical constraints (short‐stay unit [SSU] patients were more localized and, therefore, easier to study) with clinical diversity. We consecutively sampled patients from our SSU, where adults with provisional cardiovascular diagnoses are admitted if they might be eligible for discharge with in 3 days.12 But we used random number tables with a daily unique starting point to randomly sample patients from the general medical wards and the coronary care unit (CCU). Patients were excluded if repositioning them for HCUE was potentially harmful. The study was approved by our hospital's institutional review board, and we obtained written informed consent from all enrolled patients.
SE Protocol
As part of enrolled patients' routine clinical care, SE images were acquired and interpreted in the usual fashion in our hospital's echocardiography laboratory, which performs SE on over 7,000 patients per year. Echocardiographic technicians acquired images with a General Electric Vivid 7 cardiac ultrasound machine (General Electric, Milwaukee, WI) equipped with a GE M4S 1.8 to 3.4 MHz cardiac transducer (General Electric). Technicians followed the standard adult transthoracic echocardiography scanning protocol to acquire 40 to 100 images on every patient using all available echocardiographic modalities: 2‐dimensional, M‐mode, color Doppler, continuous‐wave Doppler, pulse‐wave Doppler, and tissue Doppler.13 Blinded to HCUE results, attending physician cardiologist echocardiographers then interpreted archived images using computer software (Centricity System; General Electric) to generate final reports that were entered into patients' medical records. This software ensured that final reports were standardized, because echocardiographers' final qualitative assessments were limited to short lists of standard options; for example, in reporting left atrium (LA) size, echocardiographers chose from only 5 standard options: normal, mildly dilated, moderately dilated, severely dilated, and not interpretable. Investigators, who were also blinded to HCUE results, later abstracted SE results from these standardized report forms in patients' medical records. All echocardiographers fulfilled ASE training guidelines to independently interpret SE: a minimum of 150 personally‐performed and 300 personally‐interpreted echocardiographic examinations (training level 2).14
HCUE Training
Based on the recommendations of our cardiologist investigator (B.M.), we developed a training program for 1 hospitalist to become an HCUE instructor. Our instructor trainee (C.C.) was board‐eligible in internal medicine but had no previous formal training in cardiology or echocardiography. We a priori established that her training would continue until our cardiologist investigator determined that she was ready to train other hospitalists; this determination occurred after 5 weeks. She learned image acquisition by performing focused SE on 30 patients under the direct supervision of an echocardiographic technician. She also performed focused HCUE on 65 inpatients without direct supervision but with ongoing access to consult the technician to review archived images and troubleshoot difficulties with acquisition. She learned image interpretation by reading relevant chapters from a SE textbook15 and by participating in daily didactic sessions in which attending cardiologist echocardiographers train cardiology fellows in SE interpretation.
This hospitalist then served as the HCUE instructor for 8 other attending physician hospitalists who were board‐certified internists with no previous formal training in cardiology or echocardiography. The training program was limited to acquisition and interpretation of 2‐dimensional grayscale and color Doppler images for the 6 cardiac assessments under study (Table 1). The instructor marshaled pairs of hospitalists through the 3 components of the training program, which lasted a total of 27 hours.
|
| Six cardiac assessments learned using 2‐dimensional gray scale and color Doppler imaging |
| Left ventricular systolic dysfunction |
| Mitral valve regurgitation |
| Left atrium enlargement |
| Left ventricular hypertrophy |
| Pericardial effusion |
| Inferior vena cava diameter |
| Lecture (2 hours)* |
| Basic principles of echocardiography |
| HCUE scanning protocol and helpful techniques to optimize image quality |
| Hands‐on training with instructor |
| Orientation to machine and demonstration of scanning protocol (1 hour) |
| Sessions 1 through 3: HCUE performed on 1 patient per hour (6 patients in 6 hours) |
| Sessions 4 through 10: HCUE performed on 2 patients per hour (28 patients in 14 hours) |
| Feedback sessions on image quality and interpretation with cardiologist |
| After hands‐on training session 3 (2 hours) |
| After hands‐on training session 10 (2 hours) |
First, hospitalists attended a 2‐hour lecture on the basic principles of HCUE. Slides from this lecture and additional images of normal and abnormal findings were provided to each hospitalist on a digital video disc. Second, each hospitalist underwent 20 hours of hands‐on training in 2‐hour sessions scheduled over 2 weeks. Willing inpatients from our hospital's emergency department were used as volunteers for these hand‐on training sessions. During these sessions the instructor provided practical suggestions to optimize image quality, such as transducer location and patient positioning. In the first 3 sessions, the minimum pace was 1 patient per hour; thereafter, the pace was increased to 1 patient per half‐hour. We chose 20 hours of hands‐on training and these minimum paces because they allowed each hospitalist to attain a cumulative experience of no less than 30 patientsan amount that heralds a flattening of the HCUE learning curve among medical trainees.9 Third, each pair of hospitalists received feedback from a cardiologist investigator (B.M.) who critiqued the quality and interpretation of images acquired by hospitalists during hands‐on training sessions. Since image quality varies by patient,16 hospitalists' images were compared side‐by‐side to images recorded by the instructor on the same patients. The cardiologist also critiqued hospitalists' interpretations of both their own images and additional sets of archived images from patients with abnormal findings.
HCUE Protocol
After completing the training program and blinded to the results of SE, the 8 hospitalists performed HCUE on enrolled patients within hours of SE. We limited the time interval between tests to minimize the effect that changes in physiologic variables, such as blood pressure and intravascular volume, have on the reliability of serial echocardiographic measurements.16 Hospitalists performed HCUE with a MicroMaxx 3.4 hand‐carried ultrasound machine equipped with a cardiology software package and a 1 to 5 MHz P17 cardiac transducer (Sonosite, Inc., Bothell, WA); simultaneous electrocardiographic recording, though available, was not used. While patients laid on their own standard hospital beds or on a standard hospital gurney in a room adjacent to the SE waiting room, hospitalists positioned them without assistance from nursing staff and recorded 7 best‐quality images per patient. Patients were first positioned in a partial (3045 degrees) left lateral decubitus position to record 4 grayscale images of the short‐axis and long‐axis parasternal and 2‐chamber and 4‐chamber apical views; 2 color Doppler images of the mitral inflow were also recorded from the long‐axis parasternal and the 4‐chamber apical views. Patients were then positioned supine to record 1 grayscale image of the inferior vena cava (IVC) from the transhepatic view. Hospitalists did not perform a history or physical exam on enrolled patients, nor did they review patients' medical records.
Immediately following the HCUE, hospitalists replayed the recorded images as often as needed and entered final interpretations on data collection forms. Linear measurements were made manually with a caliper held directly to the hand‐carried ultrasound monitor. These measurements were then translated into qualitative assessments based on standard values used by our hospital's echocardiographers (Table 2).17 When a hospitalist could not confidently assess a cardiac abnormality, the final HCUE assessment was recorded as indeterminate. Hospitalists also recorded the time to perform each HCUE, which included the time to record 7 best‐quality images, to interpret the findings, and to fill out the data collection form.
| Hand‐Carried Ultrasound Echocardiography Results | |||||
|---|---|---|---|---|---|
| Cardiac Abnormality by Standard Echocardiography | Hand‐Carried Ultrasound Echocardiography Operator's Method of Assessment | Positive | Negative | ||
| |||||
| Left ventricle systolic dysfunction, mild or greater | Grade degree of abnormal wall movement and thickening during systole | Severe | Mild or moderate | Normal | Vigorous |
| Mitral valve regurgitation, severe | Classify regurgitant jet as central or eccentric, then measure as percentage of left atrium area | ||||
| Central jet | 20% | <20% | |||
| Eccentric jet | 20% | indeterminate 20% | |||
| Left atrium enlargement, moderate or severe | Measure left atrium in 3 dimensions at end diastole, then use the most abnormal dimension | Extreme | Borderline | ||
| Anteroposterior or mediolateral (cm) | 5.1 | 4.55.0 | 4.4 | ||
| Superior‐inferior (cm) | 7.1 | 6.17.0 | 6.0 | ||
| Left ventricle hypertrophy, moderate or severe | Measure thickest dimension of posterior or septal wall at end diastole | Extreme: 1.4 cm | Borderline: 1.21.3 cm | 1.1 cm | |
| Pericardial effusion, medium or large | Measure largest dimension in any view at end diastole | 1 cm | <1 cm | ||
| Inferior vena cava dilatation | Measure largest respirophasic diameter within 2 cm of right atrium | 2.1 cm | Normal: 1 to 2 cm | Contracted: 0.9 cm | |
Data Analysis
We based our sample size calculations on earlier reports of HCUE by noncardiologist trainees for assessment of left ventricular (LV) systolic function.7, 10 From these reports, we estimated a negative likelihood ratio of 0.3. In addition, we expected about a quarter of our patients to have LV systolic dysfunction (B.M., personal communication). Therefore, to achieve 95% confidence intervals (CIs) around the point estimate of a negative likelihood ratio that excluded 0.50, our upper bound for a clinically meaningful result, we needed a sample size of approximately 300 patients.18
We defined threshold levels of ordinal severity for the 6 cardiac abnormalities under study based on their clinical pertinence to hospitalists (Table 2). Here, we reasoned that abnormalities at or above these levels would likely lead to important changes in hospitalists' management of inpatients; abnormalities below these levels rarely represent cardiac disease that is worthy of an immediate change in management. Since even mild degrees of LV dysfunction have important diagnostic and therapeutic implications for most general medicine inpatients, particularly those presenting with heart failure,19 we set our threshold for LV dysfunction at mild or greater. In contrast, since neither mild nor moderate mitral regurgitation (MR) has immediate implications for medical or surgical therapy even if symptoms or LV dysfunction are present,20 we set our threshold for MR at severe. Similarly, though mild LA enlargement21 and mild LV hypertrophy22 have clear prognostic implications for patients' chronic medical conditions, we reasoned that only moderate or severe versions likely reflect underlying abnormalities that affect hospitalists' point‐of‐care decision‐making. Since cardiac tamponade is rarely both subclinical23 and due to a small pericardial effusion,24 we set our threshold for pericardial effusion size at moderate or large. Finally, we set our threshold IVC diameter, a marker of central venous volume status,25 at dilated, because volume overload is an important consideration in hospitalized cardiac patients.
Using these thresholds, investigators dichotomized echocardiographers' SE readings as normal or abnormal for each of the 6 cardiac abnormalities under study to serve as the reference standards. Hospitalists' HCUE results were then compared to the reference standards in 2 different ways. We first analyzed HCUE results as dichotomous values to calculate conventional sensitivity, specificity, and positive and negative likelihood ratios. Here we considered indeterminate HCUE results positive in a clinically conservative tradeoff that neither ignores indeterminate results nor risks falsely classifying them as negative.26 We then analyzed hospitalists' HCUE results as ordinal values for receiver operating characteristic (ROC) curve analysis. Here we considered an indeterminate result as 1 possible test result.27
To examine interobserver variability of HCUE, we first chose from the 6 possible assessments only those with a mean number of abnormal patients per hospitalist greater than 5. We reasoned that variability among assessments with lower prevalence would be predictably wide and inconclusive. We then expressed variability as standard deviations (SDs) around mean sensitivity and specificity for the 8 hospitalists.
The CIs for likelihood ratios were constructed using the likelihood‐based approach to binomial proportions of Koopman.28 The areas under ROC curves were computed using the trapezoidal rule, and the CIs for these areas were constructed using the algorithm described by DeLong et al.29 All analyses were conducted with Stata Statistical Software, Release 10 (StataCorp, College Station, TX).
Results
During the 3 month study period, 654 patients were referred for SE from the 3 participating patient care units (Figure 1). Among these, 65 patients were ineligible because their SE was performed on the weekend and 178 other patients were not randomized from the general medical wards and CCU. From the remaining eligible patients, 322 underwent HCUE and 314 (98% of 322) underwent both SE and HCUE. Individual SE assessments were not interpretable (and therefore excluded) due to poor image quality for LA enlargement in 1 patient and IVC dilatation in 30 patients. Eighty‐three percent of patients who underwent SE (260/314) were referred to assess LV function (Table 3). The prevalence of the 6 clinically pertinent cardiac abnormalities under study ranged from 1% for moderate or large pericardial effusion to 25% for LV systolic dysfunction. Overall, 40% of patients had at least 1 out of 6 cardiac abnormalities.
| Characteristic | |
|---|---|
| |
| Age, year SD (25th to 75th percentiles) | 56 13 (48 to 64) |
| Women | 146 (47) |
| Chronic obstructive pulmonary disease | 47 (15) |
| Body mass index | |
| 24.9 or less: underweight or normal | 74 (24) |
| 25 to 29.9: overweight | 94 (30) |
| 30 to 34.9: mild obesity | 75 (24) |
| 35 or greater: moderate or severe obesity | 71 (23) |
| Patient care unit | |
| Short‐stay unit | 175 (56) |
| General medical wards | 89 (28) |
| Cardiac care unit | 50 (16) |
| Indication for standard echocardiography* | |
| Left ventricular function | 260 (83) |
| Valvular function | 56 (18) |
| Wall motion abnormality | 29 (9) |
| Valvular vegetations | 22 (7) |
| Any structural heart disease | 20 (6) |
| Right ventricular function | 18 (6) |
| Other | 38 (12) |
| Standard echocardiography findings | |
| Left ventricular systolic dysfunction mild | 80 (25) |
| Inferior vena cava dilated | 45 (14) |
| Left ventricular wall thickness moderate | 33 (11) |
| Left atrium enlargement moderate | 19 (6) |
| Mitral valve regurgitation severe | 11 (4) |
| Pericardial effusion moderate | 3 (1) |
| At least 1 of the above findings | 127 (40) |
| Time difference between HCUE and standard echocardiogram, median hours (25th to 75th percentiles) | 2.8 (1.4 to 5.1) |
| Time to complete HCUE, median minutes (25th to 75th percentiles) | 28 (20 to 35) |
Each hospitalist performed a similar total number of HCUE examinations (range, 3447). The median time difference between performance of SE and HCUE was 2.8 hours (25th75th percentiles, 1.45.1). Despite the high prevalence of chronic obstructive pulmonary disease and obesity, hospitalists considered HCUE assessments indeterminate in only 2% to 6% of the 6 assessments made for each patient (Table 4). Among the 38 patients (12% of 322) with any indeterminate HCUE assessment, 24 patients had only 1 out of 6 possible. Hospitalists completed HCUE in a median time of 28 minutes (25th‐75th percentiles, 2035), which included the time to record 7 best‐quality moving images and to fill out the research data collection form.
| n (%)* | |
|---|---|
| |
| Number of indeterminate findings per patient | |
| 0 | 284 (88) |
| 1 | 24 (7) |
| 2 | 4 (1) |
| 3 or more | 10 (3) |
| Indeterminate findings by cardiac assessment | |
| Mitral valve regurgitation | 18 (6) |
| Inferior vena cava diameter | 16 (5) |
| Left ventricular hypertrophy | 15 (5) |
| Pericardial effusion | 9 (3) |
| Left atrium size | 5 (2) |
| Left ventricle systolic function | 5 (2) |
When HCUE results were analyzed as dichotomous values, positive likelihood ratios ranged from 2.5 to 21, and negative likelihood ratios ranged from 0 to 0.4 (Table 5). Positive and negative likelihood ratios were both sufficiency high and low to respectively increase and decrease by 5‐fold the prior odds of 3 out of 6 cardiac abnormalities: LV systolic dysfunction, moderate or severe MR regurgitation, and moderate or large pericardial effusion. Considering HCUE results as ordinal values for ROC analysis yielded additional diagnostic information (Figure 2). For example, the likelihood ratio of 1.0 (95% CI, 0.42.0) for borderline positive moderate or severe LA enlargement increased to 29 (range, 1362) for extreme positive results. Areas under the ROC curves were 0.9 for 4 out of 6 cardiac abnormalities.
| Clinically Pertinent Cardiac Abnormality by Standard Echocardiography | Prevalence n/total n | Sensitivity* % (95% CI) | Specificity* % (95% CI) | LRpositive*, (95% CI) | LRnegative*, (95% CI) |
|---|---|---|---|---|---|
| |||||
| Left ventricular systolic dysfunction | 80/314 | 85 (7592) | 88 (8392) | 6.9 (4.99.8) | 0.2 (0.10.3) |
| Mitral valve regurgitation, severe | 11/314 | 100 (72100) | 83 (7987) | 5.9 (3.97.4) | 0 (00.3) |
| Left atrium enlargement, moderate or severe | 19/313 | 90 (6799) | 74 (6879) | 3.4 (2.54.3) | 0.1 (0.040.4) |
| Left ventricular hypertrophy, moderate or severe | 33/314 | 70 (5184) | 73 (6778) | 2.5 (1.83.3) | 0.4 (0.20.7) |
| Pericardial effusion, moderate or large | 3/314 | 100 (29100) | 95 (9297) | 21 (6.731) | 0 (00.6) |
| Inferior vena cava, dilated | 45/284 | 56 (4070) | 86 (8190) | 4.0 (2.66.0) | 0.5 (0.40.7) |
LV systolic dysfunction and IVC dilatation were both prevalent enough to meet our criterion to examine interobserver variability; the mean number of abnormal patients per hospitalist was 10 patients for LV systolic dysfunction and 6 patients for IVC dilatation. For LV systolic dysfunction, SDs around mean sensitivity (84%) and specificity (87%) were 12% and 6%, respectively. For IVC dilatation, SDs around mean sensitivity (58%) and specificity (86%) were 24% and 7%, respectively.
Discussion
We found that, after a 27‐hour training program, hospitalists performed HCUE with moderate to excellent diagnostic accuracy for 6 important cardiac abnormalities. For example, hospitalists' assessments of LV systolic function yielded positive and negative likelihood ratios of 6.9 (95% CI, 4.99.8) and 0.2 (95% CI, 0.10.3), respectively. At the bedsides of patients with acute heart failure, therefore, hospitalists could use HCUE to lower or raise the 50:50 chance of LV systolic dysfunction30 to 15% or 85%, respectively. Whether or not these posttest likelihoods are extreme enough to cross important thresholds will depend on the clinical context. Yet these findings demonstrate how HCUE has the potential to provide hospitalists with valuable point‐of‐care data that are otherwise unavailableeither because routine clinical assessments are unreliable31 or because echocardiographic services are not immediately accessible.1
In fact, recent data from the Joint Commission on Accreditation of Healthcare Organizations shows how inaccessible SE may be. Approximately one‐quarter of hospitals in the United States send home about 10% of patients with acute heart failure without echocardiographic assessment of LV systolic function before, during, or immediately after hospitalization.32 In doing so, these hospitals leave unmet the 2002 National Quality Improvement Goal of universal assessment of LV systolic function for all heart failure patients. Hospitalists could close this quality gap with routine, 10‐minute HCUE assessments in all patients admitted with acute heart failure. (Our research HCUE protocol required a median time of 28 minutes, but this included time to assess 5 other cardiac abnormalities and collect data for research purposes). Until the clinical consequences of introducing hospitalist‐performed HCUE are studied, potential benefits like this are tentative. But our findings suggest that training hospitalists to accurately perform HCUE can be successfully accomplished in just 27 hours.
Other studies of HCUE training programs for noncardiologists have also challenged the opinion that learning to perform HCUE requires more than 100 hours of training.2, 711 Yet only 1 prior study has examined an HCUE training program for hospitalists.5 In this study by Martin et al.,5 hospitalists completed 5 supervised HCUE examinations and 6 hours of interpretation training before investigators scored their image acquisition and interpretation skills from 30 unsupervised HCUE examinations. To estimate their final skill levels at the completion of all 35 examinations by accounting for an initially steep learning curve, investigators then adjusted these scores with regression models. Despite these upward adjustments, hospitalists' image acquisition and interpretation scores were low in comparison to echocardiographic technicians and cardiology fellows. Besides these adjusted measurements of hospitalists' skills, however, Martin et al.5 unfortunately did not also report standard measures of diagnostic accuracy, like those proposed by the Standards for Reporting of Diagnostic Accuracy (STARD) initiative.33 Therefore, direct comparisons to the present study are difficult. Nevertheless, their findings suggest that a training program limited to 5 supervised HCUE examinations may be inadequate for hospitalists. In fact, the same group's earlier study of medical trainees suggested a minimum of 30 supervised HCUE examinations.9 We chose to design our hospitalist training program based on this minimum, though they surprisingly did not.5 As others continue to refine the components of hospitalist HCUE training programs, such as the optimal number of supervised examinations, our program could serve as a reasonable comparative example: more rigorous than the program designed by Martin et al.5 but more feasible than ASE level 1 training.
The number and complexity of assessments taught in HCUE training programs will determine their duration. With ongoing advancements in HCUE technology, there is a growing list of potential assessments to choose from. Although HCUE training programs ought to include assessments with proven clinical applications, there are no trials of HCUE‐directed care to inform such decisions. In their absence, therefore, we chose 6 assessments based on the following 3 criteria. First, our assessments were otherwise not reliably available from routine clinical data, such as the physical examination. Second, our assessments were straightforward: easy to learn and simple to perform. Here, we based our reasoning on an expectation that the value of HCUE lies not in highly complex, state‐of‐the‐art assessmentswhich are best left to echocardiographers equipped with SEbut in simple, routine assessments made with highly portable machines that grant noncardiologists newfound access to point‐of‐care data.34 Third, our assessments were clinically pertinent and, where appropriate, defined by cut‐points at levels of severity that often lead to changes in management. We suspect that setting high cut‐points has the salutary effects of making assessments easier to learn and more accurate, because distinguishing mild abnormalities is likely the most challenging aspect of echocardiographic interpretation.35 Whether or not our choices of assessments, and their cut‐points, are optimal has yet to be determined by future research designed to study how they affect patient outcomes. Given our hospitalists' performance in the present study, these assessments seem worthy of such future research.
Our study had several limitations. We studied physicians and patients from only 1 hospital; similar studies performed in different settings, particularly among patients with different proportions and manifestations of disease, may find different results. Nevertheless, our sampling method of prospectively enrolling consecutive patients strengthens our findings. Some echocardiographic measurement methods used by our hospitalists differed in subtle ways from echocardiography guideline recommendations.35 We chose our methods (Table 2) for 2 reasons. First, whenever possible, we chose methods of interpretation that coincided with our local cardiologists'. Second, we chose simplicity over precision. For example, the biplane method of disks, or modified Simpson's rule, is the preferred volumetric method of calculating LA size.35 This method requires tracing the contours of the LA in 2 planes and then dividing the LA volume into stacked oval disks for calculation. We chose instead to train our hospitalists in a simpler method based on 2 linear measurements. Any loss of precision, however, was balanced by a large gain in simplicity. Regardless, minor variations in LA size are not likely to affect hospitalists' bedside evaluations. Finally, we did not validate the results of our reference standard (SE) by documenting interobserver reliability. Yet, because SE is generally accurate for the 6 cardiac abnormalities under study, the effect of this bias should be small.
These limitations can be addressed best by controlled trials of HCUE‐directed care. These trials will determine the clinical impact of hospitalist‐performed HCUE and, in turn, inform our design of HCUE training programs. As the current study shows, training hospitalists to participate in such trials is feasible: like other groups of noncardiologists, hospitalists can accurately perform HCUE after a brief training program. Whether or not hospitalists should perform HCUE requires further study.
Acknowledgements
The authors thank Sonosite, Inc., Bothell, WA, for loaning us 2 MicroMaxx machines throughout the study period. They also thank the staff of the Internal Medicine Research Mentoring Program at Rush Medical College for their technical support and the staff of the Division of Neurology at Stroger Hospital for granting them access to a procedure room.
Hand‐carried ultrasound echocardiography (HCUE) can help noncardiologists answer well‐defined questions at patients' bedsides in less than 10 minutes.1, 2 Indeed, intensivists3 and emergency department physicians4 already use HCUE to make rapid, point‐of‐care assessments. Since cardiovascular diagnoses are common among general medicine inpatients, HCUE may become an important skill for hospitalists to learn.5
However, uncertainty exists about the duration of HCUE training for hospitalists. In 2002, experts from the American Society of Echocardiography (ASE) published recommendations on training requirements for HCUE.6 With limited data on the safety or performance of HCUE training programs, which had just begun to emerge, the ASE borrowed from the proven training recommendations for standard echocardiography (SE). They recommended that all HCUE trainees, cardiologist and noncardiologist alike, complete level 1 SE training: 75 personally‐performed and 150 personally‐interpreted echocardiographic examinations. Since then, however, several HCUE training programs designed for noncardiologists have emerged.2, 5, 710 These alternative programs suggest that the ASE's recommended duration of training may be too long, particularly for focused HCUE that is limited to a few relatively simple assessments. It is important not to overshoot the requirements of HCUE training, because doing so may discourage groups of noncardiologists, like hospitalists, who may derive great benefits from HCUE.11
To address this uncertainty for hospitalists, we first developed a brief HCUE training program to assess 6 important cardiac abnormalities. We then studied the diagnostic accuracy of HCUE by hospitalists as a test of these 6 cardiac abnormalities assessed by SE.
Patients and Methods
Setting and Subjects
This prospective cohort study was performed at Stroger Hospital of Cook County, a 500‐bed public teaching hospital in Chicago, IL, from March through May of 2007. The cohort was adult inpatients who were referred for SE on weekdays from 3 distinct patient care units (Figure 1). We used 2 sampling modes to balance practical constraints (short‐stay unit [SSU] patients were more localized and, therefore, easier to study) with clinical diversity. We consecutively sampled patients from our SSU, where adults with provisional cardiovascular diagnoses are admitted if they might be eligible for discharge with in 3 days.12 But we used random number tables with a daily unique starting point to randomly sample patients from the general medical wards and the coronary care unit (CCU). Patients were excluded if repositioning them for HCUE was potentially harmful. The study was approved by our hospital's institutional review board, and we obtained written informed consent from all enrolled patients.
SE Protocol
As part of enrolled patients' routine clinical care, SE images were acquired and interpreted in the usual fashion in our hospital's echocardiography laboratory, which performs SE on over 7,000 patients per year. Echocardiographic technicians acquired images with a General Electric Vivid 7 cardiac ultrasound machine (General Electric, Milwaukee, WI) equipped with a GE M4S 1.8 to 3.4 MHz cardiac transducer (General Electric). Technicians followed the standard adult transthoracic echocardiography scanning protocol to acquire 40 to 100 images on every patient using all available echocardiographic modalities: 2‐dimensional, M‐mode, color Doppler, continuous‐wave Doppler, pulse‐wave Doppler, and tissue Doppler.13 Blinded to HCUE results, attending physician cardiologist echocardiographers then interpreted archived images using computer software (Centricity System; General Electric) to generate final reports that were entered into patients' medical records. This software ensured that final reports were standardized, because echocardiographers' final qualitative assessments were limited to short lists of standard options; for example, in reporting left atrium (LA) size, echocardiographers chose from only 5 standard options: normal, mildly dilated, moderately dilated, severely dilated, and not interpretable. Investigators, who were also blinded to HCUE results, later abstracted SE results from these standardized report forms in patients' medical records. All echocardiographers fulfilled ASE training guidelines to independently interpret SE: a minimum of 150 personally‐performed and 300 personally‐interpreted echocardiographic examinations (training level 2).14
HCUE Training
Based on the recommendations of our cardiologist investigator (B.M.), we developed a training program for 1 hospitalist to become an HCUE instructor. Our instructor trainee (C.C.) was board‐eligible in internal medicine but had no previous formal training in cardiology or echocardiography. We a priori established that her training would continue until our cardiologist investigator determined that she was ready to train other hospitalists; this determination occurred after 5 weeks. She learned image acquisition by performing focused SE on 30 patients under the direct supervision of an echocardiographic technician. She also performed focused HCUE on 65 inpatients without direct supervision but with ongoing access to consult the technician to review archived images and troubleshoot difficulties with acquisition. She learned image interpretation by reading relevant chapters from a SE textbook15 and by participating in daily didactic sessions in which attending cardiologist echocardiographers train cardiology fellows in SE interpretation.
This hospitalist then served as the HCUE instructor for 8 other attending physician hospitalists who were board‐certified internists with no previous formal training in cardiology or echocardiography. The training program was limited to acquisition and interpretation of 2‐dimensional grayscale and color Doppler images for the 6 cardiac assessments under study (Table 1). The instructor marshaled pairs of hospitalists through the 3 components of the training program, which lasted a total of 27 hours.
|
| Six cardiac assessments learned using 2‐dimensional gray scale and color Doppler imaging |
| Left ventricular systolic dysfunction |
| Mitral valve regurgitation |
| Left atrium enlargement |
| Left ventricular hypertrophy |
| Pericardial effusion |
| Inferior vena cava diameter |
| Lecture (2 hours)* |
| Basic principles of echocardiography |
| HCUE scanning protocol and helpful techniques to optimize image quality |
| Hands‐on training with instructor |
| Orientation to machine and demonstration of scanning protocol (1 hour) |
| Sessions 1 through 3: HCUE performed on 1 patient per hour (6 patients in 6 hours) |
| Sessions 4 through 10: HCUE performed on 2 patients per hour (28 patients in 14 hours) |
| Feedback sessions on image quality and interpretation with cardiologist |
| After hands‐on training session 3 (2 hours) |
| After hands‐on training session 10 (2 hours) |
First, hospitalists attended a 2‐hour lecture on the basic principles of HCUE. Slides from this lecture and additional images of normal and abnormal findings were provided to each hospitalist on a digital video disc. Second, each hospitalist underwent 20 hours of hands‐on training in 2‐hour sessions scheduled over 2 weeks. Willing inpatients from our hospital's emergency department were used as volunteers for these hand‐on training sessions. During these sessions the instructor provided practical suggestions to optimize image quality, such as transducer location and patient positioning. In the first 3 sessions, the minimum pace was 1 patient per hour; thereafter, the pace was increased to 1 patient per half‐hour. We chose 20 hours of hands‐on training and these minimum paces because they allowed each hospitalist to attain a cumulative experience of no less than 30 patientsan amount that heralds a flattening of the HCUE learning curve among medical trainees.9 Third, each pair of hospitalists received feedback from a cardiologist investigator (B.M.) who critiqued the quality and interpretation of images acquired by hospitalists during hands‐on training sessions. Since image quality varies by patient,16 hospitalists' images were compared side‐by‐side to images recorded by the instructor on the same patients. The cardiologist also critiqued hospitalists' interpretations of both their own images and additional sets of archived images from patients with abnormal findings.
HCUE Protocol
After completing the training program and blinded to the results of SE, the 8 hospitalists performed HCUE on enrolled patients within hours of SE. We limited the time interval between tests to minimize the effect that changes in physiologic variables, such as blood pressure and intravascular volume, have on the reliability of serial echocardiographic measurements.16 Hospitalists performed HCUE with a MicroMaxx 3.4 hand‐carried ultrasound machine equipped with a cardiology software package and a 1 to 5 MHz P17 cardiac transducer (Sonosite, Inc., Bothell, WA); simultaneous electrocardiographic recording, though available, was not used. While patients laid on their own standard hospital beds or on a standard hospital gurney in a room adjacent to the SE waiting room, hospitalists positioned them without assistance from nursing staff and recorded 7 best‐quality images per patient. Patients were first positioned in a partial (3045 degrees) left lateral decubitus position to record 4 grayscale images of the short‐axis and long‐axis parasternal and 2‐chamber and 4‐chamber apical views; 2 color Doppler images of the mitral inflow were also recorded from the long‐axis parasternal and the 4‐chamber apical views. Patients were then positioned supine to record 1 grayscale image of the inferior vena cava (IVC) from the transhepatic view. Hospitalists did not perform a history or physical exam on enrolled patients, nor did they review patients' medical records.
Immediately following the HCUE, hospitalists replayed the recorded images as often as needed and entered final interpretations on data collection forms. Linear measurements were made manually with a caliper held directly to the hand‐carried ultrasound monitor. These measurements were then translated into qualitative assessments based on standard values used by our hospital's echocardiographers (Table 2).17 When a hospitalist could not confidently assess a cardiac abnormality, the final HCUE assessment was recorded as indeterminate. Hospitalists also recorded the time to perform each HCUE, which included the time to record 7 best‐quality images, to interpret the findings, and to fill out the data collection form.
| Hand‐Carried Ultrasound Echocardiography Results | |||||
|---|---|---|---|---|---|
| Cardiac Abnormality by Standard Echocardiography | Hand‐Carried Ultrasound Echocardiography Operator's Method of Assessment | Positive | Negative | ||
| |||||
| Left ventricle systolic dysfunction, mild or greater | Grade degree of abnormal wall movement and thickening during systole | Severe | Mild or moderate | Normal | Vigorous |
| Mitral valve regurgitation, severe | Classify regurgitant jet as central or eccentric, then measure as percentage of left atrium area | ||||
| Central jet | 20% | <20% | |||
| Eccentric jet | 20% | indeterminate 20% | |||
| Left atrium enlargement, moderate or severe | Measure left atrium in 3 dimensions at end diastole, then use the most abnormal dimension | Extreme | Borderline | ||
| Anteroposterior or mediolateral (cm) | 5.1 | 4.55.0 | 4.4 | ||
| Superior‐inferior (cm) | 7.1 | 6.17.0 | 6.0 | ||
| Left ventricle hypertrophy, moderate or severe | Measure thickest dimension of posterior or septal wall at end diastole | Extreme: 1.4 cm | Borderline: 1.21.3 cm | 1.1 cm | |
| Pericardial effusion, medium or large | Measure largest dimension in any view at end diastole | 1 cm | <1 cm | ||
| Inferior vena cava dilatation | Measure largest respirophasic diameter within 2 cm of right atrium | 2.1 cm | Normal: 1 to 2 cm | Contracted: 0.9 cm | |
Data Analysis
We based our sample size calculations on earlier reports of HCUE by noncardiologist trainees for assessment of left ventricular (LV) systolic function.7, 10 From these reports, we estimated a negative likelihood ratio of 0.3. In addition, we expected about a quarter of our patients to have LV systolic dysfunction (B.M., personal communication). Therefore, to achieve 95% confidence intervals (CIs) around the point estimate of a negative likelihood ratio that excluded 0.50, our upper bound for a clinically meaningful result, we needed a sample size of approximately 300 patients.18
We defined threshold levels of ordinal severity for the 6 cardiac abnormalities under study based on their clinical pertinence to hospitalists (Table 2). Here, we reasoned that abnormalities at or above these levels would likely lead to important changes in hospitalists' management of inpatients; abnormalities below these levels rarely represent cardiac disease that is worthy of an immediate change in management. Since even mild degrees of LV dysfunction have important diagnostic and therapeutic implications for most general medicine inpatients, particularly those presenting with heart failure,19 we set our threshold for LV dysfunction at mild or greater. In contrast, since neither mild nor moderate mitral regurgitation (MR) has immediate implications for medical or surgical therapy even if symptoms or LV dysfunction are present,20 we set our threshold for MR at severe. Similarly, though mild LA enlargement21 and mild LV hypertrophy22 have clear prognostic implications for patients' chronic medical conditions, we reasoned that only moderate or severe versions likely reflect underlying abnormalities that affect hospitalists' point‐of‐care decision‐making. Since cardiac tamponade is rarely both subclinical23 and due to a small pericardial effusion,24 we set our threshold for pericardial effusion size at moderate or large. Finally, we set our threshold IVC diameter, a marker of central venous volume status,25 at dilated, because volume overload is an important consideration in hospitalized cardiac patients.
Using these thresholds, investigators dichotomized echocardiographers' SE readings as normal or abnormal for each of the 6 cardiac abnormalities under study to serve as the reference standards. Hospitalists' HCUE results were then compared to the reference standards in 2 different ways. We first analyzed HCUE results as dichotomous values to calculate conventional sensitivity, specificity, and positive and negative likelihood ratios. Here we considered indeterminate HCUE results positive in a clinically conservative tradeoff that neither ignores indeterminate results nor risks falsely classifying them as negative.26 We then analyzed hospitalists' HCUE results as ordinal values for receiver operating characteristic (ROC) curve analysis. Here we considered an indeterminate result as 1 possible test result.27
To examine interobserver variability of HCUE, we first chose from the 6 possible assessments only those with a mean number of abnormal patients per hospitalist greater than 5. We reasoned that variability among assessments with lower prevalence would be predictably wide and inconclusive. We then expressed variability as standard deviations (SDs) around mean sensitivity and specificity for the 8 hospitalists.
The CIs for likelihood ratios were constructed using the likelihood‐based approach to binomial proportions of Koopman.28 The areas under ROC curves were computed using the trapezoidal rule, and the CIs for these areas were constructed using the algorithm described by DeLong et al.29 All analyses were conducted with Stata Statistical Software, Release 10 (StataCorp, College Station, TX).
Results
During the 3 month study period, 654 patients were referred for SE from the 3 participating patient care units (Figure 1). Among these, 65 patients were ineligible because their SE was performed on the weekend and 178 other patients were not randomized from the general medical wards and CCU. From the remaining eligible patients, 322 underwent HCUE and 314 (98% of 322) underwent both SE and HCUE. Individual SE assessments were not interpretable (and therefore excluded) due to poor image quality for LA enlargement in 1 patient and IVC dilatation in 30 patients. Eighty‐three percent of patients who underwent SE (260/314) were referred to assess LV function (Table 3). The prevalence of the 6 clinically pertinent cardiac abnormalities under study ranged from 1% for moderate or large pericardial effusion to 25% for LV systolic dysfunction. Overall, 40% of patients had at least 1 out of 6 cardiac abnormalities.
| Characteristic | |
|---|---|
| |
| Age, year SD (25th to 75th percentiles) | 56 13 (48 to 64) |
| Women | 146 (47) |
| Chronic obstructive pulmonary disease | 47 (15) |
| Body mass index | |
| 24.9 or less: underweight or normal | 74 (24) |
| 25 to 29.9: overweight | 94 (30) |
| 30 to 34.9: mild obesity | 75 (24) |
| 35 or greater: moderate or severe obesity | 71 (23) |
| Patient care unit | |
| Short‐stay unit | 175 (56) |
| General medical wards | 89 (28) |
| Cardiac care unit | 50 (16) |
| Indication for standard echocardiography* | |
| Left ventricular function | 260 (83) |
| Valvular function | 56 (18) |
| Wall motion abnormality | 29 (9) |
| Valvular vegetations | 22 (7) |
| Any structural heart disease | 20 (6) |
| Right ventricular function | 18 (6) |
| Other | 38 (12) |
| Standard echocardiography findings | |
| Left ventricular systolic dysfunction mild | 80 (25) |
| Inferior vena cava dilated | 45 (14) |
| Left ventricular wall thickness moderate | 33 (11) |
| Left atrium enlargement moderate | 19 (6) |
| Mitral valve regurgitation severe | 11 (4) |
| Pericardial effusion moderate | 3 (1) |
| At least 1 of the above findings | 127 (40) |
| Time difference between HCUE and standard echocardiogram, median hours (25th to 75th percentiles) | 2.8 (1.4 to 5.1) |
| Time to complete HCUE, median minutes (25th to 75th percentiles) | 28 (20 to 35) |
Each hospitalist performed a similar total number of HCUE examinations (range, 3447). The median time difference between performance of SE and HCUE was 2.8 hours (25th75th percentiles, 1.45.1). Despite the high prevalence of chronic obstructive pulmonary disease and obesity, hospitalists considered HCUE assessments indeterminate in only 2% to 6% of the 6 assessments made for each patient (Table 4). Among the 38 patients (12% of 322) with any indeterminate HCUE assessment, 24 patients had only 1 out of 6 possible. Hospitalists completed HCUE in a median time of 28 minutes (25th‐75th percentiles, 2035), which included the time to record 7 best‐quality moving images and to fill out the research data collection form.
| n (%)* | |
|---|---|
| |
| Number of indeterminate findings per patient | |
| 0 | 284 (88) |
| 1 | 24 (7) |
| 2 | 4 (1) |
| 3 or more | 10 (3) |
| Indeterminate findings by cardiac assessment | |
| Mitral valve regurgitation | 18 (6) |
| Inferior vena cava diameter | 16 (5) |
| Left ventricular hypertrophy | 15 (5) |
| Pericardial effusion | 9 (3) |
| Left atrium size | 5 (2) |
| Left ventricle systolic function | 5 (2) |
When HCUE results were analyzed as dichotomous values, positive likelihood ratios ranged from 2.5 to 21, and negative likelihood ratios ranged from 0 to 0.4 (Table 5). Positive and negative likelihood ratios were both sufficiency high and low to respectively increase and decrease by 5‐fold the prior odds of 3 out of 6 cardiac abnormalities: LV systolic dysfunction, moderate or severe MR regurgitation, and moderate or large pericardial effusion. Considering HCUE results as ordinal values for ROC analysis yielded additional diagnostic information (Figure 2). For example, the likelihood ratio of 1.0 (95% CI, 0.42.0) for borderline positive moderate or severe LA enlargement increased to 29 (range, 1362) for extreme positive results. Areas under the ROC curves were 0.9 for 4 out of 6 cardiac abnormalities.
| Clinically Pertinent Cardiac Abnormality by Standard Echocardiography | Prevalence n/total n | Sensitivity* % (95% CI) | Specificity* % (95% CI) | LRpositive*, (95% CI) | LRnegative*, (95% CI) |
|---|---|---|---|---|---|
| |||||
| Left ventricular systolic dysfunction | 80/314 | 85 (7592) | 88 (8392) | 6.9 (4.99.8) | 0.2 (0.10.3) |
| Mitral valve regurgitation, severe | 11/314 | 100 (72100) | 83 (7987) | 5.9 (3.97.4) | 0 (00.3) |
| Left atrium enlargement, moderate or severe | 19/313 | 90 (6799) | 74 (6879) | 3.4 (2.54.3) | 0.1 (0.040.4) |
| Left ventricular hypertrophy, moderate or severe | 33/314 | 70 (5184) | 73 (6778) | 2.5 (1.83.3) | 0.4 (0.20.7) |
| Pericardial effusion, moderate or large | 3/314 | 100 (29100) | 95 (9297) | 21 (6.731) | 0 (00.6) |
| Inferior vena cava, dilated | 45/284 | 56 (4070) | 86 (8190) | 4.0 (2.66.0) | 0.5 (0.40.7) |
LV systolic dysfunction and IVC dilatation were both prevalent enough to meet our criterion to examine interobserver variability; the mean number of abnormal patients per hospitalist was 10 patients for LV systolic dysfunction and 6 patients for IVC dilatation. For LV systolic dysfunction, SDs around mean sensitivity (84%) and specificity (87%) were 12% and 6%, respectively. For IVC dilatation, SDs around mean sensitivity (58%) and specificity (86%) were 24% and 7%, respectively.
Discussion
We found that, after a 27‐hour training program, hospitalists performed HCUE with moderate to excellent diagnostic accuracy for 6 important cardiac abnormalities. For example, hospitalists' assessments of LV systolic function yielded positive and negative likelihood ratios of 6.9 (95% CI, 4.99.8) and 0.2 (95% CI, 0.10.3), respectively. At the bedsides of patients with acute heart failure, therefore, hospitalists could use HCUE to lower or raise the 50:50 chance of LV systolic dysfunction30 to 15% or 85%, respectively. Whether or not these posttest likelihoods are extreme enough to cross important thresholds will depend on the clinical context. Yet these findings demonstrate how HCUE has the potential to provide hospitalists with valuable point‐of‐care data that are otherwise unavailableeither because routine clinical assessments are unreliable31 or because echocardiographic services are not immediately accessible.1
In fact, recent data from the Joint Commission on Accreditation of Healthcare Organizations shows how inaccessible SE may be. Approximately one‐quarter of hospitals in the United States send home about 10% of patients with acute heart failure without echocardiographic assessment of LV systolic function before, during, or immediately after hospitalization.32 In doing so, these hospitals leave unmet the 2002 National Quality Improvement Goal of universal assessment of LV systolic function for all heart failure patients. Hospitalists could close this quality gap with routine, 10‐minute HCUE assessments in all patients admitted with acute heart failure. (Our research HCUE protocol required a median time of 28 minutes, but this included time to assess 5 other cardiac abnormalities and collect data for research purposes). Until the clinical consequences of introducing hospitalist‐performed HCUE are studied, potential benefits like this are tentative. But our findings suggest that training hospitalists to accurately perform HCUE can be successfully accomplished in just 27 hours.
Other studies of HCUE training programs for noncardiologists have also challenged the opinion that learning to perform HCUE requires more than 100 hours of training.2, 711 Yet only 1 prior study has examined an HCUE training program for hospitalists.5 In this study by Martin et al.,5 hospitalists completed 5 supervised HCUE examinations and 6 hours of interpretation training before investigators scored their image acquisition and interpretation skills from 30 unsupervised HCUE examinations. To estimate their final skill levels at the completion of all 35 examinations by accounting for an initially steep learning curve, investigators then adjusted these scores with regression models. Despite these upward adjustments, hospitalists' image acquisition and interpretation scores were low in comparison to echocardiographic technicians and cardiology fellows. Besides these adjusted measurements of hospitalists' skills, however, Martin et al.5 unfortunately did not also report standard measures of diagnostic accuracy, like those proposed by the Standards for Reporting of Diagnostic Accuracy (STARD) initiative.33 Therefore, direct comparisons to the present study are difficult. Nevertheless, their findings suggest that a training program limited to 5 supervised HCUE examinations may be inadequate for hospitalists. In fact, the same group's earlier study of medical trainees suggested a minimum of 30 supervised HCUE examinations.9 We chose to design our hospitalist training program based on this minimum, though they surprisingly did not.5 As others continue to refine the components of hospitalist HCUE training programs, such as the optimal number of supervised examinations, our program could serve as a reasonable comparative example: more rigorous than the program designed by Martin et al.5 but more feasible than ASE level 1 training.
The number and complexity of assessments taught in HCUE training programs will determine their duration. With ongoing advancements in HCUE technology, there is a growing list of potential assessments to choose from. Although HCUE training programs ought to include assessments with proven clinical applications, there are no trials of HCUE‐directed care to inform such decisions. In their absence, therefore, we chose 6 assessments based on the following 3 criteria. First, our assessments were otherwise not reliably available from routine clinical data, such as the physical examination. Second, our assessments were straightforward: easy to learn and simple to perform. Here, we based our reasoning on an expectation that the value of HCUE lies not in highly complex, state‐of‐the‐art assessmentswhich are best left to echocardiographers equipped with SEbut in simple, routine assessments made with highly portable machines that grant noncardiologists newfound access to point‐of‐care data.34 Third, our assessments were clinically pertinent and, where appropriate, defined by cut‐points at levels of severity that often lead to changes in management. We suspect that setting high cut‐points has the salutary effects of making assessments easier to learn and more accurate, because distinguishing mild abnormalities is likely the most challenging aspect of echocardiographic interpretation.35 Whether or not our choices of assessments, and their cut‐points, are optimal has yet to be determined by future research designed to study how they affect patient outcomes. Given our hospitalists' performance in the present study, these assessments seem worthy of such future research.
Our study had several limitations. We studied physicians and patients from only 1 hospital; similar studies performed in different settings, particularly among patients with different proportions and manifestations of disease, may find different results. Nevertheless, our sampling method of prospectively enrolling consecutive patients strengthens our findings. Some echocardiographic measurement methods used by our hospitalists differed in subtle ways from echocardiography guideline recommendations.35 We chose our methods (Table 2) for 2 reasons. First, whenever possible, we chose methods of interpretation that coincided with our local cardiologists'. Second, we chose simplicity over precision. For example, the biplane method of disks, or modified Simpson's rule, is the preferred volumetric method of calculating LA size.35 This method requires tracing the contours of the LA in 2 planes and then dividing the LA volume into stacked oval disks for calculation. We chose instead to train our hospitalists in a simpler method based on 2 linear measurements. Any loss of precision, however, was balanced by a large gain in simplicity. Regardless, minor variations in LA size are not likely to affect hospitalists' bedside evaluations. Finally, we did not validate the results of our reference standard (SE) by documenting interobserver reliability. Yet, because SE is generally accurate for the 6 cardiac abnormalities under study, the effect of this bias should be small.
These limitations can be addressed best by controlled trials of HCUE‐directed care. These trials will determine the clinical impact of hospitalist‐performed HCUE and, in turn, inform our design of HCUE training programs. As the current study shows, training hospitalists to participate in such trials is feasible: like other groups of noncardiologists, hospitalists can accurately perform HCUE after a brief training program. Whether or not hospitalists should perform HCUE requires further study.
Acknowledgements
The authors thank Sonosite, Inc., Bothell, WA, for loaning us 2 MicroMaxx machines throughout the study period. They also thank the staff of the Internal Medicine Research Mentoring Program at Rush Medical College for their technical support and the staff of the Division of Neurology at Stroger Hospital for granting them access to a procedure room.
- .The physical examination of the future: echocardiography as part of the assessment.ACC Curr J Rev.1998;7:79–81.
- ,,.The hand‐carried echocardiographic device as an aid to the physical examination.Echocardiography.2003;20:477–485.
- ,.Bedside ultrasonography in the ICU: Part 2.Chest.2005;128:1766–1781.
- ,.Practical Guide to Emergency Ultrasound.1st ed.Philadelphia, PA:Lippincott Williams 2006.
- ,,,,,.Hospitalist performance of cardiac hand‐carried ultrasound after focused training.Am J Med.2007;120:1000–1004.
- ,,, et al.Hand‐carried cardiac ultrasound (HCU) device: recommendations regarding new technology. A report from the echocardiography task force on new technology of the Nomenclature and Standards Committee of the American Society of Echocardiography.J Am Soc Echocardiogr.2002;15:369–373.
- ,,,,,.The use of small personal ultrasound devices with internists without formal training in echocardiography.Eur J Echocardiogr.2003;4:141–147.
- ,,, et al.Feasibility of point‐of‐care echocardiography by internal medicine house staff.Am Heart J.2004;147:476–481.
- ,,,,,.The rate at which residents learn to use hand‐held echocardiography at the bedside.Am J Med.2005;118:1010–1018.
- ,,, et al.Comparison of effectiveness of hand‐carried ultrasound to bedside cardiovascular physical examination.Am J Cardiol.2005;96:1002–1006.
- ,,.Can hand‐carried ultrasound devices be extended for use by the noncardiology medical community?Echocardiography.2003;20:471–476.
- ,,, et al.A hospitalist‐run short stay unit: features that predict patients' length‐of‐stay and eventual admission to traditional inpatient services.J Hosp Med.2009;4:276–284.
- .Adult echocardiography scanning protocol. In: Templin BB, ed.Ultrasound Scanning: Principles and Protocols.2nd ed.Philadelphia, PA:Saunders;1999:426.
- ,,, et al.ACCF 2008 Recommendations for training in adult cardiovascular medicine core cardiology training (COCATS 3) (revision of the 2002 COCATS training statement).J Am Coll Cardiol.2008;51:333–414.
- ,,.The Echo Manual.2nd ed.Philadelphia, PA:Lippincott Williams 1999.
- ,,, et al.Echocardiography in serial evaluation of left ventricular systolic and diastolic function: importance of image acquisition, quantitation, and physiologic variability in clinical and investigational applications.J Am Soc Echocardiogr.1991;4:203–214.
- .Textbook of Clinical Echocardiography.3rd ed.Philadelphia, PA:Elsevier Saunders;2004.
- ,,.Likelihood ratios with confidence: sample size estimation for diagnostic test studies.J Clin Epidemiol.1991;44:763–770.
- ,,, et al.ACC/AHA 2005 guideline update for the diagnosis and management of chronic heart failure in the adult: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines.Circulation.2005;112;154–235.
- ,,, et al.ACC/AHA 2006 guidelines for the management of patients with valvular heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines.Circulation.2006;114:e84–e231.
- ,,, et al.Left atrial size: physiologic determinants and clinical applications.J Am Coll Cardiol.2006;47:2357–2363.
- ,,,,.Prognostic implications of echocardiographically determined left ventricular mass in the Framingham Heart Study.N Engl J Med.1990;322:1561–1566.
- ,,,.Does this patient with a pericardial effusion have cardiac tamponade?JAMA.2007;297:1810–1818.
- .Acute cardiac tamponade.N Engl J Med.2003;349:685–690.
- ,,,,,.Evaluation of size and dynamics of the inferior vena cava as an index of right‐sided cardiac function.Am J Cardiol.1984;53:579–585.
- ,,.The influence of uninterpretability on the assessment of diagnostic tests.J Chronic Dis.1986;39:575–584.
- ,,.Relations between effectiveness of a diagnostic test, prevalence of the disease, and percentages of uninterpretable results. An example in the diagnosis of jaundice.Med Decis Making.1982;2:285–297.
- .Confidence intervals for the ratio of two binomial proportions.Biometrics.1984;40:513–517.
- ,,.Comparing the areas under two or more correlated receiver operating curves: a nonparametric approach.Biometrics.1988;44:837–845.
- ,,, et al.Systolic blood pressure at admission, clinical characteristics, and outcomes in patients hospitalized with acute heart failure.JAMA.2006;296:2217–2226.
- ,,, et al.Utility of history, physical examination, electrocardiogram, and chest radiograph for differentiating normal from decreased systolic function in patients with heart failure.Am J Med.2002;112:437–445.
- Joint Commission on Accreditation of Healthcare Organizations. Health Care Quality Data Download Website. Available at: http://www.healthcarequalitydata.org. Accessed December2008.
- ,,, et al.Towards complete and accurate reporting of studies of diagnostic accuracy: the STARD initiative.Clin Chem.2003;49:1–6.
- ,,.Will disruptive innovations cure health care?Harv Bus Rev.2000;78:102–112.
- ,,, et al.Recommendations for chamber quantification: a report from the American Society of Echocardiography's Guidelines and Standards Committee and the Chamber Quantification Writing Group, developed in conjunction with the European Association of Echocardiography, a branch of the European Society of Cardiology.J Am Soc Echocardiogr.2005;18:1440–1463.
- .The physical examination of the future: echocardiography as part of the assessment.ACC Curr J Rev.1998;7:79–81.
- ,,.The hand‐carried echocardiographic device as an aid to the physical examination.Echocardiography.2003;20:477–485.
- ,.Bedside ultrasonography in the ICU: Part 2.Chest.2005;128:1766–1781.
- ,.Practical Guide to Emergency Ultrasound.1st ed.Philadelphia, PA:Lippincott Williams 2006.
- ,,,,,.Hospitalist performance of cardiac hand‐carried ultrasound after focused training.Am J Med.2007;120:1000–1004.
- ,,, et al.Hand‐carried cardiac ultrasound (HCU) device: recommendations regarding new technology. A report from the echocardiography task force on new technology of the Nomenclature and Standards Committee of the American Society of Echocardiography.J Am Soc Echocardiogr.2002;15:369–373.
- ,,,,,.The use of small personal ultrasound devices with internists without formal training in echocardiography.Eur J Echocardiogr.2003;4:141–147.
- ,,, et al.Feasibility of point‐of‐care echocardiography by internal medicine house staff.Am Heart J.2004;147:476–481.
- ,,,,,.The rate at which residents learn to use hand‐held echocardiography at the bedside.Am J Med.2005;118:1010–1018.
- ,,, et al.Comparison of effectiveness of hand‐carried ultrasound to bedside cardiovascular physical examination.Am J Cardiol.2005;96:1002–1006.
- ,,.Can hand‐carried ultrasound devices be extended for use by the noncardiology medical community?Echocardiography.2003;20:471–476.
- ,,, et al.A hospitalist‐run short stay unit: features that predict patients' length‐of‐stay and eventual admission to traditional inpatient services.J Hosp Med.2009;4:276–284.
- .Adult echocardiography scanning protocol. In: Templin BB, ed.Ultrasound Scanning: Principles and Protocols.2nd ed.Philadelphia, PA:Saunders;1999:426.
- ,,, et al.ACCF 2008 Recommendations for training in adult cardiovascular medicine core cardiology training (COCATS 3) (revision of the 2002 COCATS training statement).J Am Coll Cardiol.2008;51:333–414.
- ,,.The Echo Manual.2nd ed.Philadelphia, PA:Lippincott Williams 1999.
- ,,, et al.Echocardiography in serial evaluation of left ventricular systolic and diastolic function: importance of image acquisition, quantitation, and physiologic variability in clinical and investigational applications.J Am Soc Echocardiogr.1991;4:203–214.
- .Textbook of Clinical Echocardiography.3rd ed.Philadelphia, PA:Elsevier Saunders;2004.
- ,,.Likelihood ratios with confidence: sample size estimation for diagnostic test studies.J Clin Epidemiol.1991;44:763–770.
- ,,, et al.ACC/AHA 2005 guideline update for the diagnosis and management of chronic heart failure in the adult: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines.Circulation.2005;112;154–235.
- ,,, et al.ACC/AHA 2006 guidelines for the management of patients with valvular heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines.Circulation.2006;114:e84–e231.
- ,,, et al.Left atrial size: physiologic determinants and clinical applications.J Am Coll Cardiol.2006;47:2357–2363.
- ,,,,.Prognostic implications of echocardiographically determined left ventricular mass in the Framingham Heart Study.N Engl J Med.1990;322:1561–1566.
- ,,,.Does this patient with a pericardial effusion have cardiac tamponade?JAMA.2007;297:1810–1818.
- .Acute cardiac tamponade.N Engl J Med.2003;349:685–690.
- ,,,,,.Evaluation of size and dynamics of the inferior vena cava as an index of right‐sided cardiac function.Am J Cardiol.1984;53:579–585.
- ,,.The influence of uninterpretability on the assessment of diagnostic tests.J Chronic Dis.1986;39:575–584.
- ,,.Relations between effectiveness of a diagnostic test, prevalence of the disease, and percentages of uninterpretable results. An example in the diagnosis of jaundice.Med Decis Making.1982;2:285–297.
- .Confidence intervals for the ratio of two binomial proportions.Biometrics.1984;40:513–517.
- ,,.Comparing the areas under two or more correlated receiver operating curves: a nonparametric approach.Biometrics.1988;44:837–845.
- ,,, et al.Systolic blood pressure at admission, clinical characteristics, and outcomes in patients hospitalized with acute heart failure.JAMA.2006;296:2217–2226.
- ,,, et al.Utility of history, physical examination, electrocardiogram, and chest radiograph for differentiating normal from decreased systolic function in patients with heart failure.Am J Med.2002;112:437–445.
- Joint Commission on Accreditation of Healthcare Organizations. Health Care Quality Data Download Website. Available at: http://www.healthcarequalitydata.org. Accessed December2008.
- ,,, et al.Towards complete and accurate reporting of studies of diagnostic accuracy: the STARD initiative.Clin Chem.2003;49:1–6.
- ,,.Will disruptive innovations cure health care?Harv Bus Rev.2000;78:102–112.
- ,,, et al.Recommendations for chamber quantification: a report from the American Society of Echocardiography's Guidelines and Standards Committee and the Chamber Quantification Writing Group, developed in conjunction with the European Association of Echocardiography, a branch of the European Society of Cardiology.J Am Soc Echocardiogr.2005;18:1440–1463.
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