Managing severe asthma exacerbations in the ED: We need answers beyond albuterol

^CHEST

Dr. Nicholas E. Ghionni

Evidence-based medicine (EBM) stems from making the best patient-centered decision from the highest-quality data available that comports with our understanding of pathophysiology. In some situations, clinicians are forced to draw conclusions from data that are imperfect and apply it to patients who are complex and dynamic. For most pathologies, available data provides some direction. There is, however, one pathophysiologic state that remains understudied, precarious, and common.

The Centers for Disease Control and Prevention (CDC) estimates that about 7.7% of the United States population has asthma. There were about 1 million ED visits in 2020, with asthma listed as the primary diagnosis, and only 94,000 required hospitalization.¹ There are many tools we employ that have greatly decreased inpatient admissions for asthma. The uptake of inhaled corticosteroids (ICS) has significantly reduced asthma-related morbidity and mortality and reduced exacerbations that require admission to a hospital. This treatment strategy is supported by the Global Initiative for Asthma (GINA) and National Asthma Education and Prevention Program (NAEPP) guidelines.^2,3 While we should celebrate the impact that EBM and ICS have had on asthma outcomes, we continue to struggle to control severe asthma.

Bronchodilator therapy in the hospital is ubiquitous. House staff and hospitalists click the bronchodilator order set early and often. However, the optimal frequency, dose, and duration of inhaled bronchodilator therapy for acute asthma exacerbation are unknown. Do frequency, dose, and duration change with exacerbation severity? Nothing gets ED, inpatient, or ICU physicians more jittery than the phrase “exacerbation of asthma on BiPap” or “intubated for asthma.” With its enormous clinical impact and notoriously difficult hospital and ICU course, the lack of evidence we have for managing these patients outside of the initial 24- to 48-hour visit is concerning. Neither NAEPP nor GINA provide management recommendations for the patient with severe asthma exacerbation that necessitates admission.

Albuterol is a commonly used medication for asthma and chronic obstructive airway disease. It is rapid acting and effective—few medications give patients (or clinicians) such instant satisfaction. As an internal medicine resident and pulmonary fellow, I ordered it countless times without ever looking at the dose. Sometimes, patients would come up from the emergency department after receiving a “continuous dose.” I would often wonder exactly what that meant. After some investigation, I found that in my hospital at the time, one dose of albuterol was 2.5 mg in 2 mL, and a continuous nebulization was four doses for a total of 10 mg.

Shrestha et al. found that high-dose albuterol (7.5 mg) administered continuously was superior to 2.5 mg albuterol delivered three times over 1.5 hours. There were demonstrable improvements in FEV₁ and no ICU admissions.⁴ This study is one of many that compared intermittent to continuous and high-dose vs low-dose albuterol in the emergency department. Most are small and occur over the first 24 hours of presentation to the hospital. They often use short-term changes in spirometry as their primary outcome measure. Being a pulmonary and critical care doctor, I see patients who require advanced rescue maneuvers such as noninvasive positive pressure ventilation (NIPPV) or other pharmacologic adjuncts, for which the current evidence is limited.

Because studies of inhaled bronchodilators in acute asthma exacerbation use spirometry as their primary outcome, those with more severe disease and higher acuity are excluded. Patients on NIPPV can’t perform spirometry. There is essentially no literature to guide treatment for a patient with asthma in the adult ICU. In pediatric intensive care units, there are some data to support either continuous or intermittent inhaled bronchodilator that extends beyond the initial ED visit up to about 60 hours.⁵ Much of the pediatric data revolve about the amount of albuterol given, which can be as high as 75 mg/hr though is typically closer to 10-20 mg/hr.⁶ This rate is continued until respiratory improvement occurs.

With poor evidence to guide us and no specific direction from major guidelines, how should providers manage severe asthma exacerbation? The amount of drug deposited in the lung varies by the device used to deliver it. For nebulization, only about 10% of the nebulized amount reaches the lungs for effect; this is a smaller amount compared with all other devices one could use, such as MDI or DPI.⁷ Once a patient with asthma reaches the emergency department, that person is usually placed on some form of nebulizer treatment. But based on local hospital protocols, the amount and duration can vary widely. Sometimes, in patients with severe exacerbation, there is trepidation to continuing albuterol therapy due to ongoing tachycardia. This seems reasonable given increased albuterol administration could beget an ongoing cycle of dyspnea and anxiety. It could also lead to choosing therapies that are less evidence based.

In closing, this seemingly mundane topic takes on new meaning when a patient is in severe exacerbation. Fortunately, providers are not often faced with the decision to wade into the evidence-free territory of severe asthma exacerbation that is unresponsive to first-line treatments. This narrative should serve as a general alert that this pathophysiologic state is understudied. When encountered, thoughtful consideration of pathology, physiology, and pharmacology is required to reverse it.

References

1. Centers for Disease Control and Prevention. (2023, May 10). Most recent national asthma data. Centers for Disease Control and Prevention. https://www.cdc.gov/asthma/most_recent_national_asthma_data.htm

2. Global Initiative for Asthma - GINA. (2023, August 15). 2023 GINA Main Report - Global Initiative for Asthma - GINA. https://ginasthma.org/2023-gina-main-report/

3. Kiley J, Mensah GA, Boyce CA, et al (A Report from the National Asthma Education and Prevention Program Coordinating Committee Expert Panel Working Group). 2020 Focused updates to the: Asthma Management Guidelines. US Department of Health and Human Services, NIH, NHLBI 2020.

4. Shrestha M, Bidadi K, Gourlay S, Hayes J. Continuous vs intermittent albuterol, at high and low doses, in the treatment of severe acute asthma in adults. Chest. 1996 Jul;110(1):42-7. doi: 10.1378/chest.110.1.42. PMID: 8681661.

5. Kulalert P, Phinyo P, Patumanond J, Smathakanee C, Chuenjit W, Nanthapisal S. Continuous versus intermittent short-acting β2-agonists nebulization as first-line therapy in hospitalized children with severe asthma exacerbation: a propensity score matching analysis. Asthma Res Pract. 2020 Jul 2;6:6. doi: 10.1186/s40733-020-00059-5. PMID: 32632352; PMCID: PMC7329360.

6. Phumeetham S, Bahk TJ, Abd-Allah S, Mathur M. Effect of high-dose continuous albuterol nebulization on clinical variables in children with status asthmaticus. Pediatr Crit Care Med. 2015 Feb;16(2):e41-6. doi: 10.1097/PCC.0000000000000314. PMID: 25560428.

7. Gardenhire DS, Burnett D, Strickland S, Myers, TR. A guide to aerosol delivery devices for respiratory therapists. American Association for Respiratory Care, Dallas, Texas 2017.