SAN DIEGO – Use of noninvasive ventilation during an exercise session in hypercapnic patients with very severe chronic obstructive pulmonary disease (COPD) led to a clinically relevant increase in endurance time, a randomized trial showed.
At an international conference of the American Thoracic Society, lead study author Tessa Schneeberger noted that nocturnal noninvasive ventilation (NIV) in hypercapnic COPD patients has been shown to improve quality of life and survival (Lancet Resp Med. 2014;2[9]:698-705). Another study found that NIV with unchanged nocturnal settings during a 6-minute walk test in hypercapnic COPD patients can increase oxygenation, decrease dyspnea, and increase walking distance (Eur Respir J. 2007;29:930-6).
Tessa Schneeberger
For the current study, Ms. Schneeberger, a physiotherapist at the Institute for Pulmonary Rehabilitation Research, Schoenau am Koenigssee, Germany, and her associates set out to investigate short-term effects of using NIV during exercise in hypercapnic patients with very severe COPD, as part of a 3-week inpatient physical rehabilitation program. The researchers limited their analysis to 20 Global Initiative for Chronic Obstructive Lung Disease stage IV patients aged 40-80 years with a carbon dioxide partial pressure (PCO2) of greater than 50 mm Hg at rest and/or during exercise and who were non-naive to NIV, and excluded patients with concomitant conditions that make cycling impossible, those with acute exacerbations, and those with exercise-limiting cardiovascular diseases.
The day after an initial incremental cycle ergometer test, patients performed two constant work rate tests (CWRT) at 60% of the peak work rate, with and without NIV, in randomized order and with a resting time of 1 hour between tests. The inspiratory positive airway pressure (IPAP) was individually adjusted from each patient’s nocturnal settings to provide sufficient pressure to relieve the work on breathing muscles and to decrease transcutaneous PCO2 (TcPCO2) levels during NIV. The primary outcome was cycle endurance time. Other outcomes of interest were TcPCO2, oxygen saturation (SpO2) and perceived dyspnea/leg fatigue via the 10-point Borg scale during CWRTs.
The mean age of the study participants was 60 years, their mean body mass index was 23 kg/m2, their mean forced expiratory volume in1 second was 19% predicted, their mean PaCO2 was 51 mm Hg, their mean PaO2 was 54.5 mm Hg, their mean distance on the 6-minute walk test was 243 meters, and their mean peak work rate was 42 watts.
NIV via full face mask and assisted pressure control ventilation mode was performed with mean IPAP/expiratory PAP levels of 27/6 cm H2O.
During CWRTs patients cycled with NIV for 663 seconds and without NIV for 476 seconds, a significant difference (P = .013) and one that was clinically relevant. At isotime (the time of CWRT with shortest duration), TcPCO2 was significantly lower with NIV (a mean of –6.1 mm Hg), while SpO2 was significantly higher with NIV (a mean of 3.6%). In addition, after CWRT, NIV patients perceived less dyspnea (P = .008) with comparable leg fatigue (P = .79).
“We found that NIV during cycling exercise in hypercapnic patients with very severe COPD can lead to an acutely significant increase in exercise duration, with lower TcPCO2 and a reduced sensation of dyspnea,” Ms. Schneeberger concluded. “It can be performed with high-pressure assisted-controlled ventilation comparable as that used nocturnally to effectively reduce TcPCO2 in people with COPD.”
She emphasized that this approach requires appropriate equipment and special staff expertise for setup titration. “We will continue this research to look into the underlying physiological mechanisms to define nonresponders and responders, and also to look how at this might improve outcomes of an exercise training program.”
Ms. Schneeberger reported having no financial disclosures.