Bi-level Positive Airway Pressure (BiPAP) with Standard Exhalation Valve Does Not Improve Maximum Exercise Capacity in Patients with COPD

Abstract

Background: Although BiPAP has been used as an adjunct to exercise, little is know about its effect on exercise in COPD. We aimed to evaluate the acute effect of BiPAP delivered with a standard valve (Vision, Respironics), compared to no assist, on exercise capacity in individuals with COPD. Methods: Peak exercise workload (WL_peak), dyspnea (Borg), end-expiratory lung volume (EELV), tidal volume (V_T), minute ventilation (V_E), O₂ uptake (VO₂), and CO₂ production (VCO₂) were assessed in 10 COPD patients (FEV₁ 53 ± 22% pred) during three symptom-limited bicycle exercise tests while breathing i) without a ventilator (noPS), ii) with a pressure support (PS) of 0 cm H₂O (PS0; IPAP & EPAP 4 cm H₂O) and iii) PS of 10 cm H₂O (PS10; IPAP 14 & EPAP 4 cm H₂O) on separate days using a randomized crossover design. Results: WL_peak was significantly lower with PS10 (33 ± 16) and PS0 (30.5 ± 13) than noPS (43 ± 19) (p < 0.001). Dyspnea at peak exercise was similar with noPS, PS0 and PS10; at isoload it was lower with noPS compared to PS10 and PS0 (p < 0.01). V_T and V_E were highest with PS10 and lowest with noPS both at peak exercise and isoload (p < 0.001). EELV was similar at peak exercise with all three conditions. VO₂ and VCO₂ were greater with PS10 and PS0 than noPS (p < 0.001), both at peak exercise and isoload. Conclusion: Use of BiPAP with a standard exhalation valve during exercise increases V_T and V_E at the expense of augmenting VCO₂ and dyspnea, which in turns reduces WL_peak in COPD patients.

Keywords:

• BiPAP
• COPD
• exercise
• mechanical ventilation
• pulmonary rehabilitation
• ventilator support

Acknowledgment

The authors would like to thank V. Rose from the Jewish Rehabilitation Hospital, Laval and the Pneumology Department at HÙpital du SacrÈ-Cúur de MontrÈal for their assistance with patient recruitment and PFT assessment.