Effect of a Ventilatory Assist Device in Addition to Supplemental Oxygen on Exercise Endurance in Subjects With COPD

Abstract

Background: This study assessed the clinical effects of a ventilatory assist (VA) device in addition to supplemental O₂ (VA+O₂) on exercise endurance in subjects with severe to very severe COPD managed with long-term oxygen therapy (LTOT).

Methods: This was a crossover clinical feasibility study of the effects of VA+O₂ in subjects with severe to very severe COPD managed with LTOT (N = 15). At visit 1, physiologic measures were obtained, and subjects were tested on the cycle ergometer with VA. Peak work rate and flow for continuous supplemental O₂/VA+O₂ were established. At visit 2, subjects exercised at a constant work rate of 80% peak work rate to maximum endurance after allocation to VA+O₂ or O₂. Cardiorespiratory variables, work rate, and dyspnea were included to define potential clinical benefits of VA+O₂. Data were analyzed using a linear mixed model.

Results: Fifteen subjects with COPD (mean ± SD, age 67.9 ± 9.0 y, FEV₁ 0.89 ± 0.35 observed) completed the study. Exercise duration in minutes was significantly longer with VA+O₂ versus O₂ (least squares mean [standard error], 12.0 [2.0] vs 6.2 [2.0], P = .01). VA+O₂ versus O₂ was also associated with significantly greater isotime improvements in Borg dyspnea scores (3.6 [0.5] vs 5.7 [0.5], P < .001), S_pO2 (96.9 [0.9] vs 91.4 [0.9], P < .001), leg fatigue scores (3.8 [0.6] vs 5.2 [0.6], P = .008), and breathing frequency (22.8 [0.9] vs 25.8 [0.9] breaths/min, P = .01). There were no differences in heart rate.

Conclusions: In symptomatic subjects with severe to very severe COPD, VA+O₂ significantly increased exercise time and improved dyspnea, S_pO2 , breathing frequency, and leg fatigue versus O₂ alone.

Keywords: COPD; dyspnea; exercise endurance; leg fatigue; oxygen therapy; pulmonary ventilation.