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 5 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 6 SD, age 67.9 6 9.0 y, FEV1 0.89 6 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 5 .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), SpO2 (96.9 [0.9] vs 91.4 [0.9],