| Description: |
BACKGROUND: This study assessed the clinical effects of a ventilatory assist (VA) device in addition to supplemental O 2 (VA+O 2 ) 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+O 2 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 O 2 /VA+O 2 were established. At visit 2, subjects exercised at a constant work rate of 80% peak work rate to maximum endurance after allocation to VA+O 2 or O 2 . Cardiorespiratory variables, work rate, and dyspnea were included to define potential clinical benefits of VA+O 2 . Data were analyzed using a linear mixed model. RESULTS: Fifteen subjects with COPD (mean ± SD, age 67.9 ± 9.0 y, FEV 1 0.89 ± 0.35 observed) completed the study. Exercise duration in minutes was significantly longer with VA+O 2 versus O 2 (least squares mean [standard error], 12.0 [2.0] vs 6.2 [2.0], P = .01). VA+O 2 versus O 2 was also associated with significantly greater isotime improvements in Borg dyspnea scores (3.6 [0.5] vs 5.7 [0.5] , P < .001), S pO 2 (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+O 2 significantly increased exercise time and improved dyspnea, S pO 2 , breathing frequency, and leg fatigue versus O 2 alone. |