To characterize the impact of bronchodilation on i) exercise tolerance ii) cardiopulmonary response and iii) dynamic hyperinflation following an endurance shuttle walking test in patients with mild COPD.
In a randomized double-blind cross-over trial, 37 patients with GOLD stage I COPD (FEV1, 96?¡À?2 % predicted, mean?¡À?SEM) completed an endurance shuttle walking test up to exhaustion 90?¡À?15?min following nebulization of a placebo [NaCl] or of ipratropium bromide/salbutamol sulfate (500?¦Ìg/2.5?mg) combination.
FEV1 significantly increased following bronchodilation compared with placebo (0.17?¡À?0.02 vs. ?0.02?¡À?0.01?L, p?<?0.0001, mean?¡À?SEM). The difference in walking endurance time between bronchodilation and placebo was not statistically significant (¦¤15?¡À?12?s, p?=?0.21), with the upper and lower boundaries of the 95 % confidence interval [?9-40?s, 95 % CI] within the proposed minimally important difference for this variable (65?s). The ratio of breathing frequency to tidal volume tended to be decreased with bronchodilation during exercise (p?=?0.07), indicating a deeper and slower breathing pattern with bronchodilation. Bronchodilation had a significant effect on dynamic hyperinflation at isotime and at peak exercise.
Bronchodilation did not improve walking endurance in patients with mild COPD despite small physiological benefits of uncertain clinical relevance.