Effect of Albuterol on Maximal Exercise Capacity in Cystic Fibrosis

BackgroundInhaled, short-acting β-adrenergic agonists (SAβAs) are widely prescribed in cystic fibrosis (CF) subjects, despite a lack of convincing data for efficacy and the potential for these agents to result in airway instability. We tested the hypothesis that inhaled albuterol would improve maximal exercise performance in CF subjects with airflow obstruction, as a result of acute bronchodilation.MethodsRandomized, double-blind, placebo-controlled crossover study of the effect of inhaled albuterol on maximal exercise performance in 20 stable adult CF patients (mean ± SD age, 23.3 ± 6.1 years; FEV1, 57.65 ± 17.13% of predicted).ResultsVentilatory limitation to exercise was demonstrated in 16 subjects (80%). Significant bronchodilation occurred with exercise alone (end-exercise FEV1, 2.24 ± 0.8 L; vs preexercise FEV1, 2.09 ± 0.77 L; p < 0.0001), but albuterol resulted in significantly greater exercise-induced bronchodilation than placebo (change in FEV1, 0.3 ± 0.15 L vs 0.15 ± 0.11 L; 95% confidence interval [CI], + 0.07 to + 0.23; p < 0.001). However, there was no difference in maximal workload achieved (albuterol, 158 ± 46 W; vs placebo, 158 ± 45 W; 95% CI, − 4.41 to + 4.71; p = 0.95), nor any other measure of exercise performance including maximal oxygen uptake.ConclusionsDespite causing significant acute bronchodilation, inhaled albuterol did not improve maximal exercise performance in ventilatory-limited CF adults, adding to the body of literature that fails to show any clinical benefit of SAβAs in CF subjects. The current results provide further evidence to question the widespread use of these agents, although the potential for adrenergic β-agonists to instead improve submaximal exercise performance merits further investigation.