[Effects of aerosol oxitropium bromide and fenoterol on maximal exercise capacity in chronic obstructive pulmonary disease and their correlation with air flow during exercise and with parameters of maximal exercise].

To examine the effects of bronchodilators on maximal exercise capacity and their correlation with airflow during exercise in patients with chronic obstructive pulmonary disease (COPD), we conducted a double-blind, randomized comparison between inhaled fenoterol (beta 2-agonist) and oxitropium bromide (anticholinergic agent) in 8 patients with stable COPD (mean age 73 years, mean FEV1 1.1 L, mean FEV1% 50%). Only oxitropium bromide resulted in statistically significant improvement in FEV1 40 min after inhalation. On maximal exercise, fenoterol did not affect oxygen uptake (VO2 max), minute ventilation (VEmax), respiratory frequency (Rfmax), ventilatory efficacy (VEmax/VO2 max), peak expiratory flow during exercise (PEFmax), heart rate (HRmax) and dyspnea (Borg Scale Slope). After oxitropium bromide, dyspnea during exercise and HRmax decreased significantly, but PEFmax and other parameters did not change significantly compared with control. There was no correlation between changes in dyspnea during exercise and changes in FEV1 and PEFmax after oxitropium bromide inhalation. We conclude that inhaled oxitropium bromide, an anticholinergic agent, reduces dyspnea during exercise in patients with COPD. This favorable effect was not due to change of airflow limitation during exercise, and other factors can thus influence reduction of dyspnea during exercise in these patients.