Introduction: Inhaled anticholinergic drugs are often recommended for use as a first-line therapy for patients with COPD because they provide similar or more effective bronchodilating actions, as well as fewer side effects. It is not known, however, which class of bronchodilators is more advantageous for pulmonary hemodynamics, particularly during exercise.
Objectives: To compare the effects of oxitropium and fenoterol on pulmonary hemodynamics in patients with COPD at rest and during exercise.
Patients: The study participants consisted of 20 consecutive male patients with stable COPD, a mean (+/- SD) age of 68+/-8 years old, and an FEV1/FVC ratio of 47.5+/-10.0%.
Methods: Eleven patients inhaled two puffs of oxitropium, and nine patients inhaled two puffs of fenoterol. Seven members of each group performed incremental exercise using a cycle ergometer. The hemodynamic measurements with right heart catheterization were performed by taking the average of three consecutive respiratory cycles before and after the administration of inhaled bronchodilators at rest and during exercise.
Results: At rest, despite a similar improvement of spirometric data with the two drugs, fenoterol, not oxitropium, caused significant increases in heart rate and cardiac output, a decrease in pulmonary vascular resistance, and a deteriorated Pao2. During exercise, however, both drugs similarly attenuated elevations in the mean pulmonary arterial pressure (40+/-12 to 38+/-10 mm Hg by oxitropium, and 41+/-9 to 36+/-9 mm Hg by fenoterol), the mean pulmonary capillary wedge pressure, and the mean right atrial pressure.
Conclusion: Our findings indicate that both classes of bronchodilators are equally beneficial in the attenuation of right heart afterload during exercise in patients with COPD.