Effects of Oxygen on Exercise Duration in Chronic Obstructive Pulmonary Disease Patients before and after Pulmonary Rehabilitation
BACKGROUND: Supplemental oxygen therapy has been shown to improve exercise performance in patients with chronic obstructive pulmonary disease (COPD). It is unknown whether the magnitude of this benefit would be affected by participation in a pulmonary rehabilitation program.OBJECTIVE: To compare the effects of supplemental oxygen on exercise capacity in nonhypoxemic COPD patients before and after participation in a pulmonary rehabilitation program.METHODS: Sixteen patients with COPD underwent two pairs of constant-load exercise tests before and after participation in a three-month outpatient pulmonary rehabilitation program. Each pair of exercise tests consisted of a test performed with room air and a second test performed with 50% supplemental oxygen, in random order. The primary outcome was the difference in exercise duration between tests performed with supplemental oxygen and with room air. This difference was compared before and after participation in a pulmonary rehabilitation program.RESULTS: Supplemental oxygen therapy improved exercise duration by 75 s before participation in a pulmonary rehabilitation program and by 153 s following pulmonary rehabilitation. Rehabilitation alone improved exercise duration by 28 s, but rehabilitation appeared to augment the exercise benefits of supplemental oxygen therapy by a mean of 78 s (95% CI 11 s to 145 s; P=0.03).CONCLUSION: The effects of supplemental oxygen therapy were augmented after pulmonary rehabilitation. The improvement in exercise duration with supplemental oxygen following rehabilitation was greater than either supplemental oxygen or pulmonary rehabilitation alone.