Effects of oxygen on exertional dyspnea and exercise performance in patients with COPD

Background: Accumulation of studying the oxygen (O 2 ) response in chronic obstructive pulmonary disease (COPD) should provide important clues to the pathophysiology of exertional dyspnea. We investigated the exercise responses of hyperoxia on the dyspnea profile, as well as cardio-pulmonary, acidotic and sympathetic parameters in 35 patients with stable COPD. Methods: The patients breathed 24% O 2 or compressed air (CA) in random order during two incremental cycle exercise tests. Results: The PaO 2 and PaCO 2 values were higher (P 2 compared with CA. At a standardized point in time near peak exercise, O 2 reduced plasma lactate (P Conclusion: Regardless of breathing CA or hyperoxia, COPD patients did not develop ventilatory compensation for the exertional acidosis to stop exercise, resulting in reaching a similar pH. During a standardized exercise phase, hyperoxia did not change the pattern of exertional dyspnea while breathing CA in these patients, although hyperoxia exerted miscellaneous effects.