The effect of long-acting dual bronchodilator therapy on exercise tolerance, dynamic hyperinflation, and dead space during constant work rate exercise in COPD
William W. Stringer, János Pórszász, Min Cao, Harry B. Rossiter, Shahid Siddiqui, Stephen I. Rennard, Richard Casaburi
Abstract
This study was a randomized clinical trial (NCT03081156) that collected detailed physiology data to investigate the effect of dual bronchodilator therapy on exercise tolerance in COPD, and additionally to determine the relative contributions of changes in dead space ventilation (V D /V T ) and dynamic hyperinflation to alterations in exercise limitation. We utilized a unique noninvasive method to assess V D /V T (transcutaneous carbon dioxide, Tc[Formula: see text]) and found that dual bronchodilators yielded a moderate improvement in exercise tolerance. Importantly, attenuation of dynamic hyperinflation rather than change in dead space ventilation was the most important contributor to exercise tolerance improvement.