TY - JOUR T1 - Predictors of improvement in peak exercise capacity with helium-hyperoxia in severely-impaired COPD patients under long-term oxygen therapy JF - European Respiratory Journal JO - Eur Respir J VL - 38 IS - Suppl 55 SP - 1712 AU - Marcos Nunes AU - Fernando Queiroga-Jr. AU - Ethiane Meda AU - Gaspar Chiappa AU - Maria-Christina Machado AU - Luiz Eduardo Nery AU - J. Alberto Neder Y1 - 2011/09/01 UR - http://erj.ersjournals.com/content/38/Suppl_55/1712.abstract N2 - Heliox can improve exercise tolerance in ventilatory-limited patients with chronic obstructive pulmonary disease (COPD). Unfortunately, however, these benefits are quite heterogeneous in patients with similar levels of resting airflow obstruction. In order to gain further insight into the determinants of such variability in hypoxaemic patients with advanced COPD, we evaluated 24 males (GOLD stage IV) who were under long-term O2 therapy. Patients underwent maximum incremental cardiopulmonary exercise tests while breathing hyperoxia (HiOX= 40% O2) or helium-hyperoxia (He-HiOX= 60% He/40%O2). Peak work rate (WR) was significantly improved with He-HiOX compared to HiOX (54±26 W vs. 48±23 W). This was associated with increased mean ins and expiratory flows and larger tidal volumes; in addition, end-expiratory lung volume was lower at peak exercise (5.57±1.12 L vs 5.65±1.13 L; p<0.05). Δ(He-HiOX – HiOX) WR was positively related to markers of lung hyperinflation including total lung capacity and residual volume (r= 0.52 and r= 0.40; p<0.05). Interestingly, however, fat-free mass (FFM) also showed to be strongly related to ΔWR; in fact, FFM was the only independent predictor of ΔWR on a multiple regression analysis (r2= 0.66; p<0.001). We conclude that once patients with advanced COPD are relieved from the “central” ventilatory constraints by breathing hyperoxic heliox, appendicular muscle mass becomes an important determinant of maxinal exercise capacity. These data lend support to the notion that preserved muscle mass is important for improved respiratory mechanics be translated into enhamced peak exercise capacity in these patients. ER -