Exercise performance and symptoms in lowlanders with COPD ascending to moderate altitude: randomized trial

Objective: To evaluate the effects of altitude travel on exercise performance and symptoms in lowlanders with COPD. Design: Randomized crossover trial. Setting: University Hospital Zurich (490 m), research facility in mountain villages, Davos Clavadel (1,650 m) and Davos Jakobshorn (2,590 m). Participants: Forty COPD patients, Global Initiative for Obstructive Lung Disease (GOLD) grade 2-3, living below 800 m, median (quartiles) age 67 y (60; 69), forced expiratory volume in 1 second 57% predicted (49; 70). Intervention: Two-day sojourns at 490 m, 1,650 m, and 2,590 m in randomized order. Outcome measures: Six-minute walk distance (6MWD), cardiopulmonary exercise tests, symptoms, and other health effects. Results: At 490 m, days 1 and 2, median (quartiles) 6MWD were 558 m (477; 587) and 577 m (531; 629). At 2,590 m, days 1 and 2, mean changes in 6MWD from corresponding day at 490 m were -41 m (95% CI -51 to -31) and -40 m (-53 to -27), n=40, <0.05, both changes. At 1,650 m, day 1, 6MWD had changed by -22 m (-32 to -13), maximal oxygen uptake during bicycle exercise by -7% (-13 to 0) vs 490 m, <0.05, both changes. At 490 m, 1,650 m, and 2,590 m, day 1, resting PaO were 9.0 (8.4; 9.4), 8.1 (7.5; 8.6), and 6.8 (6.3; 7.4) kPa, respectively,