This is a randomized, placebo-controlled, double-blind parallel trial evaluating the effect of acetazolamide (375 mg per day) vs. placebo on sleep related breathing disturbances in lowlanders with chronic obstructive pulmonary disease travelling to altitude. Participants living in the Bishkek area, Kyrgyzstan (760m), will be transferred by car within 4h to the Tuja Ashu high altitude clinic (3200 m), and stay there for 2 days. Acetazolamide 375mg/day (or placebo), will be administered 24 hours before departure at 760 m and during the stay at altitude. Outcomes will be assessed during the stay at 3200 m.~Sleep related breathing disturbances will be evaluated by respiratory polygraphy.~An interim analysis will be carried out when 90 patients will have completed the study or after the first year. The Peto's method will be used to correct the P-values.
In this trial, the investigators will evaluate the effect of acetazolamide (375 mg per day) vs. placebo on sleep related breathing disturbances at altitude in patients with COPD.