IMPORTANCE There are no established measures to prevent nocturnal breathing disturbances and other altitude-related adverse health effects (ARAHEs) among lowlanders with chronic obstructive pulmonary disease (COPD) traveling to high altitude. OBJECTIVE To evaluate whether nocturnal oxygen therapy (NOT) prevents nocturnal hypoxemia and breathing disturbances during the first night of a stay at 2048 m and reduces the incidence of ARAHEs. DESIGN, SETTING, AND PARTICIPANTS This randomized, placebo-controlled crossover trial was performed from January to October 2014 with 32 patients with COPD living below 800 m with forced expiratory volume in the first second of expiration (FEV 1) between 30% and 80% predicted, pulse oximetry of at least 92%, not requiring oxygen therapy, and without history of sleep apnea. Evaluations were performed at the University Hospital Zurich (490 m, baseline) and during 2 stays of 2 days and nights each in a Swiss Alpine hotel at 2048 m while NOT or placebo treatment was administered in a randomized order. Between altitude sojourns, patients spent at least 2 weeks

This case-control study evaluates a possible association between high altitude pulmonary hypertension (HAPH) and sleep apnoea in people living at high altitude.Ninety highlanders living at altitudes >2500 m without excessive erythrocytosis and with normal spirometry were studied at 3250 m (Aksay, Kyrgyzstan); 34 healthy lowlanders living below 800 m were studied at 760 m (Bishkek, Kyrgyzstan). Echocardiography, polysomnography and other outcomes were assessed. Thirty-six highlanders with elevated mean pulmonary artery pressure (mPAP) >30 mmHg (31-42 mmHg by echocardiography) were designated as HAPH+. Their data were compared to that of 54 healthy highlanders (HH, mPAP 13-28 mmHg) and 34 healthy lowlanders (LL, mPAP 8-24 mmHg).The HAPH+ group (median age 52 years (interquartile range 47-59) had a higher apnoea-hypopnoea index (AHI) of 33.8 events·h (26.9-54.6) and spent a greater percentage of the night-time with an oxygen saturation <90% (T<90; 78% (61-89)) than the HH group (median age 39 years (32-48), AHI 9.0 events·h (3.6-16), T<90 33% (10-69)) and the LL group (median age 40 years (30-47), AHI 4.3 events·h (1.4-12.6), T<90 0% (0-0)); p<0.007 for AHI and T<90, respectively, in HAPH+ versus others. In highlanders, multivariable regression analysis confirmed an independent association between mPAP and both AHI and T<90, when controlled for age, gender and body mass index.Pulmonary hypertension in highlanders is associated with sleep apnoea and hypoxaemia even when adjusted for age, gender and body mass index, suggesting pathophysiologic interactions between pulmonary haemodynamics and sleep apnoea.

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Key Points Question Does preventive dexamethasone treatment mitigate altitude-related nocturnal hypoxemia in lowlanders with chronic obstructive pulmonary disease traveling to a high altitude? Findings In this randomized clinical trial of 118 patients with chronic obstructive pulmonary disease who lived below 800 m, dexamethasone, 4 mg, orally twice daily, starting 24 hours before ascent and while staying in a clinic at 3100 m, significantly mitigated the altitude-induced decrease in mean arterial oxygen saturation during 2 nights at 3100 m by 2% to 3%. In addition, dexamethasone therapy prevented emergence of central sleep apnea and improved subjective sleep quality. Meaning Patients with chronic obstructive pulmonary disease traveling to a high altitude may benefit from preventive dexamethasone treatment in terms of nocturnal oxygenation and sleep quality.