Effect of Acetazolamide and AutoCPAP Therapy on Breathing Disturbances Among Patients With Obstructive Sleep Apnea Syndrome Who Travel to Altitude: A Randomized Controlled Trial

Study Questions:

What is the impact of acetazolamide and autoadjusted continuous positive airway pressure (autoCPAP) on sleep-related breathing disturbances among patients with obstructive sleep apnea (OSA) traveling to higher altitudes?


This was a randomized, placebo-controlled, double-blind, crossover trial of 51 predominantly male patients with OSA living below an altitude of 800 m and receiving therapy with CPAP. Patients were studied at moderately high altitudes in the Swiss Alps (for 2 days at 1630 m and 1 day at 2590 m, separated by a 2-week washout period at <800 m). During these study periods at higher altitude, patients either took acetazolamide (750 mg/d) or placebo in addition to autoCPAP. Primary outcomes were nocturnal oxygen saturation and the apnea/hypopnea index (AHI).


At moderately high altitudes, the combination of acetazolamide and autoCPAP, when compared with placebo and autoCPAP, increased the median nocturnal oxygen saturation by 1.0% (95% confidence interval [CI], 0.3%-1.0%) at 1630 m and by 2.0% (95% CI, 2.0-2.0%) at 2590 m. The corresponding median reduction in the AHI was 3.2/hour (95% CI, 1.3/h-7.5/h) at 1630 m and 9.2/hour (95% CI, 5.1/h-14.6/h) at 2590 m.


The combination of acetazolamide and autoCPAP therapy, when compared to autoCPAP alone, modestly improved nocturnal oxygenation and sleep-disordered breathing among patients with established OSA traveling to moderately high altitudes.


With proven deleterious consequences and a prevalence of 2-4% among some Western populations, OSA demands attention in the cardiology community. This trial demonstrated that combined therapy with acetazolamide and autoCPAP improved sleep-disordered breathing and oxygenation among OSA patients traveling to higher altitudes. AutoCPAP, enhanced by acetazolamide, may certainly have a role to play in this growing population.

Clinical Topics: Heart Failure and Cardiomyopathies, Sleep Apnea

Keywords: Cross-Over Studies, Polysomnography, Continuous Positive Airway Pressure, Confidence Intervals, Oxygen, Respiration, Sleep Apnea Syndromes

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