Patients with obstructive sleep apnea syndrome benefit from acetazolamide during an altitude sojourn: A randomized, placebo-controlled, double-blind trial.

Author(s): Nussbaumer-Ochsner Y, Latshang TD, Ulrich S, Kohler M, Thurnheer R, Bloch KE

Affiliation(s): 1Sleep Disorders Center, Pulmonary Division, University Hospital of Zurich and Center for Human Integrative Physiology, University of Zurich, Zurich, Switzerland;

Publication date & source: 2011-06-09, Chest., [Epub ahead of print]

Abstract BACKGROUND: Many patients with obstructive sleep apnea syndrome (OSA) are unable or not willing to use CPAP therapy when traveling to the mountains for work or recreation although they risk pronounced hypoxemia and exacerbation of sleep apnea. Since the treatment of OSA at altitude has not been established we tested the hypothesis that acetazolamide improves hypoxemia, sleep and breathing disturbances in otherwise untreated OSA patients at altitude. METHODS: Forty-five OSA patients on long-term CPAP, median age 64y, living at <600m underwent a placebo-controlled, double-blind cross-over trial randomized for the sequence of drug and altitude exposure (490m, 1860m and 2590m). Patients spent two 3-day periods at altitude and a 2-week wash-out period at <600 m. At altitude, patients discontinued CPAP and received acetazolamide 2x250mg daily or placebo. Polysomnography, vigilance and symptoms were evaluated. RESULTS: At 490m, off CPAP, median nocturnal oxygen saturation was 93%, apnea/hypopnea index 51.2/h. On placebo at 1860m and 2590m, corresponding values were 89% and 85%, and 63.6/h and 86.2/h, respectively (P<0.01 vs. 490m, both instances). On acetazolamide at 1860m and 2590m, oxygen saturation was higher (91% and 88%) and apnea/hypopnea indices were lower (48.0/h and 61.4/h) than on placebo (P<0.01 all instances). Acetazolamide reduced nocturnal transcutaneous PCO(2), improved sleep efficiency and subjective insomnia and prevented excessive blood pressure elevations at altitude. CONCLUSIONS: In OSA patients discontinuing CPAP during an altitude sojourn, acetazolamide improves oxygenation, breathing disturbances and sleep quality by stimulating ventilation. Therefore, OSA patients may benefit from acetazolamide at altitude if CPAP therapy is not feasible. Trial registration: ClinicalTrials.gov NCT00714740.