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Updated: Jan 16, 2026
A Model to Simulate Clinically Relevant Hypoxia in Humans
Published on: December 22, 2016
Nocturnal cerebral oxygenation in patients with COPD at altitude: data from a randomized clinical trial of
Yaël A Schmuziger1, Maamed Mademilov2,3, Aline Buergin1
1Department of Respiratory Medicine, University Hospital of Zurich, Zurich, Switzerland.
Study Objectives:
Patients with chronic obstructive pulmonary disease may experience cerebral tissue deoxygenation during altitude travel, especially during sleep. We quantified nocturnal cerebral (CTO) and arterial oxygenation (SpO2) in patients with chronic obstructive pulmonary disease during a stay at 3,100 m and evaluated the effects of preventive acetazolamide therapy.
Methods:
Patients with moderate-to-severe chronic obstructive pulmonary disease, living at an altitude < 800 m, underwent nocturnal pulse oximetry and cerebral tissue oximetry by near-infrared spectroscopy at 760 m and during the first night at 3,100 m. Patients were randomized to 375 mg/d acetazolamide or placebo starting 24 hours before ascent and while staying at 3,100 m. Altitude and acetazolamide effects on CTO and other outcomes were evaluated by mixed linear regression analysis.
Results:
Fifty-two patients, 9 female, mean ± standard deviation age 55.4 ± 8.9 years, forced expiratory volume in 1 second 60 ± 13% predicted, were included in the analyses. When ascending from 760 to 3,100 m, in those taking placebo (n = 17) CTO and SpO2 decreased from 66.5 ± 1.0% to 63.4 ± 1.0% (P < .05) and from 90.8 ± 0.4% to 83.7 ± 0.4% (P < .05), respectively; cerebral and arterial oxygen desaturation indices (≥ 4% dips in CTO or SpO2, respectively) increased by a mean (95% confidence interval) of 6.2/h (4.0-8.5) and 19.5/h (13.2-25.9) (P < .05). Compared to placebo, the mean CTO (+2.3% [2.2-2.5]) and SpO2 (+2.1% [2.1-2.2]) were higher and the mean cerebral oxygen desaturation index (-4.4/h [-7.3 to -1.5]) and arterial oxygen desaturation index (-15.0/h [-23.1 to -6.9]) were lower in the acetazolamide group (P < .05 all effects).
Conclusions:
Patients with chronic obstructive pulmonary disease traveling to 3,100 m experienced sustained and intermittent nocturnal cerebral deoxygenation related to hypoxemia. Acetazolamide mitigated these altitude-related deoxygenations, albeit not to lowland values.
Clinical Trial Registration:
Registry: ClinicalTrials.gov; Name: Effect Of Acetazolamide On Altitude Related Illness In Patients With Respiratory Disease; URL: https://clinicaltrials.gov/study/NCT03156231; Identifier: NCT03156231.
Citation:
Schmuziger YA, Mademilov M, Buergin A, et al. Nocturnal cerebral oxygenation in patients with COPD at altitude: data from a randomized clinical trial of acetazolamide. J Clin Sleep Med. 2025;21(12):2051-2061.
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