Acute mountain sickness (AMS) affects 25% to 75% of the tens of millions of high altitude travelers annually. Major contributing factors to AMS are hypoxia and nocturnal desaturations. Small studies have found that positive end-expiratory pressure devices are able to prevent and ameliorate AMS, but there have been no controlled trials. The purpose of this study was to assess a single-use nasal strip, Theravent, that provided 5 cm H2o positive end-expiratory pressure (PEEP) while sleeping for the improvement of AMS and nocturnal hypoxic events.
Healthy, unacclimatized adult participants trekking in the Khumbu region of the Himalayas during Fall 2013 were randomly assigned to Theravent or to a visually identical sham device before their first night sleeping at 4280 m or 4358 m. The primary outcome was AMS incidence, measured by the Lake Louise Score questionnaire, with secondary outcomes of physiologic sleep indices measured by the WatchPAT-200 continuous sleep monitor.
Two hundred nineteen participants were included for intent-to-treat analysis, 115 received PEEP and 104 placebo, with no differences in demographic characteristics between groups. There was no decrease in AMS with the intervention (14% PEEP vs 17% placebo, P = .65, 95% CI: −7% to 14%). The PEEP group reported decreased headache (64% vs 76%, P = .047, OR 0.51, 95% CI: 0.27–0.95) and dizziness (81% vs 98%, P = .024, OR 0.29, 95% CI: 0.09–0.78). The PEEP group showed significant improvement in average oxygen saturation (Spo2 [80.4% vs 78.3%; P = .007, 95% CI: 0.58–3.63]), reduced rate of Spo2 below 80% (30.9% vs 46.1%; P = 0.022, 95% CI: 2.22–28.18), and a significant correlation between percentage of time in deep sleep and Spo2 (r = 0.22, 95% CI: 0.05–0.39).
Although Theravent had a high rate of user discomfort, this lightweight inexpensive PEEP device may improve some distressing symptoms of AMS and nocturnal oxygenation while sleeping at high altitude.
© 2014 Published by Elsevier Inc.