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Wilderness Environ Med. 2011 Dec;22(4):316-20. doi: 10.1016/j.wem.2011.07.002. Epub 2011 Oct 7.

Improving sleep at altitude: a comparison of therapies.

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University of Utah College of Nursing and School of Medicine, Salt Lake City, UT 84112, USA.



This study aimed to compare 3 treatment modalities during sleep at an altitude of 5300 m to identify strategies for reducing the incidence of periodic breathing at high altitude.


Fifteen trekkers, with identical ascent profiles and no signs or symptoms of altitude illness, served as subjects. All study participants arrived at 5300 m after a gradual ascent from 1300 m. On their second night at 5300 m, subjects were randomly assigned (with a computer-based random assignment procedure) to 1 of 4 different treatment groups: control (n = 4); 1 L/min O(2) via a demand system during sleep (n = 3); 1 L/min O(2)/CO(2) mix (1.5% CO(2)) via a demand system during sleep (n = 4); or 125 mg acetazolamide 30 minutes before bedtime (n = 4). Heart rate, respiration rate, blood oxygen saturation, tidal volume, minute volume, and apnea hypopnea index were measured.


Upon comparing the 4 groups, there were no statistically significant differences between the variables. One-way analysis of variance indicated a trend toward statistical significance for SaO(2) between groups (F = 2.9, P = .08), and Tukey Honestly Significant Difference (HSD) post hoc tests indicated a trend in the SaO(2) difference between the 1 L/min oxygen and control groups (P = .07). While 1-way analysis of variance suggested no difference for respiratory rate between groups (F = 2.5, P = .1), Tukey HSD indicated a trend in statistical difference of the respiratory rate between 1 L/min O(2) and 1 L/min O(2)/CO(2) mixture (P = .08).


These statistical trends found between control and treatment groups indicate that further study is warranted.

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