0492 Variability in High Altitude Sleep Disordered Breathing and Impact of Acclimatization

Abstract Introduction Individuals who travel to high altitude experience variable levels of poor sleep quality and sleep disordered breathing, which can have neurocognitive and other systemic impacts. Past studies by our group and others have shown that the apnea hypopnea index (AHI) increases, and nocturnal oxygen saturation decreases at higher altitude. This may change over time with acclimatization to environmental hypoxemia. The aim of this study was to examine the trajectory and variability in high altitude sleep disordered breathing effects in healthy young adult volunteers. Methods Twenty healthy volunteers were recruited from a local university (35% women), mean age 23.5(20.0, 32.2) years and BMI of 30.0(28.0, 35.9) kg/m2. Peripheral Arterial tonometry based home sleep apnea tests (HSAT; WatchPat One) was performed on all subjects at sea level up to three days prior to transportation via car to high altitude (3800m White Mountain Research Center - Barcroft Station, CA). Participants continued HSAT testing for three consecutive nights at high altitude sleeping in any position, without oxygen, acetazolamide, or use of any other medications impacting sleep or breathing. Mixed effects modeling was used to compare sleep parameters across nights. Results Subjects' characteristics: median (IQR)[range] age 23(20,32)[19,39] years, BMI 30(28, 36)[23,48] kg/m2, 35% women. AHI at altitude night 1 (67±4 events/hour) was significantly higher than sea level (7±4 events/hour; P< 0.001). Mean sleep SpO2 at altitude night 1 (79±1%) was significantly lower than sea level (95±1%; P< 0.0001). There was no statistically significant change in AHI or mean sleep SpO2 on nights 1-3; however substantial variability was noted between individual trajectories. Conclusion Healthy young adults exhibit severe Sleep Disordered Breathing when traveling to high altitude. Despite acclimatization, the severity of Sleep Disordered Breathing remained relatively unchanged overall. However substantial differences in individual trajectories were apparent. Larger studies are needed to understand how differences in genetics, sex, and other factors might impact Sleep Disordered Breathing at altitude. In addition, the impacts of (or tolerances to) altitude are likely to be broadly informative towards Sleep Disordered Breathing, hypoxemia, and other areas. Support (if any) N/A