Exacerbation of sleep apnoea by frequent central events in patients with the obstructive sleep apnoea syndrome at altitude: a randomised trial.
Level 2 - randomized trial
Individual randomized crossover trial
PubMed 20435865 · doi:10.1136/thx.2009.125849
What was done
Thirty-four low-altitude residents with obstructive sleep apnea (OSA; median age 62 years, median baseline AHI 47.5 events/h) discontinued continuous positive airway pressure (CPAP) and underwent a randomized crossover trial evaluating altitude exposure. Participants were tested during 1 day at 490 m (Zurich) and 4 days in the Swiss Alps (2 days at 1860 m and 2 days at 2590 m). Outcomes included polysomnography, symptom questionnaires, physical examination, and driving simulator performance.
What was found
Median nocturnal oxygen saturation decreased from 94% at 490 m to 90% and 90% at 1860 m (nights 1 and 2), and to 86% and 87% at 2590 m (nights 1 and 2; p<0.01 between altitudes). Median AHI increased from 47.5 events/h at 490 m to 85.1 and 74.6 events/h at 1860 m, and 90.0 and 90.9 events/h at 2590 m (p<0.01). Central-to-obstructive event ratios increased from 0.1 at 490 m to 0.8 and 1.0 at 1860 m, and 1.9 at 2590 m (p<0.01). Simulated driving tracking performance was significantly impaired at 2590 m versus 490 m. Systolic blood pressure and cardiac arrhythmias were increased at altitude, though specific values were not reported in the abstract.
Why it matters
Discontinuing CPAP at moderate to high altitude substantially worsens hypoxemia and induces frequent central apneas in OSA patients, carrying immediate risks for driving safety and cardiovascular strain.
Limits
The sample size was small (n=34) and limited to patients with relatively severe baseline OSA. Stays at each altitude were short (2 days), so long-term acclimatization could not be assessed, and exact quantitative data for blood pressure, arrhythmias, and driving performance were omitted from the abstract.
Cited by
- supports High altitude significantly exacerbates sleep apnea and sleep-disordered breathing.