PT  - JOURNAL ARTICLE
AU  - Yvonne Nussbaumer-Ochsner
AU  - Nicole Schuepfer
AU  - Silvia Ulrich
AU  - Konrad E Bloch
TI  - Exacerbation of sleep apnoea by frequent central events in patients with the obstructive sleep apnoea syndrome at altitude: a randomised trial
AID  - 10.1136/thx.2009.125849
DP  - 2010 May 01
TA  - Thorax
PG  - 429--435
VI  - 65
IP  - 5
4099  - http://thorax.bmj.com/content/65/5/429.short
4100  - http://thorax.bmj.com/content/65/5/429.full
SO  - Thorax2010 May 01; 65
AB  - Background Many patients with the obstructive sleep apnoea syndrome (OSA) travel to the mountains for recreational and professional activities while temporarily discontinuing continuous positive airway pressure (CPAP) treatment. A study was undertaken to evaluate the hypothesis that altitude would aggravate their hypoxaemia, sleep-related breathing disturbances and impair daytime performance.Methods Thirty-four patients with OSA of median age 62 years (IQR 57–65), median apnoea/hypopnoea index (AHI) 47.5 events/h (IQR 32.4–72.8), residing at <600 m were enrolled. A crossover trial randomised for the sequence of altitude exposure was carried out: patients spent 1 day in Zurich (490 m) and 4 days in the Swiss Alps at 1860 m and 2590 m (2 days each) during which continuous positive airway pressure was discontinued. Daily evaluations included polysomnography, symptom questionnaires, physical examination and driving simulator tests.Results Polysomnography revealed median oxygen saturations at 490 m and in the first and second nights at 1860 and 2590 m, respectively, of 94%, 90%, 90%, 86% and 87% (p<0.01 between altitudes). Corresponding median AHI were 47.5, 85.1, 74.6, 90.0 and 90.9 events/h (p<0.01 between altitudes) with ratios of central to obstructive events of 0.1, 0.8, 1.0, 1.9 and 1.9 (p<0.01 between altitudes). Tracking performance during simulated driving was significantly impaired at 2590 m compared with 490 m. Systolic blood pressure and cardiac arrhythmias were increased at altitude.Conclusions Altitude exposure in untreated patients with OSA aggravates hypoxaemia, increases sleep-related breathing disturbances due to frequent central apnoeas/hypopnoeas, impairs driving simulator performance and induces cardiovascular stress. These findings have implications for counselling and treating patients with OSA planning to travel to high altitude.ClinicalTrials.gov identifier NCT00514826.