Exacerbation of sleep apnoea by frequent central events in patients with the obstructive sleep apnoea syndrome at altitude: a randomised trial

Abstract

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 57e65), median apnoea/hypopnoea index (AHI) 47.5 events/h (IQR 32.4e72.8), 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 sleeprelated 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.

Effects of Positive Airway Pressure on Patients with Obstructive Sleep Apnea during Acute Ascent to Altitude

“…Our study demonstrated similar findings, but our participants who experienced altitude without PAP had less development of central apnea events than in previous studies, perhaps in part due to the administration of supplemental oxygen (4,7). Participants in the Burgess study ORIGINAL RESEARCH were exposed to simulated altitude over a 4-hour period before the 8-hour sleep study, to allow for greater hypoxic stimulus.…”

“…The partial pressure of oxygen of inspired air (PI O 2 ) decreases and hypoxemia increases with ascent (2,5,6). Altitude exposure in untreated patients with OSA worsens hypoxemia and increases sleep-related breathing disturbances due to frequent central apnea or hypopnea (7). One of the key physiological traits of sleep apnea is the presence of a hypersensitive ventilatory control system (high loop gain), characterized by a large ventilatory response to a change in ventilation.…”

Effect of Moderate Elevation above Sea Level on Blood Oxygen Saturation in Healthy Young Adults

“…Since acclimatization duration has an important impact on Sp O 2 at a defined altitude [16,17,18], it was important that the recruited volunteers were residents of the college where they were studying, which was the case with each participant of this study. In both institutions, an air conditioning unit maintained the ambient temperature in the room at 23–25°C.…”

High Altitude, Continuous Positive Airway Pressure, and Obstructive Sleep Apnea: Subjective Observations and Objective Data

“…Another recent study 7 assessed the effects of increased altitude from baseline 490 m, with 2 nights each at 1860 m and 2590 m. Although there was a reduction in nocturnal oxygen saturation (94%, 90%, 86-87%, respectively), all patients ascended to altitude without CPAP, despite being CPAP dependant at baseline. In our report we assessed the longitudinal effects of acute changes in altitude from 820 m to 4400 m on CPAP levels and apneic/hypopneic episodes, while continuing to use CPAP.…”