Sleep apnea and oxygen saturation in adults at 2640 m above sea level()

PURPOSE: To describe the SpO(2) in wakefulness, sleep and during the apnea–hypopnea in adults living in Bogotá, located at 2640 m above sea level. METHODS: Descriptive observational study in adults referred for polysomnogram (PSG). A normal Apnea hypopnea index (AHI) was defined as ≤5 and obstructive sleep apnea (OSA) was classified as mild (AHI 5–15), moderate (AHI 15–30), and severe (AHI >30). T-test or ANOVA test for SpO(2) differences between groups was used. RESULTS: 1799 patients, 33% women. 222 (12.8%) did not have OSA (normal IAH), 268 (14.9%) mild OSA, 315 (17.5%) moderate ,and 993 (55.2%) severe. In all cases a low SpO(2) (SpO(2)<90%) was found. The SpO(2) was lower when the AHI was higher, in wakefulness, in non-REM and in REM (p<0.001). For all grades of severity, SpO(2) decreased significantly from wakefulness to non-REM sleep and to REM sleep (p<0.001). Patients with severe OSA had higher desaturation during wakefulness (85.2±6.6%), non-REM sleep (83.1±7.7%), REM sleep (78.8±10.2), and during events (75.1±9.1%). CONCLUSIONS: Patients with OSA at 2640 m have nocturnal desaturation lower than 88%, which decreases with higher severity of OSA. The clinical impact of sleep disorders at this point may be greater than at sea level and should be studied.