EFFECTS OF HIGH-ALTITUDE PERIODIC BREATHING ON SLEEP AND ARTERIAL OXYHEMOGLOBIN SATURATION

This study aimed to investigate the effect of periodic breathing (PB) at high altitude on sleep structure and arterial oxygen saturation (Sa ,O-2), Five healthy subjects underwent polysomnographic studies at sea level, and during the first and the fourth week of sojourn at 5,050 m . Their breathing pattern, sleep architecture and Sa,O-2 mere analysed . PB was detected in the high-altitude studies during nonrapid eye mov ement (NREM) sleep and tended to increase from the first to the fourth week. Stages 3-4 were absent in four subjects at the first week, but only in one at the fourth week, irrespective of the amount of PB, The arousal index was 11.6+/-3.8 at sea level, 30.1+/-15.5 at the first we ek at altitude and 33.0+/-18.2 at the fourth week, At altitude, arousa l index in NREM sleep was higher during PB than during regular breathi ng. In NREM sleep, the mean highest Sa,O-2 levels in NREM epochs with PB were higher than in those with regular breathing by 2.8+/-1.7% at t he first week and 2.9+/-1.5% at the fourth week (p<0.025). From the fi rst to the fourth week, mean Sa,O-2 increased significantly during wak efulness (5.6%), NREM (5.2% with regular breathing and 5.3% with PB) a nd rapid eye movement sleep (7.6%). The data demonstrate a slight role of periodic breathing in altering sleep architecture at high altitude and also show that periodic breathing induces only a minor improvemen t in arterial oxygen saturation during nonrapid eye movement sleep.