ACUTE MOUNTAIN-SICKNESS - IS THERE A LAG PERIOD BEFORE SYMPTOMS

The present study was designed to determine if symptoms of acute mount ain sickness are presented within six hours after arrival at high alti tude. Seventeen male subjects, 23-30 years, were studied. The subjects were professional soccer players, life-long residents at low altitude s except one player who was playing soccer in a team at 3400 m (512 mm Hg of Barometric Pressure) during an entire year in 1995. The players were transported by a commercial airline from Lima (150 m) to Cusco ( 3400 m). The trip lasted 1 hour. Heart rate and arterial oxygen satura tion were measured at rest in Lima (150 m), at the time of arrival at Cusco, and at 4 and 6 hours after arrival at 3400 m. On day 6 at high altitude, the physical performance during a soccer game was assessed. The symptoms of acute mountain sickness (AMS) were assessed 6 hours af ter arrival at Cusco with a self-administered questionnaire, and there after each 24-hours up to 5 days of exposure to high altitude. The fol lowing symptoms were assessed: headache, gastrointestinal symptoms, di zziness, fatigue, and sleep abnormalities. AMS was defined by a Lake-L ouise score greater than or equal to 4 (self-assessment only). Thirty five percent of the soccer players developed AMS within 6 hours after arrival by air at 3400 m altitude. Arterial oxygen saturation at arriv al was higher in those player who developed AMS within 6 hours after a rrival (94.3 +/- 0.94% vs 90.8 +/- 2.36; P < 0.001). From arrival to 6 hours of exposure to altitude, there was a significant fall in arteri al oxygen saturation in those men who developed AMS than in those who did not. Results from the stepwise multiple regression (R-2 = 0.59; P < 0.04) and logistic regression (R-2 = 0.48; P < 0.0019) analyses show ed that the difference between arterial oxygen saturation at sea level and at arrival at Cusco was a predictor for the development of AMS wi thin 6 hours upon arrival at altitude. This suggests that the lower th e difference between arterial oxygen saturation at sea level and at ar rival, the higher the probability to develop AMS within 6 hours after arrival at 3400 m. The presentation of AMS, however, does not predict low performance in physical activity at high altitude. (C) 1998 Wiley- Liss, Inc.