Body Temperature, Autonomic Responses, and Acute Mountain Sickness

A few studies have reported increased body temperature (To) associated with acute mountain sickness (AMS), but these usually include exercise, varying environmental conditions over days, and pulmonary edema. We wished to determine whether To would increase with AMS during early exposure to simulated altitude at rest. Ninety-four exposures of 51 men and women to reduced PB (423 mmHg = 16,000 ft = 4850 m) were carried out for 8 to 12 h. AMS was evaluated by LL and AMS-C scores near end of exposure, and To was measured by oral digital thermometer before altitude and after 1 (A1), 6 (A6), and last (A12) h at simulated altitude. Other measurements included ventilation, O2 consumption and autonomic indicators of plasma catecholamines, HR, and HR variability. Average To increased by 0.5°F from A1 to A12 in all subjects (p < 0.001). Comparison between 16 subjects with lowest AMS scores (mean LL = 1.0, range = 0 to 2.5) and 16 other subjects with highest AMS scores (mean LL = 7.4, range = 5 to 11) demonstrated a t...