Hypoxemia and acute mountain sickness: which comes first?

Abstract Loeppky, Jack A., Milton V. Icenogle, Gerald A. Charlton, Carole A. Conn, Damon Maes, Katrina Riboni, Lee Gates, Marcos F. Vidal Melo, and Robert A. Roach. Hypoxia and AMS: which comes first? High Alt. Med. Biol. 9:271–279, 2008.—Hypoxemia is usually associated with acute mountain sickness (AMS), but most studies have varied in time and magnitude of altitude exposure, exercise, diet, environmental conditions, and severity of pulmonary edema. We wished to determine whether hypoxemia occurred early in subjects who developed subsequent AMS while resting at a simulated altitude of 426 mmHg (≈16,000 ft or 4880 m). Exposures of 51 men and women were carried out for 8 to 12 h. AMS was determined by Lake Louise (LL) and AMS-C scores near the end of exposure, with spirometry and gas exchange measured the day before (C) and after 1 (A1), 6 (A6), and last (A12) h at simulated altitude and arterial blood at C, A1, and A12. Responses of 16 subjects having the lowest AMS scores (nonAMS: mean LL = 1.0, range = ...