title: Acute Mountain Sickness Symptoms Depend on Normobaric versus Hypobaric Hypoxia.
abstract: Acute mountain sickness (AMS), characterized by headache, nausea, fatigue, and dizziness when unacclimatized individuals rapidly ascend to high altitude, is exacerbated by exercise and can be disabling. Although AMS is observed in both normobaric (NH) and hypobaric hypoxia (HH), recent evidence suggests that NH and HH produce different physiological responses. We evaluated whether AMS symptoms were different in NH and HH during the initial stages of exposure and if the assessment tool mattered. Seventy-two 8 h exposures to normobaric normoxia (NN), NH, or HH were experienced by 36 subjects. The Environmental Symptoms Questionnaire (ESQ) and Lake Louise Self-report (LLS) were administered, resulting in a total of 360 assessments, with each subject answering the questionnaire 5 times during each of their 2 exposure days. Classification tree analysis indicated that symptoms contributing most to AMS were different in NH (namely, feeling sick and shortness of breath) compared to HH (characterized most by feeling faint, appetite loss, light headedness, and dim vision). However, the differences were not detected using the LLS. These results suggest that during the initial hours of exposure (1) AMS in HH may be a qualitatively different experience than in NH and (2) NH and HH may not be interchangeable environments.
authors.affiliation: Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA.
authors.forename: Dana M
authors.identifier: 0000-0002-3092-1367
authors.initials: DM
authors.lastname: DiPasquale
authors.affiliation: Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA.
authors.forename: Gary E
authors.initials: GE
authors.lastname: Strangman
authors.affiliation: Division of Wilderness Medicine, Department of Emergency Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: N Stuart
authors.initials: NS
authors.lastname: Harris
authors.affiliation: Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, MA, USA.
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Muza
mesh_terms: D000208:Acute Disease; D000328:Adult; D000531:Altitude; D000532:Altitude Sickness / Q000503:physiopathology*; D000818:Animals; D001066:Appetite / Q000502:physiology; D004417:Dyspnea / Q000503:physiopathology; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D011795:Surveys and Questionnaires; D055815:Young Adult