title: Physiological and psychological illness symptoms at high altitude and their relationship with acute mountain sickness: a prospective cohort study.
abstract: BACKGROUND
  The aim of this prospective observational cohort study was to investigate relationships between acute mountain sickness (AMS) and physical and mental health during a high altitude expedition.
  
  
  METHODS
  Forty-four participants (mean age, 34 ± 13 y; body mass index, 23.6 ± 3.5 kg·m(2) ; 57% male) completed the Dhaulagiri base camp trek in Nepal, a 19-day expedition attaining 5,372 m. Participants self-reported the following daily physical and mental health: AMS (defined by Lake Louise diagnosis and individual and total symptom scores), upper respiratory symptoms, diarrhea, and anxiety, plus physiological and behavioral factors.
  
  
  RESULTS
  The rate of Lake Louise-defined AMS per 100 person days was 9.2 (95% CI: 7.2-11.7). All investigated illnesses except diarrhea increased with altitude (all p < 0.001 by analysis of variance). Total AMS symptom score was associated with a lower arterial oxygen saturation, higher resting heart rate, more upper respiratory and diarrhea symptoms, greater anxiety, and lower fluid intake (all p < 0.02 by longitudinal multiple regression analyses). However, only upper respiratory symptoms, heart rate, arterial oxygen saturation, and fluid intake predicted future AMS symptoms [eg, an increase in upper respiratory symptoms by 5 units predicted an increase in the following day's AMS total symptom score by 0.72 units (0.54-0.89)].
  
  
  CONCLUSIONS
  Upper respiratory symptoms and anxiety increasingly contributed to symptom burden as altitude was gained. Data were consistent with increased heart rate, decreased arterial oxygen saturation, reduced fluid intake, and upper respiratory symptoms being causally associated with AMS. Upper respiratory symptoms and fluid intake are the simplest targets for intervention to reduce AMS during high altitude exposure.
authors: Extremes Research Group, School of Sport, Health and Exercise Sciences, Bangor University, Bangor, Gwynedd, UK.
authors: Samuel J
authors: SJ
authors: Oliver
authors: Stephan J
authors: SJ
authors: Sanders
authors: Catherine J
authors: CJ
authors: Williams
authors: Zoe A
authors: ZA
authors: Smith
authors: Emma
authors: E
authors: Lloyd-Davies
authors: Ross
authors: R
authors: Roberts
authors: Calum
authors: C
authors: Arthur
authors: Lew
authors: L
authors: Hardy
authors: Jamie H
authors: JH
authors: Macdonald
mesh_terms: D000208:Acute Disease; D000328:Adult; D000531:Altitude; D000532:Altitude Sickness / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology; D001007:Anxiety / Q000150:complications*; D015331:Cohort Studies; D003967:Diarrhea / Q000150:complications; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008603:Mental Health; D009390:Nepal; D010100:Oxygen / Q000097:blood; D011446:Prospective Studies; D012044:Regression Analysis; D012140:Respiratory Tract Diseases / Q000150:complications*
chemical_list: D010100:Oxygen