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Physiological Risk Factors of Severe High Altitude Illness: A Prospective Cohort Study.
MedLine Citation:
PMID:  22071330     Owner:  NLM     Status:  Publisher    
RATIONALE: An increasing number of persons, exposed to high altitude for leisure, sport or work, may suffer from severe high altitude illness. OBJECTIVES: To assess, in a large cohort of subjects, the association between physiological parameters and the risk of altitude illness and their discrimination ability in a risk prediction model. METHODS: 1326 persons went through a hypoxic exercise test before a sojourn above 4,000m. They were then followed up at high altitude and classified as suffering from severe high altitude illness (SHAI) or not. Analysis was stratified according to acetazolamide use. MEASUREMENTS AND MAIN RESULTS: Severe acute mountain sickness occurred in 314 (23.7%), high altitude pulmonary edema in 22 (1.7%) and high altitude cerebral edema in 13 (0.98%) patients. Among non acetazolamide users (n=917), main factors independently associated with SHAI were previous history of SHAI (adjusted Odds Ratios - aOR=12.82; 95%CI:6.95-23.66; P<0.001), ascent > 400m/day (aOR= 5.89; 95%CI:3.78-9.16; P<0.001), history of migraine (aOR= 2.28; 95%CI:1.28-4.07; P= 0.005), ventilatory response to hypoxia at exercise <0.78 L/min/kg (aOR=6.68; 95% CI:3.83-11.63; P<0.001) and desaturation at exercise in hypoxia ≥22% (aOR= 2.50; 95% CI:1.52-4.11;P<0.001). Last two parameters improved substantially the discrimination ability of multivariate prediction model (C-statistic rose from 0.81 to 0.88, P<0.001). Preventive use of acetazolamide reduced the relative risk of SHAI by 44%. CONCLUSIONS: In a large population of altitude visitors, chemosensitivity parameters (high desaturation and low ventilatory response to hypoxia at exercise) were independent predictors of severe high altitude illness. They improved the discrimination ability of a risk prediction model.
Jean-Paul Richalet; Philippe Larmignat; Eric Poitrine; Murielle Letournel; Florence Canouï-Poitrine
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-10-27
Journal Detail:
Title:  American journal of respiratory and critical care medicine     Volume:  -     ISSN:  1535-4970     ISO Abbreviation:  -     Publication Date:  2011 Oct 
Date Detail:
Created Date:  2011-11-10     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9421642     Medline TA:  Am J Respir Crit Care Med     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Dpt of Physiology, University Paris 13, 74 rue Marcel Cachin, Bobigny, 93017, France.
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