title: Postexercise peripheral oxygen saturation after completion of the 6-minute walk test predicts successfully reaching the summit of Aconcagua.
abstract: OBJECTIVE
  The 6-minute walk test (6MWT) is a single measurement of functional status in patients with cardiovascular disease. It has not been studied at high altitude. We investigate the screening value of 6-minute walk distance (6MWD) and postexercise vital sign (VS) measurements as predictors of successfully reaching the summit or development of acute mountain sickness (AMS) on Aconcagua (6962 m).
  
  
  METHODS
  Prospective observational cohort in Aconcagua Provincial Park, Argentina. Adults climbing the normal route who registered with base camp physicians were included. There were no exclusion criteria. VSs were measured before (resting) and after (postexercise) completion of 6MWT while volunteers acclimatized at Plaza de Mulas base camp (4365 m). Volunteers proceeded towards the summit at their own pace and upon descent returned a questionnaire with maximum altitude reached and Lake Louise AMS Self-report Score (LLSelf).
  
  
  RESULTS
  One hundred twenty-four volunteers completed the 6MWT. Sixty-four volunteers (51.6%) completed questionnaires; 56% summited. Median LLSelf was 4 (IQR: 3.0-6.5). There was no association between any resting or postexercise VS measurements and AMS. However, mean postexercise SpO(2) was 80.8% in summiters and 76.4% in nonsummiters, a difference of -4.4% (95% CI: -6.7 to -2.0, p = 0.0005). Postexercise SpO(2) < 75% had 97.2% sensitivity and negative likelihood ratio of 0.086 in predicting the outcome of successfully reaching the summit: only one climber with SpO(2) < 75% successfully reached the summit.
  
  
  CONCLUSIONS
  This study provides the first published data on 6MWD recorded in the field at high altitude. Postexercise SpO(2) < 75% may be a useful screening test for predicting the outcome of successfully reaching the summit of Aconcagua.
authors.affiliation: Department of Emergency Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA. matt.lazio@gmail.com
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Lazio
authors.forename: Jon D
authors.initials: JD
authors.lastname: Van Roo
authors.forename: Carlos
authors.initials: C
authors.lastname: Pesce
authors.forename: Sanjeev
authors.initials: S
authors.lastname: Malik
authors.forename: D Mark
authors.initials: DM
authors.lastname: Courtney
mesh_terms: D000064:Acclimatization; D000328:Adult; D000531:Altitude; D000532:Altitude Sickness / Q000517:prevention & control; D001118:Argentina; D001794:Blood Pressure; D005080:Exercise Test / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D009051:Mountaineering; D010100:Oxygen / Q000378:metabolism*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011795:Surveys and Questionnaires; D055986:Vital Signs; D016138:Walking
chemical_list: D010100:Oxygen