title: Investigating carbon monoxide exposure on Denali.
abstract: OBJECTIVE
  This exploratory study assessed a potential relationship between elevated carboxyhemoglobin (COHb) levels and acute mountain sickness (AMS) at 4300 m on Denali. Additional analysis assessed the relationship among COHb levels, AMS, and climber characteristics and behaviors.
  
  
  METHODS
  Participants were screened for AMS with the Lake Louise Self-Report questionnaire and answered questions focusing on AMS symptoms, prevention, and previous altitude illness. Levels of COHb were measured by serum cooximetry. Additional questions assessed stove practices, climbing practices, and climber behaviors. Nonparametric statistical analyses were performed to examine potential relationships among COHb levels, AMS symptoms, and climber behaviors.
  
  
  RESULTS
  A total of 146 climbers participated in the study. Eighteen climbers (12.5%) were positive for carbon monoxide (CO) exposure and 20 (13.7%) met criteria for AMS. No significant relationship was observed between positive CO exposure and positive criteria for AMS. Climbers descending the mountain were 3.6 times more likely to meet the study criteria for positive CO exposure compared with those ascending the mountain (P = .42). In addition, COHb levels were significantly higher for those descending the mountain (P = .012) and for those taking prophylactic medications (P = .010). Climbers meeting positive criteria for AMS operated their stoves significantly longer (P = .047).
  
  
  CONCLUSIONS
  No significant relationship between AMS symptoms and CO exposure was observed. This may have been affected by the low percentage of climbers reporting AMS symptoms, as well as limited power. Descending climbers had a 3.6 times increased risk of CO exposure compared with ascending climbers and had significantly higher COHb scores. Increased hours of stove operation was significantly linked to climbers who also met criteria for AMS.
authors.affiliation: Family Medicine Residency of Idaho, 777 Raymond St, Boise, ID 83704, USA. jclayroscoe@hotmail.com
authors.forename: Clay
authors.initials: C
authors.lastname: Roscoe
authors.forename: Ed
authors.initials: E
authors.lastname: Baker
authors.forename: Caitlin
authors.initials: C
authors.lastname: Gustafson
authors.forename: Todd
authors.initials: T
authors.lastname: Arndt
authors.forename: Jennifer
authors.initials: J
authors.lastname: Dow
authors.forename: Emily
authors.initials: E
authors.lastname: Johnston
authors.forename: Aaron
authors.initials: A
authors.lastname: Brillhart
mesh_terms: D000208:Acute Disease; D000328:Adult; D000413:Alaska; D000532:Altitude Sickness / Q000097:blood* / Q000209:etiology / Q000473:pathology; D002248:Carbon Monoxide / Q000097:blood*; D002263:Carboxyhemoglobin / Q000378:metabolism*; D016022:Case-Control Studies; D003296:Cooking; D005260:Female; D006801:Humans; D008297:Male; D009051:Mountaineering; D010092:Oximetry; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires
chemical_list: D002248:Carbon Monoxide; D002263:Carboxyhemoglobin