title: Anesthesia-associated carbon monoxide exposures among surgical patients.
abstract: OBJECTIVE
  To estimate the extent of, and evaluate risk factors for, elevated carboxyhemoglobin levels among patients undergoing general anesthesia and to identify the source of carbon monoxide.
  
  
  METHODS
  Matched case-control study to measure carboxyhemoglobin levels.
  
  
  METHODS
  Large academic medical center.
  
  
  METHODS
  45 surgical patients who underwent general anesthesia
  
  
  RESULTS
  Case-patients were more likely than controls to undergo surgery on Monday or Tuesday (10/15 vs 7/30; matched odds ratio [mOR], 7.7; 95% confidence interval [CI95], 1.8-34; P=.01), in one particular room (7/15 vs 4/30; mOR, 8.5; CI95, 1.5-48; P=.03) or in a room that was idle for > or =24 hours (11/15 vs 1/30; mOR, 95.5; CI95, 8.0-1,138; P< or =.001). In a multivariate model, only rooms, and hence the anesthesia equipment, that were idle for > or =24 hours were independently associated with elevated intraoperative carboxyhemoglobin levels (OR, 22.4; CI95, 1.5-338; P=.025). Moreover, peak carboxyhemoglobin levels were correlated with the length of time that the room was idle (r=0.7; CI95, 0.3-0.9). Carbon monoxide was detected in the anesthesia machine outflow during one case-procedure. No contamination of anesthesia gas supplies or CO2 absorbents was found.
  
  
  CONCLUSIONS
  Carbon monoxide may accumulate in anesthesia circuits left idle for > or =24 hours as a result of a chemical interaction between CO2-absorbent granules and anesthetic gases. Patients administered anesthesia through such circuits may be at increased risk for elevated carboxyhemoglobin levels during surgery or the early postoperative period.
authors.affiliation: Division of Healthcare Quality Promotion, National Center for Infections Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA.
authors.forename: M L
authors.initials: ML
authors.lastname: Pearson
authors.forename: W C
authors.initials: WC
authors.lastname: Levine
authors.forename: R J
authors.initials: RJ
authors.lastname: Finton
authors.forename: C T
authors.initials: CT
authors.lastname: Ingram
authors.forename: K B
authors.initials: KB
authors.lastname: Gay
authors.forename: G
authors.initials: G
authors.lastname: Tapelband
authors.forename: J D
authors.initials: JD
authors.lastname: Smith
authors.forename: W R
authors.initials: WR
authors.lastname: Jarvis
mesh_terms: D000328:Adult; D000368:Aged; D000768:Anesthesia, General / Q000009:adverse effects* / Q000295:instrumentation; D002245:Carbon Dioxide / Q000378:metabolism; D002249:Carbon Monoxide Poisoning / Q000209:etiology*; D002263:Carboxyhemoglobin / Q000378:metabolism; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D019570:Inhalation Exposure / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D013514:Surgical Procedures, Operative
chemical_list: D002245:Carbon Dioxide; D002263:Carboxyhemoglobin