Anesthesia-associated carbon monoxide exposures among surgical patients.
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.
Pearson
M L
ML
Division of Healthcare Quality Promotion, National Center for Infections Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA.
Levine
W C
WC
Finton
R J
RJ
Ingram
C T
CT
Gay
K B
KB
Tapelband
G
G
Smith
J D
JD
Jarvis
W R
WR
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
D002245:Carbon Dioxide; D002263:Carboxyhemoglobin