Faculty Collaboration Database

Carbon monoxide production from sevoflurane breakdown: modeling of exposures under clinical conditions. Anesth Analg 2003 Mar;96(3):757-764

Date

02/25/2003

Pubmed ID

12598259

DOI

10.1213/01.ANE.0000049584.64886.39

Scopus ID

2-s2.0-0037369619 (requires institutional sign-in at Scopus site)   44 Citations

Abstract

UNLABELLED: Isoflurane, enflurane, sevoflurane, and especially desflurane produce carbon monoxide (CO) during reaction with desiccated absorbents. Of these, sevoflurane is the least studied. We investigated the dependence of CO production from sevoflurane on absorbent temperature, minute ventilation (VE), and fresh gas flow rates. We measured absorbent temperature and in vitro CO concentrations when desiccated Baralyme reacted with 1 minimum alveolar anesthetic concentration of (2.1%) sevoflurane at 2.3-, 5.0-, and 10.0-L VE. Mathematical modeling of carboxyhemoglobin concentrations was performed using an existing iterative method. Rapid breakdown of sevoflurane prevented the attainment of 1 minimum alveolar anesthetic concentration with low fresh gas flow rates. CO concentrations increased with VE and with absorbent temperatures exceeding 80 degrees C, but concentrations decreased with higher fresh gas flow rates. Average CO concentrations were 150 and 600 ppm at 2.3- and 5.0-L VE; however, at 10 L, over 11,000 ppm of CO were produced followed by an explosion and fire. Methanol and formaldehyde were present and may have contributed to the flammable mixture but were not quantitated. Mathematical modeling of exposures indicates that in average cases, only patients < or =25 kg, or severely anemic patients, are at risk of carboxyhemoglobin concentrations >10% during the first 60 min of anesthesia.

IMPLICATIONS: Sevoflurane breakdown in desiccated absorbents is expected to result in only mild carbon monoxide (CO) exposure. Completely dry absorbent and high minute ventilation rates may degrade sevoflurane to extremely large CO concentrations. Serious CO poisoning or spontaneous ignition of flammable gases within the breathing circuit are possible in extreme circumstances.

Author List

Holak EJ, Mei DA, Dunning MB 3rd, Gundamraj R, Noseir R, Zhang L, Woehlck HJ

Author

Harvey J. Woehlck MD Professor in the Anesthesiology department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Algorithms
Anesthetics, Inhalation
Carbon Monoxide
Carboxyhemoglobin
Desiccation
Methyl Ethers
Models, Biological
Spectrophotometry, Infrared
Time Factors