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The response of anesthetic agent monitors to trifluoromethane warns of the presence of carbon monoxide from anesthetic breakdown. J Clin Monit 1997 May;13(3):149-55

Date

05/01/1997

Pubmed ID

9234084

DOI

10.1023/a:1007390722425

Scopus ID

2-s2.0-0031148333 (requires institutional sign-in at Scopus site)   11 Citations

Abstract

OBJECTIVE: Trifluoromethane and CO are produced simultaneously during the breakdown of isoflurane and desflurane by dry CO2 absorbents. Trifluoromethane interferes with anesthetic agent monitoring, and the interference can be used as a marker to indicate anesthetic breakdown with CO production. This study tests representative types of gas monitors to determine their ability to provide a clinically useful warning of CO production in circle breathing systems.

METHODS: Isoflurane and desflurane were reacted with dry Baralyme at 45 degrees C. Standardized samples of breakdown products were created from mixtures of reacted and unreacted gases to simulate the partial degrees of reaction which might result during clinical episodes of anesthetic breakdown using 1% or 2% isoflurane and 6% or 12% desflurane. These mixtures were measured by the monitors tested, and the indication of the wrong agent or a mixture of agents due to the presence of trifluoromethane was recorded and related to the CO concentration in the gas mixtures.

RESULTS: When presented with trifluoromethane from anesthetic breakdown, monochromatic infrared monitors displayed inappropriately large amounts of isoflurane or desflurane. Agent identifying infrared and Raman scattering monitors varied in their sensitivity to trifluoromethane. Mass spectrometers measuring enflurane at mass to charge = 69 were most sensitive to trifluoromethane.

CONCLUSION: Monochromatic infrared monitors were unable to indicate anesthetic breakdown via interference by trifluoromethane, but did indicate falsely elevated anesthetic concentrations. Agent identifying infrared and Raman monitors provided warning of desflurane breakdown via the interference of trifluoromethane by displaying the wrong agent or mixed agents, but may not be sensitive enough to warn of isoflurane breakdown Some mass spectrometers provided the most sensitive warnings to anesthetic breakdown via trifluoromethane, but additional data processing by some patients monitor units reduced their overall effectiveness.

Author List

Woehlck HJ, Dunning MB 3rd, Kulier AH, Sasse FJ, Nithipataikom K, Henry DW

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

Air Pollutants, Occupational
Anesthetics, Inhalation
Carbon Monoxide
Chlorofluorocarbons, Methane
Environmental Monitoring
Humans
Isoflurane
Mass Spectrometry
Spectrophotometry, Infrared
Spectrum Analysis, Raman