• Martin Grossherr, Andreas Hengstenberg, Torsten Meier, Leif Dibbelt, Klaus Gerlach, and Hartmut Gehring.
• Department of Anesthesiology, University Clinic of Schleswig-Holstein, Campus Luebeck, Germany. martin_grossherr@hotmail.com
• Anesthesiology. 2006 Apr 1;104(4):786-90.

BackgroundAnalyzing propofol concentration in expired alveolar gas (cPA) may be considered as a convenient, noninvasive method to follow the propofol concentration in plasma (cPPL). In the current study, the authors established procedures to measure cPA and cPPL for the assessment of their relation in two animal models during anesthesia.MethodsExpired alveolar gas and mixed venous and arterial blood were simultaneously sampled during continuous application of propofol for general anesthesia to three goats and three pigs. Propofol infusion rates were varied to modify plasma concentrations. cPA, sampled cumulatively over several respiratory cycles, was quantified by thermal desorption gas chromatography-mass spectrometry. cPPL was determined using reversed phase high-performance liquid chromatography with fluorescence detection.ResultscPA ranged from 0 to 1.4 and from 0 to 22 parts per billion in goats and pigs, respectively, at cPPL of 0-8 microg/ml. The relation between cPA and cPPL was linear; however, the slopes of the regression lines varied between animals.ConclusionPropofol can be quantified in expired alveolar gas. The results stress the role of marked species-specific variability.

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