title: Methane accumulation during closed-circuit anesthesia.
abstract: When using the closed-circuit PhysioFlex apparatus for ventilating patients with an O2/air mixture during total intravenous anesthesia (TIVA) for gynecologic laparoscopy, we noticed that the built-in infrared analyzer indicated unexpected values for halothane. In 10 ASA grade I or II patients, the breathing gases were analyzed at the end of the ventilation for the presence of methane, which could be traced in all patients. Mean concentration was 861 ppm after a mean closed-circuit anesthesia time lasting 78 min. The unexpected halothane concentration at the time of gas sampling indicated an average of 1.0%. The anesthetic vapor analysis by infrared absorption is clearly disturbed by the presence of methane.
authors.affiliation: Department of Anesthesia, University Hospital, Ghent, Belgium.
authors.forename: G
authors.initials: G
authors.lastname: Rolly
authors.forename: L F
authors.initials: LF
authors.lastname: Versichelen
authors.forename: E
authors.initials: E
authors.lastname: Mortier
mesh_terms: D000328:Adult; D000764:Anesthesia, Closed-Circuit; D006801:Humans; D008697:Methane / Q000378:metabolism*
chemical_list: D008697:Methane