[Gaschromatographic examination of the expired air after anaesthesia with halothane, enflurane and methoxyflurane (author's transl)].

The concentration of anaesthetic gases in the expired air was studied for up to 17 days in patients who had been anaesthetized with methoxyflurane, enflurane or halothane. The estimation were made by means of gaschromatography. The rate and duration of elimination of the anaesthetic via the lungs depends on the fat stores of the patient (as calculated by the body weight/stature ratio), the length of anaesthesia and the Lutz index (calculated average concentration of the inhaled anaesthetic). The concentration of anaesthetic gases in the expired air fell steeply during the first 12 hours after anaesthetic and then decreased more gradually. The drop in concentration during the first 24 hours was steepest for methoxyflurane, followed by halothane and enflurane in that order. The results are in fair agreement with the rate of metabolization of the three anaesthetic agents. The investigation showed that during the first after anaesthesia appreciable quantities of anaesthetic gases are eliminated via the lungs and, consequently, released into the air of the recovery room.