Malignant hyperthermia and the clean machine.

Following use with halothane, ten anaesthestic machines were sampled using infrared analysis for halothane contamination. Baseline measurements of halothane were made in the room and at the machine's common gas outlet. Five per cent halothane with four litres per minute oxygen flow was delivered for ten minutes into a scavenged breathing circuit. Halothane was then discontinued, an oxygen flow rate of 12 litres per minute was begun, and continuous measurements were made until the halothane concentration became undetectable. Baseline measurements of the rooms and anaesthestic machines ranged from 0 to 0.8 parts per million. Following the oxygen flow, the halothane concentration decreased to undetectable levels within six minutes in all ten machines.