Abstract
A minimum fresh gas flow of 1 litre per minute per mask and an inspired concentration of 2-3% halothane was required to induce anaesthesia in rats in 1-2 min. Anaesthesia was maintained with an inspired concentration of 1·5-2% halothane. Arterial carbon dioxide concentration increased during anaesthesia and was not reduced by increasing the flow of fresh gas.
Using the apparatus described here, halothane vapour concentration in the operator's breathing zone was 5 ppm. Prior to its introduction, levels of 250 ppm had been recorded in a poorly-ventilated animal room.