ANESTHESIA WITH THE BOYLES BOTTLE VAPORIZER

Having used the Boyle's bottle vaporizer apparatus out of necessity in a developing country, the concentration of agent that had been admini stered was investigated retrospectively. Three anaesthetic agents, hal othane, isoflurane and enflurane, were measured at different temperatu res, using a Boyle's anaesthetic machine and a Boyle's bottle in circu it with a Magill breathing system connected to a Rascal II Agent Monit or. Bubbling a fresh gas flow of 51.min(-1) through the anaesthetic li quids generated concentrations in excess of 12%. Elevating the initial temperature of the vaporizer increased the delivered concentration, a lthough this effect was short-lived. Therapeutic concentrations of vap our were achieved for all three agents by avoiding bubbling and manipu lating the 'splitting ratio' lever. The Boyle's bottle vaporizer may b e used with modern anaesthetic agents such as halothane, isoflurane an d enflurane. However, the limitations of and variations between vapori zers should be borne in mind. An agent monitor employed at the patient end of the circuit would be an important safety feature.