ABSTRACT
The first purpose-built anaesthetic machine was developed in 1917 by the British anaesthetist Henry Boyle. The anaesthetic machine is a fundamental piece of equipment and it is a basic requirement that all anaesthetists understand how it works and how to check it. Anaesthetic machines should be checked at the start of every operating session, with additional checks being carried out for each new patient or in the event of any equipment changes. 'Bourdon' pressure gauges measuring the pressure in the gases delivered from both the pipelines and the cylinders can be found mounted on the front of the anaesthetic machine. The purpose of the pressure-reducing valves is to convert the high and variable pressures from the cylinders into a constant pressure just below that of pipeline pressure. Rotameters or flowmeters are found grouped in a unit on the front of traditional anaesthetic machines; newer machines tend to have digital readings of gas flows.
