A computer-controlled anaesthetic gas mixer.

The theory and construction of a prototype computer-controlled gas mixer and flow regulator are described. The device is capable of controlling and mixing flows of oxygen, nitrous oxide and air. The accuracy and repeatability of the device is very high under given conditions, and its performance is quantified. The flow rate and oxygen concentration are selected from a microcomputer and the control program is written in BASIC. Possible improvements to the system are discussed as are uses in both clinical and research work.