VAPORIZER

Typical Number in Hospital: 50

Cost Bands: 2

References: 2

Although one might expect this term to be applied to any form of vaporizer, perhaps including humidifiers and nebulizers, it is normally reserved for devices for producing vapour from volatile anaesthetic agents such as ether, chloroform, Halothane, etc. These are used to introduce such agents into the inspired gases during anaesthesia. Gases are blown through, over the surface, or over a wick of the volatile liquids to produce vapour.

Earlier types were simple bubble-through devices but modern vaporizers are complex with relatively accurate calibration and temperature compensation, usually with the aid of a thermostatically controlled valve.

They usually fit on to the back bar of the anaesthetic machine so that the gas mixtures from the flowmeters can pass through, collecting the vapour. Although there are some types which can take a variety of anaesthetic agents, the trend is to provide temperature compensated and calibrated units for single agents. They consist of terminal connections on to the back bar, a reservoir, wick or other dispersing mechanism, a temperature- compensating mechanism and a control system.

Types which may be found include the copper kettle, draw over, Fluotec, Abingdon, Oxford, Enfluoratec, Pentec, and others. Special 'draw over' types which provide a very low resistance to the flow of gas are made for intermittent (demand) flow apparatus, for dental anaesthesia, and for circle rebreathing circuits.