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A way of dealing with the variation in the concentration of anaesthetic vapours due to temperature change (caused by rapid loss of latent heat of vaporization), and caused by variations in the gas flow, were dealt with in a simple way in 'copper kettle' type vaporizers such as the Halox. The temperature problem is dealt with by thermal damping either by copper, hot water (e.g. Oxford vaporizer), or by electricity (e.g. Heidbrink Kinet-O- Meter). Variations in gas flow are not a problem since a small quantity of oxygen from a separate rotameter is saturated with vapour (i.e. concentration is known ) and this carrier mixture is fed into the main anaesthetic gas flow. Unlike most vaporizers now in use, the result is a known delivery rate of the agent and not a known percentage of a variable gas flow.
Most copper kettle vaporizers employ a gauze or mesh in the liquid through which the gas is bubbled.
Content and Design Copyright 2000 Dr. Malcolm C Brown. See Title Page for more details