Goldman Halothane Vaporizer is a small and simple apparatus used for administration of halothane. It is not a component of boyle anaesthetic machine but can be attached to it. It is neither temperature and level compensated nor accurately calibrated. It can be used either inside or outside the anaesthetic breathing circuit. But halothane concentration using this vaporizer is usually low and its output is mainly influenced by gas flow rate.

The vaporizer essentially consists of a small glass pot attached to a metal head. On the side of the head there is an outlet of gases and on other side there is an inlet where carrier gases are received and/or divided partly in the vaporizing chamber and the rest to bypass channel. At the top of the head there is a control device which can be rotated to the alter the vaporizer output. It is easy to operate, has low resistance to gas flow and needs little servicing.

It was originally designed for use with dental anaesthetic apparatus, but is now being popularly used in continuous flow type of machine like Boyle anaesthetic machine, usually alongside other vaporizers. It can also be used in circle system by incorporating into the inspiratory limb of a carbon dioxide absorption unit. This position is better called as vaporizer inside the circle. Maximum concentration using the vaporizer never exceeds 2% irrespective of the total gas flows.

Changes in temperature

No compensation is made for the effect of changes in temperature on SVP, so the output of such vaporizers is highly dependent upon the ambient temperature: Effect of changes in temperature on the output concentration of a simple halothane vaporizer calibrated at 20 oC.

Time

The delivered concentration will also be reduced over time, since loss of the latent heat of vaporization causes the liquid to cool and lowers the saturated vapor pressure. This is most noticeable in the case of ether vaporizers, where ice may form on the outside of the vaporization chamber due to the extreme cold which develops owing to evaporation.

Accuracy

Because of these causes of variability in their output, simple vaporizers cannot generally be provided with a scale indicating the concentration of anesthetic being delivered. Most merely have some qualitative scale such as Off to On, or 0 to 10. Adjustments to the vaporizer can only be made on the basis of the response of the patient as judged by changes in the plane of anesthesia.