Examples of draw-over vaporizers include:

• Epstein, Macintosh, Oxford (EMO) - uses ether only
• Oxford Miniature Vaporizer (OMV) - May be used for different volatile agents (select scale for appropriate agent). A stainless steel wick in the vaporising chamber increases the surface area for vaporization and hence the efficiency of the vaporizer. Two OMVs in series were used as part of the original Triservice apparatus. Capacity only 50 ml. The OMV falls over easily: an inspired halothane concentration >30% is delivered if liquid halothane enters the breathing hose.

New draw-over vaporisers:

• Diamedica vaporizers
  • Halothane or isoflurane can be used in the same vaporizer
  • A sevoflurane vaporizer is also available - 150 ml capacity, stable
• OES vaporizer
  • Part of the Universal Anaesthetic machine
  • Two models available (halothane and isoflurane)

Vaporisers designed to be used with compressed gas and continuous flow (known as plenum vaporisers) have a very high internal resistance to gas flow. These should never be used for draw-over anaesthesia as they are too difficult to breathe through.