DISADVANTAGES:- Heavy, No Alarms
Dr. David Lyness
Equipment in Anaesthesia and Critical Care: A complete guide for the FRCA - Aston et al (Vaporiser Schematic)
Modern plenum vaporisers have high resistance to gas flow and are available for use with sevoflurane, isoflurane, enflurane and halothane.
For example, sevoflurane has an SVP of 157mmHg at 20°C. Therefore, gas leaving the vaporizing chamber will contain sevoflurane at a vapour pressure of 157mmHg.
It must then be diluted 10–20 times by the bypass gas to give a useful concentration.
The baffles force the entering FGF closer to the surface of the volatile.
Due to the wicks and baffles, this is system
of high resistance.
As liquid evaporates, it loses energy as the latent heat of vaporization, causing cooling.
Saturated vapour pressure (SVP) of a substance varies with its temperature but not with ambient pressure.
- If the atmospheric pressure is altered (for example, at high altitude), the SVP of the anaesthetic does not change, and therefore the vapour pressure
1atm = 1kPa