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The Veterinary Anaesthetic Machine Made Simple - Part 1

Posted in Operations @ Dec 1st 2016 - By Dr Jen Davis BVMS Masters Vet Anaes. MANZCVS (Anaesthesia and Critical Care) DipECVAA
The Veterinary Anaesthesia Machine Made Simple

Dr Gas Vet's first post in a helpful series all about the veterinary anaesthetic machine

Originally published on the Vet Anaesthesia Tips blog 29/7/2016: The Anaesthetic Machine: Made Simple

This is the beginning of a series of blogs about the anaesthetic machine. My aim is to provide a basic and simple understanding of how your anaesthetic machine works.

How does your anaesthetic machine work?

Anaesthetic machines can be very confusing, especially if you only use them occasionally or if you are faced with a new machine.  A thorough understanding of the basic elements of an anaesthetic machine should make it possible for you to easily set-up, test and trouble-shoot any machine.

When I talk about the ‘anaesthetic machine’ I don’t include breathing systems. These  should be considered separately to the machine itself. Hence, I do not include soda lime canisters, APL valves or expiratory/inspiratory valves here. These may be permanently attached to your anaesthetic machine, but they are actually part of a rebreathing CIRCLE system. 

Understanding that these elements are part of a breathing system rather than the machine itself makes life much easier when it comes to attaching a breathing system, especially a non-rebreathing (e.g. Bain) system!

The basic elements...

The basic elements that should be present in any anaesthetic machine are:

  • A gas supply (cylinders and/or pipeline)
  • Pressure gauges (for gas supply)
  • Pressure-reducing valves (for gas supply)
  • Backbar
  • Flowmeter(s)
  • Vaporiser(s)
  • Oxygen failure warning device
  • Pressure relief valve
  • Oxygen flush system
  • Common gas outlet
  • Gas scavenging system (not technically part of the anaesthetic machine itself, but important to mention)

The above elements are listed in order from gas supply (highest pressure), to the common gas outlet where a patient breathing system is attached (lowest pressure).

I will go through each of these elements separately over the next few months.

I will attach photos and videos to illustrate my blogs as we go along. But it’s a great idea to have a look at the anaesthetic machines in your practice as we go; to identify each element and understand how it works.

Click here to read The Veterinary Anaesthetic Machine Made Simple Part 2: Gas Cylinders

About Jen

Dr Jen Davis (@Dr GasVet) is a European Specialist in Veterinary Anaesthesia and Analgesia. She is currently undertaking a PhD at Murdoch University, investigating the early diagnosis of acute kidney injury induced by anaesthesia-related hypotension.

Jen also works part-time as registrar in veterinary anaesthesia at The Animal Hospital at Murdoch University, where she administers sedation, anaesthesia, and analgesia to all species of animal, as well as teaching undergraduate students and resident vets studying to become anaesthesia specialists.

A summary of Jen’s research, and open access to her published work can be found on ResearchGate.

For more excellent posts on veterinary anaesthesia vist Jen's blog: Vet Anaesthesia Tips and register to receive notifications of new posts by email

You can also follow Jen on:

Twitter: Vet Anaesthesia Tips  |  Facebook: Veterinary Anaesthesia Tips


Sonja Michele Michele Anderson @ Dec 22nd 2020 9:02pm
Thank you for your help. Sonja xx

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