Anaesthetic Equipment checks

Are you Good to Go?

The anaesthetist has a primary responsibility to understand the function of the anaesthetic equipment and to check it before use.


  • Check for breakages, cracks and missing parts
  • Has it been cleaned/disinfected?

Check contents are all present, sterile as appropriate and in-date


  • Check the scavenging system is operational (and is turned on when appropriate)
  • Ensure that the tubing is attached to the appropriate exhaust port of the breathing system, ventilator or anaesthetic workstation
  • When was it last serviced and is it due?

Check the O2 supply source is on:

If this is a cylinder

  • Do you need to change the cylinder?
  • Do you need to order more supplies?

If this is a concentrator/generatorIs

  • Is it plugged in and turned on?
  • Date of last service – is it current?
  • Check all cylinders for cracks/dents – don’t use, if it is!
  • Care should be taken to see that sealing washer (Bodok Seal) is present on the yoke and is in good condition to prevent leakage
  • Check the pipeline gas is connected (Shrader Probe connected) or the 02 concentrator/generator is switched on and working
  • Check the O2 flowmeter is working (the bobbin is revolving/floating freely and not sticking) and the control valve works smoothly
  • If the machine uses attached cylinders / back-up cylinder – attach & turn on each cylinder to check there are no leaks (‘hissing’)
    -Back-up cylinder. It’s vital to check the ‘back-up’ cylinder is fully functional, and has enough gas remaining to do a full op. You might need to rely on it!
  • Do all cylinders have the appropriate tag on? – FULL, IN USE or EMPTY



  • Turn on OXYGEN flow to 8l/min and then disconnect the pipeline/cylinder supply and the bobbin on the flowmeter should drop and trigger an alarm which should shut off when the supply is reconnected and turned back on.
  • Check the Oxygen Flush works
  • Check the O2 supply concentration

If you use N2O – check cylinder and flowmeter function, (with scavenging on). It is not possible to check contents by looking at the dial – contents are measured by weight of the cylinder.

The contents of these cylinders can be accurately measured by weighing the cylinders (1.87 g/L of gas) rather than by pressure gauge. The pressure depends on the vapour pressure of liquid and so does not indicate the amount of gas remaining in the cylinder if the contents are partly in the liquid phase. The pressure stays the same until all the liquid is converted to gas; after which the pressure falls until the cylinder is exhausted. Cylinder pressure varies only if temperature changes due to rapid emptying of cylinder causing cooling of contents due to absorption of latent heat of vaporization. Under this condition, cylinder pressure will decrease with cooling but will be restored as the cylinder warms up again.


  • Ensure it is mounted securely and locked onto the backbar (if it is a removable cannister). There must be enough volatile agent. The vaporizer dial must move easily through its whole rage and not stick. Check that the filler cap is closed.
  • Check when the next service is due. Report if close to or exceeding the 12-month recommended limit.

Manual leak test of vaporiser

(ONLY if permitted by manufacturer recommended instructions)

Set a flow of oxygen of 5L/min and with the vaporiser turned off, temporarily occlude the common gas outlet. There should be no leak from any part of the vaporiser and the flowmeter bobbin should dip.

Defect and Assembly checks

  • Check all breathing systems visually for defects (discard if in doubt)
  • Check the breathing system is assembled correctly and not missing any parts
  • Visually check the reservoir bags are intact (no holes, splits or tears)

1.The Quick-Squeeze Bag Test – checking the breathing system and reservoir bag

  • Attach the breathing system as normal with a reservoir bag
  • Close the APL
  • Occlude the breathing system (patient-delivery end)
  • Press the oxygen flush
  • Squeeze the bag
    – if the bag deflates, you have a leak in either the bag or the breathing system
    – change the bag for a new (or tested) one. Re-test
    – if the bag deflates it is most likely the breathing system has a leak (discard)
    – if the new bag remains inflated, it is likely the previous bag has a leak (discard)

2.The 2-Bag Test – checking the APL

  • Attach the breathing system as normal with a new (or tested) reservoir bag
  • Attach a new (or tested) reservoir bag to the patient end of the breathing system
  • Set fresh gas flow to 5L/m
  • Check the APL valve is working by squeezing both bags

Check that the cannister is sufficiently filled

Replace if a colour-change is more than 2/3rds of the cannister or after 14 hours of use


  • Check the endotracheal tubes, masks etc. are all available in the appropriate sizes, at the point of use, and that they have been checked for patency and (if cuffed) the cuff is functional; check they are clean!
  • Check that the appropriate laryngoscope is available, with appropriate head-sizes, and is functional


  • Check that your anaesthetic monitoring equipment is working e.g. pulse oximeter, multi-parameter monitor, Doppler, ECG etc

And finally; let there be notes!


  • A clear note should be made in the patient’s anaesthetic record that the anaesthetic machine check has been performed, that appropriate monitoring is in place and functional, and that the integrity, patency and safety of the whole breathing system has been assured
  • A record should also be kept with each anaesthetic machine to evidence the daily pre-session checks. Documentation of the routine checking and regular servicing of anaesthetic machines and patient breathing systems should be sufficient to permit audit on a regular basis