This page will collate information relevant for institutions considering decommissioning of nitrous oxide pipelines. It will include strategies for cylinder provision and process for decommissioning.

UK and Ireland Anaesthesia bodies have recommended nitrous pipelines be decommissioned and cylinders used in lieu. In Australia/NZ the relevant Colleges (ANZCA), Societies (ASA, NZSA), expert bodies (DEA) Infrastructure standards (AusHFG) and State Guidelines (eg: NSW guidelines ), support decommissioning of nitrous oxide gas pipelines and the avoidance of installation of new pipelines. So how to go about decommissioning your likely leaky nitrous pipes? A proposed phased approach outlined below.

A number of leading Australian and New Zealand institutions have already decommissioned their pipelines see the list below

A more detailed over-view of decommissioning nitrous pipelines and background is available in a review article published November 2025 in Australasian Anaesthesia Journal.
Back to the future: A return to point-of-care nitrous oxide cylinders (Woinarski C et al, 2025)

Phase 1 – Cut off dead wood

Disconnect and decommission nitrous pipeline from all areas which do not use nitrous oxide. Examples may include outpatients, emergency departments, radiology areas and areas connected for historical reasons. Portable entonox cylinders can be available for use in clinical areas

Removing unused limbs of the pipeline is important. Every metre of pipeline removed is a metre less that can leak

The Fremantle Hospital theatres set up for PRN Nitrous Oxide using a C-size cylinder

Phase 2 – Cylinders for theatres, wards and ED

Stop using pipelines for operating theatre nitrous oxide. Provide N2O cylinders, with regulator either connected directly to anaesthetic machine, or available to be brought in on a trolley and connected to nitrous oxide gas hose when required.

Maintain theatre pipeline to provide reassurance to staff until trial complete.

Wards and ED can have entonox cylinders or nitrous cylinders with a mixer used for procedures.

Phase 3 – Cylinders for birthsuite

The birthsuite can be supplied by local entonox cylinders which are mobile, allowing better access to N2O in shower or areas of room. A number of large birthsuites have now switched to point of care cylinders and report improved experiences for staff and patients, allowing more mobility for the labouring mother and satisfaction.

With enough investment and resources , it may be possible that a small manifold system for a birthsuite can be maintained, tested and kept leak proof. A digital continuous measurement flowmeter should be installed on any pipeline to ensure latent leaks are detectable. The initial and ongoing maintenance costs of a pipeline plus the reduced mobility of mothers using wall-based nitrous means most birth suites will likely transition to point of care cylinders.

Do you have a better way of phasing out your leaky nitrous pipelines? Let us know!

Hospitals which have decommissioned nitrous oxide pipelines (AU/ NZ)

Hospital	Services relevant to N2O	Date Decommissioned	Comments
Sir Charles Gairdner Hospital, WA	Tertiary Adult Neurosurgery, cardiac. >10 theatres	2022-2023	First in WA.
Burwood Hospital, NZ		2022
Prince Charles, QLD	Tertiary cardiac. 690 beds	2024-1
Broome Hospital, WA	300 Births/yr, low risk paediatrics. 2 theatres	2024-11	First maternity hospital (Aus)
Dunedin Maternity, NZ	1500 births/yr	2024	60% of labouring mothers use entonox.
Kalamunda, WA	Endoscopy service	2025-5
St Vincents Public,		2025?
Modbury, SA	174 beds	2024?
Christchurch Public Hospital – NZ		2023 (Parkside) 2025 (Riverside)
Childrens Hospital Westmead, Sydney Childrens Hospital Network NSW	300 beds	2026 May	First major paediatric hospital to decommission. 4 Anaes machines with yokes and fixed cylinders, remainder portable cylinders connected by 400kpa hose. POC Cylinders use only since Jan 2026.
Fremantle Hospital, WA	8 theatres, 3 endoscopy suites	2026 February	POC Cylinders use since August 2025
Armadale Hospital, WA	2000 births	?2025 expected
Rockingham Hospital, WA	1500 births	February 2026	POC Cylinders use only (maternity and theatres) since June 2025
Cairns Hospital QLD	2600-2800 births/yr 12 operating theatres		POC Cylinders use planned from March 2026.

N2O Cylinder Provision: Anaesthesia

Possible strategies to provide nitrous oxide cylinders for anaesthesia are as follows

For Anaesthesia Consultants who require nitrous oxide for every case (minority) – provide a cylinder in theatre whenever that consultant is working. This may require several N2O D or C-sized cylinders per theatre complex, which can be connected via the flexible pipeline nitrous hosing. Need a regulator to drop cylinder pressure 400kpa.
For Consultants who can predict their likely need for nitrous oxide (eg: paeds gas inductions) provide C or D size nitrous oxide cylinder in theatre on request (with 400kpa regulator)
For theatres with regular paediatric gas inductions – have a C-size cylinder bolted to the rear of the machine, next to the oxygen backup cylinder. Most machines have capacity to have at least 2 cylinders secured to the rear of the machine (one oxygen and one nitrous oxide). Some machines allow 3 cylinders.

Brand	Model	Nitrous Oxide Cylinder Options	Reference
Drager	Perseus	C or D size nitrous oxide cylinder	Personal communication NSW Health
Drager	Zeus	Zeus does have capacity for nitrous backup cylinder connection along with air and O2 (see p23 IFU). A backup air cylinder should remain since the DIVA and sometimes suction are driven by air supply. Only space for 2 cylinders at a time though. If maintaining air and oxygen cylinders, a nitrous Oxide cylinder would have to connect via pipeline hose unless a harness can be developed to hold the 3rd cylinder (n2O)	Zeus IE IFU
GE	Aisys CS2	Up to 3 cylinder connections (although space may be an issue?) C cylinder nitrous oxide.	Aisys IFU
GE	Carestation 620 / 650 (not 650c)	2 cylinder connections, 3rd optional for ‘outboard’ cylinder. C cylinder nitrous oxide. Large cylinders (O2/N2O) optional.	Carestation IFU
Drager	Fabius	2 cylinders – O2 and N2O	Observation FSH

Anaesthesia Machine Compatibility with Fixed Nitrous Oxide Cylinders

How to set up a portable nitrous oxide cylinder for theatres

The swap-it when it’s low approach: Have a C or D sized cylinder which is swapped out at an agreed pressure. This is the easiest approach and has been successful in many hospitals in Australia.

When should a nitrous cylinder be replaced, in theatre?

It depends on the cylinder and how it is connected to the anaesthetic machine

A medical C cylinder has a water volume of 2.9l, 1.75 kg N2O =935 L at 1 atm.

With the function pressure of a cylinder being 4,600-5,200kPa, when connected via a yoke, a low pressure occurs alarm at 2633kPa, which correlates to about 70L remaining in an Australian C cylinder. This should give ample warning (280 minutes at 250ml N2O per min, or 14 minutes at 5 L N2O per min), and allow a cylinder change.

If a D cylinder is connected via a regulator and pipeline hose the first audible alarm will occur when the low N2O pressure alarm is reached at 254kPa (GE manual). At this threshold, there is approximately 25L of N2O in a D cylinder, providing enough warning to allow for a cylinder change.

Check out the Sydney Children’s Hospitals network guide to using point of care nitrous oxide cylinders

Engineers Perspective – Decommissioning a pipeline

We asked a hospital engineer recently involved in decommissioning a nitrous oxide pipeline to summarise the steps – here they are.

Letter from the Hospital confirming their approval to decommission the Nitrous Oxide
Undertake an audit of the current setup – Review the drawings and confirm on site for:
- Nitrous oxide outlets – location and quantity
- Routing of piping and location of isolations – for each building and if large building, if isolation for different floors.
- Locate all Medical gas alarm panels, the model. For some older system (as we had in our theatres were local with pressure switches and LEDs)

Decommissioning

Isolate building.
Critical step – shunt Nitrous Oxide alarm on the medical gas panels in the building and or pressure switch if mercury type with LED (old system)
Vent the outlets.
Plug with specially made plugs (we got ours made by in SS steel)
Add labels to all medical gas panels and all outlets plugged
Repeat to all buildings
Then disconnect main supply isolate and plug
Insert Label – Nitrous Oxide Decommissioned

POC = Point of care

Costs

Many hospitals describe the cost of decommissioning their nitrous oxide gas pipelines as similar to their annual maintenance cost. Once decommissioned, the savings on the maintenance of gas pipeline and hire of manifold cylinders will compound. There are some upfront costs to ensure adequate portable cylinder availability but this is usually very minor. Given that most hospitals reduce their volume of nitrous oxide purchased by 50-95%, there are additional ongoing savings there too.

To give an estimate, one major hospital in NSW, Australia was quoted in 2026 the following costs