The National Nitrous Oxide Mitigation Project

Nitrous oxide has been commonly used as both an anaesthetic and analgesic agent for over a century. There is diminished use in contemporary anaesthesia, often limited to limited to complex dental cases, paediatric inductions and obstetric emergencies requiring gaseous anaesthesia. Nitrous Oxide is also a potent greenhouse gas.

In the theatre setting, nitrous oxide is usually supplied via a manifold of cylinders to enable a continuous, uninterrupted supply. Recent work has demonstrated that the majority of nitrous oxide manifolds in the United Kingdom and Ireland have a significant leak (with 83%-100% of nitrous oxide leaking out to the atmosphere before reaching point of delivery), placing a significant burden on environmental and atmospheric health, as well as being financially wasteful.

A consensus statement supported by the CAI states that all anaesthetic Nitrous Oxide Manifolds should be decommissioned by 2026/2027.

There is ongoing demand for Entonox (50:50 Nitrous:Oxygen mixture) for labour analgesia, however there are also significant leaks and stock management issues in this supply line. Furthermore, occupational exposure to leaky nitrous oxide supply can lead to serious health problems such as anaemia, neurological dysfunction, and fertility issues.

The CAI Sustainability Committee has supported the development of a National Nitrous Oxide Mitigation Project group. The project also sits withing the HSE Climate Action Strategy. The members include Dr Tim Keady, Dr Donall O Croinin, Dr Ola Nordrum, Dr Oscar Duffy, Dr Hugh O’Callaghan, Damien Clarke HSE Engineering Advisor. We have estimated the size of the problem, and found that there is significant inter-hospital variability. Education on nitrous oxide mitigation alone has not been successful. We have therefore opened direct lines of communication with hospitals, starting with the largest users of Nitrous Oxide.

Progress to date

• Three hospital site visits
• Twelve sites have implemented nitrous oxide mitigation strategies
• Four sites have decommissioned nitrous oxide manifolds