CUH makes major greenhouse gas cuts

The Trust is saving the equivalent of 2,350 tonnes of carbon dioxide, comparable to around 330 fossil-fuelled car trips around the world a year, by cutting down its use of nitrous oxide.

Nitrous oxide (N2O) has been used in anaesthesia for over 300 years, both for its pain-relieving properties and as an anaesthetic gas.

Anaesthetic gases make up around 5% of the NHS carbon footprint. Nationally, the NHS has committed to achieving an 80% reduction in its carbon footprint by 2028 and net-zero emissions by 2040.

Over the past three years, CUH estates and clinical colleagues have been working to reduce leakage losses by decommissioning the N2O manifolds delivering the gas supply through pipe networks across its site. This involved detailed planning, including ensuring an alternative supply of portable cylinders of N2O for the operating theatres.

“We started planning decommissioning the manifolds in 2021 as part of the national move away from relying on them to deliver the gas,” said Max Rokoszak, CUH Energy Manager. “The proposal was to move from three pipe networks supplied from gas tanks and manifolds to using portable cylinders, which are far more efficient and sustainable.

“We presented our proposals to the Trust’s Medical Gas Committee and one of our main areas of focus was to reassure colleagues using N2O, that portable cylinders are completely efficient and effective. For example, we were able to prove that the supply pressure was constant and wouldn’t drop as the cylinder was used.

“We estimate that we’ll use around 60 portable cylinders across the site a year, instead of the equivalent of around 1,500. We’ll monitor the number, so our patients and clinicians have what they need and there is also environmental and financial sustainability,” said Max.

One of the clinicians involved in the decommissioning project was consultant anaesthetist Dr Grace Nisbet. Part of her role was to make sure that, from a clinical point of view, decommissioning was straight forward and the move to using cylinders went as smoothly as possible.

“We wanted to continue to use nitrous oxide for each and every patient who clinically needs it, but at the same time we also wanted to be able to use it in the most sustainable way possible,” she said. “There is a national move away from using pipes to supply nitrous oxide because we know that they are inefficient, and this inefficiency contributes to climate change.

“Nitrous oxide has many uses in anaesthesia. We often start a general anaesthetic for children with a gas induction, where children breathe through a mask and then fall asleep. Nitrous oxide can be one of the gases used for this. It allows children to be asleep when we put a canula in, which is something a lot of them find very distressing if they are awake.”

Nitrous oxide, when mixed 50-50 with oxygen can also be used by patients to help relieve pain in the form of Entonox or ‘gas and air’. Working towards a mobile cylinder solution for this is the next part of CUH’s journey in permanently driving out nitrous oxide waste and loss.

“Successfully completing this decommissioning is a major step forward in the delivery of the Trust’s Green Plan programme for the 2020’s. We are just concluding our first phase of this programme in which CUH’s direct carbon emissions were drawn-down by over 10% (2019/20 baseline) alongside a raft of measures to cut waste through reducing, reusing, repairing, remanufacturing and recycling.

“The key success stories include upgrading boiler efficiency and lighting, installation of electric vehicle charging, the deployment of solar-powered high efficiency heat-pumps for the new Cambridge Movement Surgical Hub, and taking a collaborative lead in establishing the Circular Economy Healthcare Alliance to develop reuse over single-use wherever safe and viable,” said Carin Charlton, CUH’s board-level net zero lead.

Click on the following link to watch a video about how the supply of nitrous oxide at CUH (opens in a new tab) has been improved.