CHANGING the type of anaesthetic gas used to put patients to sleep in surgery has the potential to save the NHS in Scotland hundreds of thousands of pounds each year - and cut its carbon footprint.

It comes after anaesthetists in Inverness cut NHS Highland's anaesthesia bill by £73,000 last year by switching from one gas to a similar, cheaper alternative.

Like much of the NHS, Raigmore Hospital has previously used desflurane in general anaesthesia.

Read more: Psychiatrist says he was 'gaslighted' by Royal College in antidepressants row

However, this is 60 times more polluting that a similar hydrocarbon gas, sevoflurane.

Anaesthetic gases represent an estimated five per cent of the carbon footprint for all acute NHS organisations.

Once used, anaesthetic gases are are released into the atmosphere where they contribute to global warming, with desflurane known to be the most damaging. A study of atmospheric concentrations of anaesthetic gases in 2016 found that it was rapidly increasing.

It has led to pressure on operating theatres to switch to more environmentally-friendly gases.

NHS Highland said the shift to sevoflurane has cut its greenhouse gas emissions by an estimated 4.5%, as well as saving the health board £73,000 a year.

Since January, the consultants have reduced their use of desflurane at Raigmore Hospital to zero in favour of sevoflurane.

Read more: Nurse re-arrested over hospital deaths of eight newborn babies

Leading the charge is consultant anaesthetist Kenneth Barker.

He said: "To put the 4.5% reduction in context, all the hospital's heating and hot water produces about 10% of its CO2 equivalent emissions.

"An eight-hour operation using desflurane is the equivalent of 4,206 miles in an average car."

NHS Highland is the first NHS board in the UK to make desflurane special order only.

Mr Barker said: "Sevoflurane is clinically just as good... It's still a pollutant, but far less so.

"Desflurane is less potent than sevoflurane, so you had to use three times as much."

Mr Barker has recently been spreading the word to colleagues by giving talks during visits to London and Cardiff, and he and his colleagues are encouraging anaesthetists all over the country to follow their lead.

Read more: Consultant vacancies in NHS Scotland hit record high

Last year, NHS Highland accounted for just under 5% - 14,228 - of all the inpatient procedures which required patients to stay in hospital overnight. These are more likely to include cases where general anaesthetic has been used.

If the results at NHS Highland were replicated for similar operations at hospitals across Scotland, it could deliver savings in the region of £1.7 million.

However, the precise figure is hard to estimate as there are other gases in use besides desflurane, and the the savings would also depend on the duration of operations and patients case mix.

There are hopes for devices that can trap and recycle anaesthetic gases in future, but in the meantime Mr Barker said the NHS should avoid using desflurane.

He said: "I would get rid of desflurane entirely from the NHS for the next few years at least, as there is new technology coming along which aims to get rid of all anaesthetic agent pollution by capturing it in silicone meshes and recycling and reusing it."

The Raigmore anaesthetists are now pushing for the hidden environmental costs of drugs and supplies to become a routine part of assessing their suitability.

Dr Lucy Williams, sustainability lead for the Royal College of Anaesthetists, said both desflurane and sevoflurane were better for the environment that nitrous oxide - commonly known as laughing gas.

However, she added that gases in general had a bigger impact than liquid infusions.

She said: "Total intravenous anaesthesia is thought to have less impact than volatile [gaseous] anaesthesia.

"Nitrous oxide is 310 times more powerful as a greenhouse gas than carbon dioxide. It persists in the atmosphere for 114 years.

"Volatile agents also act as greenhouse gases, but to a lesser extent. For example desflurane is more damaging than sevoflurane.

"These newer agents enable delivery of volatile anaesthesia without nitrous oxide whilst still having a patient who wakes fairly quickly.”

It is understood that NHS National Procurement will encourage other health boards in Scotland to look at the NHS Highland example when buying their own anaesthetics.

It is up to health boards and prescribing clinicians to decide what to use for their patients.

A Scottish Government spokesman said: "We welcome NHS Highland’s innovative approach and expect all other Boards to look carefully at the evidence from NHS Highland to determine what more they can do in this area whilst maintaining patient safety.”