Choice of anaesthetic gas is a significant contributor to emissions, particularly in North American hospitals using desflurane, instead of cheaper, low-carbon alternatives.

The first analysis of the carbon footprint of surgical suites at three hospitals in the UK, Canada and the USA highlights that the choice of anaesthetic gases used in surgery can be a major contributor to greenhouse gas emissions from operating theatres.

The study, published in The Lancet Planetary Health journal, highlights the potential for reducing emissions in health care settings and at the same time potentially reducing costs.

The health sector is one of the largest service industries, with a considerable carbon footprint. In the USA, the health care system generates 8-10% of all greenhouse gas emissions. In the UK, the National Health Service is responsible for 25% of public sector emissions.

The new study measured the carbon footprint of three surgical suites in Canada (Vancouver General Hospital), the USA (University of Minnesota Medical Centre) and the UK (John Radcliffe Hospital, Oxford). The researchers measured direct emissions (eg, volatile gases), indirect emissions (eg, electricity consumption), and other emissions (eg surgical waste), according to the Greenhouse Gas Protocol. Data were collected for each source and evaluated during 2011.

The annual carbon footprint of surgical suites ranged from approximately 3218 tonnes of CO 2 equivalents (CO 2 e) to 5187 tonnes of CO 2 e. While there were differences in the size and case load among all three surgical suites, there was also wide differences in the major contributors to greenhouse emissions. For instance, at Vancouver and Minnesota, anaesthetic gases were responsible for 63% and 51% of the total surgical emissions, compared to only 4% at Oxford.

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Emissions due to anaesthetic gases accounted for approximately 2000 tonnes of CO 2 e at each North American site -- ten-fold higher than the anaesthetic gas emissions from the UK hospital. The authors say this is largely the result of a higher usage of desflurane in the two North American hospitals. Desflurane has a high global warming potential (GWP), approximately 5 to 18 times higher than other anaesthetic gases, such as isoflurane and sevoflurane. It is also expensive, accounting for 83-86% of the cost of volatile agents at the two North American hospitals.

Dr Andrea MacNeill, Vancouver General Hospital, BC, Canada, and lead author of the study says: "Not only is desflurane a primary contributor to global anaesthetic gas emissions, it is also one of the most expensive anaesthetic gases. One of the greatest barriers to widespread implementation of low-carbon practices is the lack of awareness regarding the environmental impacts of anaesthetic choices. The climate impacts of surgery are generally accepted as necessary for the provision of quality care, but our study shows that it's possible to reduce the carbon footprint of surgery, which also reduce costs, without compromising patient care."

Due to the building standards of operating theatres, heating, ventilation, and air conditioning made use up 90-99% of overall theatre energy (compared to 52% in general inpatient health-care facilities).

In Oxford, energy consumption was responsible for 84% of site emissions, compared to 17% in Vancouver and 36% in Minnesota. The authors say that reducing heating, ventilation and air conditioning in theatres overnight and at weekends, while leaving a minimum number of theatres online for emergencies, could significantly reduce emissions.

The average emissions per operating theatre, based on this study, were 188 tonnes of CO 2 e per theatre per year. Assuming the hospitals studied were representative of their respective regions, extrapolating these results to the number of operating theatres in the UK, USA and Canada would yield a total carbon footprint estimated at 9.7 million tonnes of CO 2 e per year, equivalent to 2 million passenger vehicles.

The study did not include emissions involved in the manufacture, sterilisation or transport of surgical items (including pharmaceuticals) so the study likely underestimates the emissions.

Writing in a linked Comment, Dr Tim Taylor, University of Exeter Medical School (UK) and Phil Mackie, Scottish Public Health Network (UK) say: "There exists a need for a better understanding of climate change and mitigation in the health sector. Carbon footprinting studies are just a first step. Options need to be evaluated in terms of their cost-effectiveness and many could be win-win in terms of energy savings. Better decision making around carbon is needed at all levels; from decisions about the location of health services by high level managers to even everyday decisions on the choices of what to put on the menu in the hospital canteen. Understanding the carbon footprint of health care involves everyone in that system; from the patients to the managers, from the porters to the surgeons. Patient care is obviously paramount, but carbon management can no longer be ignored. Shared learning across institutions and across international borders is needed; the lessons drawn from critically comparing management practices, building designs, and care pathways in terms of carbon intensity might lead to a more critical approach overall."