A study performed at Michigan Medicine reveals that the use of less polluting inhaled anaesthetic agents reduced harmful emissions by 50% in one year without impacting patient safety or outcomes.
“Inhaled anaesthetics are a natural area to pursue reductions in emissions because, as greenhouse gases, they are so disproportionately bad for the environment,” said Douglas Colquhoun, assistant professor of anaesthesiology at U-M Medical School.
“We’ve shown that small changes in our practice lead to big changes for the environment and, importantly, no changes for the patients.”
The findings culminate from The Green Anaesthesia Initiative, launched at Michigan Medicine in March 2022 aimed to reduce the use of nitrous oxide, use less environmentally harmful inhaled fluorinated ethers, and increase the use of intravenous anaesthetics.
The team compared the output of CO2 equivalents, traditionally used to measure the effect of greenhouse gases on the environment, as well as the amount of anaesthetic used and patient outcomes such as post-surgery nausea and vomiting, pain scores, and unintended awareness and recall of the surgery.
As part of the initiative, the department encouraged providers to reduce the use of nitrous oxide (which is 270 times more potent than carbon dioxide at warming the environment), as well as increase the use of sevoflurane, the least environmentally harmful ether, instead of isoflurane. These changes were associated with an average decrease of more than 14 kg per case in CO2 equivalents. There were no changes in measured depth of anaesthesia, pain scores, or postoperative nausea and vomiting.
“I think the important thing that we showed was that it is possible to significantly reduce the environmental impact of anaesthesia. Even beyond the study period, we reduced our emissions by a huge amount in under three years.
“We did this while modernising our care and improving safety for patients. This is a great example of where mindful choices, technology and education all come together to make care better for our patients – both directly in the OR and in the environment in which we all live,” said David Hovord, clinical assistant professor of anaesthesiology.
“Our individual and team efforts to save the planet are essential. The carbon emissions reduction accomplishments of anaesthesiology and support teams are a point of pride at Michigan Medicine, as they are a demonstration of creativity, persistence and teamwork,” said Tony Denton, Michigan Medicine's senior vice president and chief environmental, social and governance officer.
“These impressive results show that we can redesign our long standing approaches to care without compromising patient safety, quality and outcomes. This is a great example of what we can do to reduce environmental harm and improve public health across the communities and society we serve,” he said.
The paper is published in Lancet Planetary Health, DOI: 10.1016/S2542-5196(24)00331-0
