Guidance for Reducing the Carbon Footprint of Inhaled Anesthesia

Guidance published in Anesthesia, the official journal of the Association of Anaesthetists, offers actionable steps to mitigate the carbon footprint created from inhaled anesthetics comprising desflurane, often used in general anesthetics, and nitrous oxide — also known as laughing gas.

For several decades, anesthetic gases have drastically enhanced medical procedures by preventing pain and keeping patients comfortable. However, in the last 20 years, substantial evidence highlights inhaled anesthetics' undesirable environmental impacts.

Until last year, there had been insufficient progress in translating this data into actionable steps. While some hospitals and providers have already shifted their environmental outlook, the authors describe that more are considering it and desire guidance.

“Inhaled anesthetics are a significant contributor to healthcare-related greenhouse gas emissions. However, it is very achievable for the healthcare community to minimize their impact on the climate through intervention,” explained Jodi Sherman, MD, co-author, chair of the American Society of Anesthesiologists’ Committee on Environmental Health, and associate professor of anesthesiology at Yale School of Medicine. “The guidance summarizes the latest actions healthcare professionals involved in the administration of inhaled anesthetics can take to mitigate greenhouse gas emissions, while maintaining quality outcomes and patient safety, and potentially saving costs.”

Anesthesiology, a carbon-intensive specialty, involves the routine use of volatile anesthetic agents that are highly potent greenhouse gases, such as nitrous oxide and halogenated inhalational anesthetics, including isoflurane, sevoflurane, and desflurane. This process releases these environmentally harmful gases into the atmosphere, continually exacerbating the climate crisis and threatening public health.

Some researchers estimate that volatile anesthetic agents are responsible for 0.01–0.10% of the total global carbon dioxide equivalent emissions contributing to climate change. Still, the lowest estimate ignores all dental, veterinary, and laboratory medicine use. Because of this, other researchers suggest that the contribution of inhaled anesthetics is much higher. As indicated by an atmospheric sampling of volatile anesthetics, their chemical accumulation is increasing. 

In high-income countries, inhaled anesthetics account for 5% and 50% of acute hospital carbon dioxide and perioperative department emissions, respectively.

In general anesthesia, chemical compounds such as desflurane, sevoflurane, isoflurane, halothane, and nitrous oxide are commonly used. While the environmental impacts of all these agents should be a primary concern, nitrous oxide and desflurane are several times greater in clinically relevant quantities.

The authors wrote that the global warming potential of desflurane, scaled by clinical potency, is roughly 40–50 times that of sevoflurane and isoflurane over a 100-year period.

Significantly more expensive than other volatile anesthetics, desflurane has little clinical benefit that justifies its use. Avoiding its use may have a cost savings benefit. 

Because nitrous oxide is less potent than other inhaled anesthetics, it must be used in high concentrations and has a very long atmospheric life. In clinically relevant doses, nitrous oxide’s global warming impacts are similar to desflurane.

The authors created a clinical action template to produce the guidance document template, which was obtained from Coda — a medical education and health promotion charity that provides achievable and sustainable actions to reduce the healthcare industry’s carbon footprint and distills mitigation actions supported by scientific evidence.

The evidence-based recommendations for providers include the following:

• avoid inhaled anesthetics with disproportionately high climate impacts, such as desflurane and nitrous oxide
• select the lowest possible fresh gas flow setting when using inhaled anesthetics
• prioritize regional and intravenous anesthesia when appropriate to lessen the environmental impact of inhaled anesthetics
• substitute nitrous oxide with closable, portable canisters to avoid continuous leaks, as the majority of this gas is lost and released into the air through leaks in central piping systems
• optimize research before investing in the use of technological solutions for capturing or destroying inhaled anesthetic waste

Additionally, the guidance provides methods to measure and review progress and share success.

“Considering the impact that inhaled anesthetics have on the climate and with the practical, evidence-based interventions we have relayed, we are hopeful our guidance document contributes to the much-needed global transition toward environmentally sustainable anesthesia,” said Jessica Devlin-Hegedus, MD, lead author and consultant, Department of Anesthesia, Wollongong Hospital. “Nitrous oxide is commonly used by non-anesthesia providers as well, such as in the labor suite, dental offices, and emergency care. We are working to educate diverse groups of health professionals on the deleterious impact inhaled anesthetics have on the environment and to consider safe, environmentally preferable alternatives.”