Over the past two decades, substantial evidence has emerged on the environmental footprint inhaled anesthetics have, but there has been insufficient progress to translate this information into actional steps to mitigate the problem. While some hospitals and providers have made environmental improvements, more are considering it and require direction, the authors report.
“Inhaled anesthetics are a significant contributor to health care-related greenhouse gas emissions. However, it is very achievable for the health care community to minimize their impact on the climate through intervention,” said Jodi Sherman, M.D., co-author, chair of the American Society of Anesthesiologists’ Committee on Environmental Health, and associate professor of anesthesiology at Yale School of Medicine, New Haven, Connecticut. “The guidance summarizes the latest actions health care 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 is a carbon-intensive specialty, involving the routine use of inhaled agents that are potent greenhouse gases. These gases are exhausted directly to the atmosphere, contributing to global warming. Inhaled anesthetic agents have been estimated to be responsible for 0.01-0.10% of the total global carbon dioxide equivalent (CO2e) emissions contributing to global warming. Based on atmospheric sampling of volatile anesthetics, their accumulation is increasing. Inhaled anesthetics account for 5% of acute hospital CO2e emissions and 50% of perioperative department emissions in high-income countries.
Relevant inhaled volatile anesthetics include desflurane, sevoflurane, isoflurane, and halothane, which are used in general anesthesia, as well as nitrous oxide. While the environmental impacts of all these agents should be mitigated, desflurane and nitrous oxide are several times greater in clinically relevant quantities, making them an even greater priority for intervention. In fact, the global warming potential of desflurane, scaled by clinical potency, is approximately 40-50 times that of sevoflurane and isoflurane over a 100-year period, the authors note. Desflurane is also significantly more expensive than other volatile anesthetics, with little evidence of clinical benefit justifying its use, and avoiding its use may have a cost savings benefit. Nitrous oxide is less potent than other inhaled anesthetics and must be used in high concentrations. It has a very long atmospheric life and its global warming impacts are similar to desflurane in clinically relevant doses.
The authors used a clinical action template to develop the guidance document. The template was obtained from Coda, a medical education and health promotion charity that seeks to provide achievable and sustainable actions to reduce health care’s carbon footprint, and provides individual action templates, authored by small groups of clinical experts, to distill mitigation actions supported by scientific evidence.
The evidence-based recommendations provided in the guidance document include:
- Providers should avoid inhaled anesthetics with disproportionately high climate impacts, such as desflurane and nitrous oxide.
- The lowest possible fresh gas flow should be selected when using inhaled anesthetics.
- Regional anesthesia and intravenous anesthesia should be prioritized and used when appropriate, since they have less of a negative environmental impact.
- The majority of nitrous oxide is lost, pre-use, and released into the air though leaks in central piping systems that should no longer be used. Portable canisters should be substituted and closed between uses to avoid continuous leaks.
- More research is needed before recommending investment in the use of technological solutions for capturing or destroying inhaled anesthetic waste, and they should not be considered high mitigation priorities.
The document also includes guidance on how to measure and review progress, along with a means to share successes.
“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, M.D., lead author and consultant, Department of Anesthesia, Wollongong Hospital, NSW, Australia. “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.”
THE AMERICAN SOCIETY OF ANESTHESIOLOGISTS
Founded in 1905, the American Society of Anesthesiologists (ASA) is an educational, research and scientific society with more than 55,000 members organized to raise and maintain the standards of the medical practice of anesthesiology. ASA is committed to ensuring physician anesthesiologists evaluate and supervise the medical care of patients before, during and after surgery to provide the highest quality and safest care every patient deserves.
For more information on the field of anesthesiology, visit the American Society of Anesthesiologists online at asahq.org. To learn more about the role physician anesthesiologists play in ensuring patient safety, visit asahq.org/madeforthismoment. Like ASA on Facebook and follow ASALifeline on Twitter.
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