Volatile Anesthetics and Greenhouse Gases: Why Low-Flow Anesthesia is Necessary to Minimize Pollution Due to Anesthetic Waste

Within the past decade, many sectors have begun focusing on how they contribute to climate change, instituting significant operational changes in order to address this growing area of concern. One reason for this emphasis on combatting climate change, primarily within the healthcare sector, is due to the adverse health effects that result from global warming.¹ However, the healthcare sector itself remains a source of deadly pollution, from medical waste to greenhouse gases and other air pollutants.^{2, 3}

Volatile Anesthetics: What Are They?

Volatile anesthetics are potent greenhouse gases traditionally used for general anesthesia, offering an alternative to benzodiazepine-based sedation practices.

Examples of volatile anesthetics include:

• Sevoflurane
• Desflurane
• Nitrous oxide
• Isoflurane
• Halothane

While volatile anesthetics are not a new mechanism within healthcare, with a history that dates back more than 150 years, their increasing usage and applications within healthcare has resulted in a growing need to address these compounds' potentially harmful climate effects, namely in terms of medical waste and air pollution.⁴

Nitrous oxide and desflurane, in particular, have a greater impact on the environment and are used in clinically relevant quantities. For reference, the global warming potential of desflurane is 40-50 times that of isoflurane and sevoflurane, with nitrous oxide showing similar global warming impacts⁵ based on greenhouse gas emission effects. While addressing the environmental impact of all volatile anesthetics is important, there should be a greater emphasis on these two.

Furthermore, anesthetic gases are typically vented directly into the air without having any limit on pollution controls, which allows their ventilation to remain unchecked and further damage the environment.^{6, 7}

Initiatives for Sustainability

Knowing the impact of the healthcare sector on climate change, and the indirect detrimental impact climate change can have on harming a patient´s health, there have been recent initiatives to increase sustainability in the OR regarding volatile anesthetics. One of these initiatives is driven by the World Association of Anesthesiologists, which has placed a greater commitment on driving environmentally sustainable anesthesia.^{8, 9}

The American Society of Anesthesiologists has also compiled information regarding the environmental impact of volatile anesthetics and their recommendations for limiting this impact.¹⁰

They cite the motivation behind these recommendations on the estimation that 0.01-0.10% of the total global carbon dioxide equivalent (CO₂e) emissions contributing to global warming stem from inhaled anesthetic agents. Additionally, atmospheric sampling of volatile anesthetics shows that their accumulation in the atmosphere is increasing, creating a need for immediate interventions.

Recommendations by the American Society of Anesthesiologists include¹⁰:

• Avoiding anesthetics with high-climate impacts (e.g., nitrous oxide and desflurane)
• Prioritizing regional and intravenous anesthesia when appropriate
• Substituting and closing portable nitrous oxide canisters between uses

In addition to these recommendations, they also urge providers to use the lowest possible fresh gas flow rates for inhaled anesthetics.

Low-Flow Anesthesia and Its Implementation

One of the greatest ways that anesthetic gas waste can be minimized, thus limiting the influence of the healthcare sector on air pollution, is through consistent low-flow anesthesia practice.¹¹ In particular, this practice is most important upon induction of anesthesia, as that is when most gas waste production occurs¹² due to higher flow rates needed for the induction phase versus the maintenance phase of the case.

End-tidal Control Software

Despite the promise of low-flow anesthesia to limit environmental harm, there remain barriers and complexities that impede its more widespread usage, which must be overcome before its clinical practice becomes consistent.

However, technology is available to simplify the management of fresh gas flows and volatile agents, which is accomplished through advanced anesthesia systems equipped with automated anesthesia technology such as End-Tidal Control software.¹¹

With the automated control of end-tidal gases, End-tidal Control (EtC) software consistently reduced volatile agent consumption and greenhouse gas emissions, which aides in reducing the healthcare sector’s environmental impact.^{11, 13}

Conclusion

Volatile anesthesia is increasing in popularity within the healthcare sector due to its applications in sedation and general anesthesia. However, this increasing prominence, and the growing need to address the environmental impact of the healthcare sector, require interventions in this practice to limit medical waste as air byproducts.

Low-flow anesthesia offers one of the best ways to minimize environmental harm from anesthesia, and End-Tidal Control technology helps automate this control and makes it easier to limit greenhouse gas emissions.

References

1. Rossati, Antonella. “Global Warming and Its Health Impact.” The international journal of occupational and environmental medicine vol. 8,1 (2017): 7-20. doi:10.15171/ijoem.2017.963
2. Eckelman, M., & Sherman, J. (2016). Environmental Impacts of the U.S. Health Care System and Effects on Public Health. PLOS ONE, 11(6), e0157014. doi: 10.1371/journal.pone.0157014
3. Sherman, J. D., MacNeill, A., & Thiel, C. (2019). Reducing Pollution From the Health Care Industry. JAMA, 322(11), 1043–1044. https://doi.org/10.1001/jama.2019.10823
4. Jerath, A., Parotto, M., Wasowicz, M., & Ferguson, N. D. (2016). Volatile Anesthetics. Is a New Player Emerging in Critical Care Sedation?. American journal of respiratory and critical care medicine, 193(11), 1202–1212. https://doi.org/10.1164/rccm.201512-2435CP
5. Devlin-Hegedus, J. A., McGain, F., Harris, R. D., & Sherman, J. D. (2022). Action guidance for addressing pollution from inhalational anaesthetics. Anaesthesia, 77(9), 1023–1029. https://doi.org/10.1111/anae.15785
6. Sherman J, Le C, Lamers V, Eckelman M. Life cycle greenhouse gas emissions of anesthetic drugs. Anesth Analg. 2012 May;114(5):1086-90. doi: 10.1213/ANE.0b013e31824f6940. Epub 2012 Apr 4. PMID: 22492186.
7. Ryan, S. M., & Nielsen, C. J. (2010). Global warming potential of inhaled anesthetics: application to clinical use. Anesthesia and analgesia, 111(1), 92–98. https://doi.org/10.1213/ANE.0b013e3181e058d7
8. NHS Sustainable Development Unit. NHS England Carbon Footprint 2012. Available: http://www.sduhealth.org.uk/documents/publications/HCS_Carbon_Footprint…. Accessed 22 November 2015.
9. Principles of environmentally-sustainable anaesthesia: a global consensus statement from the World Federation of Societies of Anaesthesiologists S. M. White,1C. L. Shelton,2,3 A. W. Gelb,4 C. Lawson,5 F. McGain,6,7 J. Muret 8 and J. D. Sherman,9 representing the World Federation of Societies of Anaesthesiologists Global Working Group on Environmental Sustainability in Anaesthesia* doi:10.1111/anae.1559
10. Reduce Carbon Footprint from Inhaled Anesthesia with New Guidance Published . (2022). https://www.asahq.org/about-asa/newsroom/news-releases/2022/06/reduce-c…
11. Tay Financial and environmental costs of manual versus automated control of end-tidal gas concentrations S. Tay*, L. Weinberg†, P. Peyton‡, D. Story§, J. Briedis** Department of Anaesthesia, Northern Hospital, Melbourne, Victoria, Australia. Anaesth Intensive Care 2013; 41: 95-101
12. Kennedy RR, French RA, Vesto G, Hanrahan J, Page J. The effect of fresh gas flow during induction of anaesthesia on sevoflurane usage: a quality improvement study. Anaesthesia. 2019 Jul;74(7):875-882. doi: 10.1111/anae.14669. Epub 2019 Apr 29. PMID: 31032889.
13. Singaravelu S, Barclay P. Automated control of end-tidal inhalation anaesthetic concentration using the GE Aisys Carestation™. Br J Anaesth. 2013 Apr;110(4):561-6. doi: 10.1093/bja/aes464. Epub 2013 Jan 4. PMID: 23293274.

End-Tidal Control is indicated for patients 18 years of age and older in the US.

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