Are You Green Enough? Embracing Sustainability in Anesthesia
Veronica Zoghbi, MD and Germana Silva, MD and the SPA SIG for Sustainability
I (GS) am a pediatric anesthesiologist practicing at Nemours Children’s Health, Florida. I finished my fellowship in 2015 and I still consider myself to be a youngster. However, the concept that anesthesia gases are Greenhouse Gases (GHG) was never taught to me during training. I remember the Society for Pediatric Anesthesia (SPA) Fall Meeting in 2019 when Dr. Diane Gordon gave a lecture on reducing the environmental impact of anesthesia. It was extremely eye opening! What have I been doing?
Fast forward to March of 2021. I joined the SPA Special Interest Group (SIG) for Sustainability and founded the Perioperative Sustainability Committee at Nemours. By September of 2021, we agreed as a group to eliminate desflurane from the hospital.
Dr. Veronica Zoghbi is a pediatric anesthesiologist who is actively involved in sustainability projects at Stanford University and LucilePackard Children’s Hospital. Veronica began her sustainability journey during her early training. She implemented and became the Project Leader for a Perioperative Surgical Supplies Recovery Program at the Hospital of the University of Pennsylvania.
But why is this important? Why should pediatric anesthesiologists care? Today’s Pediatric Anesthesia Article of the Day help answer these questions.
PS from Myron: Today’s PAAD once again reminds all of us and demonstrates the power of being a member of the Society for Pediatric Anesthesia, attending its annual meetings, and joining its committees and special interest groups. If you haven’t done it already please consider following the link below and registering for the fall meeting in San Francisco.
https://www2.pedsanesthesia.org/meetings/2023annual/guide/reg/index.iphtml?_ga=2.261129613.1627475843.1689181027-867344887.1647626644&_gl=1*1bi9e3c*_ga*ODY3MzQ0ODg3LjE2NDc2MjY2NDQ.*_ga_MZLG20V6K8*MTY4OTE4MTAyNy4xNi4xLjE2ODkxODEwMzAuMC4wLjA.
Original Article
Ahn, J; Bennici, L; Costa, A. “The Gas Looks Greener on the Other Side: Using Novel Tech to Minimize Anesthesia Greenhouse Emissions.” ASA Monitor. June 2023. 24.
The article effectively summarizes how our healthcare sector, in particular how volatile anesthetics, contribute to the creation of waste and greenhouse gas emissions. Ahn and colleagues highlight the key facts on volatile anesthetics’ carbon footprint and recommendations to avoid pollution. These medications undergo minimal in vivo metabolism and are exhaled essentially unchanged. They are collected via the scavenger system and vented directly into the atmosphere as waste anesthetic gases (WAGs). These medical gases remain in the atmosphere for extended periods. Desflurane remains for 14 years, isoflurane for 3.2 years, and sevoflurane for 1.1 years.1 The Global Warming Potential (GWP) definition was developed to allow comparisons of the global warming impacts of different greenhouse gases. Specifically, it is a measure of how much energy the gas will absorb over a given period (20 or 100 years), relative to the same amount of carbon dioxide (CO2), which by definition has a GWP value of 1. The higher the GWP, the more heat the gas traps in the atmosphere compared to CO2.2 The one hundred-year GWP values for inhaled anesthetics are sevoflurane 130, isoflurane 550, desflurane 2250, and nitrous oxide (N2O) 265.3-5 The key point of this complicated information is that volatile anesthetics are more potent as greenhouse gases than CO2 and they contribute to global warming.
WAGs are estimated to make up approximately 50% of perioperative GHG emissions, 5% or more of total hospital GHG emissions, and can account for 3% of national health care sector GHG emissions.2 Desflurane accounts for approximately 80% of estimated GHG effect from volatile anesthetic waste.6 N2O is the second most harmful inhalational agent after desflurane. This is due to its low potency and high concentrations requirement for clinical effect, its atmospheric lifetime of over one hundred years, its potent ozone depleting effects7 and the evidence that 95% of it leaks out of central delivery systems before clinical use8,9. Ryan et al. calculated that 1 minimal alveolar concentration (MAC)-hour at 1-2 L of fresh gas flow (FGF) of desflurane equates to the automobile emissions of driving 235-470 miles, while 1 MAC-hour of isoflurane (1-2 L FGF) and sevoflurane (2 L FGF) are equivalent to driving 20-40 miles and 18 miles, respectively.10 The higher you keep your FGF, the greater number of miles you are driving your car. This is particularly important for pediatric anesthesiologists since we commonly perform inhalational induction with unnecessarily high FGF, may use N2O for induction, and do mask cases.
What can we do about it today and in the future?
The authors mention current recommendations for mitigating WAG pollution including utilizing low FGF, avoiding, or really eliminating, desflurane and N2O, considering total intravenous anesthesia (TIVA) and regional anesthesia, decommissioning central pipeline systems for N2O, and using portable N2O canisters that can be closed off between uses. Recently, environmental technologies have been developed to minimize, treat, or reuse WAGs. Automated control of end-tidal anesthetic gas concentration and electronic record alerts to decrease FGF have decreased GHG emissions. Technology for destroying N2O is gaining traction in other countries. Finally, gas capture systems to recycle and reuse volatile anesthetics already exist and are used across Canada, Europe, and the United Kingdom. Authors mentioned CONTRAfluran™ by Zeosys and Baxter and the Deltasorb® and Centralsorb® systems by Blue-Zone Technologies as gas capture systems used routinely in other countries. At Stanford, Class I Gas Capture11 is used. This is a patented system that captures 99.9% halogenated drugs from the anesthetic gas scavenging system. These gases are compressed, dried, sterilized, and captured on Halosorb™ in sealed tanks. This waste is sent to Canada where a unique desorption and condensation process converts gas to liquid. The liquid anesthetics are stored in tamper-proof containers and are being used for research on how to efficiently repurpose or destroy them11.
As professionals dedicated to patient care and safety, we must recognize our carbon footprint in the perioperative setting. It is within our power to choose practices that align with environmental sustainability. By embracing environmentally friendly anesthesia techniques we can mitigate our contribution to greenhouse gas emissions and foster a healthier future for our planet and the patients we serve. Let us step up together, seize the opportunity to make a difference, and ensure that our legacy as anesthesia providers transcends care of individual patients and encompasses environmental stewardship.
PS from Myron: We have many readers in the U.K. and Europe. Are you using these gas capture systems in the OR or are they being used primarily in the ICUs? Send your responses to me and I will post in the Friday Reader Response.
References
1. Andersen, Mads P. Sulbaek PhD*; Nielsen, Ole J. PhD†; Wallington, Timothy J. PhD‡; Karpichev, Boris PhD*; Sander, Stanley P. PhD*. Assessing the Impact on Global Climate from General Anesthetic Gases. Anesthesia & Analgesia 114(5):p 1081-1085, May 2012. | DOI: 10.1213/ANE.0b013e31824d6150
2. United States Environmental protection Agency. Understanding Global Warming Potentials. Last updated, April 18th, 2023. Link: https://www.epa.gov/ghgemissions/understanding-global-warming-potentials
3. Sulbaek Andersen M.P., Nielsen O.J., Karpichev B., Wallington T.J., Sander S.P. Atmospheric chemistry of isoflurane, desflurane, and sevoflurane: kinetics and mechanisms of reactions with chlorine atoms and OH radicals and global warming potentials. J Phys Chem A. 2011;116:5806–5820.
4. Sulbaek Andersen M.P.S., Nielsen O.J., Wallington T.J., Karpichev B., Sander S.P. Assessing the impact on global climate from general anesthetic gases. Anesth Analg. 2012;114:1081–1085.
5. Tignor K., Allen M., Boschung S.K., et al. 2013. IPCC (Intergovernmental Panel on Climate Change). The physical science basis. Contribution of working group I to the fifth assessment report of the intergovernmental panel on climate change; p. 1535.https://www.ipcc.ch/report/ar5/wg1/ Sherman J D, Chesebro B B. Inhaled anaesthesia and analgesia contribute to climate change. BMJ 2022; 377 :o1301 doi:10.1136/bmj.o1301
6. McGain, Forbes et al. Environmental sustainability in anaesthesia and critical care. British Journal of Anaesthesia, Volume 125, Issue 5, 680 – 692.
7. A. R. Ravishankara, et al., Nitrous Oxide (N2O): The Dominant Ozone-Depleting Substance Emitted in the 21st Century. Science326,123-125(2009). DOI:10.1126/science.1176985
8. Seglenieks R, Wong A, Pearson F, McGain F. Discrepancy between procurement and clinical use of nitrous oxide: waste not, want not. Br J Anaesth. 2022;128(1):e32-e34. doi:10.1016/j.bja.2021.10.021
9. Chakera A. Driving down embedded emissions from medical nitrous oxide. BMJ. 2021 Nov 26;375:n2922. doi: 10.1136/bmj.n2922. PMID: 34836914.
10. Ryan SM, Nielsen CJ. Global Warming Potential of Inhaled Anesthetics: Application to Clinical Use. Anesthesia & Analgesia. 2010;111(1):92-98. doi:10.1213/ANE.0b013e3181e058d7
11. Class 1 Inc building Better Healthcare. https://www.class1inc.com/halogenated-drug-recovery-/266w2w5w11w63