Kalmar, Alain

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Ghent University Academic Bibliography

W H I T E  PA P E RThis document is intended to provide information to an international audience outside of the US.Anesthesia and climate change Why anesthetists should careThe environmental footprint of  anesthetic agentsGreenhouse gases are the main drivers of climate change.  Anesthesia practice and contemporary technologies can  help anesthetists reduce anesthetic waste to minimize the negative impact on our environment.Author: Dr. Alain F Kalmar, MD, PhDW H I T E  PA P E R2First, do no harmReducing our environmental impact can protect both patients and planet, and save moneyHuman activity is drastically changing our atmosphere1,  and anesthetic agents contribute to climate change.4 By implementing relatively simple changes in choice of anesthetic agent or ventilator settings, every individual anesthetist can make a difference for our planet.1. ... probability that greenhouse  gases have caused increases in  the Earth’s temperature.1 >95%Experts agree:  human activity is changing  our planet1The Earth is becoming warmer overall. The 10 hottest years ever recorded have occurred since 1998, with seven of the 10 occurring between 2010–2017.2 This temperature increase is resulting in a dramatic change in ecosystems, leading to unpredictable weather patterns, devastating storms, biodiversity loss, long-term droughts, wildfires, and desertification.The Intergovernmental Panel on Climate Change, operat-ing under the authority of the United Nations, identified human-caused emissions as the primary source of increases in atmospheric greenhouse gases. These levels have increased by more than 40% in the last 150 years.1 How do anesthetic agents contribute to climate change? Modern anesthetic agents are potent greenhouse gases. In typical use, less than 5% of the total delivered halogen-ated anesthetic is metabolized by the patient; the remain-der is routinely vented into the atmosphere through the operating room scavenging system.3 Two main attributes determine the global warming  potential (GWP) of a volatile agent: the atmospheric half-life, and the potency of the agent to capture infrared light in addition to the natural greenhouse gases. There is a  significant divergence in each agent’s global warming effects due to differences in heat-trapping capacity  and atmospheric half-life. W H I T E  PA P E R 3The global warming potential ofa halogenated anesthetic is up to 3,700 times greater than CO₂.4 Molecule GWP (100y)CO₂ 1CH₄ 28N₂O 296Isoflurane 350Sevoflurane 575Desflurane 1526SF₆ (sulfur hexafluoride) 23,500Compound Lifetime (y)Sevoflurane 1.2Isoflurane 3.6Desflurane 10Nitrous oxide 114Table 3: Tropospheric lifetime  of inhaled anesthetics4Table 1: Atmospheric record of halogenated anesthetics.Red line: Northern hemisphere. Blue line: Antarctica 5Table 2: Global Warming Potential (GWP)3Halothane and isoflurane are halogenated chlorofluoro-carbons (CFC) while sevoflurane and desflurane are hydro-fluorocarbons (HFC), all known as high-GWP gases. These gases have GWP numbers in the hundreds or thousands.4 This means that for their mass, they trap hundreds to thousands of times more heat than CO₂, which is the baseline by which all other emissions are measured.6By definition, the GWP of CO₂ is 1. In comparison, 1 kg  of nitrous oxide (N₂O) has a GWP of 296, the same heat trapping effect as 296 kg of CO₂ (Table 2).The atmospheric concentrations of anesthetic gases  – particularly desflurane – are rapidly increasing (Table 1).7There are dramatic differences in the length of time that these gases remain in the atmosphere. While sevoflurane clears from the atmosphere relatively quickly, N₂O emitted today remains in the atmosphere for more than 100 years, on average (Table 3).6 Anesthetic gases are typically excluded from environmen-tal agreements because of their medical necessity. None-theless, the effects of anesthetic agents are significant. The anesthesia practice in an average midsize hospital has an environmental effect comparable to that of up  to 1,200 cars per year.8Desflurane [ppt]Sevoflurane  [ppt]W H I T E  PA P E R4Other factors that determine the climate  effects of anesthetic agentsVentilator settings also dictate the amount of volatile  anesthetic waste. The combined effect of agent choice and ventilator setting results in a strikingly divergent environmental impact for an equal depth of anesthesia. The heat-trapping effects of eight hours of volatile anes-thetic use is comparable to driving an average car between 100–13,000 km (60–8,000 miles), depending on the choice of volatile agent and ventilator setting.Using another comparator: In a timeframe of only 5 days  of anesthesia of 8 hours per day with 1 MAC sevoflurane at 2 L FGF, an anesthetist emits an equivalent of 280 kg CO₂. The same period with 1 MAC desflurane at 6 L FGF emits 16,000 kg of CO₂ equivalent. As such, an anesthetist can unknowingly emit in one week as much CO₂ equivalents through volatiles alone as an average US citizen emits  in a whole year. 4Some anesthetic gases also damage  the ozone layerIn addition to greenhouse effects, some volatile anesthe-tics also have the capability to deplete the ozone layer.CFCs, such as halothane or isoflurane, eventually reach the upper stratosphere into the ozone layer. When a CFC  is hit by an ultraviolet (UV) photon from sunlight, a free chlorine radical is released. The chlorine acts as a catalyst to turn ozone (O3) into oxygen (O₂), after which the chlo-rine radical is regenerated. This cycle can be repeated millions of times, and as such, a single CFC molecule can destroy millions of ozone molecules before the chlorine radical is finally neutralized. 80% of all stratospheric ozone depletion is attributed to released CFCs. Sevoflurane and desflurane lack chlorine atoms, and have therefore no  effects on the ozone layer. 17*8h/day at a Fresh Gas Flow (FGF) of 2 L. 4,82 weeks of  desflurane use* equals driving  a car around  the globe!W H I T E  PA P E R 5Anesthetic FGF (L/min) Grams/hour GWP₂₀ CDE₂₀ (g/h) Ratio₂₀ CDE2% sevoflurane 2 20.0 349 6980 11.2% isoflurane 0.5 2.8 1401 3881 0.61 5.5 1401 7762 1.12 11.1 1401 15,551 2.26 % desflurane 0.5 12.6 3714 46,796 6.71 25.2 3714 93,593 13.42 50.4 3714 187,186 26.8Table 4 shows that one hour  of sevoflurane at 2% with a fresh gas flow of 2 L/min emits a heat trapping effect equal to almost  7 kg of CO₂. In contrast, one hour of desflurane at 6% with the same FGF of 2 L, emits a heat trapping effect equal to almost 187 kg  of CO₂.8The impact of greenhouse gas emissions from anesthetic agents can easily be reduced significantly by adhering to a few basic principles. These changes can be made without risking patient safety.Change the anesthetic agentNot all anesthetic agents have the same GWP nor are  they used equally. Because both the MAC and the intrinsic GWP dictate the ultimate effect, desflurane has a 26-fold effect as sevoflurane for an equal level of anesthesia with an equal FGF. As such, one hour of anesthesia at equal ventilator settings and depth of anesthesia with desflu-rane emits the same amount of heat trapping effect as  26 hours of anesthesia with sevoflurane.4 Replacing desflurane with sevoflurane is therefore an obvious first step that can dramatically reduce any anesthetist’s greenhouse gas emissions.Reducing fresh gas flow to reduce consumptionMinimizing the fresh gas flow will decrease the consump-tion of volatile anesthetics and their emission in the  atmosphere. In low-flow anesthesia – conventionally  defined as a fresh gas flow of less than 1.0 L/min – a re-breathing system uses less anesthetic agent than open systems. Such settings emit less gas into the atmosphere, and improve the flow dynamics of the inhaled air.Reducing the fresh gas flow (FGF) during general anesth- esia is a simple strategy that leads to cost savings from reduced consumption of volatile anesthetics.9 Lower fresh gas flows can be achieved by manual adjustments of the gas settings, or by using an automated gas  control function. It’s clear that the impact of anesthetic agents is significant. Lacking a standardized global approach, improving awareness of the impact any  individual anesthetist can make, is an essential first step to dramatically reducing the emissions from the anesthesia sector. How can we reduce the impact of  anesthetic gases on climate change?Table 4: Global warming impact of one hour of volatile agent useW H I T E  PA P E R6Low-flow anesthesia with automated gas controlAn automated gas control function automatically  adjusts FGF and agent concentration to reach set end- tidal targets for anesthetic agent (EtAA) and inspired O₂. This permits a combination of extremely stable levels of end-tidal volatile concentration with minimal consump-tion. The system automatically ensures the desired target values for inspired oxygen and EtAA, while efficiently limiting wastage. It provides simultaneously a large reduc-tion in the consumption of anesthetic agent and a completely controlled and stable administration of vola-tile anesthetics, permitting both maximal patient safety and volatile agent conservation.10  In addition, even in high fresh gas flow setting, some of these modern ventilators will automatically restrict the fresh gas flow to the minute volume, and as such limit wastage even in the open  flow setting.Advantages of automated gas controlAutomated gas control reconciles safe and efficient  induction and maintenance of anesthesia with minimized agent wastage.Automated gas control guarantees a secure combination of stable volatile administration levels with minimal flow without the need for constant adjustments of the ventila-tor settings, improving workflows. A study comparing manual-controlled low-flow anesthesia to automatic- controlled delivery showed that 244 adjustments were  required in manual mode to reach and keep adequate  anesthesia levels compared to zero when using auto- mated gas control.11 Automated control of gases also reduces the risk of  hypoxic mixtures or inappropriate depth of anesthesia and ultimately promotes patient safety.10A higher fraction of rebreathing will also:• improve the flow dynamics of inhaled gases.• increase mucociliary clearance.• maintain body temperature and reduce water loss.Significant cost savings with lower flowsThe cost of anesthetic agent accounts for a large portion of the total cost of ownership (TCO) for anesthesia machines. Implementation of a low-flow strategy easily permits a reduction in consumption of volatile anesthetics by 25–50% compared to conventional fresh gas flow (2L–4L/min), while providing a more stable level of FiAA and FiO₂ if using automated gas control.8 With an average of 10 anesthesia devices running 2000 hours/year, this would account to a reduction of 170,000 to 680,000 ml/year.8,13 At an estimated price of 0.50 $/ml, this represents a saving of $85,000 to $340,000/year.*Hospitals have reported significant agent reductions  by changing  to a low-flow strategy using automated gas control (AGC), many between 30 –42 %.12 This results in  significant cost savings, as well as dramatic reductions  in environmental impacts.One doesn’t really appreciate how  thin the atmosphere is, to what extent  we are capable of destroying the planet  – to what extent we need to protect it. Thomas Pesquet, Astronaut, European Space Agency (ESA)Cost saving/year*$ 340,000W H I T E  PA P E R 7Simple actions to limit your  hospital’s ecological  impact from anesthetics1. Minimize desflurane usage Keeping all parameters equal, but changing the agent from desflurane to sevoflurane can reduce your environmental impact by as much as 96%.142. Use low-flow anesthesia when possible  Lower fresh gas flows (FGF), preferably with an  automated gas control, greatly reduce agent  consumption, delivering positive outcomes for  patients, hospital spending, and the environment. 3. Avoid spills  It may sound obvious, but avoiding spills  of liquid volatiles can reduce a facility’s  environmental footprint. 4. Avoid using nitrous oxide  Nitrous oxide is used in higher concentrations than other anesthetic agents and has an extremely long atmospheric half-life. Limiting use of N₂O can dra-matically reduce greenhouse gas emissions.15,16In summary, there are easy ways to reduce your facility’s  environmental footprint without compromising patient safety.  By choosing environmentally responsible agents and delivery modes, each anesthetist can reduce their environmental impact at a level equivalent to the total emissions of 1 to 50 average US citizens.Adherence to these few basic principles can result in a 99% reduction in greenhouse gas emissions while preserving the convenience and advantages of volatile anesthesia.Getinge is a global provider of innovative solutions for operating rooms, intensive care units, sterilization  departments and for life science companies and institutions. Based on our firsthand experience and close  partnerships with clinical experts, healthcare professionals and medtech specialists, we are improving the  everyday life for people – today and tomorrow.   This document is intended to provide information to an international audience outside of the US.Manufacturer · Maquet Critical Care AB · 171 54 Solna, Sweden · Phone: +46 (0)10-335 00 00 · info@getinge.comwww.getinge.com ©Maquet Critical Care AB 2018, MX-7414 Rev03 English.1. http://ipcc.ch/pdf/assessment-report/ar5/syr/AR5_SYR_FINAL_SPM.pdf, http://www.ipcc.ch/2. “Global Climate Report – Annual 2017”. NOAA. Retrieved 18 January 20183. Gadani H, Vyus A. Anesthetic gases and global warming: Potentials, prevention and future of Anesthesia.  Anesth Essays Res. 2011; 5:  5–10.4. Sulbaek Anderson MP, Sander SP, Nielsen OJ, et al.  Inhalation anaesthetics and climate change. Br J Anaesth. 2010;105:760-766.5. Vollmer MK, Rhee TS, Rigby M, et al. Modern inhalation anesthetics: Potent greenhouse gases in the global atmosphere. Geophys Res Lett. 2015;42:1606-1611. 6. EPA.gov 7. Charlesworth M, Swinton F. Anaesthetic gases, climate change, and sustainable practice. The Lancet. 2017;1:e216-e217.8. Ryan SM, Nielsen CJ. Global Warming Potential of Inhaled Anesthetics: Application to Clinical Use. Anesth Analg.  2010; 11: 92-98. 9. Epstein RH, Dexter F, Maguire DP, et al. Economic and Environmental Considerations During Low Fresh Gas Flow Volatile Agent Administration After Change to a Nonreactive Carbon Dioxide Absorbent. Anesth Analg. 2016;122:996–1006. 10. Tay S, Weinberg L, Peyton P, et al. Financial and environmental costs of manual versus automated control of end-tidal gas concentrations. Anaesth Intensive Care 2013; 41: 95-101.11. Lucangelo U, Garufi G, Marras E, et al. End-tidal versus manually-controlled low-flow anaesthesia. J Clin Monit Comput. 2014; 28: 117-121.12. AGC greatly reducing anesthetic agent usage, Getinge case studies, MX-6599 rev05.13. Laster MJ1, Fang Z, Eger EI 2nd. Specific gravities of desflurane, enflurane, halothane, isoflurane, and sevoflurane. Anesth Analg. 1994; 78: 1152-1153. 14. Yasny JS, White J. Environmental implications of anesthetic gases. Anesth Prog. 2012 Winter;59(4):154-158.15. Axelrod D, Bell C, Feldman J, et al. Greening the Operating Room and Perioperative Arena: Environmental Sustainability for Anesthesia Practice. American Society for Anesthesiologists. Revised 2017. Anest Prog 2012; 59: 154-158. 16. Sherman J, Le C, Lamers V, Eckelman M. Life cycle greenhouse gas emissions of anesthetic drugs. Anesth Analg. 2012; 114: 1086-1090. 17. Langbein T, Sonntag H, Trapp D, et al. Volatile anaesthetics and the atmosphere: atmospheric lifetimes and atmospheric effects of halothane, enflurane, isoflurane, desflurane and sevoflurane. Br J Anaesth. 1999; 82: 66-73.ReferencesAlain Kalmar biographyDr. Kalmar is an MD graduate of Ghent University. He completed a degree in  biomedical engineering before training in anesthesiology at Ghent University  Hospital. He obtained a PhD in Medical Sciences at Groningen University, a PhD  in Engineering at Ghent University and an MBA at Vlerick Business School. He has  a particular interest in cerebral hemodynamics and medical device development, and in recent years he has been engaged in growing awareness of the atmospheric effects of volatile anesthetics. He is staff anesthetist and principal investigator at AZ Maria Middelares in Ghent, Belgium, and academic consultant at the faculty of Health, Ghent University.

The environmental footprint of anesthetic agents

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The environmental footprint of anesthetic agents

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