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Technical Case Study

by J. A. Devlin-Hegedusa,b, F. McGainc,d, R. D. Harrise,f and J. D. Shermang,h

Approach:

By reducing pollution from inhalational anesthetics, health systems can provide high-quality care at lower environmental and financial costs. An effective approach can include: 

  • Educating providers about the environmental impact of inhaled anesthetics 
  • Setting clear targets and measuring performance across the system 
  • Prioritizing high impact interventions to reduce the use of agents with disproportionately high climate effects (desflurane and nitrous oxide) and minimize wastage of inhalational anesthetics

1. Why take action?  

Anaesthesia is a carbon-intensive specialty, involving the routine use of inhalation agents that are potent greenhouse gases. These gases are exhausted directly to the atmosphere, contributing to global warming. Relevant inhalational anaesthetics include volatile halogenated organic compounds (sevoflurane, desflurane, isoflurane, halothane) and nitrous oxide. While the environmental impacts of these agents should be mitigated, those of desflurane and nitrous oxide are several times greater in clinically relevant quantities, making them an even greater priority for intervention1. The global warming potential of desflurane is over 2500 times that of CO2 and approximately 40-50 times that of sevoflurane and isoflurane2. Nitrous oxide has a similar global warming effect to desflurane at clinically relevant doses, due to its very long atmospheric lifetime1.  

Volatile anaesthetic agents have been estimated to be responsible for 0.01–0.10%2,3 of total global carbon dioxide equivalent (CO2e) emissions contributing to global warming. Based on atmospheric sampling of volatile anaesthetics, their accumulation is increasing (particularly desflurane)4. Whilst these are a seemingly small contribution to total global emissions, inhalational anaesthetics account for 5% of acute hospital CO2e emissions and 50% of peri-operative department emissions (in high-income countries)1,5,6.  

Within anesthesia, there have been calls for action on climate change mitigation at work and beyond for more than a decade, and to move from sustainability research to action. Health systems and facilities around the world are already implementing actions to reduce pollution from inhalational anesthetics. Use of inhalational anesthetics is directly within the control of anesthesia providers and options exist to reduce their impact without compromising patient safety or quality of care. Anesthesia pollution reduction is an important opportunity for greenhouse gas mitigation and professional sustainability leadership for anesthesia providers and health systems. 

 

KEY MESSAGES:

  • Inhalational anesthetic agents are potent greenhouse gases, which are exhausted directly into the atmosphere and contribute to global warming. 
  • There are numerous, meaningful actions that can reduce pollution from inhalational anesthetics. These actions:  
    • Are practical to implement  
    • Uphold high-quality patient care  
    • Often lead to cost savings
Source: Shutterstock

2. How to get started 

Numerous health services around the world have undertaken effective interventions to reduce emissions associated with inhalational anesthetics, with both environmental and financial benefits. The following is a list of practical steps that can be taken, based on existing interventions from around the world. 

2.1. Key learning: Education around the environmental impact of inhaled anesthetics 

To begin, it is important to educate practitioners and anesthesia departments about the environmental impact of anaesthetic practice. This should include institutional- and provider-level inhalation anaesthetic CO2e performance and strategies to reduce emissions, which include7: 

  • The avoidance of high impact agents (desflurane and nitrous oxide) 
  • Reduction of usage with low-flow anesthesia and decommissioning of centrally piped nitrous oxide systems (and substitution with portable canisters) 
  • Consideration of alternatives with a lower environmental impact (e.g. total intravenous anesthesia) 

Several examples from around the world show how this can be done. The University of Wisconsin labelled vaporizers with environmental impact information and the use of desflurane was reduced by 55% in 2015. The intervention resulted in an average emissions reduction per anesthetic case from 163 kgCO2e to 58 kgCO2e8 and monthly cost savings of £16,340 (€22,537, $USD 25,000; using 2015 figures9). Desflurane was removed subsequently from the formulary in 2020. 

In Australia/New Zealand, anaesthetic trainees formed TRA2SH (Trainee-led Research and Audit in Anaesthesia for Sustainability in Healthcare), a network aiming to encourage research and quality improvement initiatives around environmental sustainability. It promotes an online pledge encouraging anaesthetic departments to immediately reduce their use of desflurane and remove it from their hospital formulary by 2025. Several institutions removed desflurane, whilst many others have pledged to do so by 202510. 

In the United Kingdom, the Nitrous Oxide Project11 was launched in January 2021, following the successful reduction in nitrous oxide use at the NHS Lothian outlined above. This project provided resources to assist others to audit and reduce nitrous oxide use in their institutions. By the end of March 2021, 16 hospitals reported an annual system loss of 13,770,000 l, equivalent to 95% of total procured nitrous oxide. This is equivalent to 7219 tons CO2e, comparable to 7600 flights from Paris to New York12. 

 

2.2. Key learning: Target setting and performance measurement 

It is important to set target emissions reductions and timelines (e.g. 50% reduction by 2023). Emissions performance can be tracked over time through simple audits of quantities of purchased volatile anaesthetic and nitrous oxide within a facility. For volatile anaesthetics, providers may request procurement data from their pharmacy on quantities purchased on a semi-annual basis. Procurement data on quantities of nitrous oxide canisters purchased can be obtained through the medical gas department on a semi-annual basis. Where electronic health record data are available, average FGF, inhaled drug types, concentrations and numbers of hours of anaesthesia delivered can be obtained to calculate emissions for each provider7.  

 

2.3. Key learning: Prioritizing high-impact strategies to reduce emissions 

The following strategies have been shown to have the greatest impact on reducing anesthesia pollution at provider and health system level.  

Eliminating desflurane:  

  • The Yale New Haven Health System (CT, USA) eliminated desflurane from their formulary in 2013 in favour of sevoflurane13. The resultant decrease in GHG emissions was 1600 tonnes CO2e (the equivalent of 360 passenger vehicles over 1 year, based on calculations using 2012 fuel efficiency figures14) and annual cost savings were approximately £769,230 (€909,090, $USD 1,200,000; using 2013 figures15) across the health system. 
  • In Australia, Fiona Stanley Hospital (Perth, WA) removed desflurane in 2020 which reduced approximately 300 tonnes CO2e per year (personal communication, C Mitchell) and saved approximately £51,916 (€58,572, $USD 66,560; based on 2020 figures). At Western Health, a district health service with 960 beds in Melbourne, Australia, this same intervention reduced emissions by 140 tonnes CO2e per year and saved £17,308 (€19,527, $USD 22,190 based on 2020 figures).  

Reducing Fresh Gas Flow (FGF) rate during use of inhalational anaesthetics:  

  • The University of California (San Francisco, CA, USA) implemented an electronic clinical decision support tool, aimed at nudging providers to reduce FGFs in real time. This electronic health record tool alerts providers if FGF exceeds 0.7 l.min-1 for desflurane and 1 l.min-1 for sevoflurane during maintenance anaesthesia. In 2018, researchers demonstrated reductions in (already low) mean FGF by 0.6 l.min-1 for sevoflurane and 0.2 l.min-1 for desflurane (personal communication, S Gandhi). 

Reduce usage of nitrous oxide through decommission of centrally piped nitrous oxide 

  • In 2019, Providence St. Vincent Hospital (Portland, OR, USA) decommissioned central piped nitrous oxide and substituted with portable cylinders. This resulted in saving 958 tonnes CO2e in one year, equivalent to 2,407,640 fewer car miles driven and £9747 (€11,501, $USD 12,000) in procurement costs (personal communication, B Chesebro).  
  • In 2020, NHS Lothian (Scotland) demonstrated system losses from three centrally piped nitrous oxide systems across two hospital sites of approximately 790,000 and 685,000 litres, respectively. Mitigation activities, including fully decommissioning centrally piped nitrous oxide, eliminated the equivalent of 806 tonnes CO2e per annum.  

 

KEY MESSAGE:

  • High impact interventions target agents with disproportionately high climate effects (desflurane and nitrous oxide) and minimize wastage of inhalational anesthetics. 

 

3. Tracking progress  

There are several free calculators available to help providers estimate the environmental impact and costs associated with anaesthesia. This can help translate the above information into meaningful metrics for providers that help characterize their impact, such as CO2e per minimum alveolar concentration (MAC)-hour and equivalent distance driven per MAC-hour. This information is important to track institutional performance, inform policy, teach and encourage personal practice improvement. 

Source: Shutterstock

4. In practice  

There is an urgent need for coordinated action to minimise the environmental harms associated with healthcare delivery, and anaesthesia providers are well placed to make a meaningful contribution and demonstrate leadership around this problem. Removing desflurane from formularies, decommissioning central nitrous oxide piping systems, avoiding nitrous oxide use and minimising fresh gas flows are powerful and achievable actions to mitigate pollution from inhalational anaesthetics. 

 

5. Key resources 

More information: 
For more information, please contact Jessica Devlin-Hegedus at jessica.hegedus@health.nsw.gov.au

 

6. Author affiliations and references

a. Consultant, Department of Anaesthesia, Wollongong Hospital, Wollongong, NSW, Australia 
b. Clinical Senior Lecturer, Graduate School of Medicine, University of Wollongong, NSW, Australia 
c. Physician, Departments of Anaesthesia and Intensive Care, Western Health, Footscray, VIC, Australia 
d. Associate Professor, Department of Critical Care, University of Melbourne, VIC, Australia 
e. Lecturer, School of Medicine, University of Sydney, NSW, Australia 
f. Senior Specialist, Department of Intensive Care, Royal North Shore Hospital, Sydney, NSW, Australia 
g. Associate Professor, Department of Anesthesiology, Yale School of Medicine, New Haven, CT, USA 
h. Associate Professor, Department of Environmental Health Sciences, Yale School of Public Health, CT, USA 

 

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  8. Zuegge KL, Bunsen SK, Volz LM, et al. Provider education and vaporizer labeling lead to reduced anesthetic agent purchasing with cost savings and reduced greenhouse gas emissions. Anesthesia and Analgesia 2019; 128: e97–9
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  15. ExchangeRates.org.uk. British Pound to US Dollar Spot Exchange Rates for 2013. www.exchangerates.org.uk/GBP-USD-spot-exchange-rates-history-2013.html (accessed 04/05/2022) 
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