Dr Rebecca Marshall

Towards a More Sustainable Anaesthesia Practice

A Review of ‘Environmental Sustainability in Anaesthesia and Critical Care.’ BJA, 2020.

The climate crisis is one of the greatest threats facing humanity today, with widespread global health implications. The health-care sector itself is responsible for approximately 4.6% of global greenhouse gas emissions annually, or close to 2 gigatons of carbon dioxide equivalents (CO2e); emissions on par with a country almost the size of Russia.(1)

Moving towards a more sustainable practice in anaesthesiology and critical care medicine is increasingly being recognised as a key priority as our reliance on single-use medical equipment, plastics and pharmaceuticals places a substantial burden on the environment.(2) To this end the CAI have recently published an advocacy statement on environmentally sustainable practice and have set up a Sustainability Committee with the objective of minimising the environmental footprint of our speciality in Ireland. A paper recently published in the BJA by McGain et. al; ‘Environmental sustainability in anaesthesia and critical care’, offers a comprehensive review of the existing research in this area, and addresses why it matters, what is known, and ideas for future work.(3) Anaesthetic gases, particularly N2O are responsible for an estimated 5% of the total carbon footprint of an acute NHS organisation. The global warming potential (GWP) of a gas depends on its radiative efficiency and atmospheric lifetime, with N2O having a GWP 265 times that of CO2. In addition, N2O is responsible for most ongoing ozone depletion. Volatile anaesthetics are responsible for roughly 0.1% of global warming, or 1 million US cars on the road yearly. The worst culprit is desflurane with an atmospheric lifetime of 14 years (vs. sevoflurane 1 year). One could easily drive the equivalent of 1000km/day using low flow (1L/min) desflurane and N2O, whereas one MAC-hour of sevoflurane (2.2% at 1L/min FGF) in air is analogous to 6.5km driven. In addition to minimum flow anaesthesia (<1L/min FGF) as a reliable way to mitigate atmospheric waste anaesthetic gases (WAGs), the authors discuss promising WAG capture and destruction technologies e.g. rooftop installations with a heated catalyst to destroy N2O (routinely used in Sweden); a one-way valve scavenging interface that aims to reduce energy costs and requirements by decreasing air entrainment. Life cycle assessments (LCAs) which analyse the ‘cradle to grave’ environmental ‘footprint’ associated with resource extraction, manufacturing and disposal of products or processes, have progressed the scientific foundation for environmental sustainability in anaesthesia and critical care over the past decade. LCAs comparing reusable with single-use anaesthesia equipment e.g. drug trays, LMAs, laryngoscope blades, theatre attire etc., have shown that in general, reusable items have both lower financial and carbon footprints (dependent on the energy source of the health system; fossil fuels vs renewables, and water usage). A quoted study looking at pharmaceuticals by Sherman et. al showed that TIVA is preferable to inhaled anaesthetics, with the GWPs of inhaled agents four times greater than a MAC equivalent quantity of propofol, even accounting for plastic syringes, tubing and drug pump electricity.(4) It is important to note that the correct disposal of propofol is vital, as incorrect dumping can contribute to water contamination with deleterious effects on aquatic life. A 2018 LCA by Pollard et al. examining the carbon footprint of treating ICU patients with septic shock reported CO2e emissions between 88kg – 178kg CO2e patient-1 day-1 (Australia and USA respectively), dominated by energy use for heating, ventilation and air conditioning (HVAC), with only minor variations in individual patient carbon footprints according to the intensity of care.(5) This would suggest that moving to more renewable sources of energy would have the greatest impact on mitigating the ICU’s carbon footprint. The article cites that ‘operating suites produce a quarter of all hospital waste (up to 25% of that from anaesthesia)’, and that approximately 25% of operating room and 15% of critical care waste can be recycled, with 1 ton of recycled mixed plastics equivalent to saving enough energy to power an average US household for six months! Reprocessing single-use equipment for reuse e.g. surgical staplers, BP cuffs etc. is another way to save money and reduce emissions, and one that is already occurring in many countries around the world. So how should all of this inform our daily practice? First and foremost we should avoid desflurane and N2O, which the authors suggest would have the greatest impact in reducing the carbon footprint of anaesthesia. We should practice low flow anaesthesia (~1L min-1 FGF), and embrace TIVA and regional techniques where clinically appropriate, approaches already encouraged by the ASA Task Force on the Environment. Some exciting work is currently ongoing by the Sustainability Committee to quantify our national annual usage of inhalational agents. Other simple things we can do include switching to washable theatre hats, drawing up the minimum amount of drug syringes at the beginning of the day, ensuring correct waste disposal (only sharps in the sharps bin!), and taking responsibility for turning off anaesthetic machines, scavenging and suctioning at days end. We should embrace the opportunity to become leaders in championing a more environmentally sustainable practice lobbying hospital management for waste recycling and getting involved in product evaluation committees to ensure procurement of more environmentally friendly products. Finally, as a collective group we can push the ‘powers that be’ for a switch to more renewable energy sources for our health systems.


1. Watts N, Amann M, Arnell N, Ayeb-Karlsson S, Beagley J, Belesova K, et al. The 2020 report of The Lancet Countdown on health and climate change: responding to converging crises. The Lancet. 2021;397(10269):129-70. 2. Shelton CL, McBain SC, Mortimer F, White SM. A new role for anaesthetists in environmentally-sustainable healthcare. Anaesthesia. 2019;74(9):1091-4. 3. McGain F, Muret J, Lawson C, Sherman JD. Environmental sustainability in anaesthesia and critical care. British Journal of Anaesthesia. 2020;125(5):680-92. 4. Sherman J, Le C, Lamers V, Eckelman M. Life cycle greenhouse gas emissions of anesthetic drugs. Anesth Analg. 2012;114(5):1086-90. 5. Pollard AS, Paddle JJ, Taylor TJ, Tillyard A. The carbon footprint of acute care: how energy intensive is critical care? Public Health. 2014;128(9):771-6.