As we witness the closing of the 27th Conference of the Parties to the United Nations Framework Convention on Climate Change, A. K. A. COP27, we recall UN Secretary-General Antonio Guterres speech urging the world not to relent “in the fight for climate justice and climate ambition”. Specifically, he re-emphasized the goal set out within the Paris Agreement in limiting global warming to well below 2, preferably to 1.5 degrees, describing it as a “red line” that we must not cross (1).
It is all too easy to become overwhelmed by global challenges such as climate change. Change however, begins from individuals, to organisations and the society. Drawing much closer to home, what can we do as current and future anaesthetists in contributing towards the grand plan set out in the Paris Agreement?
The environmental impact of anaesthetic gases
Anaesthetic gases, notably nitrous oxide (N2O) and halogenated hydrocarbons, represent 5% of the carbon footprint for all acute NHS organisations. N2O contributes to more than three-quarters of the carbon footprint (2). It is a popular agent for its versatility, relative efficacy and safety. It is utilized in obstetric anaesthesia, often as an alternative to neuraxial analgesia. It is also a popular agent as a carrier gas for other volatile anaesthetic agents to decrease the effect of the latter on cardiac depression and systematic vascular resistance. Outside of the operating theatre, N2O is used extensively for minor procedures such as fracture reduction(3).
N2O is however one of the most environmentally damaging gases in the atmosphere. It has a global warming potential that is 298 times that of CO2, and is recognized to be the dominant ozone-depleting substance emitted by human activity (4). We must therefore think carefully about standardizing and limiting its usage and opt for alternative agents where possible.
Of the commonly used inhalational anaesthetic agents, desflurane has the greatest environmental impact, with a global warming potential 2540 times of CO2(5) This means that using desflurane with a modern anaesthetic machine for 1 hour can produce the same amount of CO2 as a 304km trip in a modern car (6)!
Table of GWP of commonly used anaesthetic gases
Anaesthetic agents | Global warming potential |
Desflurane | 2540 |
Sevoflurane | 130 |
Isoflurane | 510 |
Nitrous oxide | 265 |
What anaesthetists can do in our daily clinical practice
How can anaesthetists make a difference in the environmental footprint of their daily practice?
The choice of anaesthesia is determined by patient, surgical and anaesthetic factors, as well as individual preferences of the anaesthetists. Anaesthetists have the responsible to not only care for the patients in front of them, but also to safeguard the health and wellbeing of the future generations. Nevertheless, patient safety must not be compromised by the practices of sustainable anaesthesia.
When thinking about the anaesthetic agent, can we opt for alternative techniques that can reduce the environmental impact, such as regional anaesthesia and total intravenous anaesthesia (TIVA)? When this is not possible, can we rationalize the use of inhalational agent with the least amount of carbon footprint, and minimize the quantity of agent usage by monitoring the depth of anaesthesia and flow rate? Inhalation anaesthesia offer advantages including the ease of usage, improved cerebral and cardiac protection, while TIVA has a favourable profile for postoperative recovery, and is the preferred agent for cancer resection surgeries (7).
Beyond anaesthetic gases
Many other anaesthetics practices contribute towards medicines waste. As specialties that are frequently called to initiate emergency pharmacological treatments under time-limited conditions, it is standard practice for anaesthetists to prepare the main anaesthesia and emergency drugs in advance, in order to mitigate the risk of medication error under stressful situations. However, this can lead to significant medication wastage. An estimated 20-50% of drugs drawn up are unused and discarded (8). Potential strategies include the use of prefilled syringes, especially for those drugs that are of high-acuity but low-usage, such as atropine and ephedrine. The use of prefilled syringes in prediluted forms can also help to reduce the risk of medication errors, especially when dealing with variations in drug concentrations.
What can you do today?
Royal College of Anaesthetists have a dedicated a range of resources on environment and sustainability (2). The e-learning module will be highly informative for budding anaesthetists and anaesthetists in-training. There are also a range of blog articles and a fun anaesthetic impact calculator for those of you that are interested. In addition, look out for movements such as GASP (Greener Anaesthesia & Sustainability Project), a nationwide, non-profit multidisciplinary movement led by the anaesthetics community, that you can potentially join to play a part! See https://www.gaspanaesthesia.com/ for more information.
At the early stages of our careers, it is important to develop an awareness of the greater issues facing our specialty, so that as we take on the responsibility in representing the future of anaesthesia, we can be better prepared for the challenges that we will be facing.
Change starts with us.
Author: -References
1. United Nations. COP27: Delivering for people and the planet | United Nations [Internet]. [cited 2022 Dec 2]. Available from: https://www.un.org/en/climatechange/cop27
2. The Royal College of Anaesthetists. Environment and sustainability [Internet]. [cited 2022 Dec 2]. Available from: https://rcoa.ac.uk/about-us/strategy-vision/environment-sustainability
3. Lew V, McKay E, Maze M. Past, present, and future of nitrous oxide. Br Med Bull [Internet]. 2018 Mar 1 [cited 2022 Dec 2];125(1):103–19. Available from: https://academic.oup.com/bmb/article/125/1/103/4925059
4. Muret J, Fernandes TD, Gerlach H, Imberger G, Jörnvall H, Lawson C, et al. Environmental impacts of nitrous oxide: no laughing matter! Comment on Br J Anaesth 2019; 122: 587–604. Br J Anaesth. 2019 Oct 1;123(4):e481–2.
5. McGain F, Muret J, Lawson C, Sherman JD. Environmental sustainability in anaesthesia and critical care. BJA: British Journal of Anaesthesia [Internet]. 2020 Nov 1 [cited 2022 Dec 2];125(5):680. Available from: /pmc/articles/PMC7421303/
6. Gordon D. Sustainability in the Operating Room: Reducing Our Impact on the Planet. Anesthesiol Clin. 2020 Sep 1;38(3):679–92.
7. Lim A, Braat S, Hiller J, Riedel B. Inhalational versus Propofol-Based Total Intravenous Anaesthesia: Practice Patterns and Perspectives among Australasian Anaesthetists. https://doi.org/101177/0310057X1804600509 [Internet]. 2018 Sep 1 [cited 2022 Dec 2];46(5):480–7. Available from: https://journals.sagepub.com/doi/10.1177/0310057X1804600509
8.Rinehardt EK, Sivarajan M. Costs and wastes in anesthesia care. Curr Opin Anaesthesiol [Internet]. 2012 Apr [cited 2022 Dec 2];25(2):221–5. Available from: https://journals.lww.com/co-anesthesiology/Fulltext/2012/04000/Costs_and_wastes_in_anesthesia_care.17.aspx
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