Abandoning inhalational anaesthesia

The 2018 Intergovernmental Panel on Climate Change (IPCC) Special Report Global Warming of 1.5°C (SR15) makes sobering reading 1. At the current rate, global warming is likely to reach 1.5°C above pre-industrial levels between 2030 and 2052, and this is likely to result in far-reaching effects, including: climate change; sea level rise; loss of biodiversity; global health problems; food and water shortage; mass migration; and geopolitical insecurity. Adaptation to these challenges remains possible below a rise of 1.5°C, but would become increasingly difficult towards 2°C and beyond, as ‘tipping points’ are exceeded. Limiting global warming to 1.5°C will require global net emissions of carbon dioxide to fall by approximately 45% from 2010 levels by 2030, reaching ‘net zero’ around 2050 1. These targets are much more stringent than those agreed by the 1998 Kyoto Protocol 2, exceed the scope of the 2015 Paris Agreement 3 and will require ‘rapid and far reaching’ co-operative global socio-economic changes, including: shifts to renewable energy; changes to food systems; transport electrification; urban restructuring; and carbon capture. Independent consensus supports the immediacy of the changes needed 4. Inhalational anaesthetic agents are fluorocarbons that contribute to man-made climate change primarily through ‘radiative forcing’ (i.e. acting like greenhouse gases), but also through the carbon cost of their life cycle (manufacture, storage, transport, use and recovery). Their global warming potentials can be compared with that of carbon dioxide over a given time period (usually 20 years or 100 years). Desflurane has the highest global warming potential (one 240-ml bottle of vaporised desflurane being equivalent to the global warming effect of 1296 kg CO2 over 20 years), much higher than that of isoflurane and sevoflurane (521 kg and 132 kg CO2 equivalents (CO2e).250ml−1 bottle, respectively) 5-7. Currently, the global market for inhalational anaesthetic agents is ~12.5 million bottles (worth US$1.12 billion), a figure projected to rise to ~14.9 million bottles by 2025 (worth $1.34 billion) 8. Sevoflurane is the market leader (sevoflurane 70%, desflurane 20%, isoflurane 10%). From these figures, and assuming negligible recovery or metabolism, the estimated annual contribution of inhalational anaesthetic agents represents ~ 0.01% of global CO2 production (0.005/37.1 Gt CO2e) 9. Although a relatively small proportion, this is equivalent to flying an average commercial airliner ~418 times around the world. The NHS Sustainable Development Unit has estimated that anaesthetic gases (including nitrous oxide) contribute ~5% of the carbon footprint of UK hospitals (~0.56/10.4 million tons CO2e; ~0.08 mt (~0.8%) inhalational anaesthetic agents only) 10. An anaesthetist using low-flow (< 0.5 l.min−1) 6% desflurane in 50/50 air/O2 after intravenous induction in theatres without scavenging, uses ~60 ml desflurane during a 7-h operating list 11. If the gases are vented to the atmosphere (as is invariably the case), this is equivalent to ~ 325 kg CO2 (GWP20). Assuming three lists.week−1, 45 weeks.year−1, over a 40-year career, that anaesthetist would have been responsible for releasing 1755 tons CO2e; this is equivalent to ~880 return passenger flights between London Heathrow and JFK airports, ~ 22.year−1 or one trans-Atlantic flight for every week of work. The Association of Anaesthetists has done much to raise professional awareness about the environmental impacts of using inhalational anaesthetic agents and how to mitigate these [https://anaesthetists.org/Home/Resources-publications/Environment], and recently supported the NHS ‘Clean Air’ day [https://anaesthetists.org/Home/Resources-publications/Environment/Clean-Air-Day-2019]. Similarly, the Royal College of Anaesthetists has recently committed to minimising the environmental effects of anaesthesia, but without specifically addressing the impact of inhalational anaesthetic agents 12. Other authors have called for enhanced awareness of the environmental harms of inhalational agents and reductions in their use through low-flow anaesthesia 13 and the capture and reprocessing of exhaled vapours 14. However, even if these technologies were universally available and affordable, atmospheric escape of inhalational agents would continue to occur. Instead, given the urgency required to avoid the imminent climate catastrophe identified by the IPCC, we argue that it is ‘too late to mitigate’: the profession of anaesthesia must consider specifically abandoning the use of inhalational anaesthetic agents by 2030. Given their environmental impact, it is perhaps surprising that the use of inhalational anaesthetic agents has not been addressed by either international climate agreements or national carbon reduction strategies, to date. Neither the Montreal Protocol and Kigali Amendment (dealing with ozone depletion) nor the Kyoto Protocol and Paris Agreement mention inhalational anaesthetic agents. Likewise, they are not referred to in the Climate Change Act 2008, its healthcare application in the NHS Carbon Reduction Strategy 2009, or in the more recent UK Carbon Plan 2017, even though the UK Government has recently committed to net zero carbon emissions by 2050. This may be oversight on the part of the authorities involved, but it may also represent a form of healthcare exceptionalism, in effect ignoring the environmental harm caused by inhalational anaesthetic agents because they are considered indispensable for healthcare. But are they? Locoregional anaesthesia (LRA) and total intravenous anaesthesia (TIVA) can be equally effective as, and in some cases superior to, inhalational anaesthesia 15. We accept that these options are not without their own environmental costs, but even accounting for the increased production of (often plastic) waste involved in these modalities, their carbon impact is many times less than that of the inhalational alternative. Furthermore, we suggest that there is no absolute indication for inhalational anaesthesia use that could not be substituted using LRA/TIVA, including: the management of complex airways; unfasted patients; those with poor vascular access; and anaesthesia for bariatric and paediatric surgery. Barriers to the use of LRA/TIVA in these contexts appear to relate more to operator confidence than to evidence. Although we fully accept that additional research would be valuable, it appears that better training should be the primary focus in aiding their adoption 16. Perhaps the main reason that the profession has been sluggish in committing to using alternatives to inhalational anaesthesia is cultural. Inhalational anaesthesia remains the default method of providing general anaesthesia, globally. Delivered by ‘gas(wo)men’, its effectiveness has been confirmed through many patient-years of experience. From the outset of their specialist education, anaesthetists are taught that inhalational maintenance is the ‘standard’ option for providing general anaesthesia. In contrast, TIVA does not appear as a training objective until page 66 of the Royal College of Anaesthetist's Intermediate Training Curriculum, and is framed as an ‘alternative’ to inhalational anaesthesia, against which its comparative risks and benefits should be assessed. Why shouldn't the converse apply in future iterations of the document? Bowker and Star have pointed out that superior marketing and the favour of a community of gatekeepers may maintain the use of established standards ahead of those which may be technological improvements, noting “there is no natural law that the best standard shall win” 17. We suggest that the continued pre-eminence of inhalational anaesthesia within the orthodoxy of our profession occurs not due to any clinical superiority but due to a clinical tradition and an educational model that makes such acceptance almost inevitable. Critics of our position may point out that anaesthetists have a duty to provide safe and effective anaesthesia to the patient in front of them, and that for many clinicians this means using an inhalational technique. However, we suggest that we also have a duty of care to a person whose health is, or will become, affected by climate change, which will include people in the UK if global warming continues at its current rate 18. We recognise that change is difficult. There are challenges for those who choose to adopt TIVA as their primary method of administering general anaesthesia, for example, although many sources of information and training aids exist 16, 19. Professionally, however, we have always been able to accommodate similar considerations (e.g. when propofol was introduced replacing thiopentone, and when halothane/enflurane use was discontinued). In addition, we need to recognise that patients may increasingly express a shared decision-making interest in the carbon footprint of their healthcare. The National Institute for Health and Care Excellence (NICE), for example, has recently published a decision aid to help patients and their doctors choose an appropriate metered-dose inhaler for asthma management based not only on clinical factors but also on the carbon footprint of each dose of medication 20. If patients are questioning the carbon impact of their inhalers, we do not think that it will not be long before patients ask similar questions about their anaesthetic. How might cultural obstacles to change be overcome? Probably the most important and effective option is for individual anaesthetists to take personal responsibility and commit to abandoning inhalational anaesthetic agent administration, as well as advocating for changes within their department and nationally. Professionally, bodies such as the Association of Anaesthetists, Royal College of Anaesthetists, American Society of Anesthesiologists and European Society of Anaesthesiology need to: publicly and explicitly support the rapid phasing out of inhalational anaesthetic agents through improved education and endorsement of alternative methods of anaesthesia; re-allocate research funding away from studies involving fluorocarbon inhalational agents; and reduce sponsorship income from inhalational anaesthetic agent manufacturers, but work (perhaps preferentially) with these companies to find environmentally neutral alternatives through research). Nationally, and internationally, governments, institutions and non-governmental organisations need to: formally recognise the contribution to global warming made by inhalational anaesthetic agents; and commit to phasing out their use within carbon reduction strategies, as well as supporting research by the manufacturers into carbon-neutral alternatives. In order that anaesthetists and patients can make informed choices about anaesthetic technique, manufacturers should be compelled to make accurate data available regarding the life-cycle carbon impact of volatile agents and their alternatives, as well as the volume and destination of annual inhalational anaesthetic agent sales. It has been postulated that it takes ~17 years to change practice in healthcare systems 21, and given that the IPCC has forecast that global warming will exceed the 1.5°C critical threshold between 11 and 33 years time unless its recommendations are implemented, it seems incumbent on our profession to reduce its carbon footprint as soon as possible. Foremost among the ‘rapid and far-reaching’ options available to us to achieve this is to abandon inhalational anaesthesia agent use. If they haven't done so already, we strongly urge colleagues to play their part in setting a new standard of care which benefits not only the patient in front of them but also the health of future generations, by changing their practice accordingly. CS is a co-opted member of the Association of Anaesthetist's Environment and Sustainability Committee. No external funding or competing interests declared.

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