Portal de Periódicos da CAPES

Desflurane decommissioning: more than meets the eye

2024; Wiley; Volume: 79; Issue: 3 Linguagem: Inglês

10.1111/anae.16219

1365-2044

Ramani Moonesinghe,

Cardiac Arrest and Resuscitation

In April 2024, NHS England will finalise the decommissioning of the volatile anaesthetic agent desflurane. The stance we hope will be adopted in England follows the example set by NHS Scotland in 2023. For the benefit of the 'Gen Z' folk who might one day read this, when desflurane was introduced into the NHS it had a clear 'unique selling point': rapid onset and offset. It also had some disadvantages, including tachycardia and airway irritation. But for many anaesthetists (including me) it had a useful place in our armoury. Back then, the alternatives were isoflurane (slow onset and offset) and sevoflurane (not as quick as desflurane and very expensive – my clinical director locked it away in all but the paediatric areas). There was a handful of 'early adopters' using fancy algorithms on syringe pumps to provide total intravenous anaesthesia (TIVA), but as we never seemed to have enough pumps, I had an excuse not to engage in debate over the Marsh vs. Schnider models. But times change, and so do our interests and habits. Sevoflurane is no more expensive than other volatile agents [1] and TIVA is used widely [2]. Over time, anaesthetists have moved away from using desflurane. In part, this has been down to clinical preference, but for many, the climate change argument has been the deal-breaker [3, 4]. So, what is the argument? I think there are points regarding the climate impact of desflurane which are uncontentious. The first is that it is a greenhouse gas. The UK and all other signatories of the Paris Agreement currently report greenhouse gas emissions to the United Nations Framework Convention on Climate Change. The internationally accepted unit used for reporting greenhouse gas emissions is their global warming potential over a 100-year period (GWP100). The UK has committed to reduce all greenhouse gas emissions to net zero (that is, having an equal balance between the amount of greenhouse gas produced and the amount removed from the atmosphere) by 2050, with a reduction of at least 68% by 2030. These legally binding targets cover all greenhouse gases, including desflurane, and are measured using GWP100. However, over the last year or so, significant coverage has been given to the perspective that GWP100 is the wrong metric to use when considering the climate impacts of short-lived greenhouse gases, including volatile anaesthetic agents [5, 6]. This has implications for estimating the adverse impacts that different types of greenhouse gas have on the environment. From there, the argument has been made that the impact of desflurane on the environment is so trivial that there is no need for clinicians to change their practice and that any national policy should be reversed because the only thing which should matter is providing the right anaesthetic to the patient. I am not a climate scientist. For an anaesthetist, I am embarrassingly bad at physics. I do not question the climate scientists. But they do question each other [7-9] just like we clinician-scientists have healthy debates about which (and how much) fluid, which anaesthetic, which block, and pretty much everything else. So, I guess it is not surprising that there are different perspectives on the environmental impact of desflurane, and that the NHS England decision to decommission it has led to a public debate [10, 11]. For whatever reason, the use of desflurane in the NHS has fallen dramatically; current usage data are available from the NHS Business Services Authority (NHSBSA) Open Data Portal (Fig. 1) [12]. We do not have perfect metrics for it, but the best estimate we have is that it accounts for around 0.5% of total volatile anaesthetic agent use by volume. Given its low potency compared with sevoflurane and the growing use of TIVA, this means that the amount of actual anaesthesia administered using desflurane is minimal. Although there have been mandates to reduce desflurane use in the NHS standard contract for some years [13, 14], clinicians have gone much further than the contractually binding targets. Many hospitals have completely decommissioned it already [15, 16]. This has been clinically led. Many of you reading this will have been involved in these initiatives locally. The Royal College of Anaesthetists and the Association of Anaesthetists have been broadly supportive of this initiative for many years. So, when NHS England approached the professional bodies to support a decommissioning approach, this was done in the knowledge that there was likely to be broad community support, as well as support from the professional bodies. The decommissioning announcement was made in January 2023 [17], and since then there has been a lot of activity preparing for policy implementation. This included stakeholder engagement with other professional groups, including various anaesthesia specialist societies. Commissioned by NHS England, the National Institute for Health and Care Excellence (NICE) has undertaken an evidence review which, with the agreement of our professional partners, focused on neuroanaesthesia and anaesthesia for patients living with obesity (whether for bariatric or other surgery) as these were felt to be the clinical settings in which there might still be equipoise about the potential benefits of desflurane. Details of this process and the outcomes of the review will be published in due course. Without giving away any spoilers, we can refer to the existing published literature which compares clinical outcomes and other endpoints (such as time to tracheal extubation) between desflurane and other anaesthetic agents [18-23]. These studies do not show evidence of improvements in patient-centred outcomes with desflurane, but only that emergence or recovery time after general anaesthesia is quicker after a desflurane anaesthetic [22, 24]. So, the only issue is whether this matters from a clinical or service perspective. One can scrutinise the data in the most recent meta-analysis on this topic (which was industry funded), which reported the relative risk of prolonged time to tracheal extubation (defined by the authors as > 15 min) as its primary outcome. A minority of studies found there was a significant increase in the proportion of patients who had a prolonged time to tracheal extubation. However, perhaps interpreting the actual times to tracheal extubation and the absolute differences between agents might be more clinically important. Clearly, stakeholder consensus is important on this question. Two perspectives require consideration in relation to shorter times to tracheal extubation: the impact on the service and its efficiency; and the clinical impact on individual patients and their outcomes. These issues were discussed by a panel which had access to the NICE evidence review and included representation from the professional bodies and specialist societies which would have the greatest interest in the decommissioning of desflurane (Royal College of Anaesthetists, Association of Anaesthetists, Society for Obesity and Bariatric Anaesthesia, Neuro-Anaesthesia and Critical Care Society, and others). The full details and outcomes will again be published by NHS England in due course, but broadly speaking there was consensus on the clinical safety of decommissioning desflurane, the few exceptions which might need to be made and how that provision should be enabled. At this stage, it is necessary to reiterate that the policy is limited to decommissioning desflurane and does not promote TIVA over anaesthesia with other volatile agents. Multiple randomised trials are evaluating the clinical effectiveness of TIVA vs. volatile anaesthesia, and clinical practice should be driven by their results [25-27]. So far, so good. But what about the controversy? Is this all a waste of time because desflurane doesn't have any impact on the climate emergency? While I am not a climate scientist, I do consider myself to be a scientist, as I think all anaesthetists should consider themselves similarly. And national policy should be driven by the science. However, over and above climate physics, there are other types of science we need to consider. That includes behavioural science – not just of individuals (in this case, anaesthetists) but also of industry. Social scientists use theories to support develop, implement and evaluate new ways of doing things. One of my favourites is normalisation process theory [28]. Here, it is suggested that new approaches or interventions should follow four principles (Box 1). 1. Be coherent: is it easy to describe and convey? 2. Support cognitive participation: can people get behind this? Does it sound like a plausibly good idea? 3. Support collective action: what impact will it have on people? Will it make their lives easier, harder or make no difference? 4. Be capable of reflexive monitoring: can we get to the stage where instead of asking 'why are we doing this' we say 'why aren't we?' The best example I can think of for something we do in practice which ticks these boxes is the use of capnography in airway management. Work that one through in your head as an exercise. The key for me is that it feels impossible that we would get to the stage of administering induction agents without noticing if the capnography is missing. And we don't need to audit this or put it on the World Health Organization checklist. Following the publication of the RECOVERY trial [29], administering dexamethasone to hospitalised patients with COVID-19 was similar. It was a new thing which got rapidly adopted with excellent compliance [30]. Not the 17 years that it often takes for novel innovations to embed [31]. It feels to me that avoiding desflurane ticks all these boxes. There are clinical reasons not to use it (apart from the climate impact) and good alternatives, so it was a relatively easy win. I bet you that when it is used in most settings today, our younger colleagues will ask 'why are you using that?' to Baby Boomer or Generation X folk like me. I think this explains why desflurane is already almost a thing of the past. So, you may ask, why do we need a decommissioning policy? This is where industry comes in. Market forces drive industry behaviour. If they can't make a profit, they won't invest in the product. Profits will be driven by production costs and market demand. If the government makes the raw materials more expensive, then production costs will rise. If the alternative products are crowding the market, then demand will fall. Easy. Our collective action as an anaesthesia community has already sent a strong message to industry: don't be part of the problem (and, ideally, be part of the solution). Decommissioning further enhances this, as almost uniquely internationally, we can do this as a single system due to the NHS. This is really powerful. If evidence emerges that desflurane confers clinical benefit, then of course this decision can be reconsidered. This is no different to evidence-based medicine more generally; guidelines and policies change according to new data. Will this policy make a big difference to climate change? Even if you fully accept the assertion that volatile anaesthetic agents have a much smaller impact than previously thought (and it is important to recognise that there remains genuine discourse about this), it is unarguable that desflurane causes more radiative forcing than isoflurane or sevoflurane [5]. So, even if the environmental benefit of avoiding desflurane use is small, if patients are not harmed, then why wouldn't we do it? Small changes can cumulatively make a big difference [32]. It would be great to stop talking about desflurane and move on. Much more energy needs to be spent on addressing bigger healthcare-related sustainability challenges. In our world, nitrous oxide is a significantly greater problem than desflurane and there is a growing clinically led consensus that we don't need it for general anaesthesia in most instances. The New Hospital Programme will not include nitrous oxide pipework in operating theatres. In all hospitals, we need to move to a position where we decommission nitrous oxide manifolds, and instead have a few cylinders in the operating department for those occasional cases where we might still need it. This will not only reduce emissions through supporting behaviour change but also by reducing the huge leaks we know affect many manifolds [33, 34]. Entonox remains a challenge – we do not want to get rid of something which has clinical benefit without a suitable alternative. Technological solutions to this problem are being developed or have been implemented to some extent. These need robust evaluation and, if effective, spread and adoption [35]. The biggest sustainability challenges for the NHS are the same things we consider in our domestic lives. As well as 'heat and fleet' and supply chain considerations, a huge amount of work is ongoing on the 'waste hierarchy' (refuse, reduce, re-use and recycle) involving the Department of Health and Social Care, the NHS in all the devolved nations, clinicians and industry. There are already fantastic initiatives in our specialities related to these principles, such as the 'Gloves Off' campaign, which, in line with existing infection prevention and control recommendations, promotes reserving the use of examination gloves for instances when exposure to bodily fluids is likely. The NHS and the National Institute for Health and Care Research (NIHR) are both investing heavily in research and development to promote sustainability in healthcare. We need to help clinicians by developing more interventions based on theories such as normalisation process theory; supporting us to do the right thing for patients today, and the whole population tomorrow. Looking forward, it would be great to get to a position where when we consider which 'thing' to use, or which pathway to follow, we don't just consider patient benefit and cost, but we also actively consider the environmental impact. If we don't do this, then healthcare may not be able to keep up with the adverse impacts that climate change will have on individuals and society. I'd love to see this happen before I retire. So, in summary, let's stop talking about desflurane. It really is old news. The author thanks S. Ouhannon and Dr C. Shelton for their constructive critique. SM is the National Clinical Director for Perioperative and Critical Care at NHS England. In that role, she chairs the Anaesthesia, Peri-Operative Medicine and Pain Medicines Sustainability Working Group at NHS England and has clinically led the policy to decommission desflurane. She is co-developing Envirolieve, a novel medical device to reduce nitrous oxide emissions related to Entonox use in healthcare; the company Elegant Design and Solutions Ltd, of which she is a co-director, has received funding from the Small Business Research and Innovation (SBRI) fund for Envirolieve development. She is a co-investigator on the VITAL trial which is comparing the clinical effectiveness of volatile and total intravenous anaesthesia. She is supported by the National Institute for Health Research, through the University College London Hospitals Biomedical Research Centre, where she is a Theme Lead, and the Central London Patient Safety Research Collaboration, of which she is Director. This editorial represents personal opinion and the views expressed do not reflect those of the Department of Health and Social Care or NHS England.