The carbon footprint of general anaesthetics: A case study in the UK

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• The estimated carbon emissions of commonly used general anaesthetic vary across synthesising methods. • Sevoflurane has the potential to emit as little carbon as propofol in the presence of a vapour capture technology. • This is the first study to model the synthesis of the propofol liquid in a life-cycle framework while the current literature looked at the active pharmaceutical ingredient of propofol. • The 2018 UK anaesthetic usage data shows that the carbon footprint of sevoflurane is as larger as desflurane in most scenarios. The UK National Health Service (NHS) aims to achieve net zero carbon emissions by 2050. One measure for reaching this target outlined in the NHS long-term plan (2019) is to reduce the carbon footprint of inhalational anaesthetic gases (IAGs). We modelled the synthesis of commonly used IAGs - sevoflurane, isoflurane, and desflurane - in comparison to intravenous propofol and estimated the carbon footprint generated throughout their lifetime, from manufacturing of raw materials to emissions of IAGs vented from operating theatres. We find that the carbon footprint of IAGs varies significantly depending on the method of chemical synthesis. Our results indicate that the carbon footprint of IAGs is minimised when using oxygen/air mix as the carrier gas at the lowest flow rate while applying a vapour capture technology (VCT). In this scenario, the carbon footprint of sevoflurane per minimum alveolar concentration hour is similar to that of propofol, which is a significant finding given that previous studies have favoured propofol as a means of carbon footprint reduction and only the active pharmaceutical ingredient of propofol was examined. Further, we show that the carbon footprint of sevoflurane used in the NHS during 2018, in the absence of VCTs, is not smaller than that of desflurane if sevoflurane is synthesised from tetrafluoroethylene. Therefore, to reduce the carbon footprint of IAGs, this study supports the continued reduction in the use of nitrous oxide and recommends a wider adoption of VCTs.