Switching from inhaled to intravenous general anaesthesia

Dear Editor

Volatile anaesthetic agents are greenhouse gases, with high Global Warming Potentials (GWP). This has generated considerable interest in the anaesthetic community and driven a narrative that volatile emissions are contributing to climate change. Unfortunately utilisation of GWP to estimate the climate effect of short lived climate pollutants (SLCPs), which includes all volatile anaesthetics, is not supported by climate science (1).

Dame Julia Slingo, an eminent climate scientist and previous Chief Scientist at the Met Office, has examined the role that volatile agents play in climate change. She has come to a very different conclusion compared to the current orthodoxy that pervades the Anaesthetic community. I would like to draw the author’s and reader’s attention to two recent interventions that Dame Slingo has made:

A) Dame Slingo's keynote at the AoA Annual Congress in Edinburgh, "'What can anaesthetists do to help the environment? A climate scientist's perspective'. Dame Slingo's key messages were:

1) Anaesthetic gases have a vanishingly small effect on radiative forcing and the Earth's energy budget regardless of their high Global warming potential (GWP).
2) They have no climate impact.
3) CO2e (CO2 equivalence) i.e. the numbers used to estimate the climate effect of volatile emissions are deeply misleading and should not be used.
4) Volatile emissions do not contribute to NHS Carbon Footprints . The focus should be on real CO2 emissions.

Dame Slingo’s keynote is available for members to view on the AoA website.

B) A review article in the Anaesthesia sustainability supplement, “The science of climate change and the effect of anaesthetic gas emissions” J. M. Slingo and M. E. Slingo (doi:10.1111/anae.16189) (2).

This paper is mandatory reading for anyone interested in sustainable anaesthesia and states that:
1) Atmospheric concentrations of volatiles are minute.
2) Volatile atmospheric lifetimes are short (they are not going to accumulate).
3) The radiative forcing (heating of the climate) from volatile emissions is insignificant.

I would also highlight that Dame Slingo’s position is supported by an extensive literature in the climate science journals and the latest report from the International Panel on Climate Change (IPCC), which states ``GWP is not well suited to estimate the cumulative effect on climate from sustained short-lived climate forcer emissions´´(3).

The work of Dame Julia Slingo and Dr Mary Slingo discounts climate concern over volatile emissions. This naturally leads to a conclusion that TIVA may actually be less sustainable due to the large amounts of plastic used. By maintaining the dogma that volatile anaesthetic emissions are contributing to climate change the anaesthetic community may well be increasing actual CO2 emissions and in fact worsening climate change. There are many reasons to utilise TIVA as an anaesthetic technique, sustainability is not one of them. In fact selecting a volatile agent (including desflurane) is likely to be the most sustainable option.

1) Pierrehumbert RT. Short-lived climate pollution. Annual Review of Earth and Planetary Sciences 2014; 42: 341–79.
2) Slingo, J.M. and Slingo, M.E. (2024), The science of climate change and the effect of anaesthetic gas emissions. Anaesthesia. https://doi.org/10.1111/anae.16189
3) Intergovernmental Panel on Climate Change. Working Group 3(Mitigation of Climate Change) of IPCC 6th Assessment Report.2022.https://www.ipcc.ch/report/ar6/wg3/