Carbon Footprint of General, Regional, and Combined Anesthesia for Total Knee Replacements

Abstract

Background Health care itself contributes to climate change. Anesthesia is a “carbon hotspot,” yet few data exist to compare anesthetic choices. The authors examined the carbon dioxide equivalent emissions associated with general anesthesia, spinal anesthesia, and combined (general and spinal anesthesia) during a total knee replacement. Methods A prospective life cycle assessment of 10 patients in each of three groups undergoing knee replacements was conducted in Melbourne, Australia. The authors collected input data for anesthetic items, gases, and drugs, and electricity for patient warming and anesthetic machine. Sevoflurane or propofol was used for general anesthesia. Life cycle assessment software was used to convert inputs to their carbon footprint (in kilogram carbon dioxide equivalent emissions), with modeled international comparisons. Results Twenty-nine patients were studied. The carbon dioxide equivalent emissions for general anesthesia were an average 14.9 (95% CI, 9.7 to 22.5) kg carbon dioxide equivalent emissions; spinal anesthesia, 16.9 (95% CI, 13.2 to 20.5) kg carbon dioxide equivalent; and for combined anesthesia, 18.5 (95% CI, 12.5 to 27.3) kg carbon dioxide equivalent. Major sources of carbon dioxide equivalent emissions across all approaches were as follows: electricity for the patient air warmer (average at least 2.5 kg carbon dioxide equivalent [20% total]), single-use items, 3.6 (general anesthesia), 3.4 (spinal), and 4.3 (combined) kg carbon dioxide equivalent emissions, respectively (approximately 25% total). For the general anesthesia and combined groups, sevoflurane contributed an average 4.7 kg carbon dioxide equivalent (35% total) and 3.1 kg carbon dioxide equivalent (19%), respectively. For spinal and combined, washing and sterilizing reusable items contributed 4.5 kg carbon dioxide equivalent (29% total) and 4.1 kg carbon dioxide equivalent (24%) emissions, respectively. Oxygen use was important to the spinal anesthetic carbon footprint (2.8 kg carbon dioxide equivalent, 18%). Modeling showed that intercountry carbon dioxide equivalent emission variability was less than intragroup variability (minimum/maximum). Conclusions All anesthetic approaches had similar carbon footprints (desflurane and nitrous oxide were not used for general anesthesia). Rather than spinal being a default low carbon approach, several choices determine the final carbon footprint: using low-flow anesthesia/total intravenous anesthesia, reducing single-use plastics, reducing oxygen flows, and collaborating with engineers to augment energy efficiency/renewable electricity. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

The carbon footprint of hospital diagnostic imaging in Australia

“…For example, anaesthesia is a recognised carbon hotspot, 23 yet one MRI has approximately equivalent emissions to one gaseous general anaesthetic. 24 Thus far, however, the carbon emissions from imaging have received little attention.…”

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One Thousand Words...

“…For instance, opinions vary on whether it is safer to use plain white labels versus color-coded labels. 2 The use of prefilled syringes replaces the traditional errorprone process of placing several drugs into different syringes with a streamlined process whereby a manufacturer prepares numerous syringes of the same drug, while also incorporating standardized labeling. 3 Another practice is the use of label printers that legibly print the name and dose of the drug with a corresponding barcode that can then be scanned by a barcode reader before administration.…”

“…Thank you for the vivid cover art from Maria Koijck and Eva Glasbeek 1 that accompanied the pair of environmental pieces from McGain et al . 2 and Struys and Eckleman 3 in the December 2021 issue. While the discussion in the article 2 and editorial 3 of the carbon footprint of anesthesia help contextualize this issue, this cover art drives home the message in a striking fashion.…”

“…2 and Struys and Eckleman 3 in the December 2021 issue. While the discussion in the article 2 and editorial 3 of the carbon footprint of anesthesia help contextualize this issue, this cover art drives home the message in a striking fashion. Work such as McGain’s needs to be done to assess and document the impact of our current healthcare practices.…”