Cite as: Outterson R. What do we know about the environmental benefits of regional anesthesia? ASRA Pain Medicine News 2023;48. https://doi.org/10.52211/asra050123.006.

The global medical community has taken notice of the climate crisis. In September 2021, 200 medical journals joined together to simultaneously publish an editorial beseeching world leaders to “keep average global temperature increases below 1.5° C, halt the destruction of nature, and protect health”.¹ In recognition of the contribution healthcare itself makes to greenhouse gas (GHG) emissions, a group of 61 hospital systems and healthcare-related companies in the United States have recently signed the Health Sector Climate Pledge to reduce GHG emissions 50% by 2030.² Where will these reductions come from?

A group of 61 hospital systems and healthcare-related companies in the United States have recently signed the Health Sector Climate Pledge to reduce GHG emissions 50% by 2030.

To start, we can look no further than our own operating rooms. The administration of anesthesia adds markedly to the carbon footprint of surgical care. Anesthetic gases can contribute 50% of the life cycle GHG’s for a surgical procedure and may be responsible for 5% of the emissions of an entire hospital.³ Much of this depends on the individual choices made by anesthesia providers. With a twist of the desflurane vaporizer or the nitrous oxide knob, anesthesiologists may increase the GHG emissions of their anesthetic by orders of magnitude.⁴

Global anesthesia societies, including the American Society of Anesthesiologists, the Association of Anaesthetists, and the Canadian Anesthesiologists’ Society, have published recommendations for sustainable practice of anesthesia.^5,6,7 These include using low fresh gas flows, avoiding desflurane and nitrous oxide, and minimizing pharmaceutical and single-use plastic waste. And, of course, each of these societies recommends using regional anesthesia. At its most basic, requiring very little in the way of supplies, regional anesthesia seems like it would tread lightly upon the earth. But how much do we know about the environmental benefits of regional anesthesia? Here’s the evidence we have:

1. Epidural analgesia has a lower carbon footprint than nitrous oxide for labor. A life cycle analysis of methods of labor analgesia in the United Kingdom showed epidural analgesia to be the clear winner when compared with intermittent inhalation of nitrous oxide over a 4-hour labor.⁸ The overall carbon emissions were 200-fold lower for the epidural group. The carbon footprint of remifentanil patient-controlled analgesia (PCA) was also compared and found to be 65% of that for epidural analgesia over the course of a 4-hour labor. However, over 70% of the carbon footprint of an epidural was owing to the disposables used in its placement, whereas the continuous oxygen administration required for remifentanil PCA meant its carbon footprint continued to rise with continued administration. Therefore, over a more prolonged labor, epidural analgesia would have a lower carbon footprint than remifentanil PCA.
2. We think spinal anesthesia has a lower carbon footprint than general anesthesia for arthroplasty. In 2020, a group at the Hospital for Special Surgery (HSS) published a daring discourse positing that their performance of 96% spinal anesthesia for arthroplasties avoided anesthetic gas emissions equivalent to 60,500 miles driven by car.⁹ Based on anesthetic gas avoidance alone, a group from the University of Alberta further calculated that, if HSS’s 96% spinal rate were adopted, it would save 40-240 tons of carbon dioxide equivalent emissions per year.¹⁰
3. But…it’s complicated. An observational study published in 2021 of the practices at the University of Melbourne found no significant difference in the carbon footprint between spinal and general anesthesia for total knee replacement. However, on closer examination of the data, more than half of the carbon footprint of a spinal anesthetic in this study was from electricity, particularly its use in patient warming, equipment sterilization, and oxygen delivery. With a longer operating room time owing to spinal placement in the room, electricity for warming was run for 20% longer in spinal cases than general anesthesia cases. Oxygen administration, which was run at significantly higher flows for spinal anesthetic cases than for general anesthetics (6-10 L/min vs. 0.5-3 L/min), further added to the electricity cost of spinal anesthesia over general. Given Melbourne’s 75% coal-based electric grid, this electricity had a particularly heavy carbon footprint. The authors recalculated their findings using the electricity mix of the United States and European Union, both of which resulted in a slightly lower carbon footprint for the spinal anesthetic than the general anesthetic.¹¹ Presumably, a few differences in practice, such as skipping the sterile gown for spinal placement and lowering supplemental O2 flows, would further solidify spinal anesthetic as the more sustainable option in settings with electricity from more renewable sources. Practice changes to maximize the sustainability benefits from regional anesthesia are outlined in the infographic published in this issue of ASRA Pain Medicine News.

Though not explicitly studied, many of the other benefits of regional anesthesia may translate into environmental savings. For example, ambulatory hip and knee arthroplasty patients having spinal anesthesia have a higher rate of successful same-day discharge compared to those having surgery under general anesthesia (77% compared to 67%).¹² Given the electricity and resources utilized in an in-patient hospital stay, this 10% increase in successful discharge may represent a significant savings of emissions. In cases where a regional anesthetic cannot be the sole anesthetic, we commonly note that placement of a preoperative block can reduce the amount of inhaled anesthetic required, thus decreasing the GHG emissions from anesthetic gas. And, of course, regional anesthesia can help better control postoperative pain,¹³ may decrease the incidence developing chronic postoperative pain¹⁴, decreases the risk of postoperative delirium in the elderly¹⁵, increases the likelihood of AV fistula patency at 3 months,¹⁶ and decreases the likelihood of a myriad of complications after primary knee and hip arthroplasty.^17,18 In each of these cases, the benefits of regional anesthesia may translate into decreased resource utilization and therefore a lower carbon footprint of not just a single anesthetic, but a patient’s entire perioperative course.

At the recent ASRA Pain Medicine Green SIG symposium in October, E.B. Fouts-Palmer, MD, shared a slide facetiously titled “So, if we just use regional anesthesia for everything that should solve all our problems, right?” The reality, she was quick to point out, is more complex. While regional anesthesia alone does not guarantee a lower carbon footprint, it is certainly part of the solution. And while the literature on this topic could benefit from some filling out, we do know enough to use regional anesthesia in ways that decrease the carbon footprint of our practice right now. Regional anesthesia carries many benefits for our patients and, if we do it right, the benefits for the planet will likely become clearer with time.

Rachel E. Outterson, MD, is a clinical assistant professor of anesthesiology, perioperative, and pain medicine at the Stanford University School of Medicine in Stanford, CA.

References

1. Atwoli L, Baqui AH, Benfield T, et al. Call for emergency action to limit global temperature increases, restore biodiversity, and protect health. N Engl J Med 2021;385:1134-7. https://doi.org/10.1056/NEJMe2113200
2. Health sector leaders join Biden Administration’s pledge to reduce greenhous gas emissions 50% by 2030. The White House. https://www.whitehouse.gov/briefing-room/statements-releases/2022/06/30/fact-sheet-health-sector-leaders-join-biden-administrations-pledge-to-reduce-greenhouse-gas-emissions-50-by-2030. Published June 30, 2022.
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15. Yoshimura M, Shiramoto H, Koga M, et al. Comparing the effects of peripheral nerve block and general anesthesia with general anesthesia alone on postoperative delirium and complications in elderly patients: a retrospective cohort study using a nationwide database. Reg Anesth Pain Med 2022;47(9):521-6. https://doi.org/10.1136/rapm-2022-103566
16. Macfarlane AJR, Vlassakov K, Elkassabany N. Regional anesthesia for vascular surgery: does the anesthetic choice influence outcome? Curr Opin Anaesthesiol 2019;32(5):690-6. https://doi.org/10.1097/ACO.0000000000000781
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