Anesthesia for knee replacement surgery has considerable carbon footprint

Overall estimated average CO2 emissions were similar, with significant overlaps, across the three groups: 14.9 kilograms (kg) CO2 for general anesthesia, 16.9 kg for spinal anesthesia, and 18.5 kg for combination anesthesia. In all groups, major sources of CO2 emissions were:

• Single-use (disposable) items, mainly plastics: 20% to 25% of total emissions
• Electricity for the patient air warmer: about 15% of emissions
• Pharmaceutical products (other than anesthetics): 8% of emissions

Some sources varied by anesthesia type. Sevoflurane accounted for 32% of total emissions in the general anesthesia group and 17% in the combined group. Washing and sterilizing reusable items contributed 25% of emissions with spinal anesthesia and 20% with combined anesthesia. Oxygen accounted for 15% of the carbon footprint of spinal anesthesia.

Based on the fuel efficiency of the average U.S. car, carbon emissions from anesthesia for one knee replacement surgery is equivalent to driving 42 miles, the researchers estimate. They note that the carbon footprint of anesthesia likely varies between countries. For example, in Australia, where they still rely heavily on coal to produce electricity, indirect emissions are greater than in Europe or the U.S.

Dr. McGain and coauthors outline steps anesthesiologists can consider to safely provide anesthesia while reducing their carbon footprint: lowering oxygen flow rates for spinal anesthesia, reducing inhaled anesthetic use, minimizing plastic and glass use, and advocating for renewable energy production. "When combining these carbon-sparing activities, you've halved the miles driven for the 3-hour anesthetic (typically required for knee replacement surgery)," the researchers wrote.

The researchers concluded, "We encourage cognizance of one's carbon footprint, emphasizing that instigating multiple, seemingly small changes in our workplace patterns is the best path to low carbon anesthesia."