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Avoiding general anesthesia could reduce the climate burden of surgery

Nitrous oxide has a climate warming effect 289 times that of carbon dioxide
June 23, 2020

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In the effort to stop climate change, most of the focus is rightly on the biggest emitters of carbon dioxide such as transportation, manufacturing, and electricity generation. But many other aspects of daily life can be surprising sources of greenhouse gases—and may offer the potential for clean, quick cuts.

Take surgery, for example. General anesthesia uses volatile halogenated gases and nitrous oxide to knock patients out. Very little anesthesia gas is metabolized by patients, so when they exhale these gases enter the atmosphere—and may persist for up to 114 years.

Nitrous oxide has a climate warming effect 289 times that of carbon dioxide, and desflurane, another common anesthesia gas, is 3,714 times more potent than carbon dioxide. These gases also damage the ozone layer.

Granted, any given surgery only uses a little anesthesia gas. Putting a patient under for an average 2-hour knee or hip replacement surgery requires about 100 g of desflurane and 8 g of nitrous oxide—with a global warming potential equivalent to burning about 4 pounds of coal, researchers calculated in a paper published in the journal Regional Anesthesia and Pain Medicine.

But it all adds up. If the more than 1 million hip and knee replacements performed in the United States in 2009 used general anesthesia, the anesthetic gases used would be equivalent to 3,260,000 pounds of coal burned, or 7,350,000 miles driven in an average passenger car.

And there is an alternative: regional anesthesia, which combines intravenous sedatives and anesthetic drugs injected close to a nerve for pain relief.

Regional anesthesia is growing in popularity, but it’s not clear exactly how many surgeries are performed with this method. The researchers reviewed a large health care system dataset and found that at more than 400 U.S. hospitals over a four-year period, only 11 percent of knee and hip replacements were done with regional anesthesia alone.

In 2019, the researchers’ own institution, the Hospital for Special Surgery in New York City, made a special effort to perform knee and hip replacements with regional anesthesia when possible. Only 4 percent of 10,485 such surgeries at the hospital that year used general anesthesia.

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The researchers calculated that the avoided use of general anesthesia gases that year saved the equivalent of 26,900 pounds of coal burned or 60,500 miles driven.

Their calculations are not a complete picture of the climate impact of regional vs. general anesthesia. That would require a full life-cycle analysis capturing emissions related to the manufacture, transport, packaging, and disposal of anesthesia agents used in either case. Still, these rough calculations are impressive. And other studies suggest that at least half of the carbon footprint of a U.S. operating room comes from anesthetic gases.

The researchers say their study could also spark discussions about other ways to reduce greenhouse gas emissions associated with hospitals and health care systems. In fact, a small group of researchers are starting to examine the climate impact of health care, and advocating for more climate-friendly alternatives.

Of course, “the decision to use a specific anesthetic method should primarily be based on the optimal technique for that individual patient,” the researchers write. But studies have shown that regional anesthesia is associated with better pain relief, fewer side effects, and faster recovery from some surgeries.   

“Increasing the use of regional anesthesia is potentially good for the climate, improves the quality of care (at least for hip and knee replacements), and may allow individual practitioners to take personal responsibility in the fight against global warming,” the researchers say.

Source: Kuvadia M. et al.‘Green-gional’ anesthesia: the non-polluting benefits of regional anesthesia to decrease greenhouse gases and attenuate climate change.” Regional Anesthesia and Pain Medicine 2020. 


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