During surgeries, medical professionals often turn to inhaled medications, including nitrous oxide (commonly known as laughing gas) and sevoflurane, to help patients cope with pain, among other surgical effects. And although volatile anesthetics are ubiquitous in operating rooms and other medical settings, they produce harmful greenhouse gas emissions. A study even found increasing concentrations of anesthetic gases in remote corners of the world, including Antarctica and the Swiss Alps.
Common anesthetic gases are much more potent than other greenhouse gases like methane and carbon dioxide. For example, carbon dioxide has a global warming potential of 1, whereas that of nitrous oxide is 289, sevoflurane is 440, isoflurane is 1,800, and desflurane is 6,810.
Many anesthesiologists are still unaware that they can prevent these emissions by swapping inhaled anesthetics for medications delivered intravenously, according to Nicolaas Sperna Weiland, an anesthesiologist at Amsterdam University Medical Center (AUMC) who advocated for reducing their use at the Euroanaesthesia Congress in June 2022.
“I don’t understand why people are still so in favor of the inhaled anesthetics,” said Sperna Weiland. “To my knowledge, there hasn’t been a single study that showed that volatile anesthetics were improving patient outcomes as compared to IV [intravenous] anesthetics,” he added.
Emissions from the health care sector make up a chunk of many countries’ total emissions.
“Health care in the Western world is approximately 5%–10% of the countries’ greenhouse gas emissions,” Sperna Weiland said. Within that fraction, anesthetic gas makes up 2%–5% of emissions associated with medical waste. It’s a relatively small amount compared with global emissions, and a 2011 study found that laughing gas, for example, is responsible for just 0.1% of emissions.
But “0.1% of a massive pie is still a large piece,” Sperna Weiland said. “You have a win-win situation where you could just as easily modify an appreciable amount of greenhouse gases.”
Anesthetic Options Beyond Gas
Sperna Weiland said uncomfortable side effects like nausea and vomiting are actually lower with intravenous anesthetics, and cardiovascular complications of surgery, such as heart attacks and strokes, are no higher than when gas anesthetics are used. In addition, regional anesthetics, such as epidurals, are linked to speedier, less painful recoveries and skirt the need for volatile or intravenous anesthetics. According to anesthesiologist Christopher Wu, who specializes in regional anesthetics at the Hospital for Special Surgery in New York, patient needs should continue to determine which type of sedation is used, but he agreed that alternatives to volatile anesthetics can benefit patients and the environment alike.
Switching to other types of anesthetics is not without downsides. According to Wu, one consideration about both intravenous and regional anesthesia is that “we’re using fewer gases, but we’re also using more of other substances—drugs such as propofol, or more plastic syringes,” he said. “What’s the environmental impact of that? That’s something we haven’t calculated yet.”
Sperna Weiland isn’t advocating for a wholesale ban on volatile anesthetics, either. Children, for example, may need an inhaled anesthetic prior to starting intravenous anesthesia. In addition, an anesthesiologist must administer IVs, a challenge for medical providers without regular access to such a specialist, such as those using medications like nitrous oxide for pain relief during dental procedures or childbirth.
Hospital “Green Teams” Cut Emissions
Some hospitals are taking action to cut emissions from volatile anesthetics and reduce waste. Sperna Weiland founded the Sustainable Healthcare Team to reduce medical waste at AUMC, and it was quickly dubbed the “green team.” The group worked to reduce operating room energy consumption and waste from surgical supplies. Hospital leaders supported the team’s efforts, abolishing the use of desflurane and nitrous oxide. Plus they began teaching anesthesiologists and anesthesiology residents to use sevoflurane in ultralow-flow settings, which the hospital found reduced the annual number of canisters of gas it used by 70%.
AUMC isn’t alone in its efforts. The European Union is creating legislation to ban desflurane starting in 2026. It will likely be the first medication to be banned because of climate change. Anesthesiologists like Wu also expect demand for inhaled anesthetics to decrease over time as consumers begin to seek out sustainable health care. “More and more hospital systems will see that sustainability is important as part of their operating package,” he said, “not only for patient care but also, frankly, [for] the bottom line.”
—Robin Donovan (@RobinKD), Science Writer