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Mass General tries performance reports to cut greenhouse gas use in anesthesia


By Martha Bebinger

January 10, 2023

Source: WUBR Photo / Image Source: Unsplash, Marcelo Leal Dr. Sam Smith was on call at a Santa Barbara hospital in January 2018 when mudslides killed 23 people. Over the next few years, Smith, an anesthesiologist, helped treat patients suffering injuries or illnesses tied to heat waves and fires in California.

“Climate change was really on my personal agenda,” said Smith. He bought an electric car, installed solar panels and cut back on meat. “I thought, wow, I’m really making a difference.”

Then Smith saw some research on the global warming impact of the anesthetic gasses he uses every day at work. Eight hours of using the gas desflurane would be like driving 1,600 miles in one of the cars Smith used to own. The calculation for nitrous oxide, or laughing gas, was about 270 miles.

“You see these numbers that are just astounding,” said Smith, who now practices at Massachusetts General Hospital. “There’s probably no other speciality that can make such a dramatic impact with so little change or effort.”

Smith’s primary gas is now sevoflurane. He says it is equally effective if not better for patients — and is more like driving 32 miles during a shift. Smith also reduced the amount of gas he gives patients, in line with national guidance. He started looking into anesthetic options that don’t use a greenhouse gas, and numbing parts of a patient’s body instead of using general sedation.

At Mass General, Smith co-founded a committee to discuss changes for the anesthesiology department as a whole. Nurse anesthetists and anesthesiologists were already getting monthly performance reports that showed how well they avoided low blood pressures during surgery and postoperative nausea. Now, they also see two climate assessments: The global warming footprint of the gasses they choose and whether they are reducing the flow, or amount of gas used.

A sample of the information clinicians receive, in this case about how much gas they are using. (Image courtesy Mass General Hospital and the Multicenter Perioperative Outcomes Group at the University of Michigan)These climate measures are a key step in Mass General’s pledge to reach net zero emissions by 2050. The hospital’s latest assessment shows anesthesia accounts for 43% of its greenhouse gas emissions. That’s a higher percentage than at many other hospitals because Mass General has already taken steps to address its carbon footprint in other areas. For example, all of the electricity for the hospital's main campus now comes from renewable sources, most notably wind.

“If we want to mitigate that risk, whether it be climate change or other harms from environmental pollution, then tackling anesthesia has to be one of the few top priorities,” said Dr. Jonathan Slutzman, who directs the Center for Environment and Health at Mass General.

The anesthesiology effort has generated strong interest, but it's also led to hard questions, even from some who are enthusiastic about tackling global warming.

“If I was on the operating table, I’d want my anesthesiologist to worry only about my health and safety and frankly disregard any concerns about greenhouse gas emissions,” said Dan Schrag, a climate scientist at Harvard University.

Schrag, who runs Harvard’s Center for the Environment, says there are many ways doctors and nurses could have more impact on climate change than by worrying about which gas they chose or how much they use during procedures. They could make sure their patients are prepared for extreme weather. They could help educate the public about the need for major policy changes and collective action. Or they could press for more widespread use of anesthetic options that don’t involve greenhouse gasses.

“Just working on their own carbon footprints will have a more limited impact,” said Schrag. “This is too big a problem, and it’s a collective problem. It’s the entire world.”

Slutzman says many clinicians at Mass General are doing the outreach Schrag suggests. But he argues the anesthesia reports will help that department lead by example.

“Look, we’re the only profession that has a moral imperative not to be hurting people,” said Slutzman, who is an emergency room physician. "We shouldn’t be harming the patient in front of us. We shouldn’t be harming the patients around us in our communities." Mass General now purchases very little desflurane, the worst climate offender among the anesthetic gasses. And the hospital is asking anesthesiologists and nurse anesthetists to limit their use of nitrous oxide, which has nearly 300 times the global warming potential of carbon. But Dr. Lucy Everett, who co-founded the sustainable anesthesiology committee with Smith, says no one is telling clinicians they can’t use nitrous oxide if it’s the best choice for a patient.

“We’ve been very clear that the first priority is taking care of the patient,” said Everett.

There’s another concern related to nitrous oxide. A recent evaluation showed 90% of what’s delivered to Mass General leaks from the central supply system — only 10% of the gas the hospital purchases is actually used on patients. The hospital is testing a switch to individual tanks to help address this problem.

Auditing anesthetic gas leaks and asking doctors and nurses to consider the global warming potential of their work is relatively new. When Dr. Yasmine Tameze trained at Mass General, from 2016-2019, one of the hospital’s most respected anesthesiologists urged regular use of nitrous oxide to revive patients after surgery.

“I was taught that these were the most beautiful wake-ups ever and you should master how to do them,” said Tameze. Now, she says, it's a strategy that feels more taboo when teaching residents.

Adding nitrous oxide to the mix during surgery may also produce a modest increase in the risk of postoperative nausea. So Tameze is shelving that wake-up technique and using a more climate-friendly gas. She’s also reducing how much gas she gives a patient. That’s another trained habit the monthly performance reports are nudging her to break.

“My flows are still not as low as they could be I guess, but it’s hard, it’s very hard,” said Tameze. “I still get dinged on that.”

The reports are designed to spur some competition within an already competitive profession. There is some grumbling from clinicians who say they don’t like feeling shamed. But Liz Faber, a nurse anesthetist, says it had never occurred to her that she was contributing to global warming while putting patients to sleep or waking them up. She likes getting the information.

“This impacts much more than just the patient I’m taking care of now,” said Faber. “It feels like you’re making a difference that extends beyond your day-to-day practice.”

Few of Faber’s fellow anesthetists in the U.S. get individual reports about their performance in the context of climate change. The effort started with eight Providence hospitals in Oregon in 2017. Dr. Brian Chesebro says those hospitals have seen a 95% drop in greenhouse gas emissions linked to anesthesia. They’ve also cut costs by 80% because sevoflurane, one of the gasses that is better for the environment, is also cheaper.

“We’re talking about really significant emissions reductions and cost savings,” said Chesebro.

Dr. Elizabeth Hansen at Seattle Children’s Hospital says the monthly reports she began sending to anesthesia colleagues in December of 2021 are making a difference there too. With the emails, an earlier education campaign and new protocols, Seattle Children’s has cut greenhouse gas emissions associated with anesthesia by 87% as compared to five years ago.

Hansen says her colleagues feel an urgent need for change. Last fall, smoke from wildfires blanketed Seattle with some of the worst quality air in the world.

“People are really motivated to reduce the harm associated with health care and address the climate crisis because it’s a health care crisis as well,” she said.

Hansen is launching a national network of children’s hospitals that will show clinicians the climate impact of their work as a tool to curb greenhouse gas emissions.

Climate-based reports may also be spreading beyond anesthesia. Chesebro says the Providence hospital network is collecting emissions data associated with all of the equipment and supplies routinely used or wasted in an operating room. The idea is to answer questions like: Does a surgeon order more disposable supplies or sterilized equipment trays than he or she needs? How much unnecessary trash is generated?

Using this approach, Providence is assigning a carbon score to every physician who performs gallbadder surgery, one of the more common procedures. Chesebro says clinicians don’t want to be told what they can or can’t do, but they embrace a debate about their choices.

In anesthesia “we’ve created an army of advocates who are hungry for the next project and excited to celebrate their success,” he said.


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