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Member Spotlight: Dr. Elizabeth Hansen's Climate Efforts Are Heating Up


Over the past five years Dr. Elizabeth Hansen has made it a personal and professional goal to reduce the environmental impact of anesthesia. In this Member Spotlight, she gets granular about the various projects she's working on to help hospitals cut emissions and waste while saving on costs, too. 

How did you first become interested in the climate impact of anesthesia, what did you learn, and at one point did you decide to take an active role in addressing this issue at the professional level?
In 2019 I learned that 7% of my own hospital’s emissions were from anesthetic gases. This was the third largest contributor after natural gas and commuting related emissions and the only clinical category on the list. Our hospital has pledged to provide carbon neutral care by 2025 and I was really motivated to help us achieve that goal. I found a rich body of evidence in the literature from folks like Drs. Jodi Sherman, Brian Chesebro, Jeff Feldman, and Seema Gandhi, to name just a few. They have demonstrated the greenhouse gas (GHG) impact of anesthetic gases and the massive impact health care delivery has on the environment.
I decided to track our anesthesia related emissions in a more granular way than the annual reports. Calculations are already out there on how to convert inhaled anesthetics to carbon dioxide equivalents (like the app from Dr. Sherman’s group at Yale, Gassing Greener), and so we took the data we were already collecting from the anesthesia machine – fresh gas flows, percent exhaled gases, and converted them to carbon dioxide equivalents in kilograms per minute. We were able to pull that data into a software solution called AdaptX, which was developed by my colleague at Seattle Children’s, Dr. Dan Low. The software is very user friendly and allows anyone in our group to query data that is collected in the EMR. We have used this software to provide near real time data feedback to the group on our emissions as part of Project SPRUCE (Saving our Planet by Reducing Carbon Emissions). Our interventions included a socialization phase, formal and informal education of staff and trainees, practice constraints like removal of desflurane vaporizers and unplugging nitrous oxide hoses, promoting low flow anesthesia with changing default fresh gas flow settings, and adding a clinical decisions support tool, and providing real time data feedback to each provider on their own emissions. With Project SPRUCE, we are able to identify high emission cases, surgical specialties, and patient demographics, with the goal of implementing strategies to reduce emissions further. We reduced our emissions from inhaled anesthetics in the operating rooms by 87% and saved our hospital $140,000 a year in anesthetic gas costs. This work was published in Anesthesia and Analgesia.
Pictured: Example of low flow (0.35L/min) with use of Flow Wizard on the Drager Perseus

In addition to working as a pediatric anesthesiologist at Seattle Children's Hospital, you also serve as Chair of its “Peri-op Green Team.” What’s the mission of this team and what is it doing to achieve its goals?
I formed the Periop Green Team with colleagues in the ORs and perioperative space because so many of them came to me with ideas on how to reduce the environmental impact of our care. PACU nurses had ideas about reusable monitor components, surgeons wanted to reduce unnecessary waste from their surgical packs, anesthesia techs wanted education about recycling, anesthesia colleagues wanted to keep our reusable laryngoscopes instead of switching to the more environmentally harmful disposable ones, and OR nurses wanted to be able to wear their cloth scrub caps instead of disposable buffonts. I wanted to help each of them with these issues, and realized we had to organize ourselves to get this work done effectively. 
We now have 70 members, including techs, nurses, physicians, NPs, administrators, and child life specialists. We are supported by the hospital wide Green Team and Sustainability staff. We provide education on recycling, perform waste audits, work with purchasing on sustainable supply chain, update hospital policies (like allowing cloth scrub caps!), and participate in annual DrawDown Eco Challenges. Next month we are going on a tour of the recycling facility we contract with to see where our recyclable materials actually go. We are also working with the hospital on decommissioning our centrally piped nitrous oxide system, which unfortunately contributes unnecessary waste and emissions from leaks from the cryotanks and pipe fittings. The vast majority of purchased nitrous oxide never actually reaches a patient due to these leaks. We are preparing our clinical teams to use portable E cylinders that can be closed in between uses and eliminate all that  waste. More information about these leaky systems can be found here.

There are some in the medical field who argue that the climate impact of inhalational anesthetics like desflurane and nitrous oxide are negligible compared to, say, the methane gas released by commercial farming operations. What do you say to colleagues who raise this point with you?
The climate crisis is a health care crisis. We are physicians, and our job is to care for our patients and to do no harm. We all have a role to play here, and we don’t have time to wait for others to solve their problems before we tackle our own.
Health care delivery itself weighs heavily on the environment, accounting for more than 5% of global GHG emissions. The United States emits the highest per capita health care emissions - if U.S. health care were a country, we would be the 7th largest emitter in the world. We must decarbonize and mitigate the massive impacts of health care related emissions and pollution. 
Climate change is occurring at an unprecedented rate. We are experiencing record heat waves, wildfires, floods, droughts, and re-emerging infectious diseases fueled by global warming. We face a very bleak picture for human health without rapid efforts on all fronts. Climate crisis is impacting human health on a large scale and those least responsible for the crisis tend to bear the brunt of the effects. Children suffer an estimated 88% of the global burden of disease attributable to climate change.

Please tell us a bit more about Project SPRUCE and Project EVERgreen Forest. What are your biggest challenges right now? Progress and achievements?
My co-PI, Dr. Diane Gordon, and I expanded Project SPRUCE to other pediatric anesthesia groups, and we are calling that Project SPRUCE Forest. We currently have 10 centers using proven methods to reduce emissions from inhaled anesthetics by at least 50% over 12 months. Centers with data feeds coming in are already seeing major reductions in emissions with their efforts! 
We had so much interest from adult hospitals and anesthesia groups that we decided to launch Project Evergreen Forest. We are recruiting hospitals to join this consortium now. We continue to refine our methods and strategies for emissions reductions and track our progress with access to real time data. Each anesthesiologist can see their own emissions from the cases they did the month, week or even day before. They can see which cases have the highest emissions in order to target interventions in the most high yield areas. They can monitor balancing measures to ensure emissions reducing strategies do not impact clinical care overall (we found no changes in induction time, efficiency, PACU pain scores, PONV, and patient satisfaction). 

What’s next for you and your colleagues in the sustainability space? (Feel free to interpret that question however you’d like!)
At this point, we have the data, methods and tools at hand, so now we are working on the implementation piece. My dream is that every anesthesia department or group has a sustainability champion who leads the same types of efforts and commits to reducing emissions from our care. We are on the brink of a paradigm shift in anesthesia, as we change our practice using evidence based methods and providing the same (or better) safe, effective and excellent care for our patients. 

Is there anything you’d like to talk about that we haven’t yet touched on?
I want to talk about the term "climate justice" which reframes climate action from the effort to reduce GHG emissions to a framework that addresses human rights and social inequity. It highlights the disproportionate impact of the climate crisis on groups that are historically marginalized. Indigenous peoples and other minoritized racial and ethnic groups frequently face the worst environmental degradation.
Global warming and higher temperatures are associated with congenital cardiac anomalies, spina bifida, cleft lip and palate, and hypospadias. Severe heat and air pollution have been linked to preterm birth and low birth weight which can increase anesthetic risk. Wildfire smoke worsens respiratory illnesses and increases the risk of respiratory complications under anesthesia in vulnerable populations, as we have seen from work out of UCSF. 


  • Eckelman MJ, Huang K, Lagasse R, Senay E, Dubrow R, Sherman JD. Health care pollution and public health damage in the United States: an update. Health Aff. 2020;39:2071–2079
  • Romanello M, McGushin A, Di Napoli C, et al. The 2021 report of the Lancet Countdown on health and climate change: code red for a healthy future. Lancet. 2021;398:1619–1662
  • Gordon D. Sustainability in the operating room: reducing our impact on the planet. Anesthesiol Clin. 2020;38:679–692.
  • Kennedy RR, Hendrickx JF, Feldman JM. There are no dragons: low-flow anaesthesia with sevoflurane is safe. Anaesth Intensive Care. 2019;47:223–225
  • Seglenieks R, Wong A, Pearson F, McGain F. Discrepancy between procurement and clinical use of nitrous oxide: waste not, want not. Br J Anaesth. 2022;128:e32–e34
  • Sherman JD, Chesebro BB. Inhaled anaesthesia and analgesia contribute to climate change. BMJ. 2022;377:o1301.

Elizabeth Hansen, MD, PhD, is an assistant professor at Seattle Children’s Hospital and a faculty member in the Department of Anesthesiology and Pain Medicine at the University of Washington. She completed her residency at the University of Washington and fellowship training in pediatric anesthesia at Seattle Children’s Hospital. She is passionate about sustainability in anesthesia and efforts to green the operating room as part of her commitment to environmental justice and equity. 
She graduated from the Medical Scientist Training Program at Washington University in St Louis with her MD and a PhD in Molecular Microbiology and Microbial Pathogenesis.


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