Greener Gases 

Keck Medicine of USC is phasing out one of the most commonly used — and environmentally toxic — anesthetics for its surgeries, desflurane.

The discontinuation of desflurane is part of a universitywide effort to re-examine both USC’s and Keck Medicine of USC’s impact on climate change and to implement healthier, sustainable solutions whenever possible.

The operating room is one of the biggest — if not the biggest — waste generators in any hospital, says Arash Motamed, medical director for Keck Main Perioperative Operations and Keck Medicine of USC Sustainability.

“They’re very resistant to degradation; they stay in that environment for many years,” says Motamed, an associate professor and vice chair of clinical operations for the department of anesthesiology at the Keck School of Medicine of USC.

In June, the Association of Anesthetists noted the inconvenient truth about anesthetics.

It cited research showing that anesthetics are responsible for 0.1% of the world’s carbon emissions. At the hospital level, inhaled anesthetics make up more than 5% of acute hospital carbon emissions and 50% of perioperative emissions.

Anesthetics in the atmosphere

During a surgery with anesthetics, a patient breathes in an anesthetic gas, which circulates through the body and keeps the person unconscious. After the operation, the anesthetics are turned off, the concentration in the body decreases and the patient regains consciousness.

Keck’s operating rooms have three primary anesthetics, Motamed says. Each achieves similar effects but has different drawbacks.

Desflurane is very quick to come on and very quick to come off — that’s why people love it. But it’s expensive and horrible for the environment.

Aren Nercisian, anesthesiologist at Keck Medicine of USC

“Desflurane is very quick to come on and very quick to come off — that’s why people love it,” says Aren Nercisian, an anesthesiologist at Keck Medicine of USC. “But it’s expensive and horrible for the environment.”

Desflurane is the most commonly used. Yet, studies show desflurane is so harmful to the environment that an eight-hour surgery causes as much damage to the atmosphere as driving a car from Los Angeles to Maine.

“The contribution to emissions is huge,” said Howard Hu, holder of the Flora L. Thornton Chair in Preventive Medicine and chair and professor of population and public health sciences at the Keck School of Medicine of USC. “That insight became a clarion call for us to do something about it.”

In its own call to action on pollution reduction, the California Society of Anesthesiologists noted that desflurane lingers the longest of any anesthetic — 14 years — in the atmosphere’s lowest layer, the troposphere, just above the Earth’s surface. On the other hand, sevoflurane remains in the troposphere for just over a year while isoflurane lingers for 3.2 years.

Helping the environment, cutting costs

Global warming potential (GWP) is a way to quantify the amount that an agent contributes to global warming over a period of time. Nercisian, who leads sustainability efforts for the anesthesiology department at Keck Medicine of USC, explains that GWP measures how much energy the emission of 1 ton of a gas will absorb over a given period, relative to the emissions of 1 ton of carbon dioxide.” The larger the GWP, the more it warms the Earth compared to carbon dioxide. The GWP of carbon dioxide is 1.

Desflurane has a 20 times higher global warming potential than sevoflurane, Nercisian says.

Desflurane has the highest global warming potential — 2,540 — compared with sevoflurane, which has a GWP of 130.

The triple aim of a health system should be improving patient experience, improving the health of the population and reducing the cost of health care … sustainable delivery of care should be the fourth aim.

Arash Motamed

The three also differ in cost. Desflurane tends to be the most expensive. And so far, no studies have indicated whether one is worse for patients than the others.

“There’s never been a study to prove that you have better outcomes with sevoflurane vs. desflurane vs. isoflurane,” Nercisian says. “Though some agents have specific advantages.”

Keck Medicine of USC has not ordered more desflurane in the past year.

“According to the Institute for Healthcare Improvement, the triple aim of a health system should be improving patient experience, improving the health of the population and reducing the cost of health care,” Motamed says. “Howard Hu, chair of Population and Public Health Sciences at USC, says that sustainable delivery of care should be the fourth aim. I couldn’t agree more.”