The Impact of Waste Anesthetic Gas on Climate Change

The Onion is a parody digital media organization that publishes satirical news articles on social media. This Instagram post not only illustrates their tongue-in-cheek approach to critical issues of the day, it also reflects the helplessness many of us feel about resolving climate change and global warming. This blog post is intended to raise awareness of the negative impact that waste anesthetic gas has on the atmosphere, and to present simple techniques that significantly reduce that impact, while reducing the cost of anesthesia and saving money for your practice.

First, let’s take a moment to review what all the fuss is about. The illustration on the left shows the high points of global warming as a result of greenhouse gases. Starting at the upper right hand corner and moving clockwise around the picture, you see:

  • The sun radiates heat onto the Earth
  • Some heat is released back into space
  • Some heat is retained by gases like water vapor
  • Extra heat is retained by ‘greenhouse’ gases.

Opinions vary on the amount of warming, the significance of warming, and the timeline for critical consequences from warming, but the scientific community generally agrees to the high points shown in this picture.

Waste Anesthetic Gases (WAG) exhausted directly into the atmosphere

The most prevalent greenhouse gas produced by human activity is carbon dioxide. Although anesthetic waste gas doesn’t compare to carbon dioxide by volume, it’s estimated to cause 10% of total global warming, so it’s certainly a player. Dr Jodi Sherman, whose positions at Yale University include Associate Professor of Anesthesiology, and Affiliated Faculty of Climate Change and Health Initiative expresses concern for the growing role waste anesthetic gas plays in global warming. “…And it’s just released into the atmosphere with no control,” she says. Anesthetic gases aren’t a part of the Paris Climate Accord, and Dr Sherman believes that waste anesthetic gases are exempt from regulation because they are considered ‘essential medicines’ by the World Health Organization.

Worldwide yearly sales of inhaled anesthetics total in the millions of liters. A busy midsize human hospital in the US might purchase about 1000 liters of inhaled anesthetics each year. This could yield the equivalent emissions of up to 1200 passenger cars each year from a single mid-sized human hospital. It’s estimated that the total global emissions of inhaled anesthetics are equivalent to 9.5 million tons of carbon dioxide annually. That equates to the emissions from one million cars.

Unlike the satiric Onion News report, listing impossible responsibilities for each of us to overcome global warming, we can actually do something about the growing impact of waste anesthetic gases in the atmosphere. And not only are they easy, they will also save our practices money along the way.

Dr Sherman says the ways to reduce emissions are clear: maximize the use of intravenous and regional anesthesia, and pay close attention to waste gas. “We know what we can do,” she says. “It’s just a matter of laziness.”

Dr Alan Zneimer, Chair of Anesthesia for Kaiser Permanente Medical Center in Northern California, believes it to be less about laziness and more about moving doctors out of their comfort zones. He says the biggest roadblock to transitioning to more sustainable anesthesia practice is moving doctors away from the way things have been done in the past. “Sometimes trying to do something new or different is a little scary,” he says.

We can take a broad look at the anesthesia habits we’ve formed and look for things that could be done differently. For instance, keep the gas machines on a weekly maintenance schedule to avoid leaks (you can do most machine maintenance yourself – it’s pretty easy), pressure check breathing circuits before every use, avoid box inductions, and avoid mask inductions. All of these steps will reduce pollution and save money.

The most effective way we can reduce the impact of waste anesthetic gases on the environment is to reduce the amount of gas we release into the atmosphere. The easiest way to do that is to examine the oxygen flow rates we use. Choose a rebreathing circle system breathing circuit as often as you can, because you can use much lower gas flows with a circle system. Seven to ten times lower gas flow rates in most cases. Start a conversation about non-rebreathing circuits and examine how the decision is made in your practice to use one. We’re all pretty comfortable with a more-is-better philosophy when it comes to oxygen, but is it? If most of the gas passing through a circuit goes directly into the atmosphere, and a percentage of that gas is unused anesthetic gas, then we’ve found a flaw in the more-is-better philosophy. There are some distinct advantages to reducing the oxygen flow rate, for the patient and for your practice. Without adding any level of risk to the patient, they stay warmer during anesthesia, it helps retain moisture, it’s an efficient use of anesthetic gas, and it costs less than the high flow rates of a non-rebreathing circuit. Low flow anesthesia also yields significant benefit by reducing the amount of waste gas released into the environment. Like I said, it’s easy and you’ll save money along the way.

In the United States and Canada, multiple groups have developed systems that can catch, clean, and recycle anesthetic waste gas for future use. One method uses condensation to recapture used gas. The device cools the gas down and returns the anesthetic to a liquid to be stored in metal drums. The liquid is then distilled into its pure form and could be repackaged, resold and reused. It’s a beautiful way to reuse and recycle, but still lacks FDA approval, and is still in the developmental stages. In the mean time, you can make a big difference simply by reducing your oxygen flow rate.

“Unless someone is urgently requiring care, and you don’t have time to think, we frequently have choices,” Dr Sherman says. When you have a choice, she says, it’s important to weigh the environmental impact. “It’s not the only decision factor, and it’s not the first decision factor, but it needs to be one of the things that we think about.”

Follow these links to read more:

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Ken Crump AAS, AHT is a writer and animal anesthetist, and writes Making Anesthesia Easier for DarvallVet, a division of Advanced Anesthesia Specialists.  He makes dozens of Continuing Education presentations on veterinary anesthesia and oncology across the United States and in Canada.  Ken retired from the Veterinary Teaching Hospital at Colorado State University in 2008.

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