By: Adam Cassella, DO, Wayne State University
Daniel Applefield, MD, Wayne State University and Anesthesia Associates of Ann Arbor
In 2020, the American Society of Anesthesiology (ASA) enacted an initiative to decrease the overall carbon footprint of operating room waste. The current practice of waste anesthetic gas (WAG) product removal is via rooftop ventilation. Unfortunately, this method of WAG removal has contributed a significant amount to the current climate crisis. Of note, if the global medical care facilities were a country, it would be the fifth-largest carbon emitter on the planet. (1,2).
Halogenated compound waste contributes to 11% of global warming. On a molecular level, atmospheric global warming and heat retention occurs when halogenated compound waste absorbs energy in the presence of infrared light. The absorption and emission of the infrared light potential of these molecules is defined as the global warming potential (GWP). The GWP is often measured over 100 years (GWP100). This metric is a comparison to the radiative forcing of a substance compared to CO2 (3). For example, CO2 has a GWP of 1 (4). The GWP’s of nitrous oxide (N2O), sevoflurane, isoflurane, and desflurane, measured in kilograms, are 265, 510, 130, and 2540 respectively (5).
Due to the elevated GWP of desflurane, it is by far the worst offender and contributor to greenhouse emissions of all the anesthetic gases. On average, each bottle of desflurane contains 240 ml of vapor and 893 kg of anesthetic gas in liquid form (6). Therefore, since each kg of desflurane creates 2540 kg of GWP100 of emissions, the damage produced to the atmosphere is significant. It has been determined desflurane is responsible for 80% of the greenhouse effect from volatile anesthetics (7).
Anesthesiologists can reduce the environmental impact general anesthesia contributes to the environment in a multitude of ways. Research has concluded simple practices such as reducing fresh gas flow (<1 L/min), avoiding the use of desflurane and nitrous oxide, utilizing total intravenous anesthesia, and considering regional and/or neuraxial anesthesia when appropriate, can not only decrease greenhouse gas emissions but also elicit a significant cost savings (8,9,10). These interventional techniques have been encouraged by the ASA Task Force on the Environment.
Our anesthesia department here at St. Joseph Mercy Oakland, in Pontiac, Michigan, decided to take on the task of reducing our greenhouse emissions. We began with removing the desflurane vaporizers from the anesthesia machines in the operating room and placed them in the department’s anesthesia supply room. Although the vaporizers were removed from the OR, they were still available to our anesthesia providers should the anesthesia care plan warrant its use for a particular patient. The mere fact that our vaporizers were no longer at the fingertips of our providers lead to a significant impact on decreasing our overall use of desflurane since the time of implementation. Prior to implementing this change, we undertook a corporate-wide educational initiative amongst our anesthesia providers to better understand the science behind our initiative. This helped providers be more receptive to
the proposed clinical change.
In 2019 our institution utilized 150 Desflurane Units which made up 20% of our volatile anesthetic use when compared to sevoflurane at 80%. The supply chain purchased 49 boxes of desflurane containing 6 bottles each for a cost of $19,479.45. In 2020, desflurane was only 5% of our volatile anesthetic use compared with sevoflurane at 95%. A total of 42 units of desflurane were utilized. Our purchasing department received 6 shipments each containing 6 bottles for a total cost of $3,653.21. There is no doubt that a portion of the reduction in desflurane utilization was, in part, due to the COVID 19 pandemic. This was particularly evident due to the reduction of operating room case volume for the months of March and April.
However, we believe our downward trend in desflurane usage has continued due to the small change implemented within our department.
Although our utilization of desflurane has decreased, there are other steps we as a department can explore to decrease our carbon footprint. The ventilation of our WAG’s continues to be a problem. There are commercially available WAG capture and destruction technologies that are in use in other countries that can assist in reducing one’s carbon footprint. Another possible solution is the use of a circuit UV lamp which has some utility in destroying both volatile anesthetics and, a lesser extent, N2O (11,12). Obviously, further cost benefit analysis is needed to evaluate these other available technologies before considering implementation. After our greenhouse effect reduction and cost saving potential was realized, we encouraged the implementation of our model on a corporate wide scale with other sites achieving the same endpoint.
We encourage all other Trinity Health sites nationally to consider some of the measures we have undertaken to reduce greenhouse emissions.
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