General anesthesia, an anesthetic used to induce unconsciousness during surgery, is being administered to about 50 million patients every year in the US alone. Anesthetic gases and vapors are likewise used in veterinary clinics, dentists’ offices, and lab for animal research. But anesthetics use halogenated compounds that are destructive to the ozone layer and have a potential impact on global warming. Changing how we anesthetize people could, therefore, have a surprising effect on the planet, according to Science Alert.
Impact of anesthesia gases on the ozone layer
The gases, like desflurane and nitrous oxide, that put patients to sleep during surgery are not always well understood in terms of their effects on the atmosphere. Previous studies have shown that these gases have an atmospheric lifetime of 114 years, damaging the ozone layer and amplifies climate change.
In a new study that appeared in BMJ Journals of Regional Anesthesia, authors Mausam Kuvadia from Hospital for Special Surgery in New York, USA and colleagues explained that following general anesthetics, the nitrous oxide and halogenated agents are exhaled by the patient, scavenged from the operating room, and then released into the atmosphere. During 114 years, they contribute to ozone destruction and climate change.
The switch to regional anesthetic
To prevent global warming and reduce greenhouse gas emissions, Kuvadia and the team suggest the use of regional anesthesia and avoiding the use of volatile inhalation agents. A significant amount of global greenhouse emissions will be reduced if hospitals use regional anesthetic whenever possible.
While general anesthesia causes a person to fall asleep while the medical procedure happens, local anesthesia is applied to a certain region of the body only where the procedure will be performed. Local anesthesia numbs a small area of the tissue where the minor procedure is to be done. On the other hand, regional anesthesia numbs a larger, but still limited, part of the body and does not make the patient unconscious. Epidural and spinal anesthesia are examples of regional anesthesia.
The new study used a hospital in New York as a real-world example. The researchers then estimated what happens to the facility’s greenhouse gas emissions when surgeons perform under regional anesthetic. The Hospital for Special Surgery in New York also conducted more than 10,000 regional anesthetic procedures in 2019. That year, only 4% were done under general anesthesia compared to an average of 75%.
The authors said that change alone in 2019 saved nearly 12,000 kg. of coal burned or more than 97,365 km. of driving. Put differently, the switch could have fully charged more than 3 million smartphones.
The study also emphasized that the gases have an “extremely high global warming potential.” The use of desflurane in one hour alone is already equivalent to driving 470 miles. The authors added that compared to other benefits described using regional anesthesia, the benefits of the present case are global. They added, though, that the decision to use a certain anesthetic method should still be based primarily on the optimal technique for the patient. Not all surgeries can be performed under regional anesthesia, which often relies on intravenous sedatives instead of gas. Not all general anesthesia are also gases.
It should likewise be noted that the research was based on one hospital only in the US. It does not consider the whole transportation and production of emissions needed for anesthetic. If the results are expanded nationwide, the potential use of regional anesthetic for global warming prevention seems clear.
The study was co-authored by Cynthia Eden Cummis of World Resources Institute, Gregory Liguori, and Christopher L. Wu, both from the Hospital for Special Surgery.
Patient safety as a priority
Christian Bohringer, MD, who was not involved in the study, also said that when making decisions about how they practice medicine, anesthesiologists should always prioritize patient safety over any environmental or monetary considerations. Nevertheless, as an anesthesiologist himself, he said that they have the obligation and opportunity to contribute to the efforts that consider the environmental impact of their daily working activities.
Aside from limiting greenhouse gas emissions due to anesthesia, another big area that affects the environmental footprint of anesthesiology is reducing medical equipment waste. Over time, their specialty has moved to use disposable polyvinyl chloride (PVC) ETTs instead of re-usable rubber ETTs. The use of disposable equipment was driven by the potential risk of nosocomial cross-infection and cross-contamination.
Number of active physicians in the US, 2020
According to database company Statista, there are 50,837 anesthesiologists in the US as of June 2020. Other active physicians included in the data includes those who specialize in psychiatry (55,593), surgery (55,593), emergency medicine (57,834), radiology (48,464), cardiology (33,055), oncology -cancer (20,886), endocrinology, diabetes, & metabolism (8,237), all other specialties (207,022).
Global warming potential (GWP) of halogenated anesthetics
As the world population grows and as modern anesthesia becomes more available to different regions of the world, the worldwide use of anesthetics will also rapidly grow. In a 2011 study titled General Anesthetic Gases and the Global Environment, author Yumiko Ishizawa from the Department of Anesthesia, Critical Care and Pain Medicine of Harvard Medical School mentioned that at present, most anesthesia systems used in hospitals and laboratories transfer waste gases directly into the atmosphere. Scavenging systems have been introduced to reduce the spillage of general anesthesia into the operating room but plenty is still exhausted into the planet, leading to ozone depletion. The GWP of halogenated anesthetics ranges from 1230 isoflurane to 3714 desflurane times the GWP of CO2.
Meanwhile, scientific online publication Our World in Data shares that the US has emitted more CO2 than any other country to date. It is responsible for 25% of historical emissions in the world and twice more than China, which is the world’s largest national contributor. Relative to its population size, Africa’s regional contribution to global Co2 emissions has been very small. The 28 European Union countries are also a large historical contributor to CO2 at 22%.
Hence, the use of regional anesthesia not just improves the quality of care for the patient but is also good for the planet. Individual practitioners may take responsibility in the world’s fight against global warming.