How the ban on a general anesthetic medicine has highlighted its disastrous global warming effect

By Suja Mary James

Desflurane, a general anesthetic medicine, has been banned in several hospitals in Scotland making it the first country to take such a step for the environment. The initiative is gaining special attention in the medical field as many countries are expected to follow this now to protect the environment. The ban has highlighted the otherwise overlooked issue of how an anesthetic drug like “desflurane” is affecting the environment and contributing to global warming. 

The use of Anaesthetic drugs 

The anesthesiologist uses a wide variety of medicines ranging from mild sedatives to highly potent inhalational gases and muscle relaxants to keep the patient relaxed and pain-free during surgeries. During surgeries, the most commonly used anesthetic agents (N2O(g) and halogenated agents(l)) are administrated to the patients through a “breathing mask or tube, or given through an intravenous (IV)  line”. A small amount of these gases escape during the procedure (waste anesthetic gases, WAG) and frequent exposure to these gases creates serious occupational illness for medical professionals. Apart from such health issues, inhaled anesthetics significantly increase “healthcare-related emissions of greenhouse gases”.

The cause of concern

Recently, studies pointed out that most volatile anesthetics such as “N20 and highly volatile halogenated gases such as sevoflurane, desflurane, and isoflurane” act as greenhouse gases and sometimes facilitate ozone depletion. Volatile anesthetics are estimated to contribute 0.01-0.10%  of the total global carbon dioxide equivalent (CO2e) emissions. By sampling the volatile anesthetics in the atmosphere, it has been found that their accumulation is growing, especially desflurane.

Disastrous Desflurane 

Amongst anesthetic gases, desflurane is one of the most common, but also one of the most harmful. NHS claims that “desflurane has 20 times the environmental impact of other less harmful greenhouse gases and using a bottle has the same global warming effect as burning 440 kg of coal”. Volatile anesthetics that are inhaled go through very little in vivo metabolism and are unaltered when exhaled and are typically released into the atmosphere as waste anesthetic gases in most institutions.

It is estimated that Desflurane remains in the troposphere for 14 years, whereas isoflurane and sevoflurane remain for 3.2 and 1.1 years respectively. Desflurane has an estimated 26 times greater global warming potential than sevoflurane and 13 times greater potential than isoflurane, according to research by Ryan et al. In addition, this study calculated that 1 MAC hour of desflurane (at a fresh gas flow rate of 2 L/min) is comparable to traveling 400 miles in terms of global warming potential. Sevoflurane, in contrast, has a MAC hour that is only equivalent to 8 miles of driving. These stark contrasts demonstrate the disastrous environmental effects of desflurane as compared to sevoflurane.

A report by WION quoted that, Desflurane has the potential for 2500 times more global warming than carbon dioxide, and its outlawing in all NHS hospitals would reduce harmful emissions equivalent to powering 11,000 homes each year.

Usage has begun to decline

As per National Health Service England’s report, anesthetic and analgesic practices account for 2% of carbon footprints, and  “transforming anesthetic practices such as using alternative desflurane” can lower thus carbon footprint by 40%. To attain environmental sustainability within the anesthetic practice, the Association of Anaesthetists, the Royal College of Anaesthetists (RCoA), and NHS England jointly took initiatives “to reach net zero on its direct emissions, including volatile anesthetics, by 2040 and also to stop the use of desflurane, an environmentally harmful anesthetic agent, by early 2024”.

As per the BBC news report, desflurane usage has begun to decline in many hospitals throughout the UK and is no longer being used by 40 hospital trusts in England and several hospitals in Wales. 

Joel Matthews, a 2-year trainee working in orthopedics at Ninewells Hospital, Dundee Scotland responded to queries from CFC, “I am glad to see NHS Scotland leading the way to stop desflurane. We have now access to anesthetic agents safe for the environment  and for patients even for longer surgeries” 

Inhalers too

Like Desflurane, NHS took initiatives to reduce its carbon footprint by switching to Low-carbon inhalers. It is estimated that inhalers contribute 3.9% of the total carbon footprint of the NHS in the UK.  The carbon footprint (CO2e) of a patient’s inhaler regimen can range from 15 kg to 450 kg annually, depending on the inhalers used. The majority of these emissions are caused by the hydrofluorocarbon propellant used in metered-dose inhalers. 

The greatest environmental impact is caused by MDIs (Pressurised Metered dose inhalers) containing HFA227ea, followed by those containing HFA134e. Aqueous mist inhalers (Respimat) also have a similar impact. The two pMDIs with the greatest Global Warming Potential (GWP) are Ventolin® Evohaler, Flutiform®, and Symbicort® pMDI (HFA227ea) (HFA134a large volume SABA – contains more propellant).  To reduce the impact, replacing MDIs with dry powder inhalers will lower the emission by 18 times.

By 2025, NHS England’s long-term strategy aims to cut the organization’s carbon footprint by 51%. Finding new alternatives or banning drugs that have a high carbon footprint is essential. But finding solutions without compromising the human recovery rate is still challenging.  

Source:

1. https://www.bbc.com/news/health-64347191
2. https://www.aegisanesthesiapartners.com/common-medications-used-anesthesia/
3. https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/types-of-anesthesia-and-your-anesthesiologist
4. https://associationofanaesthetists-publications.onlinelibrary.wiley.com/doi/10.1111/anae.15785
5. https://journals.lww.com/anesthesia-analgesia/Fulltext/2021/10000/Environmental_and_Occupational_Considerations_of.2.aspx
6. https://www.england.nhs.uk/greenernhs/whats-already-happening/putting-anaesthetic-generated-emissions-to-bed/#:~:text=Amongst%20anaesthetic%20gases%2C%20desflurane%20is,burning%20440%20kg%20of%20coal.
7. https://csahq.org/news/blog/detail/csa-online-first/2022/05/16/rethinking-desflurane
8. https://pubmed.ncbi.nlm.nih.gov/20519425/
9. https://www.wionews.com/world/scotland-first-to-ban-anaesthetic-agent-having-global-warming-potential-568324
10. https://anaesthetists.org/Home/News-opinion/News/Joint-statement-on-NHSEs-plan-to-decommission-desflurane-by-early-2024
11. https://www.bjanaesthesia.org.uk/article/S0007-0912(20)30766-2/fulltext#:~:text=One%20potential%20advantage%20of%20desflurane,of%20consciousness%20and%20tracheal%20extubation
12. https://northeast.devonformularyguidance.nhs.uk/formulary/chapters/3.-respiratory/the-environmental-impact-of-inhalers#:~:text=Pressurised%20metered%20dose%20inhalers%20