Pssst: Before reading this, consider closing the doors, covering the windows and scanning your office, phone, and computer for listening devices…I am going to let you in on a secret…climate change is real and unless we start acting immediately and with a sense of purpose, our, our children’s, and our grandchildren’s lives and well being are at stake, because we and they will be doomed if we don’t reverse course. A key contributor to climate change is the emission of greenhouse gases (GHGs) among which includes the release of waste anesthetic gases (WAGs) from surgical procedures into the environment. These anesthetic gases may also pose a potential health risk to us and other OR and PACU personnel. This very timely article is so important that I’ve asked Dr. Diane Gordon of the Children’s Hospital Colorado to weigh in and offer her thoughts as well. Diane has been at the forefront of thinking about these issues as well as how to reduce other medical waste, like disposable laryngoscope handles and the batteries they contain. I mean what idiot came up with that mandate? But I digress. Myron Yaster MD
Original article
Varughese S, Ahmed R. Environmental and Occupational Considerations of Anesthesia: A Narrative Review and Update. Anesth Analg. 2021 Oct 1;133(4):826-835. PMID: 33857027
Associated Infographic (at bottom of PAAD)
“A key contributor to climate change is the emission of greenhouse gases, which includes release of waste anesthetic gases from surgical procedures into the environment. Although anesthesia gases contribute a relatively small portion of GHGs (<0.1%), a strong body of evidence supports the importance of minimizing WAG release into the environment to limit contributions to climate change and associated health risks on the global level and, on an individual level, to minimize occupational exposure and risk of adverse effects”. I (DG) would wager there are very few occupations that can pinpoint their GHG emissions this specifically and if they could their contributions would be several orders of magnitude smaller! 0.1% doesn’t sound like much but we’re talking about 5.6 million tons of eCO2 emitted by US anesthetics annually- an amount we could (and should) easily reduce without affecting patient care in any way.
We’ve copied table 1 which lists the photophysical properties of anesthetic gasses.
To put this into some perspective, we can compare our use of anesthetic gases to driving a car. Thus, the emissions generated during a MAC-hour with desflurane is equivalent to those of a car that drove 189 miles, while the same hour with sevoflurane is equivalent to driving the car just 4 miles! Adding nitrous oxide makes this even worse. And yes, you read that right: “Because N2O is both an ozone depleter and a green house gas with an atmospheric lifetime of 114 years, use of N2O as a carrier gas versus air/oxygen substantially increases the global warming effects of sevoflurane and isoflurane!” Further, desflurane is a real problem too. “Compared with sevoflurane and isoflurane, desflurane has much higher life-cycle GHG emissions (15 and 20 times higher, respectively), owing to a combination of higher required concentration and higher radiative forcing effect”. Based on this, a “key recommendation of the ASA is avoid both N2O and desflurane and minimize fresh gas flow (FGF) rates to the absolute minimums” unless use of either could reduce morbidity and mortality compared with other anesthetics”. New and old technologies may help reduce waste anesthetic gases. The authors mention closed filling systems for vaporizers, low-flow techniques, automated control (versus manual control) of end-tidal anesthetic gases and potential photochemical exhaust gas destruction systems. The authors also speculate that adding a charcoal filter at the end of a case will not only hasten wake up but help minimize pollution of the ORs and PACUs. We think this later idea is a pretty interesting one and we would encourage one or many of the readers of the PAAD to study this.
Diane and I know that some of you are climate skeptics and minimize the effects of anesthetic gases in this process. After all, inhaled anesthetics make up < 0.01% of green house gases. Like speaking to anti-covid vaxxers, there’s nothing we can write or say that will sway you. However, the second half of this article discusses the effects of occupational exposure and potential impact and should be of concern to every one of us. I (DG) am embarrassed to say I was unaware that OSHA and NIOSH have published very specific levels of acceptable volatile anesthetic exposure… “Occupational exposure to halogenated anesthetics agents should not exceed 2 ppm or N2O >25 ppm within a 1-hour period (time-weighted average for exposure duration) and that anesthetic gas machines, nonrebreathing systems, and T-tube devices must have effective scavenging devices to collect all waste anesthetic gases”. As pediatric anesthesiologists this is easier said than done. Just think about induction and emergence, particularly if using a deep extubation technique! Although WAG scavenging and efficient air handling in the OR are mandated by law, the air handling of the PACU is not required to be as robust. And fhuggetabout regulations in non-operating room anesthetic locations! It is very possible that our exposure may exceed recommended limits. Also, according to the article, “NIOSH recommends obtaining baseline values and periodic monitoring of hepatic and renal function for exposed personnel as well as documentation of pertinent medical history information such as pregnancy outcomes for both female workers and female partners of male workers” (National Institute for Occupational Safety and Health. Waste Anesthetic Gases: Occupational Hazards in Hospitals. 2007.Department of Health and Human Services, Centers for Disease Control and Prevention; Publication No. 2007-151). Really? Neither one of us, and we are pretty sure that none of you, have ever been tested/monitored for occupational exposure or related potential health issues to waste anesthetic gases.
SPA’s health and wellness special interest group, led by Norah Janosy and Rebecca Margolis and frequent contributors to the PAAD. have been begging SPA’s leadership to conduct a survey of our members looking at these very health issues. While survey results from the 1970s suggested potential health issues from chronic occupational exposure to volatile anesthetics (ether, halothane, enflurane) and nitrous, this data is very much out-of-date. A 2016 review was hindered by many studies with flawed methodology and concluded “very few consistent data exist”. This adds fuel to the fire that the time to do this is long past due.
Finally, some techniques that reduce occupational exposure to volatile anesthetics can be environmentally beneficial as well. I (DG) think the most valuable part of this article is the effort the authors make to highlight the overlapping benefits of low-flow anesthesia, closed filling systems for vaporizers and automated control (versus manual control) of end-tidal anesthetic gases to environmental and personal health.
Myron Yaster MD and Diane Gordon MD