CSA Online First

CSA Online First is a weekly blog featuring insights from CSA members themselves.

Edited by Rita Agarwal, MD, FAAP, with contributions from CSA’s Committee on Professional and Public Communications, Online First is a place where knowledge and opinion from any one of our 3200 plus physician-anesthesiologist members can be shared, discussed and deliberated to advance the specialty of anesthesiology, the practice of medicine and society in general.

"Better solutions to difficult problems are usually made when all sides are heard."

Steven Goldfien, MD


We Have the Ability to Reduce the Environmental Impact of our Anesthesia Techniques and Strive for Sustainability

  • Bohringer, Christian, MD
| Jun 04, 2019

Bohringer Before I begin this blog, I want to emphasize that patient safety will always need to take priority for anesthesiologists over any monetary or environmental considerations when we make decisions about how we practice medicine. 

As hospitals and other health care organizations seek ways to promote environmental sustainability and reduce adverse impact of their activities on the natural environment, we as anesthesiologist have the opportunity to not just contribute to these efforts but to lead them.

As anesthesiologists we have the ability and the obligation to seriously consider the environmental impact of our daily working activities on environmental sustainability. With our sights always focused on the safety of our patients, we should investigate the environmental cost of our actions and try to ameliorate their impact as much as possible. There are several ways in which we can achieve this.

Limiting greenhouse gas emission due to anesthesia:

The mitigation of climate change is arguably the most important issue that faces our generation. While anesthesia and health care activities are a less important contributor to greenhouse gas emissions than wildfires and the combustion of fossil fuels, they nevertheless have an important impact. In 2013 it was estimated that 10% of greenhouse gas emissions were related to the health care industry. (1) Anesthetic gases and vapors account for 5% of the carbon footprint for all National Health Service (NHS) organizations. (2) 

Desflurane is a much more potent greenhouse gas than sevoflurane (3) and the greenhouse gas effect of one hour of desflurane anesthesia is equivalent to driving in a modern car for 230 miles and of one hour of sevoflurane anesthesia for 30 miles respectively. (4) The greater greenhouse effect of desflurane results from its longer atmospheric lifetime (21.4 years) compared to that of sevoflurane (1.4 years). (5) Nitrous oxide is also a well-known greenhouse gas. (2) The largest amount of medical nitrous oxide emitted on this planet comes from the use of “Entonox” which is a mixture of 50% nitrous oxide with 50% oxygen that is used for labor analgesia in many countries outside the USA. (6) A significant reduction in world-wide medical nitrous oxide emission could therefore be achieved by increasing the use of epidural analgesia during labor or parturition in other countries to the same level as in the United States instead of relying on inhaled “Entonox”. 

It has been suggested that the use of desflurane and nitrous oxide should be restricted to cases where there is a significant patient benefit of these drugs in order to limit the greenhouse effect of anesthesia. (7)   

The environmental effects of desflurane, nitrous oxide and other volatile agents can be ameliorated by employing low fresh gas flow techniques with a circle breathing system. The CO2 absorbent “Amsorb” which consists of calcium hydroxide instead of the conventional sodium hydroxide allows low flow anesthesia with sevoflurane because there is minimal production of compound A with this absorbent. There is also no carbon monoxide production with it when using desflurane regardless of the hydration status of the carbon dioxide absorbent. (8)

Propofol infusions are associated with lower greenhouse gas emissions than volatile anesthetics but they create more medical waste in the form of syringes, syringe tubing, anti-reflux valves and additional intravenous catheters that are inserted to administer a total intravenous anesthetic. The electricity requirements for the pump delivery systems and the carbon footprint of the manufacture of the infusion pumps also need to be considered. (9)

Reducing medical equipment waste:

Another big area affecting the environmental footprint of our medical specialty is the use of airway equipment like endotracheal tubes (ETTs), laryngoscopes, bronchoscopes, and breathing circuits. Over time our specialty has moved from re-usable rubber ETTs to disposable polyvinyl chloride (PVC) ETTs, from re-usable laryngeal mask airways (LMAs) made from silicon to single use disposable LMAs made of PVC. This move towards single use disposable equipment was primarily driven by the risk of cross-contamination and the potential risk of nosocomial cross-infection. There continue to be outbreaks of pseudomonas, mycobacterium, hepatitis B and C from inadequately disinfected bronchoscopes and endoscopes. (10) These outbreaks are usually due to a breakdown in the cleaning and disinfection protocols for this equipment.

Currently, there is a move underway to replace re-usable laryngoscopes and bronchoscopes with single use disposable laryngoscopes and bronchoscopes. The glutaraldehyde that is used to disinfect scopes is a fluid that is toxic to the environment and may cause allergic reactions like eye irritation, headaches, and bronchospasm in health care workers and patients that are exposed to it. (11,12) While it would appear at first glance that re-useable equipment is more environmentally friendly than single use disposable equipment, the toxicity and disposal of the cleaning fluids and the energy expenditure of the sterilization process also need to be taken into account. The imaging quality of the re-usable scopes also deteriorates with each disinfection/sterilization episode and poor lighting with re-usable laryngoscopes and poor visualization with re-usable bronchoscopes can quickly lead to a patient-safety issue. Some single use equipment can be recycled, and some companies offer recycling programs. 

Breathing circuits are currently being re-used between different patients in many parts of Anesthesia equipmentthe world with the inclusion of a pleated hydrophobic membrane filter between the circuit and the patient. (13) This eliminates having to dispose of the breathing circuit after each patient and enables the use of higher quality breathing circuits that are less likely to have leaks than the disposable circuits. There are no reported outbreaks of nosocomial cross-infection when re-useable breathing circuits were used in combination with these filters. (14) Example of a pleated hydrophobic membrane filter that allows for breathing circuits to be re-used.

These filters also perform a heat-moisture exchange function while at the same time protecting the breathing circuit from contamination with viruses and bacteria. They can reduce waste and save money by allowing the same breathing circuit to be used for several patients. Before we dismiss this practice as dirty and unacceptable, we should remember that we do in fact not change the carbon dioxide absorbent in the circle system between every patient and we therefore are already reusing part of the breathing system without even protecting it with a viral filter. When anesthetizing a patient with tuberculosis or hepatis B however the breathing circuit should not be reused, and the carbon dioxide absorbent canister should also be discarded at the end of the case. Patient safety and eliminating the risk of nosocomial cross-infection will always need to take a higher priority in our activities than environmental concerns.

Spinal, epidural, and regional nerve blocks can also be used to reduce the environmental impact of anesthesia. With this type of anesthetic an ETT, LMA, oral airway, or breathing circuit is not necessary and there will be much less medical waste. A regional or spinal anesthetic is therefore not only good for the environment, but it also significantly reduces equipment costs. A fast goal-directed surgery is usually necessary to complete the surgery before the block wears off. Even if a general anesthetic is used a fast operation will still be more environmentally friendly than a slow one because less sevoflurane or propofol will be used. We should therefore nurture focused and goal-directed working habits in our surgical colleagues to reduce the environmental impact of operating room (OR) activities.

Pulse oximeters and blood pressure cuffs can be refurbished, and many institutions use clip-on probes that can be used for multiple patients. The reprocessing reduces the environmental impact of de novo manufacturing and provides considerable cost savings on disposal and purchasing. (15)

Reducing drug waste:

Large amounts of propofol get discarded into the environmental waste stream and this is toxic to biological systems. Propofol waste was significantly reduced when large propofol bottles were removed from the OR formulary and only 20 ml bottles were provided. (16)

Syringes that have been prefilled by the pharmaceutical manufacturer have become popular in anesthesia because they reduce drug waste due to the increased shelf-life when the drug is in the syringe. Prefilled syringes allow an unopened syringe to be used at a later time without having to worry about the possibility that bacterial contamination occurred during the process of drawing up the drug out of an ampoule. When an ampoule has been drawn up the drug in the syringe has a very limited shelf life. The propofol emulsion in particular supports bacterial growth and should be discarded after six hours due to the contamination risk. Prefilled syringes also eliminate drug labelling errors. 

Appropriately sized propofol ampoules should be selected for each anesthetic to prevent large amounts of drug having to be wasted at the end of the case. When prefilled syringes are not available the pharmacy can divide ampules into appropriately sized doses. This reduces drug waste in jurisdictions where drug splitting form multi-dose vials is no longer permissible. This strategy has been useful for drugs like ketamine and remifentanil. The contamination risk when the drugs are drawn up form large ampoules in the pharmacy is reduced because the pharmacy prepares these syringes under a laminar flow hood.

Reducing energy waste:

Excessive use of air-conditioning in hospitals needs to be avoided. At our institution, the preoperative holding area is very cold, and we keep patients warm with forced air heating blankets. It makes little sense to cool a room to a level that is uncomfortable or dangerous for the patients and then use electricity to keep them warm with forced air heating blankets. The ORs are also kept cold because in the past surgeons used to feel hot operating under incandescent lights. These days the light in ORs is generated by light emitting diodes (LEDs). LEDs emit much less heat than the incandescent lamps. It is therefore no longer necessary to keep ORs as cool as before. Most institutions however keep the OR temperature at historic levels because nobody is considering the reason for the original settings and nobody is re-thinking what an appropriate level should be with regard of the new technology that is currently employed. A lot of energy is getting wasted by excessively air-conditioning rooms and then needing forced air warming blankets to keep the patients warm. 

Ways to limit Anesthesia’s Environmental Impact: Table Summary

Use low fresh gas flow with calcium hydroxide CO2 absorbent (Amsorb)

Avoid desflurane or nitrous oxide unless medically indicated

Encourage speedy goal-directed surgery

Use spinal, epidural or regional anesthesia instead of general anesthesia

Use epidurals for labor analgesia rather than inhaled nitrous oxide (Entonox)

Use appropriately sized propofol bottles for each case

Use syringes prefilled by the manufacturer

Pharmacy splitting large ampoules into appropriate doses under a laminar flow hood

Consider using re-useable breathing circuits with viral filters

Use refurbished equipment like blood pressure cuffs and pulse oximeters

Use re-useable laryngoscopes or at least recycle single use laryngoscopes

Appropriately adjust temperature settings in pre-op areas, the OR and the recovery room


We therefore need to continuously re-evaluate our practices in line with the ever-changing technology in our workplace to ensure that we do not cause a bigger environmental impact than necessary. This will require an ongoing consideration of new techniques and how they affect the environmental cost of our activities. What is best practice today for the environment will almost certainly not be the best in the future.  As technology changes we need to adapt our techniques with sustainability in mind. Continuous and thorough reflection on this topic is necessary from now on to maintain the livability on this planet. This will demand some continuing mental effort on our part. Kermit the Frog from the Muppet Show was in fact correct when he stated that “It’s not easy being green”.

We do however have one great advantage in our favor. Limiting the environmental burden of our anesthetics usually also leads to significant cost savings from reducing the number of drugs and equipment that are being used – a top priority for today’s entire heath care system. Given this alignment of environmental stewardship with cost-saving strategies in health care, it should not be difficult to implement a “greener” anesthesia work environment. The old adage that “Money Talks” has definitely some truth to it. We can provide tangible, economic benefit to our hospital administrators and serve as best practice example to our peers in efforts to reduce our collective footprint on the environment. 


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