Conflict of Interests Dr. Vivian Ip is the Chair of the Environmental Sustainability Section, the Chair of the Regional Anesthesia Section at the Canadian Anesthesiologists’ Society, and the Chair of the Green Anesthesia Special Interests Group at the American Society of Regional Anesthesia and Pain Medicine.

Introduction Environmental Sustainability involves making responsible choices that ensure long-term health of our planet and supply of resources. It ultimately affects human health in numerous ways, especially those at the extremes of ages. The health effects of these disruption include increased respiratory¹ and cardiovascular disease,^{2 3} injuries, and premature deaths related to extreme weather events, changes in the prevalence and geographical distribution of food- and water-borne illnesses and other infectious disease, and threats to mental health.⁴ A record 2.2 million hectares was burnt across Alberta, Canada, displacing adjacent community and interrupting healthcare provision.⁵ About 60 wildfires (10 times more than average) that begin in the previous seasons and smoulder underground for months before reigniting in the spring once the snow melts, and the cycle continues.⁵

Climate change, has received increasing attention in recent years with the extremes of weather events, retreating glacier leading to rising sea-level threatens food and water supply, as well as altering natural ecosystems on which human depends, is now a climate crisis as action is urgently needed.⁶ The Lancet Climate Change Commission declared climate change as the greatest health threat of the 21^st Century.⁷ The World Health Organization is projecting an additional 250,000 deaths per year attributable to climate change in the coming decades.⁸ If global health care sector were a country, it would be the fifth largest greenhouse gas emitter on the planet.⁹Health care’s climate footprint is equivalent to 4.4% of global net emissions (2 gigatons of carbon dioxide equivalent), or equivalent to the annual greenhouse gas emissions from 514 coal-fired power plants.⁹ Until recently, there was limited awareness on the significant contribution the health care sector makes to the carbon footprint. The European Union as a political union is forging a collective political response to the climate crisis. It has set goals to drive action on a national level.⁹ Some regions in Europe, particularly in Scandinavia and the Netherlands, zero emissions hospital buildings, innovative climate-smart technologies, and strategies to address supply chain emissions.¹⁰ In the United Kingdom, the National Health Service is leading the environmental sustainability efforts in health care with over a decade of experience with sustainable practice in anesthesia. They have set targets to reach net zero by 2040 with an ambition to reach an 80% reduction by 2028 to 2032.¹¹ Across the Atlantic in Canada, it has committed to a 40-45% emission reduction by 2030 and to reach net zero emission by 2050. Given that carbon footprint of 1 hospital bed equals that of 5 households,¹² curbing carbon emissions in healthcare could play a major role. As with other industries, health care needs to adopt the ‘Triple Bottom Line’ which was fist described in the business model by John Elkington in 1990s where he suggests that competing corporate entities seek to main their relative position by addressing people and planet issues as well as profit maximization,¹³ namely, the 3 ‘Ps’: P eople, P lanet, P rofit. Therefore, rather than focusing on profit alone, social equity, wellbeing of people, as well as environmental sustainability and energy conservation are equally important.

This framework is applicable in regional anesthesia as it suggests that patient care has three domains and by maximizing patient safety and care does not necessarily result in financial and environmental trade-offs. Aligning all 3 ‘Ps’ helps the bottom line when considering the significant future costs than otherwise.

It is often assumed that regional anesthesia is more environmentally sustainable than alternatives. In fact, recent publication has shown the significant amount of carbon dioxide emission (an equivalent of 26, 900 lbs of coal burnt, or 2750 gallons of gasoline consumed) by increasing the amount of regional anesthesia performed for total knee arthroplasty.¹⁴ Contrastingly, the publication from Australia showed that regional anesthesia, general anesthesia and the combination of both, could be comparable depending on the specifics of institutional anesthesia practices.¹⁵ It is an observational study evaluating their different anesthesia practice for total knee arthroplasty. Upon examining the breakdown of the life cycle analysis, it is apparent that the specifics of their practice in general anesthesia is much more environmentally sustainable, with the use of sevoflurane, and reusable operating attire and equipment. On the other hand, their practice in regional anesthesia is less environmentally sustainable owing to the use of high flow oxygen, as the process of compressing oxygen into liquid oxygen for medical use is highly energy intensive. Furthermore, a large amount of procedure attire was used and towels for hand-drying, despite being reusable, contributed to substantial environmental impact in the regional anesthesia group. This highlights the need to reflect on clinical practice in regional anesthesia to balance infection control and environmental sustainability. As a result, a Delphi consensus study across multiple countries was conducted, to provide guidance on environmentally sustainable practice in regional anesthesia from experts within various subspecialties, including regional anesthesia, obstetrics anesthesia, intensive care, and infection prevention, reconciling infection control with resource stewardship. It was found that infection control practices which are rooted in evidence often do not interfere with sustainability and reach consensus, while less evidence-supported measures, only gained weak consensus.¹⁶ There were strong consensus that a sterile gown was unnecessary for either single injection of peripheral nerve blocks or spinal, and trending towards not required for catheter techniques.¹⁶ There was also strong consensus that minimal equipment should be included in the pre-made pack and the pre-existing packaging for equipment such as nerve block catheter, can be used as sterile work space.¹⁶ Only weak consensus was obtained in using small plastic adhesive cover for the ultrasound transducer for single injection peripheral nerve blocks and catheter-over-needle assembly with very short catheters.¹⁶ Another unexpected finding was a high degree of uncertainty amongst the experts regarding reusable versus disposable attires, despite existing life cycle analysis data appraising the environmental impact, demonstrating the need to raise awareness of such data, which is less familiar for most anesthetists.¹⁶

Electricity contributes significantly to the carbon footprint in healthcare,⁹ and opportunity to reduce this is by reflecting on how ultrasound machines are used in regional anesthesia. Recently, we performed a study on energy consumption used by a single ultrasound machine, comparing control group: standard practice of leaving ultrasound machine on during the day, against intervention: turning off the ultrasound machine when not in use. The primary outcome was energy consumption. Our unpublished data showed 87% reduction in energy consumption when accounting for the differences in duration of use between the groups. A total of 1.55kWh of energy saving per day was logged which equates to 161.2kg reduction in carbon dioxide emissions and almost 74 Euros yearly cost savings per ultrasound machine.¹⁷ Given the scale of ultrasound use in healthcare, even minor changes can contribute to a cumulative impact on an ever-increasing environmental impact from healthcare. This is a simple measure to contribute to a responsible resource stewardship.

Another area where regional anesthesia reduces carbon emission is the ambulatory program where patients can be discharged with a nerve block catheter infusion. In Canada, carbon footprint for 1 hospital bed is equivalent to that of 5 household, by discharging those patients who only required to stay as in-patient due to pain control can both reduce environmental impact and benefit patient in terms of better pain control with minimal opioid, if any. This also reduces the potential for improper opioid disposal and opioid diversion in the community.

The second ‘P’-profit is divided into short- and long-term, both favoring regional anesthesia, especially when used solely for surgical anesthesia. This approach negates the need for costly volatile agents, which are potent greenhouse gases. Regional anesthesia also reduces opioid use and the associated complications, and ambulatory regional anesthesia programs can lower the cost of hospital stay. Long-term cost savings are supported by large meta-analyses demonstrated a reduction in major complications post total joint arthroplasty in the neuraxial anesthesia group compared to the general anesthesia, with the former associated with lower odds or no difference in virtually all reported complications, except for urinary retention.¹⁸ Similar benefits are observed with peripheral nerve blocks, improving outcomes such as lower odds for cognitive dysfunction, respiratory failure, cardiac complications, surgical site infection, thromboembolism and blood transfusion.¹⁸ Fewer complications reduce both costs and the environmental impact on the healthcare system, creating a positive cycle by reducing associated morbidities and mortalities.

With the last ‘P’ being people, encompasses social equity, well-being and patient safety. Prioritizing patient care while reducing environmental footprint can optimize costs by accounting for future expense of not addressing environmental impact on healthcare. Numerous studies highlight the benefits and safety of regional anesthesia. Increasing patient access to the regional anesthetics requires educating more anesthetists on basic blocks (Plan A).²⁰ Increasing the complexity of regional anesthesia only widens the gap between the generalists and regional anesthesia experts, diminishing access for patients to regional anesthesia. To enhance patient equity, regional anesthesia techniques should balance technical complexity with analgesia benefits, improving operating room efficiency, postoperative recovery and length of stay. Furthermore, public education is crucial to align their perceptions of regional anesthesia aligns with those of the physicians, ensuring informed choices regarding benefits of regional anesthesia techniques, while being realistic about complications.²¹

Implementing changes can be challenging, especially in a complex system such as healthcare. The norms, values, and the basic assumptions i.e. Culture of a given organization are constructed by interactions of individuals and groups within that organization, each with their own beliefs, values and skills.²² Measuring culture and initiating changes in complex organization with the unpredictable nature of healthcare is challenging. Recognizing the complex dynamic interactions of different perspectives, individual’s experiences and values, components, and politics of healthcare is essential to promote sustained and ever-improving changes.²²

In conclusion, regional anesthesia can reduce carbon emission, but only if the specifics to the practice is with environmental sustainability and resource stewardship in mind. Climate change is now a climate crisis and with cumulative action aligning with the triple bottom line from all within the healthcare system, positive impact in carbon reduction can be possible before the environmental impact becomes irreversible.

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