Environmental sustainability in veterinary anaesthesia

Veterinary Anaesthesia and Analgesia 2019, 46, 409e420

https://doi.org/10.1016/j.vaa.2018.12.008

PERSPECTIVE

Environmental sustainability in veterinary anaesthesia Ronald S Jonesa,1 & Eleanor Westb,1 a

School of Veterinary Science, University of Liverpool, Neston, UK

b

Davies Veterinary Specialists, Manor Farm Business Park, Higham Gobion, Hertfordshire, UK

Correspondence: Eleanor West, Davies Veterinary Specialists, Manor Farm Business Park, Higham Gobion, Hertfordshire SG5 3HR, UK. E-mail: [email protected] 1

Co-first authors.

Abstract

Introduction

Objective Attention is drawn to the potential of global warming to influence the health and wellbeing of the human race. There is increasing public and governmental pressure on healthcare organisations to mitigate and adapt to the climate changes that are occurring. The science of anaesthetic agents such as nitrous oxide and the halogenated anaesthetic agents such as greenhouse gases and ozone-depleting agents is discussed and quantified. Additional environmental impacts of healthcare systems are explored. The role of noninhalational anaesthetic pharmaceuticals is discussed, including the environmental life-cycle analyses of their manufacture, transport, disposal and use. The significant role of anaesthetists in recycling and waste management, resource use (particularly plastics, water and energy) and engagement in sustainability are discussed. Finally, future directions for sustainability in veterinary anaesthesia are proposed.

In 2010, climate change was called ‘potentially the biggest global health threat of the 21st century’ by The Lancet (Costello et al. 2009). Awareness of the impacts of human activity on the planet is gathering momentum, particularly given the increase in average temperatures since the 1960s (Intergovernmental Panel on Climate Change 2007). In the year 2000 alone, climate change was estimated to be responsible for the loss of 5.5 million disability-adjusted life years (CampbellLendrum et al. 2003). The healthcare effects of climate change are likely to disproportionately affect those who have least access to the world’s resources and those who have contributed least to its cause (Costello et al. 2009). In 2015, at the Paris International Climate Conference, 195 countries made legal commitments to take action in limiting global warming to less than 2
C above preindustrial average temperatures, to which end the European Union has stated targets of 40% reduction (from 1990 levels) in carbon emissions by 2030 (European Commission 2015). Even these targets may prove insufficient to prevent significant climate change (Steffen et al. 2018), and the Intergovernmental Panel on Climate Change has subsequently recommended limiting global warming to 1.5
C to reduce challenging impacts on ecosystems, human health and wellbeing (Intergovernmental Panel on Climate Change 2018). The medical profession is facing policy and healthcare pressures which have forced engagement with environmental issues (McCoy & Hoskins 2014; Weiss et al. 2016). Healthcare systems must develop strategies to mitigate (avoid the unmanageable) and adapt (manage the unavoidable) to environmental pressures. In this article, we discuss the environmental issues which affect veterinary anaesthetists and

Conclusions Veterinary anaesthetists have a considerable opportunity to drive sustainability within their organisations through modification of their practice, research and education. The principles of sustainability may help veterinary anaesthetists to mitigate and adapt to our environmental crisis. Due to their particular impact as greenhouse gases, anaesthetic agents should be used conservatively with the lowest safe fresh gas flow possible. Technologies for reprocessing anaesthetic agents are described. Keywords anaesthetic agents, climate change, environment, greenhouse gases, sustainability.

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suggest how we can promote resilience within the industry in the face of ecological changes. For this article, the relevant literature was identified using the terms ‘sustainability’, ‘climate change’ and ‘anaesthesia’ entered into the databases Scopus and Google in July 2018. The reference lists of retrieved papers were examined to identify further studies and sources for inclusion. There were no exclusion criteria. Why sustainability? As early as 1975, it was suggested that halogenated anaesthetic agents had the potential to harm the global environment (Fox et al. 1975) and whilst this particular impact remains a concern, our interest must extend beyond the discussion surrounding anaesthetic agents. Broader assessments of the impacts of healthcare systems make for startling reading; in 2013, the United States of America (USA) healthcare sector was estimated to be responsible for 12% of acid rain, 10% of smog formation, 9% of air pollutants and 1e2% of air toxins nationally (Eckelman & Sherman 2016). Ecological concerns include carbon emissions, ozone depletion, biopersistence, respiratory toxicosis, carcinogens, water acidification, eutrophication (excess nutrients leading to algae blooms) and aquatic ecotoxicity. Sustainable development has been defined by the Brundtland Commission as ‘development that meets the needs of the present without compromising the ability of future generations to meet their own needs’ (United Nations 1987). Furthermore, three pillars of sustainability were stated by the United Nations (UN): 1) environmental protection; 2) economic growth; and 3) social progress (United Nations 2002), also known as the triple bottom line of ‘planet, profit and people’. Introducing sustainability into veterinary anaesthesia will require a paradigm shift in approach; sustainability implies a lean and resilient working ethos which prioritizes preventative and holistic solutions and is likely to produce environmental, financial and health cobenefits. It will require action in multiple areas, including pharmaceuticals, waste and resource management, procurement, travel and leadership. As an interface between multiple clinical areas, veterinary anaesthetists are ideally placed to have an impact on institutional sustainability. In this article, we suggest opportunities to champion sustainable practices within veterinary organizations. 410

Anaesthetic agents as greenhouse gases Whilst the effects of anaesthetic gases on atmosphere have been comprehensively reviewed in detail (Campbell & Pierce 2015), they are summarized here to highlight the areas of concern. Solar energy is essential for life on Earth. After being absorbed by the Earth’s surface, solar energy is reemitted as infrared thermal radiation. Greenhouse gases and vapours (GHGs) are compounds that have a significant atmospheric lifetime and possess infrared absorption bands that overlap with the outgoing radiation from the Earth’s lower atmosphere (Andersen et al. 2012). GHGs have the capacity to absorb and reflect solar radiation back to the Earth’s surface. Whilst GHGs serve to maintain a more stable surface temperature through night and day, higher concentrations will correspondingly maintain a higher surface temperature. A marked and rapid increase in the atmospheric carbon dioxide concentrations has occurred since around the industrial era in the 1800s (Brook & Buizert 2018). The Intergovernmental Panel on Climate Change (IPCC) concluded that ‘most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations’ (Intergovernmental Panel on Climate Change 2007). The problems associated with temperature rises include increasing disease burden from heat waves, droughts, malnutrition, diarrhoea, cardiorespiratory and infectious diseases, flooding of coastal areas but decreased water availability elsewhere, and loss of ecosystems including habitats and species (Costello et al. 2009). The GHGs include carbon dioxide, methane, nitrous oxide, water and all of the halogenated anaesthetic agents in common use (Campbell & Pierce 2015). Since multiple GHGs exist, it is their combined effect that matters; this is evaluated using carbon dioxide equivalents (CO2e, kg). It has been estimated that the annual global climatic impact of anaesthetic agents released into the atmosphere is 4.4 million tonnes of CO2e, which is roughly equivalent to one coal-powered station or 1 million passenger cars (Andersen et al. 2010). By comparison, the global emissions of GHGs are estimated as 49 gigatonnes CO2e per year, of which 24% originate from agriculture and other land use and 14% from the transport sector (Intergovernmental Panel on Climate Change 2014), whilst only around 2.1%

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Sustainable veterinary anaesthesia RS Jones and E West

originate from healthcare in developed countries (Wyssusek et al. 2019). Anaesthetic gases contribute around 5% of the total carbon emissions of the acute healthcare facilities within the National Health Service (NHS) for England; to compare, the gas used to heat NHS England’s buildings and water produces 11% of the total carbon emissions (Sustainable Development Unit 2013). Although anaesthetic gases contribute a relatively low amount to global carbon emissions, and are present at vastly lower concentrations than carbon dioxide, they are disproportionately effective as GHGs since they absorb infrared radiation at around 10 mm. This overlaps with an infrared spectral range or atmospheric window of approximately 8e14 mm where absorption of radiation by any naturally occurring GHG is relatively minor (Andersen et al. 2012). This atmospheric window is an important mechanism by which the Earth can cool itself. The importance of each GHG in driving climate change can be quantified using radiative forcing (W me2), which is a measure of the influence that a factor has in altering the balance of incoming and outgoing energy between the Earth and its atmosphere (Intergovernmental Panel on Climate Change 2007). Positive radiative forcing tends to increase the Earth’s surface temperature. The anaesthetic agents are thought to be responsible for 10e15% of total anthropogenic radiative forcing of the climate since preindustrial era (Andersen et al. 2012). Various metrics are used to measure the atmospheric impact of various agents (Table 1). To allow real-time calculation of CO2e during anaesthesia,

online spreadsheets or smartphone apps are available (Pierce 2015; Yale University 2016) and can be used to highlight the effects of different practices. The total greenhouse emissions (CO2e, kg) caused directly and indirectly by a person, organization, event or product can be referred to as its carbon footprint (Campbell & Pierce 2015). The carbon footprint of anaesthetic gases can be calculated by multiplying the total mass released into the atmosphere by the global warming potential over 100 years (GWP100) (Andersen et al. 2012). The GWP100 is a measure of a GHG’s ability to trap heat and can be compared with the GWP100 of carbon dioxide, which is one. GWP100 is calculated based on a compound’s persistence in the atmosphere (or atmospheric lifetime) and how efficiently it reflects solar radiation back to the Earth. Table 1 highlights the particularly high carbon footprints that result from using nitrous oxide and desflurane due to the relatively low potencies of these agents and therefore larger quantities released, longer atmospheric persistence, and in the case of desflurane, a higher radiative forcing effect (Sherman et al. 2012). An additional effect of nitrous oxide, and to a far lesser extent halothane and isoflurane, is the destruction of ozone molecules which limit the transmission of harmful ultraviolet light towards the Earth’s surface (Logan & Farmer 1989). Nitrous oxide has been described as ‘the single most important ozone-depleting emission… throughout the 21st century’ (Ravishankara et al. 2009). The global Montreal Protocol to protect the ozone layer was amended in 2016 to control hydrofluorocarbons but not anaesthetic agents (United Nations 2017); this situation

Table 1 The atmospheric characteristics of anaesthetic gases and vapours Atmospheric characteristics

Nitrous oxide

Desflurane

Isoflurane

Sevoflurane

Carbon dioxide

Atmospheric lifetime (years)* Radiative efficiency (W me2 ppbe1)y Global warming potential over 100 years* Carbon dioxide equivalent (CO2e, kg) per MAC-hour for canine anaesthesiaz at 1 L minutee1 oxygenx Equivalent to car driving (miles) per MAChour of canine anaesthesia at 1 L minutee1 oxygen**

110 0.003 310 36¶

14 0.469 2540 89

3.2 0.453 510 3

1.1 0.351 130 1

74 0.676 1

140¶

348

12

4

MAC, minimum alveolar concentration. * Campbell & Pierce 2015. y Andersen et al. 2010. z Steffey et al. 2017. x Pierce 2015. ¶ Assuming nitrous oxide and oxygen combined at 1 L minute1 each to vaporize sevoflurane. ** Assuming United Kingdom average car emissions of 160 gCO2 kme1 (256 gCO2 milee1).

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may change as the climate crisis develops and the effect of anaesthetic agents becomes proportionately more significant. Whilst medical emissions of atmospheric nitrous oxide are by no means the most significant (they account for less than 4% of all nitrous oxide emissions, with the majority of emissions originating from microbial action on nitrogenous fertilizers) (Campbell & Pierce 2015), its environmental harm and atmospheric persistence weighs against its therapeutic benefit in veterinary anaesthesia. Xenon is a modern anaesthetic agent which is produced by fractional distillation of air as a byproduct of oxygen production. As an inert gas, xenon does not contribute to GHG or ozone depletion; however, 220 watt hours of energy is used to produce 1 L of xenon (Gadani & Vyas 2011), which is a similar energy demand per litre to using a desktop computer for 1 hour. Its future use as a clinical anaesthetic agent is only viable if stringent recycling technologies are employed. Minimizing inhalational anaesthetic use It is clear that we should aim to minimize our use of anaesthetic gases and vapours and discuss eliminating the use of nitrous oxide and desflurane in clinical veterinary anaesthesia altogether. Reductions in anaesthetic gases may be achieved by various means. The simplest methods include using, where appropriate, rebreathing systems and the lowest safe fresh gas flow (FGF). Using low flow (0.5e1 L minutee1), minimal flow (0.25e0.5 L minutee1) or closed circuit techniques (<0.25 L minutee1; or flow equal to metabolic oxygen consumption plus system gas leaks) will reduce expense and waste of anaesthetic gases as well as maintain heat and moisture within the breathing system (Brattwall et al. 2012). However, these FGF may be impractical in all clinics due to the increased risk of delivery of a hypoxic mixture due to inadequate denitrogenation, or accumulation of other gases including endogenous compounds (such as methane, water vapour and argon) and exogenous toxins (such as carbon monoxide) (Gregorini 1992). Monitoring the inspired oxygen concentration is critical to avoiding hypoxic mixtures when using low FGF (Feldman 2012). Strategies to avoid toxic gas accumulations during low FGF anaesthesia include using absorbents without strong alkalis, avoiding dessication of absorbents and flushing intermittently with high FGF every 30 minutes during anaesthesia 412

(Feldman 2012). At lower FGF, there is also a risk of an inadequate anaesthetic gas concentration due to dilution or failure to appreciate the slow rate of change of anaesthetic concentration; monitoring end-tidal anaesthetic concentrations will mitigate this risk (Brattwall et al. 2012). These techniques additionally require vaporizers and flowmeters which can perform accurately at lower flows. The effect of increased use of CO2 absorbents at low flows on carbon footprint has not been established. Changing to a practice of turning off FGF rather than the vaporizer will limit agent wastage during such procedures as moving or positioning the patient, or endotracheal intubation following induction of anaesthesia using a mask or chamber system to deliver the anaesthetic agent. Newer anaesthetic machines incorporate automated electronic closed-loop technologies to accurately control end-tidal agent concentrations; conflicting results suggest 15% increases (Wetz et al. 2017) or 32% and 44% reductions in agent con€ sumption (Ozelsel et al. 2015) and GHG emissions (Tay et al. 2013), respectively, the variation being mainly due to the difference in initial FGF over the first 15 minutes of anaesthesia used by the electronic algorithms to achieve desired inspired oxygen concentrations. Of interest, Tay et al. (2013) found no increase in the cost of CO2 absorbents, although larger (and therefore more efficient) canisters were used in the electronic closed-loop group where lower flows were used. Further investigation of the cost of increased CO2 absorbance is required. Use of charcoal and zeolite reflection filters can conserve anaesthetic agents (Sturesson et al. 2015). Using this principle, an anaesthetic conserving device (AnaConDa; Sedana Medical, Sweden) containing a charcoal filter placed between the endotracheal tube and the breathing system adsorbs and then releases anaesthetic agents. Agent consumption was similar to a circle breathing system at <1.5 L minutee1 FGF, but could reduce agent consumption by 40e75% at higher FGF (<6 L minutee1) (Enlund et al. 2001; Tempia et al. 2003). These are currently used for sedation in medical intensive care units (Kim et al. 2017). Digitally controlled in-line reflectors are under investigation, which may improve precision in delivery of anaesthetic agents and reduce agent consumption by 55% at FGF of 1 L minutee1 (Mashari et al. 2018). Any such systems have the potential to increase patient dead space and potentially retain other gases such as carbon dioxide (Sturesson et al. 2015).

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Sustainable veterinary anaesthesia RS Jones and E West

Most countries have stringent controls on occupational exposure to anaesthetic vapours and gases, which will limit waste gases within the anaesthetic rooms. However, the majority of anaesthetic gases are vented into the atmosphere after use via reservoir and scavenging systems. The only real effective means of reducing anaesthetic agents in the atmosphere is to either capture and recycle them or to render them chemically inert. In Canada, a commercially available silica zeolite canister (Deltasorb Canister; Blue-Zone Technologies, Canada) can be attached to the scavenging reservoir and has been shown to completely remove isoflurane from exhaled gases (Doyle et al. 2002) which is then returned to the company for extraction and reprocessing of the anaesthetic agents into a new product. A new local recapture system (Anesthetic Recapture System; Anesthetic Gas Reclamation, Inc., Texas, USA) is also available and claims collection with reuse of 99% anaesthetic agent within the hospital. Full analyses of the carbon footprint produced by these systems have not yet been performed. Whilst none of the previously described techniques can be applied to nitrous oxide, mobile units are commercially available to catalytically convert it to oxygen and nitrogen (Excidio; Linde Group, Sweden). This type of technology can result in a six-to 17-fold reduction in CO2e (depending on energy source) (Ek & Tjus 2008) and can also be used to collect halogenated anaesthetic agents (Anesclean; Showa Denko K.K., Japan) (Yamauchi et al. 2010). Widespread use of such technology could revolutionize anaesthetic agent procurement and emissions, particularly in larger hospitals. Injectable anaesthetic and analgesic drugs It is, of course, not just the inhalational agents used in anaesthesia which can have an environmental impact, but all of the pharmaceuticals used including ancillary agents such as cleaning products. The use of total intravenous anaesthesia may eliminate the GHG effect of volatile anaesthetic agents; however, there is an environmental cost as a result of their manufacture, transport, disposal and electricity consumption for their delivery. For instance, the carbon footprint of propofol use primarily stems from the energy required to operate the syringe pump (Sherman et al. 2012). In addition, when calculating the impact of intravenous morphine preparations, the final stages (particularly sterilization and packaging) contributed

to almost 90% of morphine’s carbon footprint (McAlister et al. 2016). Incidentally, the same is not true of halogenated anaesthetic agents; the downstream CO2e of waste emissions of sevoflurane and isoflurane are eight and 33 times greater, respectively, than the GHG emissions, relating to manufacture, procurement and disposal of the agent (Sherman et al. 2012). Wastage may increase the actual carbon emissions for injectable drugs; for instance, in two studies, it was shown that 32e51% of propofol in medical hospitals is wasted (Gillerman & Browning 2000; Mankes 2012). Altered prescribing practices may, therefore, have significant carbon impacts; for example, prescribing only for the immediate need and replacing, if clinically appropriate, parenteral drugs such as non-steroidal anti-inflammatory drugs (due to the high energy costs of sterilization) with perioperative enteral drugs. There is a drive for standardization of calculating the total carbon footprint of pharmaceuticals and medical devices (Sustainable Development Unit 2012), otherwise known as ‘cradle-to-grave’ or lifecycle analysis (LCA). For instance, using LCA, utilizing propofol to perform general anaesthesia creates nearly four times lower carbon emissions than desflurane or nitrous oxide (Sherman et al. 2012). If LCA became mandatory for equipment and pharmaceuticals manufacturers, comparisons between carbon emissions of particular anaesthetic techniques could be made. The comparison of inhalational anaesthesia versus additional regional nerve blocks in veterinary anaesthesia remains to be determined. However, when LCA of medical hysterectomies was compared, the anaesthetic gases accounted for about 70% of the total surgical and anaesthetic carbon footprint (Thiel et al. 2015), suggesting a potential role for intravenous and regional anaesthesia. Further research using the LCA approach is needed to holistically evaluate the benefit of alternative approaches to inhalational anaesthesia. Resource consumption and waste management Many easy sustainability goals can be met by simple changes to resource use and waste management, similar to changes which might be made in a domestic setting. High-priority resources to conserve include electricity, gas, oil, water and paper. Simple changes in the anaesthesia department are described in several review articles and might include turning off electronic equipment such as active anaesthetic

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scavenging systems, air conditioning or forced warm air machines when not in use, using alcohol-based scrubs or intermittent water flow devices for hand asepsis to reduce water consumption, redesigning sterile procedure kits to reduce wastage, and installing rechargeable batteries in portable equipment (Kagoma et al. 2012; Sherman & McGain 2016; Axelrod et al. 2017; Wyssusek et al. 2019). New technologies such as low-flow scavenging interfaces (Dynamic Gas Scavenging System; Anesthetic Gas Reclamation, Inc.) may also provide significant energy savings (Barwise et al. 2011). In general, the more hazardous or infectious the waste, the more expensive and polluting are the disposal methods. The waste hierarchy (Fig. 1) is a useful concept introduced in 1975 by the EU in order to optimize waste management. A legal duty of care was placed on business and public bodies to prevent waste and waste residue disposal where possible by moving up the waste hierarchy ladder. Following the waste hierarchy, by improving waste segregation, is likely to provide significant financial savings; clinical waste streams can have disposal costs 10 times those of recycling waste streams. Systematic application of these principles in the medical environment is reported using the five Rs of waste management: reducing, reusing, recycling, rethinking and researching (Kagoma et al. 2012). The priority is to avoid initial use of resources where possible, and this is best achieved by the audit of current practices within organizations. Around 60% of the carbon footprint of a hospital is likely to result from procurement of materials and equipment (Sustainable Development Unit 2015); therefore, incorporating sustainability into procurement planning is essential and suggestions to achieve this in the

veterinary clinic are outlined in Table 2. In medical anaesthesia, there is great pressure to avoid reuse of medical devices such as anaesthetic breathing systems, face-masks, laryngoscopes and catheters to facilitate infection control (Association of Anaesthetists of Great Britain & Ireland 2008). Development of greater understanding regarding the risks of infection, methods of decontamination, new methods of recycling of contaminated single-use equipment and full LCAs for medical devices (including costs of sterilization) will inform these decisions to reduce the dilemma. Given that new electricity in the UK/EU is principally sourced from renewable sources rather than fossil fuels, converting to reusable rather than single-use equipment in a five-theatre medical hospital was estimated to result in 84% reduction in CO2 emissions and an annual saving of around £18,000, although water use was doubled (McGain et al. 2017). Reusable surgical textiles can offer significant improvements in carbon emissions and resource usage (Overcash 2012) and may improve infection control (Markel et al. 2017). However, world water shortages are predicted which may adjust the balance of calculations in the future (Mancosu et al. 2015). Plastic waste disposal is a topical issue in many countries. Plastic manufacture and disposal are energy-demanding processes, and incineration of medical plastics is a leading cause of harmful toxic emissions such as dioxins (Windfeld & Brooks 2015). Over 40% of disposable medical devices are made of polyvinyl chloride (PVC), which is cheap and durable. However, health concerns regarding high dioxin emissions and the phthalate plasticisers such as diethylhexyl phthalate (DEHP) used to soften PVC (Windfeld & Brooks 2015; Benjamin et al. 2017)

Figure 1 The Waste Hierarchy (adapted from Department for Environment, Food and Rural Affairs 2011) 414

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Sustainable veterinary anaesthesia RS Jones and E West

Table 2 Example of a sustainable procurement policy Area

Examples and resources

Evidence from suppliers of environmental Accreditation standards include:  ISO 14001 (International Organization for Standardization: Environmental Management) policies or accreditations    

EMAS (European Union Eco-management and Audit Scheme) The Carbon Trust Investors in the Environment (UK only) Green Guide for Healthcare (self-certifying)

Environmental legislation and Environmental management schemes; environmental policies; waste certificates; compliance, management and impacts duty-of-care visits; carbon life-cycle impacts; supporting local businesses; zero-tolandfill policies Energy Sourcing renewable energy; divesting from fossil fuels Packaging Requesting recyclable, reusable, biodegradable and minimal packaging Transport costs Reducing number and distance of journeys; consolidating deliveries; teleconferencing Product choice Avoidance of environmentally toxic products; energy efficient equipment; healthier and sustainable foods Stock control Stock so that supply is sufficient but items do not go out-of-date; reuse or recycle before reordering Ethical procurement Knowledge of supply chain to protect labour standards; source Fair Trade products; follow ethical procurement guidelines (British Medical Association, 2017) Water management Employ water-saving devices; avoid bottled water; ‘grey’ water facilities; droughtresistant planting

have resulted in many manufacturers producing PVC-free and DEHP-free products (Conway 2017). Disposal of pharmaceutical agents is strictly controlled in most countries, and drug-contaminated waste is often disposed by expensive incineration. Without incineration, volatile anaesthetic agents absorbed into charcoal canisters could be released into the atmosphere. However, drug contamination of water and soil is a recognized problem as many drugs are only partially removed by waste water treatment (Fatta-Kassinos et al. 2011). This may be problematic for drugs which, like propofol, persist and are toxic in the aquatic environment (Mankes 2012); however, the environmental risk of propofol has been categorized as low (Stockholm County Council 2019). In the UK, body fluids containing drug residues and metabolites by patients receiving therapeutic pharmaceuticals do not normally class as medical waste unless cytotoxic or cytostatic drugs are used and potentially dangerous quantities of unmetabolized drugs are likely to be present in the waste (Department of Health 2013). Most countries require an environmental risk assessment to be performed by the manufacturer during drug licensing. No unifying toxicity index exists, but there is guidance produced by the European Medicines Agency, under current review, on investigation and labelling of the environmental risk of medicinal products which includes indexing based on persistence, bioaccumulation and

toxicity of drugs (European Medicines Agency 2016), in addition to an existing index produced in Sweden (Stockholm County Council 2019). These indices should be considered when considering the ecological risk of drugs which may escape safe disposal methods. In the USA, around one-third of the waste generated in hospitals originates in the operating room (Chung & Meltzer 2009), and it is estimated that 40e58% of medical anaesthetic waste can be recycled (McGain et al. 2009; Shelton et al. 2012). Recycling options for many single-use items have historically been limited, with most waste deemed infectious or drug-contaminated and disposed of according to the legal requirement of the country, usually by alternative treatment (disinfection) or incineration, respectively. Recently, the UK’s Environmental Agency has granted a permit for contaminated medical-grade PVC to be recycled into tree ties. Using recycled PVC reduces the energy for production by 85%, and this scheme has been adopted in Australia and the UK (Vorster 2015). Unfortunately, this scheme is not currently available to UK veterinary producers due to the limitations of the environmental permit. Such new recycling and refuse-derived energy industries are developing to support a circular economy, redefining products and services to design waste out, and these are likely to be cost-saving for organizations (Goldberg et al. 1996). Additional innovations will

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reduce the need for incineration of plastic containers such as reusable sharps containers (Sharpsmart Reusable Container System; Sharpsmart, UK; Stericycle Bio Systems; Stericycle, UK) and cardboard pharmaceuticals waste containers (Bio-bin; Econix Ltd, UK; Clinisafe Cardboard Cartons; Frontier Medical Group, UK; 4GSafe Boxes; Icomed Ltd, UK). It is essential that each organization has a strategy to ensure that waste and waste residues generated are removed from incineration or landfill streams. Waste can be segregated at source into reuse, recycling, autoclave sterilization or refuse-derived energy streams, within national legal frameworks. Many waste companies offer ‘zero-to-landfill’ schemes. To assist in identifying the most sustainable options for each type of waste, a scientific summary of the environmental impact of various non-medical waste management options has been produced by the UK government (Department for Environment, Food and Rural Affairs 2011). One pragmatic problem is how to categorize medical waste to optimize financial and environmental costs (Windfeld & Brooks 2015); is the waste contaminated with noninfectious or infectious and pathogenic bodily secretions? Guidance is likely to be available from national regulatory organizations and must be communicated clearly to staff. Engagement in sustainability Many organizations now have environmental management schemes and corporate social responsibility (CSR) programmes, which aim to increase the positive impacts and reduce the negative impacts, relating to company activities. CSR policies usually include procurement, travel and transport plans, and community and staff engagement. Careful thought must be given to overcoming potential barriers to change, which can include social attitudes and logistic, institutional and legal restrictions (Hutchins & White 2009). The sustainability movement in medicine has made great progress in the past decade. Alone, the NHS’s activities contribute 3% of the UK’s national carbon emissions, but it has committed to an 80% reduction carbon emissions from the health and care systems by 2050 (Sustainable Development Unit 2009). There are various global medical healthcare initiatives which are driving sustainability via leadership, policy statements, research funding and education; a nonexhaustive list includes Healthcare Without Harm, the NHS’s Sustainable Development Unit, the UK Health Alliance on Climate Change and the Centre for Sustainable Healthcare. In addition, 416

there are environmental groups within the Royal College of Anaesthetists, the American Veterinary Medical Association, the Societe Francaise d’Anesthesie et de Reanimation, The Australian and New Zealand College of Anaesthetists and Association of Anaesthetists. The latter has produced a newsletter which gives an engaging summary of activities of UK medical anaesthetists, including research awards, ‘greening’ the headquarters and promoting sustainable conferencing with no conference bags, careful choice of location and venues, teleconferencing and meat-free days (Association of Anaesthetists of Great Britain & Ireland 2018). Future directions for sustainable veterinary anaesthesia Currently, there is little cohesive focus within the veterinary professions to direct sustainability initiatives. A clinical checklist has been produced by the American Society of Anesthesiologists (Axelrod et al. 2017) which can be used to guide sustainable anaesthetic practices within institutions (reproduced in modified format in Table 3). More resources are becoming available, such as the UK’s National Institute for Health Research framework to minimize waste by improving research design (National Institute for Health Research, 2010), and metrics to identify health benefit per tonne CO2e may become a standard part of research reporting. Engagement with the research community to promote sustainability principles in research anaesthesia is encouraged. Lastly, environmental awareness is slowly being introduced into medical and veterinary curriculums, often under the cover of the more collaborative One Health initiative (Nielsen & Eyre 2017; Walpole et al. 2017; Waters 2017). Suggested medical learning objectives for sustainability are 1) to be able to describe the interactions between the environment and human health, 2) to demonstrate the ability to improve sustainability in health care and 3) to address the wider ethical and legal dimensions of sustainability relating to geographically divergent and future populations (Walpole et al. 2015). At present, Elsevier prints Veterinary Anaesthesia and Analgesia in the USA on sustainably sourced paper (as certified by the Publishers’ Database for Responsible Environmental Paper Sourcing) and delivers copies worldwide in recyclable plastic wrapping (De Koning, personal communication 2018). However, Veterinary Anaesthesia and Analgesia is also available online with an ever-extending range of

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Sustainable veterinary anaesthesia RS Jones and E West Table 3 An anaesthesia sustainability checklist* Reduce volatile anaesthetic atmospheric waste

Reduce pharmaceutical waste

Reduce equipment waste

Waste segregation

Textiles Electronics Leadership

Low fresh gas flows Monitoring of inspired oxygen and end-tidal anaesthetic agent concentrations Avoid high-impact agents (desflurane, nitrous oxide) Consider intravenous and regional techniques Invest in waste anaesthetic recycling or destruction Use prefilled syringes or pre-packed kits Use appropriate sized vials Dispose of pharmaceuticals appropriately Replace perioperative injectable with oral medications Only open equipment intended for immediate use Purchase reusable or reprocessed equipment Adjust stock levels to minimize discard beyond expiry dates; eliminate unnecessary items Evaluate waste handling to move up the waste hierarchy Segregate waste strictly, according to legal frameworks Recycle where possible, in clinical and nonclinical streams Use reusable or nonplastic waste containers Minimize packaging Use reusable textiles Use towels and blankets efficiently Do not use unless proven benefit Use certified recycling site for disposal Develop a sustainability plan and committee, with advocates at local level Procure sustainably where possible Promote staff engagement with sustainability Evaluate travel within your organization Promote research into sustainability

* Based on ‘Appendix B: Anesthesiology Sustainability Checklist’ (Axelrod et al. 2017). A copy of the full text can be obtained from the American Society of Anesthesiologists or online at www.asahq.org/~/media/sites/asahq/files/public/resources/asa%20committees/greening-the-or.pdf?la¼en Last accessed 7 March 2019.

online content. Globally, information and communication technology produces an estimated 1.4% of total global carbon emissions (Malmodin & Lunden 2018). Whether there is an environmental advantage of reading a journal article online will depend on the lifetime of the device used, energy efficiency of the device, reading time and number of readers; one study estimated casual reading of academic articles on electronic devices to be more environmentally friendly than reading paper copies (Song et al. 2016). It is clear that there will be a growing need for carbon and climate literacy in both the veterinary clinical and research fields. It remains for veterinary anaesthetists, both as professionals and individuals, to decide how we will integrate sustainable practices into veterinary anaesthesia. In the future, it seems likely that carbon reduction commitments and sustainability plans will be required from all businesses and public bodies, and creation of these environmental management systems will make organizations more resilient. Understanding the greenhouse gas effects of inhalational agents can proceed along

with further development of low flow anaesthesia and consensus on the use of nitrous oxide and desflurane in clinical practice. Inclusion of sustainability topics into undergraduate and specialist curriculums may promote further research into life-cycle analyses of anaesthetic equipment and procedures and eventually better understanding of the environmental cost of veterinary healthcare across clinical and research fields. Educational conferences can be planned to reduce both the carbon footprint and environmental impact. We encourage veterinary anaesthetists to engage with sustainability and provide leadership within their own spheres. Authors’ contributions RSJ and EW: conception, preparing and revising of manuscript. Conflict of interest statement Authors declare no conflict of interest.

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