Anesthetic Gases Research Articles

Certified Registered Nurse Anesthetists’ occupational exposure to inhalational anesthetic agents: a survey of anesthetic gas safety

BackgroundAnesthetic gases have been known to cause damage when inhaled over long periods of time. Modern safety measures have been put in place to reduce the risk to anesthesia providers, however there is continued lack of information on providers experiencing short term effects (lethargy, fatigue, headache, slowed cognitive ability, nausea, and mucosal irritation) thereby leading to long-term sequalae (sister chromatid exchanges, micronuclei, chromosomal aberrations, and comet assays).MethodA thirteen item, multiple choice survey was sent to 3,000 anesthesia providers, of which 463 completed the survey. A Chi-square test of independence was used to determine the association between gas exposure and participant self-reported symptoms. A Spearman’s Correlation test was also utilized to interpret this data since both frequency of smelling gas and frequency of symptoms were ordinal variables for which Spearman’s rho correlation was the appropriate measure of association.ResultsThe major findings were that as the frequency of smelling anesthetic gas increased, so too did the frequency of self-reported headaches and fatigue. Spearman’s rho = .148 and .092. P value = .002 and .049, respectively.ConclusionThere have been many efforts to decrease the risk of exposure of anesthesia providers to anesthetic gases. While there is a decrease in reported exposures, indications of possible long-term effects remain a concern in anesthesia providers. Potential implications of exposure could lead to chromosomal aberrations, sister chromatid exchanges, comet assays, spontaneous abortions, and genotoxic effects.

The environmental impact of the Dutch health-care sector beyond climate change: an input–output analysis

Studies suggest that the Dutch health-care sector is responsible for 4-8% of the national carbon footprint, but the environmental footprint of this sector beyond climate change is not well understood. Therefore, we aimed to estimate the environmental footprint of the Dutch health-care sector for a range of environmental impact categories. In this input-output analysis, we used Exiobase (version 3), which contains data on global trade flows and their associated environmental impact, in combination with health-care expenditure data from Statistics Netherlands. We covered the impact categories: climate change, blue water consumption, abiotic material extraction, land use, and total waste generation. The calculated sectoral footprint was the sum of all impacts associated with the operational phase (direct impact) and impacts occurring in the value chain of purchased goods and services (indirect impact) given an expenditure vector. The expenditure vector was the sum of three elements of health-care expenditure: health-care services; pharmaceuticals and chemical products; and medical appliances. We calculated the impact share of health care on the total Dutch consumption footprint. We evaluated the contribution to the impact categories from the categories that composed the expenditure vector. We did a hotspot analysis in which the indirect impact was split according to where (sector, geography, or both) the impact physically occurred. These top-down results were complemented with bottom-up data on emissions from pressurised metered-dose inhalers, anaesthetic gases, and private travel. The health-care sector's share of the national footprint was highest for material extraction (13·0%), followed by blue water consumption (7·5%), climate change (7·3%), land use (7·2%), and waste generation (4·2%). Pharmaceuticals and other chemical products were the biggest contributors to all impacts. The sectors contributing to climate change were more evenly distributed than the sectors contributing to the other impact categories. The mining sector mostly contributed to material extraction and the agricultural sector contributed largely to blue water consumption and land use. The mining sector and the agricultural sector were the main contributors to waste generation. Climate change occurred mainly in the Netherlands, whereas the other impacts mainly occurred abroad. The Dutch health-care sector contributes to a broad set of environmental impact categories beyond climate change. Our results will help stakeholders involved in the health-care sector to pinpoint topics that need to be prioritised and to prevent trade-offs by addressing multiple environmental issues simultaneously. Dutch Ministry of Health, Welfare and Sport.

The Environmental Impact of Orthopaedic Surgery

There are a growing number of opportunities within the field of orthopaedic surgery to address climate change and investigate ways to promote sustainability. Orthopaedic surgeons can take a proactive role in addressing climate change and its impacts within the areas of operating-room waste, carbon emissions from transportation and implant manufacturing, anesthetic gases, and water usage. Future studies are needed to further these initiatives on quantifying and decreasing environmental impact and furthering sustainable use of our resources.

Working towards a greener future in veterinary anaesthesia

Anaesthetic gases can exhibit global warming effects by acting as greenhouse gases. The global warming potentials of these gases vary greatly — with sevoflurane being the most environmentally friendly. Nitrous oxide may also exhibit a global warming effect by direct ozone depletion. Veterinary professionals have the potential to reduce their carbon footprint by making use of targeted anaesthetic choices, low fresh gas flows, and multimodal anaesthesia protocols. Individual practices can also appoint an environmental leader and apply pressure to production companies, as well as provide incentives to staff members to take individual action. New developments within sustainable anaesthesia include metal organic frameworks for gas recapture and potential reuse, as well as the development of an environmentally friendly volatile agent, xenon.

Environmentally friendly absorption of anesthetic gases : First experiences with a commercial anesthetic gas capture system

Anesthetic gases are potent greenhouse gases, which are currently released into the atmosphere where they remain for many years. Strategies to reduce the carbon footprint in anesthesiology without compromising patient safety are urgently needed. Since 2020 several departments of anesthesiology have installed anesthetic gas capture systems with which anesthetic gases can be collected. This article aims to describe the anesthetic gas capture system CONTRAfluran™ and to give an overview of the first experiences in four departments of anesthesiology working with the new device in the daily clinical routine. The CONTRAfluran™ system presents anew concept in the surgical setting that has the potential to reduce the carbon footprint in anesthesiology; however, in order to accurately estimate CO2 equivalent savings, more information concerning the reprocessing and data on the pharmacokinetics of anesthetic gases are needed. Application of the CONTRAfluran™ system in daily clinical routine is feasible when anesthesiologists are aware of specific issues. In order to minimize the carbon footprint, it remains essential to implement the specific recommendations in the position paper of the German Society of Anaesthesiology and Intensive Care medicine (DGAI) and the Professional Association of German Anaesthesiologists (BDA) on ecological sustainability in anesthesiology and intensive care medicine and to support further research.

Depression of synaptic NMDA responses by xenon and nitrous oxide.

In "synapse bouton preparation" of rat hippocampal CA3 neurons, we examined how Xe and N2O modulate N-methyl-D-aspartate (NMDA) receptor-mediated spontaneous and evoked excitatory post-synaptic currents (sEPSCNMDA and eEPSCNMDA) excluded extrasynaptic, glial and other neuronal tonic currents. This preparation is a mechanically isolated single neuron attached with nerve endings (boutons) preserving normal physiological function and promotes the exact evaluation of sEPSCNMDA and eEPSCNMDA These sEPSC and eEPSC are elicited by spontaneous glutamate (Glu) release from many homologous glutamatergic boutons and by focal paired-pulse electric stimulation of a single bouton, respectively. The s/eEPSCAMPA/KA and s/eEPSCNMDA were isolated pharmacologically by their specific antagonists. Thus, independent contributions of pre- and postsynaptic responses be could also quantified. All kinetic properties of s/eEPSCAMPA/KA and s/eEPSCNMDA were detected clearly. The s/eEPSCNMDA showed smaller amplitude, slower rise and 1/e decay time constant (τDecay) than s/eEPSCAMPA/KA Xe (70%) and N2O (70%) significantly decreased the frequency and amplitude without altering the τDecay of sEPSCNMDA They also decreased the amplitude but increased the Rf and PPR without altering the τDecay of the eEPSCNMDA These data show clearly that "synapse bouton preparation" can be an accurate model for evaluating s/eEPSCNMDA Such inhibitory effects of gas anesthetics are primarily due to presynaptic mechanisms. Present results may explain partially the powerful analgesic effects of Xe and N2O. Significance Statement We could record pharmacologically isolated sEPSCNMDA and eEPSCNMDA and clearly detect all kinetic parameters of sEPSCNMDA and eEPSCNMDA at synaptic levels by using "synapse bouton preparation" of rat hippocampal CA3 neurons. We found that Xe and N2O clearly suppressed both sEPSCNMDA and eEPSCNMDA Different from previous studies, present results suggest that Xe and N2O predominantly inhibit the NMDA responses by presynaptic mechanisms.

Implementation and acceptability of anaesthetic agent capture technology

Background: Anaesthetic gases contribute significantly to greenhouse gas emissions. At present, all hospitals rely on anaesthetic gas scavenging systems (AGSS) to remove patient exhaled anaesthetic gases from the anaesthetic room and operating theatre directly into the atmosphere. Novel technology can now capture, store locally and later recycle these volatile anaesthetic agents, almost eliminating their greenhouse gas contribution. CONTRAfluran is such a system which passively absorbs anaesthetic gases from the expiratory limb of the anaesthetic breathing circuit into canisters, which are collected and processed, allowing for desflurane, sevoflurane, and isoflurane to be recycled and later reused.

Cutting carbon, cutting costs: a quality improvement project increasing volatile anaesthetic efficiency

Background: As the recent UN Climate Change Conference in Glasgow highlighted, the world is battling a climate crisis and urgent action is required to turn the tide. Anaesthesia has a direct impact on the environment, and more specifically anaesthetic gases, with 5% of a hospital’s carbon footprint attributable to them.1–3 Indeed, 42% of carbon emissions generated during a surgical procedure are from anaesthetic gases. The aim of this quality improvement project was to improve the efficiency of volatile anaesthetic usage, by comparing our anaesthetic consumption levels, to patient uptake over a period of months after regular departmental educational interventions.

Watford Anaesthetics going greener: reducing our emissions one volatile at a time

Background: Anaesthetic gases are responsible for 3% of the NHS carbon footprint. The NHS Long Term Plan aims to reduce this by 40% by: shifting away from desflurane use; effective capture, destruction, or reuse of volatiles and reduction in atmospheric release from leftover nitrous oxide gas canisters.1 A 240 ml bottle of desflurane costs £63, producing 886 kg of carbon dioxide emissions (CO2e) compared with a 250 ml bottle of sevoflurane which costs £44.99 producing 49 kg.2 We aim to reduce our carbon footprint by reducing desflurane use, encouraging low flow anaesthesia and use of TIVA. Methods: A departmental questionnaire was sent to assess knowledge of the environmental impact anaesthetic gases cause and gauge desflurane use. The pharmacy provided procurement data for sevoflurane, desflurane, and 2% propofol for 2019. Our intervention was to remove desflurane from all anaesthetic machines after consultation. TIVA training for trainees was provided and 6-month pharmacy procurement data obtained. Results: The majority (89%) use low flow anaesthesia with volatiles and interest in TIVA use is increasing. The inaccessibility of desflurane has led to a 100% decrease in use this 6-month period. Over a year, this could lead to savings of £26 124.68 and 455 240 kg CO2e (Table 5).Table 5Comparison of cost and CO2e usage before and after removal of desflurane.AnaestheticBottles usedTotal cost (£)Total CO2e (kg)2019August 21–January 222019Projected 20222019Projected 2022Sevoflurane40227518 085.9824 744.5019 69826 950Desflurane522032 8660462 4920Propofol 2%119061821422224.8000Total53 093.9826 969.30482 19026 950 Open table in a new tab Conclusions: No negative impact from desflurane removal has been reported. Equipment for TIVA use including bispectral index (BIS) monitoring is now widely available in our department. Next steps include re-auditing and comparing pharmacy procurement data from 2019 to 2022. We are looking to expand our ‘greener’ movement into re-capturing N2O and improving recycling methods. 1.England.nhs.uk. 2021. Delivering a ‘net zero’ national health service. Available at: https://www.england.nhs.uk/greenernhs/wp-content/uploads/sites/51/2020/10/delivering-a-net-zero-national-health-service.pdf (accessed 25 March 2022)2.Pierce J. The environment, the gas bill and the route to sustainable anaesthesia. Rcoa.ac.uk. 2013. Available at: https://www.rcoa.ac.uk/sites/default/files/documents/2019-09/Bulletin82-Nov2013-Pages39-41.pdf (accessed 25 March 2022).

One step closer towards a greener NHS: decommissioning of piped nitrous oxide manifolds

Background: Nitrous oxide (N2O) is a widely used anaesthetic gas that is both a powerful greenhouse agent with 298 times the global warming potential of carbon dioxide (CO2)1 and detrimental to the ozone layer. According to NHS Lothian recent investigations, massive N2O leakage from piped manifold systems has been highlighted.2 One simple solution is to decommission N2O manifolds, with small N2O cylinders on the anaesthetic machines reserved for occasional usage. Hence, this project is initiated at Perth Royal Infirmary (PRI) with the goal of decommissioning the piped N2O manifold facility to meet the NHS Scotland Zero N2O emission by year 2027. Methods: A survey was conducted among all anaesthetists in PRI Anaesthetic department to evaluate their N2O usage preference and feasibility of decommissioning the piped N2O manifold. The N2O supply data provided by the pharmacy team was over a period of 10 months for the year 2021–22. To quantify the clinical usage at PRI, we captured the cumulative N2O usage over a 20-day period, using the data obtained from the service mode on each anaesthetic machine. From there, we extrapolated and calculated the annual estimated supply, usage, and wastage amount. Results: From the survey, all anaesthetists reported that their N2O usage is very low. Seventy-one percent of anaesthetists have decreased N2O usage over the past 5 yr, and there are no objections to the decommissioning of the piped N2O manifold. Based on our calculations, only 5475 L N2O are estimated to be consumed as opposed to 126 890 L supplied per annum. This demonstrates that as much as 96% or 121 415 L N2O are wasted. Financially, this is equivalent to 13.5 size G N2O cylinders worth £3145 per annum. To put into perspective, this corresponds to 64 964 kg CO2 equivalent emission or a staggering 541 366 km of car travel. Conclusions: We found significant wastage of N2O, unnecessary long-term financial expenditure, and adverse consequences to planetary health that could all be prevented. Our next step is to execute the plan of decommissioning piped N2O manifolds in accordance with the interim protocol for decommissioning set by the Scottish Government. Although this is a small step towards a greener sustainable future, multidisciplinary efforts from all related departments are essential in making this vision a reality. Eventually, re-audit will be carried out to evaluate the outcome of this action before rolling this improvement plan out to all sites within NHS Tayside. 1.Myhre G, Shindell D, Breon FM, et al. Anthropogenic and natural radiative forcing. In: IPCC Fifth Assessment Report. 2013.2.Chakera A, Fennell-Wells A, Allen A. Nitrous oxide project: piped nitrous oxide waste reduction strategy. Association of Anaesthetists, 2021 Jan 15. Available from: https://anaesthetists.org/Home/Resources-publications/Environment/Nitrous-oxide-project.

Energy-based advection modelling using bond graphs

Advection, the transport of a substance by the flow of a fluid, is a key process in biological systems. The energy-based bond graph approach to modelling chemical transformation within reaction networks is extended to include transport and thus advection. The approach is illustrated using a simple model of advection via circulating flow and by a simple pharmacokinetic model of anaesthetic gas uptake. This extension provides a physically consistent framework for linking advective flows with the fluxes associated with chemical reactions within the context of physiological systems in general and the human physiome in particular.

Identifying barriers to the use of total intravenous anaesthesia: a pan-London multi-centre survey for the assessment of clinician rationale

Background: The impending climate crisis represents one of the greatest threats to global health over the coming century. Anaesthetic gases represented 2% of the NHS’ total carbon footprint,1 and with the NHS committing to becoming carbon neutral by 2045, reduction of waste greenhouse gases will need to play a vital role in this. We therefore sought to understand the clinician rationale for the use of inhalation gases over TIVA through means of a questionnaire, with particular focus on agents with the greatest environmental impact: desflurane and nitrous oxide (N2O).

Lost in the Ether: The Environmental Impact of Anesthesia

Health care systems contribute a significant amount of global greenhouse gas (GHG) emissions, and operating rooms are among the most resource intensive and waste producing locations in hospitals. Surgery's high environmental impact is due to many factors including: widespread use of anesthetic and medical gases; pharmaceutical production and waste; substantial non-recycled waste from disposable single-use devices; and energy consumption for equipment use and reprocessing, in addition to the significant energy needed for heating, cooling and ventilation of ORs. As the urgency of addressing global climate change increases, health care providers must do all they can to minimize the environmental impacts of health care in a sustainable, yet safe manner. Thoughtful management techniques by anesthesiologists, surgeons, and operating room staff before, during, and after procedures can minimize the environmental impact of surgery while maintaining cost-efficient, excellent patient care.

Characterizing the Heart Rate Effects From Administration of Sugammadex to Reverse Neuromuscular Blockade: An Observational Study in Patients.

Reversal of neuromuscular blockade (NMB) with sugammadex can cause marked bradycardia and asystole. Administration of sugammadex typically occurs in a dynamic period when anesthetic adjuvants and gas concentrations are being titrated to achieve emergence. This evaluation examined the heart rate (HR) responses to sugammadex to reverse moderate to deep NMB during a steady-state period and sought mechanisms for HR changes. Patients with normal sinus rhythm, who were undergoing elective surgery that included rocuronium for NMB, were evaluated. After surgery, while at steady-state surgical depth anesthesia with sevoflurane and mechanical ventilation, patients received either placebo or 2 or 4 mg/kg of sugammadex to reverse moderate to deep NMB. Study personnel involved in data analysis were blinded to treatment. Continuous electrocardiogram (ECG) was recorded from the 5 minutes before and 5 minutes after sugammadex/placebo administration. R-R intervals were converted to HR and averaged in 1-minute increments. The maximum prolongation of an R-R interval after sugammadex was converted to an instantaneous HR. A total of 63 patients were evaluated: 8 received placebo, and 38 and 17 received 2 and 4 mg/kg sugammadex. Age, body mass index, and patient factors were similar in groups. Placebo did not elicit HR changes, whereas sugammadex caused maximum instantaneous HR slowing (calculated from the longest R-R interval), ranging from 2 to 19 beats/min. There were 7 patients with maximum HR slowing >10 beats/min. The average HR change and 95% confidence interval (CI) during the 5 minutes after 2 mg/kg sugammadex were 3.1 (CI, 2.3-4.1) beats/min, and this was not different from the 4 mg/kg sugammadex group (4.1 beats/min [CI, 2.5-5.6]). HR variability derived from the standard deviation of consecutive R-R intervals increased after sugammadex. Sugammadex to reverse moderate and deep NMB resulted in a fast onset and variable magnitude of HR slowing in patients. A difference in HR slowing as a function of dose did not achieve statistical significance. The observational nature of the investigation prevented a full understanding of the mechanism(s) of the HR slowing.

Comparison of Extubation of Patients in Prone versus Supine Position in workers Undergoing Lumbar Disc Surgery

Introduction: This study compared the extubation of patients in prone versus supine positions in patients undergoing lumbar disc surgery.
 Material and Methods: In this single-blind clinical trial, 60 patients who were candidates for elective lumbar disc surgery were selected and randomly assigned into two groups of 30 patients. All patients primarily underwent surgery in the prone position. After surgery and discontinuation of anesthesia gases (T0), patients were assigned into two groups, prone and supine. From T0 to extubation time, heart rate, systolic and diastolic blood pressure, mean arterial pressure, Spo2, cough severity, and secondary complications after extubation such as laryngospasm and shortness of breath were measured and recorded in both groups. 
 Results: The results showed that in all the variables under study, the supine group had higher values than the prone group. There was a significant difference in oxygen pressure between the two groups, and the prone group had a more suitable status than the supine group (P=0.02). The incidence of cough was higher in the supine group compared to the prone group, and the observed difference was significant (P=0.001).
 Conclusion: Based on the findings of this study, maintaining the prone position after lumbar disc surgery for extubation causes the patient to be less affected by the change of position and is in a superior status in terms of coughing and oxygen pressure.

Translational design for limited resource settings as demonstrated by Vent-Lock, a 3D-printed ventilator multiplexer

BackgroundMechanical ventilators are essential to patients who become critically ill with acute respiratory distress syndrome (ARDS), and shortages have been reported due to the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).MethodsWe utilized 3D printing (3DP) technology to rapidly prototype and test critical components for a novel ventilator multiplexer system, Vent-Lock, to split one ventilator or anesthesia gas machine between two patients. FloRest, a novel 3DP flow restrictor, provides clinicians control of tidal volumes and positive end expiratory pressure (PEEP), using the 3DP manometer adaptor to monitor pressures. We tested the ventilator splitter circuit in simulation centers between artificial lungs and used an anesthesia gas machine to successfully ventilate two swine.ResultsAs one of the first studies to demonstrate splitting one anesthesia gas machine between two swine, we present proof-of-concept of a de novo, closed, multiplexing system, with flow restriction for potential individualized patient therapy.ConclusionsWhile possible, due to the complexity, need for experienced operators, and associated risks, ventilator multiplexing should only be reserved for urgent situations with no other alternatives. Our report underscores the initial design and engineering considerations required for rapid medical device prototyping via 3D printing in limited resource environments, including considerations for design, material selection, production, and distribution. We note that optimization of engineering may minimize 3D printing production risks but may not address the inherent risks of the device or change its indications. Thus, our case report provides insights to inform future rapid prototyping of medical devices.

Effect of simultaneous exposure to inhalational anesthetics and radiation on the adaptive response in operating room personnel.

Some operating room personnel, such as orthopedic surgeons, are exposed simultaneously to inhalational anesthetics (IAs) and radiation that both can cause DNA damage. Some studies have shown that low doses of radiation reduce DNA damage when the cells are followed by a higher dose of the same or related agent. This study, therefore, set out to compare DNA damage in the anesthesiologists, radiologists, orthopedic surgeons, and healthcare staff (non-exposed group). In this cross-sectional study, breathing zone concentrations of anesthetic gas nitrous oxide (N2O) were measured in the studied groups using standard method. Additionally, DNA damage was measured by micronucleus (MN) assay. The mean concentrations of N2O in the anesthesiologists and orthopedic surgeons were 450.27 ± 327.44ppm and 313.64 ± 216.14ppm, respectively. The mean annual exposure to X-rays radiation in radiologists and orthopedic surgeons was 15.65 ± 8.46 mSy/year and 3.56 ± 1.32 mSy/year, respectively. MN frequencies were significantly higher in anesthesiologists and radiologists exposed to IAs and X-rays radiation respectively than in the non-exposed healthcare staff. While, there were no statistically significant differences between MN frequencies of orthopedic surgeons exposed to both IAs and radiation and healthcare staff.These findings suggest that an earlier exposure of orthopedic surgeons to a small dose of ionizing radiation can increase their resistance to genotoxicity caused by high doses of N2O, a phenomenon that is called adaptive response.

Evaluation of genetic instability, oxidative stress, and metabolism-related gene polymorphisms in workers exposed to waste anesthetic gases.

Professionals who work in operating rooms (ORs) may be exposed daily to waste anesthetic gases (WAGs) due to the use of inhalational anesthetics. Considering the controversial findings related to genetic damage and redox status in addition to a lack of knowledge about the effect of polymorphisms in genes related to phase I and II detoxification upon occupational exposure to WAGs, this cross-sectional study is the first to jointly evaluate biomarkers of genetic instability, oxidative stress, and susceptibility genes in professionals occupationally exposed to high trace amounts of halogenated (≥ 7ppm) and nitrous oxide (165ppm) anesthetics in ORs and in individuals not exposed to WAGs (control group). Elevated rates of buccal micronucleus (MN) and nuclear bud (NBUD) were observed in the exposure group and in professionals exposed aged more than 30years. Exposed males showed a higher antioxidant capacity, as determined by the ferric reducing antioxidant power (FRAP), than exposed females; exposed females had higher frequencies of MN and NBUD than nonexposed females. Genetic instability (MN) was observed in professionals with greater weekly WAG exposure, and those exposed for longer durations (years) exhibited oxidative stress (increased lipid peroxidation and decreased FRAP). Polymorphisms in metabolic genes (cytochrome P450 2E1 (CYP2E1) and glutathione S-transferases (GSTs)) did not exert an effect, except for the effects of the GSTP1 (rs1695) AG/GG polymorphism on FRAP (both groups) and GSTP1 AG/GG and GSTT1 null polymorphisms, which were associated with greater FRAP values in exposed males. Minimizing WAG exposure is necessary to reduce impacts on healthcare workers.

Use of Ketamine or Xylazine to Provide Balanced Anesthesia with Isoflurane in C57BL/6J Mice.

Balanced anesthesia-the use of a combination of drugs to achieve a desired anesthetic plane-offers many benefits, including smoother induction and recovery and fewer adverse effects than occur with individual drugs. Although premedication prior to inhalant anesthesia is routine in other species, mice are commonly induced with gas anesthesia alone. The hypothesis of this study was that premedication with ketamine or xylazine would safely reduce the stress of isoflurane induction and lower the minimum alveolar concentration (MAC) of isoflurane. Young adult male and female C57BL/6J mice were premedicated with ketamine (100 mg/kg), xylazine (4 mg/kg), or isotonic crystalloid (0.1 mL) and were used in 4 experiments. First, isoflurane induction was video recorded under all test conditions, and the videos were scored according to a behavioral ethogram to identify signs of distress. Mice in the ketamine group experienced tremors and ataxia before and dur- ing induction. Therefore, ketamine was given after induction with isoflurane in subsequent experiments. Second, the MAC value for each anesthetic protocol was determined by using quantal and bracketing analysis. Third, mice were anesthetized according to the 3 protocols, and vital parameters were monitored for 60 min. Finally, anesthetized mice were challenged with hypoxia and hypovolemia, and vital parameters were monitored. Premedication with xylazine significantly reduced the stress scores for isoflurane induction (control, 7.3 ± 1.5; ketamine, 6.0 ± 3.0; xylazine, 3.1 ± 1.0). Ketamine and xylazine both reduced the MAC of isoflurane (control, 1.89%; ketamine, 0.96%; xylazine, 1.20%). All mice survived 60 min of anesthesia and the hypoxia-hypovolemia challenge. Premedication with xylazine reduced the stress of induction and lowered the necessary dose of isoflurane in C57BL/6J mice to maintain a surgical plane of anesthesia. We recommend administering xylazine before isoflurane induction and anesthesia of healthy mice that are undergoing procedures in which 100% oxygen is provided and anticipated blood loss is less than 10% to 15% of the total blood volume.

589 Reducing Single-Use Surgical Instruments During Laparoscopic Appendicectomy: Using Sustainable Quality Improvement as a Catalyst to Encourage Wider Behavioural Change in a Surgical Department

Abstract Aim Consumables are responsible for 32% of surgery associated CO2 emissions after excluding anaesthetic gases. We aimed to reduce the carbon footprint of laparoscopic appendicectomies by addressing equipment issues whilst also meeting the triple bottom line of financial, environmental, and social impacts. Method In a single-centre, a questionnaire was distributed to establish the frequency of, and reasons for, single-use instrument use. A separate questionnaire identified areas for improvement within existing appendicectomy sets. An evaluation of 25 appendicectomies was undertaken, documenting single-use instrument usage. New appendicectomy sets were developed, including additional reusable instruments, and procuring new ports, trialling these in subsequent appendicectomies. Financial impact was calculated based on current procurement prices. Environmental impact was calculated by carbon costing the production, transport and disposal of consumables using published emission factors. Social impact was assessed using staff surveys. Results 110 single-use instruments were opened in 25 appendicectomies. Our trust performs ∼500 appendicectomies/year, therefore equating to ∼2180 instruments/year that could be avoided by using reusable alternatives. Based on an estimated 75% reduction in consumables, the new set saves £34,423 and 512kg CO2e per year over the predicted seven-year life span of the instruments. Based on existing practice, the capital investment required for new instruments (£19,731) will pay for itself within six months. Reduced consumable reliance decreases the volume of waste being incinerated, tackling scope one emissions and local air pollution. Conclusions These results demonstrate that sustainable changes can be cost saving and reduce carbon emissions. This approach has translational potential across all surgical specialities using single-use instruments.