Special article: general anesthetic gases and the global environment

[Remimazolam-Update on basic pharmacologic principles and clinical potential]

In recent years the still relatively new short-acting benzodiazepine remimazolam has been approved and clinically implemented in several countries and regions. Remimazolam is also now approved in the EU and the market launch in Germany is expected in the not too distant future. This is therefore a good point in time to summarize the current evidence for various areas of application, including general anesthesia, sedation and intensive care medicine as well as different dosing schemes.

The safety of nitrous oxide: glass half-full or half-empty?

A systematic review of clinical trials confirms that including nitrous oxide in the gas mixture for general anaesthesia has minor short-term benefits and does not impact most patient safety outcomes. However, no risk-benefit analysis of nitrous oxide should ignore its known environmental effects. If continued nitrous oxide use is supported, strategies to minimise and monitor the contribution of medical nitrous oxide to global warming are vital.

A randomised controlled trial comparing quality of recovery between desflurane and isoflurane inhalation anaesthesia in patients undergoing ophthalmological surgery at a tertiary hospital in South Africa (DIQoR trial)

Background

The patient's experience of their postoperative recovery is an important perioperative outcome, with the 15-item quality of recovery scale (QoR-15) recommended as a standardised outcomes measure. Desflurane has a faster emergence from anaesthesia compared with other volatile anaesthetics, but it is uncertain whether this translates to better subjective quality of recovery. The hypothesis for this study is that patients receiving desflurane for maintenance of anaesthesia would have better postoperative quality of recovery than patients receiving isoflurane.

Methods

Male and female adult patients undergoing ophthalmological surgery under general anaesthesia were randomly allocated to receive desflurane or isoflurane for maintenance of anaesthesia. The primary outcome was to compare postoperative QoR-15 scores. Secondary outcomes included comparing preoperative QoR-15 scores, volatile agent consumption, and time spent in the recovery room.

Results

Data from 164 patients were analysed (80 desflurane, 84 isoflurane). Median (Q1, Q3) postoperative QoR-15 scores were not significantly different (desflurane: 145 [141, 148], isoflurane: 144 [139, 147], 95% confidence interval 0-3, P=0.176, minimal clinically important difference=8). Median (Q1, Q3) volatile agent consumption was 15.4 (12.5, 19.3) ml hr-1 in the desflurane group, and 7.4 (5.9, 9.7) ml hr-1 in the isoflurane group. Median (Q1, Q3) time spent in the recovery room was significantly shorter in the desflurane group (desflurane: 18 [13, 23]; isoflurane: 25 [19, 32], 95% confidence interval -10 to 5, P<0.001).

Conclusions

This study found no difference in quality of recovery between patients who received desflurane or isoflurane for maintenance of general anaesthesia during ophthalmological surgery. A shorter time in the recovery room was not associated with improved QoR-15 scores.

Clinical trial registration

NCT04188314.

The science of climate change and the effect of anaesthetic gas emissions

The dedication of the international anaesthetic community to reducing the environmental impact of healthcare is important and to be celebrated. When this is underpinned by robust science, it has the potential to make a real difference. However, volatile anaesthetic agents have been widely promoted in the medical literature as damaging to the climate, leading to a drive to remove them from clinical practice. This is based on notional 'CO2 -equivalent' values created using the simple emission metric known as the global warming potential. Here, we assert that when proper consideration is given to the science of climate change, volatile anaesthetic gas emissions cannot be simply equated to real carbon dioxide emissions, and that their climate impact is vanishingly small. This paper gives anaesthetists a framework to make informed choices founded on climate science and calls for attention to be refocused on the urgent need to reduce the real carbon dioxide emissions associated with healthcare.

The path to Net Zero carbon emissions for veterinary practice

The urgent need to reduce greenhouse gas emissions in line with the Paris Agreement is a compelling reason for the entire veterinary profession to act on climate change because of its impact on animal health. The aim of this perspective is to provide a business framework that veterinary practices can use to implement the path to Net Zero carbon emissions. Practice management is identified as a key stakeholder capable of implementing significant change within the sector. Climate related business opportunities and challenges are identified and integrated into a stepwise process for practices to follow. The pathway requires establishing a culture of sustainability within the veterinary team, measuring and reporting emissions, setting targets and systematically prioritizing reductions. Practices can begin this process immediately by reducing emissions under direct control of the business (Scope 1) and emissions from electricity purchases (Scope 2). To complete the pathway, emissions from all other activities (Scope 3) will need to be reduced and offset. Reduction of Scope 3 emissions is more challenging and will require collaboration between all supply chain stakeholders. The progression of climate change is now inevitable and a proactive approach from veterinary leaders, in particular practice management, will provide new opportunities, manage risks and inspire the broader veterinary sector to join their efforts to achieve a better future for animal health.

Minimal fixed flow anesthesia for off-pump coronary artery bypass surgery: A parallel randomized trail

Objectives

The aim of the present study was to test a safety of a fixed minimal (0.5 l/min) fresh gas flow (FGF) anesthesia as a method ensuring adequate oxygenation during off-pump coronary artery bypass grafting operations.

Design

A randomized, prospective study.

Setting

Single-center clinical hospital affiliated with a university.

Participants

208 patients underwent off-pump coronary artery bypass surgery.

Interventions

All patients received endotracheal inhalational anesthesia with fixed minimal FGF. Half of them were anesthetized by sevoflurane and another half by isoflurane. The fresh (carrier) gas was pure oxygen in the control groups and a mixture of medical air and oxygen (FiO2 0.8) in the trial groups.

Measurements and main results

In the control groups inhaled oxygen concentration changed minimally during the operation. In the trial groups in 28.8 % of cases inhaled oxygen concentration dropped below preliminary margin (0.4). Body surface area (BSA) (B = 38.7; p = 0.002) and patient's age (B = -0.47; p = 0.004) were retained into final logistic regression model as independent predictors. We divided BSA into subcategories and analyzed data by survival cox regression with Forward LR method. Patients with BSA>2.3 (Exp.B = 183) and BSA [2.2-2.3] (Exp.B = 59) had high chance to get less than 0.4 of inhaled oxygen concentration compared to the patients with BSA <2.0 (p < 0.001).Exp(B) or OR for the patients' age as independent predictor tested in multiple logistic regression was 0.628 In other words, for every year less the patient had 1/0.628 = 1.6 times more chance to reach the preliminary low margin (0.4) of oxygenation.

Conclusions

Fixed minimal FGF 0.5 l/min with FiO2 0.8 may not be sufficient for the younger patients with BSA >2.0 to maintain inhaled oxygen concentration above 0.4. Using pure oxygen as a carrier gas during fixed minimal flow long term anesthesia is much safer and more reliable.

Nitrous Oxide Use in Australian Health Care: Strategies to Reduce the Climate Impact

Nitrous oxide is a useful inhaled analgesic. Due to its high global warming potential and ozone-depleting properties, the nitrous oxide emissions related to health care are being increasingly scrutinized. In this narrative review, we will discuss the clinical uses of nitrous oxide relevant to anesthetists, in addition to its contribution as a greenhouse gas. Using available data from Australia, we will explore potential strategies for reducing the impact of those emissions, which are likely to be applicable in other countries. These include destruction of captured nitrous oxide, minimizing nitrous oxide waste and reducing clinical use. Anesthesia clinicians are well placed to raise awareness with colleagues and consumers regarding the environmental impact of nitrous oxide and to promote cleaner alternatives. Reducing use is likely to be the most promising reduction strategy without large-scale changes to infrastructure and subsequent delay in action.

Guidelines for reducing the environmental impact of general anaesthesia

OBJECTIVE

To provide guidelines for reducing the environmental impact of general anaesthesia.

DESIGN

A committee of ten experts from SFAR and SF2H and SFPC learned societies was set up. A policy of declaration of competing interests was applied and observed throughout the guideline-writing process. Likewise, it did not benefit from any funding from a company marketing a health product (drug or medical device). The committee followed the GRADE® method (Grading of Recommendations Assessment, Development and Evaluation) to assess the quality of the evidence on which the recommendations were based.

METHODS

We aimed to formulate recommendations according to the GRADE® methodology for three different fields: anaesthesia vapours and gases; intravenous drugs; medical devices and the working environment. Each question was formulated according to the PICO format (Population, Intervention, Comparator, Outcome). The literature review and recommendations were formulated according to the GRADE® methodology.

RESULTS

The experts' work on the synthesis and application of the GRADE® method led to the formulation of 17 recommendations. Since the GRADE® method could not be entirely applied to all of the questions, some of the recommendations were formulated as expert opinions.

CONCLUSION

Based on strong agreement between experts, we produced 17 recommendations designed to guide reducing the environmental impact of general anaesthesia.

Assessing the potential climate impact of anaesthetic gases

There is increasing concern within the health-care community about the role care delivery plays in environmental degradation, sparking research into how to reduce pollution from clinical practice. Inhaled anaesthetics is a particular research area of interest for two reasons. First, several gases are potent greenhouse gases, and waste gas is mostly emitted directly to the environment. Second, there are options to reduce gas waste and substitute medications and procedures with fewer embodied emissions while delivering high-quality care. Performance improvements are contingent on a proper understanding of the emission estimates and climate metrics used to ensure consistent application in guiding mitigation strategies and accounting at various scales. We review the current literature on the environmental impact and the estimation of the potential climate forcing of common inhaled anaesthetic drugs: desflurane, sevoflurane, isoflurane, methoxyflurane, and nitrous oxide.

The impact of withholding nitrous oxide in labour during the COVID-19 pandemic on maternal and neonatal outcomes

Nitrous oxide is commonly used in Australia for labour analgesia. Its use in labour is potentially associated with aerosol generation. During the first wave of the COVID-19 pandemic of 2020, nitrous oxide was suspended on many birthing units to reduce the risk of transmission. We aimed to determine the impact of withholding nitrous oxide for labour analgesia, during the COVID-19 pandemic, on epidural rates, opioid analgesia use, and maternal and neonatal outcomes. Withholding nitrous oxide for labour analgesia did not alter epidural rates but did significantly increase opioid analgesia use. Caesarean section rates, post-partum blood loss and neonatal APGAR scores did not change.

Reduction of greenhouse gases emission through the use of tiletamine and zolazepam

Isoflurane is an anaesthetic gas widely used in both human and veterinary medicine. All currently used volatile anaesthetics are ozone-depleting halogenated compounds. The use of total intravenous anaesthesia (TIVA) allows to induce the effect of general anaesthesia by administering drugs only intravenously without the use of anaesthetic gases. This allows you to create a protocol that is safe not only for the patient, but also for doctors and the environment. However, so far, no anaesthetic protocol based on induction of anaesthesia with tiletamine-zolazepam without the need to maintain anaesthesia with anaesthetic gas has been developed. Our study showed that the use of this combination of drugs for induction does not require the use of additional isoflurane to maintain anaesthesia. Thanks to Dixon's up-and-down method we proved that with the induction of anaesthesia with tiletamine-zolazepam at a dose of 5 mg/kg the use of isoflurane is not needed to maintain anaesthesia in minimally invasive surgical procedures. Until now, this dose has been recommended by the producer for more diagnostic than surgical procedures or for induction of general anaesthesia. The maintenance was required with anaesthetic gas or administration of another dose of the tiletamine-zolazepam. The results obtained in this study will allow for a significant reduction in the consumption of isoflurane, a gas co-responsible for the deepening of the greenhouse effect, having a negative impact on patients and surgeons. These results are certainly the first step to achieving a well-balanced and safe TIVA-based anaesthetic protocol using tiletamine-zolazepam, the obvious goal of which will be to maximize both the safety of the patient, people involved in surgical procedures, and the environment itself. Being aware of the problem of the greenhouse effect, we are committed to reducing the consumption of anaesthetic gases by replacing them with infusion agents.

Building sustainable and resilient surgical systems: A narrative review of opportunities to integrate climate change into national surgical planning in the Western Pacific region

Five billion people lack access to surgical care worldwide; climate change is the biggest threat to human health in the 21st century. This review studies how climate change could be integrated into national surgical planning in the Western Pacific region. We searched databases (PubMed, Web of Science, and Global Health) for articles on climate change and surgical care. Findings were categorised using the modified World Health Organisation Health System Building Blocks Framework. 220 out of 2577 records were included. Infrastructure: Operating theatres are highly resource-intensive. Their carbon footprint could be reduced by maximising equipment longevity, improving energy efficiency, and renewable energy use. Service delivery Tele-medicine, outreaches, and avoiding desflurane could reduce emissions. Robust surgical systems are required to adapt to the increasing burden of surgically treated diseases, such as injuries from natural disasters. Finance: Climate change adaptation funds could be mobilised for surgical system strengthening. Information systems: Sustainability should be a key performance indicator for surgical systems. Workforce: Surgical providers could change clinical, institutional, and societal practices. Governance: Planning in surgical care and climate change should be aligned. Climate change mitigation is essential in the regional surgical care scale-up; surgical system strengthening is also necessary for adaptation to climate change.

Effects of Sevoflurane on Apoptosis of Myocardial Cells in IRI Rats

Background

Cardiomyocyte apoptosis functions essentially in ischemia/reperfusion- (I/R-) induced myocardial injury. It is suggested that autophagy is widely implicated in the regulation of cell survival and death. Sevoflurane, as a largely used inhalational general anesthetic, has been shown to have a protective effect on cardiomyocytes. However, it was yet elusive on the underlying mechanisms.

Aim

The objective of this study is to investigate the association of sevoflurane-mediated cardioprotective effects with autophagy regulation.

Methods

An in vitro hypoxia model was established in primary cardiomyocytes from fresh myocardial tissue of the rats. The apoptosis rate of myocardial cells treated with hypoxia and treated with sevoflurane was measured. Western blot and immunocytochemical assay were used to measure the protein expression. The cell proliferation rate and cell apoptosis were measured using the MTT assay and flow cytometry, respectively.

Results

The expression of apoptotic proteins including B cell lymphoma-2 (Bcl-2), CCAAT/enhancer-binding protein homologous protein (CHOP), glucose-regulated protein 78 (GRP78), and Bcl-2-associated X protein (BAX) in myocardium treated with sevoflurane was significantly lower than that in myocardium treated with hypoxia. The expression of adhesion proteins such as intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin in myocardium treated with sevoflurane was higher than that in myocardium treated with hypoxia, suggesting better connectivity of the myocardium.

Conclusion

Sevoflurane treatment reduced the apoptosis of myocardial cells after hypoxia treatment.

Minimal fresh gas flow sevoflurane anesthesia and postoperative acute kidney injury in on-pump cardiac surgery: a randomized comparative trial

BACKGROUND

Compound A is generated by sevoflurane when it reacts with carbon dioxide absorbers with strong bases at minimal fresh gas flow (FGF) and is nephrotoxic in animals. No conclusive data has shown increased risk in humans. The aim of this study was to investigate if minimal FGF promotes an increase in the incidence of acute kidney injury (AKI) when compared to high FGF in patients undergoing on-pump cardiac surgery under sevoflurane anesthesia.

METHODS

Two hundred and four adult patients scheduled for on-pump cardiac surgery under sevoflurane anesthesia were randomly allocated to two groups differentiated by FGF: minimal FGF (0.5 L.min^-1) or high FGF (2.0 L.min^-1). Baseline creatinine measured before surgery was compared daily to values assayed on the first five postoperative days, and 24-hour urinary output was monitored, according to the KDIGO (Kidney Disease Improving Global Outcomes) guideline to define postoperative cardiac surgery-associated acute kidney injury (CSA-AKI). Creatinine measurements were also obtained 20 and 120 days after hospital discharge.

RESULTS

Postoperative AKI occurred in 55 patients, 26 patients (29.5%) in the minimal FGF group and 29 patients (31.5%) in the high FGF group (p = 0.774). Twenty days after discharge, 11 patients (6.1%) still had CSA-AKI and 120 days after discharge only 2 patients (1.6%) still had CSA-AKI.

CONCLUSIONS

When compared to high FGF, minimal FGF sevoflurane anesthesia during on-pump cardiac surgery is not associated with increased risk of postoperative AKI in this population at high risk for renal injury.

[New challenges for anesthesia due to the climate change]

BACKGROUND

The climate crisis is the most serious threat to global health in the twenty-first century. In western countries 5-10% of all greenhouse gas emissions originate from the healthcare sector and the main contributing factors are energy-intense departments (intensive care units, operating suits and prehospital emergency services).

OBJECTIVE

The aim of this review is to provide background knowledge and practical ideas to achieve climate-neutral hospitals.

MATERIAL AND METHODS

Narrative review with information on the topics of (I) volatile anesthetics as greenhouse gases, (II) energy supply in hospitals and (III) solid waste management.

RESULTS AND CONCLUSION

(I) Volatile anesthetics are highly potent greenhouse gases, especially desflurane has a major global warming potential. Total intravenous anesthesia (TIVA) with propofol or regional anesthetic techniques have a much lower impact on the climate. (II) Using sustainable energy sources as well as initiating energy sparing techniques, such as light-emitting diodes (LED) and motion sensors, can reduce CO₂ emissions. (III) Waste can be managed by the reduce, reuse, recycle, rethink and research concept. Doctors should actively contribute to reach the climate goals.

Efficacy of dexmedetomidine on peritoneal dialysis catheter insertion

PURPOSE

Dexmedetomidine (DEX) is a sedative agent with minimal respiratory and hemodynamic effects. The present study aimed to evaluate its effectiveness in peritoneal dialysis (PD) catheter insertion.

METHODS

This single-center retrospective study included patients who underwent PD catheter insertion under spinal anesthesia in our hospital between January 2016 and December 2020. Patients were divided into the DEX and non-DEX groups according the use of DEX. After 1:1 propensity score matching to adjust for age, sex, body mass index, mean blood pressure (BP), and Charlson comorbidity index, we compared operation-related outcomes, including peak numerical rating scale (NRS), occurrence of nausea, vital signs, or operative time between the two groups.

RESULTS

Of a total of 44 patients, 9 patients received DEX, and 35 did not. After propensity score matching, each group consisted of 8 patients. Peak NRS was significantly lower (P = 0.003) in the DEX group compared with the non-DEX group. Maximum mean BP during the operation was also significantly lower in the DEX group compared with the non-DEX group (P = 0.020), with no significant differences in minimum mean BP between the two groups (P = 0.831). The DEX group showed a trend of shortened operative time (P = 0.068). There were no significant differences in the occurrence of nausea (P = 1.000). Moreover, there was no clinically important adverse event associated with use of DEX.

CONCLUSION

The use of DEX in PD catheter insertion under spinal anesthesia could safely improve operative analgesia.

Environmental and Occupational Considerations of Anesthesia: A Narrative Review and Update

With an estimated worldwide volume of 266 million surgeries in 2015, the call for general inhalation anesthesia is considerable. However, widely used volatile anesthetics such as N2O and the highly fluorinated gases sevoflurane, desflurane, and isoflurane are greenhouse gases, ozone-depleting agents, or both. Because these agents undergo minimal metabolism in the body during clinical use and are primarily (≥95%) eliminated unchanged via exhalation, waste anesthetic gases (WAGs) in operating rooms and postanesthesia care units can pose a challenge for overall elimination and occupational exposure. The chemical properties and global warming impacts of these gases vary, with atmospheric lifetimes of 1-5 years for sevoflurane, 3-6 years for isoflurane, 9-21 years for desflurane, and 114 years for N2O. Additionally, the use of N2O as a carrier gas for the inhalation anesthetics and as a supplement to intravenous (IV) anesthetics further contributes to these impacts. At the same time, unscavenged WAGs can result in chronic occupational exposure of health care workers to potential associated adverse health effects. Few adverse effects associated with WAGs have been documented, however, when workplace exposure limits are implemented. Specific measures that can help reduce occupational exposure and the environmental impact of inhaled anesthetics include efficient ventilation and scavenging systems, regular monitoring of airborne concentrations of waste gases to remain below recommended limits, ensuring that anesthesia equipment is well maintained, avoiding desflurane and N2O if possible, and minimizing fresh gas flow rates (eg, use of low-flow anesthesia). One alternative to volatile anesthetics may be total intravenous anesthesia (TIVA). While TIVA is not associated with the risks of occupational exposure or atmospheric pollution that are inherent to volatile anesthetic gases, clinical considerations should be weighed in the choice of agent. Appropriate procedures for the disposal of IV anesthetics must be followed to minimize any potential for negative environmental effects. Overall, although their contributions are relatively low compared with those of other human-produced substances, inhaled anesthetics are intrinsically potent greenhouse gases and pose a risk to operating-room personnel if not properly managed and scavenged. Factors to reduce waste and minimize the future impact of these substances should be considered.

Pharmaceuticals and the environment

The marked progress and increase in the number of medications available for the treatment of conditions and diseases left a footprint on the surrounding environment. The consumption of medications for human and veterinarian use impact the terrestrial and marine environment and affects the ecosystem. The increase in environmental awareness regarding pharmaceutical related activities led to the development of principles and measures to mitigate a negative environmental impact. Various measures were introduced to promote green manufacturing and practices which led to the development of alternative techniques and processes, which are of benefit to both the environment and the industry. Distributors and pharmacists can contribute through the efficient management of everyday operations which include better stock taking and rotation, grouping deliveries and reducing unused medications. The incorporation of green practices in the pharmacy curriculum empowers future pharmacists with skills and competences required at the place of work to decrease the impact of processes and medicines on the environment. The presence of a pharmacist workforce which is more conscientious about the environment leads to the needed ripple effect to embrace and implement green principles in different pharmacy related settings. Patients should also be educated to avoid hoarding of medications and dispose of medication in a safe and appropriate manner. The implementation of green practices results in a decrease in the use of chemicals and production of waste which in turn leads to a decrease in pollutants which have an impact on climate change.

Measurement of anesthetic pollution in veterinary operating rooms for small animals: Isoflurane pollution in a university veterinary hospital

Introduction

Inhaled anesthetics are used worldwide for anesthesia maintenance both in human and veterinary operating rooms. High concentrations of waste anesthetic gases can lead to health risks for the professionals exposed. Considering that anesthetic pollution in a veterinary surgical center in developing countries is unknown, this study aimed, for the first time, to measure the residual concentration of isoflurane in the air of operating rooms for small animals in a Brazilian university hospital.

Method

Residual isoflurane concentrations were measured by an infrared analyzer at the following sites: corner opposite to anesthesia machine; breathing zones of the surgeon, anesthesiologist, and patient (animal); and in front of the anesthesia machine at three time points, that is, 5, 30 and 120 minutes after anesthesia induction.

Results

Mean residual isoflurane concentrations gradually increased in the corner opposite to anesthesia machine and in the breathing zones of the surgeon and the anesthesiologist (p <  0.05). There was an increase at 30 minutes and 120 minutes when compared to the initial time points in the animal's breathing zone, and in the front of the anesthesia machine (p <  0.05). There was no significant difference at measurement sites regardless of the moment of assessment.

Conclusion

This study reported high residual isoflurane concentrations in veterinary operating rooms without an exhaust system, which exceeds the limit recommended by an international agency. Based on our findings, there is urgent need to implement exhaust systems to reduce anesthetic pollution and decrease occupational exposure.

Environmental sustainability in anaesthesia and critical care

The detrimental health effects of climate change continue to increase. Although health systems respond to this disease burden, healthcare itself pollutes the atmosphere, land, and waterways. We surveyed the 'state of the art' environmental sustainability research in anaesthesia and critical care, addressing why it matters, what is known, and ideas for future work. Focus is placed upon the atmospheric chemistry of the anaesthetic gases, recent work clarifying their relative global warming potentials, and progress in waste anaesthetic gas treatment. Life cycle assessment (LCA; i.e. 'cradle to grave' analysis) is introduced as the definitive method used to compare and contrast ecological footprints of products, processes, and systems. The number of LCAs within medicine has gone from rare to an established body of knowledge in the past decade that can inform doctors of the relative ecological merits of different techniques. LCAs with practical outcomes are explored, such as the carbon footprint of reusable vs single-use anaesthetic devices (e.g. drug trays, laryngoscope blades, and handles), and the carbon footprint of treating an ICU patient with septic shock. Avoid, reduce, reuse, recycle, and reprocess are then explored. Moving beyond routine clinical care, the vital influences that the source of energy (renewables vs fossil fuels) and energy efficiency have in healthcare's ecological footprint are highlighted. Discussion of the integral roles of research translation, education, and advocacy in driving the perioperative and critical care environmental sustainability agenda completes this review.

'Green-gional' anesthesia: the non-polluting benefits of regional anesthesia to decrease greenhouse gases and attenuate climate change

Volatile halogenated gases and nitrous oxide used as part of a balanced general anesthetic may contribute to global warming. By avoiding volatile inhalational agent use, regional anesthesia may reduce greenhouse gas emissions and help prevent global warming. We present a theoretical calculation of the potential benefits and a real-life example of how much regional anesthesia may reduce greenhouse gas emissions.

MOF-Based Adsorbents for Atmospheric Emission Control: A Review

This review focuses on the use of metal–organic frameworks (MOFs) for adsorbing gas species that are known to weaken the thermal self-regulation capacities of Earth’s atmosphere. A large section is dedicated to the adsorption of carbon dioxide, while another section is dedicated to the adsorption of other different gas typologies, whose emissions, for various reasons, represent a “wound” for Earth’s atmosphere. High emphasis is given to MOFs that have moved enough ahead in their development process to be currently considered as potentially usable in “real-world” (i.e., out-of-lab) adsorption processes. As a result, there is strong evidence of a wide gap between laboratory results and the industrial implementation of MOF-based adsorbents. Indeed, when a MOF that performs well in a specific process is commercially available in large quantities, economic observations still make designers tend toward more traditional adsorbents. Moreover, there are cases in which a specific MOF remarkably outperforms the currently employed adsorbents, but it is not industrially produced, thus strongly limiting its possibilities in large-scale use. To overcome such limitations, it is hoped that the chemical industry will be able to provide more and more mass-produced MOFs at increasingly competitive costs in the future.

Is it time to stop using desflurane?

Desflurane has a carbon equivalence 20 times greater than sevoflurane. This article discusses alternative anaesthetic techniques, including sevoflurane, xenon, total intravenous anaesthesia and regional techniques, and methods of reducing venting of gases, which might lower the environmental impact of anaesthesia.

Why be sustainable? The Australian and New Zealand College of Anaesthetists Professional Document PS64: Statement on Environmental Sustainability in Anaesthesia and Pain Medicine Practice and its accompanying background paper

Healthcare’s environmental sustainability is increasingly an area of research and advocacy focus. The Australian and New Zealand College of Anaesthetists (ANZCA) has produced a professional document, PS64, Statement on Environmental Sustainability in Anaesthesia and Pain Medicine Practice, and a background paper, PS64 BP. The purpose of the statement is to affirm ANZCA’s commitment to environmental sustainability and support anaesthetists in promoting environmentally sustainable work practices. This article presents the main features of PS64 and its background paper, and the associated supporting evidence. The healthcare sector is highly interconnected with activities that emit pollution to air, water and soils, considerably adding to humanity’s collective ecological footprint. As anaesthetists, we are uniquely high-carbon doctors due to our work anaesthetising with greenhouse gases (particularly desflurane and nitrous oxide) and our exposure and contribution to large amounts of resource and energy use and waste generation in operating theatres. Discussion is made of the improving research base of anaesthetic life-cycle assessments—that is, cradle-to-grave studies of how much energy, water and so on a product or process requires throughout its entire life. Thereafter, reducing, reusing and recycling as well as water use are examined. Ongoing research efforts within environmentally sustainable anaesthesia are highlighted. Environmentally sustainable anaesthesia requires scholarship, health advocacy, leadership, communication and collaboration. The focus is placed on practical initiatives within PS64 and the background paper that can be achieved by all anaesthetists striving towards more sustainable healthcare practices that reduce waste, reap financial benefits and improve health.

An insight into clustering of halogenated anesthetics molecules in metal-organic frameworks: Evidence of adsorbate self-association in micropores

In order to better understand the adsorption of volatile halogenated anesthetics on metal organic frameworks (MOFs), sevoflurane vapor adsorption experiments were performed on commercial MOF-177 at different temperatures. Due to the surface homogeneity of such an adsorbent, arising from its almost unimodal pore size distribution and the absence of specific, coordinatively unsaturated adsorption active sites, sevoflurane adsorption isotherms exhibited a peculiar deviation from the Langmuirian behavior. Consequently, they show a "kink" at a specific pressure that increases with increasing equilibrium temperature. Successful modeling of such data by means of the Talu-Meunier equation confirmed clustering of adsorbate molecules inside adsorbent micropores, similarly to water vapor adsorption on activated carbon, which may play an important role when designing a system using MOFs as the potential adsorbents for capturing anesthetics.

European Society of Anaesthesiology Task Force on Nitrous Oxide: a narrative review of its role in clinical practice

Nitrous oxide (N₂O) is one of the oldest drugs still in use in medicine. Despite its superior pharmacokinetic properties, controversy remains over its continued use in clinical practice, reflecting in part significant improvements in the pharmacology of other anaesthetic agents and developing awareness of its shortcomings. This narrative review describes current knowledge regarding the clinical use of N₂O based on a systematic and critical analysis of the available scientific literature. The pharmacological properties of N₂O are reviewed in detail along with current evidence for the indications and contraindications of this drug in specific settings, both in perioperative care and in procedural sedation. Novel potential applications for N₂O for the prevention or treatment of chronic pain and depression are also discussed. In view of the available evidence, we recommend that the supply of N₂O in hospitals be maintained while encouraging its economic delivery using modern low flow delivery systems. Future research into its potential novel applications in prevention or treatment of chronic conditions should be pursued to better identify its role place in the developing era of precision medicine.

Waste anesthetic gas exposure and strategies for solution

As inhaled anesthetics are widely used, medical staff have inevitably suffered from exposure to anesthetic waste gases (WAGs). Whether chronic exposure to WAGs has an impact on the health of medical staff has long been a common concern, but conclusions are not consistent. Many measures and equipment have been proposed to reduce the concentration of WAGs as far as possible. This review aims to dissect the current exposure to WAGs and its influence on medical staff in the workplace and the environment, and summarize strategies to reduce WAGs.

Occupational hazards, DNA damage, and oxidative stress on exposure to waste anesthetic gases

Background and objectives

The waste anesthetic gases (WAGs) present in the ambient air of operating rooms (OR), are associated with various occupational hazards. This paper intends to discuss occupational exposure to WAGs and its impact on exposed professionals, with emphasis on genetic damage and oxidative stress.

Content

Despite the emergence of safer inhaled anesthetics, occupational exposure to WAGs remains a current concern. Factors related to anesthetic techniques and anesthesia workstations, in addition to the absence of a scavenging system in the OR, contribute to anesthetic pollution. In order to minimize the health risks of exposed professionals, several countries have recommended legislation with maximum exposure limits. However, developing countries still require measurement of WAGs and regulation for occupational exposure to WAGs. WAGs are capable of inducing damage to the genetic material, such as DNA damage assessed using the comet assay and increased frequency of micronucleus in professionals with long-term exposure. Oxidative stress is also associated with WAGs exposure, as it induces lipid peroxidation, oxidative damage in DNA, and impairment of the antioxidant defense system in exposed professionals.

Conclusions

The occupational hazards related to WAGs including genotoxicity, mutagenicity and oxidative stress, stand as a public health issue and must be acknowledged by exposed personnel and responsible authorities, especially in developing countries. Thus, it is urgent to stablish maximum safe limits of concentration of WAGs in ORs and educational practices and protocols for exposed professionals.

Economic Evaluation of Pharmacologic Pre- and Postconditioning With Sevoflurane Compared With Total Intravenous Anesthesia in Liver Surgery: A Cost Analysis

BACKGROUND

Pharmacologic pre- and postconditioning with sevoflurane compared with total IV anesthesia in patients undergoing liver surgery reduced complication rates as shown in 2 recent randomized controlled trials. However, the potential health economic consequences of these different anesthesia regimens have not yet been assessed.

METHODS

An expostcost analysis of these 2 trials in 129 patients treated between 2006 and 2010 was performed. We analyzed direct medical costs for in-hospital stay and compared pharmacologic pre- and postconditioning with sevoflurane (intervention) with total IV anesthesia (control) from the perspective of a Swiss university hospital. Year 2015 costs, converted to US dollars, were derived from hospital cost accounting data and compared with a multivariable regression analysis adjusting for relevant covariables. Costs with negative prefix indicate savings and costs with positive prefix represent higher spending in our analysis.

RESULTS

Treatment-related costs per patient showed a nonsignificant change by -12,697 US dollars (95% confidence interval [CI], 10,956 to -36,352; P = .29) with preconditioning and by -6139 US dollars (95% CI, 6723 to -19,000; P = .35) with postconditioning compared with the control group. Results were robust in our sensitivity analysis. For both procedures (control and intervention) together, major complications led to a significant increase in costs by 86,018 US dollars (95% CI, 13,839-158,198; P = .02) per patient compared with patients with no major complications.

CONCLUSIONS

In this cost analysis, reduced in-hospital costs by pharmacologic conditioning with sevoflurane in patients undergoing liver surgery are suggested. This possible difference in costs compared with total IV anesthesia is the result of reduced complication rates with pharmacologic conditioning, because major complications have significant cost implications.

Tunable Porous Coordination Polymers for the Capture, Recovery and Storage of Inhalation Anesthetics

The uptake of inhalation anesthetics by three topologically identical frameworks is described. The 3D network materials, which possess square channels of different dimensions, are formed from the relatively simple combination of Zn^II centres and dianionic ligands that contain a phenolate and a carboxylate group at opposite ends. All three framework materials are able to adsorb N₂ O, Xe and isoflurane. Whereas the framework with the widest channels is able to adsorb large quantities of the various guests from the gas phase, the frameworks with the narrower channels have superior binding enthalpies and exhibit higher levels of retention. The use of ligands in which substituents are bound to the aromatic rings of the bridging ligands offers great scope for tuning the adsorption properties of the framework materials.

Breath gas concentrations mirror exposure to sevoflurane and isopropyl alcohol in hospital environments in non-occupational conditions

Anaesthetic gases and disinfectants are a primary source of air contamination in hospitals. A highly sensitive sorbent-trap methodology has been used to analyse exhaled breath samples with detection limits in the pptv range, which allows volatile organic compounds (VOCs) to be detected at significantly lower levels (5-6 orders of magnitude below) than the recommended exposure limits by different organizations. Two common VOCs used in hospital environments, isopropyl alcohol (IPA) and sevoflurane, have been evaluated. Forced-expiratory breath samples were obtained from 100 volunteers (24 hospital staff, 45 hospital visitors and 31 external controls). Significant differences for IPA were found between samples from volunteers who had not been in contact with hospital environments (mean value of 8.032 ppbv) and people staying (20.981 ppbv, p  =  0.0002) or working (19.457 ppbv, p  =  0.000 09) in such an environment. Sevoflurane, an anaesthetic gas routinely used as an inhaled anaesthetic, was detected in all samples from volunteers in the hospital environment but not in volunteers who had not been in recent contact with a hospital environment. The levels of sevoflurane were significantly higher (p  =  0.000 24) among staff members (0.522 ppbv) than among visitors to the hospital (0.196 ppbv). We conclude that highly sensitive methods are required to detect anaesthetic gas contamination in hospital environments.

How green is my operation theater?

OBJECTIVE

To ascertain the awareness regarding global warming and the anesthesia practices contributing to it in the city of Delhi.

MATERIALS AND METHODS

A questionnaire was circulated amongst the qualified anesthesiologists (consultants and senior residents) in the city of Delhi. The initial contact was made through e-mail and the questionnaire was required to be filled and returned electronically. The questionnaire was also made available online at http://sites.google.com/site/surveydelhi. After 1 month, the forms were distributed physically. Assuming that at least 50% of the approximately 1200 practising anesthesiologists would be able to recognize the greenhouse gases correctly, the target number of responses was 150 with 99% confidence limit.

RESULTS

Of the 831 anesthesiologists contacted, only 184 responded. Ninety-eight percent were aware of the greenhouse effect, but only 15.8% (29) could correctly identify all the greenhouse gases. However, 47.28% (87) could identify nitrous oxide and inhalational agents as a cause of greenhouse effect. Ninety percent of the respondents use circle system and 87% use low flows frequently. Ninety-three percent (171) of respondents routinely use nitrous oxide, and 32.1% (59) would, however, not use air even if made available. Seventy-nine percent (145) advocated total intravenous anesthesia as an alternative to reduce the menace.

CONCLUSION

Only 22% were motivated enough to respond to the survey. More than half of these anesthesiologists were not aware about the anesthetic agents contributing to the greenhouse effect. However, their clinical practices inadvertently do not add to the environmental pollution.

[Impact of the decrease of nitrous oxide use on the consumption of halogenated agents]

OBJECTIVE

Nitrous oxide (N2O) toxicity and its impact on pollution lead to restrict its use. A decrease of N2O consumption should increase the hypnotic inhaled consumption. This monocentric study estimated consumptions and costs of halogenated agents (HA) and N2O over 5 years when the N2O consumption was reduced.

STUDY DESIGN

Retrospective from a computerized database.

PATIENTS

Between 2006 and 2010, 34,097 procedures were studied after two meetings exposing the risks of the N2O.

METHODS

At the end of anesthesia, consumptions of hypnotic agents (millilitres transmitted by the injectors and the blender) were archived in the database. The annual consumption of agents was obtained by adding the individual consumptions, then divided by the annual number of cases. The costs were given by the hospital pharmacy from invoices.

RESULTS

N2O consumption per anesthesia constantly decreased during the study, from 75.1L by act to 22.7L. The sum of the annual consumptions of N2O and air did not change suggesting that total fresh gas flow remained stable. Between 2006 and 2010, the sevoflurane consumption by act increased by 25%, from 16.5 to 20.6mL, and desflurane consumption by 37%, from 46.1 to 63.1mL by patient. The costs of the administration of hypnotic agents remained stable.

CONCLUSION

N2O consumption decrease had an impact on the consumption of HA. The cost reduction of the N2O was counterbalanced by the increase of halogenated vapor cost. The profit of the ecological impact of the reduction in N2O use could be quantified.

Nitrous oxide: are we still in equipoise? A qualitative review of current controversies

This review considers the current position of nitrous oxide in anaesthetic practice and balances potential beneficial and disadvantageous effects. The classic adverse characteristics of nitrous oxide, such as diffusion hypoxia, expansion of gas-filled spaces, and postoperative nausea and vomiting, are often cited as reasons to avoid this old drug. Recent concerns regarding neurotoxicity, adverse cardiovascular outcomes, and wound complications have further hardened many practitioners against nitrous oxide. New evidence and underpinning mechanistic data, however, suggest potential beneficial effects on the central nervous system, cardiovascular system, and acute and chronic pain. While we await the outcome of large studies including ENIGMA-II, many clinicians have already decided against this agent. The authors argue that this abandonment may be premature. Clinical Trial Registration None required.

Brief review: theory and practice of minimal fresh gas flow anesthesia

PURPOSE

The aim of this brief review is to provide an update on the theory regarding minimal fresh gas flow techniques for inhaled general anesthesia. The article also includes an update and discussion of the practical aspects associated with minimal-flow anesthesia, including the advantages, potential limitations, and safety considerations of this important anesthetic technique.

PRINCIPAL FINDINGS

Reducing the fresh gas flow to < 1 L·min(-1) during maintenance of anesthesia is associated with several benefits. Enhanced preservation of temperature and humidity, cost savings through more efficient utilization of inhaled anesthetics, and environmental considerations are three key reasons to implement minimal-flow and closed-circuit anesthesia, although potential risks are hypoxic gas mixtures and inadequate depth of anesthesia. The basic elements of the related pharmacology need to be considered, especially pharmacokinetics of the inhaled anesthetics. The third-generation inhaled anesthetics, sevoflurane and desflurane, have low blood and low tissue solubility, which facilitates rapid equilibration between the alveolar and effect site (brain) concentrations and makes them ideally suited for low-flow techniques. The use of modern anesthetic machines designed for minimal-flow techniques, leak-free circle systems, highly efficient CO(2) absorbers, and the common practice of utilizing on-line real-time multi-gas monitor, including essential alarm systems, allow for safe and cost-effective minimal-flow techniques during maintenance of anesthesia. The introduction of new anesthetic machines with built-in closed-loop algorithms for the automatic control of inspired oxygen and end-tidal anesthetic concentration will further enhance the feasibility of minimal-flow techniques.

CONCLUSIONS

With our modern anesthesia machines, reducing the fresh gas flow of oxygen to 0.3-0.5 L·min(-1) and using third-generation inhaled anesthetics provide a reassuringly safe anesthetic technique. This environmentally friendly practice can easily be implemented for elective anesthesia; furthermore, it will facilitate cost savings and improve temperature homeostasis.

Medical intelligence article: assessing the impact on global climate from general anesthetic gases

Although present in the atmosphere with a combined concentration approximately 100,000 times lower than carbon dioxide (i.e., the principal anthropogenic driver of climate change), halogenated organic compounds are responsible for a warming effect of approximately 10% to 15% of the total anthropogenic radiative forcing of climate, as measured relative to the start of the industrial era (approximately 1750). The family of anesthetic gases includes several halogenated organic compounds that are strong greenhouse gases. In this short report, we provide an overview of the state of knowledge regarding the impact of anesthetic gas release on the environment, with particular focus on its contribution to the radiative forcing of climate change.