Anesthetic gases and global warming: Potentials, prevention and future of anesthesia

Should pipeline nitrous oxide be discontinued in secondary care: A cost-benefit analysis

Background

Nitrous oxide (N2O) has seen a marked decline in its usage in recent years due to its adverse clinical effects. We audited the practice in our department to evaluate the N2O consumption and cost-effectiveness of its supply.

Methodology

Electronic anesthesia records of all patients anesthetized in our main operating rooms in a typical month were reviewed retrospectively, and utilization of N2O was noted in addition to the patient demographics, surgical procedure, and specialty.

Results

A total of 950 patients were anesthetized, and 3.1% received N2O. The annual usage was estimated to be 72,871 liters, with a leakage of 3,883,105 liters to the environment, posing a safety hazard and wasting 149,612.50 SAR.

Conclusion

Notable costs and environmental benefits may be achieved by substituting a piped supply of N2O with portable E-cylinders on demand in operating rooms for rational use.

Paving the way to environment-friendly greener anesthesia

Health-care settings have an important responsibility toward environmental health and safety. The operating room is a major source of environmental pollution within a hospital. Inhalational agents and nitrous oxide are the commonly used gases during general anesthesia for surgeries, especially in the developing world. These greenhouse gases contribute adversely to the environmental health both inside the operating room and in the outside atmosphere. Impact of these anesthetic agents depends on the total consumption, characteristics of individual agents, and gas flows, with higher levels increasing the environmental adverse effects. The inimical impact of nitrous oxide is higher due to its longer atmospheric half-life and potential for destruction of the ozone layer. Anesthesiologist of today has a choice in the selection of anesthetic agents. Prudent decisions will help in mitigating environmental pollution and contributing positively to a greener planet. Therefore, a shift from inhalational to intravenous-based technique will reduce the carbon footprint of anesthetic agents and their impact on global climate. Propofol forms the mainstay of intravenous anesthesia technique and is a proven drug for anesthetic induction and maintenance. Anesthesiologists should appreciate growing concerns about the role of inhalational anesthetics on the environment and join the cause of environmental responsibility. In this narrative review, we revisit the pharmacological and pharmacokinetic considerations, clinical uses, and discuss the merits of propofol-based intravenous anesthesia over inhalational anesthesia in terms of environmental effects. Increased awareness about the environmental impact and adoption of newer, versatile, and user-friendly modalities of intravenous anesthesia administration will pave the way for greener anesthesia practice.

Noncovalent chemistry of xenon opens the door for anesthetic xenon recovery using Bio-MOFs

Designing an inexpensive and highly efficient recovery process for xenon (Xe) is gaining importance in the development of sustainable applications. Using metal organic frameworks (MOFs) for separating Xe from anesthetic gas mixtures has been a recent topic studied rarely and superficially in the literature. We theoretically investigated Xe recovery performances of 43 biological MOFs (Bio-MOFs) formed by biocompatible metal cations and biological endogenous linkers. Xe uptakes and Xe permeabilities in its binary mixtures with CO2, O2, and N2 were investigated by applying Grand Canonical Monte Carlo and Molecular Dynamics simulations. Materials with metalloporphyrin, hexacarboxylate, triazine, or pyrazole ligands, dimetallic paddlewheel units, relatively large pore sizes (PLD > 5 Å and LCD > 10 Å), large void fractions (≈0.8), and large surface areas (>2900 m2 g-1) have been determined as top performing Bio-MOFs for Xe recovery. By applying Density Functional Theory simulations and generating electron density difference maps, we determined that Xe-host interactions in the top performing Bio-MOFs are maximized mainly due to noncovalent interactions of Xe, such as charge-induced dipole and aerogen-π interactions. Polarized Xe atoms in the vicinity of cations/anions as well as π systems are fingerprints of enhanced guest-host interactions. Our results show examples of rarely studied aerogen interactions that play a critical role in selective adsorption of Xe in nanoporous materials.

Environmental and Economic Impact of Using a Higher Efficiency Ventilator and Vaporizer During Surgery Under General Anesthesia: A Randomized Controlled Prospective Cohort

Background Compared to traditional breathing circuits, low-volume anesthesia machines utilize a lower-volume breathing circuit paired with needle injection vaporizers that supply volatile agents into the circuit mainly during inspiration. We aimed to assess whether or not low-volume anesthesia machines, such as the Maquet Flow-i C20 anesthesia workstation (MQ), deliver volatile anesthetics more efficiently than traditional anesthesia machines, such as the GE Aisys CS² anesthesia machine (GE), and, secondarily, whether this was in a meaningful economic or environmentally conscious way. Methodology Participants enrolled in the study (Institutional Review Board Identifier: 2014-1248) met the following inclusion criteria: 18-65 years old, scheduled for surgery requiring general anesthesia at the University of California Irvine Health, and expected to receive sevoflurane for the duration of the procedure. Exclusion criteria included age <18 years old, a history of chronic obstructive pulmonary disorder, cardiovascular disease, sevoflurane sensitivity, body mass index >30 kg/m², American Society of Anesthesiologists >2, pregnancy, or surgery scheduled <120 minutes. We calculated the total amount of sevoflurane delivered and consumption rates during induction and maintenance periods and compared the groups using one-sided parametric testing (Student's t-test). There was no suspicion that the low-volume circuit could use more sevoflurane and that the outcome did not answer our research question. One-sided testing allowed for more power to be more certain of smaller differences in our results. Results In total, 103 subjects (MQ: n = 52, GE: n = 51) were analyzed. Seven subjects were lost to attrition of different types. Overall, the MQ group consumed significantly less sevoflurane (95.5 ± 49.3 g) compared to the GE group (118.3 ± 62.4 g) (p = 0.043), corresponding to an approximately 20% efficiency improvement in overall agent delivery. When accounting for the fresh gas flow setting, agent concentration, and length of induction, the MQ delivered the volatile agent at a significantly lower rate compared to the GE (7.4 ± 3.2 L/minute vs. 9.1 ± 4.1 L/minute; p = 0.017). Based on these results, we estimate that the MQ can save an estimated average of $239,440 over the expected 10-year machine lifespan. This 20% decrease in CO₂ equivalent emissions corresponds to 201 metric tons less greenhouse gas emissions over a decade compared to the GE, which is equivalent to 491,760 miles driven by an average passenger vehicle or 219,881 pounds of coal burned. Conclusions Overall, our results from this study suggest that the MQ delivers statistically significantly less (~20%) volatile agent during routine elective surgery using a standardized anesthetic protocol and inclusion/exclusion criteria designed to minimize any patient or provider heterogeneity effects on the results. The results demonstrate an opportunity for economic and environmental benefits.

Approaches to Greening Radiology

The health care sector is a resource-intensive industry, consuming significant amounts of water and energy, and producing a multitude of waste. Health care providers are increasingly implementing strategies to reduce energy use and waste. Little is currently known about existing sustainability strategies and how they may be supported by radiology practices. Here, we review concepts and ideas that minimize energy use and waste, and that can be supported or implemented by radiologists.

The Environmental Impact of Open Versus Endoscopic Carpal Tunnel Release

PURPOSE

The environmental impact of common ambulatory hand surgeries has been an area of growing interest in recent years. There were 2 objectives of this study: (1) to quantify the carbon footprint of carpal tunnel surgery and its principal driving components; and (2) to compare the carbon footprints of open carpal tunnel release (oCTR) and endoscopic carpal tunnel release (eCTR).

METHODS

We performed a life cycle assessment to quantify the environmental impacts of 2 surgical procedures: oCTR and eCTR. Patients were retrospectively identified by querying the Mass General Brigham institutional billing database. Fourteen oCTR procedures and 14 eCTR procedures in 28 patients were included in the life cycle assessment. The boundaries of the life cycle assessment were the start and end times of the procedures. The environmental impacts were estimated using the carbon footprint, expressed in the equivalent mass of carbon dioxide released into the atmosphere (kgCO₂-eq). The facility-related, processing-related, solid waste-related, and total kgCO₂-eq were calculated.

RESULTS

The average carbon footprint of carpal tunnel release was 83.1 kgCO₂-eq and was dominated by processing-related and facilities-related factors. The average carbon footprint of eCTR (106.5 kgCO₂-eq) was significantly greater than that of oCTR (59.6 kgCO₂-eq).

CONCLUSIONS

Endoscopic carpal tunnel release leaves a greater carbon footprint than oCTR, and its environmental impact is dominated by facility-related and central processing-related factors.

TYPE OF STUDY/LEVEL OF EVIDENCE

Economic and Decision Analyses IV.

Effects of Cisatracurium in Sevoflurane and Propofol Requirements in Dog-Undergoing-Mastectomy Surgery

The purpose of the present study was to test whether the addition of cisatracurium in combination with propofol and sevoflurane would result in a change in doses of used anesthetic drugs. Ten dogs (Group A) undergoing elective unilateral mastectomy surgery were included in the study. To induce and maintain anesthesia, subjects received propofol and sevoflurane at varying doses; analgesia was performed with remifentanil. After three months, the same subjects (Group B) underwent contralateral mastectomy and received the same anesthetic protocol with the addition of cisatracurium at a dosage of 0.2 mg/kg−1. The following parameters were monitored during anesthesia: heart rate, systolic blood pressure, end-tidal CO2, oxygen saturation, halogenate requirement, and rectal temperature at baseline (T0), induction (T1), 5 (T5), 10 (T10), 15 (T15), 20 (T20), 25 (T25), 30 (T30), and 35 (T35) time points. In Group A, halogenate requirement was reduced at all the time points other than T1 (p < 0.001); in Group B, the percentage of halogenate requirement was already reduced at T1 and remained constant during the experimental period, showing no significant intragroup differences. The dose requirements of sevoflurane and propofol varied significantly between the two groups, with significantly lower dosages in the Group B (the cisatracurium-treated group). Moreover, patients treated with cisatracurium showed a stable anesthetic plan. The nondepolarizing-muscle-relaxant cisatracurium besylate could be considered a useful adjunct to anesthetic protocols.

Environmental Sustainability in the Orthopaedic Operating Room

Hotter global temperatures and increasingly variable climate patterns negatively affect human health, with a wide recognition that climate change is a major global health threat. Human activities, including those conducted in the orthopaedic operating room (OR), contribute to climate change by generating greenhouse gases that trap infrared radiation from the earth's surface. This review provides an overview of the environmental effect of the orthopaedic OR and efforts to address environmental sustainability in the OR. These concepts are presented with a particular focus on patient safety and cost savings because roll-out of these efforts must be conducted with a pragmatic and patient-centered focus. Orthopaedic surgeons have an opportunity to lead efforts to improve environmental sustainability in the OR and thus contribute to efforts to curb climate 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.

Cardiac surgery and the sustainable development goals: a review

Background

In 2015, the United Nations adopted the Sustainable Development Goals (SDGs) as key priorities to improve the global health and international development agenda in an intersectoral manner, highlighting 17 SDGs. Six billion people lack access to safe, timely, and affordable cardiac surgical care due to capacity, geographic, and financial barriers. Nevertheless, cardiac surgery is largely disregarded on the global health agenda. In this review, we explore the intersection between cardiac surgery and the SDGs to delineate potential policy and advocacy avenues for the cardiothoracic surgical community.

Main body

A narrative review was performed using the PubMed/MEDLINE, Scopus, and WHO databases with variations of the search terms “cardiac surgery,” “cardiovascular diseases,” and keywords extracted from individual SDGs. All SDGs were manually reviewed to define intersectionality with global cardiac surgery. Out of 17 SDGs, 15 are relevant and require additional attention from the cardiovascular community. SDG3, “Good Health and Well-being,” is the most relevant, although the intersection between global cardiac surgery and other SDGs is apparent. A call for interdisciplinary collaboration through increased preventive mechanisms, rigorous, all-inclusive clinical trials, advocacy with relevant legislators, and mobilizing capacity building mechanisms are made.

Conclusion

Meeting the SDGs will require recognition of cardiovascular disease management, including cardiac surgical care. Cardiac surgeons are essential stakeholders of multidisciplinary collaborations working to improve access to safe, timely, and affordable cardiac surgery for all. Their role as advocates will be vital to establish local, national, regional, and international partnerships and to ensure progress towards SDG attainment.

Sustainability Initiatives in the Operating Room

BACKGROUND

Operating rooms (ORs) contribute up to 30% of a hospital's waste, are very resource-intensive, and thus provide an opportunity for improvement.

METHODS

A narrative review was conducted, searching MEDLINE, EMBASE, and ProQuest databases. The study included 78 of the 108 published articles.

RESULTS

The researchers identified and categorized articles according to the following major themes: Committee and Leadership; Waste Reduction; Segregating OR waste; Minimizing unnecessary devices and packaging; Reducing energy consumption; Choosing anesthetic gases; Education; Reducing water consumption; Different surgical venues; Donating medical supplies. Formation of an OR committee or a hospital Green Team dedicated to environmentally sustainable initiatives can significantly improve health care's impact on the environment while saving money. Changes in supply chain with preferences for reusable devices, effective recycling, repurposing instruments, and donating items can all be effective means of diverting waste away from landfills. Reducing unnecessary packaging and instruments would eliminate excess in the waste stream. Curtailing energy and water usage results in cost and environmental savings. Surgical venue (inpatient vs. outpatient surgical center) can also contribute to waste. Transitioning away from certain inhaled anesthetics can minimize greenhouse gas impact. Education to all levels in the health care system is important to drive change and maintain change.

CONCLUSION

Optimizing efficiency and decreasing waste generation can have a positive impact on the environment and can be accompanied by cost reduction. Because the field of sustainability in health care is young but burgeoning, increased research is needed to support evidence-based approaches.

Comparison of Propofol-Dexmedetomidine-Based Intravenous and Sevoflurane-Based Inhalational Anesthesia in Patients Undergoing Modified Radical Mastectomy

Background and Aim:

Total intravenous anesthesia (TIVA) has proven advantage over inhalational anesthesia in terms of stable hemodynamic, eco-friendly, and good recovery profile, but apprehension regarding adequate depth of anesthesia and intraoperative recall is still pertaining. This study aims to compare propofol–dexmedetomidine-based TIVA with sevoflurane-based inhalational anesthesia in modified radical mastectomy in terms of depth of anesthesia, intraoperative recall, recovery profile, and hemodynamic status.

Settings and Design:

This prospective randomized controlled study was conducted at a tertiary care center over a time frame of 1 year.

Methodology:

In this randomized controlled study, 100 patients were randomly distributed into two groups: TIVA (Group T) and inhalational anesthesia (Group I). Group T patients received injection dexmedetomidine: 1 μg.kg⁻¹ over 10 min followed by 0.7 μg.kg⁻¹.h⁻¹ and injection propofol: 25–100 μg.kg⁻¹.min⁻¹. Ventilation was maintained with oxygen–air gas flow. In Group I, patients were ventilated with nitrous oxide–oxygen (50:50) and sevoflurane. Rest of anesthesia for both the groups was same. Primary objective was to achieve adequate depth of anesthesia as monitored by intraoperative bispectral index value (BIS, 40–60). Hemodynamic variables, recovery profile, and amount of individual anesthetic agent consumed were recorded for comparison between two groups. For comparison of scale variables between two groups, independent sample t-test for significant difference between two sample means has been followed.

Results:

Intraoperative BIS and hemodynamic variables were comparable (P > 0.05). Emergence time was 5.10 min in the TIVA group versus 8.38 min in the inhalational group (P = 0.00). Modified Aldrete score was comparable in two groups (P > 0.05). Cost of TIVA agents consumed per patient was 40% lesser than inhalational agents.

Conclusion:

TIVA maintains adequate depth of anesthesia along with stable hemodynamic and good recovery profile, at low cost in an eco-friendly manner.

Empowering Surgeons, Anesthesiologists, and Obstetricians to Incorporate Environmental Sustainability in the Operating Room

OBJECTIVE

We review the existing research on environmentally sustainable surgical practices to enable SAO to advocate for improved environmental sustainability in operating rooms across the country.

SUMMARY OF BACKGROUND DATA

Climate change refers to the impact of greenhouse gases emitted as a byproduct of human activities, trapped within our atmosphere and resulting in hotter and more variable climate patterns.1 As of 2013, the US healthcare industry was responsible for 9.8% of the country's emissions2; if it were itself a nation, US healthcare would rank 13th globally in emissions.3 As one of the most energy-intensive and wasteful areas of the hospital, ORs drive this trend. ORs are 3 to 6 times more energy intensive than clinical wards.4 Further, ORs and labor/delivery suites produce 50%-70% of waste across the hospital.5,6 Due to the adverse health impacts of climate change, the Lancet Climate Change Commission (2009) declared climate change "the biggest global health threat of the 21st century" and predicted it would exacerbate existing health disparities for minority groups, children and low socioeconomic patients.7.

METHODS/RESULTS

We provide a comprehensive narrative review of published efforts to improve environmental sustainability in the OR while simultaneously achieving cost-savings, and highlight resources for clinicians interested in pursuing this work.

CONCLUSION

Climate change adversely impacts patient health, and disproportionately impacts the most vulnerable patients. SAO contribute to the problem through their resource-intensive work in the OR and are uniquely positioned to lead efforts to improve the environmental sustainability of the OR.

Simple Green Changes for Anesthesia Practices to Make a Difference

The environmental debate on going green in the operating room (OR) has been a controversial topic for many years. Challengers of greening efforts cite various obstacles and arguments against these initiatives. However, ORs in the United States continue to generate a staggering amount of waste daily. In this article, we review major barriers to going green and highlight simple, yet effective greening strategies that anesthesia practices could adopt to reduce our carbon footprint.

'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.

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.

Environmental sustainability in veterinary anaesthesia

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.

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.

Environment-Friendly Practices in Operating Rooms in Turkey

BACKGROUND

Environment-friendly practices refer to decreasing energy consumption, using resources carefully and sustainably, and reducing environmental pollution. An environment-friendly hospital is defined as a hospital where energy is saved, carbon emissions are decreased, and productivity and quality are increased. Operating rooms (ORs) account for most wastes generated daily by hospitals. Thus, adopting environment-friendly healthcare practices in ORs will have a positive impact on the environment.

PURPOSE

The aim of this study was to identify and recommend environment-friendly practices that are feasible for implementation in ORs in Turkey.

METHODS

Data on the environment-friendly practices that are currently being practiced in the ORs of hospitals in Izmir Province were collected using face-to-face interviews with nurses who were in charge of ORs in Izmir Province. The interviews were conducted using an OR identification form and Greening the OR Checklist. The study population included all of the hospitals in Izmir Province, and the study sample included 18 ORs in the 11 hospitals that consented to take part in the research. Permission to conduct this research was obtained from the ethics committee of the nursing school as well as from the participating hospitals where the study was conducted.

RESULTS

The hospitals included in the study had, on average, 7.44 ± 7.32 ORs, each of which employed an average of 16.83 ± 17.16 nurses. Four fifths (83.3%) of the ORs always monitored their wastes, and 88.9% gave their batteries to recyclers. In addition, 72.2% renewed their surgical sets to reduce excessive use of materials, and 72.2% preferred using reusable materials instead of single-use materials in their surgical sets. However, 66.7% of the ORs had no environmental team, 93% did not use an environmentally safe surface cleaner, 83.3% did not use sensor controls on lights, and 66.7% did not use LED lights.

CONCLUSIONS

Although most hospitals did not have a special team to recommend and enforce environment-friendly procedures, the OR nurses did their best to protect the environment.

Analytical Determination of Medical Gases Consumption and Their Impact on Hospital Sustainability

Medical gases are known to show a great environmental impact and also to consume relevant resources in terms of hospital management. The present work reports on a study performed between 2008 and 2016 in a target set of 12 Spanish hospitals with floor area and number of beds ranging 2314–23,300 m2 and 20–194, respectively, for which the average annual consumption rates of oxygen, nitrogen, medicinal air, carbon dioxide and nitrogen protoxide were analysed. The annual consumption of medical gases in a hospital was proved to be correlated with the number of hospital discharges, the number of surgeries, the number of emergency interventions, the number of hospitalisations, the number of hospital beds, the useful floor area of the building and the number of workers. In particular, the annual consumption per hospital bed was computed as 350 m3 for oxygen, 325 m3 for medicinal air, 9 m3 for nitrogen protoxide and 3 m3 for carbon dioxide. It is shown that healthcare activity appears as an adequate variable to quantify and to monitor medical gases consumption in hospitals, to assess the size of their facilities as well as to optimise maintenance management.

A randomized controlled trial comparing the myocardial protective effects of isoflurane with propofol in patients undergoing elective coronary artery bypass surgery on cardiopulmonary bypass, assessed by changes in N-terminal brain natriuretic peptide

Objective:

The objective of the study is to compare the myocardial protective effects of isoflurane with propofol in patients undergoing elective coronary artery bypass surgery on cardiopulmonary bypass (CPB), the cardio protection been assessed by changes in N-terminal brain natriuretic peptide (NT proBNP).

Methodology and Design:

This study is designed as a participant blinded, prospective randomized clinical trial.

Setting:

Christian Medical College Hospital, Vellore, India.

Participants:

Patients undergoing elective coronary artery bypass surgery on CPB.

Intervention:

Anesthesia was maintained with 0.8–1.2 end tidal concentrations of isoflurane in the isoflurane group and in the propofol group, anesthesia was maintained with propofol infusion as described by Roberts et al.

Measurements:

Hemodynamic data were recorded at frequent intervals during the surgery and up to 24 h in the Intensive Care Unit (ICU). The other variables that were measured include duration of mechanical ventilation, dose and duration of inotropes in ICU, (inotrope score), duration of ICU stay, NT proBNP levels before induction and 24 h postoperatively, creatine kinase-MB levels in the immediate postoperative, first and second day.

Results:

Mean heart rate was significantly higher in propofol group during sternotomy, (P = 0.021). Propofol group had a significantly more number of patients requiring nitroglycerine in the prebypass period (P = 0.01). The increase in NT proBNP from preoperative to postoperative value was lesser in the isoflurane group compared to propofol even though the difference was not statistically significant. The requirement of phenylephrine to maintain mean arterial pressure within 20% of baseline, mechanical ventilation duration, inotrope use, duration of ICU stay and hospital stay were found to be similar in both groups.

Conclusion:

Propofol exhibit comparable myocardial protective effect like that of isoflurane in patients undergoing coronary artery bypass graft surgery. Considering the unproven mortality benefit of isoflurane and the improved awareness of green OT concept, propofol may be the ideal alternative to volatile anesthetics, at least in patients with good left ventricular function.

Adsorbent comparisons for anesthetic gas capture in hospital air emissions

For the development of emission control strategies, activated carbon, zeolite, molecular sieves, and a silica gel were tested for adsorption of the newer anesthetic gases isoflurane, sevoflurane, and desflurane from air. The activated carbon Norit GCA 48 was selected for the best performance, and adsorption isotherms at room temperature were developed for the three anesthetics. Equilibrium capacities for this carbon were in the range of 500 to 1,000 mg g(-1) for these anesthetics at partial pressures ranging from 5 to 45 Torr, with the most volatile compound (desflurane) showing the least favorable adsorption. Activated carbons are therefore suggested for use as effective adsorbents in emission control of these anesthetic gases from hospitals.