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Hydrogen refueling stations (HRS) operating at high pressures pose a higher risk of leakage than conventional gas stations. Therefore, in this study, a quantitative risk assessment (QRA) was conducted using DNV-GL SAFETI v.8.9. The impact of the shutoff valve was quantitatively assessed, and step-by-step mitigation was applied to propose the minimum installation requirements for the valve necessary to achieve broadly acceptable risk levels. The QRA includes sequence analysis (CA), individual risk (IR), and societal risk (SR), with accident scenarios consisting of catastrophic ruptures and three leak scenarios. The research results indicate that the application of a dual shutoff valve system resulted in an IR of 7.48 × 10−5, effectively controlling the risk below the as low as reasonably practicable (ALARP) criteria of the Health and Safety Executive (HSE). The SR was analyzed based on the ALARP criteria in the Netherlands, and the application of the dual shutoff valve system effectively controlled the risk below the ALARP criteria. Consequently, this study suggests that applying a dual shutoff valve system with a mitigation value exceeding 1.21 × 10−2 can successfully mitigate the risk of urban hydrogen refueling stations to broadly acceptable levels. [ABSTRACT FROM AUTHOR]

The average temperature of the Earth has risen due to the accumulation of greenhouse gases emitted from the usage of fossil fuels. The consequential climate changes have caused various problems, fueling the growing demand for environmentally friendly energy sources that can replace fossil fuels. Batteries and hydrogen have thus been utilized as substitute energy sources for automobiles to reduce fossil fuel consumption. Consequently, the number of hydrogen refueling stations is increasing due to an increase in the number of hydrogen-powered vehicles. However, several incidents have been reported in the United States of America and Japan where hydrogen refueling stations have been operating for a long time. A risk assessment of hydrogen refueling stations operating in urban areas was performed in this study by calculating the risk effect range using a process hazard analysis tool (PHAST) v8.7 from DNV-GL and a hydrogen risk assessment model (HyRAM) from Sandia National Laboratories (SNL). The societal risk was assessed through a probit model based on the calculation results. The assessment results showed that the risk caused by jet fire and overpressure in an incident is lower than the 'as low as reasonably practicable' (ALARP) level. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the impact of noise exposure in an intensive care unit (ICU) environment on the development of postoperative delirium in a mouse model that mimics the ICU environment. Additionally, we aimed to identify the underlying mechanisms contributing to delirium and provide evidence for reducing the risk of delirium. In this study, to mimic an ICU environment, lipopolysaccharide (LPS)-injected sepsis mouse models were exposed to a 75 dB noise condition. Furthermore, we assessed neurobehavioral function and observed the level of neuroinflammatory response and blood–brain barrier (BBB) integrity in the hippocampal region. The LPS-injected sepsis mouse model exposed to noise exhibited increased anxiety-like behavior and cognitive impairment. Moreover, severe neuroinflammation and BBB disruption were detected in the hippocampal region. This study provides insights suggesting that persistent noise exposure under systemic inflammatory conditions may cause cognitive dysfunction and anxiety- like behavior via the mediation of BBB disruption and neuroinflammation. As a result, we suggest that the detailed regulation of noise exposure may be required to prevent the development of postoperative delirium. [ABSTRACT FROM AUTHOR]

After the Paris Agreement was signed in 2015, many countries worldwide focused on the hydrogen economy, aiming for eco-friendly and renewable energy by moving away from the existing carbon economy, which has been the primary source of global warming. Hydrogen is the most common element on Earth. As a light substance, hydrogen can diffuse quickly; however, it also has a small risk of explosion. Representative explosion accidents have included the Muskingum River Power Plant Vapor Cloud Explosion accident in 2007 and the Silver Eagle Refinery Vapor Cloud Explosion accident in 2009. In addition, there was an explosion in a hydrogen tank in Gangneung, Korea, in May 2019, and a hydrogen refueling station (HRS) in Norway exploded in 2018. Despite this risk, Korea is promoting the establishment of HRSs in major urban centers, including downtown areas and public buildings, by using the Regulatory Sandbox to install HRSs. This paper employed the Hydrogen Risk Assessment Model (HyRAM) of Sandia National Laboratories (SNL), a quantitative risk assessment (QRA) program specialized in hydrogen energy for HRSs installed in major urban hubs. A feasibility evaluation of the site conditions of an HRS was conducted using the French land use planning method based on the results obtained through evaluation using the HyRAM and the overpressure results of PHAST 8.0. After a risk assessment, we confirmed that an HRS would be considered safe, even if it was installed in the city center within a radius of influence of jet fires and overpressure. [ABSTRACT FROM AUTHOR]

Semiconductor manufacturing is performed through unit processes that use various chemicals and facilities. In particular, flammable gases, such as H2, NH3, and CH4, are used, and there is a risk of explosion when such gases leak. In this study, computational fluid dynamics (CFD) simulation and a "tracer gas test" according to the SEMI (Semiconductor Equipment and Materials International) S6 Environmental, Health, and Safety Guideline for Exhaust Ventilation of Semiconductor Manufacturing Equipment specification were performed during the leakage of hydrogen, a highly flammable gas used in the etching process of a gas box in the semiconductor industry. The CFD simulation was conducted to investigate the safety of semiconductor production facilities in relation to the explosion risk. Flow analysis was performed for the interior of a gas box used in the etching process. A steady-state analysis was performed to predict the concentration range of the explosion limit in the case of continuous hydrogen gas leakage. The interior of the gas box used in the simulation was modeled, and the ventilation flow rate, which has a significant impact on the leakage gas concentration distribution, obtained from experiments was used. The lower flammability limit (LFL) value of the leaked gas was 4% based on H2, and LFL/4 (25% of the LFL) was analyzed as the explosion limit concentration according to the acceptance criteria of the SEMI S6 tracer gas test. To validate the CFD simulation, a tracer gas test was performed according to SEMI S6. A mixture of hydrogen (5%) and nitrogen (95%) was used as the tracer gas. The flow rate was controlled by a gas regulator valve and measured using an Aalborg mass flow meter. The measured concentration of the tracer gas was calculated using the equivalent release concentration, which was calculated when 100% of the hydrogen was released, and the risk was assessed by comparing it with the LFL/4 of H2. [ABSTRACT FROM AUTHOR]

In the semiconductor industry, hydrogen is used with many other hazardous and dangerous substances with flammable, toxic, and corrosive properties. In order to safely handle them, convenient-to-use gas cabinets are often required. As known well, hydrogen is highly flammable and explosive, and risk analysis needs to safely use the gas in the cabinets. In this study, overpressure and impact according to various gas cabinet conditions were measured when hydrogen leaks in the gas cabinet, and the effect of overpressure on the protective wall was simulated. For the research, a demonstration experiment was conducted by custom manufacturing a gas cylinder cabinet identical to the standard used in the field, and the protection performance analysis was performed by reverse-engineering it through 3D scanning. As a result of the demonstration experiment, the maximum pressure at the time of hydrogen gas explosion in the gas cylinder cabinet was measured at 0.3 bar. After calculating the detonation pressure propagation profile using the TNT equivalence method, the protective performance of the protective wall was confirmed using AUTODYN. The maximum stress of the concrete and the maximum stress of the reinforcing bar due to the explosion in the gas cylinder cabinet were calculated to be 30.211 MPa and 112.88 MPa, respectively, which do not exceed the tensile strength of concrete and the yield strength of the reinforcing bar. This result is expected to be of great help to the development of the semiconductor industry by suggesting the rationale for mitigating the firewall when changing the semiconductor layout. [ABSTRACT FROM AUTHOR]

The number of pressure vessel bursts (PVBs) has reduced since the 1990s due to the introduction of many rules and regulations. However, accidents frequently occur during pressure resistance tests (pneumatics) and there are scant safety guidelines for examining pressure vessels. Thus, this study proposes a safe distance to prevent accidents during a test, based on the explosion energy and vessel shape. First, the maximum explosion energy was computed using Brode's equation and the distance and overpressure were nondimensionalized via Sachs' scaling. Next, the overpressure ratio of the spherical tank (opsphere) was calculated based on the overpressure ratio of the cylindrical tank (opcylinder), considering the length to diameter ratio of the cylindrical vessel. Finally, the function of the safety distance was obtained. The result was validated by comparing it with data from the catastrophic failure that occurred at D. D. Williamson & Co. Inc. in 2003. This study could help establish safety guidelines and the prevention of PVB damage. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries (LIBs) have been used as electrochemical energy storage devices in various fields, ranging from mobile phones to electric vehicles. LIBs are composed of a positive electrode, a negative electrode, an electrolyte, and a binder. Among them, electrolytes consist of organic solvents and lithium ion conducting salts. The electrolytes used in LIBs are mostly linear and cyclic alkyl carbonates. These electrolytes are usually based on their combinations to allow the use of Li as the anodic active component, resulting in the high power and energy density of batteries. However, these organic electrolytes have high volatility and flammability that pose a serious safety issue when exposed to extreme conditions such as elevated temperatures. At that time, these electrolytes can react with active electrode materials and release a considerable amount of heat and gas. In this study, a simultaneous thermal analysis-mass spectrometry analysis was performed on six different organic solvents to examine the effect of water on hydrogen fluoride (HF) generation temperature in the electrolyte of a LIB. The electrolytes used in the experiment were anhydrous diethyl carbonate, 1,2-dimethoxyethane, ethylene carbonate, 1,3-dioxolane, tetrahydrofurfuryl alcohol, and 2-methyl-tetrahydrofuran, each containing LiPF6. The HF formation temperature was observed and compared with that when water entered the electrolyte exposed to high-temperature conditions such as fire. [ABSTRACT FROM AUTHOR]

Chemical accidents are the biggest factor that hinders the development of the chemical industry. Issuing an emergency evacuation order is one of effective ways to reduce human casualties that may occur due to chemical accidents. The present study proposes a machine learning-based decision making model for faster and more accurate decision making for the issuance of an emergency evacuation order in the event of a chemical accident. To implement the decision making model, supervised learning by the 1-Dimension Convolutional Neural Network based model was carried out using the HSEES and NTSIP data of ATSDR in the United States. An action—victim matrix was devised to determine the validity of emergency evacuation orders and the decision making model was made to learn the matrix so that the decision making model could recommend whether to execute the emergency evacuation orders or not. To make the decision making model learn the chemical accident situations, the embedding technique used in text mining was applied, and weighted learning was carried out considering the fact that learning data are asymmetric. The AUROC value for the results of the decision making by the model is 0.82, which is at a reliable level. Establishing such an emergency response decision making model using the method proposed in the present study in the mitigation stage will help the process. Among the chemical accident emergency management stages, constructing a database for the model, and using the model as a tool for quick decision making for an emergency evacuation order, is also thought to be helpful in the establishment and implementation of emergency response plans for chemical accidents. [ABSTRACT FROM AUTHOR]

A novel and effective method was devised for synthesizing a vertically aligned carbon nanotube (CNT) forest on a substrate using waste plastic obtained from commercially available water bottles. The advantages of the proposed method are the speed of processing and the use of waste as a raw material. A mechanism for the CNT growth was also proposed. The growth rate of the CNT forest was ~2.5 μm min−1. Transmission electron microscopy images indicated that the outer diameters of the CNTs were 20–30 nm on average. The intensity ratio of the G and D Raman bands was 1.27 for the vertically aligned CNT forest. The Raman spectrum showed that the wall graphitization of the CNTs, synthesized via the proposed method was slightly higher than that of commercially available multi-walled carbon nanotubes (MWCNTs). We expect that the proposed method can be easily adapted to the disposal of other refuse materials and applied to MWCNT production industries.

Polyaniline (PANI) is a promising conducting polymer for surface modification of TiO2 to achieve extended photoresponse to visible light and increased photocatalytic efficiency. In this study, we report the synthesis of a PANI/TiO2 composite with different weight ratios of PANI, which was subsequently employed for photocatalytic degradation of methylene blue (MB), bisphenol A (BPA), and bacteriophage MS2 under visible-light irradiation. The functional groups, morphology, and light response of the composite were characterized by Fourier-transform infrared spectroscopy, field-emission transmission electron microscopy, and diffuse reflectance UV–visible spectroscopy, respectively. The PANI/TiO2 composite containing 4% by weight ratio of PANI was most suitable for MB degradation, and this photocatalyst was very stable even after repeated use (four cycles). The degradation of BPA and bacteriophage MS2 by PANI/TiO2 composite reached 80% in 360 min and 96.2% in 120 min, respectively, under visible-light irradiation. Therefore, the PANI/TiO2 composite with enhanced visible-light photocatalytic efficiency and stability can be widely used for the degradation of water contaminants. [ABSTRACT FROM AUTHOR]

The facility layout problem is fundamental during the plant design. The solution of this problem has required strategies that become in numerical challenges. One of them is the exact method, which finds optimal distributions for facility layout, as demonstrated in the linear and disjunctive models. Both models are distinguished by a high quantity of nonoverlapping constraints. In contrast, a nonlinear model was formulated with low number of constraints, but it has been solved by genetic algorithms. Herein, that model is reformulated to a MINLP (mixed integer nonlinear programing) problem. The solution was possible using a visual interface linked to GAMS (General Algebraic Modeling System). Three case studies were solved to compare them. The reformulated model reached feasible solutions, and its computational time and binary variables were lower than those of the others. This suggests that the reformulated model can be extended to solve topics about process safety. [ABSTRACT FROM AUTHOR]

Liquefied natural gas (LNG) floating production storage offloading, or floating liquefied natural gas (FLNG), is an offshore unit used to produce LNG from offshore gas reservoirs. The liquefaction is critical process for liquefying natural gas (NG) into LNG. Among NG liquefaction technologies used in the industry, single mixed refrigerant, dual mixed refrigerant (DMR), and the nitrogen expansion liquefaction process have been considered for FLNG on account of its space limitations and higher safety standards. In particular, the DMR liquefaction process is preferred for a large FLNG because of its high efficiency. Many studies have been suggested about an efficiency of DMR, but a few studies have been conducted on their process safety although different configurations in process concepts can cause meaningful differences in operating conditions and safety. In this study, two DMR process configurations were optimized to maximize the efficiency and conceptual explosion risk was analyzed to compare their risk at the conceptual design stage. The results showed a difference between the explosion risks by the differences in the optimal mixed refrigerant compositions and number of devices, with similar efficiencies. These results can provide insight for a risk management strategy at the conceptual design stage, to minimize the unexpected cost generation. © 2018 American Institute of Chemical Engineers Process Process Saf Prog 38: 87–98, 2019 [ABSTRACT FROM AUTHOR]

This paper describes and reports an analysis of an explosion accident at a wastewater storage pond in South Korea, which resulted in six fatalities and one injury. This study was aimed at analyzing and determining the possibility of fracture of concrete structure by vapor cloud explosion (VCE) and ignition point of explosion, using computational fluid dynamics (CFD) for the explosion simulation. The result obtained via CFD analysis was connected with finite element analysis (FEA) to accurately review the structural damages resulting from the explosion. As a result, the mechanism of the accident was determined, and preventive solutions against such accidents are recommended. This study was aimed at analyzing and determining the possibility of fracture of concrete structure by vapor cloud explosion (VCE) and ignition point of explosion, using computational fluid dynamics (CFD) for the explosion simulation. [ABSTRACT FROM AUTHOR]

Due to numerous hazardous chemicals to handle, the process plant industry has a higher risk of fire, explosion, and toxic release than other industries. Reviewing the accidents at process plants in the past, it is clear that fire accidents occur with the highest frequency, leading this study to consider accidental fire scenarios at process plants. For the scenario of an incident, a jet fire involving a massive amount of hydrogen gas to be processed or delivered at the process plant has been selected. The analysis of incident outcome resulting from the hydrogen jet fire has been implemented through the computational fluid dynamics simulation methodology Kameleon FireEx. Based on the outcome of this simulation, the consequences of a jet fire with high temperature and heat radiation are analyzed and evaluated. In addition, the results from Phast ver. 7.11 simulation for the same scenario are presented for comparison and further validation. [ABSTRACT FROM AUTHOR]

The primary purpose of a flare model is to provide a reasonably accurate prediction of radiant heat flux at any point of interest around the flame in order to be able to define safe release locations. In order to do this, a flare model needs to provide a good prediction of the following critical flame parameters: flame length, flame tilt, and radiant heat fraction, including the impact of wind and release orientation on these parameters. In addition, the model needs to distribute the radiant heat along the flame in a reasonably realistic way and to allow for the transmissivity of the ambient air. Industry standard models for vertical flares include Chamberlain [Chamberlain, Chem Eng Res Des 65 (1987)], API 521 [API STANDARD 521, Pressure-Relieving and Depressuring Systems, 6th Edition, American Petroleum Institute, Washington DC, 2014], and Brzustowski & Sommer [API STANDARD 521, Pressure-Relieving and Depressuring Systems, 6th Edition, American Petroleum Institute, Washington DC, 2014]. These models were originally developed primarily based on hydrocarbon data. Several commercially available consequence models allow the use of these models for all flammable materials. Due to the lack of other options, these commercially available consequence software models are often applied to hydrogen, syngas (hydrogen/carbon monoxide mixtures), and other materials that are well outside the intended scope of the models. A review has been performed to evaluate applicability of the Chamberlain, API 521, and Brzustowski & Sommer models to hydrogen and syngas, including comparison with limited published data. As a result of this review, a number of significant concerns have been identified. This has led to initiation of a new test program to collect data specifically for hydrogen and syngas and the subsequent development of new models. © 2014 American Institute of Chemical Engineers Process Saf Prog 34: 141-146, 2015 [ABSTRACT FROM AUTHOR]

Hydrogen is a critical component in the production of cleaner fuels. Underground pipelines provide a safe, reliable supply of hydrogen to refineries and the petroleum industry. Proper assessment of the risks associated with underground hydrogen pipelines requires an accurate model of the jet fire consequence. This article will describe experimental and modeling work undertaken in order to define the appropriate methodology for utilizing DNV's PHAST software tool to represent the hydrogen jet fire from the rupture of underground hydrogen pipelines. Two experiments were conducted to measure the flow and radiation from an intentionally ignited rupture of a 6 in. diameter, 60 barg hydrogen pipeline buried 1 m underground. Adjustments to PHAST modeling parameters were required in order to obtain agreement between the measured and predicted radiation and flame length values. The modeling assumptions and parameter adjustments include: Velocity modification to account for interaction of the flow out of the two ends of the ruptured pipe and to model the subsequent discharge from the crater., Specification of the fraction of heat radiated., Specification of the angle of the release., © 2013 American Institute of Chemical Engineers Process Saf Prog, 2013 [ABSTRACT FROM AUTHOR]

Predicting fluid responsiveness in patients under mechanical ventilation with low tidal volume (VT) is challenging. This study evaluated the ability of carotid corrected flow time (FTc) assessed by ultrasound for predicting the fluid responsiveness during low VT ventilation. Patients under postoperative mechanical ventilation and clinically diagnosed with hypovolemia were enrolled. Carotid FTc and pulse pressure variation (PPV) were measured at VT of 6 and 10 mL/kg predicted body weight (PBW). FTc was calculated using both Bazett's (FTcB) and Wodey's (FTcW) formulas. Fluid responsiveness was defined as a ≥15% increase in the stroke volume index assessed by FloTrac/Vigileo monitor after administration of 8 mL/kg of balanced crystalloid. Among 36 patients, 16 (44.4%) were fluid responders. The areas under the receiver operating characteristic curves (AUROCs) for the FTcB at VT of 6 and 10 mL/kg PBW were 0.897 (95% confidence interval [95% CI]: 0.750–0.973) and 0.895 (95% CI: 0.748–0.972), respectively. The AUROCs for the FTcW at VT of 6 and 10 mL/kg PBW were 0.875 (95% CI: 0.722–0.961) and 0.891 (95% CI: 0.744–0.970), respectively. However, PPV at VT of 6 mL/kg PBW (AUROC: 0.714, 95% CI: 0.539–0.852) showed significantly lower accuracy than that of PPV at VT of 10 mL/kg PBW (AUROC: 0.867, 95% CI: 0.712–0.957; p = 0.034). Carotid FTc can predict fluid responsiveness better than PPV during low VT ventilation. However, further studies using automated continuous monitoring system are needed before its clinical use. [ABSTRACT FROM AUTHOR]

The use of herbal medicine has increased tremendously over the last decades, generating a considerable amount of herbal medicine waste. Pyrolysis is a promising option to dispose of biomass and organic waste such as herbal medicine waste. Herein, an activated carbon-supported Pt catalyst (Pt/AC) and carbon dioxide (CO2) were applied to the pyrolysis of real herbal medicine waste to develop a thermal disposal method to prevent the formation of benzene derivatives that are harmful to the environment and human health. When using the Pt/AC catalyst in the pyrolysis of the herbal medicine waste at 500 °C, the generation of benzyl species was suppressed. This was likely because the Pt catalytic sites accelerate a free radical mechanism that is dominant in the thermal cracking of carbonaceous substances. However, the employment of CO2 (instead of typically used N2) as a pyrolysis medium for the herbal medicine waste pyrolysis did not decrease the concentrations of benzyl compounds contained in the pyrolytic products of the herbal medicine waste. This study might help develop a method to thermally dispose of agricultural biowaste, preventing the formation of harmful chemicals to the environment and human beings. [ABSTRACT FROM AUTHOR]

Pyrolysis of polyethylene terephthalate (PET) produces polycyclic hydrocarbons and biphenyl derivatives that are harmful to human health and the environment. Therefore, a palladium metal catalyst (5 wt.% Pd loaded on activated carbon) was used to prevent the formation of harmful materials. When a Pd catalyst/PET ratio of 0.01 was applied in pyrolysis of PET, it did not show a meaningful difference in the generation of polycyclic hydrocarbons and biphenyl derivatives. However, when a Pd catalyst/PET ratio of 0.05 was used during pyrolysis, it prevented their formation and generation at experimental temperature ranges (400–700 °C). For example, the concentration of 2-naphthalenecarboxylic acid produced, which is a typical polycyclic hydrocarbon material, was reduced by 44%. In addition, the concentration of biphenyl-4-carboxylic acid, which is contained in biphenyl derivatives, was reduced by 79% compared to non-catalytic pyrolysis at 800 °C. This was because the ring-opening reaction and free radical mechanism caused by the Pd catalyst and thermal cracking were dominant during the pyrolysis of PET. Apart from these materials, amine compounds were generated as products of the pyrolysis of PET. Amine concentration showed a similar trend with polycyclic hydrocarbons and benzene derivatives. Based on these results, the total concentration of polycyclic hydrocarbons and biphenyl derivatives was compared; the results confirmed that the concentrations of all substances were reduced. This research suggests that a metal-supported catalyst will help create a more environmentally friendly and reliable method of industrial plastic waste disposal. [ABSTRACT FROM AUTHOR]

• Effectiveness of scrubbers to reduce explosion risk of ZrO 2 ALD by-product was evaluated. • Burn-wet scrubber makes the by-product more thermally stable. • Burn-wet scrubber treatment is to combust the organic residues remaining in the by-product. • Burn-wet scrubber was shown to be more effective at reducing the risk than dry scrubber. In processes of manufacturing semiconductors, reactive by-products (as a form of fine powder, i.e., dust) are deposited in pipes installed on post processing and exhaust systems, potentially involving a considerable explosion risk. In this study, the effectiveness of scrubber methods (e.g., dry scrubber and burn-wet scrubber) to mitigate the risk was evaluated. To this end, three by-products generated from a ZrO 2 atomic layer deposition (ALD) process were collected from semiconductor manufacturers, which were treated with different methods (i.e., no treatment, treatment using dry scrubber, and treatment using burn-wet scrubber), and their characteristics were analyzed and compared. Particle size measurements of the by-products proved that the burn-wet scrubber treatment less decreased their particle size than the dry scrubber treatment. The burn-wet scrubber treatment made the by-product thermally stable, confirmed by thermogravimetric analysis. Fourier-transform infrared spectroscopy of the by-products before and after the scrubber treatments showed that burn-wet scrubbing of the by-product decreases surface functionalities that play a role in explosion. Dust explosion testing proved that robustness of explosion of the untreated by-product is about 7 times higher than the by-product treated with the burn-wet scrubber. Based on the results of this study, it would be suggested that burn-wet scrubber is a useful treatment method to decrease the explosion risks caused by dust by-products generated from ALD in semiconductor manufacturing processes. [ABSTRACT FROM AUTHOR]

Purpose: Perioperative fluid management in kidney transplant recipients is crucial to supporting the fluid, acid-base, and electrolyte balance required for graft perfusion. However, the choice of intraoperative crystalloids in kidney transplantation remains controversial. We conducted a single-center retrospective cohort study to evaluate the impact of intraoperative fluids on acid-base and electrolyte balance and graft outcomes., Materials and Methods: We included 282 living donor kidney transplant recipients from January 2010 to December 2017. Patients were classified into two groups based on the type of intraoperative crystalloids used (157 patients in the half saline group and 125 patients in the balanced crystalloid solutions group, Plasma-lyte)., Results: Compared with the half saline group, the Plasma-lyte group showed less metabolic acidosis and hyponatremia during surgery. Hyperkalemia incidence was not significantly different between the two groups. Changes in postoperative graft function assessed by blood urea nitrogen and creatinine were significantly different between the two groups. Patients in the Plasma-lyte group exhibited consistently higher glomerular filtration rates than those in the half saline group at 1 month and 1 year after transplantation after adjusting for demographic differences., Conclusion: Intraoperative Plasma-lyte can lead to more favorable results in terms of acid-base balance during kidney transplantation. Patients who received Plasma-lyte showed superior postoperative graft function at 1 month and 1 year after transplantation. Further studies are needed to evaluate the superiority of intraoperative Plasma-lyte over other types of crystalloids in relation to graft outcomes., Competing Interests: The authors have no potential conflicts of interest to disclose., (© Copyright: Yonsei University College of Medicine 2022.)

Background: Although the use of volatile sedatives in the intensive care unit (ICU) is increasing in Europe, it remains infrequent in Asia. Therefore, there are no clinical guidelines available. This study investigates the proper initial concentration of sevoflurane, a volatile sedative that induces a Richmond agitation-sedation scale (RASS) score of -2 to -3, in patients who underwent head and neck surgery with tracheostomy. We also compared the amount of postoperative opioid consumption between volatile and intravenous (IV) sedation., Methods: We planned a prospective study to determine the proper initial sevoflurane concentration and a retrospective analysis to compare postoperative opioid consumption between volatile sedation and propofol sedation. Patients scheduled for head and neck surgery with tracheostomy and subsequent postoperative sedation in the ICU were enrolled., Results: In this prospective study, the effective dose 50 (ED50) of initial end-tidal sevoflurane concentration was 0.36% (95% confidence interval [CI], 0.20 to 0.60%), while the ED 95 was 0.69% (95% CI, 0.60 to 0.75%) based on isotonic regression methods. In this retrospective study, remifentanil consumption during postoperative sedation was significantly lower in the sevoflurane group (2.52±1.00 µg/kg/hr, P=0.001) than it was in the IV propofol group (3.66±1.30 µg/kg/hr)., Conclusions: We determined the proper initial end-tidal concentration setting of sevoflurane for patients with tracheostomy who underwent head and neck surgery. Postoperative sedation with sevoflurane appears to be a valid and safe alternative to IV sedation with propofol.