High-Performance Indoor Perovskite Solar Cells by Self-Suppression of Intrinsic Defects via a Facile Solvent-Engineering Strategy.

Lead halide perovskite solar cells have been emerging as very promising candidates for applications in indoor photovoltaics. To maximize their indoor performance, it is of critical importance to suppress intrinsic defects of the perovskite active layer. Herein, a facile solvent-engineering strategy is developed for effective suppression of both surface and bulk defects in lead halide perovskite indoor solar cells, leading to a high efficiency of 35.99% under the indoor illumination of 1000 lux Cool-white light-emitting diodes. Replacing dimethylformamide (DMF) with N-methyl-2-pyrrolidone (NMP) in the perovskite precursor solvent significantly passivates the intrinsic defects within the thus-prepared perovskite films, prolongs the charge carrier lifetimes and reduces non-radiative charge recombination of the devices. Compared to the DMF, the much higher interaction energy between NMP and formamidinium iodide/lead halide contributes to the markedly improved quality of the perovskite thin films with reduced interfacial halide deficiency and non-radiative charge recombination, which in turn enhances the device performance. This work paves the way for developing efficient indoor perovskite solar cells for the increasing demand for power supplies of Internet-of-Things devices.

Controllable Acceleration and Deceleration of Charge Carrier Transport in Metal-Halide Perovskite Single-Crystal by Cs-Cation Induced Bandgap Engineering.

Charge carrier transport in materials is of essential importance for photovoltaic and photonic applications. Here, the authors demonstrate a controllable acceleration or deceleration of charge carrier transport in specially structured metal-alloy perovskite (MACs)PbI3 (MA= CH3 NH3 ) single-crystals with a gradient composition of CsPbI3 /(MA1- x Csx )PbI3 /MAPbI3 . Depending on the Cs-cation distribution in the structure and therefore the energy band alignment, two different effects are demonstrated: i) significant acceleration of electron transport across the depth driven by the gradient band alignment and suppression of electron-hole recombination, benefiting for photovoltaic and detector applications; and ii) decelerated electron transport and thus improved radiative carrier recombination and emission efficiency, highly beneficial for light and display applications. At the same time, the top Cs-layer results in hole localization in the top layer and surface passivation. This controllable acceleration and deceleration of electron transport is critical for various applications in which efficient electron-hole separation and suppressed nonradiative electron-hole recombination is demanded.

Inner Ear Symptoms Are Prevalent in Patients with High Head Abbreviated Injury Scale Scores after Blunt Head Trauma.

INTRODUCTION: The purpose of this article was to determine the prevalence of inner ear symptoms in patients with blunt head trauma and to explore whether the severity of head trauma was associated with the incidence of such symptoms. METHODS: We performed a retrospective review of 56 patients admitted with blunt head trauma who underwent audiovestibular evaluation within 1 month after injury. Two scales were used to measure the severity of trauma; these were the Glasgow Coma Scale (GCS) and the Head Abbreviated Injury Scale (H-AIS). Patients with sensorineural-type hearing loss, or dizziness with nystagmus, were considered to have inner ear symptoms. RESULTS: About half of all patients (45%) with blunt head trauma showed trauma-related inner ear symptoms. Patients with inner ear symptoms were significantly more likely to have H-AIS scores ≥4 than those without inner ear symptoms (p = 0.004), even without concomitant temporal bone fracture (p > 0.05). Also, patients with inner ear symptoms required a statistically significantly longer time (measured from admission) before undergoing their ontological evaluations than did those without such symptoms (p = 0.002), possibly due to prolonged bed rest and use of sedatives. CONCLUSION: Thus, detailed history-taking and early evaluation using trauma scales are essential for all patients suffering from severe head trauma. It may be necessary to initiate early treatment of traumatic inner ear diseases.

National Follow-up Survey of Preventable Trauma Death Rate in Korea.

BACKGROUND: The preventable trauma death rate survey is a basic tool for the quality management of trauma treatment because it is a method that can intuitively evaluate the level of national trauma treatment. We conducted this study as a national biennial follow-up survey project and report the results of the review of the 2019 trauma death data in Korea. METHODS: From January 1, 2019 to December 31, 2019, of a total of 8,482 trauma deaths throughout the country, 1,692 were sampled from 279 emergency medical institutions in Korea. All cases were evaluated for preventability of death and opportunities for improvement using a multidisciplinary panel review approach. RESULTS: The preventable trauma death rate was estimated to be 15.7%. Of these, 3.1% were judged definitive preventable deaths, and 12.7% were potentially preventable deaths. The odds ratio for preventable traumatic death was 2.56 times higher in transferred patients compared to that of patients who visited the final hospital directly. The group that died 1 hour after the accident had a statistically significantly higher probability of preventable death than that of the group that died within 1 hour after the accident. CONCLUSION: The preventable trauma death rate for trauma deaths in 2019 was 15.7%, which was 4.2%p lower than that in 2017. To improve the quality of trauma treatment, the transfer of severe trauma patients to trauma centers should be more focused.

Periodic nanostructures: preparation, properties and applications.

Periodic nanostructures, a group of nanomaterials consisting of single or multiple nano units/components periodically arranged into ordered patterns (e.g., vertical and lateral superlattices), have attracted tremendous attention in recent years due to their extraordinary physical and chemical properties that offer a huge potential for a multitude of applications in energy conversion, electronic and optoelectronic applications. Recent advances in the preparation strategies of periodic nanostructures, including self-assembly, epitaxy, and exfoliation, have paved the way to rationally modulate their ferroelectricity, superconductivity, band gap and many other physical and chemical properties. For example, the recent discovery of superconductivity observed in "magic-angle" graphene superlattices has sparked intensive studies in new ways, creating superlattices in twisted 2D materials. Recent development in the various state-of-the-art preparations of periodic nanostructures has created many new ideas and findings, warranting a timely review. In this review, we discuss the current advances of periodic nanostructures, including their preparation strategies, property modulations and various applications.

Effect of early enteral nutrition on the incidence of acute acalculous cholecystitis among trauma patients.

BACKGROUND AND OBJECTIVES: Acute acalculous cholecystitis (AAC) often occurs in critically ill patients, especially in those that have experienced trauma, surgery, shock, and prolonged fasting. Early enteral nutrition has been shown to significantly reduce morbidity and mortality compared to other nutritional support strategies. The purpose of this study was to evaluate the effect of early enteral nutrition on the incidence of AAC among trauma patients. METHODS AND STUDY DESIGN: Multi-strategy nutritional protocol was implemented in the intensive care unit (ICU) in 2016 for early enteral nutrition and proper nutritional support. The traumatized critically-ill patients without volitional intake who were admitted to ICU between 2015 and 2017 were included. Basic characteristics, duration of fasting, and the incidence of percutaneous cholecystostomy (PC) due to AAC were analyzed according to the year. RESULTS: Enteral nutrition was indicated in 552 trauma patients (28.2%). The mean duration of fasting was shortened from 6.5 days in 2015 to 5.4 days in 2017 (p=0.202). The incidence of PC was significantly decreased from 2015 to 2017 [6/171 (3.5%) vs. 6/204 (2.9%) vs. 0/177 (0%), p=0.023]. The provision of central parenteral nutrition (p=0.001) and fasting over 7 days (p=0.014) proved to be a risk factor of AAC. CONCLUSIONS: This study showed that the incidence of PC due to AAC was decreased significantly after the implementation of a nutritional protocol among traumatized critically ill patients. Early enteral nutrition may be effective in reducing the AAC among trauma patients who are at high risk of AAC.

Preventable Trauma Death Rate after Establishing a National Trauma System in Korea.

BACKGROUND: This study aimed to evaluate the current overall preventable trauma death rate (PTDR) in Korea and identify factors associated with preventable trauma death (PTD). METHODS: The target sample size for review was designed to be 1,131 deaths in 60 emergency medical institutions nationwide. The panels for the review comprised trauma specialists working at the regional trauma centers (RTCs); a total of 10 teams were formed. The PTDR and factors associated with PTD were analyzed statistically. RESULTS: Of the target cases, 943 were able to undergo panel review and be analyzed statistically. The PTDR was 30.5% (6.1% preventable and 24.4% possibly preventable). Those treated at a RTC showed a significantly lower PTDR than did those who were not (21.9% vs. 33.9%; P = 0.002). The PTDR was higher when patients were transferred from other hospitals than when they directly visited the last hospital (58.9% vs. 28.4%; P = 0.058; borderline significant). The PTDR increased gradually as the time from accident to death increased; a time of more than one day had a PTDR 14.99 times higher than when transferred within one hour (95% confidence interval, 4.68 to 47.98). CONCLUSION: Although the PTDR in Korea is still high compared to that in developed countries, it was lower when the time spent from the accident to the death was shorter and the final destined institution was the RTC. To reduce PTDR, it is necessary to make an effort to transfer trauma patients to RTCs directly within an appropriate time.

Biomimetic Silica Nanocapsules for Tunable Sustained Release and Cargo Protection.

Silica nanocapsules have attracted tremendous interest for encapsulation, protection, and controlled release of various cargoes due to their unique hierarchical core-shell structure. However, it remains challenging to synthesize silica nanocapsules having high cargo-loading capacity and cargo-protection capability without compromising process simplicity and biocompatibility properties. Here, we synthesized oil-core silica-shell nanocapsules under environmentally friendly conditions by a novel emulsion and biomimetic dual-templating approach using a dual-functional protein, in lieu of petrochemical surfactants, thus avoiding the necessities for the removal of toxic components. A light- and pH-sensitive compound can be facilely encapsulated in the silica nanocapsules with the encapsulation efficiency of nearly 100%. Release of the encapsulated active from the nanocapsules was not shown an indication of undesired burst release. Instead, the release can be tuned by controlling the silica-shell thicknesses (i.e., 40 and 77 nm from which the cargo released at 42.0 and 31.3% of the initial amount after 32 days, respectively). The release kinetics were fitted well to the Higuchi model, enabling the possibility of the prediction of release kinetics as a function of shell thickness, thus achieving design-for-purpose silica nanocapsules. Furthermore, the nanocapsules showed excellent alkaline- and sunlight-shielding protective efficacies, which resulted in significantly prolonged half-life of the sensitive cargo. Our biomimetic silica nanocapsules provide a nanocarrier platform for applications that demand process scalability, sustainability, and biocompatibility coupled with unique cargo-protection and controlled-release properties.

An Electrochemically Treated BiVO4 Photoanode for Efficient Photoelectrochemical Water Splitting.

BiVO4 films with (040) facet grown vertically on fluorine doped SnO2 (FTO) glass substrates are prepared by a seed-assisted hydrothermal method. A simple electrochemical treatment process drastically enhances the photocatalytic activity of BiVO4 , exhibiting a remarkable photocurrent density of 2.5 mA cm-2 at 1.23 V vs. reversible hydrogen electrode (RHE) under AM 1.5 G illumination, which is approximately 10-fold higher than that of the pristine photoanode. Loading cobalt borate (CoBi) as cocatalyst, the photocurrent density of the BiVO4 photoanode can be further improved to 3.2 mA cm-2 , delivering an applied bias photon-to-current efficiency (ABPE) of 1.1 %. Systematic studies reveal that crystal facet orientation also synergistically boosts both charge separation and transfer efficiencies, resulting in remarkably enhanced photocurrent densities. These findings provide a facile and effective approach for the development of efficient photoelectrodes for photoelectrochemical water splitting.

Stable and low-cost mesoscopic CH3NH3PbI2 Br perovskite solar cells by using a thin poly(3-hexylthiophene) layer as a hole transporter.

Mesoscopic perovskite solar cells using stable CH3 NH3 PbI2 Br as a light absorber and low-cost poly(3-hexylthiophene) (P3HT) as hole-transporting layer were fabricated, and a power conversion efficiency of 6.64 % was achieved. The partial substitution of iodine with bromine in the perovskite led to remarkably prolonged charge carrier lifetime. Meanwhile, the replacement of conventional thick spiro-MeOTAD layer with a thin P3HT layer has significantly reduced the fabrication cost. The solar cells retained their photovoltaic performance well when they were exposed to air without any encapsulation, presenting a favorable stability. The combination of CH3 NH3 PbI2 Br and P3HT may render a practical and cost-effective solid-state photovoltaic system. The superior stability of CH3 NH3 PbI2 Br is also promising for other photoconversion applications.

Adenosine-induced transient asystole during intracranial aneurysm surgery: indications, dosing, efficacy, and risks.

BACKGROUND: Several flow-arrest techniques have been introduced for the treatment of complex aneurysms that cannot be treated with conventional clipping or endovascular coil embolization. Adenosine-induced transient asystole is an alternative method of flow arrest. However, given the limited number of studies that have reported on this topic, there is no consensus regarding the dose, regimen, efficacy, and potential risks of adenosine. METHOD: A total of 22 aneurysms in 22 different patients that underwent adenosine-induced transient asystole during aneurismal neck clipping within the past 4 years were retrospectively reviewed. Adenosine was administrated intravenously in a test-incremental manner (starting with 6-12 mg and then giving additional doses as needed) in 11 patients and in an estimated manner (pre-calculated as 0.3-0.4 mg/kg) in 11 patients. RESULTS: Overall, the study consisted of 18 unruptured saccular aneurysms, three ruptured saccular aneurysms, and a ruptured pseudoaneurysm. Adenosine-induced transient asystole was used in cases of temporary clipping inability, wide necked aneurysm, deep-seated aneurysm, or a thin aneurysm wall. The number of administrations, dose (mg/kg in ideal body weight) and duration of asystole were 1-4 (mean, 2.3) times, 0.08-1.27 (mean, 0.36) mg/kg and 0-30 (mean 13) seconds in the test-incremental manner and 1-2 (mean, 1.09) times, 0.24-0.42 (mean, 0.34) mg/kg and 13-41 (mean, 24) seconds in the estimated manner, respectively. There was a linear relationship between the dose and the duration of asystole. Twenty out of 22 aneurysms were clipped successfully with adenosine-induced transient asystole. However, in the other two cases, additional suction decompression was required for the final clipping. Adenosine-related cardiologic complications occurred in two cases of self-limited atrial fibrillation during restoration of the cardiac rhythm. CONCLUSIONS: In our experience, adenosine-induced transient asystole was safe and helpful for satisfactory clipping of a complicated aneurysm. An estimated dose injection of adenosine was more convenient than the test-incremental method and did not result in serious cardiologic problems.

The Efficacy of Traumatic Brain Injury Treatment by Neurotrauma Specialists.

Objective: Since the establishment of Regional Trauma Centers (RTCs) in Korea, significant efforts have been made to improve the quality of care for patients with trauma. Simultaneously, the Department of Neurosurgery assigned neurotrauma specialists to RTCs to provide specialized care to patients with traumatic brain injury (TBI). In this study, we sought to determine whether neurotrauma specialists, compared to general neurosurgeons, could make a significant difference in treatment outcomes of patients with TBI. Methods: In total, 156 patients with acute TBI who required decompression were included. We reviewed their records and compared the characteristics, outcomes, and prognosis of those who received surgical treatment from either neurotrauma specialists or general neurosurgeons at our institution. Results: A significant difference was observed between treatment by trauma neurosurgery specialists and general neurosurgeons in time to surgery, with trauma specialists experiencing shorter surgical delays. However, no significant differences existed in mortality rates or Extended Glasgow Outcome Scale scores. Univariate and multivariable regression analyses revealed that lower Glasgow Coma Scale scores, an abnormal pupil reflex, larger transfusion volume, and prolonged time from emergency room admission to surgery were associated with high mortality rates. Conclusion: Neurotrauma specialists can provide prompt surgical treatment to patients with TBI compared to general neurosurgeons. Our study did not reveal a significant difference in outcomes between the two groups. However, it is clear that rapid decompression is effective in patients with impending brain herniation. Therefore, the effectiveness of neurotrauma specialists needs to be confirmed through further systematic studies.

Hypertrophic olivary degeneration following surgical resection or gamma knife radiosurgery of brainstem cavernous malformations: an 11-case series and a review of literature.

BACKGROUND: We describe 11 patients with hypertrophic olivary degeneration (HOD) after surgical resection or gamma knife radiosurgery for brainstem cavernous malformations. In addition, we statistically analyzed the predicting factors associated with the development of HOD. METHODS: From January 2001 to May 2011, a total of 73 patients (30 in the surgical group and 43 in the radiosurgery group) with brainstem cavernous malformations were treated in our institute. Of them, 11 patients (incidence: 15 %) developed HOD with high signal intensity on T2-weighted MRI during follow-up. The predicting factors (location, size, age, and treatment method) associated with the development of HOD were statistically analyzed. RESULTS: Among the 11 HOD patients, seven patients received surgical resection and four patients received gamma knife radiosurgery. Six patients had bilateral HOD and the remaining five patients had unilateral HOD. Overall HOD-associated symptoms presented in four patients, including three palatal tremors and one ataxia. In all four patients with symptoms, these symptoms disappeared incompletely within the clinical follow-up period. The size of the cavernous malformation, age of patient, and treatment methods were not significantly correlated with the development of HOD. A significantly higher incidence of HOD was associated with midbrain cavernous malformations than with pontine or medulla cavernous malformations. CONCLUSIONS: HOD should be recognized as a non-infrequent complication of surgical resection or gamma knife radiosurgery within the brainstem, especially for midbrain cavernous malformations. In addition, to the best of our knowledge, this is the first report on HOD development after radiosurgery.

Risk Factors for Postoperative Contralateral Hemorrhage in Patients With Traumatic Brain Injury who Underwent Surgical Treatment: A Multicenter Study.

Objective: Patients with a contralateral intracranial hemorrhage after decompressive craniectomy have a worse prognosis than those whose recovery is uneventful. Therefore, the objective of this study was to identify risk factors for postoperative contralateral hemorrhage (PCH) in patients who underwent unilateral craniectomy or craniotomy due to a traumatic brain injury (TBI). Methods: Data were obtained from the Korean Neuro-Trauma Data Bank System and retrospectively reviewed. Patients who had a unilateral craniectomy or craniotomy for acute TBI were included in this study. Clinical outcomes of a PCH group and an uneventful group were compared and the risk factors for PCH were identified using regression analysis. Results: A total of 326 patients were included in this study. PCH was observed in 25 (7.7%) patients. The Glasgow coma scale (GCS) and Glasgow outcome scale extended (GOSE) scores at discharge were significantly lower in the PCH group than those in the uneventful group (GCS: 3.6 vs. 6.2, p=0.043; GOSE: 2.1 vs. 3.2, p=0.032). In the multivariable regression analysis, when the time from injury to surgery was shorter than 150 minutes, the risk of PCH was increased by 4.481 times (p=0.005). When the intraoperative transfusion volume was more than 1.5 L, the risk of PCH was increased by 4.843 times (p=0.003). Conclusion: The risk of PCH is increased when the time from injury to surgery is shorter than 150 minutes and when the intraoperative transfusion volume is greater than 1.5 L. Neurosurgeons must predict and be prepared for the development of PCH in high-risk patients.

Anticoagulation and Antiplatelet Agent Resumption Timing following Traumatic Brain Injury.

Traumatic brain injury (TBI) is a major global health concern. Due to the increase in TBI incidence and the aging population, an increasing number of patients with TBI are taking antithrombotic agents for their underlying disease. When TBI occurs in patients with these diseases, there is a conflict between the disease, which requires an antithrombotic effect, and the neurosurgeon, who must minimize intracranial hemorrhage. Nevertheless, there are no clear guidelines for the reversal or resumption of antithrombotic agents when TBI occurs in patients taking antithrombotic agents. In this review article, we intend to classify antithrombotic agents and provide information on them. We also share previous studies on the reversal and resumption of antithrombotic agents in patients with TBI to help neurosurgeons in this dilemma.

Dual functional WO3/BiVO4 heterostructures for efficient photoelectrochemical water splitting and glycerol degradation.

Dual functional heterojunctions of tungsten oxide and bismuth vanadate (WO3/BiVO4) photoanodes are developed and their applications in photoelectrochemical (PEC) water splitting and mineralization of glycerol are demonstrated. The thin-film WO3/BiVO4 photoelectrode was fabricated by a facile hydrothermal method. The morphology, chemical composition, crystalline structure, chemical state, and optical absorption properties of the WO3/BiVO4 photoelectrodes were characterized systematically. The WO3/BiVO4 photoelectrode exhibits a good distribution of elements and a well-crystalline monoclinic WO3 and monoclinic scheelite BiVO4. The light-absorption spectrum of the WO3/BiVO4 photoelectrodes reveals a broad absorption band in the visible light region with a maximum absorption of around 520 nm. The dual functional WO3/BiVO4 photoelectrodes achieved a high photocurrent density of 6.85 mA cm-2, which is 2.8 times higher than that of the pristine WO3 photoelectrode in the presence of a mixture of 0.5 M Na2SO4 and 0.5 M glycerol electrolyte under AM 1.5 G (100 mW cm-2) illumination. The superior PEC performance of the WO3/BiVO4 photoelectrode was attributed to the synergistic effects of the superior crystal structure, light absorption, and efficient charge separation. Simultaneously, glycerol plays an essential role in increasing the efficiency of hydrogen production by suppressing charge recombination in the water redox reaction. Moreover, the WO3/BiVO4 photoelectrode shows the total organic carbon (TOC) removal efficiency of glycerol at about 82% at 120 min. Notably, the WO3/BiVO4 photoelectrode can be a promising photoelectrode for simultaneous hydrogen production and mineralization of glycerol with a simple, economical, and environmentally friendly approach.

Pharmacological Management of Germinal Matrix-Intraventricular Hemorrhage.

Germinal matrix-intraventricular hemorrhage (GM-IVH) is among the devastating neurological complications with mortality and neurodevelopmental disability rates ranging from 14.7% to 44.7% in preterm infants. The medical techniques have improved throughout the years, as the morbidity-free survival rate of very-low-birth-weight infants has increased; however, the neonatal and long-term morbidity rates have not significantly improved. To this date, there is no strong evidence on pharmacological management on GM-IVH, due to the limitation of well-designed randomized controlled studies. However, recombinant human erythropoietin administration in preterm infants seems to be the only effective pharmacological management in limited situations. Hence, further high-quality collaborative research studies are warranted in the future to ensure better outcomes among preterm infants with GM-IVH.

Surface plasmon-driven photoelectrochemical water splitting of a Ag/TiO2 nanoplate photoanode.

A silver/titanium dioxide nanoplate (Ag/TiO2 NP) photoelectrode was designed and fabricated from vertically aligned TiO2 nanoplates (NP) decorated with silver nanoparticles (NPs) through a simple hydrothermal synthesis and electrodeposition route. The electrodeposition times of Ag NPs on the TiO2 NP were crucial for surface plasmon-driven photoelectrochemical (PEC) water splitting performance. The Ag/TiO2 NP at the optimal deposition time of 5 min with a Ag element content of 0.53 wt% demonstrated a remarkably high photocurrent density of 0.35 mA cm-2 at 1.23 V vs. RHE under AM 1.5G illumination, which was 5 fold higher than that of the pristine TiO2 NP. It was clear that the enhanced light absorption properties and PEC performance for Ag/TiO2 NP could be effectively adjusted by simply controlling the loading amounts of metallic Ag NPs (average size of 10-30 nm) at different electrodeposition times. The superior PEC performance of the Ag/TiO2 NP photoanode was attributed to the synergistic effects of the plasmonic Ag NPs and the TiO2 nanoplate. Interestingly, the plasmonic effect of Ag NPs not only increased the visible-light response (λ max = 570 nm) of TiO2 but also provided hot electrons to promote photocurrent generation and suppress charge recombination. Importantly, this study offers a potentially efficient strategy for the design and fabrication of a new type of TiO2 hybrid nanostructure with a plasmonic enhancement for PEC water splitting.

Nanosphere Lithography: A Versatile Approach to Develop Transparent Conductive Films for Optoelectronic Applications.

Transparent conductive films (TCFs) are irreplaceable components in most optoelectronic applications such as solar cells, organic light-emitting diodes, sensors, smart windows, and bioelectronics. The shortcomings of existing traditional transparent conductors demand the development of new material systems that are both transparent and electrically conductive, with variable functionality to meet the requirements of new generation optoelectronic devices. In this respect, TCFs with periodic or irregular nanomesh structures have recently emerged as promising candidates, which possess superior mechanical properties in comparison with conventional metal oxide TCFs. Among the methods for nanomesh TCFs fabrication, nanosphere lithography (NSL) has proven to be a versatile platform, with which a wide range of morphologically distinct nanomesh TCFs have been demonstrated. These materials are not only functionally diverse, but also have advantages in terms of device compatibility. This review provides a comprehensive description of the NSL process and its most relevant derivatives to fabricate nanomesh TCFs. The structure-property relationships of these materials are elaborated and an overview of their application in different technologies across disciplines related to optoelectronics is given. It is concluded with a perspective on current shortcomings and future directions to further advance the field.

National trauma system establishment based on implementation of regional trauma centers improves outcomes of trauma care: A follow-up observational study in South Korea.

Although South Korea is a high-income country, its trauma system is comparable to low- and middle-income countries with high preventable trauma death rates of more than 30%. Since 2012, South Korea has established a national trauma system based on the implementation of regional trauma centers and improvement of the transfer system; this study aimed to evaluate its effectiveness. We compared the national preventable trauma death rates, transfer patterns, and outcomes between 2015 and 2017. The review of preventable trauma deaths was conducted by multiple panels, and a severity-adjusted logistic regression model was created to identify factors influencing the preventable trauma death rate. We also compared the number of trauma patients transferred to emergency medical institutions and mortality in models adjusted with injury severity scores. The preventable trauma death rate decreased from 2015 to 2017 (30.5% vs. 19.9%, p < 0.001). In the severity-adjusted model, the preventable trauma death risk had a lower odds ratio (0.68, 95% confidence interval: 0.53-0.87, p = 0.002) in 2017 than in 2015. Regional trauma centers received 1.6 times more severe cases in 2017 (according to the International Classification of Diseases Injury Severity Score [ICISS]; 23.1% vs. 36.5%). In the extended ICISS model, the overall trauma mortality decreased significantly from 2.1% (1008/47 806) to 1.9% (1062/55 057) (p = 0.041). The establishment of the national trauma system was associated with significant improvements in the performance and outcomes of trauma care. This was mainly because of the implementation of regional trauma centers and because more severe patients were transferred to regional trauma centers. This study might be a good model for low- and middle-income countries, which lack a trauma system.