Objectives Physician-staffed ambulances enable physicians to deliver advanced interventions at the scene of emergencies. In Japan, these systems have expanded nationwide since their first deployment in 1979, yet it remains unclear whether research attention has been well-balanced across clinical conditions. We conducted a scoping review of physician-staffed ambulance research in Japan to identify well-studied areas and knowledge gaps. Methods A scoping review was conducted using MEDLINE, Web of Science, CINAHL, and CENTRAL (searched May 28, 2024) without date or language restrictions. Eligible studies were original, peer-reviewed English-language articles evaluating physician-staffed ambulances in Japan. Two reviewers independently screened records and extracted data, including study characteristics, target populations, disease categories, outcomes, and author affiliations. Results Of 795 records identified, 29 studies met inclusion criteria. Publications increased notably after 2011. Nearly half (48.3%) targeted adult patients and 6.9% focused on pediatric patients. The most common conditions studied were cardiopulmonary arrest (51.7%), followed by trauma (17.2%) and acute coronary syndrome (6.9%). Most studies (86.2%) were retrospective observational studies. Common primary endpoints were neurological outcomes (34.5%), particularly one-month favorable outcomes, and mortality (31.0%). Data sources frequently included ambulance transport records (51.7%), out-of-hospital cardiac arrest registries, and the Japan Trauma Data Bank. University hospitals accounted for 72.4% of first and corresponding author affiliations. Conclusions This scoping review found that research on physician-staffed ambulances in Japan is concentrated on cardiac arrest and trauma, with little evaluation of non-traumatic medical emergencies or long-term outcomes. Future studies should expand disease coverage, include varied outcomes, and tailor strategies to regional needs.

Objectives Japan’s physician-staffed helicopter emergency medical services (HEMS) are widely deployed but published evidence is heterogeneous across indications, outcomes and study designs. We aimed to map the internationally reported, English-language literature evaluating physician-staffed HEMS in Japan and to identify evidence gaps requiring further research.Design Scoping review was conducted using established methodological frameworks and reported in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR).Data sources MEDLINE, Web of Science, CINAHL and the Cochrane Library, supplemented by backward and forward citation tracking.Eligibility criteria Original studies evaluating physician-staffed HEMS in Japan and reporting patient outcomes for any emergency condition published in English-language journals.Methods We conducted a systematic database search using terms related to physician-staffed HEMS in Japan. The original search (28 May 2024) was updated on 25 February 2026 using the same eligibility criteria. Two reviewers independently performed title/abstract screening followed by full-text screening to determine eligibility. We additionally performed backward and forward citation tracking of the included studies. We summarised characteristics of eligible studies descriptively using counts and proportions.Results The updated search identified 341 records, and citation tracking identified 16 further studies, yielding 76 included studies. Publications increased over time (2016–2020: 32.9%; 2021–2026: 52.6%). Most studies were single-centre observational (55.3%) or registry-based (39.5%), with few multi-centre studies (5.3%). Trauma was the most frequent study population (25.0%), and mortality the most common primary outcome (35.5%). First authors were university-affiliated in 88.2% of studies, 39.5% appeared in a single aeromedical journal, and no study compared physician-staffed with non-physician HEMS.Conclusion The internationally reported, English-language literature on physician-staffed HEMS in Japan has expanded over time, but remains dominated by retrospective observational designs, is produced largely by university-affiliated authors, and is concentrated in a small number of journals. Prospective multi-centre evaluation, comparison with non-physician HEMS, functional and longer-term outcomes, and economic evaluation were absent from the identified literature.

Extracorporeal cardiopulmonary resuscitation (ECPR) requires advanced skills for induction and management. This study evaluated whether the outcomes of ECPR differ by institutional volume. Using the Japanese Association for Acute Medicine–Out-of-Hospital Cardiac Arrest (JAAM-OHCA) registry, we analyzed adult patients (aged ≥18 years) who received ECPR between 2014 and 2020, focusing on 30 day in-hospital survival and favorable neurologic prognosis at 30 days defined as Cerebral Performance Category (CPC) 1–2. Facilities were categorized into tertiles by annual ECPR volume. Multivariable logistic regression examined outcomes across low (≤4.7 cases/year), medium (4.8–7.8 cases/year), and high (≥7.9 cases/year) volume groups. A total of 1,759 patients from 83 centers were included, with an overall 30 day survival of 21.1% and CPC 1–2 rate of 10.1%. We observed no statistically significant differences in the respective rates of 30 day survival and neurologic outcomes in the medium ECPR volume group (adjusted odds ratios 1.09 [95% confidence interval {CI}, 0.82–1.47] and 0.85 [0.56–1.26]) and higher ECPR volume group (adjusted odds ratios 1.27 [95% CI, 0.95–1.70] and 1.11 [0.75–1.63]) compared with the lower ECPR volume group. These findings suggest that ECPR outcomes for out-of-hospital cardiac arrest are not significantly affected by institutional ECPR volume.

BackgroundResearch has described differences in the provision of prehospital treatment for women who experience out-of-hospital cardiac arrest. However, studies have reported conflicting results regarding survival outcomes or in-hospital interventions between sexes. Thus, this study aimed to investigate the association of sex with survival outcomes and in-hospital treatments in Japan.MethodsWe retrospectively analyzed data from the Japanese Association for Acute Medicine–Out-of-Hospital Cardiac Arrest Registry. Patients aged ≥18 years who presented with a shockable rhythm at the scene between June 2014 and December 2020 were included in our analysis. Outcome measures were 30-day survival and in-hospital interventions. We compared the outcomes between the sexes using multivariable logistic regression.ResultsIn total, 5,926 patients (4,270 men; 1,026 women) with out-of-hospital cardiac arrest were eligible for our analysis. The proportions of patients with 30-day survival outcomes were 39.5% (1685/4,270) and 37.4% (384/1,026) in the male and female groups, respectively (crude odds ratio, 0.92; 95% confidence interval, 0.80–1.06). Although there were no significant differences, survival outcomes tended to be better in women than in men in the multiple regression analysis (adjusted odds ratio: 1.38; 95% confidence interval: 0.82–2.33). Furthermore, there was no significant difference between the sexes in terms of patients who received extracorporeal cardiopulmonary resuscitation (adjusted odds ratio: 0.81; 95% confidence interval: 0.49–1.33) or targeted temperature management (adjusted odds ratio: 0.99; 95% confidence interval: 0.68–1.46).ConclusionsAfter adjusting for prognostic factors, there were no differences in survival rates and in-hospital interventions between men and women.

Aim: Life-threatening electrocardiographic (ECG) findings aid in the diagnosis of acute coronary syndrome (ACS), which has not been well -evaluated in patients with out-of-hospital cardiac arrest (OHCA). This study aimed to evaluate the diagnostic test accuracy (DTA) of ST-elevation myocardial infarction (STEMI) equivalents following the return of spontaneous circulation (ROSC) in patients with OHCA to identify patients with ACS.Methods: Using the database of the Comprehensive Registry of In-Hospital Intensive Care for OHCA Survival study from 2012 to 2017, patients aged >= 18 years with non-traumatic OHCA and ventricular fibrillation or pulseless ventricular tachycardia on the arrival of emergency medical service personnel or arrival at the emergency department, who achieved ROSC, were included. Patients without ST-segment elevation or complete left bun-dle branch block on ECG and those who did not undergo ECG or coronary angiography, were excluded from the study. We evaluated the DTA of STEMI equivalents for the diagnosis of ACS: isolated T-wave inversion, ST-segment depression, Wellens' signs, and ST-segment elevation in lead aVR.Results: Isolated T-wave inversion and Wellens' signs had high specificity for ACS with 0.95 (95% confidence interval [CI], 0.87-0.99) and 0.92 (95% CI, 0.82-0.97), respectively, but their positive likelihood ratios were low, with a wide range of 95% CI: 1.89 (95% CI, 0.51-7.02) and 0.81 (95% CI, 0.25-2.68), respectively.Conclusion: The DTA of STEMI equivalents for the diagnosis of ACS was low among patients with OHCA. Further investigation considering the measurement timing of the ECG after ROSC is required.

Background: We aimed to investigate the association between blood urea nitrogen to creatinine ratio (BCR) and survival with favourable neurological outcomes in patients with out-of-hospital cardiac arrest (OHCA). Methods: This prospective, multicentre, observational study conducted in Osaka, Japan enrolled consecutive OHCA patients transported to 16 participating institutions from 2012 through 2019. We included adult patients with non-traumatic OHCA who achieved a return of spontaneous circulation and whose blood urea nitrogen and creatinine levels on hospital arrival were available. Based on BCR values, they were divided into: 'low BCR' (BCR <10), 'normal BCR' (10 <= BCR < 20), 'high BCR' (20 <= BCR < 30), and 'very high BCR' (BCR >= 30). We evaluated the association between BCR values and neurologically favourable outcomes, defined as cerebral performance cate-gory score of 1 or 2 at one month after OHCA. Results: Among 4415 eligible patients, the 'normal BCR' group had the highest favourable neurological outcome [19.4 % (461/2372)], followed by 'high BCR' [12.5 % (141/1127)], 'low BCR' [11.2 % (50/445)], and 'very high BCR' groups [6.6% (31/471)]. In the multivariable analysis, adjusted odds ratios for 'low BCR', 'high BCR', and 'very high BCR' compared with 'normal BCR' for favourable neurological outcomes were 0.58 [95 % confidence interval (CI 0.37-0.91)], 0.70 (95 % CI 0.49-0.99), and 0.40 (95 % CI 0.21-0.76), respectively. Cubic spline analysis indicated that the association between BCR and favourable neurological outcomes was non-linear (p for non-linearity = 0.003). In subgroup analysis, there was an interaction between the aetiology of arrest and BCR in neurological outcome (p for interaction <0.001); favourable neurological outcome of cardiogenic OHCA patients was lower when the BCR was higher or lower, but not in non-cardiogenic OHCA patients. Conclusions: Both higher and lower BCR were associated with poor neurological outcomes compared to normal BCR, especially in cardiogenic OHCA patients. (c) 2023 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.

Background: The effectiveness of IABP for shockable out-of-hospital cardiac arrest (OHCA) has not been extensively investigated. This study aimed to investigate whether the use of an intra-aortic balloon pump (IABP) for non-traumatic shockable OHCA patients was associated with favorable neurological outcomes. Methods: From the Japanese Association for Acute Medicine Out-of-Hospital Cardiac Arrest registry, a nationwide multicenter prospective registry, we enrolled adult patients with non-traumatic and shockable OHCA for whom resuscitation was attempted, and who were transported to participating hospitals between 2014 and 2019. The primary outcome was 1-month survival with favorable neurological outcomes after OHCA. After adopting the propensity score (PS) inverse probability of weighting (IPW), we evaluated the association between IABP and favorable neurological outcomes. Results: Of 57,754 patients in the database, we included a total of 2738 adult non-traumatic shockable patients. In the original cohort, the primary outcome was lower in the IABP group (OR with 95% confidence intervals (CIs)), 0.57 (0.48–0.68), whereas, in the IPW cohort, it was not different between patients with and without IABP (OR, 1.18; 95% CI, 0.91–1.53). Conclusion: In adult patients with non-traumatic shockable OHCA, IABP use was not associated with 1-month survival with favorable neurological outcomes.

Background: Extracorporeal cardiopulmonary resuscitation (ECPR) has been focused as a rescue therapy for the refractory cardiac arrest patients; however, little is known about the effect of ECPR on survival. The aim of this study is to evaluate the association between ECPR and the survival among the out-of-hospital cardiac arrest patients. Method: This was the secondary analysis of JAAM-OHCA registry which is a nationwide multicenter prospective study collecting the data of out-of-hospital cardiac arrest patients from July 2012 to December 2019. The study participant were adult (≥18 years) cardiac arrest patients due to internal medical cause. Initial cardiac rhythm was stratified as initial shockable and non-shockable rhythm. Patients received ECPR were sequentially matched with the patients who had not yet received within the same minutes (control) based on the time-dependent propensity scores calculated from the patient characteristics to eliminate the resuscitation time bias. Odds ratio with 95% confidence interval (CI) of ECPR for the 30-day survival were calculated by conditional logistic model. Results: Of 57,754 patients in the JAAM-OHCA registry, 1,826 matched cohort with initial shockable rhythm (913 treated with ECPR and 913 control) and 740 matched cohort with initial non-shockable rhythm (370 treated with ECPR and 370 control) were eligible for analysis. Their characteristics between with ECPR and control were well balanced. In the matched cohort with initial shockable rhythm, 30-day survival was 24.6% (225/913) in the patients with ECPR and 16.3% (149/913) in the control. In the matched cohort with initial non-shockable rhythm, 30-day survival was 11.9% (44/370) in the patients with ECPR and 2.4% (9/370) in the control. Odds ratio of with ECPR for 30-day survival was 1.76 [95%CI: 1.38-2.25] in shockable rhythm and 5.37 [95%CI: 2.53- 11.43] in non-shockable rhythm, referred to the control. Conclusion: This time-dependent propensity score sequential matching analysis suggested that ECPR was associated with the 30-day survival outcomes among the out-of-hospital cardiac arrest patients with both initial shockable and non-shockable rhythms.

Objective: Sex disparities in out-of-hospital cardiac arrest (OHCA) care processes have been reported. This study aimed to investigate the association between sex and prehospital advanced cardiac life support (ACLS) interven-tions provided by emergency medical services in Japan. Methods: We analyzed data from January 1, 2013, to December 31, 2020, from the All-Japan Utstein Registry of patients with OHCA aged >= 18 years who were resuscitated by bystanders. The primary outcomes were prehos-pital ACLS interventions, including advanced airway management (AAM) and epinephrine administration. Sex-based disparities in receiving prehospital ACLS interventions were assessed via multivariable logistic regres-sion analyses. Results: Among 314,460 eligible patients, females with OHCA received fewer prehospital ACLS interventions than males: 83,571/187,834 (44.5%) males vs. 55,086/126,626 (43.5%) females (adjusted odds ratio [AOR] = 0.94, 95% confidence interval [CI] = 0.93-0.96) for AAM and 60,097/187,834 (32.0%) males vs. 35,501/126,626 (28.0%) fe-males (AOR = 0.84, 95% CI = 0.83-0.85) for epinephrine administration. Similar results were also obtained in the subgroup analysis (groups included patients aged 18-74 years and >= 75 years and those with cardiac origin, ven-tricular fibrillation (VF), non-VF, non-family member witnessed, and family member witnessed). Conclusion: Compared with males, females were less likely to receive prehospital ACLS. Emergency medical ser-vice staff must be made aware of this disparity, and off-the-job training on intravenous cannulation or AAM re-placement must be conducted. Investigation of the impact of sex disparity on OHCA care processes can facilitate planning of future public health policies to improve survival outcomes. (c) 2022 Elsevier Inc. All rights reserved.

Abstract Background Singapore and Osaka in Japan have comparable population sizes and prehospital management; however, the frequency of ECPR differs greatly for out-of-hospital cardiac arrest (OHCA) patients with initial shockable rhythm. Given this disparity, we hypothesized that the outcomes among the OHCA patients with initial shockable rhythm in Singapore were different from those in Osaka. The aim of this study was to evaluate the outcomes of OHCA patients with initial shockable rhythm in Singapore compared to the expected outcomes derived from Osaka data using machine learning-based prediction models. Methods This was a secondary analysis of two OHCA databases: the Singapore PAROS database (SG-PAROS) and the Osaka-CRITICAL database from Osaka, Japan. This study included adult (18–74 years) OHCA patients with initial shockable rhythm. A machine learning-based prediction model was derived and validated using data from the Osaka-CRITICAL database (derivation data 2012–2017, validation data 2018–2019), and applied to the SG-PAROS database (2010–2016 data), to predict the risk-adjusted probability of favorable neurological outcomes. The observed and expected outcomes were compared using the observed–expected ratio (OE ratio) with 95% confidence intervals (CI). Results From the SG-PAROS database, 1,789 patients were included in the analysis. For OHCA patients who achieved return of spontaneous circulation (ROSC) on hospital arrival, the observed favorable neurological outcome was at the same level as expected (OE ratio: 0.905 [95%CI: 0.784–1.036]). On the other hand, for those who had continued cardiac arrest on hospital arrival, the outcomes were lower than expected (shockable rhythm on hospital arrival, OE ratio: 0.369 [95%CI: 0.258–0.499], and nonshockable rhythm, OE ratio: 0.137 [95%CI: 0.065–0.235]). Conclusion This observational study found that the outcomes for patients with initial shockable rhythm but who did not obtain ROSC on hospital arrival in Singapore were lower than expected from Osaka. We hypothesize this is mainly due to differences in the use of ECPR.

PURPOSE: Previous research has described differences in the provision of prehospital treatment for women who experience outof-hospital cardiac arrest (OHCA).However, some studies have reported conflicting results regarding survival outcomes or inhospital interventions between the sexes.The aim of this study was to investigate the association of gender with survival outcomes and in-hospital treatments, such as post-resuscitation care, in Japan. METHODS:This was a retrospective analysis of data from the Japanese Association for Acute Medicine (JAAM)-OHCA Registry, a multicenter nationwide prospective database in Japan in which 137 institutions providing emergency care participated.We included OHCA patients aged $ 18 years who presented with a shockable rhythm at the scene between June 2014 and December 2020.The outcome measure was 30-day survival and in-hospital interventions.We compared the outcomes between gender groups using multivariable logistic regression.RESULTS: A total of 5926 adult OHCA patients were eligible for our analysis.Of these patients, 4270 were men and 1026 were women.The proportions of patients with 30-day survival outcomes were 39.5% (1685/4270) and 37.4% (384/1026) in the men and women groups, respectively [crude odds ratio 0.92, 95% confidence interval (CI) 0.80-1.06].Although there was no significant difference, survival outcomes tended to be better in women than men in the multiple regression analysis [adjusted odds ratio (AOR) 1.38, 95% CI 0.82-2.33].Furthermore, there was no significant difference between the sexes in terms of patients who received ECPR (AOR, 0.81; 95% CI, 0.49-1.33)or TTM (AOR, 0.99; 95% CI, 0.68-1.46). CONCLUSIONS:After adjusting for prognostic factors, there was no difference in survival rates and in-hospital interventions between men and women. CLINICAL IMPLICATIONS:The treatment of OHCA in hospitals has seen a surge in specialized interventions such as extracorporeal cardio-pulmonary resuscitation (ECPR) or targeted temperature management (TTM) or percutaneous coronary intervention (PCI), making them standard protocol globally.However, despite these advances, there is a lack of research on sexrelated differences in receiving in-hospital treatments and post-resuscitation care.In this study, we evaluated the association of gender with the survival outcomes of OHCA with shockable rhythm at the scene or in-hospital interventions using JAAM-OHCA nationwide registry.There was no difference between women and men in terms of in survival outcome and hospital interventions, and this result was constant in the subgroup analysis.

BACKGROUND:The hypothesis of this study is that latent class analysis could identify the subphenotypes of out-of-hospital cardiac arrest (OHCA) patients associated with the outcomes and allow us to explore heterogeneity in the effects of extracorporeal cardiopulmonary resuscitation (ECPR). METHODS AND RESULTS:This study was a retrospective analysis of a multicenter prospective observational study (CRITICAL study) of OHCA patients. It included adult OHCA patients with initial shockable rhythm. Patients from 2012 to 2016 (development dataset) were included in the latent class analysis, and those from 2017 (validation dataset) were included for evaluation. The association between subphenotypes and outcomes was investigated. Further, the heterogeneity of the association between ECPR implementation and outcomes was explored. In the study results, a total of 920 patients were included for latent class analysis. Three subphenotypes (Groups 1, 2, and 3) were identified, mainly characterized by the distribution of partial pressure of O2(PO2), partial pressure of CO2(PCO2) value of blood gas assessment, cardiac rhythm on hospital arrival, and estimated glomerular filtration rate. The 30-day survival outcomes were varied across the groups: 15.7% in Group 1; 30.7% in Group 2; and 85.9% in Group 3. Further, the association between ECPR and 30-day survival outcomes by subphenotype groups in the development dataset was as varied. These results were validated using the validation dataset. CONCLUSIONS:The latent class analysis identified 3 subphenotypes with different survival outcomes and potential heterogeneity in the effects of ECPR.

Background The association between spontaneous initial body temperature on hospital arrival and neurological outcomes has not been sufficiently studied in patients after out-of-hospital cardiac arrest (OHCA). Methods From the prospective database of the Comprehensive Registry of Intensive Care for OHCA Survival (CRITICAL) study in Osaka, Japan, we enrolled all patients with OHCA of medical origin aged > 18 years for whom resuscitation was attempted and who were transported to participating hospitals between 2012 and 2019. We excluded patients who were not witnessed by bystanders and treated by a doctor car or helicopter, which is a car/helicopter with a physician. The patients were categorized into three groups according to their temperature on hospital arrival: ≤35.9 °C, 36.0–36.9 °C (normothermia), and ≥ 37.0 °C. The primary outcome was 1-month survival, with a cerebral performance category of 1 or 2. Multivariable logistic regression analyses were performed to evaluate the association between temperature and outcomes (normothermia was used as the reference). We also assessed this association using cubic spline regression analysis. Results Of the 18,379 patients in our database, 5014 witnessed adult OHCA patients of medical origin from 16 hospitals were included. When analyzing 3318 patients, OHCA patients with an initial body temperature of ≥37.0 °C upon hospital arrival were associated with decreased favorable neurological outcomes (6.6% [19/286] odds ratio, 0.51; 95% confidence interval, 0.27–0.95) compared to patients with normothermia (16.4% [180/1100]), whereas those with an initial body temperature of ≤35.9 °C were not associated with decreased favorable neurological outcomes (11.1% [214/1932]; odds ratio, 0.78; 95% confidence interval, 0.56–1.07). The cubic regression splines demonstrated that a higher body temperature on arrival was associated with decreased favorable neurological outcomes, and a lower body temperature was not associated with decreased favorable neurological outcomes. Conclusions In adult patients with OHCA of medical origin, a higher body temperature on arrival was associated with decreased favorable neurologic outcomes.

Background: Out-of-hospital cardiac arrest (OHCA) patients with acute coronary syndrome (ACS) needs emergent coronary angiography and subsequent percutaneous coronary intervention to improve their outcomes. ‘STEMI equivalents’ in electrocardiogram (ECG) are known to help the diagnosis of ACS. However, these findings have not been sufficiently evaluated among OHCA patients. This study aimed to evaluate the diagnostic test accuracy (DTA) of ‘STEMI equivalents’ to identify ACS among OHCA patients without ST-segment elevation. Methods/Results: Nine emergency medical departments among the Comprehensive Registry of In-Hospital Intensive Care for OHCA Survival (CRITICAL) study in Osaka, Japan collected the patients' first 12 leads ECGs after return of spontaneous circulation (ROSC) from 2012 to 2017. Patients with non-traumatic OHCA aged >=18 years old with ventricular fibrillation / pulseless ventricular tachycardia as first documented rhythm or rhythm at hospital arrival were included. Of them, patients without ST-segment elevation nor complete left bundle branch block were extracted. The DTAs; sensitivity, specificity, positive likelihood ratio (LR+), and negative and likelihood ratio (LR-) of STEMI equivalents (i.e., Isolated T-wave inversion, Wellens signs) for the diagnosis of the ACS were evaluated. ACS was diagnosed by the physicians in each hospital based on the coronary angiography. Results: A total of 143 cases were included in the analysis and 79 patients were diagnosed as ACS. Isolated T-wave inversion was found in 7 (3.2%) patients in the ACS group and 3 (8.8%) in the non-ACS group. The Wellens signs was present in 5 (6.3%) and 5 (7.8%) patients, respectively. The isolated T-wave inversion and the Wellens signs had high specificity with 0.95 (95% CI: 0.87-0.99) and 0.92 (95% CI: 0.82-0.97), whereas these findings had low LR+ with wide range of 95% CI with 1.89 (95% CI: 0.51-7.02), and 0.81 (95% CI: 0.25-2.68), respectively. Conclusion: In this study, the DTA of STEMI equivalents of single 12 leads ECG alone were not sufficient for the diagnosis of ACS after ROSC among OHCA patients without ST-segment elevation. Further investigation of the DTA evaluation considering the measurement timing and the change of the ECG is needed.

Aim: Extracorporeal cardiopulmonary resuscitation (ECPR) is performed in refractory out-of-hospital cardiac arrest (OHCA) patients, and the eligibility has been conventionally determined based on three criteria (initial cardiac rhythm, time to hospital arrival within 45 minutes, and age <75 years) in Japan. Owing to limited information, this study descriptively determined neurological outcomes after applying the three criteria among OHCA patients who underwent ECPR. Methods: This study conducted a post-hoc analysis of data from the Comprehensive Registry of Intensive Care for OHCA Survival (CRITICAL) study. This was a multi-institutional prospective observational study of OHCA patients in Osaka Prefecture, Japan. All adult (aged >= 18 years) OHCA patients with internal medical causes treated with ECPR between 1 July 2012 and 31 December 2019 were evaluated. We described one-month neurological favourable outcomes based on the three criteria (initial shockable, time to hospital arrival within 45 minutes, and age <75 years), and we compared them using the chi-square test. Results: Among 18,379 patients screened from the CRITICAL study database, we included 517 OHCA patients treated by ECPR; 311 (60.2%) patients met all three criteria. Favourable neurological outcomes were as follows: patients meeting no or one criterion: 2.3% (1/43), those meeting two criteria: 8% (13/163), and those meeting all criteria: 16.1% (50/311) (P-value = 0.004). Conclusions: In this study, approximately 60% of patients treated by ECPR met the three criteria (initial shockable, time to hospital arrival within 45 minutes, and age <75 years), and the greater the number of criteria met, the better were the neurological outcomes achieved.

AimThe coronavirus disease (COVID‐19) pandemic has led to an increase in out‐of‐hospital cardiac arrests (OHCAs) and mortality. However, there has been no reports in Japan using nationwide registry data. We compared survival among patients with OHCAs and detailed information on the cause during the COVID‐19 pandemic (2020), and during the pre‐pandemic period (2019).MethodsUsing a Japanese population‐based retrospective cohort study design, we analyzed registry data on 39,324 and 39,170 patients with OHCAs in 2019 and 2020, respectively. We compared patient outcomes in 2019 and 2020 using univariable and multivariable logistic regression analyses.ResultsThe proportion of OHCAs of cardiac origin increased significantly from 61.6% in 2019 to 62.7% in 2020 (P = 0.001). The use of bystander CPR (6.9% versus 5.7%, P < 0.001) and publicaccess automated external defibrillator pads (3.7% versus 3.0%, P < 0.001) decreased significantly from 2019 to 2020. The 1‐month survival for OHCA of cardiac origin (12.1% versus 10.7%; adjusted odds ratio [OR] 0.93, 95% confidence interval [CI] 0.87–1.00), asphyxia (10.9% versus 8.8%; adjusted OR 0.80, 95% CI 0.70–0.92), and external causes (adjusted OR 0.66; 95% CI 0.46–0.96), also decreased significantly from 2019 to 2020.ConclusionsIn Japan, the 1‐month survival after OHCA of cardiac origin, or due to asphyxia or external causes, decreased significantly during the COVID‐19 pandemic period.

Introduction: Estimating prognosis after out-of-hospital cardiac arrest (OHCA) at early timing during resuscitation efforts is important to select appropriate candidates for extracorporeal cardiopulmonary resuscitation (ECPR). The TiPS65 scoring system is a prediction model that can be used for predicting favorable neurological outcome of adult OHCA patients treated with ECPR using the following four variables: time from call to hospital arrival, initial cardiac rhythm on hospital arrival, initial pH value, and age. However, it is not yet externally validated. We aimed to perform the external validation of the TiPS65 score. Methods: This prognostic study used data from the Japanese Association for Acute Medicine Out-of-Hospital Cardiac Arrest registry, a nationwide, multicenter, prospectively registered database including 83 emergency departments in Japan from January 2018 to December 2019. All adult OHCA patients with shockable rhythm who were treated with ECPR were included. The primary outcome was 30-day survival with favorable neurological outcome defined as Cerebral Performance Category 1 or 2. The predicted probability of outcomes in this cohort was calculated according to the formula developed in the original study. The discrimination and calibration performances were investigated with c-statistic and calibration plots, respectively. Results: A total of 590 patients (men: 517 [81.6%], median age [interquartile range]: 60 [50-69] years) were included, and favorable neurological outcome were reported in 64 (10.8%). The c-statistic of the prediction model was 0.752 (95% CI: 0.694-0.81). The mean predicted probabilities were 1.6% (range: 1.6%-1.6%), 4.5% (3.1%-5.9%), 12% (10.1%-13.9%), 26.2% (22.7%-29.7%), and 48.8% (48.8%-48.8%) for a TiPS65 score of 0, 1, 2, 3, and 4, respectively. These scores were generally well-calibrated to the observed outcomes. Conclusions: In our external validation study of the TiPS65 score for OHCA patients treated with ECPR, the score showed good discrimination and calibration performances. This score would be helpful in the decision-making process for patient selection for ECPR after OHCA.

Dysnatremia is an electrolytic disorder commonly associated with mortality in various diseases. However, little is known about dysnatremia in out-of-hospital cardiac arrest (OHCA) cases. Here, we investigated the association between serum sodium level on hospital arrival and neurological outcomes after OHCA. This nationwide hospital-based observational study (The Japanese Association for Acute Medicine Out-of-Hospital Cardiac Arrest registry) enrolled patients with OHCA between 2014 and 2017. We included adult patients aged ≥ 18 years with non-traumatic OHCA who achieved return of spontaneous circulation (ROSC) and whose serum sodium level on hospital arrival was available. Based on the serum sodium level, patients were divided into three levels: hyponatremia (Na < 135 mEq/L), normal sodium level (Na ≥ 135 or ≤ 145 mEq/L), and hypernatremia (Na > 145 mEq/L). The primary outcome was 1-month survival with favourable neurological outcomes. Altogether, 34 754 patients with OHCA were documented, and 5160 patients with non-traumatic OHCA and who achieved ROSC were eligible for our analyses. The proportion of favourable neurological outcomes was highest in patients with normal sodium levels at 17.6% (677/3854), followed by patients with hyponatremia at 8.2% (57/696) and patients with hypernatremia at 5.7% (35/610). Moreover, hyponatremia and hypernatremia were associated with a decreased probability of favourable neurological outcomes compared with normal sodium level (vs. hyponatremia, adjusted odds ratio [AOR] 0.97, 95% confidence interval [CI] 0.95–0.99; vs. hypernatremia, AOR 0.96, 95% CI 0.94–0.98). Hypo- and hypernatremia on hospital arrival were associated with a decreased probability of favourable neurological outcomes in patients with non-traumatic OHCA who achieved ROSC.

Aim We aimed to identify subphenotypes among patients with out‐of‐hospital cardiac arrest (OHCA) with initial non‐shockable rhythm by applying machine learning latent class analysis and examining the associations between subphenotypes and neurological outcomes. Methods This study was a retrospective analysis within a multi‐institutional prospective observational cohort study of OHCA patients in Osaka, Japan (the CRITICAL study). The data of adult OHCA patients with medical causes and initial non‐shockable rhythm presenting with OHCA between 2012 and 2016 were included in machine learning latent class analysis models, which identified subphenotypes, and patients who presented in 2017 were included in a dataset validating the subphenotypes. We investigated associations between subphenotypes and 30‐day neurological outcomes. Results Among the 12,594 patients in the CRITICAL study database, 4,849 were included in the dataset used to classify subphenotypes (median age: 75 years, 60.2% male), and 1,465 were included in the validation dataset (median age: 76 years, 59.0% male). Latent class analysis identified four subphenotypes. Odds ratios and 95% confidence intervals for a favorable 30‐day neurological outcome among patients with these subphenotypes, using group 4 for comparison, were as follows; group 1, 0.01 (0.001–0.046); group 2, 0.097 (0.051–0.171); and group 3, 0.175 (0.073–0.358). Associations between subphenotypes and 30‐day neurological outcomes were validated using the validation dataset. Conclusion We identified four subphenotypes of OHCA patients with initial non‐shockable rhythm. These patient subgroups presented with different characteristics associated with 30‐day survival and neurological outcomes.