ImportanceThe effect of large-scale disasters on bystander cardiopulmonary resuscitation (BCPR) performance is unknown.ObjectiveTo investigate whether and how large-scale earthquake and tsunami as well as subsequent nuclear pollution influenced BCPR performance for out-of-hospital cardiac arrest (OHCA) witnessed by family and friends/colleagues.Design and settingRetrospective analysis of prospectively collected, nationwide, population-based data for OHCA cases.ParticipantsFrom the nationwide OHCA registry recorded between 11 March 2010 and 1 March 2013, we extracted 74 684 family-witnessed and friend/colleague-witnessed OHCA cases without prehospital physician involvement.ExposureEarthquake and tsunamis that were followed by nuclear pollution and largely affected the social life of citizens for at least 24 weeks.Main outcome and measureNeurologically favourable outcome after 1 month, 1-month survival and BCPR.MethodsWe analysed the 4-week average trend of BCPR rates in the years affected and before and after the disaster. We used univariate and multivariate logistic regression analyses to investigate whether these disasters affected BCPR and OHCA results.ResultsMultivariable logistic regression for tsunami-affected prefectures revealed that the BCPR rate during the impact phase in 2011 was significantly lower than that in 2010/2012 (42.5% vs 48.2%; adjusted OR; 95% CI 0.82; 0.68 to 0.99). A lower level of bystander compliance with dispatcher-assisted CPR instructions (62.1% vs 69.5%, 0.72; 95% CI 0.57 to 0.92) in the presence of a preserved level of voluntary BCPR performance (23.6% vs 23.8%) was also observed. Both 1-month survival and neurologically favourable outcome rates during the impact phase in 2011 were significantly poorer than those in 2010/2012 (8.5% vs 10.7%, 0.72; 95% CI 0.52 to 0.99, 4.0% vs 5.2%, 0.62; 95% CI 0.38 to 0.98, respectively).Conclusion and relevanceA large-scale disaster with nuclear pollution influences BCPR performance and clinical outcomes of OHCA witnessed by family and friends/colleagues. Basic life-support training leading to voluntary-initiated BCPR might serve as preparedness for disaster and major accidents.

Background: Many out-of-hospital cardiac arrest cases are unwitnessed. For both unwitnessed and witnessed cases, recent guidelines endorse the dispatcher’s instruction of compression-only cardiopulmonary resuscitation to lay rescuers without previous resuscitation training. This study aimed to investigate the changes in the composition of bystander resuscitation based on the combination of rescue breathing and dispatcher-assisted resuscitation, and the association of the changes in bystander resuscitation content with annual outcome improvement in unwitnessed out-of-hospital cardiac arrest cases.Method: Retrospective analysis of prospective national cohort study in a population-based setting. Out-of-hospital cardiac arrest cases in 2009–2016 (986,760 cases) were reviewed to provide a complete dataset for analyses (941,858 cases). Main outcome was neurologically favorable survival at 1 month.Results: Of the 941,858 cases, the rates of neurologically favorable survival adjusted for prehospital confounders continuously increased annually. When classified into 5 groups according to the contents of resuscitation, the proportions of the dispatcher-assisted compression-only resuscitation group increased annually, whereas the proportions of the other groups decreased. That is, the shift from standard (defined as the combination of chest compressions and rescue breathings) to compression-only bystander resuscitation were observed for both unwitnessed and bystander-witnessed cases. In unwitnessed cases, the survival rate of the dispatcher-assisted compression-only resuscitation group was always lower than that of the no-resuscitation group during the study period. On the other hand, the survival rate of dispatcher-assisted standard resuscitation group exceeded that of the no-resuscitation group at the end of the study period (adjusted odds ratio; 95% confidence intervals (CI), 1.41; 1.02–1.93), and the increase in survival rate was prominent compared to that of the dispatcher-assisted compression-only resuscitation group (adjusted unit odds ratio/year; 95% CI, 1.15; 1.08–1.24 vs. 1.04; 1.00–1.07).Conclusions: The proportions of dispatcher-assisted compression-only resuscitation group increased annually, but its survival rate of the neurologically favorable 1-month did not exceed compared to that of the no-resuscitation group in unwitnessed cases. The dispatcher-assisted compression-only resuscitation did not appear to be an ideal management for unwitnessed out-of-hospital cardiac arrest cases.

This study aimed to clarify the epidemiology of out of-hospital cardiac arrest (OHCA) cases caused by hypothermia. The associations between the presence/absence of shockable initial electrocardiography rhythm, prehospital defibrillation and the outcomes of OHCA were also investigated. This study involved the retrospective analysis of prospectively collected, nationwide, population-based data for OHCA cases caused by hypothermia. One thousand five hundred seventy-five emergency medical service (EMS)-confirmed OHCA cases with hypothermia, recorded between 2013 and 2019, were extracted from the Japanese nationwide database. The primary outcome was neurologically favorable 1-month survival, defined as cerebral performance category 1 or 2. The secondary outcome was 1-month survival. OHCA cases with hypothermia occurred more frequently in the winter. In approximately half (837) of the hypothermic OHCA cases, EMS was activated in the morning (6:00 am to 11:59 am). Shockable initial electrocardiogram rhythms were recorded in 30.8% (483/1570) of cases. prehospital defibrillation was attempted in 96.1% (464/483) of cases with shockable rhythms and 25.8% (280/1087) of cases with non-shockable initial rhythms. EMS-witnessed cases, prolonged transportation time intervals and prehospital epinephrine administration were associated with rhythm conversion in cases with non-shockable initial rhythms. Binominal logit test followed by multivariable logistic regression revealed that shockable initial rhythms were associated with better outcomes. prehospital defibrillation was not significantly associated with better outcomes, regardless of the type of initial rhythm (shockable or non-shockable). Transportation to high-level emergency hospitals was associated with better outcomes (adjusted odds ratio: 2.94, 95% confidence interval: 1.66–5.21). In hypothermic OHCA, shockable initial rhythm but not prehospital defibrillation is likely to be associated with better neurologically favorable outcomes. In addition, transport to a high-level acute care hospital may be appropriately considered despite prolonged transport. Further investigation, including core temperature data in analyses, is necessary to determine the benefit of prehospital defibrillation in hypothermic OHCA.

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Objectives: This study aimed to analyse the effects of rescue breath and chest compression combinations in bystander cardiopulmonary resuscitation (BCPR) with and without dispatch-assisted CPR (DA) on the outcomes between unwitnessed and bystander-witnessed out-of-hospital cardiac arrest (OHCA).Design and Settings: This retrospective study analysed the prospectively collected data of 212,003 unwitnessed and 117,920 bystander-witnessed OHCA cases between 2014 and 2016 in Japan, with BCPR classification based on two clinical components (DA provision [with or without DA] and combination of breaths and compressions [standard or compression-only]).Main outcome measures: Neurologically favourable outcome at 1 monthResults: In univariate analysis, unwitnessed cases had no significant association of BCPR with the overall neurologically favourable outcome (provided vs not provided, 0.65% [686/106,152] vs 0.66% [694/105,851]) compared with bystander-witnessed cases (5.6% [3,538/62,814] vs 3.5% [1,911/55,106]). After BCPR classification by two clinical components, the outcome of unwitnessed cases was improved by standard BCPR with DA (0.88% [69/7,807], adjusted OR; 95% CI, 1.38; 1.05–1.81) and compression-only (1.04% [161/15,497], 1.49;1.23–1.80) and standard (1.18% [41/3,463], 1.71; 1.21–2.43) BCPR without DA, but not by compression-only BCPR with DA (0.52% [415/79,385], 0.88; 0.76–1.01). According to multivariable logistic regression analysis focusing on the two clinical components only in cases with BCPR, neurologically favourable outcomes were worse in DA provision (0.76; 0.60–0.97) but better in standard BCPR, (1.27; 1.01–1.60) without significant interaction (P = 0.16), in unwitnessed cases. In bystander-witnessed cases, DA provision was associated with better outcomes (1.27; 1.01–1.60), with significant interaction (P = 0.03).Conclusions: Compared with no BCPR, compression-only BCPR with DA does not improve the neurologically favourable outcomes, and standard BCPR without DA is ideal in unwitnessed OHCA cases. Education on standard CPR and chest compression-only CPR as an option should be maintained because numerous OHCA cases are not witnessed by bystanders.