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Background: This study aimed to investigate the association between the temporal transitions in heart rhythms during cardiopulmonary resuscitation (CPR) and outcomes after out-of-hospital cardiac arrest., Methods: This was an analysis of the prospectively collected databases in 3 academic hospitals in northern and central Taiwan. Adult patients with out-of-hospital cardiac arrest transported by emergency medical service between 2015 and 2022 were included. Favorable neurological recovery and survival to hospital discharge were the primary and secondary outcomes, respectively. Time-specific heart rhythm shockability was defined as the probability of shockable rhythms at a particular time point during CPR. The temporal changes in the time-specific heart rhythm shockability were calculated by group-based trajectory modeling. Multivariable logistic regression analyses were performed to examine the association between the trajectory group and outcomes. Subgroup analyses examined the effects of extracorporeal CPR in different trajectories., Results: The study comprised 2118 patients. The median patient age was 69.1 years, and 1376 (65.0%) patients were male. Three distinct trajectories were identified: high-shockability (52 patients; 2.5%), intermediate-shockability (262 patients; 12.4%), and low-shockability (1804 patients; 85.2%) trajectories. The median proportion of shockable rhythms over the course of CPR for the 3 trajectories was 81.7% (interquartile range, 73.2%-100.0%), 26.7% (interquartile range, 16.7%-37.5%), and 0% (interquartile range, 0%-0%), respectively. The multivariable analysis indicated both intermediate- and high-shockability trajectories were associated with favorable neurological recovery (intermediate-shockability: adjusted odds ratio [aOR], 4.98 [95% CI, 2.34-10.59]; high-shockability: aOR, 5.40 [95% CI, 2.03-14.32]) and survival (intermediate-shockability: aOR, 2.46 [95% CI, 1.44-4.18]; high-shockability: aOR, 2.76 [95% CI, 1.20-6.38]). The subgroup analysis further indicated extracorporeal CPR was significantly associated with favorable neurological outcomes (aOR, 4.06 [95% CI, 1.11-14.81]) only in the intermediate-shockability trajectory., Conclusions: Heart rhythm shockability trajectories were associated with out-of-hospital cardiac arrest outcomes, which may be a supplementary factor in guiding the allocation of medical resources, such as extracorporeal CPR., Competing Interests: None.

Background Public health emergencies may significantly impact emergency medical services responses to cardiovascular emergencies. We compared emergency medical services responses to out-of-hospital cardiac arrest (OHCA) and ST-segment‒elevation myocardial infarction (STEMI) during the 2020 COVID-19 pandemic to 2018 to 2019 and evaluated the impact of California's March 19, 2020 stay-at-home order. Methods and Results We conducted a population-based cross-sectional study using Los Angeles County emergency medical services registry data for adult patients with paramedic provider impression (PI) of OHCA or STEMI from February through May in 2018 to 2020. After March 19, 2020, weekly counts for PI-OHCA were higher (173 versus 135; incidence rate ratios, 1.28; 95% CI, 1.19‒1.37; P <0.001) while PI-STEMI were lower (57 versus 65; incidence rate ratios, 0.87; 95% CI, 0.78‒0.97; P =0.02) compared with 2018 and 2019. After adjusting for seasonal variation in PI-OHCA and decreased PI-STEMI, the increase in PI-OHCA observed after March 19, 2020 remained significant ( P =0.02). The proportion of PI-OHCA who received defibrillation (16% versus 23%; risk difference [RD], -6.91%; 95% CI, -9.55% to -4.26%; P <0.001) and had return of spontaneous circulation (17% versus 29%; RD, -11.98%; 95% CI, -14.76% to -9.18%; P <0.001) were lower after March 19 in 2020 compared with 2018 and 2019. There was also a significant increase in dead on arrival emergency medical services responses in 2020 compared with 2018 and 2019, starting around the time of the stay-at-home order ( P <0.001). Conclusions Paramedics in Los Angeles County, CA responded to increased PI-OHCA and decreased PI-STEMI following the stay-at-home order. The increased PI-OHCA was not fully explained by the reduction in PI-STEMI. Field defibrillation and return of spontaneous circulation were lower. It is critical that public health messaging stress that emergency care should not be delayed.

Introduction: Defibrillation is effective and the most common treatment for ventricular fibrillation (VF) and pulseless ventricular tachycardia in patients with cardiac arrest., Patient Concerns: Recently we experienced 3 cases refractory ventricular fibrillation (RVF) which was successfully terminated with double sequence defibrillation (DSD) in our emergency department, so we'd like to report and discuss it., Diagnosis: Cardiac arrest., Interventions: A single defibrillation 200J was performed twice for patients with ventricular fibrillation in the initial rhythm of the emergency room. At the same time, intubation and intravenous access were achieved and epinephrine and amiodarone were administered. The 400J DSD was performed on RVF patients with sustained VFs, despite several trials of 150-200J defibrillation and adherence to advanced cardiac life support., Outcomes: All three RVF patients recovered spontaneous circulation after DSD., Conclusion: The three cases we have shown are small, but DSD improves the chance of spontaneous circulation. Therefore it is suggested that attempts of DSD to patients with RVF, especially in the prehospital stages as a way to improve the return of spontaneous circulation., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2021 the Author(s). Published by Wolters Kluwer Health, Inc.)

: The role of early defibrillation has been well established as a pivotal ring of the chain of survival since the nineties. In the following years, the scientific evidences about the beneficial role of early defibrillation have grown, and most of all, it has been demonstrated that the main determinant of survival is the time of defibrillation more than the type of rescuer. Early lay defibrillation was shown to be more effective than delayed defibrillation by healthcare providers. Moreover, because of the ease of use of automated external defibrillators (AEDs), it has been shown that also untrained lay rescuers can safely use an AED leading the guidelines to encourage early defibrillation by untrained lay bystanders. Although strong evidence has demonstrated that an increase in AED use leads to an increase in out-of-hospital cardiac arrest (OHCA) survival, the rate of defibrillation by laypeople is quite variable worldwide and very low in some realities. Our review of the literature about lay defibrillation highlights that the AED is a life-saving device as simple and well tolerated as underused.

Sudden cardiac arrest (SCA) is the leading cause of exercise-related fatalities in athletes. A comprehensive emergency action plan (EAP) is critical to facilitate a rapid and effective response to a cardiac emergency. SCA should be suspected in any athlete that collapses suddenly and is unresponsive. All potential responders to a collapsed athlete should be trained in the recognition of SCA, cardiopulmonary resuscitation, and use of an automated external defibrillator (AED). AEDs should be accessible on-site at sporting venues with a target collapse to first shock interval of less than 3 min. Every school, club, and sporting organization that sponsors athletic activities should have a written EAP for SCA. An EAP coordinator should be designated to foster compliance with training, practice, and rehearsal of the EAP at least once annually. Some sports require special considerations for equipment removal or access to emergency services in geographically broad or water-based venues.

Background: Although schools are key places that conduct cardiopulmonary resuscitation (CPR) and public-access defibrillation (PAD) programs, out-of-hospital cardiac arrest (OHCA) in educational institutions is poorly understood. This study describes the characteristics and outcomes of such OHCAs.Methods and Results:Data for OHCAs of any cause occurring in educational institutions between 2013 and 2015 were extracted from the All-Japan Utstein Registry. Patient characteristics and outcomes were documented. Subjects were divided into 6 age groups (0-1, 2-5, 6-11, 12-14, 15-17, and ≥18 years). Among the 783 eligible OHCA patients, most received bystander CPR regardless of age, ranging from 73.9% in those aged ≥18 years to 90.0% in those aged 2-5 years. However, the proportion receiving PAD differed by age group, ranging from 2.9% in those aged 0-1 years to 66.7% in those aged 12-14 years. The proportion of patients with 1-month survival with favorable neurological outcome differed significantly by age group, being extremely low among patients aged 0-1 years (zero for OHCA of cardiac origin), but high among patients aged 6-11, 12-14, and 15-17 years (69.2%, 77.5%, and 70.0%, respectively) for OHCA of cardiac origin., Conclusions: The outcomes of OHCA occurring in educational institutions, where PAD is available, differed significantly by age.

Background: This study assessed whether the dissemination of public-access defibrillation (PAD) at the population level is associated with an increase in neurologically favorable outcomes among patients experiencing ventricular fibrillation (VF) in public vs. residential locations in Japan.Methods and Results:We enrolled adult patients with bystander-witnessed VF between 2013 and 2015. The primary outcome measure was 1-month neurologically favorable outcome defined by cerebral performance category 1 or 2. The number of survivors with neurologically favorable outcome attributed to PAD after VF arrest was estimated by location of arrest. A total of 16,252 adult patients with bystander-witnessed VF arrest were analyzed. In public locations, 29.3% (2,334/7,973) of out-of-hospital cardiac arrest (OHCA) patients received PAD, whereas 1.1% (89/8,279) of OHCA patients received PAD in residential locations. OHCA patients with PAD had significantly better neurological outcomes compared with those without PAD in public locations (51.8% vs. 25.5%, P<0.001), whereas there were no significant differences in neurologically favorable outcome between patients with or without PAD in residential locations (22.5% vs. 18.6%, P=0.357). The total number of patients with neurologically favorable outcomes attributed to PAD was estimated at 615 in public locations, but only 3 in residential locations., Conclusions: In Japan, when compared with residential locations, PAD works more successfully in public locations for adults with bystander-witnessed VF arrest.

Aims: We aimed to reveal the effects of application of public-access automated external defibrillators (AEDs) and bystander-initiated cardiopulmonary resuscitation (CPR) on survival of paediatric patients with out-of-hospital cardiac arrest (OHCA) occurring on school campuses in Japan., Methods and Results: Data were obtained from a nationwide prospective observational study of paediatric OHCAs in school settings in Japan, termed Stop and Prevent cardIac aRrest, Injury, and Trauma in Schools (SPIRITS). Non-traumatic OHCA patients from elementary school, junior high school, and high school/technical college between April 2008 and December 2015 were enrolled. A multivariable logistic regression analysis was conducted to assess the effect of bystander interventions (i.e. public-access AED application and bystander-CPR) on 30-day survival with favourable neurological outcome. In total, 232 OHCA cases were analysed. The proportion of 30-day survival with favourable neurological outcome was significantly higher among the patients receiving both public-access AED application and bystander-CPR than those without any bystander intervention (50.9% vs. 20.0%, adjusted odds ratio 4.08, 95% confidence interval 1.25-13.31; P = 0.020). During the study period, the proportion of patients to whom public-access AEDs were applied increased significantly (from 61.9% in 2008 to 87.0% in 2015, P-for trend = 0.014). Accordingly, the proportion of 30-day survival with favourable neurological outcome improved significantly (from 38.1% in 2005 to 56.5% in 2015, P-for trend = 0.026)., Conclusion: The combination of public-access AED application and bystander-CPR increased the chance of survival approximately four-fold in schools. The nationwide efforts towards disseminating public-access defibrillation systems in school settings may reduce the risk of sudden cardiac death among school children., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2018. For permissions, please email: journals.permissions@oup.com.)

Out-of-hospital sudden cardiac arrest (OHCA) is a major public health issue, with a survival rate at hospital discharge that remains below 10% in most cities, despite huge investments in this domain. Early basic life support (BLS) and early defibrillation using automated external defibrillators (AEDs) stand as key elements for improving OHCA survival rate. Nevertheless, the use of AEDs in OHCA remains low, for a variety of reasons, including the number, accessibility and ease of locating AEDs, as well as bystanders' awareness of BLS manœuvres and of the need to use AEDs. Several measures have been proposed to improve the rate of AED use, including optimization of AED deployment strategies as well as the use of drones to bring the AEDs to the OHCA scene and of mobile applications to locate the nearest AED. If they are to be effective, these measures should be combined with large communication campaigns on OHCA, and wide-scale education of the public in BLS and AEDs, to reduce the burden of OHCA., (Copyright © 2018 Elsevier Masson SAS. All rights reserved.)

Background: The quality of cardiopulmonary resuscitation (CPR) performed by emergency medical services (EMS) personnel affects patient outcomes after cardiac arrest. A CPR feedback device with an accelerometer mounted on a defibrillator can monitor the motion of the patient's sternum to display and record CPR quality in real time. To evaluate the utility of real-time feedback, debriefing, and retraining using a CPR feedback device outside of the hospital, an open-label, cluster randomized controlled trial will be conducted in five municipalities of Osaka Prefecture, Japan., Methods: Each EMS station within a fire department will be randomly assigned to: 1) the treatment group with real-time feedback, debriefing, and retraining using the CPR feedback device (intervention group); or 2) the conventional treatment group without real-time feedback, debriefing, and retraining (control group). This trial will include 2850 to 3020 patients over about 4 years. The primary outcome of the trial is 1-month favorable neurological survival, defined as cerebral performance category scale score 1 or 2. Secondary outcomes are 1-month survival, survival to hospital discharge, return of spontaneous circulation, and quality of CPR including fraction, depth, tempo, and ventilation rate., Discussion: The trial will assess whether treatment monitored by the CPR feedback device, which allows for real-time feedback, debriefing, and retraining using CPR quality data, outperforms conventional treatment without real-time feedback, debriefing, and retraining in terms of 1-month favorable neurological survival in cardiac arrest patients receiving CPR outside the hospital., Trial Registration: University Hospital Medical Information Network (UMIN) Clinical Trials Registry, UMIN000021431 . Registered on 11 March 2016.

Competing Interests: Competing interests: None declared.

Objective: Sudden cardiac arrest (SCA) is a rare but tragic event during amateur sports activities. Our aim is to analyse whether availability of automated external defibrillators (AEDs) in amateur sports centres could impact on SCA survival., Methods: This is an observational study. During an 18-year period, data regarding exercise-related SCA in sports centres were prospectively collected. Survival rates and time to response were compared between centres with an AED already available and centres where an AED was not already present., Results: Out of 252 sports facilities, 207 (82%) acquired an AED during follow-up while 45 (18%) did not. From 1999 to 2014, there were 26 SCAs (24 (92%) men, 54±17 years old) with 15 (58%) of them in centres with on-site AED. Neurologically intact survival rates were 93% in centres with on-site AED and 9% in centres without (P<0.001). Presence of on-site AED, presence of shockable rhythm, first assistance by a lay bystander and time to defibrillation were all related to neurological intact survival, but the presence of on-site AED was the only independent predictor in the multivariate analysis. The use of on-site AED resulted in a lower time to first shock when compared with emergency medical system-delivered AED (3.3±1.4min vs 7.3±3.2 min; P=0.001)., Conclusions: The presence of on-site AEDs is associated with neurologically intact survival after an exercise-related SCA. Continuous efforts are recommended in order to introduce AEDs in sports and fitness centres, implement educational programmes and increase common awareness about SCA., Competing Interests: Competing interests: None declared., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Introduction: Public access defibrillation doubles the chances of neurologically intact survival following out-of-hospital cardiac arrest (OHCA). Although there are increasing numbers of defibrillators (automated external defibrillator (AEDs)) available in the community, they are used infrequently, despite often being available. We aimed to match OHCAs with known AED locations in order to understand AED availability, the effects of reduced AED availability at night and the operational radius at which they can be effectively retrieved., Methods: All emergency calls to South Central Ambulance Service from April 2014 to April 2016 were screened to identify cardiac arrests. Each was mapped to the nearest AED, according to the time of day. Mapping software was used to calculate the actual walking distance for a bystander between each OHCA and respective AED, when travelling at a brisk walking speed (4 mph)., Results: 4012 cardiac arrests were identified and mapped to one of 2076 AEDs. All AEDs were available during daytime hours, but only 713 at night (34.3%). 5.91% of cardiac arrests were within a retrieval (walking) radius of 100 m during the day, falling to 1.59% out-of-hours. Distances to rural AEDs were greater than in urban areas (P<0.0001). An AED could potentially have been retrieved prior to actual ambulance arrival in 25.3% cases., Conclusion: Existing AEDs are underused; 36.4% of OHCAs are located within 500 m of an AED. Although more AEDs will improve availability, greater use can be made of existing AEDs, particularly by ensuring they are all available on a 24/7 basis., Competing Interests: Competing interests: CDD has received grants from the Resuscitation Council (UK) of which he is a member and is the ILCOR domain lead for ’Defibrillation'. All authors are employees of South Central Ambulance Service., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Aims: For patients surviving out-of-hospital cardiac arrest (OHCA) with a shockable rhythm, implantable cardioverter defibrillator (ICD) is recommended for non-reversible causes of arrest. We aimed to determine factors associated with implantation of ICD and survival in patients surviving non-AMI OHCA in a nationwide register covering all OHCAs in Denmark., Methods and Results: We identified 36 950 OHCAs between 2001 and 2012, 1700 of whom were ICD naïve, ≥18 years, of non-AMI cardiac aetiology and surviving until discharge. Six hundred fifty eight patients had ICD implanted during index admission. Association to ICD implantation during index admission was analysed in logistic regression, survival was assessed using Cox regression. Implantable cardioverter defibrillator implantation increased during the study period [odds ratio (OR) 1-year increase: 1.04, 95% confidence intervals (95% CI): 1.00-1.08, P = 0.03]. Non-shockable rhythm and age ≥70 years were associated with lower odds of ICD implantation (ORnon-shockable: 0.27, 95% CI: 0.19-0.37, P < 0.001, OR70-79 years: 0.71, 95% CI: 0.52-0.98, P = 0.04, OR≥80 years: 0.13, 95% CI: 0.07-0.22, P < 0.001). Non-AMI ischaemic heart disease, highest income tertile and chronic heart failure were associated with higher odds (ORIHD: 2.51, 95% CI: 1.77-3.60, P < 0.001, ORhighest income tertile: 1.58, 95% CI: 1.06-2.23, P = 0.02, ORHF: 1.77, 95% CI: 1.35-2.32, P < 0.001). Implantable cardioverter defibrillator implantation was associated with a lower risk of mortality (HR: 0.70, 95% CI: 0.53-0.92, P = 0.01)., Conclusion: Implantable cardioverter defibrillator implantation rates increased over the study period. CHF, previous IHD and high income were associated with ICD implantation, while older age and non-shockable rhythm was associated with lower odds of ICD implantation. Implantable cardioverter defibrillator implantation was associated with higher survival rates.

Objective: Comorbidity prior to out-of-hospital cardiac arrest (OHCA) and primary rhythm in relation to survival is not well established. We aimed to assess the prognostic importance of comorbidity in relation to primary rhythm in OHCA-patients treated with Target Temperature Management (TTM)., Design: Consecutive comatose survivors of OHCA treated with TTM in hospitals in the Copenhagen area between 2002-2011 were included. Utstein-based pre- and in-hospital data collection was performed. Data on comorbidity was obtained from The Danish National Patient Register and patient charts, assessed by the Charlson Comorbidity Index (CCI)., Results: A total of 666 patients were included. A third (n = 233, 35%) presented with non-shockable rhythm, and they were less often male (64% vs. 82%, p < .001), and OHCA in public, witnessed OHCA, and bystander cardiopulmonary resuscitation (CPR) were less common compared to patients with a shockable primary rhythm (public: 27% vs. 48%, p < .001, witnessed: 79% vs. 90%, p < .001, bystander CPR: 47% vs. 63%, p < .001). 30-day mortality was 62% compared to 28% in patients with non-shockable and shockable rhythm, respectively. By Cox-regression analyses, any comorbidity (CCI ≥1) was the only factor independently associated with 30-day mortality in patients with non-shockable rhythm (HR =1.9 (95% CI: 1.2-2.9), p < .01), whereas in patients with shockable rhythm comorbidity was not associated with outcome after adjustment for prognostic factors (HR = 0.82 (0.55-1.2), p = .34). No significant interaction between primary rhythm and comorbidity in terms of mortality was present., Conclusion: A higher comorbidity burden was independently associated with a higher 30-day mortality rate in patients presenting with non-shockable primary rhythm but not in patients with shockable rhythm.

The chain of survival aims to demonstrate the interrelationship between key stages of resuscitation and emphasises the need for all links to be effective in order to optimise the chances of survival. The contribution of each of the four links diminishes rapidly as patients succumb at each stage and the actual attrition rate results in rapidly decreasing numbers of patients progressing along the chain. This revised representation adjusts the area of each link in order to graphically represent the flow of patients through the chain. Greatest benefit in improving outcome will be achieved by focussing on improving care at links in the chain where there is the greatest number of patients., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Background: The response time of emergency medical services (EMS) is an important determinant of survival after out-of-hospital cardiac arrest. We sought to identify upper limits of EMS response times and bystander interventions associated with neurologically intact survival., Methods and Results: We analyzed the records of 553 426 patients with out-of-hospital cardiac arrest in a Japanese registry between 2010 and 2014. The primary study end point was 1-month neurologically intact survival (Cerebral Performance Category scale 1 or 2). Increased EMS response time was associated with significantly decreased adjusted odds of 1-month neurologically intact survival (adjusted odds ratio [aOR] for each 1-minute increase, 0.89; 95% confidence interval [CI], 0.89-0.90), although this relationship was modified by bystander interventions. The bystander interventions and the ranges of EMS response times that were associated with increased adjusted 1-month neurologically intact survival were as follows: bystander defibrillation, from ≤2 minutes (aOR, 3.10 [95% CI, 1.25-7.31]) to 13 minutes (aOR, 5.55 [95% CI, 2.66-11.2]); bystander conventional cardiopulmonary resuscitation, from 3 minutes (aOR 1.48 [95% CI, 1.02-2.12]) to 11 minutes (aOR 2.41 [95% CI, 1.61-3.56]); and bystander chest-compression-only cardiopulmonary resuscitation, from ≤2 minutes (aOR 1.57 [95% CI, 1.01-2.25]) to 11 minutes (aOR 1.92 [95% CI, 1.45-2.56]). However, the increase in neurologically intact survival of those receiving bystander interventions became statistically insignificant compared with no bystander interventions when the EMS response time was outside these ranges., Conclusions: The upper limits of the EMS response times associated with improved 1-month neurologically intact survival were 13 minutes when bystanders provided defibrillation (typically with cardiopulmonary resuscitation) and 11 minutes when bystanders provided cardiopulmonary resuscitation without defibrillation., (© 2018 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.)

Background: Out-of-hospital cardiac arrest (OHCA) commonly presents with nonshockable rhythms (asystole and pulseless electric activity). It is unknown whether antiarrhythmic drugs are safe and effective when nonshockable rhythms evolve to shockable rhythms (ventricular fibrillation/pulseless ventricular tachycardia [VF/VT]) during resuscitation., Methods: Adults with nontraumatic OHCA, vascular access, and VF/VT anytime after ≥1 shock(s) were prospectively randomized, double-blind, to receive amiodarone, lidocaine, or placebo by paramedics. Patients presenting with initial shock-refractory VF/VT were previously reported. The current study was a prespecified analysis in a separate cohort that initially presented with nonshockable OHCA and was randomized on subsequently developing shock-refractory VF/VT. The primary outcome was survival to hospital discharge. Secondary outcomes included discharge functional status and adverse drug-related effects., Results: Of 37 889 patients with OHCA, 3026 with initial VF/VT and 1063 with initial nonshockable-turned-shockable rhythms were treatment-eligible, were randomized, and received their assigned drug. Baseline characteristics among patients with nonshockable-turned-shockable rhythms were balanced across treatment arms, except that recipients of a placebo included fewer men and were less likely to receive bystander cardiopulmonary resuscitation. Active-drug recipients in this cohort required fewer shocks, supplemental doses of their assigned drug, and ancillary antiarrhythmic drugs than recipients of a placebo ( P <0.05). In all, 16 (4.1%) amiodarone, 11 (3.1%) lidocaine, and 6 (1.9%) placebo-treated patients survived to hospital discharge ( P =0.24). No significant interaction between treatment assignment and discharge survival occurred with the initiating OHCA rhythm (asystole, pulseless electric activity, or VF/VT). Survival in each of these categories was consistently higher with active drugs, although the trends were not statistically significant. Adjusted absolute differences (95% confidence interval) in survival from nonshockable-turned-shockable arrhythmias with amiodarone versus placebo were 2.3% (-0.3, 4.8), P =0.08, and for lidocaine versus placebo 1.2% (-1.1, 3.6), P =0.30. More than 50% of these survivors were functionally independent or required minimal assistance. Drug-related adverse effects were infrequent., Conclusions: Outcome from nonshockable-turned-shockable OHCA is poor but not invariably fatal. Although not statistically significant, point estimates for survival were greater after amiodarone or lidocaine than placebo, without increased risk of adverse effects or disability and consistent with previously observed favorable trends from treatment of initial shock-refractory VF/VT with these drugs. Together the findings may signal a clinical benefit that invites further investigation., Clinical Trial Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01401647., (© 2017 American Heart Association, Inc.)

Background Despite the positive effects of physical activity, the risk of sudden cardiac arrest is transiently increased during and immediately after exercise. The purpose of this study was to assess the incidence of exercise-related out-of-hospital cardiac arrest in the general population and to compare characteristics and prognosis of these cardiac arrests with non-exercise-related out-of-hospital cardiac arrests. Methods Data from all cases of treated out-of-hospital cardiac arrest outside of home reported to the Swedish Register of Cardiopulmonary Resuscitation from 2011-2015 in three counties of Sweden were investigated (population 2.1 m). This registry captures almost 100% of all out-of-hospital cardiac arrests in Sweden. Results Of 1825 out-of hospital cardiac arrests, 137 (7.5%) were exercise-related, resulting in an incidence of 1.2 per 100,000 person-years. The 30-day survival rate was significantly higher among exercise-related out-of hospital cardiac arrests compared to non-exercise-related out-of-hospital cardiac arrests (54.3 % vs 19.4%, p < 0.0001). Patients suffering an exercise-related out-of-hospital cardiac arrest were on average 10 years younger than those who had a non-exercise-related out-of-hospital cardiac arrest, 56.4 years compared to 67.2 years. Exercise-related out-of-hospital cardiac arrests were more often witnessed (89.4% vs 78.6%, p = 0.002), had higher rates of bystander cardiopulmonary resuscitation (80.3% vs 61.0%, p < 0.0001) and were more frequently connected to an automated external defibrillator (20.4% vs 4.6%, p < 0.0001). Conclusions Cardiac arrests that occur in relation to exercise have a significantly better prognosis and outcome than non-exercise-related cardiac arrests. This may be explained by favourable circumstances but may also reflect that these persons experience a sudden cardiac arrest at a lower degree of coronary artery disease, due to their younger age and to exercise being a trigger.

Background: The HeartRescue Project is a multistate public health initiative focused on establishing statewide out-of-hospital cardiac arrest (OHCA) systems of care to improve case capture and OHCA care in the community, by emergency medical services (EMS), and at hospital level., Methods and Results: From 2011 to 2015 in the 5 original HeartRescue states, all adults with EMS-treated OHCA due to a presumed cardiac cause were included. In an adult population of 32.8 million, a total of 64 988 OHCAs-including 10 046 patients with a bystander-witnessed OHCA with a shockable rhythm-were treated by 330 EMS agencies. From 2011 to 2015, the case-capture rate for all-rhythm OHCA increased from an estimated 39.0% (n=6762) to 89.2% (n=16 103; P <0.001 for trend). Overall survival to hospital discharge was 11.4% for all rhythms and 34.0% in the subgroup with bystander-witnessed OHCA with a shockable rhythm. We observed modest temporal increases in bystander cardiopulmonary resuscitation (41.8-43.5%, P <0.001 for trend) and bystander automated external defibrillator application (3.2-5.6%, P <0.001 for trend) in the all-rhythm group, although there were no temporal changes in survival. There were marked all-rhythm survival differences across the 5 states (8.0-16.1%, P <0.001) and across participating EMS agencies (2.7-26.5%, P <0.001)., Conclusions: In the initial 5 years, the HeartRescue Project developed a population-based OHCA registry and improved statewide case-capture rates and some processes of care, although there were no early temporal changes in survival. The observed survival variation across states and EMS systems presents a future challenge to elucidate the characteristics of high-performing systems with the goal of improving OHCA care and survival., (© 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.)

The European recommendations on cardiac arrest are based on the evidence gathered and reviewed by the International Resuscitation Liaison Committee (ILCOR) and were published in October 2015. These recommendations without representing a revolution, constitute an evolution centered on a primary goal to increase survival following cardiac arrest. This improvement in survival depends on four main factors: early identification of cardiac arrest, early access to rescue, early and quality CPR, and access to early defibrillation. These recommendations underline the importance of the interactions between the actors involved in the management of cardiac arrest: medical emergency dispatching personnel, the first provider who administers the CPR and the actors responsible for the deployment of public access defibrillation., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

Background: Although manual and semiautomatic external defibrillation (SAED) are commonly used in the management of out-of-hospital cardiac arrest, the optimal strategy is not known. We hypothesized that SAED would reduce the time to first shock and lead to higher rates of cardioversion and survival compared with a manual strategy., Methods and Results: Between July 2005 and June 2015, we included adult out-of-hospital cardiac arrest of presumed cardiac pathogenesis. On October 2012, a treatment protocol using SAED was introduced after years of manual defibrillation. The effect of the SAED implementation on the time to first shock, successful cardioversion, and patient outcomes was assessed using interrupted time series regression adjusting for arrest factors and temporal trend. Of the 14 776 cases, 10 224 (69.2%) and 4552 (30.8%) occurred during the manual and SAED protocols, respectively. Although the proportion of patients shocked within 2 minutes of arrival increased during the SAED protocol for initial shockable rhythms (from 58.9% to 69.2%; P <0.001), there was no difference in unadjusted rate of successful cardioversion after first shock (from 12.3% to 13.8%; P =0.13). After adjustment, the odds of delivering the first shock within 2 minutes of arrival increased under the SAED protocol (adjusted odds ratio [AOR], 1.72; 95% confidence interval [CI], 1.32-2.26; P <0.001). Despite this, the SAED protocol was associated with a reduction in survival to hospital discharge (AOR, 0.71; 95% CI, 0.55-0.92; P =0.009), event survival (AOR, 0.74; 95% CI, 0.62-0.88; P =0.001), and prehospital return of spontaneous circulation (AOR, 0.81; 95% CI, 0.68-0.96; P =0.01) when compared with the manual protocol. There was also no improvement in the rate of successful cardioversion after first shock (AOR, 0.73; 95% CI, 0.51-1.06; P =0.10)., Conclusions: Although SAED improved the time to first shock, this did not translate into higher rates of successful cardioversion or survival after out-of-hospital cardiac arrest. Advanced life support providers should be trained to use a manual defibrillation protocol., (© 2017 American Heart Association, Inc.)

Objective: Sudden cardiac arrest (SCA) in the young is a rare event but the effects can be devastating. We sought to identify variables that would lead to an improvement in time to defibrillation (TDFB), a previously noted factor significantly influencing survival from cardiac arrest., Design: During the 2013-2014 academic year, the Clark county school district performed quarterly drills to practice the coordinated automated external defibrillator (AED) response. Variables including school, AED carrier, and drill characteristics were measured to determine influence on TDFB. Schools were grouped by TDFB at a cutoff of three minutes. Characteristics were sought for schools with TDFB below three minutes. A mixed regression model taking into account repeated measures was created to determine which variables influenced TDFB., Results: Time to overhead announcement, distance of AED from drill site, and time to setup AED were the variables influencing TDFB with statistical significance (P <.01)., Conclusions: This study supports the notion of early recognition, announcement, and close proximity to an AED during a SCA to ensure an early TDFB. These results are consistent with basic life support and the chain of survival tenets of the American Heart Association., (© 2016 Wiley Periodicals, Inc.)

Background: Targeted automated external defibrillator (AED) programs have improved survival rates among patients who have an out-of-hospital cardiac arrest (OHCA) in US airports, as well as European and Japanese railways. The Sao Paulo (Brazil) Metro subway carries 4.5 million people per day. A targeted AED program was begun in the Sao Paulo Metro with the objective to improve survival from cardiac arrest., Methods and Results: A prospective, longitudinal, observational study of all cardiac arrests in the Sao Paulo Metro was performed from September 2006 through November 2012. This study focused on cardiac arrest by ventricular arrhythmias, and the primary endpoint was survival to hospital discharge with minimal neurological impairment. A total of 62 patients had an initial cardiac rhythm of ventricular fibrillation. Because no data on cardiac arrest treatment or outcomes existed before beginning this project, the first 16 months of the implementation was used as the initial experience and compared with the subsequent 5 years of full operation. Return of spontaneous circulation was not different between the initial 16 months and the subsequent 5 years (6 of 8 [75%] vs. 39 of 54 [72%]; P=0.88). However, survival to discharge was significantly different once the full program was instituted (0 of 8 vs. 23 of 54 [43%]; P=0.001)., Conclusions: Implementation of a targeted AED program in the Sao Paulo Metro subway system saved lives. A short interval between arrest and defibrillation was key for good long-term, neurologically intact survival. These results support strategic expansion of targeted AED programs in other large Latin American cities., (© 2015 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.)

Aim: Chest compression artefacts impede a reliable rhythm analysis during cardiopulmonary resuscitation (CPR). These artefacts are not present during ventilations in 30:2 CPR. The aim of this study is to prove that a fully automatic method for rhythm analysis during ventilation pauses in 30:2 CPR is reliable an accurate., Methods: For this study 1414min of 30:2 CPR from 135 out-of-hospital cardiac arrest cases were analysed. The data contained 1942 pauses in compressions longer than 3.5s. An automatic pause detector identified the pauses using the transthoracic impedance, and a shock advice algorithm (SAA) diagnosed the rhythm during the detected pauses. The SAA analysed 3-s of the ECG during each pause for an accurate shock/no-shock decision., Results: The sensitivity and PPV of the pause detector were 93.5% and 97.3%, respectively. The sensitivity and specificity of the SAA in the detected pauses were 93.8% (90% low CI, 90.0%) and 95.9% (90% low CI, 94.7%), respectively. Using the method, shocks would have been advanced in 97% of occasions. For patients in nonshockable rhythms, rhythm reassessment pauses would be avoided in 95.2% (95% CI, 91.6-98.8) of occasions, thus increasing the overall chest compression fraction (CCF)., Conclusion: An automatic method could be used to safely analyse the rhythm during ventilation pauses. This would contribute to an early detection of refibrillation, and to increase CCF in patients with nonshockable rhythms., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

Background: Guidelines recommend 2min of CPR after defibrillation attempts followed by ECG analysis during chest compression pause. This pause may reduce the likelihood of return of spontaneous circulation (ROSC) and survival. We have evaluated the possibility of analysing the rhythm earlier in the CPR cycle in an attempt to replace immediate pre-shock rhythm analysis., Methods and Results: The randomized Circulation Improving Resuscitation Care (CIRC) trial included patients with out of hospital cardiac arrest of presumed cardiac aetiology. Defibrillator data were used to categorize ECG rhythms as shockable or non-shockable 1min post-shock and immediately before next shock. ROSC was determined from end-tidal CO2, transthoracic impedance (TTI), and patient records. TTI was used to identify chest compressions. Artefact free ECGs were categorized during periods without chest compressions. Episodes without ECG or TTI data or with undeterminable ECG rhythm were excluded. Data were analyzed using descriptive statistics. Of 1657 patients who received 3409 analysable shocks, the rhythm was shockable in 1529 (44.9%) cases 1min post-shock, 13 (0.9%) of which were no longer shockable immediately prior to next possible shock. Of these, three had converted to asystole, seven to PEA and three to ROSC., Conclusion: While a shockable rhythm 1min post-shock was present also immediately before next possible defibrillation attempt in most cases, three patients had ROSC. Studies are needed to document if moving the pre-shock rhythm analysis will increase shocks delivered to organized rhythms, and if it will increase shock success and survival., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

A 40-year-old male struck his chest against a pole during a basketball game and had sudden out-of-hospital cardiac arrest. After bystander cardiopulmonary resuscitation, fire and emergency medical services personnel provided six defibrillation attempts prior to emergency department arrival. A 7th attempt in the emergency department using a different vector was unsuccessful. On the 8th attempt, using a second defibrillator with defibrillator pads placed adjacent to the primary set of defibrillator pads, two shocks were administered in near simultaneous fashion. The double sequential defibrillation was successful and the patient had return of spontaneous circulation at the next pulse check. He recovered in the intensive care unit, was discharged home 1 month later, and continues to follow up in clinic over 1 year later with a Cerebral Performance Category score of 1 (short-term memory deficits).

Background: Although increased dissemination of automated external defibrillators (AEDs) has been associated with more frequent AED use, the trade-off between the number of deployed AEDs and coverage of cardiac arrests remains unclear. We investigated how volunteer-based AED dissemination affected public cardiac arrest coverage in high- and low-risk areas., Methods and Results: All public cardiac arrests (1994-2011) and all registered AEDs (2007-2011) in Copenhagen, Denmark, were identified and geocoded. AED coverage of cardiac arrests was defined as historical arrests ≤100 m from an AED. High-risk areas were defined as those with ≥1 arrest every 2 years and accounted for 1.0% of the total city area. Of 1864 cardiac arrests, 18.0% (n=335) occurred in high-risk areas throughout the study period. From 2007 to 2011, the number of AEDs and the corresponding coverage of cardiac arrests increased from 36 to 552 and from 2.7% to 32.6%, respectively. The corresponding increase for high-risk areas was from 1 to 30 AEDs and coverage from 5.7% to 51.3%, respectively. Since the establishment of the AED network (2007-2011), few arrests (n=55) have occurred ≤100 m from an AED with only 14.5% (n=8) being defibrillated before the arrival of emergency medical services., Conclusions: Despite the lack of a coordinated public access defibrillation program, the number of AEDs increased 15-fold with a corresponding increase in cardiac arrest coverage from 2.7% to 32.6% over a 5-year period. The highest increase in coverage was observed in high-risk areas (from 5.7% to 51.3%). AED networks can be used as useful tools to optimize AED placement in community settings., (© 2014 American Heart Association, Inc.)

Introduction: The prognostic significance of conversion from nonshockable to shockable rhythms in patients with initial nonshockable rhythms who experience out-of-hospital cardiac arrest (OHCA) remains unclear. We hypothesized that the neurological outcomes in those patients would improve with subsequent shock delivery following conversion to shockable rhythms and that the time from initiation of cardiopulmonary resuscitation by emergency medical services personnel to the first defibrillation (shock delivery time) would influence those outcomes., Methods: We analyzed the data of 569,937 OHCA adults with initial nonshockable rhythms. The data were collected in a nationwide Utstein-style Japanese database between 2005 and 2010. Patients were divided into subsequently shocked (n =21,944) and subsequently not-shocked (n =547,993) cohorts. The primary study endpoint was 1-month favorable neurological outcome (Cerebral Performance Categories scale, category 1 or 2)., Results: In the subsequently shocked cohort, the ratio of 1-month favorable neurological outcome was significantly higher than that in the subsequently not-shocked cohort (1.79% versus 0.60%, P <0.001). Multivariate logistic regression analysis for 11 prehospital variables revealed that when the shock delivery time was less than 20 minutes, subsequent shock delivery was significantly associated with increased odds of 1-month favorable neurological outcomes (adjusted odds ratios (95% confidence interval), 6.55 (5.21 to 8.22) and 2.97 (2.58 to 3.43) for shock delivery times less than 10 minutes and from 10 to 19 minutes, respectively). However, when the shock delivery time was more than or equal to 20 minutes, subsequent shock delivery was not associated with increased odds of 1-month favorable neurological outcomes., Conclusions: In patients with an initial nonshockable rhythm after OHCA, subsequent conversion to shockable rhythms during emergency medical services resuscitation efforts was associated with increased odds of 1-month favorable neurological outcomes when the shock delivery time was less than 20 minutes.

Background: Prior investigation of out-of-hospital cardiac arrest has raised the concern that ventricular fibrillation (VF) recurrence may be triggered by chest compression (CC) resumption. We investigated predictors of VF recurrence after defibrillation, including timing of CC resumption., Methods and Results: Patients with witnessed out-of-hospital cardiac arrest and initial rhythm of VF from an Utstein-style database were analyzed. For each shock that defibrillated VF, CC resumption and VF recurrence times were determined. Shocks were classified according to postshock rhythm. Factors (age, sex, time from dispatch to monitor/defibrillator application, and CC resumption) that could predict VF recurrence were analyzed. CC resumption was categorized into groups: CC1, 1 to 5 seconds; CC2, 6 to 10 seconds; CC3, 11 to 30 seconds; and CC4, >30 seconds. Eighty-eight subjects were analyzed, with a total of 285 shocks, with 226 shocks that achieved asystole (n=102), organized rhythm (n=120), or monomorphic ventricular tachycardia (n=4). After a successful shock, CC resumption occurred at a median (interquartile range) of 8 (5-18) seconds. VF recurred after 166 shocks (74%) and recurred within 30 seconds in 69 shocks. There was no significant relationship between VF recurrence and factors analyzed including CC resumption time, nor stratified by postshock rhythm. The hazard ratios (HRs) for VF recurrence within 30 seconds for later CC groups (CC2, CC3, and CC4) relative to early CC resumption (CC1) were as follows: HR(CC2)=1.05 (P=0.9); HR(CC3)=1.75 (P=0.1); and HR(CC4)=0.67 (P=0.4)., Conclusions: VF recurrence within 30 seconds of a defibrillatory shock was not dependent on timing of CC resumption in patients with witnessed arrest and initial rhythm of VF., (© 2014 American Heart Association, Inc.)

Background: The strategy to place public-access automated external defibrillators (AEDs) has not yet been established in real settings., Methods and Results: This, prospective, population-based observational study in Osaka, Japan, included consecutive out-of-hospital cardiac arrest (OHCA) patients with resuscitation attempts during 7 years, from January 2005 through December 2011. The trends in the proportion of public-access AED use and 1-month survival with neurologically favorable outcome were evaluated by location. Factors associated with neurologically favorable outcome (defined as cerebral performance category 1 or 2) after ventricular fibrillation were also assessed using multiple logistic regression analysis. A total of 9453 bystander-witnessed OHCAs of cardiac origin were documented and 894 (9.5%) of them occurred at public places. The proportion of public-access AED use significantly increased from 0.0% (0/20) in 2005 to 41.2% (7/17) in 2011 at railway stations and from 0.0% (0/7) to 56.5% (13/23) at sports facilities. Mean time from collapse to shock was 5.0 minutes among those who received shocks with public-access AEDs. The proportion of neurologically favorable outcome was 28.0% (33/118) at railway stations, 51.6% (48/93) at sports facilities, 23.3% (20/86) in public buildings, and 41.9% (13/31) in schools. In multivariate analysis, early defibrillation, irrespective of bystander or emergency medical service (EMS) personnel, was significantly associated with neurologically favorable outcome (adjusted odds ratio for 1-minute increment, 0.89; 95% confidence interval, 0.87 to 0.92)., Conclusions: This large, population-based OHCA registry demonstrated that earlier shock, irrespective the shock provider (bystander or EMS personnel), contributed to improving outcome, and a public-access defibrillation program was successfully implemented so that shocks with public-access AEDs were delivered to over 40% of bystander-witnessed OHCAs and time to shock was shortened in some kinds of public places.

Background: Non-shockable arrest rhythms (pulseless electrical activity and asystole) represent an increasing proportion of reported cases of out-of-hospital cardiac arrest (OHCA). The prognostic significance of conversion from non-shockable to shockable rhythms during the course of resuscitation remains unclear., Objective: To evaluate whether out-of-hospital cardiac arrest survival with initially non-shockable arrest rhythms is improved with subsequent conversion to shockable rhythms., Methods: Secondary analysis of data in Epistry - Cardiac Arrest, an epidemiologic registry maintained by the Resuscitation Outcomes Consortium (ROC). This analysis includes OHCA events from December 1, 2005 through May 31, 2007 contributed by six US and two Canadian sites. For all EMS-treated adult (18 and older) cardiac arrest patients who presented with non-shockable cardiac arrest, we compared survival to hospital discharge between patients who did develop a shockable rhythm and those who did not based on receipt of subsequent defibrillation. Missing data were handled using multiple imputation. Multivariable logistic regression was used to adjust for potentially confounding variables., Results: A total of 6556 EMS treated adult cardiac arrest cases presented in non-shockable rhythms. Survival to discharge in patients who converted to a shockable rhythm was 2.77% while survival in those who did not was 2.72% (p=0.92). After adjusting for confounders, conversion to a shockable rhythm was not associated with improved survival (OR 0.88, 95% CI: 0.60-1.30)., Conclusion: For OHCA patients presenting in PEA/asystole, survival to hospital discharge was not associated with conversion to a shockable rhythm during EMS resuscitation efforts., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

Introduction: Prompt recognition of cardiac arrest and initiation of cardiopulmonary resuscitation (CPR) and defibrillation is necessary for good outcomes from out-of-hospital cardiac arrest (OHCA). This study aims to describe the recognition and treatment of OHCA in patients conveyed by non-emergency ambulance services (EAS) in Singapore., Materials and Methods: This is a multi-centre, retrospective chart review, of cases presenting to public emergency departments (EDs), conveyed by non-EAS and found to be in cardiac arrest upon ED arrival. The study was from October 2002 to August 2009. The following variables were examined: ability to recognise cardiac arrest, whether CPR was carried out by the ambulance crew and whether an automated external defibrillator (AED) was applied., Results: Eighty-six patients were conveyed by non-EAS and found to be in cardiac arrest upon ED arrival. Mean age was 63 years (SD 21.8), 70.9% were males. A total of 53.5% of arrests occurred in the ambulance while 70.9% were found to be asystolic upon ED arrival. Seven patients had a known terminal illness. Survival to discharge was 3.5%. Cardiac arrest went unrecognised by the ambulance crew in 38 patients (44.2%). CPR was performed in 35 patients (40.7%) of the 86 patients and AED was applied in only 10 patients (11.6%)., Conclusion: We found inadequate recognition and delayed initiation of treatment for OHCA. Possible reasons include a lack of training in patient monitoring and detection of cardiac arrest, lack of CPR training, lack of confidence in performing CPR, lack of AEDs on ambulances and lack of training in their use.

Background: The LUCAS™ device delivers mechanical chest compressions that have been shown in experimental studies to improve perfusion pressures to the brain and heart as well as augmenting cerebral blood flow and end tidal CO2, compared with results from standard manual cardiopulmonary resuscitation (CPR). Two randomised pilot studies in out-of-hospital cardiac arrest patients have not shown improved outcome when compared with manual CPR. There remains evidence from small case series that the device can be potentially beneficial compared with manual chest compressions in specific situations. This multicentre study is designed to evaluate the efficacy and safety of mechanical chest compressions with the LUCAS™ device whilst allowing defibrillation during on-going CPR, and comparing the results with those of conventional resuscitation., Methods/design: This article describes the design and protocol of the LINC-study which is a randomised controlled multicentre study of 2500 out-of-hospital cardiac arrest patients. The study has been registered at ClinicalTrials.gov (http://clinicaltrials.gov/ct2/show/NCT00609778?term=LINC&rank=1)., Results: Primary endpoint is four-hour survival after successful restoration of spontaneous circulation. The safety aspect is being evaluated by post mortem examinations in 300 patients that may reflect injuries from CPR., Conclusion: This large multicentre study will contribute to the evaluation of mechanical chest compression in CPR and specifically to the efficacy and safety of the LUCAS™ device when used in association with defibrillation during on-going CPR.

Background: The use and popularity of the biphasic waveform defibrillator as a replacement for the monophasic waveform defibrillator are increasing, but it is unclear whether this can improve the rate of survival among out-of-hospital cardiac arrest patients. This study aimed to verify the hypothesis that the outcome of out-of-hospital cardiac arrest patients who received defibrillation shock with the biphasic waveform defibrillator was better than that of patients who received defibrillation shock with the monophasic defibrillator., Methods and Results: This prospective, nationwide, population-based, observational study included 21 172 out-of-hospital cardiac arrest patients with initial ventricular fibrillation or pulseless ventricular tachycardia from January 1, 2005, through December 31, 2007. Defibrillation shock was performed by monophasic defibrillator on 8224 (39%) patients and by biphasic defibrillator on 12 948 (61%) patients. The rate of survival at 1 month with minimal neurological impairment was 11.6% (951/8192) in the monophasic defibrillator group and 12.8% (1653/12 928) in the biphasic defibrillator group. Hierarchical logistic regression analysis using a generalized estimation equation showed no significant difference between the biphasic and monophasic groups in 1-month survival with minimal neurological impairment (adjusted odds ratio, 1.07; 95% confidence interval, 0.91-1.26; P=0.42). Confirmatory propensity score analyses showed similar results., Conclusions: Although monophasic defibrillators are being replaced by biphasic defibrillators, our nationwide population-based observational study failed to demonstrate a statistically significant association between defibrillation waveform and 1-month survival rate with minimal neurological impairment.

Objective: Indexes such as amplitude spectrum area (AMSA) and power spectrum area (PSA) obtained from electrocardiogram waveform analysis are possible predictors of outcome after electrical defibrillation for ventricular fibrillation (VF). In this study, we examined AMSA and PSA to determine whether these parameters can predict defibrillation outcome., Materials and Methods: A total of 83 out-of-hospital VF victims were classified into four groups according to type of cardiac rhythm after shock: return of spontaneous circulation (ROSC), VF, pulseless electrical activity (PEA), and asystole. AMSA and PSA were calculated from electrocardiograms prior to shock and compared between groups., Results: The mean AMSA (4.0-48 Hz) in the ROSC group was 24.2 ± 8.5 mV-Hz, which was significantly higher than that in the VF and asystole groups., Conclusion: It is possible by analyzing the AMSA of VF to predict cases where electrical defibrillation is more likely to return cardiac rhythm. Furthermore, unnecessary electrical shocks with a low possibility of ROSC can be avoided, and chest compression should be continued to prevent myocardial damage and consequently improve prognosis.

Background: Perishock pauses are pauses in chest compressions before and after defibrillatory shock. We examined the relationship between perishock pauses and survival to hospital discharge., Methods and Results: We included out-of-hospital cardiac arrest patients in the Resuscitation Outcomes Consortium Epistry-Cardiac Arrest who suffered arrest between December 2005 and June 2007, presented with a shockable rhythm (ventricular fibrillation or pulseless ventricular tachycardia), and had cardiopulmonary resuscitation process data for at least 1 shock (n=815). We used multivariable logistic regression to determine the association between survival and perishock pauses. In an analysis adjusted for Utstein predictors of survival, the odds of survival were significantly lower for patients with preshock pause ≥20 seconds (odds ratio, 0.47; 95% confidence interval, 0.27 to 0.82) and perishock pause ≥40 seconds (odds ratio, 0.54; 95% confidence interval, 0.31 to 0.97) compared with patients with preshock pause <10 seconds and perishock pause <20 seconds. Postshock pause was not independently associated with a significant change in the odds of survival. Log-linear modeling depicted a decrease in survival to hospital discharge of 18% and 14% for every 5-second increase in both preshock and perishock pause interval (up to 40 and 50 seconds, respectively), with no significant association noted with changes in the postshock pause interval., Conclusions: In patients with cardiac arrest presenting in a shockable rhythm, longer perishock and preshock pauses were independently associated with a decrease in survival to hospital discharge. The impact of preshock pause on survival suggests that refinement of automatic defibrillator software and paramedic education to minimize preshock pause delays may have a significant impact on survival.