Part 6: Electrical Therapies

Part 6: Defibrillation

Resuscitation highlights in 2011

Two-thirds of deaths from coronary disease occur in the pre-hospital phase and are caused by ventricular fibrillation or pulseless ventricular tachycardia, for which electrical defibrillation is the only effective treatment. The time delay between the onset of ventricular fibrillation and the administration of the first defibrillatory shock is the most important determinant for survival. To achieve the earliest defibrillation possible, rescuers others than physicians need to be able to initiate this treatment. The international scientific community strongly supports the concept of early defibrillation in the setting of a strong chain of survival. New technological developments of automated external defibrillators (AEDs) allowed the implementation of defibrillation by the first responding professional rescuer. As a consequence of the technological evolution in implantable defibrillators, much research has also been done on new defibrillation waveforms and alternative energy levels in external defibrillators. After initial animal research, human clinical investigation has shown that initial low energy (150J) nonprogressive (150J-150J-150J) impedance-adjusted biphasic waveform defibrillatory shocks for patients in out-of-hospital ventricular fibrillation are safe, acceptable and clinically effective. Reporting on outcome from cardiac arrest must be as uniform as possible to allow conclusions on performance of emergency medical service systems. The 'Utstein Style' nomenclature is a glossary of terms and a reporting guideline for uniform description of cardiac arrest, resuscitation, the emergency medical service (EMS) system and the outcome. Reports on experiences with AED programmes by traditional and non-traditional professional rescuers support the view that AEDs should not be implemented in EMS systems as an isolated intervention, but that efforts are equally needed to strengthen the other links of the chain of survival. The international scientific community (American Heart Association, International Liaison Committee on Resuscitation and European Resuscitation Council) have issued guidelines for the use of AEDs by EMS providers and first responders, and a universal treatment algorithm is proposed.

Implementação do Programa Nacional de Desfibrilhação Automática Externa em Portugal

Objectives: After activating 9-1-1 for out-of-hospital cardiac arrest (CA), guidelines for children 1 year and older have evolved to include immediate automated external defibrillator (AED) use for witnessed arrest, and two minutes of cardiopulmonary resuscitation (CPR) followed by AED use for unwitnessed arrests. The best approach to resuscitation in a two-tiered emergency medical services (EMS) system depends in part on how likely the patient is to present with ventricular fibrillation (VF). Therefore, the authors evaluated the frequency of VF with respect to age and other characteristics to further elucidate the role of the AED among pediatric CAs. Methods: The investigation was a retrospective cohort study of EMS-treated, nontraumatic, out-of-hospital CA among persons aged 1–18 years in King County, Washington, between April 1, 1976, and December 31, 2003. The primary goal was to identify the proportion of patients presenting to EMS in VF, according to age. The association between other characteristics and the likelihood of VF was also evaluated. Finally, hospital survival according to cardiac rhythm at EMS arrival was evaluated. Results: Ventricular fibrillation was the presenting rhythm in 17.6% of cases (48/272). The proportion presenting with VF was 7.6% (10/131) among children aged 1–7 years and 27.0% (38/141) among children aged 8–18 years (p < 0.001). In multivariable models, VF was independently associated with age 8 years and older compared with 1–7 years (odds ratio, 3.19; 95% confidence interval [CI] = 1.46 to 6.97), witnessed arrest (odds ratio, 3.33; 95% CI = 1.63 to 6.82), and cardiac etiology (odds ratio, 2.89; 95% CI = 1.32 to 6.34). Survival was 31.3% (15/48) for VF and 10.7% (24/224) for nonshockable rhythm CAs. Conclusions: The proportion of children aged younger than 8 years presenting with VF is low compared with older children. The greatest increase in VF proportion occurs in children older than 12 years. Based on these results, the best approach for initial EMS resuscitation in a two-tiered EMS system, CPR versus AED use, is uncertain among younger children. Inclusion of witness status into the decision process for younger children may more efficiently allocate AED use, a finding in accordance with 2005 guidelines.

Survival after Public Access Defibrillation in Stockholm, Sweden – A striking success

The potential risk of inducing ventricular arrhythmias was explored by employing pulsed field ablation (PFA) through the administration of both monophasic and biphasic waveform deliveries. PFA was applied to specific locations in the right ventricle (RV, n = 5 sites) in swine (n = 2), utilizing identical settings with consistent amplitude, pulse width, and a number of pulses for both monophasic and biphasic waveforms. PFA deliveries were precisely timed in 10-ms intervals across the entire T wave. Using monophasic waveforms, ventricular fibrillation (VF) was induced 7/7 times when PFA pulses were delivered during the T wave. Biphasic waveforms resulted in no ventricular arrhythmias when PFA was delivered across the entire duration of T wave. Our findings indicate that VF can be consistently induced with monophasic pulse waveforms, but not with biphasic pulse waveforms in a porcine model.

In the present study, we compared an automatic external defibrillator (AED) that delivers 150-J biphasic shocks with traditional high-energy (200- to 360-J) monophasic AEDs. AEDs were prospectively randomized according to defibrillation waveform on a daily basis in 4 emergency medical services systems. Defibrillation efficacy, survival to hospital admission and discharge, return of spontaneous circulation, and neurological status at discharge (cerebral performance category) were compared. Of 338 patients with out-of-hospital cardiac arrest, 115 had a cardiac etiology, presented with ventricular fibrillation, and were shocked with an AED. The time from the emergency call to the first shock was 8.9+/-3.0 (mean+/-SD) minutes. The 150-J biphasic waveform defibrillated at higher rates, resulting in more patients who achieved a return of spontaneous circulation. Although survival rates to hospital admission and discharge did not differ, discharged patients who had been resuscitated with biphasic shocks were more likely to have good cerebral performance.

Automated external defibrillators (AEDs) have the potential to save lives when used during cardiac arrest. While most cardiac arrests occur at home, there is limited evidence for AED use in private homes. To determine whether AEDs in private homes are effective and cost-effective. This cohort study used observational data from the Cardiac Arrest Registry to Enhance Survival in the US from January 2017 to December 2024 to determine the effectiveness of AEDs when used for cardiac arrests in private homes. A difference-in-difference approach was used to determine the causal relationship between AED application and survival to hospital discharge. A decision-analytic model was then created to evaluate the cost-effectiveness of purchasing an AED in a private home in the US. Application of an AED. Survival to hospital discharge and cost-effectiveness. Of 582 536 included patients, 359 809 (61.8%) were male, and the median (IQR) age was 65 (52-76) years. Survival was better with AED application compared with no AED application in patients with a shockable rhythm (risk ratio, 1.26; 95% CI, 1.01-1.57) but not in those with a nonshockable rhythm (risk ratio, 1.00; 95% CI, 0.68-1.46). Results were consistent in the difference-in-difference analysis. The incremental cost-effectiveness ratio for an AED in a private home was $4 481 659 per quality-adjusted life-year. At a cost-effectiveness threshold of $200 000 per quality-adjusted life-year, AEDs in private homes would be considered cost-effective at a yearly cardiac arrest incidence per person above 1.3% or at an AED cost less than $65 (not including bystander training cost). In this study, AEDs in private homes were effective at improving outcomes for patients with cardiac arrest and a shockable rhythm. Given the relative rarity of cardiac arrest at a given home, general purchase of AEDs for individual private homes cannot be considered cost-effective at the current pricing of AEDs.

Introduction: Ventricular fibrillation (VF) is the most common arrhythmia causing out-of-hospital cardiac arrest (OOHCA) and defibrillation remains the mainstay of its treatment. Successful defibrillation is linked to VF morphology characteristics, and is affected by VF duration, quality of cardiopulmonary resuscitation (CPR) and emergency medical service (EMS) responsiveness. This study aimed at comparing VF morphology characteristics and their relationships with patients and EMS characteristics, as well as outcomes, in an Asian community. Method: Electrocardiographic recordings of VF signals from automated external defibrillators (AEDs) in 2008 to 2012 were obtained from OOHCA subjects in Taipei city, a metropolitan with 2.65 million residents in 272km2. Amplitude spectrum analysis (AMSA) and DFAα2 were calculated and compared year by year in the study period. Results: A total of 612 OOHCA subjects with VF were included for analysis. Both DFA and AMSA changed significantly over time (χ 2 for trend: -0.128 for DFA, p&lt;0.01; 0.092 for AMSA, p=0.02). There was no change in gender, age, and bystander CPR rates; however, in later years there were more witnessed arrests, shortened EMS responses, and better sustained (&gt;2 hr) return of spontaneous circulation (ROSC) and neurological outcomes (CPC 1&amp;2). The time trend for DFAα2 (OR 0.98, CI 0.96-0.99, p=0.003), but not for AMSA (OR 1.07, CI 0.99-1.14), remained after adjustment for confounders. Both DFAα2 and AMSA were associated with sustained ROSC (DFA OR 0.08, CI 0.04-0.18, p&lt;0.001; AMSA OR 1.18, CI 1.01-1.38, p=0.03) and CPC 1&amp;2 (DFA OR 0.04, CI 0.01-0.16, p&lt;0.001; AMSA OR 1.30, CI 1.07-1.57, p=0.008) in multiple regression models. Conclusions: DFAα2 and AMSA, two important VF characteristics, changed significantly over time in an Asian community, and were associated with improved outcomes. This might reflect improvement in community chain of survival especially among EMS responses and community quality of CPR.

Experience with the use of automated external defibrillators in out of hospital cardiac arrest

312: Out-of-hospital cardiac arrest: use of automated external defibrillators and in-hospital death

AP-452680-2 GEOSPATIAL ANALYSIS OF BYSTANDER-INITIATED AUTOMATED EXTERNAL DEFIBRILLATOR UTILIZATION IN A LARGE US COMMUNITY

a fire erupted in a large retail store and no attempt was made by the employees to quench the still small fire because fire extinguisher use was restricted to trained firefighters only?Or, some state laws protected only fire department-trained responders from potential liability?Or, owning a fire extinguisher brought with it a concomitant requirement for fire department supervision?And what if every state had a different law?Although these scenarios seem preposterous, they do accurately reflect the current environment in the United States for automated external defibrillators (AEDs).Despite the intuitive design of modern AEDs, and the clear relationship between sudden cardiac arrest (SCA) survival and time to defibrillation, AEDs are not extensively disseminated in public places.In this report, we describe how disparate state laws impede AED adoption, and we present a blueprint for a national legislative initiative to facilitate widely accessible public access defibrillation.

Hundreds of school and community-based rugby teams around Japan come to Sugadaira, Nagano, during the summer months for training camps. The area is rural and sparsely populated, with an average emergency medical service response time of 30 minutes. Only 4 of 108 athletic fields in Sugadaira had access to an automated external defibrillator (AED), which posed a significant challenge to the emergency response in the area. In 2021, a student-athlete experiencing cardiopulmonary arrest was successfully resuscitated, attributed to the event occurring at one of the four fields equipped with an AED. PURPOSE: Propose a community-based AED program to enhance sports medicine and emergency response in a rural town in Japan during the period of over-tourism by school-organized rugby training camp users. METHOD: The Sugadaira AED for Everyone (SAFE) project, conducted from 2022 - 2024, prepared and made available 274 (2022, n = 105; 2023, n = 86; 2024, n = 83) portable AEDs during the respective rugby training camp seasons in 2022 (7/8-9/5), 2023 (7/13-9/11), and 2024 (7/12-9/9). AEDs were made available through the support of the Japan Rugby Football Union (JRFU funded costs during 2022 - 2023 season) and the local athletic field union (funded 50% along with JRFU [50% match]) during 2024 season. A cost analysis of the AED rental fee was conducted to assess its sustainability. RESULT: AEDs were accessible to 595, 878, and 909 teams in 2022, 2023, and 2024, respectively. No cardiopulmonary arrest cases were documented during the study period. The total cost of supporting the portables AEDs to be made available onsite was 4,383,000 yen, with an average cost of 1951 ± 758 yen per team per training camp stay. CONCLUSION: This case study provides valuable insights for establishing a community-based sports medicine framework in rural regions with pre-identified high-demand seasons. Although the SAFE program was fully funded by the JRFU and local athletic field union during the study period, our findings indicate that the associated costs could be feasibly distributed among teams staying in Sugadaira with minimal financial impact. The current cost analysis may support the implementation of a sustainable per capita infrastructure fee to enhance emergency preparedness in Sugadaira that does not rely on unsecured funding from organizations. Supported by: The project was funded by Japan Rugby Football Union.