2023 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations: Summary From the Basic Life Support; Advanced Life Support; Pediatric Life Support; Neonatal Life Support; Education, Implementation, and Teams; and First Aid Task Forces.

The International Liaison Committee on Resuscitation engages in a continuous review of new, peer-reviewed, published cardiopulmonary resuscitation and first aid science. Draft Consensus on Science With Treatment Recommendations are posted online throughout the year, and this annual summary provides more concise versions of the final Consensus on Science With Treatment Recommendations from all task forces for the year. Topics addressed by systematic reviews this year include resuscitation of cardiac arrest from drowning, extracorporeal cardiopulmonary resuscitation for adults and children, calcium during cardiac arrest, double sequential defibrillation, neuroprognostication after cardiac arrest for adults and children, maintaining normal temperature after preterm birth, heart rate monitoring methods for diagnostics in neonates, detection of exhaled carbon dioxide in neonates, family presence during resuscitation of adults, and a stepwise approach to resuscitation skills training. Members from 6 International Liaison Committee on Resuscitation task forces have assessed, discussed, and debated the quality of the evidence, using Grading of Recommendations Assessment, Development, and Evaluation criteria, and their statements include consensus treatment recommendations. Insights into the deliberations of the task forces are provided in the Justification and Evidence-to-Decision Framework Highlights sections. In addition, the task forces list priority knowledge gaps for further research. Additional topics are addressed with scoping reviews and evidence updates.

Inappropriate Shock Delivery Is Common During Pediatric In-Hospital Cardiac Arrest.

OBJECTIVES: To characterize inappropriate shock delivery during pediatric in-hospital cardiac arrest (IHCA). DESIGN: Retrospective cohort study. SETTING: An international pediatric cardiac arrest quality improvement collaborative Pediatric Resuscitation Quality [pediRES-Q]. PATIENTS: All IHCA events from 2015 to 2020 from the pediRES-Q Collaborative for which shock and electrocardiogram waveform data were available. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We analyzed 418 shocks delivered during 159 cardiac arrest events, with 381 shocks during 158 events at 28 sites remaining after excluding undecipherable rhythms. We classified shocks as: 1) appropriate (ventricular fibrillation [VF] or wide complex ≥ 150/min); 2) indeterminate (narrow complex ≥ 150/min or wide complex 100-149/min); or 3) inappropriate (asystole, sinus, narrow complex < 150/min, or wide complex < 100/min) based on the rhythm immediately preceding shock delivery. Of delivered shocks, 57% were delivered appropriately for VF or wide complex rhythms with a rate greater than or equal to 150/min. Thirteen percent were classified as indeterminate. Thirty percent were delivered inappropriately for asystole (6.8%), sinus (3.1%), narrow complex less than 150/min (11%), or wide complex less than 100/min (8.9%) rhythms. Eighty-eight percent of all shocks were delivered in ICUs or emergency departments, and 30% of those were delivered inappropriately. CONCLUSIONS: The rate of inappropriate shock delivery for pediatric IHCA in this international cohort is at least 30%, with 23% delivered to an organized electrical rhythm, identifying opportunity for improvement in rhythm identification training.

Pediatric Life Support: 2020 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations.

This 2020 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations (CoSTR) for pediatric life support is based on the most extensive evidence evaluation ever performed by the Pediatric Life Support Task Force. Three types of evidence evaluation were used in this review: systematic reviews, scoping reviews, and evidence updates. Per agreement with the evidence evaluation recommendations of the International Liaison Committee on Resuscitation, only systematic reviews could result in a new or revised treatment recommendation. Systematic reviews performed for this 2020 CoSTR for pediatric life support included the topics of sequencing of airway-breaths-compressions versus compressions-airway-breaths in the delivery of pediatric basic life support, the initial timing and dose intervals for epinephrine administration during resuscitation, and the targets for oxygen and carbon dioxide levels in pediatric patients after return of spontaneous circulation. The most controversial topics included the initial timing and dose intervals of epinephrine administration (new treatment recommendations were made) and the administration of fluid for infants and children with septic shock (this latter topic was evaluated by evidence update). All evidence reviews identified the paucity of pediatric data and the need for more research involving resuscitation of infants and children.

Code Team Structure and Training in the Pediatric Resuscitation Quality International Collaborative.

OBJECTIVES: Code team structure and training for pediatric in-hospital cardiac arrest are variable. There are no data on the optimal structure of a resuscitation team. The objective of this study is to characterize the structure and training of pediatric code teams in sites participating in the Pediatric Resuscitation Quality Collaborative. METHODS: From May to July 2017, an anonymous voluntary survey was distributed to 18 sites in the international Pediatric Resuscitation Quality Collaborative. The survey content was developed by the study investigators and iteratively adapted by consensus. Descriptive statistics were calculated. RESULTS: All sites have a designated code team and hospital-wide code team activation system. Code team composition varies greatly across sites, with teams consisting of 3 to 17 members. Preassigned roles for code team members before the event occur at 78% of sites. A step stool and backboard are used during resuscitations in 89% of surveyed sites. Cardiopulmonary resuscitation (CPR) feedback is used by 72% of the sites. Of those sites that use CPR feedback, all use an audiovisual feedback device incorporated into the defibrillator and 54% use a CPR coach. Multidisciplinary and simulation-based code team training is conducted by 67% of institutions. CONCLUSIONS: Code team structure, equipment, and training vary widely in a survey of international children's hospitals. The variations in team composition, role assignments, equipment, and training described in this article will be used to facilitate future studies regarding the impact of structure and training of code teams on team performance and patient outcomes.

2019 American Heart Association Focused Update on Pediatric Advanced Life Support: An Update to the American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.

This 2019 focused update to the American Heart Association pediatric advanced life support guidelines follows the 2018 and 2019 systematic reviews performed by the Pediatric Life Support Task Force of the International Liaison Committee on Resuscitation. It aligns with the continuous evidence review process of the International Liaison Committee on Resuscitation, with updates published when the International Liaison Committee on Resuscitation completes a literature review based on new published evidence. This update provides the evidence review and treatment recommendations for advanced airway management in pediatric cardiac arrest, extracorporeal cardiopulmonary resuscitation in pediatric cardiac arrest, and pediatric targeted temperature management during post-cardiac arrest care. The writing group analyzed the systematic reviews and the original research published for each of these topics. For airway management, the writing group concluded that it is reasonable to continue bag-mask ventilation (versus attempting an advanced airway such as endotracheal intubation) in patients with out-of-hospital cardiac arrest. When extracorporeal membrane oxygenation protocols and teams are readily available, extracorporeal cardiopulmonary resuscitation should be considered for patients with cardiac diagnoses and in-hospital cardiac arrest. Finally, it is reasonable to use targeted temperature management of 32°C to 34°C followed by 36°C to 37.5°C, or to use targeted temperature management of 36°C to 37.5°C, for pediatric patients who remain comatose after resuscitation from out-of-hospital cardiac arrest or in-hospital cardiac arrest.

2019 American Heart Association Focused Update on Pediatric Basic Life Support: An Update to the American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.

This 2019 focused update to the American Heart Association pediatric basic life support guidelines follows the 2019 systematic review of the effects of dispatcher-assisted cardiopulmonary resuscitation (DA-CPR) on survival of infants and children with out-of-hospital cardiac arrest. This systematic review and the primary studies identified were analyzed by the Pediatric Task Force of the International Liaison Committee on Resuscitation. It aligns with the International Liaison Committee on Resuscitation's continuous evidence review process, with updates published when the International Liaison Committee on Resuscitation completes a literature review based on new published evidence. This update summarizes the available pediatric evidence supporting DA-CPR and provides treatment recommendations for DA-CPR for pediatric out-of-hospital cardiac arrest. Four new pediatric studies were reviewed. A systematic review of this data identified the association of a significant improvement in the rates of bystander CPR and in survival 1 month after cardiac arrest with DA-CPR. The writing group recommends that emergency medical dispatch centers offer DA-CPR for presumed pediatric cardiac arrest, especially when no bystander CPR is in progress. No recommendation could be made for or against DA-CPR instructions when bystander CPR is already in progress.

Pediatric Post-Cardiac Arrest Care: A Scientific Statement From the American Heart Association.

Successful resuscitation from cardiac arrest results in a post-cardiac arrest syndrome, which can evolve in the days to weeks after return of sustained circulation. The components of post-cardiac arrest syndrome are brain injury, myocardial dysfunction, systemic ischemia/reperfusion response, and persistent precipitating pathophysiology. Pediatric post-cardiac arrest care focuses on anticipating, identifying, and treating this complex physiology to improve survival and neurological outcomes. This scientific statement on post-cardiac arrest care is the result of a consensus process that included pediatric and adult emergency medicine, critical care, cardiac critical care, cardiology, neurology, and nursing specialists who analyzed the past 20 years of pediatric cardiac arrest, adult cardiac arrest, and pediatric critical illness peer-reviewed published literature. The statement summarizes the epidemiology, pathophysiology, management, and prognostication after return of sustained circulation after cardiac arrest, and it provides consensus on the current evidence supporting elements of pediatric post-cardiac arrest care.

2019 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations: Summary From the Basic Life Support; Advanced Life Support; Pediatric Life Support; Neonatal Life Support; Education, Implementation, and Teams; and First Aid Task Forces.

The International Liaison Committee on Resuscitation has initiated a continuous review of new, peer-reviewed, published cardiopulmonary resuscitation science. This is the third annual summary of the International Liaison Committee on Resuscitation International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. It addresses the most recent published resuscitation evidence reviewed by International Liaison Committee on Resuscitation Task Force science experts. This summary addresses the role of cardiac arrest centers and dispatcher-assisted cardiopulmonary resuscitation, the role of extracorporeal cardiopulmonary resuscitation in adults and children, vasopressors in adults, advanced airway interventions in adults and children, targeted temperature management in children after cardiac arrest, initial oxygen concentration during resuscitation of newborns, and interventions for presyncope by first aid providers. Members from 6 International Liaison Committee on Resuscitation task forces have assessed, discussed, and debated the certainty of the evidence on the basis of the Grading of Recommendations, Assessment, Development, and Evaluation criteria, and their statements include consensus treatment recommendations. Insights into the deliberations of the task forces are provided in the Justification and Evidence to Decision Framework Highlights sections. The task forces also listed priority knowledge gaps for further research.

2018 American Heart Association Focused Update on Pediatric Advanced Life Support: An Update to the American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.

This 2018 American Heart Association focused update on pediatric advanced life support guidelines for cardiopulmonary resuscitation and emergency cardiovascular care follows the 2018 evidence review performed by the Pediatric Task Force of the International Liaison Committee on Resuscitation. It aligns with the International Liaison Committee on Resuscitation's continuous evidence review process, and updates are published when the group completes a literature review based on new published evidence. This update provides the evidence review and treatment recommendation for antiarrhythmic drug therapy in pediatric shock-refractory ventricular fibrillation/pulseless ventricular tachycardia cardiac arrest. As was the case in the pediatric advanced life support section of the "2015 American Heart Association Guidelines Update for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care," only 1 pediatric study was identified. This study reported a statistically significant improvement in return of spontaneous circulation when lidocaine administration was compared with amiodarone for pediatric ventricular fibrillation/pulseless ventricular tachycardia cardiac arrest. However, no difference in survival to hospital discharge was observed among patients who received amiodarone, lidocaine, or no antiarrhythmic medication. The writing group reaffirmed the 2015 pediatric advanced life support guideline recommendation that either lidocaine or amiodarone may be used to treat pediatric patients with shock-refractory ventricular fibrillation or pulseless ventricular tachycardia.

2017 American Heart Association Focused Update on Pediatric Basic Life Support and Cardiopulmonary Resuscitation Quality: An Update to the American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.

This focused update to the American Heart Association guidelines for cardiopulmonary resuscitation (CPR) and emergency cardiovascular care follows the Pediatric Task Force of the International Liaison Committee on Resuscitation evidence review. It aligns with the International Liaison Committee on Resuscitation's continuous evidence review process, and updates are published when the International Liaison Committee on Resuscitation completes a literature review based on new science. This update provides the evidence review and treatment recommendation for chest compression-only CPR versus CPR using chest compressions with rescue breaths for children <18 years of age. Four large database studies were available for review, including 2 published after the "2015 American Heart Association Guidelines Update for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care." Two demonstrated worse 30-day outcomes with chest compression-only CPR for children 1 through 18 years of age, whereas 2 studies documented no difference between chest compression-only CPR and CPR using chest compressions with rescue breaths. When the results were analyzed for infants <1 year of age, CPR using chest compressions with rescue breaths was better than no CPR but was no different from chest compression-only CPR in 1 study, whereas another study observed no differences among chest compression-only CPR, CPR using chest compressions with rescue breaths, and no CPR. CPR using chest compressions with rescue breaths should be provided for infants and children in cardiac arrest. If bystanders are unwilling or unable to deliver rescue breaths, we recommend that rescuers provide chest compressions for infants and children.

Cardiopulmonary Resuscitation in Infants and Children With Cardiac Disease: A Scientific Statement From the American Heart Association.

Cardiac arrest occurs at a higher rate in children with heart disease than in healthy children. Pediatric basic life support and advanced life support guidelines focus on delivering high-quality resuscitation in children with normal hearts. The complexity and variability in pediatric heart disease pose unique challenges during resuscitation. A writing group appointed by the American Heart Association reviewed the literature addressing resuscitation in children with heart disease. MEDLINE and Google Scholar databases were searched from 1966 to 2015, cross-referencing pediatric heart disease with pertinent resuscitation search terms. The American College of Cardiology/American Heart Association classification of recommendations and levels of evidence for practice guidelines were used. The recommendations in this statement concur with the critical components of the 2015 American Heart Association pediatric basic life support and pediatric advanced life support guidelines and are meant to serve as a resuscitation supplement. This statement is meant for caregivers of children with heart disease in the prehospital and in-hospital settings. Understanding the anatomy and physiology of the high-risk pediatric cardiac population will promote early recognition and treatment of decompensation to prevent cardiac arrest, increase survival from cardiac arrest by providing high-quality resuscitations, and improve outcomes with postresuscitation care.

2018 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations Summary.

The International Liaison Committee on Resuscitation has initiated a continuous review of new, peer-reviewed, published cardiopulmonary resuscitation science. This is the second annual summary of International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations that includes the most recent cardiopulmonary resuscitation science reviewed by the International Liaison Committee on Resuscitation. This summary addresses the role of antiarrhythmic drugs in adults and children and includes the Advanced Life Support Task Force and Pediatric Task Force consensus statements, which summarize the most recent published evidence and an assessment of the quality of the evidence based on Grading of Recommendations, Assessment, Development, and Evaluation criteria. The statements include consensus treatment recommendations approved by members of the relevant task forces. Insights into the deliberations of each task force are provided in the Values and Preferences and Task Force Insights sections. Finally, the task force members have listed the top knowledge gaps for further research.

2017 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations Summary.

The International Liaison Committee on Resuscitation has initiated a near-continuous review of cardiopulmonary resuscitation science that replaces the previous 5-year cyclic batch-and-queue approach process. This is the first of an annual series of International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations summary articles that will include the cardiopulmonary resuscitation science reviewed by the International Liaison Committee on Resuscitation in the previous year. The review this year includes 5 basic life support and 1 pediatric Consensuses on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. Each of these includes a summary of the science and its quality based on Grading of Recommendations, Assessment, Development, and Evaluation criteria and treatment recommendations. Insights into the deliberations of the International Liaison Committee on Resuscitation task force members are provided in Values and Preferences sections. Finally, the task force members have prioritized and listed the top 3 knowledge gaps for each population, intervention, comparator, and outcome question.

Characterization of Pediatric In-Hospital Cardiopulmonary Resuscitation Quality Metrics Across an International Resuscitation Collaborative.

OBJECTIVES: Pediatric in-hospital cardiac arrest cardiopulmonary resuscitation quality metrics have been reported in few children less than 8 years. Our objective was to characterize chest compression fraction, rate, depth, and compliance with 2015 American Heart Association guidelines across multiple pediatric hospitals. DESIGN: Retrospective observational study of data from a multicenter resuscitation quality collaborative from October 2015 to April 2017. SETTING: Twelve pediatric hospitals across United States, Canada, and Europe. PATIENTS: In-hospital cardiac arrest patients (age < 18 yr) with quantitative cardiopulmonary resuscitation data recordings. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: There were 112 events yielding 2,046 evaluable 60-second epochs of cardiopulmonary resuscitation (196,669 chest compression). Event cardiopulmonary resuscitation metric summaries (median [interquartile range]) by age: less than 1 year (38/112): chest compression fraction 0.88 (0.61-0.98), chest compression rate 119/min (110-129), and chest compression depth 2.3 cm (1.9-3.0 cm); for 1 to less than 8 years (42/112): chest compression fraction 0.94 (0.79-1.00), chest compression rate 117/min (110-124), and chest compression depth 3.8 cm (2.9-4.6 cm); for 8 to less than 18 years (32/112): chest compression fraction 0.94 (0.85-1.00), chest compression rate 117/min (110-123), chest compression depth 5.5 cm (4.0-6.5 cm). "Compliance" with guideline targets for 60-second chest compression "epochs" was predefined: chest compression fraction greater than 0.80, chest compression rate 100-120/min, and chest compression depth: greater than or equal to 3.4 cm in less than 1 year, greater than or equal to 4.4 cm in 1 to less than 8 years, and 4.5 to less than 6.6 cm in 8 to less than 18 years. Proportion of less than 1 year, 1 to less than 8 years, and 8 to less than 18 years events with greater than or equal to 60% of 60-second epochs meeting compliance (respectively): chest compression fraction was 53%, 81%, and 78%; chest compression rate was 32%, 50%, and 63%; chest compression depth was 13%, 19%, and 44%. For all events combined, total compliance (meeting all three guideline targets) was 10% (11/112). CONCLUSIONS: Across an international pediatric resuscitation collaborative, we characterized the landscape of pediatric in-hospital cardiac arrest chest compression quality metrics and found that they often do not meet 2015 American Heart Association guidelines. Guideline compliance for rate and depth in children less than 18 years is poor, with the greatest difficulty in achieving chest compression depth targets in younger children.

Sudden Cardiac Death in the Young.

Although the occurrence of sudden cardiac death (SCD) in a young person is a rare event, it is traumatic and often widely publicized. In recent years, SCD in this population has been increasingly seen as a public health and safety issue. This review presents current knowledge relevant to the epidemiology of SCD and to strategies for prevention, resuscitation, and identification of those at greatest risk. Areas of active research and controversy include the development of best practices in screening, risk stratification approaches and postmortem evaluation, and identification of modifiable barriers to providing better outcomes after resuscitation of young SCD patients. Institution of a national registry of SCD in the young will provide data that will help to answer these questions.

Implementing Cardiopulmonary Resuscitation Training Programs in High Schools: Iowa's Experience.

OBJECTIVE: To understand perceived barriers to providing cardiopulmonary resuscitation (CPR) education, implementation processes, and practices in high schools. STUDY DESIGN: Iowa has required CPR as a graduation requirement since 2011 as an unfunded mandate. A cross-sectional study was performed through multiple choice surveys sent to Iowa high schools to collect data about school demographics, details of CPR programs, cost, logistics, and barriers to implementation, as well as automated external defibrillator training and availability. RESULTS: Eighty-four schools responded (26%), with the most frequently reported school size of 100-500 students and faculty size of 25-50. When the law took effect, 51% of schools had training programs already in place; at the time of the study, 96% had successfully implemented CPR training. Perceived barriers to implementation were staffing, time commitment, equipment availability, and cost. The average estimated startup cost was <$1000 US, and the yearly maintenance cost was <$500 with funds typically allocated from existing school resources. The facilitator was a school official or volunteer for 81% of schools. Average estimated training time commitment per student was <2 hours. Automated external defibrillators are available in 98% of schools, and 61% include automated external defibrillator training in their curriculum. CONCLUSIONS: Despite perceived barriers, school CPR training programs can be implemented with reasonable resource and time allocations.

Amiodarone Versus Lidocaine for Pediatric Cardiac Arrest Due to Ventricular Arrhythmias: A Systematic Review.

OBJECTIVE: We performed a systematic review as part of the International Liaison Committee on Resuscitation process to create a consensus on science statement regarding amiodarone or lidocaine during pediatric cardiac arrest for the 2015 International Liaison Committee on Resuscitation's Consensus on Science and Treatment Recommendations. DATA SOURCES: Studies were identified from comprehensive searches in PubMed, Embase, and the Cochrane Library. STUDY SELECTION: Studies eligible for inclusion were randomized controlled and observational studies on the relative clinical effect of amiodarone or lidocaine in cardiac arrest. DATA EXTRACTION: Studies addressing the clinical effect of amiodarone versus lidocaine were extracted and reviewed for inclusion and exclusion criteria by the reviewers. Studies were rigorously analyzed thereafter. DATA SYNTHESIS: We identified three articles addressing lidocaine versus amiodarone in cardiac arrest: 1) a prospective study assessing lidocaine versus amiodarone for refractory ventricular fibrillation in out-of-hospital adults; 2) an observational retrospective cohort study of inpatient pediatric patients with ventricular fibrillation or pulseless ventricular tachycardia who received lidocaine, amiodarone, neither or both; and 3) a prospective study of ventricular tachycardia with a pulse in adults. The first study showed a statistically significant improvement in survival to hospital admission with amiodarone (22.8% vs 12.0%; p = 0.009) and a lack of statistical difference for survival at discharge (p = 0.34). The second article demonstrated 44% return of spontaneous circulation for amiodarone and 64% for lidocaine (odds ratio, 2.02; 1.36-3.03) with no statistical difference for survival at hospital discharge. The third article demonstrated 48.3% arrhythmia termination for amiodarone versus 10.3% for lidocaine (p < 0.05). All were classified as lower quality studies without preference for one agent. CONCLUSIONS: The confidence in effect estimates is so low that International Liaison Committee on Resuscitation felt that a recommendation to use of amiodarone over lidocaine is too speculative; we suggest that amiodarone or lidocaine can be used in the setting of pulseless ventricular tachycardia/ventricular fibrillation in infants and children.

Ventricular tachyarrhythmias after cardiac arrest in public versus at home.

BACKGROUND: The incidence of ventricular fibrillation or pulseless ventricular tachycardia as the first recorded rhythm after out-of-hospital cardiac arrest has unexpectedly declined. The success of bystander-deployed automated external defibrillators (AEDs) in public settings suggests that this may be the more common initial rhythm when out-of-hospital cardiac arrest occurs in public. We conducted a study to determine whether the location of the arrest, the type of arrhythmia, and the probability of survival are associated. METHODS: Between 2005 and 2007, we conducted a prospective cohort study of out-of-hospital cardiac arrest in adults in 10 North American communities. We assessed the frequencies of ventricular fibrillation or pulseless ventricular tachycardia and of survival to hospital discharge for arrests at home as compared with arrests in public. RESULTS: Of 12,930 evaluated out-of-hospital cardiac arrests, 2042 occurred in public and 9564 at home. For cardiac arrests at home, the incidence of ventricular fibrillation or pulseless ventricular tachycardia was 25% when the arrest was witnessed by emergency-medical-services (EMS) personnel, 35% when it was witnessed by a bystander, and 36% when a bystander applied an AED. For cardiac arrests in public, the corresponding rates were 38%, 60%, and 79%. The adjusted odds ratio for initial ventricular fibrillation or pulseless ventricular tachycardia in public versus at home was 2.28 (95% confidence interval [CI], 1.96 to 2.66; P < 0.001) for bystander-witnessed arrests and 4.48 (95% CI, 2.23 to 8.97; P<0.001) for arrests in which bystanders applied AEDs. The rate of survival to hospital discharge was 34% for arrests in public settings with AEDs applied by bystanders versus 12% for arrests at home (adjusted odds ratio, 2.49; 95% CI, 1.03 to 5.99; P = 0.04). CONCLUSIONS: Regardless of whether out-of-hospital cardiac arrests are witnessed by EMS personnel or bystanders and whether AEDs are applied by bystanders, the proportion of arrests with initial ventricular fibrillation or pulseless ventricular tachycardia is much greater in public settings than at home. The incremental value of resuscitation strategies, such as the ready availability of an AED, may be related to the place where the arrest occurs.