Make it two: A case report of dual sequential external defibrillation

Colin R. Bell; Adam Szulewski; Steven C. Brooks

doi:10.1017/cem.2017.42

Abstract 12769: Amplitude-Spectral Area of the Ventricular Fibrillation Waveform and Chest Compression Quality in Witnessed and Unwitnessed Out-Of-Hospital Cardiac Arrest: Can We Predict Who is Unlikely to Survive?

Circulation ◽

10.1161/circ.130.suppl_2.12769 ◽

2014 ◽

Vol 130 (suppl_2) ◽

Author(s):

Julia Indik ◽

Zacherie Conover ◽

Meghan McGovern ◽

Annemarie Silver ◽

Daniel Spaite ◽

...

Keyword(s):

Logistic Regression ◽

Cardiac Arrest ◽

Ventricular Fibrillation ◽

Hospital Discharge ◽

Chest Compression ◽

Stepwise Logistic Regression ◽

Individual Subject ◽

Spectral Area ◽

Initial Rhythm ◽

Hospital Cardiac Arrest

Background: Previous investigations in human out of hospital cardiac arrest (OHCA) due to ventricular fibrillation (VF) have shown that the frequency-based waveform characteristic, amplitude spectral area (AMSA) predicts defibrillation success and is associated with survival to hospital discharge. We evaluated the relative strength of factors associated with hospital discharge including witnessed/unwitnessed status, chest compression (CC) quality and AMSA. We then investigated if there is a threshold value for AMSA that can identify patients who are unlikely to survive. Methods: Adult OHCA patients (age ≥18), with initial rhythm of VF from an Utstein-Style database (collected from 2 EMS systems) were analyzed. AMSA was measured from the waveform immediately prior to each shock, and averaged for each individual subject (AMSA-ave). Univariate and stepwise multivariable logistic regression, and receiver-operator-characteristic (ROC) analyses were performed. Factors analyzed: age, sex, witnessed status, time from dispatch to monitor/defibrillator application, number of shocks, mean CC rate, depth, and release velocity (RV). Results: 140 subjects were analyzed, [104 M (74%), age 62 ± 14 yrs, witnessed 65%]. Survival was 38% in witnessed and 16% in unwitnessed arrest. In univariate analyses, age (P=0.001), witnessed status (P=0.009), AMSA-ave (P<0.001), mean CC depth (P=0.025), and RV (P< 0.001) were associated with survival. Stepwise logistic regression identified AMSA-ave (P<0.001), RV (P=0.001) and age (P=0.018) as independently associated with survival. The area under the curve (ROC analysis) was 0.849. The probability of survival was < 5% in witnessed arrest for AMSA-ave < 5 mV-Hz, and in unwitnessed arrest for AMSA-ave < 15 mV-Hz. Conclusion: In OHCA with an initial rhythm of VF, AMSA-ave and CC RV are highly associated with survival. Further study is needed to evaluate whether AMSA-ave may be useful to identify patients highly unlikely to survive.

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Abstract 17847: Gasping is a Valid Predictor Of ROSC and Hospital Discharge for In-hospital Cardiac Arrest Occurring on the Ward

Circulation ◽

10.1161/circ.132.suppl_3.17847 ◽

2015 ◽

Vol 132 (suppl_3) ◽

Author(s):

Luca Marengo ◽

Wolfgang Ummenhofer ◽

Gerster Pascal ◽

Falko Harm ◽

Marc Lüthy ◽

...

Keyword(s):

Cardiac Arrest ◽

Ventricular Fibrillation ◽

Hospital Discharge ◽

Survival Data ◽

Neurological Outcome ◽

Rapid Response Team ◽

Spontaneous Circulation ◽

University Hospital ◽

Data Set ◽

Hospital Cardiac Arrest

Introduction: Agonal respiration has been shown to be commonly associated with witnessed events, ventricular fibrillation, and increased survival during out-of-hospital cardiac arrest. There is little information on incidence of gasping for in-hospital cardiac arrest (IHCA). Our “Rapid Response Team” (RRT) missions were monitored between December 2010 and March 2015, and the prevalence of gasping and survival data for IHCA were investigated. Methods: A standardized extended in-hospital Utstein data set of all RRT-interventions occurring at the University Hospital Basel, Switzerland, from December 13, 2010 until March 31, 2015 was consecutively collected and recorded in Microsoft Excel (Microsoft Corp., USA). Data were analyzed using IBM SPSS Statistics 22.0 (IBM Corp., USA), and are presented as descriptive statistics. Results: The RRT was activated for 636 patients, with 459 having a life-threatening status (72%; 33 missing). 270 patients (59%) suffered IHCA. Ventricular fibrillation or pulseless ventricular tachycardia occurred in 42 patients (16% of CA) and were associated with improved return of spontaneous circulation (ROSC) (36 (97%) vs. 143 (67%; p<0.001)), hospital discharge (25 (68%) vs. 48 (23%; p<0.001)), and discharge with good neurological outcome (Cerebral Performance Categories of 1 or 2 (CPC) (21 (55%) vs. 41 (19%; p<0.001)). Gasping was seen in 128 patients (57% of CA; 46 missing) and was associated with an overall improved ROSC (99 (78%) vs. 55 (59%; p=0.003)). In CAs occurring on the ward (154, 57% of all CAs), gasping was associated with a higher proportion of shockable rhythms (11 (16%) vs. 2 (3%; p=0.019)), improved ROSC (62 (90%) vs. 34 (55%; p<0.001)), and hospital discharge (21 (32%) vs. 7 (11%; p=0.006)). Gasping was not associated with neurological outcome. Conclusions: Gasping was frequently observed accompanying IHCA. The faster in-hospital patient access is probably the reason for the higher prevalence compared to the prehospital setting. For CA on the ward without continuous monitoring, gasping correlates with increased shockable rhythms, ROSC, and hospital discharge.

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Dispatcher Identification of Out-of-Hospital Cardiac Arrest and Neurologically Intact Survival: A Retrospective Cohort Study

Prehospital and Disaster Medicine ◽

10.1017/s1049023x19005077 ◽

2019 ◽

Vol 35 (1) ◽

pp. 17-23

Author(s):

Julian G. Mapp ◽

Anthony M. Darrington ◽

Stephen A. Harper ◽

Chetan U. Kharod ◽

David A. Miramontes ◽

...

Keyword(s):

Cardiac Arrest ◽

Cohort Study ◽

Hospital Discharge ◽

Retrospective Cohort Study ◽

Retrospective Cohort ◽

San Antonio ◽

Cerebral Performance Category ◽

Published Data ◽

Neurologically Intact ◽

Hospital Cardiac Arrest

AbstractIntroduction:To date, there are no published data on the association of patient-centered outcomes and accurate public-safety answering point (PSAP) dispatch in an American population. The goal of this study is to determine if PSAP dispatcher recognition of out-of-hospital cardiac arrest (OHCA) is associated with neurologically intact survival to hospital discharge.Methods:This retrospective cohort study is an analysis of prospectively collected Quality Assurance/Quality Improvement (QA/QI) data from the San Antonio Fire Department (SAFD; San Antonio, Texas USA) OHCA registry from January 2013 through December 2015. Exclusion criteria were: Emergency Medical Services (EMS)-witnessed arrest, traumatic arrest, age <18 years old, no dispatch type recorded, and missing outcome data. The primary exposure was dispatcher recognition of cardiac arrest. The primary outcome was neurologically intact survival (defined as Cerebral Performance Category [CPC] 1 or 2) to hospital discharge. The secondary outcomes were: bystander cardiopulmonary resuscitation (CPR), automated external defibrillator (AED) use, and prehospital return of spontaneous return of circulation (ROSC).Results:Of 3,469 consecutive OHCA cases, 2,569 cases were included in this analysis. The PSAP dispatched 1,964/2,569 (76.4%) of confirmed OHCA cases correctly. The PSAP dispatched 605/2,569 (23.6%) of confirmed OHCA cases as another chief complaint. Neurologically intact survival to hospital discharge occurred in 99/1,964 (5.0%) of the recognized cardiac arrest group and 28/605 (4.6%) of the unrecognized cardiac arrest group (OR = 1.09; 95% CI, 0.71–1.70). Bystander CPR occurred in 975/1,964 (49.6%) of the recognized cardiac arrest group versus 138/605 (22.8%) of the unrecognized cardiac arrest group (OR = 3.34; 95% CI, 2.70–4.11).Conclusion:This study found no association between PSAP dispatcher identification of OHCA and neurologically intact survival to hospital discharge. Dispatcher identification of OHCA remains an important, but not singularly decisive link in the OHCA chain of survival.

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Predictors of Survival from Perioperative Cardiopulmonary Arrests

Anesthesiology ◽

10.1097/aln.0b013e318289bafe ◽

2013 ◽

Vol 119 (6) ◽

pp. 1322-1339 ◽

Cited By ~ 38

Author(s):

Satya Krishna Ramachandran ◽

Jill Mhyre ◽

Sachin Kheterpal ◽

Robert E. Christensen ◽

Kristen Tallman ◽

...

Keyword(s):

Cardiac Arrest ◽

Ventricular Tachycardia ◽

Ventricular Fibrillation ◽

Operating Room ◽

Hospital Discharge ◽

Ventilatory Support ◽

Neurological Status ◽

Secondary Outcome ◽

Postanesthesia Care Unit ◽

Neurologically Intact

Abstract Background: Perioperative cardiopulmonary arrests are uncommon and little is known about rates and predictors of in-hospital survival. Methods: Using the Get With The Guidelines®-Resuscitation national in-hospital resuscitation registry, we identified all patients aged 18 yr or older who experienced an index, pulseless cardiac arrest in the operating room or within 24 h postoperatively. The primary outcome was survival to hospital discharge, and the secondary outcome was neurologically intact recovery among survivors. Multivariable logistic regression models using generalized estimating equation models were used to identify independent predictors of survival and neurologically intact survival. Results: A total of 2,524 perioperative cardiopulmonary arrests were identified from 234 hospitals. The overall rate of survival to discharge was 31.7% (799/2,524), including 41.8% (254/608) for ventricular tachycardia and ventricular fibrillation, 30.5% (296/972) for asystole, and 26.4% (249/944) for pulseless electrical activity. Ventricular fibrillation and pulseless ventricular tachycardia were independently associated with improved survival. Asystolic arrests occurring in the operating room and postanesthesia care unit were associated with improved survival when compared to other perioperative locations. Among patients with neurological status assessment at discharge, the rate of neurologically intact survival was 64.0% (473/739). Prearrest neurological status at admission, patient age, inadequate natural airway, prearrest ventilatory support, duration of event, and event location were significant predictors of neurological status at discharge. Conclusion: Among patients with a perioperative cardiac arrest, one in three survived to hospital discharge, and good neurological outcome was noted in two of three survivors.

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Prognostic value of changes in the cardiac arrest rhythms from the prehospital stage to the emergency department in out-of-hospital cardiac arrest patients without prehospital returns of spontaneous circulation: A nationwide observational study

PLoS ONE ◽

10.1371/journal.pone.0257883 ◽

2021 ◽

Vol 16 (9) ◽

pp. e0257883

Author(s):

Jae Guk Kim ◽

Hyungoo Shin ◽

Jun Hwi Cho ◽

Hyun Young Choi ◽

Wonhee Kim ◽

...

Keyword(s):

Emergency Department ◽

Cardiac Arrest ◽

Propensity Score ◽

Hospital Discharge ◽

Prognostic Value ◽

Spontaneous Circulation ◽

Shock Group ◽

Electrical Shock ◽

Neurological Outcomes ◽

Hospital Cardiac Arrest

Background This study aimed to assess the prognostic value of the changes in cardiac arrest rhythms from the prehospital stage to the ED (emergency department) in out-of-hospital cardiac arrest (OHCA) patients without prehospital returns of spontaneous circulation (ROSC). Methods This retrospective analysis was performed using nationwide population-based OHCA data from South Korea between 2012 and 2016. Patients with OHCA with medical causes and without prehospital ROSC were included and divided into four groups according to the nature of their cardiac arrest rhythms (shockable or non-shockable) in the prehospital stage and in the ED: (1) the shockable and shockable (Shock-Shock) group, (2) the shockable and non-shockable (Shock-NShock) group, (3) the non-shockable and shockable (NShock-Shock) group, and (4) the non-shockable and non-shockable (NShock-NShock) group. The presence of a shockable rhythm was confirmed based on the delivery of an electrical shock. Propensity score matching and multivariate logistic regression analyses were used to assess the effect of changes in the cardiac rhythms on patient outcomes. The primary outcome was sustained ROSC in the ED; the secondary outcomes were survival to hospital discharge and good neurological outcomes at hospital discharge. Results After applying the exclusion criteria, 51,060 eligible patients were included in the study (Shock-Shock, 4223; Shock-NShock, 3060; NShock-Shock, 11,509; NShock-NShock, 32,268). The propensity score-matched data were extracted from the six comparative subgroups. For sustained ROSC in the ED, Shock-Shock showed a higher likelihood than Shock-NShock (P <0.01) and NShock-NShock (P <0.01), Shock-NShock showed a lower likelihood than NShock-Shock (P <0.01) and NShock-NShock (P <0.01), NShock-Shock showed a higher likelihood NShock-NShock (P <0.01). For survival to hospital discharge, Shock-Shock showed a higher likelihood than Shock-NShock (P <0.01), NShock-Shock (P <0.01), and NShock-NShock (P <0.01), Shock-NShock showed a higher likelihood than NShock-Shock (P <0.01) and NShock-NShock (P <0.01), of sustained ROSC in the ED. For good neurological outcomes, Shock-Shock showed higher likelihood than Shock-NShock (P <0.01), NShock-Shock (P <0.01), and NShock-NShock (P <0.01), Shock-NShock showed better likelihood than NShock-NShock (P <0.01), NShock-Shock showed a better likelihood than NShock-NShock (P <0.01). Conclusion Sustained ROSC in the ED may be expected for patients with shockable rhythms in the ED compared with those with non-shockable rhythms in the ED. For the clinical outcomes, survival to hospital discharge and neurological outcomes, patients with Shock-Shock showed the best outcome, whereas patients with NShock-NShock showed the poorest outcome and Shock-NShock showed a higher likelihood of achieving survival to hospital discharge with no significant differences in the neurological outcomes compared with NShock-Shock.

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Abstract 10617: Antiarrhythmic Use and the Posterior Probability of Neurologically Intact Survival in a Reanalysis of the Amiodarone, Lidocaine or Placebo Study in Out-of-Hospital Cardiac Arrest

Circulation ◽

10.1161/circ.144.suppl_2.10617 ◽

2021 ◽

Vol 144 (Suppl_2) ◽

Author(s):

Frederick J Brown ◽

Steven E Rigdon ◽

David L Brown

Keyword(s):

Cardiac Arrest ◽

Ventricular Fibrillation ◽

Posterior Probability ◽

Credible Interval ◽

Antiarrhythmic Therapy ◽

Absolute Difference ◽

Prior Probabilities ◽

The Absolute ◽

Neurologically Intact ◽

Hospital Cardiac Arrest

Introduction: There are no randomized controlled trials (RCT) demonstrating improvement in neurologically intact survival from antiarrhythmic therapy given during out-of-hospital cardiac arrest (OHCA) from ventricular fibrillation/tachycardia (VF/VT). The Amiodarone, Lidocaine or Placebo Study in Out-of-Hospital Cardiac Arrest (ALPS) was an RCT of amiodarone, lidocaine or placebo whose primary end-point was survival to hospital discharge. We sought to estimate the posterior probability of the absolute risk difference of neurologically intact survival (modified Rankin Score ≤ 3) from antiarrhythmic use (amiodarone or lidocaine) compared to placebo and from the use amiodarone versus lidocaine. Methods: We performed a Bayesian reanalysis on the per-protocol population of the ALPS trial in order to calculate the posterior probability of neurologically intact survival. We derived prior probabilities from the Amiodarone for Resuscitation after Out-of-Hospital Cardiac Arrest Due to Ventricular Fibrillation (ARREST) and Amiodarone Compared with Lidocaine for Shock-Resistant Ventricular Fibrillation (ALIVE) trials. We considered a clinically meaningful absolute difference to be ≥ 1%. Results: The posterior median probability of the absolute difference in neurologically intact survival between antiarrhythmic therapy and placebo was 2.2% (95% credible interval of -0.15% to 4.7%). There is a 96% chance that antiarrhythmic improves neurologic outcome and 86% chance of a clinically meaningful improvement. The posterior median probability of the absolute difference in neurologically intact survival between amiodarone and lidocaine was 1.5% (95% credible interval -1.6% to 4.5%). Conclusion: The results of this Bayesian analysis of the ALPS trial using likely optimistic prior probabilities derived from the ARREST trial may help inform clinicians of the value of antiarrhythmic therapy in OHCA.

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The impact of ventricular fibrillation amplitude on successful cardioversion, resuscitation duration, and survival after out-of-hospital cardiac arrest

Critical Care and Resuscitation ◽

10.51893/2021.2.oa7 ◽

2021 ◽

Vol 23 (2) ◽

pp. 202-210

Author(s):

Ziad Nehme ◽

◽

Steffi Burns ◽

Jocasta Ball ◽

Stephen Bernard ◽

...

Keyword(s):

Cardiac Arrest ◽

Ventricular Fibrillation ◽

Hospital Discharge ◽

Medical Service ◽

Multivariable Analysis ◽

Shock Amplitude ◽

International Data ◽

Low Amplitude ◽

The Impact ◽

Hospital Cardiac Arrest

OBJECTIVE: We sought to examine the incidence of low amplitude ventricular fibrillation and its impact on successful cardioversion, duration of resuscitation, and survival to hospital discharge in patients with out-of-hospital cardiac arrest (OHCA). DESIGN: Retrospective analysis from a statewide registry. SETTING: Victoria, Australia. PARTICIPANTS: Consecutive initial ventricular fibrillation arrests with an emergency medical service (EMS)-attempted resuscitation between 1 February 2019 and 30 January 2020. MAIN OUTCOME MEASURES: Survival to hospital discharge, successful cardioversion, and duration of resuscitation. RESULTS: Of the 471 initial ventricular fibrillation arrests, 429 (91.1%) had sufficient electrocardiogram data for review. The median initial and final ventricular fibrillation amplitude did not differ (0.3 mV; interquartile range [IQR], 0.2–0.5 mV). The final pre-shock amplitude was ≤ 0.1 mV (very fine) and ≤ 0.2 mV (fine) in 22.8% and 37.5% of cases respectively. In a multivariable analysis, only the time between emergency call and first defibrillation was associated with a low initial ventricular fibrillation amplitude ≤ 0.2 mV (adjusted odds ratio [aOR], 1.07; 95% CI, 1.02–1.13; P = 0.004). After adjustment for arrest factors, every 0.1 mV increase in final amplitude was independently associated with survival to hospital discharge (aOR, 1.26; 95% CI, 1.14–1.39; P < 0.001) and initial cardioversion success (aOR, 1.19; 95% CI, 1.07–1.32; P = 0.001). The duration of resuscitation also increased by 1.7 minutes (95% CI, 1.03–2.36; P < 0.001) for every 0.1 mV increase in final amplitude. CONCLUSION: More than one-third of initial ventricular fibrillation OHCA cases were low in amplitude. Comparative international data are needed to better understand how low amplitude ventricular fibrillation rhythms confound the measurement of OHCA interventions and international benchmarks for survival outcomes.

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Clinical case review: out-of-hospital cardiac arrest following thyroid storm

Journal of Paramedic Practice ◽

10.12968/jpar.2021.13.4.144 ◽

2021 ◽

Vol 13 (4) ◽

pp. 144-150

Author(s):

Matthew Hale ◽

Jo Mildenhall ◽

Christopher Hook ◽

James Burt

Keyword(s):

Cardiac Arrest ◽

Ventricular Fibrillation ◽

Hospital Discharge ◽

Clinical Case ◽

Spontaneous Circulation ◽

Thyroid Storm ◽

Case Review ◽

Return Of Spontaneous Circulation ◽

Good Outcome ◽

Hospital Cardiac Arrest

Acute thyrotoxicosis (thyroid storm) caused by hyperthyroidism is a rare but severe endocrine imbalance which, in extreme cases, may lead to ventricular fibrillation and ultimately, without intervention, death. The authors attended such an incident and, following clinical interventions, achieved return of spontaneous circulation with a good outcome for the patient and subsequent hospital discharge.

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Abstract 336: Data-driven Classification of Arrest Location for Emergency Department Cardiac Arrests

Circulation ◽

10.1161/circ.142.suppl_4.336 ◽

2020 ◽

Vol 142 (Suppl_4) ◽

Author(s):

Nancy Mikati ◽

Clifton W Callaway ◽

Patrick J Coppler ◽

Jonathan Elmer

Keyword(s):

Emergency Department ◽

Cardiac Arrest ◽

Unsupervised Learning ◽

Hospital Discharge ◽

Medical Center ◽

Academic Medical Center ◽

Clinical Information ◽

Large Majority ◽

Cluster Center ◽

Hospital Cardiac Arrest

Introduction: Out-of-hospital cardiac arrest (OHCA), in-hospital cardiac arrest (IHCA), and emergency department (ED) cardiac arrests differ in epidemiology, etiology, and outcomes. Resuscitation research is inconsistent in how ED arrests are classified. We used unsupervised learning to compare ED arrests to non-ED OHCA and to non-ED IHCA. Hypothesis: Clinical features of ED cardiac arrest patients who achieve return of spontaneous circulation (ROSC) are more similar to IHCA than to OHCA. Methods: We performed a retrospective study including all patients resuscitated from cardiac arrest who were treated at a single academic medical center from January 2010 to December 2019. We abstracted clinical information from our prospective registry, including the details of arrest location (ED arrests, OHCA, or IHCA); age; sex; initial arrest rhythm; number of doses of epinephrine, bicarbonate and shocks given during the arrest; duration of arrest; most advanced airway placed intra-arrest; number of rearrests; early post-arrest illness severity (Pittsburgh Cardiac Arrest Category: PCAC); and survival to hospital discharge. We used unsupervised learning (K-prototypes) to identify clusters within the OHCA and IHCA cohorts. We determined the number of subgroups using Scree plots. Finally, we assigned individual ED arrest patients the nearest OHCA or IHCA cluster based on the shortest Gower distance from that patient to the nearest cluster center. Results: We included 2,723 patients: 1,709 (63%) OHCA, 642 (23%) IHCA, and 372 (14%) ED arrests. We identified 3 clusters in the OHCA cohort, and 4 clusters in the IHCA cohort. Of the total ED arrest cases, 292 (78%) most closely resembled an IHCA cluster and 80 (22%) most closely resembled an OHCA cluster. The large majority (64%) of ED arrests that were closest to an IHCA cluster survived to hospital discharge; 50% of this subset were awake post-arrest (PCAC I), and 16% were deeply comatose (PCAC IV). In contrast, only 13% of ED arrests that were closest to an OHCA cluster survived to hospital discharge; 65% of this subset were deeply comatose (PCAC IV) and only 5% were awake post arrest (PCAC I). Conclusion: Among cardiac arrest patients with ROSC, the large majority of ED arrests resemble IHCA more than OHCA.

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DOuble SEquential External Defibrillation for Refractory Ventricular Fibrillation (DOSE VF): study protocol for a randomized controlled trial

Trials ◽

10.1186/s13063-020-04904-z ◽

2020 ◽

Vol 21 (1) ◽

Author(s):

Ian R. Drennan ◽

Paul Dorian ◽

Shelley McLeod ◽

Ruxandra Pinto ◽

Damon C. Scales ◽

...

Keyword(s):

Randomized Controlled Trial ◽

Cardiac Arrest ◽

Ventricular Tachycardia ◽

Ventricular Fibrillation ◽

Hospital Discharge ◽

Controlled Trial ◽

Research Question ◽

Cluster Randomized Trial ◽

Randomized Controlled ◽

Hospital Cardiac Arrest

Abstract Background Despite high-quality cardiopulmonary resuscitation (CPR), early defibrillation, and antiarrhythmic medications, some patients remain in refractory ventricular fibrillation (VF) during out-of-hospital cardiac arrest. These patients have worse outcomes compared to patients who respond to initial treatment. Double sequential external defibrillation (DSED) and vector change (VC) defibrillation have been proposed as viable options for patients in refractory VF. However, the evidence supporting the use of novel defibrillation strategies is inconclusive. The objective of this study is to compare two novel therapeutic defibrillation strategies (DSED and VC) against standard defibrillation for patients with treatment refractory VF or pulseless ventricular tachycardia (pVT) during out-of-hospital cardiac arrest. Research question Among adult (≥ 18 years) patients presenting in refractory VF or pulseless ventricular tachycardia (pVT) during out-of-hospital cardiac arrest, does DSED or VC defibrillation result in greater rates of survival to hospital discharge compared to standard defibrillation? Methods This will be a three-arm, cluster randomized trial with repeated crossover conducted in six regions of Ontario, Canada (Peel, Halton, Toronto, Simcoe, London, and Ottawa), over 3 years. All adult (≥ 18 years) patients presenting in refractory VF (defined as patients presenting in VF/pVT and remaining in VF/pVT after three consecutive standard defibrillation attempts during out-of-hospital cardiac arrest of presumed cardiac etiology will be treated by one of three strategies: (1) continued resuscitation using standard defibrillation, (2) resuscitation involving DSED, or (3) resuscitation involving VC (change of defibrillation pads from anterior-lateral to anterior-posterior pad position) defibrillation. The primary outcome will be survival to hospital discharge. Secondary outcomes will include return of spontaneous circulation (ROSC), VF termination after the first interventional shock, VF termination inclusive of all interventional shocks, and number of defibrillation attempts to obtain ROSC. We will also perform an a priori subgroup analysis comparing rates of survival for those who receive “early DSED,” or first DSED shock is shock 4–6, to those who receive “late DSED,” or first DSED shock is shock 7 or later. Discussion A well-designed randomized controlled trial employing a standardized approach to alternative defibrillation strategies early in the treatment of refractory VF is urgently required to determine if the treatments of DSED or VC defibrillation impact clinical outcomes. Trial registration ClinicalTrials.gov NCT04080986. Registered on 6 September 2019.

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