Erratum to "Wolf Creek XVII Part 5: Mobile AEDs" [Resusc. Plus 16 (2023) 100500].

[This corrects the article DOI: 10.1016/j.resplu.2023.100500.].

Safety and Adverse Events During Primary Care Paramedic Interfacility Transfer of Stable STEMI Patients.

OBJECTIVE: Current guidelines recommend that patients presenting with ST-elevation myocardial infarction (STEMI) to hospitals not capable of performing primary percutaneous coronary intervention (PCI) be transferred to a PCI-capable hospital if reperfusion can be accomplished within 120 min. Most STEMI patients are accompanied by an advanced care paramedic (ACP, equivalent to EMT-P), nurse, or physician who can manage complications should they arise. In our region, stable STEMI patients are transported by primary care paramedics (PCPs, similar scope of practice to advanced EMT) in cases where a nurse, physician, or ACP paramedic is not available. Our goal was to describe adverse events and need for advanced interventions among initially stable STEMI patients during interfacility transfer by PCPs. METHODS: We reviewed ambulance and hospital records of initially stable STEMI patients (as determined by first set of vital signs documented by paramedics) transferred to a PCI-capable hospital by PCPs between March 1, 2014, and December 31, 2019. We identified whether pre-determined adverse clinical events occurred during the transport as well as the potential need for advanced care interventions not within the PCP scope of practice. Adverse events upon arrival in the PCI lab were also identified. RESULTS: Of 346 STEMI patients transferred, 179 met inclusion criteria. The mean age of included patients was 61 years (SD 12.1) and 74.9% (134/179) were male. Median transport interval was 36 min (IQR 3.0). During transport, 47/179 (26.0%) patients experienced pre-defined adverse events; for 16/47 (34%), one or more adverse events was major. Three patients met criteria for ACP interventions. One patient suffered a cardiac arrest and was promptly resuscitated with defibrillation by the PCPs. CONCLUSIONS: We found PCP-interfacility transport of initially stable STEMI patients was safe and associated with a moderate proportion of adverse events, the majority of which did not require an advanced care intervention. These findings may help decision-making to avoid delays transferring stable patients to PCI-capable centers.

Randomized controlled trials in resuscitation.

Randomized controlled trials (RCTs) are a gold standard in research and crucial to our understanding of resuscitation science. Many trials in resuscitation have had neutral findings, questioning which treatments are effective in cardiac resuscitation. While it is possible than many interventions do not improve patient outcomes, it is also possible that the large proportion of neutral findings are partially due to design limitations. RCTs can be challenging to implement, and require extensive resources, time, and funding. In addition, conducting RCTs in the out-of-hospital setting provides unique challenges that must be considered for a successful trial. This article will outline many important aspects of conducting trials in resuscitation in the out-of-hospital setting including patient and outcome selection, trial design, and statistical analysis.

Association of coronary angiography with ST-elevation and no ST-elevation in patients with refractory ventricular fibrillation - A substudy of the DOuble SEquential External Defibrillation for Refractory Ventricular Fibrillation (DOSE-VF randomized control trial).

BACKGROUND: Refractory ventricular fibrillation or pulseless ventricular tachycardia (rVF/pVT) during out-of-hospital cardiac arrest (OHCA) is associated with poor survival. Double sequential defibrillation (DSED) and vector change (VC) improved survival for rVF/pVT in the DOSE-VF RCT. However, the role of angiography and percutaneous coronary intervention (angiography/PCI) during the trial is unknown. OBJECTIVES: To determine the incidence of ST-elevation (STE) and no ST-elevation (NO-STE) on post-arrest ECG and the use of angiography/PCI in patients with rVF/pVT during the DOSE-VF RCT. METHOD: Adults (≥18-years) with rVF/pVT OHCA randomized in the DOSE-VF RCT who survived to hospital admission were included. The primary analysis compared the proportion of angiography in STE and NO-STE. We performed regression modelling to examine association between STE, the interaction with defibrillation strategy, and survival to discharge controlling for known covariates. RESULTS: We included 151 patients, 74 (49%) with STE and 77 (51%) with NO-STE. The proportion of angiography was higher in the STE cohort than NO-STE (87.8% vs 44.2%, p < 0.001); similarly the proportion of PCI was also higher (75.7% vs 9.1%, p < 0.001). Survival to discharge was similar between STE and NO-STE (63.5% vs 51.9%, p = 0.15). Use of angiography/PCI did not differ between defibrillation strategies. Decreased age (OR 0.95, 95% CI 0.92-0.98; p = 0.001) and angiography (OR 9.33, 95% CI 3.60-26.94; p < 0.001) were predictors of survival; however, STE was not. CONCLUSION: We found high rates of angiography/PCI in patients with STE compared to NO-STE, however similar rates of survival. Angiography was an independent predictor of survival. Improved rates of survival employing DSED and VC were independent of angiography/PCI.

The impact of alternate defibrillation strategies on shock-refractory and recurrent ventricular fibrillation: A secondary analysis of the DOSE VF cluster randomized controlled trial.

BACKGROUND: The DOSE VF randomized controlled trial (RCT) employed a pragmatic definition of refractory ventricular fibrillation (VF after three successive shocks). However, it remains unclear whether the underlying rhythm during the first three shocks was shock-refractory or recurrent VF. OBJECTIVE: To explore the relationship between alternate defibrillation strategies employed during the DOSE VF RCT and the type of VF, either shock-refractory VF or recurrent VF, on patient outcomes. METHODS: We performed a secondary analysis of the DOSE VF RCT. We categorized cases as shock-refractory or recurrent VF based on pre-randomization shocks (shocks 1-3). We then analyzed all subsequent (post-randomization) shocks to assess the impact of standard, vector change (VC) or double sequential external defibrillation (DSED) shocks on clinical outcomes employing logistic regression adjusted for Utstein variables, antiarrhythmics, and epinephrine. RESULTS: We included 345 patients; 60 (17%) shock-refractory VF, and 285 (83%) recurrent VF. Patients in recurrent VF had greater survival than shock-refractory VF (OR: 2.76 95% CI [1.04, 7.27]). DSED was superior to standard defibrillation for survival overall, and for patients with shock-refractory VF (28.6% vs 0%, p = 0.041) but not for those in recurrent VF. DSED was superior to standard defibrillation for return of spontaneous circulation (ROSC) and neurologic survival for shock-refractory and recurrent VF. VC defibrillation was not superior for survival or ROSC overall, for shock-refractory, or recurrent VF groups, but was superior for VF termination across all groups. CONCLUSION: DSED appears to be the superior defibrillation strategy in the DOSE VF trial, irrespective of whether the preceding VF is shock-refractory or recurrent.

Challenges & barriers for real-time integration of drones in emergency cardiac care: Lessons from the United States, Sweden, & Canada.

Importance: Out-of-hospital cardiac arrest (OHCA) is a leading cause of morbidity and mortality in the US and Europe (∼600,000 incident events annually) and around the world (∼3.8 million). With every minute that passes without cardiopulmonary resuscitation or defibrillation, the probability of survival decreases by 10%. Preliminary studies suggest that uncrewed aircraft systems, also known as drones, can deliver automated external defibrillators (AEDs) to OHCA victims faster than ground transport and potentially save lives. Objective: To date, the United States (US), Sweden, and Canada have made significant contributions to the knowledge base regarding AED-equipped drones. The purpose of this Special Communication is to explore the challenges and facilitators impacting the progress of AED-equipped drone integration into emergency medicine research and applications in the US, Sweden, and Canada. We also explore opportunities to propel this innovative and important research forward. Evidence review: In this narrative review, we summarize the AED-drone research to date from the US, Sweden, and Canada, including the first drone-assisted delivery of an AED to an OHCA. Further, we compare the research environment, emergency medical systems, and aviation regulatory environment in each country as they apply to OHCA, AEDs, and drones. Finally, we provide recommendations for advancing research and implementation of AED-drone technology into emergency care. Findings: The rates that drone technologies have been integrated into both research and real-life emergency care in each country varies considerably. Based on current research, there is significant potential in incorporating AED-equipped drones into the chain of survival for OHCA emergency response. Comparing the different environments and systems in each country revealed ways that each can serve as a facilitator or barrier to future AED-drone research. Conclusions and relevance: The US, Sweden, and Canada each offers different challenges and opportunities in this field of research. Together, the international community can learn from one another to optimize integration of AED-equipped drones into emergency systems of care.

The impact of double sequential shock timing on outcomes during refractory out-of-hospital cardiac arrest.

BACKGROUND: Animal studies suggest the efficacy of double sequential external defibrillation (DSED) may depend on the interval between the two shocks, or "DSED interval". No human studies have examined this concept. OBJECTIVES: To determine the relationship between DSED interval and termination of ventricular fibrillation (VFT), return of spontaneous circulation (ROSC), survival to hospital discharge, and favourable neurological status (MRS ≤ 2) for patients in refractory VF. METHODS: We performed a retrospective review of adult (≥18 years) out-of-hospital cardiac arrest between January 2015 and May 2022 with refractory VF who received ≥1 DSED shock. DSED interval was divided into four pre-defined categories. We examined the association between DSED interval and patient outcomes using general estimated equation logistic regression or Fisher's exact test. RESULTS: Among 106 included patients, 303 DSED shocks were delivered (median 2, IQR 1-3). DSED intervals of 75-125 ms (OR 0.39, 95% CI 0.16-0.98), 125-500 ms (OR 0.36, 95% CI 0.16-0.82), and >500 ms (OR 0.27, 95% CI 0.11-0.63) were associated with lower probability of VF termination compared to <75 ms interval. DSED interval of >75 ms was associated with lower probability of ROSC compared to <75 ms interval (OR 0.37, 95% CI 0.14-0.98). No association was noted between DSED interval and survival to hospital discharge or neurologic outcome. CONCLUSIONS: Among patients in refractory VF a DSED interval of less than 75 ms was associated with improved rates of VF termination and ROSC. No association was noted between DSED interval and survival to hospital discharge or neurologic outcome.

The relationship between the number of COVID-19 vaccines and infection with Omicron ACE2 inhibition at 18-months post initial vaccination in an adult cohort of Canadian paramedics.

The coronavirus disease 2019 (COVID-19) pandemic, caused by the SARS-CoV-2 virus, has rapidly evolved since late 2019, due to highly transmissible Omicron variants. While most Canadian paramedics have received COVID-19 vaccination, the optimal ongoing vaccination strategy is unclear. We investigated neutralizing antibody (NtAb) response against wild-type (WT) Wuhan Hu-1 and Omicron BA.4/5 lineages based on the number of doses and past SARS-CoV-2 infection, at 18 months post-initial vaccination (with a Wuhan Hu-1 platform mRNA vaccine [BNT162b2 or mRNA-1273]). Demographic information, previous COVID-19 vaccination, infection history, and blood samples were collected from paramedics 18 months post-initial mRNA COVID-19 vaccine dose. Outcome measures were ACE2 percent inhibition against Omicron BA.4/5 and WT antigens. We compared outcomes based on number of vaccine doses (two vs. three) and previous SARS-CoV-2 infection status, using the Mann-Whitney U test. Of 657 participants, the median age was 40 years (IQR 33-50) and 251 (42 %) were females. Overall, median percent inhibition to BA.4/5 and WT was 71.61 % (IQR 39.44-92.82) and 98.60 % (IQR 83.07-99.73), respectively. Those with a past SARS-CoV-2 infection had a higher median percent inhibition to BA.4/5 and WT, when compared to uninfected individuals overall and when stratified by two or three vaccine doses. When comparing two vs. three WT vaccine doses among SARS-CoV-2 negative participants, we did not detect a difference in BA.4/5 percent inhibition, but there was a difference in WT percent inhibition. Among those with previous SARS-CoV-2 infection(s), when comparing two vs. three WT vaccine doses, there was no observed difference between groups. These findings demonstrate that additional Whttps://www.covid19immunitytaskforce.ca/citf-databank/#accessing https://www.covid19immunitytaskforce.ca/citf-databank/#accessinguhan Hu-1 platform mRNA vaccines did not improve NtAb response to BA.4/5, but prior SARS-CoV-2 infection enhances NtAb response.

Wolf Creek XVII Part 5: Mobile AEDs.

Introduction: Millions of out-of-hospital cardiac arrests (OHCA) occur globally each year. Survival after OHCA can be improved with the use of automated external defibrillators (AED). The main strategy for facilitating bystander defibrillation has been fixed-location public access defibrillators (PADs). New strategies of mobile AEDs depart from the model of static PADs and have the potential to address known barriers to early defibrillation and improve outcomes. Methods: Mobile AEDs was one of six focus topics for the Wolf Creek XVII Conference held on June 14-17, 2023, in Ann Arbor, Michigan, USA. Conference invitees included international thought leaders and scientists in the field of cardiac arrest resuscitation from academia and industry. Participants submitted via online survey knowledge gaps, barriers to translation and research priorities for each focus topic. Expert panels used the survey results and their own perspectives and insights to create and present a preliminary unranked list for each category that was debated, revised, and ranked by all attendees to identify the top 5 for each category. Results: Top knowledge gaps center around understanding the impact of mobile AEDs on OHCA outcomes in various settings and the impact of novel AED technologies. Top barriers to translation include questionable public comfort/acceptance, financial/regulatory constraints, and a lack of centralized accountability. Top research priorities focus on understanding the impact of the mobile AED strategies and technologies on time to defibrillation and OHCA outcomes. Conclusion: This work informs research agendas, funding priorities and policy decisions around using mobile AEDs to optimize prehospital response to OHCA.

Predicting survival post-cardiac arrest: An observational cohort study.

Introduction: Over 400,000 out-of-hospital cardiac arrest (OHCA) occur each year in Canada and the United States with less than 10% survival to hospital discharge. Cardiac arrest is a heterogenous condition and patient outcomes are impacted by a multitude of factors. Prognostication is recommended at 72 hours after return of spontaneous circulation (ROSC), however there may be other factors that could predict patient outcome earlier in the post-arrest period. The objective of our study was to develop and internally validate a novel clinical prediction rule to risk stratify patients early in the post-cardiac arrest period. Methods: We performed a retrospective cohort study of adult (≥18 years) post-cardiac arrest patients between 2010 and 2015 from the Epistry Cardiac Arrest database in Toronto. Our primary analysis used ordinal logistic regression to examine neurologic outcome at discharge using the modified Rankin Scale (mRS). Our secondary analysis used logistic regression for neurologic outcome and survival to hospital discharge. Models were internally validated using bootstrap validation. Results: A total of 3432 patients met our inclusion criteria. Our clinical prediction model was able to predict neurologic outcome on an ordinal scale using our predefined variables with an AUC of 0.89 after internal validation. The predictive performance was maintained when examining neurologic outcome as a binary variable and survival to hospital discharge. Conclusion: We were able to develop a model to accurately risk stratify adult cardiac arrest patients early in the post-cardiac arrest period. Future steps are needed to externally validate this model in other healthcare settings.

Prediction models in prehospital and emergency medicine research: How to derive and internally validate a clinical prediction model.

Clinical prediction models are created to help clinicians with medical decision making, aid in risk stratification, and improve diagnosis and/or prognosis. With growing availability of both prehospital and in-hospital observational registries and electronic health records, there is an opportunity to develop, validate, and incorporate prediction models into clinical practice. However, many prediction models have high risk of bias due to poor methodology. Given that there are no methodological standards aimed at developing prediction models specifically in the prehospital setting, the objective of this paper is to describe the appropriate methodology for the derivation and validation of clinical prediction models in this setting. What follows can also be applied to the emergency medicine (EM) setting. There are eight steps that should be followed when developing and internally validating a prediction model: (1) problem definition, (2) coding of predictors, (3) addressing missing data, (4) ensuring adequate sample size, (5) variable selection, (6) evaluating model performance, (7) internal validation, and (8) model presentation. Subsequent steps include external validation, assessment of impact, and cost-effectiveness. By following these steps, researchers can develop a prediction model with the methodological rigor and quality required for prehospital and EM research.

The Effect of Time to Treatment With Antiarrhythmic Drugs on Survival and Neurological Outcomes in Shock Refractory Out-of-Hospital Cardiac Arrest.

OBJECTIVES: Examining the association of time to treatment (drug or placebo) with survival to hospital discharge and neurologic outcome. DESIGN: Post hoc analysis of the Resuscitation Outcomes Consortium Amiodarone, Lidocaine, Placebo randomized controlled trial. SETTING: Emergency medical services enrolled patients with out-of-hospital cardiac arrest (OHCA) at multiple North American sites. PATIENTS: Adults with nontraumatic OHCA and an initial rhythm of ventricular fibrillation or pulseless ventricular tachycardia refractory to at least one defibrillation attempt were included. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We used logistic regression to examine the association of time to treatment with survival to hospital discharge and favorable neurologic status at discharge (modified Rankin Scale ≤ 3) for the three treatment groups including an interaction term between treatment and time to treatment to determine the effect of time on treatment effects. Time to treatment data were available for 2,994 out of 3,026 patients (99%). The proportion of patients who survived to hospital discharge decreased as time to drug administration increased, in amiodarone (odds ratio [OR], 0.91; 95% CI, 0.90-0.93 per min), lidocaine (OR, 0.93; 95% CI, 0.91-0.96), and placebo (OR, 0.91; 95% CI, 0.90-0.93). Comparing amiodarone to placebo, there was improved survival at all times of drug administration (OR, 1.32; 95% CI, 1.05-1.65). Comparing lidocaine to placebo, survival was not different with shorter times to drug administration (< 11 min), whereas survival was higher with lidocaine at longer times to drug administration with an interaction between treatment effect and time to treatment (p = 0.048). Survival with good neurologic outcome showed similar results for all analyses. CONCLUSIONS: Survival and favorable neurologic outcomes decreased with longer times to drug administration. Amiodarone improved survival at all time points whereas lidocaine improved survival only at later time points, compared with placebo.

Ventricular Fibrillation Simulated Electrocardiogram Artifact by a Deep Brain Stimulator.

Deep brain stimulation devices can disrupt cardiac rhythm interpretation by causing electrocardiogram artifact. We report the case of a deep brain stimulating device initiating ventricular fibrillation simulated electrocardiogram artifact in the prehospital setting. Mimicked ventricular fibrillation due to a deep brain stimulator has not been documented, and if unrecognized could influence unwarranted or potentially harmful clinical decisions.

Epinephrine in Out-of-Hospital Cardiac Arrest: A Network Meta-analysis and Subgroup Analyses of Shockable and Nonshockable Rhythms.

BACKGROUND: Epinephrine is the most commonly used drug in out-of-hospital cardiac arrest (OHCA) resuscitation, but evidence supporting its efficacy is mixed. RESEARCH QUESTION: What are the comparative efficacy and safety of standard dose epinephrine, high-dose epinephrine, epinephrine plus vasopressin, and placebo or no treatment in improving outcomes after OHCA? STUDY DESIGN AND METHODS: In this systematic review and network meta-analysis of randomized controlled trials, we searched six databases from inception through June 2022 for randomized controlled trials evaluating epinephrine use during OHCA resuscitation. We performed frequentist random-effects network meta-analysis and present ORs and 95% CIs. We used the the Grading of Recommendations, Assessment, Development, and Evaluation approach to rate the certainty of evidence. Outcomes included return of spontaneous circulation (ROSC), survival to hospital admission, survival to discharge, and survival with good functional outcome. RESULTS: We included 18 trials (21,594 patients). Compared with placebo or no treatment, high-dose epinephrine (OR, 4.27; 95% CI, 3.68-4.97), standard-dose epinephrine (OR, 3.69; 95% CI, 3.32-4.10), and epinephrine plus vasopressin (OR, 3.54; 95% CI, 2.94-4.26) all increased ROSC. High-dose epinephrine (OR, 3.53; 95% CI, 2.97-4.20), standard-dose epinephrine (OR, 3.00; 95% CI, 2.66-3.38), and epinephrine plus vasopressin (OR, 2.79; 95% CI, 2.27-3.44) all increased survival to hospital admission as compared with placebo or no treatment. However, none of these agents may increase survival to discharge or survival with good functional outcome as compared with placebo or no treatment. Compared with placebo or no treatment, standard-dose epinephrine improved survival to discharge among patients with nonshockable rhythm (OR, 2.10; 95% CI, 1.21-3.63), but not in those with shockable rhythm (OR, 0.85; 95% CI, 0.39-1.85). INTERPRETATION: Use of standard-dose epinephrine, high-dose epinephrine, and epinephrine plus vasopressin increases ROSC and survival to hospital admission, but may not improve survival to discharge or functional outcome. Standard-dose epinephrine improved survival to discharge among patients with nonshockable rhythm, but not those with shockable rhythm. TRIAL REGISTRY: Center for Open Science: https://osf.io/arxwq.

Clinical outcomes following out-of-hospital cardiac arrest: The minute-by-minute impact of bystander cardiopulmonary resuscitation.

AIMS: The time-dependent prognostic role of bystander cardiopulmonary resuscitation (CPR) for out-of-hospital cardiac arrest (OHCA) patients has not been described with great precision, especially for neurologic outcomes. Our objective was to assess the association between bystander CPR, emergency medical service (EMS) response time, and OHCA patients' outcomes. METHODS: This cohort study used the Resuscitation Outcomes Consortium Cardiac Epidemiologic Registries. Bystander-witnessed adult OHCA treated by EMS were included. The primary outcome was survival to hospital discharge and secondary outcome was survival with a good neurologic outcome (modified Rankin scale 0-2). Multivariable logistic regression models were used to assess the associations and interactions between bystander CPR, EMS response time and clinical outcomes. RESULTS: Out of 229,637 patients, 41,012 were included (18,867 [46.0%] without bystander CPR and 22,145 [54.0%] with bystander CPR). Bystander CPR was independently associated with higher survival (adjusted odds ratio [AOR] = 1.70 [95%CI 1.61-1.80]) and survival with a good neurologic outcome (AOR = 1.87 [95%CI 1.70-2.06]), while longer EMS response times were independently associated with lower survival to hospital discharge (each additional minute of EMS response time: AOR = 0.92 [95%CI 0.91-0.93], p < 0.001) and lower survival with a good neurologic outcome (AOR = 0.88 [95%CI 0.86-0.89], p < 0.001). There was no interaction between bystander CPR and EMS response time's association with survival (p = 0.12) and neurologic outcomes (p = 0.65). CONCLUSIONS: Although bystander CPR is associated with an immediate increase in odds of survival and of good neurologic outcome for OHCA patients, it does not influence the negative association between longer EMS response time and survival and good neurologic outcome.

Non-Sustained Polymorphic Ventricular Tachycardia Induced by Modified Valsalva in a Pregnant Patient with Supraventricular Tachycardia.

The modified Valsalva maneuver has been promoted as a safe and effective method for the treatment of supraventricular tachycardia. Serious adverse events associated with the modified Valsalva maneuver are not well documented. Here we report a case of non-sustained polymorphic ventricular tachycardia in a pregnant patient associated with the use of the modified Valsalva maneuver by paramedics in the prehospital setting.