Defibrillation Strategies for Refractory Ventricular Fibrillation.

BACKGROUND: Despite advances in defibrillation technology, shock-refractory ventricular fibrillation remains common during out-of-hospital cardiac arrest. Double sequential external defibrillation (DSED; rapid sequential shocks from two defibrillators) and vector-change (VC) defibrillation (switching defibrillation pads to an anterior-posterior position) have been proposed as defibrillation strategies to improve outcomes in patients with refractory ventricular fibrillation. METHODS: We conducted a cluster-randomized trial with crossover among six Canadian paramedic services to evaluate DSED and VC defibrillation as compared with standard defibrillation in adult patients with refractory ventricular fibrillation during out-of-hospital cardiac arrest. Patients were treated with one of these three techniques according to the strategy that was randomly assigned to the paramedic service. The primary outcome was survival to hospital discharge. Secondary outcomes included termination of ventricular fibrillation, return of spontaneous circulation, and a good neurologic outcome, defined as a modified Rankin scale score of 2 or lower (indicating no symptoms to slight disability) at hospital discharge. RESULTS: A total of 405 patients were enrolled before the data and safety monitoring board stopped the trial because of the coronavirus disease 2019 pandemic. A total of 136 patients (33.6%) were assigned to receive standard defibrillation, 144 (35.6%) to receive VC defibrillation, and 125 (30.9%) to receive DSED. Survival to hospital discharge was more common in the DSED group than in the standard group (30.4% vs. 13.3%; relative risk, 2.21; 95% confidence interval [CI], 1.33 to 3.67) and more common in the VC group than in the standard group (21.7% vs. 13.3%; relative risk, 1.71; 95% CI, 1.01 to 2.88). DSED but not VC defibrillation was associated with a higher percentage of patients having a good neurologic outcome than standard defibrillation (relative risk, 2.21 [95% CI, 1.26 to 3.88] and 1.48 [95% CI, 0.81 to 2.71], respectively). CONCLUSIONS: Among patients with refractory ventricular fibrillation, survival to hospital discharge occurred more frequently among those who received DSED or VC defibrillation than among those who received standard defibrillation. (Funded by the Heart and Stroke Foundation of Canada; DOSE VF ClinicalTrials.gov number, NCT04080986.).

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.

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.

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.

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.

Predefibrillation end-tidal CO2 and defibrillation success in out-of-hospital cardiac arrest: an observational cohort study.

BACKGROUND: Predefibrillation end-tidal CO2 (ETCO2) may predict defibrillation success and could guide defibrillation timing in ventricular fibrillation (VF) cardiac arrest. This relationship has only been studied using advanced airways. Our aim was to evaluate this relationship using both basic (bag-valve-mask (BVM)) and advanced airways (supraglottic airways and endotracheal tubes). METHODS: Prehospital patient records and defibrillator files were abstracted for patients with out-of-hospital cardiac arrest in Ontario, Canada, with initial VF cardiac rhythms between 1 January 2018, and 31 December 2019. Analyses assessed the relationship between each predefibrillation ETCO2 reading and defibrillation outcomes at the subsequent 2 min pulse check (ie, VF, asystole, pulseless electrical activity (PEA) or return of spontaneous circulation (ROSC)), accounting for airway types used during resuscitation. Multivariable logistic regression evaluated the association between the first documented predefibrillation ETCO2 and postshock VF termination or ROSC. RESULTS: Of 269 cases abstracted, 153 had predefibrillation ETCO2 measurements and were included in the study. Among these cases, 904 shocks were delivered and 44.4% (n=401) had predefibrillation ETCO2 measured. The first ETCO2 reading was more often from BVM (n=134) than advanced airways (n=19). ETCO2 readings were lower when measured through BVM versus advanced airways (30.5 mm Hg (4.06 kPa) (±14.4 mm Hg (1.92 kPa)) vs 42.1 mm Hg (5.61 kPa) (±22.5 mm Hg (3.00 kPa)), adjANOVA p<0.01). Of all shocks with ETCO2 reading (n=401), no difference in preshock ETCO2 was found for subsequent shocks that resulted in persistent VF (32.2 mm Hg (4.29 kPa) (±15.8 mm Hg (2.11 kPa))), PEA (32.8 mm Hg (4.37 kPa) (±17.1 mm Hg (2.30 kPa))), asystole (32.4 mm Hg (4.32 kPa) (±20.6 mm Hg (2.75 kPa))) or ROSC (32.5 mm Hg (4.33 kPa) (±15.3 mm Hg (2.04 kPa))), analysis of variance p=0.99. In the multivariate analysis using the initial predefibrillation ETCO2, there was no association with VF termination on the subsequent shock (adjusted OR (adjOR) 0.99, 95% CI 0.97 to 1.02, p=0.57) or ROSC (adjOR 1.00, 95% CI 0.97 to 1.03, p=0.94) when evaluated as a continuous or categorical variable. CONCLUSION: Predefibrillation ETCO2 measurement is not associated with VF termination or ROSC when basic and advanced airways are included in the analysis. The role of predefibrillation ETCO2 requires careful consideration of the type of airway used during resuscitation.

Gender-Based Differences in Outcomes Among Resuscitated Patients With Out-of-Hospital Cardiac Arrest.

BACKGROUND: Studies examining gender-based differences in outcomes of patients experiencing out-of-hospital cardiac arrest have demonstrated that, despite a higher likelihood of return of spontaneous circulation, women do not have higher survival. METHODS: Patients successfully resuscitated from out-of-hospital cardiac arrest enrolled in the CCC trial (Trial of Continuous or Interrupted Chest Compressions during CPR) were included. Hierarchical multivariable logistic regression models were constructed to evaluate the association between gender and survival after adjustment for age, gender, cardiac arrest rhythm, witnessed status, bystander cardiopulmonary resuscitation, episode location, epinephrine dose, emergency medical services response time, and duration of resuscitation. Do not resuscitate (DNR) and withdrawal of life-sustaining therapy (WLST) order status were used to assess whether differences in postresuscitation outcomes were modified by baseline prognosis. The analysis was replicated among ALPS trial (Amiodarone, Lidocaine, or Placebo in Out-of-Hospital Cardiac Arrest) participants. RESULTS: Among 4875 successfully resuscitated patients, 1825 (37.4%) were women and 3050 (62.6%) were men. Women were older (67.5 versus 65.3 years), received less bystander cardiopulmonary resuscitation (49.1% versus 54.9%), and had a lower proportion of cardiac arrests that were witnessed (55.1% versus 64.5%) or had shockable rhythm (24.3% versus 44.6%, P<0.001 for all). A significantly higher proportion of women received DNR orders (35.7% versus 32.1%, P=0.009) and had WLST (32.8% versus 29.8%, P=0.03). Discharge survival was significantly lower in women (22.5% versus 36.3%, P<0.001; adjusted odds ratio, 0.78 [95% CI, 0.66-0.93]; P=0.005). The association between gender and survival to discharge was modified by DNR and WLST order status such that women had significantly reduced survival to discharge among patients who were not designated DNR (31.3% versus 49.9%, P=0.005; adjusted odds ratio, 0.74 [95% CI, 0.60-0.91]) or did not have WLST (32.3% versus 50.7%, P=0.002; adjusted odds ratio, 0.73 [95% CI, 0.60-0.89]). In contrast, no gender difference in survival was noted among patients receiving a DNR order (6.7% versus 7.4%, P=0.90) or had WLST (2.8% versus 2.4%, P=0.93). Consistent patterns of association between gender and postresuscitation outcomes were observed in the secondary cohort. CONCLUSIONS: Among patients resuscitated after experiencing out-of-hospital cardiac arrest, discharge survival was significantly lower in women than in men, especially among patients considered to have a favorable prognosis.

A Higher Antibody Response Is Generated With a 6- to 7-Week (vs Standard) Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Vaccine Dosing Interval.

The optimal dosing interval for severe acute respiratory syndrome coronavirus 2 vaccines remains controversial. In this prospective study, we compared serology results of paramedics vaccinated with mRNA vaccines at the recommended short (17-28 days) vs long (42-49 days) interval. We found that a long dosing interval resulted in higher spike, receptor binding domain, and spike N terminal domain antibody concentrations.

Rationale, development and implementation of the ReACanROC registry for out-of-hospital cardiac arrests in France and Canada.

France and Canada prehospital systems and care delivery in out-of-hospital cardiac arrests (OHCAs) show substantial differences. This article aims to describe the rationale, design, implementation and expected research implications of the international, population-based, France-Canada registry for OHCAs, namely ReACanROC, which is built from the merging of two nation-wide, population-based, Utstein-style prospectively implemented registries for OHCAs attended to by emergency medical services. Under the supervision of an international steering committee and research network, the ReACanROC dataset will be used to run in-depth analyses on the differences in organisational, practical and geographic predictors of survival after OHCA between France and Canada. ReACanROC is the first Europe-North America registry ever created to meet this goal. To date, it covers close to 80 million people over the two countries, and includes approximately 200 000 cases over a 10-year period.

Multi-centre implementation of an Educational program to improve the Cardiac Arrest diagnostic accuracy of ambulance Telecommunicators and survival outcomes for sudden cardiac arrest victims: the EduCATe study design and methodology.

BACKGROUND: Sudden cardiac death remains a leading cause of mortality in Canada, resulting in more than 35,000 deaths annually. Most cardiac arrest victims collapse in their own home (85% of the time) and 50% are witnessed by a family member or bystander. Survivors have a quality of life similar to the general population, but the overall survival rate for out-of-hospital cardiac arrest (OHCA) rarely exceeds 8%. Victims are almost four times more likely to survive when receiving bystander CPR, but bystander CPR rates have remained low in Canada over the past decade, not exceeding 15-25% until recently. Telecommunication-assisted CPR instructions have been shown to significantly increase bystander CPR rates, but agonal breathing may be misinterpreted as a sign of life by 9-1-1 callers and telecommunicators, and is responsible for as much as 50% of missed OHCA diagnoses. We sought to improve the ability and speed with which ambulance telecommunicators can recognize OHCA over the phone, initiate timely CPR instructions, and improve survival. METHODS: In this multi-center national study, we will implement and evaluate an educational program developed for ambulance telecommunicators using a multiple baseline interrupted time-series design. We will compare outcomes 12 months before and after the implementation of a 20-min theory-based educational video addressing barriers to recognition of OHCA while in the presence of agonal breathing. Participating Canadian sites demonstrated prior ability to collect standardized data on OHCA. Data will be collected from eligible 9-1-1 recordings, paramedic documentation and hospital medical records. Eligible cases will include suspected or confirmed OHCA of presumed cardiac origin in patients of any age with attempted resuscitation. DISCUSSION: The ability of telecommunication-assisted CPR instructions to improve bystander CPR and survival rates for OHCA victims is undeniable. The ability of telecommunicators to recognize OHCA over the phone is unequivocally impeded by relative lack of training on agonal breathing, and reluctance to initiate CPR instructions when in doubt. Our pilot data suggests the potential impact of this project will be to increase absolute OHCA recognition and bystander CPR rates by at least 10%, and absolute out-of-hospital cardiac arrest survival by 5% or more. TRIAL REGISTRATION: Prospectively registered on March 28, 2019 at ClinicalTrials.gov identifier: NCT03894059 .

Screening strategies to identify sepsis in the prehospital setting: a validation study.

BACKGROUND: In the prehospital setting, differentiating patients who have sepsis from those who have infection but no organ dysfunction is important to initiate sepsis treatments appropriately. We aimed to identify which published screening strategies for paramedics to use in identifying patients with sepsis provide the most certainty for prehospital diagnosis. METHODS: We identified published strategies for screening by paramedics through a literature search. We then conducted a validation study in Alberta, Canada, from April 2015 to March 2016. For adult patients (≥ 18 yr) who were transferred by ambulance, we linked records to an administrative database and then restricted the search to patients with infection diagnosed in the emergency department. For each patient, the classification from each strategy was determined and compared with the diagnosis recorded in the emergency department. For all strategies that generated numeric scores, we constructed diagnostic prediction models to estimate the probability of sepsis being diagnosed in the emergency department. RESULTS: We identified 21 unique prehospital screening strategies, 14 of which had numeric scores. We linked a total of 131 745 eligible patients to hospital databases. No single strategy had both high sensitivity (overall range 0.02-0.85) and high specificity (overall range 0.38-0.99) for classifying sepsis. However, the Critical Illness Prediction (CIP) score, the National Early Warning Score (NEWS) and the Quick Sepsis-Related Organ Failure Assessment (qSOFA) score predicted a low to high probability of a sepsis diagnosis at different scores. The qSOFA identified patients with a 7% (lowest score) to 87% (highest score) probability of sepsis diagnosis. INTERPRETATION: The CIP, NEWS and qSOFA scores are tools with good predictive ability for sepsis diagnosis in the prehospital setting. The qSOFA score is simple to calculate and may be useful to paramedics in screening patients with possible sepsis.

Call 911: Lower Ambulance Utilization Among Young Adults, Especially Women, with Stroke.

BACKGROUND: Delayed presentation to the emergency department influences acute stroke care and can result in worse outcomes. Despite public health messaging, many young adults consider stroke as a disease of older people. We determined the differences in ambulance utilization and delays to hospital presentation between women and men as well as younger (18-44 years) versus older (≥45 years) patients with stroke. METHODS: We conducted a population-based retrospective study using national administrative health data from the Canadian Institute of Health Information databases and examined data between 2003 and 2016 to compare ambulance utilization and time to hospital presentation across sex and age. RESULTS: Young adults account for 3.9% of 463,310 stroke/transient ischemic attack/hemorrhage admissions. They have a higher proportion of hemorrhage (37% vs. 15%) and fewer ischemic events (50% vs. 68%) compared with older patients. Younger patients are less likely to arrive by ambulance (62% vs. 66%, p < 0.001), with younger women least likely to use ambulance services (61%) and older women most likely (68%). Median stroke onset to hospital arrival times were 7 h for older patients and younger men, but 9 h in younger women. There has been no improvement among young women in ambulance utilization since 2003, whereas ambulance use increased in all other groups. CONCLUSIONS: Younger adults, especially younger women, are less likely to use ambulance services, take longer to get to hospital, and have not improved in utilization of emergency services for stroke over 13 years. Targeted public health messaging is required to ensure younger adults seek emergency stroke care.

Successful Resuscitation from Refractory Ventricular Fibrillation by BLS Providers Employing Double Sequential External Defibrillation: A Case Report.

Double sequential external defibrillation (DSED) is a novel treatment option for cardiac arrest patients in refractory ventricular fibrillation (VF). There is limited research, however, examining the efficacy of this treatment in clinical practice. Previous research is further confounded by the use of other treatments such as advanced cardiac life support medications. We present the case of the successful use of DSED for refractory out-of-hospital cardiac arrest without the use of advanced life support care.

Assessing Severity of Illness in Patients Transported to Hospital by Paramedics: External Validation of 3 Prognostic Scores.

Introduction: Emergency Medical Services (EMS) are the first healthcare contact for the majority of severely ill patients. Physiologic measures collected by EMS, when incorporated into a prognostic score, may provide important information on patient illness severity. This study compares the predictive ability of 3 common prognostic scores for predicting clinical outcomes in EMS patients. Methods: Discrimination and calibration for predicting the primary outcome of hospital mortality, and secondary outcomes of 2-day mortality and ED disposition, were assessed for each of the scores using a one-year cohort of patients transported to hospital by EMS in Alberta, Canada. For each score, binary logistic regression was used to predict hospital mortality and 2-day mortality and ordinal logistic regression was used to predict ED disposition. Discrimination for each outcome was assessed using C-statistics, and calibration was assessed using calibration curves comparing predicted versus observed outcomes. Results: The Critical Illness Prediction [CIP], Modified Early Warning Score [MEWS], and National Early Warning Score [NEWS] were compared using 121,837 adult patients who were transported by paramedics. All scores had good discrimination for hospital mortality (C-statistic CIP: 0.79, MEWS: 0.71, NEWS: 0.78) and 2-day mortality (CIP:0.85, MEWS: 0.80, NEWS:0.85) but only moderate discrimination for ED disposition (CIP: 0.68, MEWS: 0.61, NEWS: 0.66). Calibration was reliable for hospital mortality in all scores but over-predicted risk for 2-day mortality at higher scores. Overall, the CIP score had the best discrimination, good calibration, and the greatest range of predicted probabilities (0.01 at a CIP score of 0 to 0.92 at a CIP score of 8) for hospital mortality. Conclusions: Prognostic scores using physiologic measures assessed by paramedics have good predictive ability for hospital mortality. These scores, particularly the CIP score, may be considered as a tool for mortality risk stratification or as a general measure of illness severity for patients included in EMS studies.

Strategy to Identify Paramedic Transported Sepsis Cases in an Emergency Department Administrative Database.

Background: To evaluate a new strategy for identifying sepsis in Emergency Department (ED) patients that combines administrative diagnosis codes with clinical information from the point of first contact. Methods: This study linked clinical data from adult patients transported by a provincial Emergency Medical Services (EMS) system to ED and inpatient administrative databases. Sepsis cases were identified by searching ED databases for diagnosis codes consistent with infection and organ dysfunction. Organ dysfunction was further assessed using a partial Sequential Organ Failure Assessment (SOFA) score derived from EMS clinical information. Reliability was evaluated by comparing patients' ED diagnosis codes (ICD-10CA) to their inpatient diagnosis codes; criterion validity by comparing cases classified by the new strategy to an existing inpatient administrative algorithm; and construct validity by assessing for clinical characteristics typically associated with sepsis (e.g., mortality). Results: A total of 43,297 patients were included. ED infection codes were more reliable for classifying patients with infection than using ED sepsis codes alone (proportion of agreement with inpatient codes 79% vs. 74%; p-value < 0.001). The novel strategy requiring the presence of an infection code and either an organ dysfunction code or 2 or more SOFA points from EMS clinical information identified 1,379 more ED patients as having sepsis than the inpatient algorithm. These patients had high mortality supporting construct validity. Conclusions: Incorporation of a broader range of diagnostic codes and linking to an electronic database to obtain initial clinical information for the assessment of organ dysfunction improves reliability, criterion, and construct validity for identifying sepsis in ED patients.

Impact of Pit-Crew Cardiopulmonary Resuscitation on Out-of-Hospital Cardiac Arrest in Saskatoon.

BACKGROUND: In the prehospital setting, pit-crew models of cardiopulmonary resuscitation (CPR) have shown improvements in survival after out-of-hospital cardiac arrest (OHCA). Certain districts in North America have adopted this model, including Saskatoon, Saskatchewan, Canada. OBJECTIVES: Our objectives were to determine whether pit-crew CPR has an impact on survival to discharge after OHCA in Saskatoon, Canada. METHODS: This was a retrospective pre- and postintervention study. All adult patients who had an OHCA between January 1, 2011 and December 31, 2017 of presumed cardiac origin, in which the resuscitation attempt included CPR by trained prehospital responders, were considered for analysis. Our primary outcome was survival to discharge. Survival to admission and return of spontaneous circulation were secondary outcomes. RESULTS: There were 860 OHCAs considered for our study. After 46 exclusions there were 442 in the non-pit-crew group (average age 63.7 years; 64.5% male) and 372 in the pit-crew group (average age 63.5 years; 67.5% male). Survival to discharge after an OHCA was 10.4% (95% confidence interval 7.7-13.6%) in the non-pit-crew group and 12.4% (95% CI 9.2-16.2%) in the pit-crew group, which did not meet statistical significance. Return of spontaneous circulation and survival to admission were 48.4% and 31.3%, respectively, in the non-pit-crew group and 46.7% and 32.3%, respectively, in the pit-crew group. CONCLUSIONS: In our study, implementation of a pit-crew CPR model was not associated with an improvement in survival to discharge after OHCA.

Time to Epinephrine Administration and Survival From Nonshockable Out-of-Hospital Cardiac Arrest Among Children and Adults.

BACKGROUND: Previous studies have demonstrated that earlier epinephrine administration is associated with improved survival from out-of-hospital cardiac arrest (OHCA) with shockable initial rhythms. However, the effect of epinephrine timing on patients with nonshockable initial rhythms is unclear. The objective of this study was to measure the association between time to epinephrine administration and survival in adults and children with emergency medical services (EMS)-treated OHCA with nonshockable initial rhythms. METHODS: We performed a secondary analysis of OHCAs prospectively identified by the Resuscitation Outcomes Consortium network from June 4, 2011, to June 30, 2015. We included patients of all ages with an EMS-treated OHCA and an initial nonshockable rhythm. We excluded those with return of spontaneous circulation in <10 minutes. We conducted a subgroup analysis involving patients <18 years of age. The primary exposure was time (minutes) from arrival of the first EMS agency to the first dose of epinephrine. Secondary exposure was time to epinephrine dichotomized as early (<10 minutes) or late (≥10 minutes). The primary outcome was survival to hospital discharge. We adjusted for Utstein covariates and Resuscitation Outcomes Consortium study site. RESULTS: From 55 568 EMS-treated OHCAs, 32 101 patients with initial nonshockable rhythms were included. There were 12 238 in the early group, 14 517 in the late group, and 5346 not treated with epinephrine. After adjusting for potential confounders, each minute from EMS arrival to epinephrine administration was associated with a 4% decrease in odds of survival for adults, odds ratio=0.96 (95% confidence interval, 0.95-0.98). A subgroup analysis (n=13 290) examining neurological outcomes showed a similar association (adjusted odds ratio, 0.94 per minute; 95% confidence interval, 0.89-0.98). When epinephrine was given late in comparison with early, odds of survival were 18% lower (odds ratio, 0.82; 95% confidence interval, 0.68-0.98). In a pediatric analysis (n=595), odds of survival were 9% lower (odds ratio, 0.91; 95% confidence interval, 0.81-1.01) for each minute delay in epinephrine. CONCLUSIONS: Among OHCAs with nonshockable initial rhythms, the majority of patients were administered epinephrine >10 minutes after EMS arrival. Each minute delay in epinephrine administration was associated with decreased survival and unfavorable neurological outcomes. EMS agencies should consider strategies to reduce epinephrine administration times in patients with initial nonshockable rhythms.

Optimizing a Drone Network to Deliver Automated External Defibrillators.

BACKGROUND: Public access defibrillation programs can improve survival after out-of-hospital cardiac arrest, but automated external defibrillators (AEDs) are rarely available for bystander use at the scene. Drones are an emerging technology that can deliver an AED to the scene of an out-of-hospital cardiac arrest for bystander use. We hypothesize that a drone network designed with the aid of a mathematical model combining both optimization and queuing can reduce the time to AED arrival. METHODS: We applied our model to 53 702 out-of-hospital cardiac arrests that occurred in the 8 regions of the Toronto Regional RescuNET between January 1, 2006, and December 31, 2014. Our primary analysis quantified the drone network size required to deliver an AED 1, 2, or 3 minutes faster than historical median 911 response times for each region independently. A secondary analysis quantified the reduction in drone resources required if RescuNET was treated as a large coordinated region. RESULTS: The region-specific analysis determined that 81 bases and 100 drones would be required to deliver an AED ahead of median 911 response times by 3 minutes. In the most urban region, the 90th percentile of the AED arrival time was reduced by 6 minutes and 43 seconds relative to historical 911 response times in the region. In the most rural region, the 90th percentile was reduced by 10 minutes and 34 seconds. A single coordinated drone network across all regions required 39.5% fewer bases and 30.0% fewer drones to achieve similar AED delivery times. CONCLUSIONS: An optimized drone network designed with the aid of a novel mathematical model can substantially reduce the AED delivery time to an out-of-hospital cardiac arrest event.

Trial of Continuous or Interrupted Chest Compressions during CPR.

BACKGROUND: During cardiopulmonary resuscitation (CPR) in patients with out-of-hospital cardiac arrest, the interruption of manual chest compressions for rescue breathing reduces blood flow and possibly survival. We assessed whether outcomes after continuous compressions with positive-pressure ventilation differed from those after compressions that were interrupted for ventilations at a ratio of 30 compressions to two ventilations. METHODS: This cluster-randomized trial with crossover included 114 emergency medical service (EMS) agencies. Adults with non-trauma-related cardiac arrest who were treated by EMS providers received continuous chest compressions (intervention group) or interrupted chest compressions (control group). The primary outcome was the rate of survival to hospital discharge. Secondary outcomes included the modified Rankin scale score (on a scale from 0 to 6, with a score of ≤3 indicating favorable neurologic function). CPR process was measured to assess compliance. RESULTS: Of 23,711 patients included in the primary analysis, 12,653 were assigned to the intervention group and 11,058 to the control group. A total of 1129 of 12,613 patients with available data (9.0%) in the intervention group and 1072 of 11,035 with available data (9.7%) in the control group survived until discharge (difference, -0.7 percentage points; 95% confidence interval [CI], -1.5 to 0.1; P=0.07); 7.0% of the patients in the intervention group and 7.7% of those in the control group survived with favorable neurologic function at discharge (difference, -0.6 percentage points; 95% CI, -1.4 to 0.1, P=0.09). Hospital-free survival was significantly shorter in the intervention group than in the control group (mean difference, -0.2 days; 95% CI, -0.3 to -0.1; P=0.004). CONCLUSIONS: In patients with out-of-hospital cardiac arrest, continuous chest compressions during CPR performed by EMS providers did not result in significantly higher rates of survival or favorable neurologic function than did interrupted chest compressions. (Funded by the National Heart, Lung, and Blood Institute and others; ROC CCC ClinicalTrials.gov number, NCT01372748.).