High risk neighbourhoods: The effect of neighbourhood level factors on cardiac arrest incidence.

BACKGROUND: Numerous studies have shown significant neighbourhood level variation in out-of-hospital cardiac arrest (OHCA) incidence rates, however, few have provided an explanation for these disparities beyond traditional socioeconomic measures. METHODS: This was a retrospective study using data from a large population-based OHCA database (Rescu Epistry). We included adults ≥20 years who experienced a non-traumatic OHCA and were treated by emergency medical services within Toronto, Canada between 2006-2012. The residential address of each OHCA patient was spatially mapped to 1 of 517 Toronto census tracts (CTs). Patient and CT level characteristics were included in multivariate regression models to assess their association with OHCA incidence per 100,000 persons. RESULTS: Of the 7775 OHCAs occurring in the study area, 7692 (98.9%) were eligible for inclusion. OHCA incidence rates varied widely across CT quintiles, with rates differing almost 4-fold (109.1 per 100,000 yearly Q5 most deprived vs. 30.0 per 100,000 yearly Q1 least deprived p < 0.0001). Numerous areas of high incidence adjacent to areas of low incidence were observed. After adjustment, all variables except the Activity Friendly Index showed highly significant linear trends, with increasing age, sex ratio, diabetes prevalence, material deprivation and ethnic concentration being independently associated with increasing OHCA incidence. In contrast, we did not observe a linear relationship between high OHCA incidence and median household income. CONCLUSIONS: This study showed almost 4-fold OHCA incidence variability across a large metropolitan area. This variability was partially correlated with population and health data, but not typical socioeconomic predictors, such as median household income.

Patient and hospital factors predict use of coronary angiography in out-of-hospital cardiac arrest patients.

AIM: To describe the association between patient- and hospital-level factors and coronary angiography among patients who suffer out-of-hospital cardiac arrest (OHCA). METHODS: A population-based retrospective cohort study using data from 28 hospitals in Southern Ontario between March 1, 2010 and December 31, 2014. We included consecutive adult patients with atraumatic, OHCA, who achieved return of spontaneous circulation, and were alive at least six hours after hospital arrival. Multilevel logistic regression was used to measure the relationship between patient- and hospital-level covariates and receipt of coronary angiography. RESULTS: Among 2578 consecutive patients, the mean age was 67(±15), 69% were male, 49% had a shockable initial cardiac arrest rhythm and 84% were comatose at hospital admission. Overall, 33% of the study population received coronary angiography. This varied markedly by hospital of first assessment (13%-70%). Factors associated with receiving coronary angiography included ST-segment elevation (OR = 21.30, CI95 16.17-28.04), a shockable initial cardiac rhythm (OR = 5.00, CI95 3.70-6.75), bystander AED use (OR = 2.51, CI95 1.49-4.23), EMS-witnessed arrest (OR = 2.49, CI95 1.62-3.81), initial admission to a PCI center (OR = 2.94, CI95 1.66-5.21), age (OR = 1.04, CI95 1.02-1.07 for age <55, OR = 0.91, CI95 0.88-0.94 for age ≥55), and pre-hospital ROSC (OR = 1.59, CI95 1.06-2.39). CONCLUSION: We identified patient- and hospital-level factors that explain some of the variability in the use of coronary angiography for OHCA. Future work should determine which post arrest patients will benefit most from urgent coronary angiography and evaluate knowledge translation strategies to ensure consistent delivery of best practices.

Incidence, outcomes and guideline compliance of out-of-hospital maternal cardiac arrest resuscitations: A population-based cohort study.

BACKGROUND: Incidence and survival rates after cardiac arrest among pregnant women are reported for in-hospital cardiac arrests; the incidence and outcomes of maternal out-of-hospital cardiac arrest (OHCA) are unknown. Current cardiopulmonary resuscitation guidelines contain recommendations specific to this population; compliance with these has not been investigated. OBJECTIVE: To report maternal OHCA incidence, outcomes, and compliance with recommended treatment guidelines. METHODS: A population-based cohort study of consecutive maternal OHCAs from 2010 to 2014. Census data of all women of childbearing age provided the comparison. Resuscitation performance was measured against the 2010 American Heart Association (AHA) Guidelines. RESULTS: Six maternal OHCAs were identified among 1085 OHCAs occurring in females of child bearing age (15-49) years; Incidence 1.71 per 100,000 pregnant women (95% CI 0.21 to 6.18) vs. 20.18 OHCAs per 100,000 females of child bearing age (95% CI, 18 to 22.62) p < 0.0001. Survival to hospital discharge was 16.7% (95% CI 3.0, 56.4%) after maternal OHCA vs. 6.8% (95% CI 5.4, 8.4) p < 0.0001 after OHCA in all females of childbearing age, and neonatal survival was 33.3% (95% CI 9.7, 70%). CPR quality metric compliance averaged 83% (range 75% to 100%); compliance with pregnancy-specific resuscitation guidelines ranged from 0% (uterine displacement) to 100% (intravenous line insertion above diaphragm and prehospital maternal team activation). CONCLUSION: The incidence of maternal OHCA was 1.71:100,000. Survival was higher after maternal OHCA than after OHCA of non-pregnant females of childbearing age. Pregnancy-specific guideline compliance was low suggesting a need for training and better documentation to improve outcomes in these rare events.

Improving Temporal Trends in Survival and Neurological Outcomes After Out-of-Hospital Cardiac Arrest.

BACKGROUND: Considerable effort has gone into improving outcomes from out-of-hospital cardiac arrest (OHCA). Studies suggest that survival is improving; however, prior studies had insufficient data to pursue the relationship between markers of guideline compliance and temporal trends. The objective of the study was to evaluate trends in OHCA survival over an 8-year period that included the implementation of the 2005 and 2010 international cardiopulmonary resuscitation (CPR) guidelines. METHODS AND RESULTS: This was a population-based cohort study of all consecutive treated OHCA patients of presumed cardiac cause between 2006 and 2013 in the City of Toronto, Canada, and surrounding regions. Temporal changes were measured by χ2 trend test. The association between year of the OHCA and survival was evaluated using logistic regression and joinpoint analysis. A total of 23 619 patients with OHCA met study inclusion criteria. During the study period, survival to hospital discharge doubled (4.8% in 2006 to 9.4% in 2013; P<0.0001), and survival with good neurological outcome increased (6.2% in 2010 to 8.5% in 2013; P=0.005). Improvements occurred in the rates of bystander CPR and automated external defibrillator application, high-quality CPR metrics, and in-hospital targeted temperature management. After adjusting for the Utstein variables, survival to hospital discharge (odds ratio, 1.12; 95% confidence interval, 1.09-1.15) and survival with good neurological outcome (odds ratio, 1.13; 95% confidence interval, 1.05-1.22) increased with each year of study. CONCLUSIONS: Survival after OHCA has improved over time. This trend was associated with improved rates of bystander CPR, automated external defibrillator use, high-quality CPR metrics, and in-hospital targeted temperature management. The results suggest that multiple factors, each improving over time, may have contributed to the observed increase in survival.

Implantable Cardioverter Defibrillator Implantation Rates After Out of Hospital Cardiac Arrest: Are the Rates Guideline-Concordant?

BACKGROUND: Clinical practice guidelines recommend implantable cardioverter defibrillators (ICDs) for the secondary prevention of sudden death after a cardiac arrest not from a reversible cause, but "real world" implantation rates are not well described. METHODS: Adults with out of hospital cardiac arrest attended by Emergency Medical Services are captured in the Toronto Regional RescuNET database. We analyzed those who survived to hospital discharge and collected data on age, sex, initial rhythm, ST-elevation myocardial infarction (STEMI) on presenting electrocardiogram (ECG), in-hospital revascularization, neurologic status (Modified Rankin Scale [MRS]) at discharge, and admission hospital type. To estimate 'indicated' ICD implantation rates, "likely ICD-eligible" patients were defined as having an initial shockable rhythm, no STEMI on presenting ECG, no revascularization, and good neurologic status (MRS 0-3). "Not likely ICD-eligible" patients were defined as having a STEMI on presenting ECG, revascularization, or poor neurologic status (MRS 4-5). RESULTS: In the 1238 adults (2011-2014) analyzed, the overall ICD implantation rate was 23.9%. Two hundred fifty-six patients were "likely ICD-eligible," of whom 146 (57.0%) received an ICD. The implantation rate for "not likely ICD-eligible" patients was 16.7% (112 of 670). ICD eligibility could not be determined for 312 patients, of whom 38 (12.2%) received an ICD. Admission to a hospital with ICD implantation facilities was associated with a higher probability of ICD implantation (odds ratio, 2.85; 95% confidence interval, 1.40-5.82). CONCLUSIONS: Postcardiac arrest ICD implantation rates in eligible patients are lower than expected. Implementation strategies to monitor guideline adherence after out of hospital cardiac arrest are warranted.

CPR quality during out-of-hospital cardiac arrest transport.

BACKGROUND: Previous studies have demonstrated significant associations between cardiopulmonary resuscitation (CPR) quality metrics and survival to hospital discharge. No adequately powered study has explored the relationship between location of resuscitation (scene vs. transport) and CPR quality. METHODS: We analyzed CPR quality data from treated adult OHCA occurring over a 40 month period beginning January 1, 2013 from the Rescu Epistry-cardiac arrest database. High quality CPR was defined as chest compression fraction (CCF) >0.7, compression rate >100/min and compression depth >5.0cm. Our primary objective was to compare the proportion of resuscitations for which all CPR quality benchmarks were met between scene and transport phases of resuscitation. Our secondary objectives were to compare the quality of CPR between the scene phase and transport phase of resuscitation. RESULTS: The proportion of patients with high quality CPR was similar on scene compared to during transport (45.8% vs. 42.5%; ∆ 3.3 %; 95% CI: -1.4, 8.1). Regarding individual CPR metrics, median compression rate was higher on scene compared to transport (105.8 compressions per minute (cpm) vs. 102.0cpm; ∆ 3.8cpm; 95% CI: 2.5, 4.0), while median compression depth (5.56cm vs. 5.33cm; ∆ 0.23cm; 95% CI: 0.12, 0.26) and median CCF (0.95 vs. 0.87; ∆ 0.08; 95% CI: 0.07, 0.08) were higher during the transport phase. CONCLUSIONS: High quality CPR metrics were similar in both (scene and transport) locations of resuscitation. These results suggest that high quality, manual compressions can be performed by prehospital providers regardless of location.

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.

The association between manual mode defibrillation, pre-shock pause duration and appropriate shock delivery when employed by basic life support paramedics during out-of-hospital cardiac arrest.

BACKGROUND: Pre-shock pause duration of <20s is associated with improved survival after cardiac arrest. Manual mode defibrillation has been associated with the shortest duration of pre-shock pause but is largely practiced by advanced life support paramedics (ALS) whereas defibrillator only paramedics (basic life support or BLS) routinely use the defibrillator in automatic mode. OBJECTIVE: We sought to explore the relationship between manual mode defibrillation, pre-shock pause duration and rate of inappropriate shocks when defibrillation is provided by ALS vs. BLS trained in manual mode defibrillation. METHODS: We performed a retrospective review of all treated non-traumatic adult out-of-hospital cardiac arrest (OHCA) presenting in a shockable rhythm over a one year period beginning January 1, 2012. Our primary outcome measure was the proportion of manual mode shocks delivered by BLS with pre-shock pause duration of <20s when compared to ALS. Our secondary outcome measures were the duration of pre-, post- and peri-shock pause and the proportion of appropriate shocks (defined as correct identification and shock delivery to patients in a shockable rhythm) delivered by either level of paramedic. This study had a power of 90% to detect an absolute difference of 15% between paramedic levels in proportion of shocks delivered with pre-shock pause duration <20s. RESULTS: Among 2019 treated OHCA, 335 (20%) presented in a shockable rhythm. Manual defibrillation was performed in 155 (46%) of these cases (196 shocks by ALS, 143 shocks by BLS). There were no differences in the proportion of shocks delivered with pre-shock pause duration <20s (ALS 82.8% vs. BLS 84.8%, p=.65) nor pre-shock pause duration (s) (median, Q1, Q3); ALS: 12.0 (7.0,17.0) vs. BLS: 11.0 (5.0,17.0), p=.13 while BLS had a significantly shorter peri-shock pause duration (s) (median, Q1, Q3); ALS: 17.0 (12.0, 23.0) vs. BLS: 15.0 (9.0, 22.0), p=.05. There were no differences in the rate of inappropriate shocks (ALS 1.0% vs. BLS 0.7%), p=1.0 between levels of paramedics. CONCLUSIONS: Manual mode defibrillation by BLS paramedics produced similar measures of pre-shock pause duration when compared to ALS paramedics without increasing the incidence of inappropriate shocks. Further study is required to determine the potential impact of BLS manual mode defibrillation on clinical outcomes.

Improving use of targeted temperature management after out-of-hospital cardiac arrest: a stepped wedge cluster randomized controlled trial.

RATIONALE: International guidelines recommend use of targeted temperature management following resuscitation from out-of-hospital cardiac arrest. This treatment, however, is often neglected or delayed. OBJECTIVE: To determine whether multifaceted quality improvement interventions would increase the proportion of eligible patients receiving successful targeted temperature management. SETTING: A network of 6 regional emergency medical services systems and 32 academic and community hospitals serving a population of 8.8 million people providing post arrest care to out-of-hospital cardiac arrest. INTERVENTIONS: Comparing interventions improve the implementation of targeted temperature management post out-of-hospital cardiac arrest through passive (education, generic protocol, order set, local champions) versus additional active quality improvement interventions (nurse specialist providing site-specific interventions, monthly audit-feedback, network educational events, internet blog) versus no intervention (baseline standard of care). MEASUREMENTS AND MAIN RESULTS: The primary process outcome was proportion of eligible patients receiving successful targeted temperature management, defined as a target temperature of 32-34ºC within 6 hours of emergency department arrival. Secondary clinical outcomes included survival and neurological outcome at hospital discharge. Four thousand three hundred seventeen out-of-hospital cardiac arrests were transported to hospital; 1,737 (40%) achieved spontaneous circulation, and 934 (22%) were eligible for targeted temperature management. After accounting for secular trends, patients admitted during the passive quality improvement phase were more likely to achieve successful targeted temperature management compared with those admitted during the baseline period (25.7% passive vs 9.0% baseline; odds ratio, 2.76; 95% CI, 1.76-4.32; p < 0.001). Active quality improvement interventions conferred no additional improvements in rates of successful targeted temperature management (26.9% active vs 25.7% passive; odds ratio, 0.96; 95% CI, 0.63-1.45; p = 0.84). Despite a significant increase in rates of successful targeted temperature management, survival to hospital discharge was unchanged. CONCLUSION: Simple quality improvement interventions significantly increased the rates of achieving successful targeted temperature management following out-of-hospital cardiac arrest in a large network of hospitals but did not improve clinical outcomes.

The association between chest compression release velocity and outcomes from out-of-hospital cardiac arrest.

BACKGROUND: Previous studies have demonstrated significant relationships between cardiopulmonary resuscitation (CPR) quality metrics and survival to hospital discharge from out-of-hospital cardiac arrest (OHCA). Recently, it has been suggested that a new metric, chest compression release velocity (CCRV), may be associated with improved survival from OHCA. METHODS AND RESULTS: We performed a retrospective review of all treated adult OHCA occurring over a two year period beginning January 1, 2012. CPR metrics were abstracted from accelerometer measurements during each resuscitation. Multivariable regression analysis was used to examine the impact of CCRV on survival to hospital discharge. Secondary outcome measures were the impact of CCRV on return of spontaneous circulation (ROSC) and neurologically intact survival (MRS ≤ 3). Among 1800 treated OHCA, 1137 met inclusion criteria. The median (IQR) age was 71.6 (60.6, 82.3) with 724 (64%) being male. The median (IQR) CCRV (mm/s) amongst 96 survivors was 334.5 (300.0, 383.2) compared to 304.0 (262.6, 354.1) in 1041 non survivors (p < 0.001). When adjusted for Utstein variables, the odds of survival to hospital discharge for each 10 mm/s increase in CCRV was 1.02 (95% CI: 0.98, 1.06). Similarly the odds of ROSC and neurologically intact survival were 1.01 (95% CI: 0.99, 1.03) and 1.02 (95% CI: 0.98, 1.06), respectively. CONCLUSIONS: When adjusted for Utstein variables, CCRV was not significantly associated with outcomes from OHCA. Further research in other EMS systems is required to clarify the potential impact of this variable on OHCA survival.

Compressions during defibrillator charging shortens shock pause duration and improves chest compression fraction during shockable out of hospital cardiac arrest.

BACKGROUND: Previous studies have demonstrated significant relationships between shock pause duration and survival to hospital discharge from shockable out-of hospital (OHCA) cardiac arrest. Compressions during defibrillator charging (CDC) has been proposed as a technique to shorten shock pause duration. OBJECTIVE: We sought to determine the impact of CDC on shock pause duration and CPR quality measures in shockable OHCA. METHODS: We performed a retrospective review of all treated adult OHCA occurring over a 1 year period beginning August 1, 2011 after training EMS agencies in CDC. We included OHCA patients with an initial shockable rhythm, available CPR process data and shock pause data for up to the first three shocks of the resuscitation. CDC by EMS personnel was confirmed by review of impedance channel measures. We evaluated the relationship between CDC and shock pause duration as the primary outcome measure. Secondary outcome measures investigated the association between CDC and CPR quality measures. RESULTS: Among 747 treated OHCA 149 (23.4%) presented in a shockable rhythm of which 129 (81.6%) met study inclusion criteria. Seventy (54.2%) received CDC. There was no significant difference between the CDC and no CDC group with respect to Utstein variables. Median pre-shock pause (15.0 vs. 3.5s; Δ 11.5; 95% CI: 6.81, 16.19), post-shock pause (4.0 vs. 3.0s; Δ 1.0; 95% CI: -2.57, 4.57), and peri-shock pause (21.0 vs. 9.0s; Δ 12.0; 95% CI: 5.03, 18.97) were all lower for those who received CDC. Mean chest compression fraction was significantly greater (0.77 vs. 0.70, Δ 0.07; 95% CI: 0.03, 0.11) with CDC. No significant difference was noted in compression rate or depth with CDC. Clinical outcomes did not differ between the two approaches (return of spontaneous circulation 62.7% vs. 62.9% p=0.98, survival 25.4% vs. 27.1% p=0.82), although the study was not powered to detect clinical outcome differences. CONCLUSIONS: Compressions during defibrillator charging may shorten shock pause duration and improves chest compression fraction in shockable OHCA. Given the impact on shock pause duration, further study with a larger sample size is required to determine the impact of this technique on clinical outcomes from shockable OHCA.

Implementation trial of the basic life support termination of resuscitation rule: reducing the transport of futile out-of-hospital cardiac arrests.

BACKGROUND: The basic life support (BLS) termination of resuscitation (TOR) rule recommends transport and continued resuscitation when cardiac arrest is witnessed by EMT-Ds, or there is a return of spontaneous circulation, or a shock is given, and prior studies have suggested the transport rate should fall to 37%. METHODS AND RESULTS: This real-time prospective multi-center implementation trial evaluated the BLS TOR rule for compliance, transport rate and provider and physician comfort. Both provider and physician noted their decision-making rationale and ranked their comfort on a 5-point Likert scale. Functional survival was measured at discharge. Of 2421 cardiac arrests, 953 patients were eligible for the rule, which was applied correctly for 755 patients (79%) of which 388 were terminated. 565 patients were transported resulting in a reduction of the transport rate from 100% (historical control) to 59% (p<0.001). The BLS TOR rule was not followed in 198 eligible patients (21%) and they were all transported despite meeting the criteria to terminate. Providers cited 241 reasons for non-compliance: family distress, short transport time interval, younger age and public venue. All 198 transported patients, non-compliant with the rule, died. Both providers and physicians were comfortable with using the rule to guide TOR (median [IQR] of 5 [4,5]; p<0.001). CONCLUSIONS: This implementation trial confirmed the accuracy of the BLS TOR rule in identifying futile out-of-hospital cardiac arrest (OHCA) resuscitations, significantly reduced the transport rate of futile OHCA and most providers and physicians were comfortable following the rule's recommendations.

Validation of a universal prehospital termination of resuscitation clinical prediction rule for advanced and basic life support providers.

BACKGROUND: Prehospital termination of resuscitation rules have been derived for Emergency Medical Technician-Paramedics providing advanced life support care and defibrillation-only Emergency Medical Technicians providing basic life support care. We sought to externally validate each rule on a prospective cohort of prehospital cardiac arrest patients to determine if either rule could be proposed as a universal prehospital termination of resuscitation rule. METHODS: Investigators at the University of Toronto performed a secondary cohort analysis of data prospectively collected for the Resuscitation Outcomes Consortium Epistry-Cardiac Arrest trial from 1 April 2006 to 1 April 2007 by one site. The diagnostic test characteristics and predicted transportation rate were calculated for each rule. RESULTS: Of the 2415 patients with cardiac arrest of presumed cardiac etiology, the advanced life support rule recommended termination of resuscitation for 743 patients. No survivors were identified in this group. It had a specificity of 100% for recommending transport of potential survivors, a positive predictive value of 100% for death and a predicted transport rate of 69%. The basic life support rule recommended termination of resuscitation for 1302 patients, with no survivors. This rule had a specificity of 100%, a positive predictive value of 100% and a predicted transport rate of 46%. CONCLUSIONS: Implementing the basic life support rule as a universal termination of resuscitation clinical prediction rule would result in a lower overall transport rate without missing any potential survivors. The universal rule would recommend termination of resuscitation when there was no return of spontaneous circulation prior to transport, no shock was given and the arrest was not witnessed by Emergency Medical Services personnel. This rule may be useful for emergency medical services systems with mixed levels of providers responding to cardiac arrest patients.