Robert H. Schmicker

Perishock Pause An Independent Predictor of Survival From Out-of-Hospital Shockable Cardiac Arrest

Background— Perishock pauses are pauses in chest compressions before and after defibrillatory shock. We examined the relationship between perishock pauses and survival to hospital discharge. Methods and Results— We included out-of-hospital cardiac arrest patients in the Resuscitation Outcomes Consortium Epistry–Cardiac Arrest who suffered arrest between December 2005 and June 2007, presented with a shockable rhythm (ventricular fibrillation or pulseless ventricular tachycardia), and had cardiopulmonary resuscitation process data for at least 1 shock (n=815). We used multivariable logistic regression to determine the association between survival and perishock pauses. In an analysis adjusted for Utstein predictors of survival, the odds of survival were significantly lower for patients with preshock pause ≥20 seconds (odds ratio, 0.47; 95% confidence interval, 0.27 to 0.82) and perishock pause ≥40 seconds (odds ratio, 0.54; 95% confidence interval, 0.31 to 0.97) compared with patients with preshock pause <10 seconds and perishock pause <20 seconds. Postshock pause was not independently associated with a significant change in the odds of survival. Log-linear modeling depicted a decrease in survival to hospital discharge of 18% and 14% for every 5-second increase in both preshock and perishock pause interval (up to 40 and 50 seconds, respectively), with no significant association noted with changes in the postshock pause interval. Conclusions— In patients with cardiac arrest presenting in a shockable rhythm, longer perishock and preshock pauses were independently associated with a decrease in survival to hospital discharge. The impact of preshock pause on survival suggests that refinement of automatic defibrillator software and paramedic education to minimize preshock pause delays may have a significant impact on survival. # Clinical Perspective {#article-title-32}Background— Perishock pauses are pauses in chest compressions before and after defibrillatory shock. We examined the relationship between perishock pauses and survival to hospital discharge. Methods and Results— We included out-of-hospital cardiac arrest patients in the Resuscitation Outcomes Consortium Epistry–Cardiac Arrest who suffered arrest between December 2005 and June 2007, presented with a shockable rhythm (ventricular fibrillation or pulseless ventricular tachycardia), and had cardiopulmonary resuscitation process data for at least 1 shock (n=815). We used multivariable logistic regression to determine the association between survival and perishock pauses. In an analysis adjusted for Utstein predictors of survival, the odds of survival were significantly lower for patients with preshock pause ≥20 seconds (odds ratio, 0.47; 95% confidence interval, 0.27 to 0.82) and perishock pause ≥40 seconds (odds ratio, 0.54; 95% confidence interval, 0.31 to 0.97) compared with patients with preshock pause <10 seconds and perishock pause <20 seconds. Postshock pause was not independently associated with a significant change in the odds of survival. Log-linear modeling depicted a decrease in survival to hospital discharge of 18% and 14% for every 5-second increase in both preshock and perishock pause interval (up to 40 and 50 seconds, respectively), with no significant association noted with changes in the postshock pause interval. Conclusions— In patients with cardiac arrest presenting in a shockable rhythm, longer perishock and preshock pauses were independently associated with a decrease in survival to hospital discharge. The impact of preshock pause on survival suggests that refinement of automatic defibrillator software and paramedic education to minimize preshock pause delays may have a significant impact on survival.

Early versus Later Rhythm Analysis in Patients with Out-of-Hospital Cardiac Arrest

BACKGROUND In a departure from the previous strategy of immediate defibrillation, the 2005 resuscitation guidelines from the American Heart Association-International Liaison Committee on Resuscitation suggested that emergency medical service (EMS) personnel could provide 2 minutes of cardiopulmonary resuscitation (CPR) before the first analysis of cardiac rhythm. We compared the strategy of a brief period of CPR with early analysis of rhythm with the strategy of a longer period of CPR with delayed analysis of rhythm. METHODS We conducted a cluster-randomized trial involving adults with out-of-hospital cardiac arrest at 10 Resuscitation Outcomes Consortium sites in the United States and Canada. Patients in the early-analysis group were assigned to receive 30 to 60 seconds of EMS-administered CPR and those in the later-analysis group were assigned to receive 180 seconds of CPR, before the initial electrocardiographic analysis. The primary outcome was survival to hospital discharge with satisfactory functional status (a modified Rankin scale score of ≤3, on a scale of 0 to 6, with higher scores indicating greater disability). RESULTS We included 9933 patients, of whom 5290 were assigned to early analysis of cardiac rhythm and 4643 to later analysis. A total of 273 patients (5.9%) in the later-analysis group and 310 patients (5.9%) in the early-analysis group met the criteria for the primary outcome, with a cluster-adjusted difference of -0.2 percentage points (95% confidence interval, -1.1 to 0.7; P=0.59). Analyses of the data with adjustment for confounding factors, as well as subgroup analyses, also showed no survival benefit for either study group. CONCLUSIONS Among patients who had an out-of-hospital cardiac arrest, we found no difference in the outcomes with a brief period, as compared with a longer period, of EMS-administered CPR before the first analysis of cardiac rhythm. (Funded by the National Heart, Lung, and Blood Institute and others; ROC PRIMED ClinicalTrials.gov number, NCT00394706.).

Out-of-hospital cardiac arrest survival improving over time: Results from the Resuscitation Outcomes Consortium (ROC).

BACKGROUND Out-of-hospital cardiac arrest (OHCA) remains a leading cause of death and a 2010 meta-analysis concluded that outcomes have not improved over several decades. However, guidelines have changed to emphasize CPR quality, minimization of interruptions, and standardized post-resuscitation care. We sought to evaluate whether OHCA outcomes have improved over time among agencies participating in the Resuscitation Outcomes Consortium (ROC) cardiac arrest registry (Epistry) and randomized clinical trials (RCTs). METHODS Observational cohort study of 47,148 EMS-treated OHCA cases in Epistry from 139 EMS agencies at 10 ROC sites that participated in at least one RCT between 1/1/2006 and 12/31/2010. We reviewed patient, scene, event characteristics, and outcomes of EMS-treated OHCA over time, including subgroups with initial rhythm of pulseless ventricular tachycardia or ventricular fibrillation (VT/VF). RESULTS Mean response interval, median age and male proportion remained similar over time. Unadjusted survival to discharge increased between 2006 and 2010 for treated OHCA (from 8.2% to 10.4%), as well as for subgroups of VT/VF (21.4% to 29.3%) and bystander witnessed VT/VF (23.5% to 30.3%). Compared with 2006, adjusted survival to discharge was significantly higher in 2010 for treated cases (OR = 1.72; 95% CI 1.53, 1.94), VT/VF cases (OR = 1.69; 95% CI 1.45, 1.98) and bystander witnessed VT/VF cases (OR = 1.65; 95% CI 1.36, 2.00). Tests for trend in each subgroup were significant (p < 0.001). CONCLUSIONS ROC-wide survival increased significantly between 2006 and 2010. Additional research efforts are warranted to identify specific factors associated with this improvement.

Receiving Hospital Characteristics Associated with Survival after Out-of-Hospital Cardiac Arrest

AIM Survival after out-of-hospital cardiac arrest (OOHCA) varies between regions, but the contribution of different factors to this variability is unknown. This study examined whether survival to hospital discharge was related to receiving hospital characteristics, including bed number, capability of performing cardiac catheterization and hospital volume of OOHCA cases. MATERIAL AND METHODS Prospective observational database of non-traumatic OOHCA assessed by emergency medical services was created in 8 US and 2 Canadian sites from December 1, 2005 to July 1, 2007. Subjects received hospital care after OOHCA, defined as either (1) arriving at hospital with pulses, or (2) arriving at hospital without pulses, but discharged or died > or =1 day later. RESULTS A total of 4087 OOHCA subjects were treated at 254 hospitals, and 32% survived to hospital discharge. A majority of subjects (68%) were treated at 116 (46%) hospitals capable of cardiac catheterization. Unadjusted survival to discharge was greater in hospitals performing cardiac catheterization (34% vs. 27%, p=0.001), and in hospitals that received > or =40 patients/year compared to those that received <40 (37% vs. 30%, p=0.01). Survival was not associated with hospital bed number, teaching status or trauma center designation. Length of stay (LOS) for surviving subjects was shorter at hospitals performing cardiac catheterization (p<0.01). After adjusting for all variables, there were no independent associations between survival or LOS and hospital characteristics. CONCLUSIONS Some subsets of hospitals displayed higher survival and shorter LOS for OOHCA subjects but there was no independent association between hospital characteristics and outcome.

Early coronary angiography and induced hypothermia are associated with survival and functional recovery after out-of-hospital cardiac arrest

BACKGROUND The rate and effect of coronary interventions and induced hypothermia after out-of-hospital cardiac arrest (OHCA) are unknown. We measured the association of early (≤24h after arrival) coronary angiography, reperfusion, and induced hypothermia with favorable outcome after OHCA. METHODS We performed a secondary analysis of a multicenter clinical trial (NCT00394706) conducted between 2007 and 2009 in 10 North American regions. Subjects were adults (≥18 years) hospitalized after OHCA with pulses sustained ≥60min. We measured the association of early coronary catheterization, percutaneous coronary intervention, fibrinolysis, and induced hypothermia with survival to hospital discharge with favorable functional status (modified Rankin Score≤3). RESULTS From 16,875 OHCA subjects, 3981 (23.6%) arrived at 151 hospitals with sustained pulses. 1317 (33.1%) survived to hospital discharge, with 1006 (25.3%) favorable outcomes. Rates of early coronary catheterization (19.2%), coronary reperfusion (17.7%) or induced hypothermia (39.3%) varied among hospitals, and were higher in hospitals treating more subjects per year. Odds of survival and favorable outcome increased with hospital volume (per 5 subjects/year OR 1.06; 95%CI: 1.04-1.08 and OR 1.06; 95%CI: 1.04, 1.08, respectively). Survival and favorable outcome were independently associated with early coronary angiography (OR 1.69; 95%CI 1.06-2.70 and OR 1.87; 95%CI 1.15-3.04), coronary reperfusion (OR 1.94; 95%CI 1.34-2.82 and OR 2.14; 95%CI 1.46-3.14), and induced hypothermia (OR 1.36; 95%CI 1.01-1.83 and OR 1.42; 95%CI 1.04-1.94). INTERPRETATION Early coronary intervention and induced hypothermia are associated with favorable outcome and are more frequent in hospitals that treat higher numbers of OHCA subjects per year.

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.).

The impact of peri-shock pause on survival from out-of-hospital shockable cardiac arrest during the Resuscitation Outcomes Consortium PRIMED trial.

BACKGROUND Previous research has demonstrated significant relationships between peri-shock pause and survival to discharge from out-of-hospital shockable cardiac arrest (OHCA). OBJECTIVE To determine the impact of peri-shock pause on survival from OHCA during the ROC PRIMED randomized controlled trial. METHODS We included patients in the ROC PRIMED trial who suffered OHCA between June 2007 and November 2009, presented with a shockable rhythm and had CPR process data for at least one shock. We used multivariable logistic regression to determine the association between peri-shock pause duration and survival to hospital discharge. RESULTS Among 2006 patients studied, the median (IQR) shock pause duration was: pre-shock pause 15s (8, 22); post-shock pause 6s (4, 9); and peri-shock pause 22.0 s (14, 31). After adjusting for Utstein predictors of survival as well as CPR quality measures, the odds of survival to hospital discharge were significantly higher for patients with pre-shock pause <10s (OR: 1.52, 95% CI: 1.09, 2.11) and peri-shock pause <20s (OR: 1.82, 95% CI: 1.17, 2.85) when compared to patients with pre-shock pause ≥ 20s and peri-shock pause ≥ 40s. Post-shock pause was not significantly associated with survival to hospital discharge. Results for neurologically intact survival (Modified Rankin Score ≤ 3) were similar to our primary outcome. CONCLUSIONS In patients with cardiac arrest presenting in a shockable rhythm during the ROC PRIMED trial, shorter pre- and peri-shock pauses were significantly associated with higher odds of survival. Future cardiopulmonary education and technology should focus on minimizing all peri-shock pauses.

Out-of-Hospital Cardiac Arrest Frequency and Survival: Evidence for Temporal Variability

AIM Some cardiac phenomena demonstrate temporal variability. We evaluated temporal variability in out-of-hospital cardiac arrest (OHCA) frequency and outcome. METHODS Prospective cohort study (the Resuscitation Outcomes Consortium) of all OHCA of presumed cardiac cause who were treated by emergency medical services within 9 US and Canadian sites between 12/1/2005 and 02/28/2007. In each site, Emergency Medical System records were collected and analyzed. Outcomes were individually verified by trained data abstractors. RESULTS There were 9667 included patients. Median age was 68 (IQR 24) years, 66.7% were male and 8.3% survived to hospital discharge. The frequency of cardiac arrest varied significantly across time blocks (p<0.001). Compared to the 0001-0600 hourly time block, the odds ratios and 95% CIs for the occurrence of OHCA were 2.02 (1.90, 2.15) in the 0601-1200 block, 2.01 (1.89, 2.15) in the 1201-1800 block, and 1.73 (1.62, 1.85) in the 1801-2400 block. The frequency of all OHCA varied significantly by day of week (p=0.03) and month of year (p<0.001) with the highest frequencies on Saturday and during December. Survival to hospital discharge was lowest when the OHCA occurred during the 0001-0600 time block (7.3%) and highest during the 1201-1800 time block (9.6%). Survival was highest for OHCAs occurring on Mondays (10.0%) and lowest for those on Wednesdays (6.8%) (p=0.02). CONCLUSION There is temporal variability in OHCA frequency and outcome. Underlying patient, EMS system and environmental factors need to be explored to offer further insight into these observed patterns.

Socioeconomic status and incidence of sudden cardiac arrest

Background: Low socioeconomic status is associated with poor cardiovascular health. We evaluated the association between socioeconomic status and the incidence of sudden cardiac arrest, a condition that accounts for a substantial proportion of cardiovascular-related deaths, in seven large North American urban populations. Methods: Using a population-based registry, we collected data on out-of-hospital sudden cardiac arrests occurring at home or at a residential institution from Apr. 1, 2006, to Mar. 31, 2007. We limited the analysis to cardiac arrests in seven metropolitan areas in the United States (Dallas, Texas; Pittsburgh, Pennsylvania; Portland, Oregon; and Seattle–King County, Washington) and Canada (Ottawa and Toronto, Ontario; and Vancouver, British Columbia). Each incident was linked to a census tract; tracts were classified into quartiles of median household income. Results: A total of 9235 sudden cardiac arrests were included in the analysis. For all sites combined, the incidence of sudden cardiac arrestin the lowest socioeconomic quartile was nearly double that in the highest quartile (incidence rate ratio [IRR] 1.9, 95% confidence interval [CI] 1.8–2.0). This disparity was greater among people less than 65 years old (IRR 2.7, 95% CI 2.5–3.0) than among those 65 or older (IRR 1.3, 95% CI 1.2–1.4). After adjustment for study site and for population age structure of each census tract, the disparity across socioeconomic quartiles for all ages combined was greater in the United States (IRR 2.0, 95% CI 1.9–2.2) than in Canada (IRR 1.8, 95% CI 1.6–2.0) (p < 0.001 for interaction). Interpretation: The incidence of sudden cardiac arrest at home or at a residential institution was higher in poorer neighbourhoods of the US and Canadian sites studied, although the association was attenuated in Canada. The disparity across socioeconomic quartiles was greatest among people younger than 65. The association between socioeconomic status and incidence of sudden cardiac arrest merits consideration in the development of strategies to improve survival from sudden cardiac arrest, and possibly to identify opportunities for prevention.

Detailed description of all deaths in both the shock and traumatic brain injury hypertonic saline trials of the Resuscitation Outcomes Consortium

OBJECTIVE To identify causes and timing of mortality in trauma patients to determine targets for future studies. BACKGROUND In trials conducted by the Resuscitation Outcomes Consortium in patients with traumatic hypovolemic shock (shock) or traumatic brain injury (TBI), hypertonic saline failed to improve survival. Selecting appropriate candidates is challenging. METHODS Retrospective review of patients enrolled in multicenter, randomized trials performed from 2006 to 2009. Inclusion criteria were as follows: injured patients, age 15 years or more with hypovolemic shock [systolic blood pressure (SBP) ≤ 70 mm Hg or SBP 71-90 mm Hg with heart rate ≥ 108) or severe TBI [Glasgow Coma Score (GCS) ≤ 8]. Initial fluid administered was 250 mL of either 7.5% saline with 6% dextran 70, 7.5% saline or 0.9% saline. RESULTS A total of 2061 subjects were enrolled (809 shock, 1252 TBI) and 571 (27.7%) died. Survivors were younger than nonsurvivors [30 (interquartile range 23) vs 42 (34)] and had a higher GCS, though similar hemodynamics. Most deaths occurred despite ongoing resuscitation. Forty-six percent of deaths in the TBI cohort were within 24 hours, compared with 82% in the shock cohort and 72% in the cohort with both shock and TBI. Median time to death was 29 hours in the TBI cohort, 2 hours in the shock cohort, and 4 hours in patients with both. Sepsis and multiple organ dysfunction accounted for 2% of deaths. CONCLUSIONS Most deaths from trauma with shock or TBI occur within 24 hours from hypovolemic shock or TBI. Novel resuscitation strategies should focus on early deaths, though prevention may have a greater impact.