Lower-dose epinephrine administration and out-of-hospital cardiac arrest outcomes.

BACKGROUND: International guidelines recommend administration of 1 mg of intravenous epinephrine every 3-5 min during cardiac arrest. The optimal dose of epinephrine is not known. We evaluated the association of reduced frequency and dose of epinephrine with survival after out-of-hospital cardiac arrest (OHCA). METHODS: Included were patients with non-traumatic OHCA treated by advanced life support (ALS) providers from January 1, 2008 to June 30, 2016. During the before period, providers were instructed to give epinephrine 1 mg intravenously at 4 min followed by additional 1 mg doses every eight minutes to patients with OHCA with a shockable rhythm and 1 mg doses every two minutes to patients with a non-shockable rhythm (higher dose). On October 1, 2012, providers were instructed to reduce the dose of epinephrine treatment during out-of-hospital cardiac arrest (OHCA): 0.5 mg at 4 and 8 min followed by additional doses of 0.5 mg every 8 min for shockable rhythms and 0.5 mg every 2 min for non-shockable rhythms (lower dose). Patients with shockable initial rhythms were analyzed separately from those with non-shockable initial rhythms. The primary outcome was survival to hospital discharge with a secondary outcome of favorable neurological status (Cerebral Performance Category [CPC] 1 or 2) at hospital discharge. Multiple logistic regression modeling was used to adjust for age, sex, presence of a witness, bystander CPR, and response interval. RESULTS: 2255 patients with OHCA were eligible for analysis. Of these, 24.6% had an initially shockable rhythm. Total epinephrine dose per patient decreased from a mean ±â€¯standard deviation of 3.4 ±â€¯2.3 mg-2.6 ±â€¯1.9 mg (p < 0.001) in the shockable group and 3.5 ±â€¯1.9 mg-2.8 ±â€¯1.7 mg (p < 0.001) in the non-shockable group. Among those with a shockable rhythm, survival to hospital discharge was 35.0% in the higher dose group vs. 34.2% in the lower dose group. Among those with a non-shockable rhythm, survival was 4.2% in the higher dose group vs. 5.1% in the lower dose group. Lower dose vs. higher dose was not significantly associated with survival: adjusted odds ratio, aOR 0.91 (95% CI 0.62-1.32, p = 0.61) if shockable and aOR 1.26 (95% CI 0.79-2.01, p = 0.33) if non-shockable. Lower dose vs. higher dose was not significantly associated with favorable neurological status at discharge: aOR 0.84 (95% CI 0.57-1.24, p = 0.377) if shockable and aOR 1.17 (95% CI 0.68-2.02, p = 0.577) if non-shockable. CONCLUSION: Reducing the dose of epinephrine administered during out-of-hospital cardiac arrest was not associated with a change in survival to hospital discharge or favorable neurological outcomes after OHCA.

The impact of first responder turnout and curb-to-care intervals on survival from out-of-hospital cardiac arrest.

PURPOSE: Patients with out-of-hospital cardiac arrest (OHCA) more likely survive when emergency medical services (EMS) arrive quickly. We studied time response elements in OHCA with attention to EMS intervals before wheels roll and after wheels stop to understand their contribution to total time response and clinical outcome. METHODS: We analyzed EMS responses to OHCA from 2009-2014 in an urban, fire department based system. The Call-to-Care Interval, from call receipt to hands-on EMS care, was comprised of four time intervals: 1) call received to EMS notification (Activation), 2) EMS notification to vehicle wheels rolling (Turnout), 3) wheels rolling to arrival at scene (Travel), and 4) arrival at scene to hands-on EMS care (Curb-to-Care). We created a new time interval (On-Feet) comprised of the turnout and curb-to-care intervals. Using logistic regression, we evaluated whether the total EMS response interval and discrete time intervals were related to survival to discharge. RESULTS: Of 1,831 cases, 1,806 (98.6%) had complete information. The mean lengths for the intervals were 7.2±3.6min. (call-to-care), 58±39s (activation), 63±29s (turnout), 2.5±1.3min (travel), 2.4±1.6min (curb-to-care), and 3.5±1.7min (on-feet). After adjustment, "On Feet" interval was associated with OHCA survival (OR=0.91 [95% CI=0.83-1.00] for each additional minute). CONCLUSIONS: Turnout and curb-to-care intervals were half of the total response interval in our EMS system. Measurement should incorporate these two intervals to accurately characterize and possibly reduce the professional response interval.

Briefer activation time is associated with better outcomes after out-of-hospital cardiac arrest.

BACKGROUND: Treatment of out-of-hospital cardiac arrest (OHCA) requires prompt intervention. Better outcomes are associated with briefer time from dispatch of emergency medical services (EMS) providers to arrival on scene, application of a defibrillator or insertion of an advanced airway. We assessed whether time from receipt of a call by a telecommunicator to dispatch of EMS providers was associated with outcomes. METHODS: This was a retrospective analysis of a prospective cohort study of persons who had OHCA treated by EMS providers in Seattle, WA. Activation interval was defined as time from call pick up by telecommunicator to notification of EMS providers to respond to the call. Response interval was defined as the time from notification of EMS providers to their arrival at patient side. We determined the association between time intervals and outcomes of sustained restoration of spontaneous circulation (ROSC), survival to hospital discharge and neurologically favorable survival using multiple logistic regression. Secondary analyses assessed the relative contribution of activation versus response interval, and adjusted for post-treatment patient and EMS characteristics. RESULTS: Among 2,687 patients, activation interval was mean 1.2±0.6min. Response interval was mean 6.1±2.4min. 1,232 (45.9%) achieved ROSC; 475 (17.7%) survived to discharge; and 428 (15.9%) had favorable neurologic status at discharge. Compared to an activation interval of at least 1.5min, patients with briefer intervals were more likely to survive to discharge (adjusted odds ratio (OR) for <1min, 1.69 (95% confidence interval (CI), 1.26, 2.28); adjusted odds ratio for 1 to 1.49min, 1.54 (95% CI, 1.14, 2.08); p value=0.002). With baseline survival of 10%, the absolute increase in survival associated with a 30s decrease in activation interval was 0.7% and for a 30s decrease in response interval was 0.4%. CONCLUSIONS: Briefer activation interval was independently associated with greater survival. Further research is needed to assess whether reduction of the activation interval improves outcome after OHCA.

Effect of prehospital induction of mild hypothermia on 3-month neurological status and 1-year survival among adults with cardiac arrest: long-term follow-up of a randomized, clinical trial.

BACKGROUND: Randomized trials of prehospital cooling after cardiac arrest have shown that neither prehospital cooling nor targeted temperature management differentially affected short-term survival or neurological function. In this follow-up study, we assess the association of prehospital hypothermia with neurological function at least 3 months after cardiac arrest and survival 1 year after cardiac arrest. METHODS AND RESULTS: There were 508 individuals who were discharged alive from hospitals in King County, Washington; 373 (73%) were interviewed by telephone 123±43 days after the initial event. Overall, 59% of the treatment group and 58% of the control group had Cerebral Performance Category (CPC) 1 or 2 (P=0.70), and 50% of the treatment group and 49% of the control group had slight disability or better by the Modified Rankin Scale (MRS; (P=0.35). One-year survival was 87% in the treatment group and 84% in the control group (P=0.42). Of those with CPC 1 at hospital discharge, 68% had CPC 1 or 2 at follow-up, and 59% had MRS of slight disability or better. Of 41 patients with CPC 3 or 4 at discharge, only 12% had CPC 2 at follow-up, and just 5% had MRS of slight disability or better. One-year survival was 92% for CPC 1 at discharge, but only 40% for CPC 4. CONCLUSION: In addition to excellent survival, patients who had good neurological function at discharge continued to have good function at least 3 months after the event. CLINICAL TRIAL REGISTRATION: URL: Clinicaltrials.gov. Unique identifier: NCT00391469.

Erythrocyte very long-chain saturated fatty acids associated with lower risk of incident sudden cardiac arrest.

Prior studies suggest that circulating n-3 and trans-fatty acids influence the risk of sudden cardiac arrest (SCA). Yet, while other fatty acids also differ in their membrane properties and biological activities which may influence SCA, little is known about the associations of other circulating fatty acids with SCA. The aim of this study was to investigate the associations of 17 erythrocyte membrane fatty acids with SCA risk. We used data from a population-based case-control study of SCA in the greater Seattle, Washington, area. Cases, aged 25-74 years, were out-of-hospital SCA patients, attended by paramedics (n=265). Controls, matched to cases by age, sex and calendar year, were randomly identified from the community (n=415). All participants were free of prior clinically-diagnosed heart disease. Blood was obtained at the time of cardiac arrest by attending paramedics (cases) or at the time of an interview (controls). Higher levels of erythrocyte very long-chain saturated fatty acids (VLSFA) were associated with lower risk of SCA. After adjustment for risk factors and levels of n-3 and trans-fatty acids, higher levels of 20:0 corresponding to 1 SD were associated with 30% lower SCA risk (13-43%, p=0.001). Higher levels of 22:0 and 24:0 were associated with similar lower SCA risk (ORs for 1 SD-difference: 0.71 [95% CI: 0.57-0.88, p=0.002] for 22:0; and 0.79 [95% CI: 0.63-0.98, p=0.04] for 24:0). These novel findings support the need for investigation of biologic effects of circulating VLSFA and their determinants.

Effect of prehospital induction of mild hypothermia on survival and neurological status among adults with cardiac arrest: a randomized clinical trial.

IMPORTANCE: Hospital cooling improves outcome after cardiac arrest, but prehospital cooling immediately after return of spontaneous circulation may result in better outcomes. OBJECTIVE: To determine whether prehospital cooling improves outcomes after resuscitation from cardiac arrest in patients with ventricular fibrillation (VF) and without VF. DESIGN, SETTING, AND PARTICIPANTS: A randomized clinical trial that assigned adults with prehospital cardiac arrest to standard care with or without prehospital cooling, accomplished by infusing up to 2 L of 4°C normal saline as soon as possible following return of spontaneous circulation. Adults in King County, Washington, with prehospital cardiac arrest and resuscitated by paramedics were eligible and 1359 patients (583 with VF and 776 without VF) were randomized between December 15, 2007, and December 7, 2012. Patient follow-up was completed by May 1, 2013. Nearly all of the patients resuscitated from VF and admitted to the hospital received hospital cooling regardless of their randomization. MAIN OUTCOMES AND MEASURES: The primary outcomes were survival to hospital discharge and neurological status at discharge. RESULTS: The intervention decreased mean core temperature by 1.20°C (95% CI, -1.33°C to -1.07°C) in patients with VF and by 1.30°C (95% CI, -1.40°C to -1.20°C) in patients without VF by hospital arrival and reduced the time to achieve a temperature of less than 34°C by about 1 hour compared with the control group. However, survival to hospital discharge was similar among the intervention and control groups among patients with VF (62.7% [95% CI, 57.0%-68.0%] vs 64.3% [95% CI, 58.6%-69.5%], respectively; P = .69) and among patients without VF (19.2% [95% CI, 15.6%-23.4%] vs 16.3% [95% CI, 12.9%-20.4%], respectively; P = .30). The intervention was also not associated with improved neurological status of full recovery or mild impairment at discharge for either patients with VF (57.5% [95% CI, 51.8%-63.1%] of cases had full recovery or mild impairment vs 61.9% [95% CI, 56.2%-67.2%] of controls; P = .69) or those without VF (14.4% [95% CI, 11.3%-18.2%] of cases vs 13.4% [95% CI,10.4%-17.2%] of controls; P = .30). Overall, the intervention group experienced rearrest in the field more than the control group (26% [95% CI, 22%-29%] vs 21% [95% CI, 18%-24%], respectively; P = .008), as well as increased diuretic use and pulmonary edema on first chest x-ray, which resolved within 24 hours after admission. CONCLUSION AND RELEVANCE: Although use of prehospital cooling reduced core temperature by hospital arrival and reduced the time to reach a temperature of 34°C, it did not improve survival or neurological status among patients resuscitated from prehospital VF or those without VF. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00391469.

Cardiac arrest at exercise facilities: implications for placement of automated external defibrillators.

OBJECTIVES: This study sought to characterize the relative frequency, care, and survival of sudden cardiac arrest in traditional indoor exercise facilities, alternative indoor exercise sites, and other indoor sites. BACKGROUND: Little is known about the relative frequency of sudden cardiac arrest at traditional indoor exercise facilities versus other indoor locations where people engage in exercise or about the survival at these sites in comparison with other indoor locations. METHODS: We examined every public indoor sudden cardiac arrest in Seattle and King County from 1996 to 2008 and categorized each event as occurring at a traditional exercise center, an alternative exercise site, or a public indoor location not used for exercise. Arrests were further defined by the classification of the site, activity performed, demographics, characteristics of treatment, and survival. For some location types, annualized site incident rates of cardiac arrests were calculated. RESULTS: We analyzed 849 arrests, with 52 at traditional centers, 84 at alternative exercise sites, and 713 at sites not associated with exercise. The site incident rates of arrests at indoor tennis facilities, indoor ice arenas, and bowling alleys were higher than at traditional fitness centers. Survival to hospital discharge was greater at exercise sites (56% at traditional and 45% at alternative) than at other public indoor locations (34%; p = 0.001). CONCLUSIONS: We observed a higher rate of cardiac arrests at some alternative exercise facilities than at traditional exercise sites. Survival was higher at exercise sites than at nonexercise indoor sites. These data have important implications for automated external defibrillator placement.

Study design for the Immediate Myocardial Metabolic Enhancement During Initial Assessment and Treatment in Emergency Care (IMMEDIATE) Trial: A double-blind randomized controlled trial of intravenous glucose, insulin, and potassium for acute coronary syndromes in emergency medical services.

BACKGROUND: Experimental studies suggest that metabolic myocardial support by intravenous (IV) glucose, insulin, and potassium (GIK) reduces ischemia-induced arrhythmias, cardiac arrest, mortality, progression from unstable angina pectoris to acute myocardial infarction (AMI), and myocardial infarction size. However, trials of hospital administration of IV GIK to patients with ST-elevation myocardial infarction (STEMI) have generally not shown favorable effects possibly because of the GIK intervention taking place many hours after ischemic symptom onset. A trial of GIK used in the very first hours of ischemia has been needed, consistent with the timing of benefit seen in experimental studies. OBJECTIVE: The IMMEDIATE Trial tested whether, if given very early, GIK could have the impact seen in experimental studies. Accordingly, distinct from prior trials, IMMEDIATE tested the impact of GIK (1) in patients with acute coronary syndromes (ACS), rather than only AMI or STEMI, and (2) administered in prehospital emergency medical service settings, rather than later, in hospitals, after emergency department evaluation. DESIGN: The IMMEDIATE Trial was an emergency medical service-based randomized placebo-controlled clinical effectiveness trial conducted in 13 cities across the United States that enrolled 911 participants. Eligible were patients 30 years or older for whom a paramedic performed a 12-lead electrocardiogram to evaluate chest pain or other symptoms suggestive of ACS for whom electrocardiograph-based acute cardiac ischemia time-insensitive predictive instrument indicated a ≥75% probability of ACS, and/or the thrombolytic predictive instrument indicated the presence of a STEMI, or if local criteria for STEMI notification of receiving hospitals were met. Prehospital IV GIK or placebo was started immediately. Prespecified were the primary end point of progression of ACS to infarction and, as major secondary end points, the composite of cardiac arrest or in-hospital mortality, 30-day mortality, and the composite of cardiac arrest, 30-day mortality, or hospitalization for heart failure. Analyses were planned on an intent-to-treat basis, on a modified intent-to-treat group who were confirmed in emergency departments to have ACS, and for participants presenting with STEMI. CONCLUSION: The IMMEDIATE Trial tested whether GIK, when administered as early as possible in the course of ACS by paramedics using acute cardiac ischemia time-insensitive predictive instrument and thrombolytic predictive instrument decision support, would reduce progression to AMI, mortality, cardiac arrest, and heart failure. It also tested whether it would provide clinical and pathophysiologic information on GIK's biological mechanisms.

Comparison of role of early (less than six hours) to later (more than six hours) or no cardiac catheterization after resuscitation from out-of-hospital cardiac arrest.

Despite reports of patients with resuscitated sudden cardiac arrest (rSCA) receiving acute cardiac catheterization, the efficacy of this strategy is largely unknown. We hypothesized that acute cardiac catheterization of patients with rSCA would improve survival to hospital discharge. A retrospective cohort of 240 patients with out-of-hospital rSCA caused by ventricular tachycardia or fibrillation was identified from 11 institutions in Seattle, Washington from 1999 through 2002. Patients were grouped into those receiving acute catheterization within 6 hours (≤6-hour group, n = 61) and those with deferred catheterization at >6 hours or no catheterization during the index hospitalization (>6-hour group, n = 179). Attention was directed to survival to hospital discharge, neurologic status, extent of coronary artery disease, presenting electrocardiographic findings, and symptoms before arrest. Propensity-score methods were used to adjust for the likelihood of receiving acute catheterization. Survival was greater in patients who underwent acute catheterization (72% in the ≤6-hour group vs 49% in the >6-hour group, p = 0.001). Percutaneous coronary intervention was performed in 38 of 61 patients (62%) in the ≤6-hour group and 13 of 170 patients (7%) in the >6-hour group (p <0.0001). Neurologic status was similar in the 2 groups. A significantly larger percentage of patients in the acute catheterization group had symptoms before cardiac arrest and had ST-segment elevation on electrocardiogram after resuscitation. Age, bystander cardiopulmonary resuscitation, daytime presentation, history of percutaneous coronary intervention or stroke, and acute ST-segment elevation were positively associated with receiving cardiac catheterization. In conclusion, in this series of patients who sustained out-of-hospital cardiac arrest, acute catheterization (<6 hours of presentation) was associated with improved survival.

Active surface cooling protocol to induce mild therapeutic hypothermia after out-of-hospital cardiac arrest: a retrospective before-and-after comparison in a single hospital.

OBJECTIVE: To evaluate whether implementation of a therapeutic hypothermia protocol on arrival in a community hospital improved survival and neurologic outcomes in patients initially found to have ventricular fibrillation, pulseless electrical activity, or asystole, and then successfully resuscitated from out-of-hospital cardiac arrest. DESIGN: A retrospective study of patients who presented after implementation of a therapeutic hypothermia protocol compared with those who presented before the protocol was implemented. SETTING: Harborview Medical Center, Seattle, WA. PATIENTS: A total of 491 consecutive adults with out-of-hospital, nontraumatic cardiac arrest who presented between January 1, 2000 and December 31, 2004. INTERVENTIONS: An active cooling therapeutic hypothermia protocol, using ice packs, cooling blankets, or cooling pads to achieve a temperature of 32 degrees C to 34 degrees C was initiated on November 18, 2002 for unconscious patients resuscitated from cardiac arrest. MEASUREMENTS AND MAIN RESULTS: Demographics and outcomes were obtained from medical records and an emergency medical database. The primary outcomes were survival and favorable neurologic outcome at discharge associated with the therapeutic hypothermia protocol. An adjusted analysis was performed, using a multivariate regression. During the therapeutic hypothermia period, 204 patients were brought to the emergency department; of these 204 patients, 132 (65%) ultimately achieved temperatures of <34 degrees C. Of the 72 patients who did not achieve goal temperatures: 40 (20%) died in the emergency department or shortly after being admitted to the hospital, 15 (7%) regained consciousness, four (2%) had contraindications, 13 (6%) had temperature increase or did not have documented use of the therapeutic hypothermia protocol. In the prior period, none of the 287 patients received active cooling. Patients admitted in the therapeutic hypothermia period had a mean esophageal temperature of 34.1 degrees C during the first 12 hrs compared with 35.2 degrees C in the pretherapeutic hypothermia period (p < .01). Survival to hospital discharge improved in the therapeutic hypothermia period in patients with an initial rhythm of ventricular fibrillation (odds ratio, 1.88, 95% confidence interval, 1.03-3.45), however not in patients with nonventricular fibrillation (odds ratio, 1.17, 95% confidence interval, 0.66-2.05). In adjusted analysis, ventricular fibrillation patients during the therapeutic hypothermia period trended toward improved survival (odds ratio, 1.71, 95% confidence interval, 0.85-3.46) and had favorable neurologic outcome (odds ratio, 2.62, 95% confidence interval, 1.1-6.27) compared with the earlier period. This benefit was not observed in patients whose initial rhythm was pulseless electrical activity or asystole. CONCLUSIONS: The therapeutic hypothermia period was associated with a significant improvement in neurologic outcomes in patients whose initial rhythm was ventricular fibrillation, but not in patients with other rhythms.

Red blood cell membrane alpha-linolenic acid and the risk of sudden cardiac arrest.

Higher levels of long-chain n-3 polyunsaturated fatty acids in red blood cell membranes are associated with lower risk of sudden cardiac arrest. Whether membrane levels of alpha-linolenic acid, a medium-chain n-3 polyunsaturated fatty acid, show a similar association is unclear. We investigated the association of red blood cell membrane alpha-linolenic acid with sudden cardiac arrest risk in a population-based case-control study. Cases, aged 25 to 74 years, were out-of-hospital sudden cardiac arrest patients attended by paramedics in Seattle, WA (n = 265). Controls, matched to cases by age, sex, and calendar year, were randomly identified from the community (n = 415). All participants were free of prior clinically diagnosed heart disease. Blood was obtained at the time of cardiac arrest (cases) or at the time of an interview (controls). Higher membrane alpha-linolenic acid was associated with a higher risk of sudden cardiac arrest: after adjustment for matching factors and smoking, diabetes, hypertension, education, physical activity, weight, height, and total fat intake, the odds ratios corresponding to increasing quartiles of alpha-linolenic acid were 1.7 (95% confidence interval [CI], 1.0-3.0), 1.9 (95% CI, 1.1-3.3), and 2.5 (95% CI, 1.3-4.8) compared with the lowest quartile. The association was independent of red blood cell levels of long-chain n-3 fatty acids, trans-fatty acids, and linoleic acid. Higher membrane levels of alpha-linolenic acid are associated with higher risk of sudden cardiac arrest.

The use of pre-hospital mild hypothermia after resuscitation from out-of-hospital cardiac arrest.

Hypothermia has emerged as a potent neuroprotective modality following resuscitation from cardiac arrest. Although delayed hospital cooling has been demonstrated to improve outcome after cardiac arrest, in-field cooling begun immediately following the return of spontaneous circulation may be more beneficial. Cooling in the field following resuscitation, however, presents new challenges, in that the cooling method has to be portable, safe, and effective. Rapid infusion of intravenous fluid at 4 degrees C, the use of a cooling helmet, and cooling plates have all been proposed as methods for field cooling, and are all in various stages of clinical and animal testing. Whether field cooling will improve survival and neurologic outcome remains an important unanswered clinical question.

Pilot randomized clinical trial of prehospital induction of mild hypothermia in out-of-hospital cardiac arrest patients with a rapid infusion of 4 degrees C normal saline.

BACKGROUND: Although delayed hospital cooling has been demonstrated to improve outcome after cardiac arrest, in-field cooling started immediately after the return of spontaneous circulation may be more beneficial. The aims of the present pilot study were to assess the feasibility, safety, and effectiveness of in-field cooling. METHODS AND RESULTS: We determined the effect on esophageal temperature, before hospital arrival, of infusing up to 2 L of 4 degrees C normal saline as soon as possible after resuscitation from out-of-hospital cardiac arrest. A total of 125 such patients were randomized to receive standard care with or without intravenous cooling. Of the 63 patients randomized to cooling, 49 (78%) received an infusion of 500 to 2000 mL of 4 degrees C normal saline before hospital arrival. These 63 patients experienced a mean temperature decrease of 1.24+/-1 degrees C with a hospital arrival temperature of 34.7 degrees C, whereas the 62 patients not randomized to cooling experienced a mean temperature increase of 0.10+/-0.94 degrees C (P<0.0001) with a hospital arrival temperature of 35.7 degrees C. In-field cooling was not associated with adverse consequences in terms of blood pressure, heart rate, arterial oxygenation, evidence for pulmonary edema on initial chest x-ray, or rearrest. Secondary end points of awakening and discharged alive from hospital trended toward improvement in ventricular fibrillation patients randomized to in-field cooling. CONCLUSIONS: These pilot data suggest that infusion of up to 2 L of 4 degrees C normal saline in the field is feasible, safe, and effective in lowering temperature. We propose that the effect of this cooling method on neurological outcome after cardiac arrest be studied in larger numbers of patients, especially those whose initial rhythm is ventricular fibrillation.

The relationship between shocks and survival in out-of-hospital cardiac arrest patients initially found in PEA or asystole.

OBJECTIVE: To describe survival rates from out-of-hospital cardiac arrest for patients who present with pulseless electrical activity or asystole according to whether they remained in a non-shockable rhythm or converted to ventricular fibrillation and were shocked appropriately. RESULTS: Observational analysis of a cardiac arrest registry collected as part of a randomized trial. SETTING: Five urban/suburban cities in the United States and Canada. PARTICIPANTS: Trial subjects (adult, treated, non-traumatic) whose first documented heart rhythm/state following cardiac arrest was asystole or pulseless electrical activity. INTERVENTION: Periodic pauses to assess for shockable rhythm. MAIN OUTCOME MEASURE: Survival to hospital discharge. RESULTS: Of 1377 cardiac arrest patients, 738 presented with an initial arrest rhythm/state of either pulseless electrical activity or asystole. Of the 738, 78% (n=574) subsequently remained in a non-shockable rhythm/state at each evaluation throughout the resuscitation (No-Shock group) while 22% (n=164) converted to ventricular fibrillation and were shocked by emergency medical service (Shock group). Survival to hospital discharge was significantly greater in the No-Shock group (4.9% versus 0.6%, p=0.01). Shock group remained a predictor (odds ratios=0.18, p=0.036) of death after adjustment for potential confounders. CONCLUSIONS: These results suggest that patients with cardiac arrest who develop VF during the course of treatment for initially observed pulseless electrical activity or asystole do not benefit from conventional approaches to treatment such as defibrillation. Further study is warranted to define the optimal treatment of this patient cohort.

Transthoracic incremental monophasic versus biphasic defibrillation by emergency responders (TIMBER): a randomized comparison of monophasic with biphasic waveform ascending energy defibrillation for the resuscitation of out-of-hospital cardiac arrest due to ventricular fibrillation.

BACKGROUND: Although biphasic, as compared with monophasic, waveform defibrillation for cardiac arrest is increasing in use and popularity, whether it is truly a more lifesaving waveform is unproven. METHODS AND RESULTS: Consecutive adults with nontraumatic out-of-hospital ventricular fibrillation cardiac arrest were randomly allocated to defibrillation according to the waveform from automated external defibrillators administered by prehospital medical providers. The primary event of interest was admission alive to the hospital. Secondary events included return of rhythm and circulation, survival, and neurological outcome. Providers were blinded to automated defibrillator waveform. Of 168 randomized patients, 80 (48%) and 68 (40%) consistently received only monophasic or biphasic waveform shocks, respectively, throughout resuscitation. The prevalence of ventricular fibrillation, asystole, or organized rhythms at 5, 10, or 20 seconds after each shock did not differ significantly between treatment groups. The proportion of patients admitted alive to the hospital was relatively high: 73% in monophasic and 76% in biphasic treatment groups (P=0.58). Several favorable trends were consistently associated with receipt of biphasic waveform shock, none of which reached statistical significance. Notably, 27 of 80 monophasic shock recipients (34%), compared with 28 of 68 biphasic shock recipients (41%), survived (P=0.35). Neurological outcome was similar in both treatment groups (P=0.4). Earlier administration of shock did not significantly alter the performance of one waveform relative to the other, nor did shock waveform predict any clinical outcome after multivariate adjustment. CONCLUSIONS: No statistically significant differences in outcome could be ascribed to use of one waveform over another when out-of-hospital ventricular fibrillation was treated.

Manual chest compression vs use of an automated chest compression device during resuscitation following out-of-hospital cardiac arrest: a randomized trial.

CONTEXT: High-quality cardiopulmonary resuscitation (CPR) may improve both cardiac and brain resuscitation following cardiac arrest. Compared with manual chest compression, an automated load-distributing band (LDB) chest compression device produces greater blood flow to vital organs and may improve resuscitation outcomes. OBJECTIVE: To compare resuscitation outcomes following out-of-hospital cardiac arrest when an automated LDB-CPR device was added to standard emergency medical services (EMS) care with manual CPR. DESIGN, SETTING, AND PATIENTS: Multicenter, randomized trial of patients experiencing out-of-hospital cardiac arrest in the United States and Canada. The a priori primary population was patients with cardiac arrest that was presumed to be of cardiac origin and that had occurred prior to the arrival of EMS personnel. Initial study enrollment varied by site, ranging from late July to mid November 2004; all sites halted study enrollment on March 31, 2005. INTERVENTION: Standard EMS care for cardiac arrest with an LDB-CPR device (n = 554) or manual CPR (n = 517). MAIN OUTCOME MEASURES: The primary end point was survival to 4 hours after the 911 call. Secondary end points were survival to hospital discharge and neurological status among survivors. RESULTS: Following the first planned interim monitoring conducted by an independent data and safety monitoring board, study enrollment was terminated. No difference existed in the primary end point of survival to 4 hours between the manual CPR group and the LDB-CPR group overall (N = 1071; 29.5% vs 28.5%; P = .74) or among the primary study population (n = 767; 24.7% vs 26.4%, respectively; P = .62). However, among the primary population, survival to hospital discharge was 9.9% in the manual CPR group and 5.8% in the LDB-CPR group (P = .06, adjusted for covariates and clustering). A cerebral performance category of 1 or 2 at hospital discharge was recorded in 7.5% of patients in the manual CPR group and in 3.1% of the LDB-CPR group (P = .006). CONCLUSIONS: Use of an automated LDB-CPR device as implemented in this study was associated with worse neurological outcomes and a trend toward worse survival than manual CPR. Device design or implementation strategies require further evaluation. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00120965.

Pilot study of rapid infusion of 2 L of 4 degrees C normal saline for induction of mild hypothermia in hospitalized, comatose survivors of out-of-hospital cardiac arrest.

BACKGROUND: Recent clinical studies have demonstrated that mild hypothermia (32 degrees C to 34 degrees C) induced by surface cooling improves neurological outcome after resuscitation from out-of-hospital cardiac arrest. Results from animal models suggest that the effectiveness of mild hypothermia could be improved if initiated as soon as possible after return of spontaneous circulation. Infusion of cold, intravenous fluid has been proposed as a safe, effective, and inexpensive technique to induce mild hypothermia after cardiac arrest. METHODS AND RESULTS: In 17 hospitalized survivors of out-of-hospital cardiac arrest, we determined the effect on temperature and hemodynamics of infusing 2 L of 4 degrees C cold, normal saline during 20 to 30 minutes into a peripheral vein with a high-pressure bag. Data on vital signs, electrolytes, arterial blood gases, and coagulation were collected before and after fluid infusion. Cardiac function was assessed by transthoracic echocardiography before fluid administration and 1 hour after infusion. Passive (fans, leaving patient uncovered) or active (cooling blankets, neuromuscular blockade) cooling measures were used to maintain mild hypothermia for 24 hours. Infusion of 2 L of 4 degrees C cold, normal saline resulted in a mean temperature drop of 1.4 degrees C 30 minutes after the initiation of infusion. Rapid infusion of fluid was not associated with clinically important changes in vital signs, electrolytes, arterial blood gases, or coagulation parameters. The initial mean ejection fraction was 34%, and fluid infusion did not affect ejection fraction or increase central venous pressure, pulmonary pressures, or left atrial filling pressures as assessed by echocardiography. Passive measures were ineffective in maintaining hypothermia compared with active measures. CONCLUSIONS: Infusion of 2 L of 4 degrees C cold, normal saline is safe and effective in rapidly lowering body temperature in survivors of out-of-hospital cardiac arrest.

Automated external defibrillators: to what extent does the algorithm delay CPR?

STUDY OBJECTIVE: Maximizing cardiopulmonary resuscitation (CPR) during resuscitation may improve survival. Resuscitation protocols stack up to 3 shocks to achieve defibrillation, followed by an immediate postdefibrillation pulse check. The purpose of this study is to evaluate outcomes of rhythm reanalyses immediately after shock, stacked shocks, and initial postshock pulse checks in relation to achieving a pulse and initiating CPR. METHODS: We conducted an observational study of patients with ventricular fibrillation treated by first-tier emergency medical services (EMS). We collected data from EMS, dispatch, and hospital records. Additionally, we analyzed automatic external defibrillator recordings to determine the proportion of cardiac arrest victims who were defibrillated and achieved a pulse according to shock number (single versus stacked shock), proportion of victims with a pulse during the initial postdefibrillation pulse check, and interval from initial shock to CPR. RESULTS: The study included 481 cardiac arrest subjects. Automatic external defibrillators terminated ventricular fibrillation with the initial shock in 83.6% (n=402) of cases. A second shock terminated ventricular fibrillation in an additional 7.5% (n=36) of cases, and a third shock terminated ventricular fibrillation in 4.8% (n=23) of cases. The initial sequence of 3 shocks failed to terminate ventricular fibrillation in 4.1% (n=20) of cases. In total, automatic external defibrillators performed 560 rhythm reanalyses during the initial shock sequence and delivered 122 "stacked" shocks. Termination of ventricular fibrillation was not synonymous with return of a pulse. The initial shock produced a pulse that was eventually detected in 21.8% (105/481) of cases. Stacked shocks produced a pulse in 10.7% (13/122) of cases. For the 24.5 % (n=118) of cases in which a pulse returned, the pulse was detected during the initial postshock pulse check only 12 times, or 2.5% of all cases. The median interval from initial shock until CPR was 29 (23,41) seconds. CONCLUSION: Rhythm reanalyses, stacked shocks, and postshock pulse checks had low yield for achieving or detecting return of a pulse. CPR was not initiated until 29 seconds after the initial shock.