Initial Rhythm Of Ventricular Fibrillation Research Articles

Predictors of death among cardiac arrest patients after therapeutic hypothermia: A non-tertiary care center's initial experience

Introduction and ObjectivesTherapeutic hypothermia (TH) is recommended for patients with return of spontaneous circulation (ROSC) after cardiac arrest (CA). There is still uncertainty about management, target temperature and duration of TH. In the present study we aim to describe the initial experience of a non-tertiary care center with TH after CA and to determine predictors of mortality. MethodsDuring the period 2011-2014, out of 2279 patients hospitalized in the intensive care unit, 82 had a diagnosis of CA with ROSC. We determined predictors of mortality and neurological outcome in comatose patients with ROSC after CA treated by TH. ResultsA total of 15 patients were included, mean age 47.3±14 years, 10 (67.0%) male. CA occurred out-of-hospital (n=11; 73.3%) or in-hospital (n=4; 26.7%), in initial shockable (n=10; 66.7%) or non-shockable (n=5, 33.3%) rhythm. The mean time from CA to ROSC (CA-ROSC) was 44.7±36.5 min. All patients met the 24-hour TH target temperature of 33°C. The mean neuron-specific enolase (NSE) level was 93.7±109.0 μg/l. Seven patients (46.7%) were discharged with good cerebral performance and eight (53.3%) died. Patients who survived had lower median age (p=0.032), shorter CA-ROSC (p=0.048), lower NSE levels (p=0.020) and initial ventricular fibrillation rhythm (p=NS). ConclusionsThe effectiveness of TH appears to be related to younger age, shockable initial rhythm and shorter CA-ROSC time. This results indicates some lines of inquiry that should be developed in appropriate prospective studies. The role of biomarkers as predictors of prognosis is an open question, with NSE potentially playing an important role.

Abstract 14267: Clinical Characteristics of Patients With Out-of-hospital Cardiac Arrest Caused by Ventricular Fibrillation due to Acute Coronary Syndromes Who Responded to Extracorporeal Cardiopulmonary Resuscitation

Background: Extracorporeal cardiopulmonary resuscitation (ECRP) have been reported to be effective in patients with out-of-hospital cardiac arrest (OHCA) associated with an initial rhythm of ventricular fibrillation (VF) caused by acute coronary syndromes (ACS) refractory to conventional cardiopulmonary resuscitation (CPR). However, the clinical characteristics of patients who best respond to ECRP remain unclear. Methods: Between 2008 and 2012, we prospectively collected Utstein-style data at 46 institutions on 454 consecutive patients with OHCA aged 20 to 74 years had an initial rhythm of VF and arrived at the hospital within 45 minutes after the onset of cardiac arrest. They did not respond to conventional CPR given for more than 15 minutes after hospital arrival and received combination therapy with ECPR, percutaneous coronary intervention (PCI), intra-aortic balloon pumping (IABP), and therapeutic hypothermia (TH). ACS was diagnosed on emergency coronary angiography or clinical course in 133 patients. These patients were classified according to whether neurologic outcomes at 6 months, i.e., good outcome group (cerebral performance category [CPC] = 1 to 2) or poor outcome group (CPC = 3 to 5). Demographic characteristics were compared between two groups. Results: Among the 133 ACS patients given ECPR, good neurologic outcomes at 6 months in 14 (11%) patients, but not in 119 (89%) patients. There were no significant differences of age, the rate of witnessed arrest, bystander CPR, TH and time from hospital arrival to PCPS start between the 2 groups. Good outcome group had a shorter time from cardiac arrest to hospital arrival (24.9± 8.6 vs. 29.5± 10.1 min, p=0.03) and time from cardiac arrest to PCPS start (44 ± 8.8 vs. 53.7 ± 15.9 min, p=0.01) than poor outcome group. Conclusions: Our results suggest that shortening the interval from cardiac arrest until PCPS start, especially until hospital arrival, may improve neurologic outcomes in patients with refractory VF caused by ACS.

Amplitude-spectral area and chest compression release velocity independently predict hospital discharge and good neurological outcome in ventricular fibrillation out-of-hospital cardiac arrest

ObjectiveIn out-of-hospital cardiac arrest (OHCA) with ventricular fibrillation (VF) the frequency-based waveform characteristic, amplitude-spectral area (AMSA) is associated with hospital discharge and good neurological outcome, yet AMSA is also known to increase in response to chest compressions (CC). In addition to rate and depth, well performed CC provides good chest recoil without leaning, reflected in the release velocity (RV). We hypothesized that AMSA is associated with hospital discharge and good neurological outcome independent of CC quality. MethodsOHCA patients (age≥18), with initial rhythm of VF from an Utstein-Style database were analyzed. AMSA was measured prior to each shock, and averaged for each subject (AMSA-avg). Primary endpoint was hospital discharge and secondary endpoint was a good neurological outcome. Univariate and stepwise multivariable logistic regression, and receiver–operator–characteristic (ROC) analyses were performed. Factors analyzed were age, sex, witnessed status, time from dispatch to monitor/defibrillator application, number of shocks, first shock AMSA (AMSA1), AMSA-avg, averaged pre-shock pause, CC rate, depth, and RV. Results140 subjects were analyzed. Hospital discharge was 31% and with good neurological outcome in 24% (77% of those discharged). AMSA-avg (p<0.001), RV (p=0.002), and age (p=0.029) were independently associated with hospital discharge, with a non-significant trend for witnessed status (p=0.069), with AUC=0.846 for the multivariate model. For good neurological outcome, AMSA-avg (p=0.001) and RV (p=0.001) remained independently significant, with AUC=0.782. ConclusionIn OHCA with an initial rhythm of VF, AMSA-avg and CC RV are both highly and independently associated with hospital discharge and good neurological outcome.

Abstract 12769: Amplitude-Spectral Area of the Ventricular Fibrillation Waveform and Chest Compression Quality in Witnessed and Unwitnessed Out-Of-Hospital Cardiac Arrest: Can We Predict Who is Unlikely to Survive?

Background: Previous investigations in human out of hospital cardiac arrest (OHCA) due to ventricular fibrillation (VF) have shown that the frequency-based waveform characteristic, amplitude spectral area (AMSA) predicts defibrillation success and is associated with survival to hospital discharge. We evaluated the relative strength of factors associated with hospital discharge including witnessed/unwitnessed status, chest compression (CC) quality and AMSA. We then investigated if there is a threshold value for AMSA that can identify patients who are unlikely to survive. Methods: Adult OHCA patients (age ≥18), with initial rhythm of VF from an Utstein-Style database (collected from 2 EMS systems) were analyzed. AMSA was measured from the waveform immediately prior to each shock, and averaged for each individual subject (AMSA-ave). Univariate and stepwise multivariable logistic regression, and receiver-operator-characteristic (ROC) analyses were performed. Factors analyzed: age, sex, witnessed status, time from dispatch to monitor/defibrillator application, number of shocks, mean CC rate, depth, and release velocity (RV). Results: 140 subjects were analyzed, [104 M (74%), age 62 ± 14 yrs, witnessed 65%]. Survival was 38% in witnessed and 16% in unwitnessed arrest. In univariate analyses, age (P=0.001), witnessed status (P=0.009), AMSA-ave (P&lt;0.001), mean CC depth (P=0.025), and RV (P&lt; 0.001) were associated with survival. Stepwise logistic regression identified AMSA-ave (P&lt;0.001), RV (P=0.001) and age (P=0.018) as independently associated with survival. The area under the curve (ROC analysis) was 0.849. The probability of survival was &lt; 5% in witnessed arrest for AMSA-ave &lt; 5 mV-Hz, and in unwitnessed arrest for AMSA-ave &lt; 15 mV-Hz. Conclusion: In OHCA with an initial rhythm of VF, AMSA-ave and CC RV are highly associated with survival. Further study is needed to evaluate whether AMSA-ave may be useful to identify patients highly unlikely to survive.

Association of Amplitude Spectral Area of the Ventricular Fibrillation Waveform With Survival of Out-of-Hospital Ventricular Fibrillation Cardiac Arrest

BackgroundPrevious investigations of out-of-hospital cardiac arrest (OHCA) have shown that the waveform characteristic amplitude spectral area (AMSA) can predict successful defibrillation and return of spontaneous circulation (ROSC) but has not been studied previously for survival. ObjectivesTo determine whether AMSA computed from the ventricular fibrillation (VF) waveform is associated with pre-hospital ROSC, hospital admission, and hospital discharge. MethodsAdults with witnessed OHCA and an initial rhythm of VF from an Utstein style database were studied. AMSA was measured prior to each shock and averaged for each subject (AMSA-avg). Factors such as age, sex, number of shocks, time from dispatch to monitor/defibrillator application, first shock AMSA, and AMSA-avg that could predict pre-hospital ROSC, hospital admission, and hospital discharge were analyzed by logistic regression. ResultsEighty-nine subjects (mean age 62 ± 15 years) with a total of 286 shocks were analyzed. AMSA-avg was associated with pre-hospital ROSC (p = 0.003); a threshold of 20.9 mV-Hz had a 95% sensitivity and a 43.4% specificity. Additionally, AMSA-avg was associated with hospital admission (p < 0.001); a threshold of 21 mV-Hz had a 95% sensitivity and a 54% specificity and with hospital discharge (p < 0.001); a threshold of 25.6 mV-Hz had a 95% sensitivity and a 53% specificity. First-shock AMSA was also predictive of pre-hospital ROSC, hospital admission, and discharge. Time from dispatch to monitor/defibrillator application was associated with hospital admission (p = 0.034) but not pre-hospital ROSC or hospital discharge. ConclusionsAMSA is highly associated with pre-hospital ROSC, survival to hospital admission, and hospital discharge in witnessed VF OHCA. Future studies are needed to determine whether AMSA computed during resuscitation can identify patients for whom continuing current resuscitation efforts would likely be futile.

Use of esmolol after failure of standard cardiopulmonary resuscitation to treat patients with refractory ventricular fibrillation

IntroductionWe compare the outcomes for patients who received esmolol to those who did not receive esmolol during refractory ventricular fibrillation (RVF) in the emergency department (ED). MethodsA retrospective investigation in an urban academic ED of patients between January 2011 and January 2014 of patients with out-of-hospital or ED cardiac arrest (CA) with an initial rhythm of ventricular fibrillation (VF) or ventricular tachycardia (VT) who received at least three defibrillation attempts, 300mg of amiodarone, and 3mg of adrenaline, and who remained in CA upon ED arrival. Patients who received esmolol during CA were compared to those who did not. Results90 patients had CA with an initial rhythm of VF or VT; 65 patients were excluded, leaving 25 for analysis. Six patients received esmolol during cardiac arrest, and nineteen did not. All patients had ventricular dysrhythmias refractory to many defibrillation attempts, including defibrillation after administration of standard ACLS medications. Most received high doses of adrenaline, amiodarone, and sodium bicarbonate. Comparing the patients that received esmolol to those that did not: 67% and 42% had temporary return of spontaneous circulation (ROSC); 67% and 32% had sustained ROSC; 66% and 32% survived to intensive care unit admission; 50% and 16% survived to hospital discharge; and 50% and 11% survived to discharge with a favorable neurologic outcome, respectively. ConclusionBeta-blockade should be considered in patients with RVF in the ED prior to cessation of resuscitative efforts.

Resumption of chest compressions after successful defibrillation and risk for recurrence of ventricular fibrillation in out-of-hospital cardiac arrest.

Prior investigation of out-of-hospital cardiac arrest has raised the concern that ventricular fibrillation (VF) recurrence may be triggered by chest compression (CC) resumption. We investigated predictors of VF recurrence after defibrillation, including timing of CC resumption. Patients with witnessed out-of-hospital cardiac arrest and initial rhythm of VF from an Utstein-style database were analyzed. For each shock that defibrillated VF, CC resumption and VF recurrence times were determined. Shocks were classified according to postshock rhythm. Factors (age, sex, time from dispatch to monitor/defibrillator application, and CC resumption) that could predict VF recurrence were analyzed. CC resumption was categorized into groups: CC1, 1 to 5 seconds; CC2, 6 to 10 seconds; CC3, 11 to 30 seconds; and CC4, >30 seconds. Eighty-eight subjects were analyzed, with a total of 285 shocks, with 226 shocks that achieved asystole (n=102), organized rhythm (n=120), or monomorphic ventricular tachycardia (n=4). After a successful shock, CC resumption occurred at a median (interquartile range) of 8 (5-18) seconds. VF recurred after 166 shocks (74%) and recurred within 30 seconds in 69 shocks. There was no significant relationship between VF recurrence and factors analyzed including CC resumption time, nor stratified by postshock rhythm. The hazard ratios (HRs) for VF recurrence within 30 seconds for later CC groups (CC2, CC3, and CC4) relative to early CC resumption (CC1) were as follows: HR(CC2)=1.05 (P=0.9); HR(CC3)=1.75 (P=0.1); and HR(CC4)=0.67 (P=0.4). VF recurrence within 30 seconds of a defibrillatory shock was not dependent on timing of CC resumption in patients with witnessed arrest and initial rhythm of VF.

Hemodynamic factors related to recovery ad integrum patient in ventricular fibrillation

Objective: Our study analyzes which factors of patient's hemodynamic state could be related with the probability of survival and neurological recovery in OOHCA with initial rhythm of VF (ventricular fibrillation).

Evaluation of pre-hospital administration of adrenaline (epinephrine) by emergency medical services for patients with out of hospital cardiac arrest in Japan: controlled propensity matched retrospective cohort study

Objectives To evaluate the effectiveness of pre-hospital adrenaline (epinephrine) administered by emergency medical services to patients with out of hospital cardiac arrest.Design Controlled propensity matched retrospective cohort study, in which...

Abstract 241: Amplitude Spectrum Area as a Tool to Identify the Circulatory Phase of Ventricular Fibrillation

Background: Ventricular fibrillation (VF) cardiac arrest (CA) is characterized by 3 time dependent phases: electrical (shorter than 4min), circulatory (4-10min), and metabolic (longer than 10min). These phases reflect the progressive increase of myocardial ischemia and suggest the potentially optimal treatment. During the electrical phase, immediate defibrillation is likely to be successful, while during the circulatory phase, the success of defibrillation diminishes without CPR. In the metabolic phase, there is low likelihood of successful resuscitation and probably a longer CPR interval prior to defibrillation is necessary. In the out-of-hospital (OH) setting, most patients may have passed the electrical phase when EMS arrives. Identification of the VF phase may therefore facilitate the proper CPR treatment. We used AMSA to determine if patients were in circulatory or in metabolic phase at EMS arrival. Methods: Data from an Utstein-compliant registry along with electronic ECG records were collected on consecutive adult OHCA patients treated by 2 EMS agencies over a 2 year period. Patients with bystander witnessed CA and with VF as initial CA rhythm were included (n=41). AMSA was calculated in earliest pause without compression artifacts, using a 2 sec ECG with a Tukey (0.2) FFT window. VF duration was calculated as the sum of the time interval from collapse to defibrillator on and the time interval from defibrillator on to first CPR interruption for defibrillation delivery. Results: VF duration ranged between 6.5 and 29.6 min (11.3+4.1 min), with a corresponding AMSA between 2.1 and 16.4 mV-Hz (9.4+4.2 mV-Hz). AMSA measured in the circulatory phase (N=19) was significantly higher than that in the metabolic phase (N=22) (8.14+3.17 vs. 5.98+2.88, p=0.03). Linear regression revealed that AMSA decreases by 0.22 mV-Hz for every min of VF. AMSA was able to predict circulatory phase with an accuracy of 0.7 in ROC area. An AMSA threshold of 10 mV-Hz was able to predict the circulatory phase with sensitivity of 32%, specificity of 95%, PPV of 86%, NPV of 62% and overall accuracy of 66%. Conclusions: AMSA is a good indicator of downtime in OHCA with initial rhythm of VF. AMSA could be used to identify VF phase and thereby suggest for the proper CPR intervention.

A new method to estimate the amplitude spectrum analysis of ventricular fibrillation during cardiopulmonary resuscitation

AIMSAccurate ventricular fibrillation (VF) waveform analysis usually requires rescuers to discontinue cardiopulmonary resuscitation (CPR). However, prolonged “hands-off” time has a deleterious impact on the outcome. We developed a new filter technique that could clean the CPR artifacts and help preserve the shockability index of VF METHODSWe analyzed corrupted ECGs, which were constructed by randomly adding different scaled CPR artifacts to the VF waveforms. A newly developed algorithm was used to identify the CPR fluctuations. The algorithm contained two steps. First, decomposing the raw data by empirical mode decomposition (EMD) into several intrinsic mode fluctuations (IMFs) and combining the dominant IMFs to reconstruct a new signal. Second, calculating each CPR cycle frequency from the new signal and fitting the new signal to the original corrupted ECG by least square mean (LSM) method to derive the CPR artifacts. The estimated VF waveform was derived by subtraction of the CPR artifacts from the corrupted ECG. We then performed amplitude spectrum analysis (AMSA) for original VF, corrupted ECG and estimated VF. RESULTSA total of 150 OHCA subjects with initial VF rhythm were included for analysis. Ten CPR artifacts signals were used to construct corrupted ECG. Even though the correlations of AMSA between the corrupted ECG vs. the original VF and the estimated VF vs. the original VF are all high (all p<0.001), the values of AMSA were obviously biased in corrupted ECG with wide limits of agreement in Bland–Altman mean-difference plot. ROC analysis of the AMSA in the prediction of defibrillation success showed that the new algorithm could preserve the cut-off AMSA value for CPR artifacts with power ratio to VF from 0 to 6dB. CONCLUSIONThe new algorithm could efficiently filter the CPR-related artifacts of the VF ECG and preserve the shockability index of the original VF waveform.

Analysis of amplitude spectral area and slope to predict defibrillation in out of hospital cardiac arrest due to ventricular fibrillation (VF) according to VF type: Recurrent versus shock-resistant

BackgroundIn out-of-hospital cardiac arrest (OHCA) due to ventricular fibrillation (VF), VF may recur during resuscitation (recurrent VF) or fail to defibrillate (shock-resistant VF). While retrospective studies have suggested that amplitude spectral area (AMSA) and slope predict defibrillation, it is unknown whether the predictive power is influenced by VF type. We hypothesized that in witnessed OHCA with initial rhythm of VF that the utility for AMSA and slope to predict defibrillation would differ between shock-resistant and recurrent VF. MethodsAMSA and slope were measured immediately prior to each shock. For second or later shocks, VF was classified as recurrent or shock-resistant. Cardiac arrest was classified according to whether the majority of shocks were for recurrent VF or shock-resistant VF. Results44 patients received 98 shocks for recurrent VF and 96 shocks for shock-resistant VF; 24 patients achieved ROSC in the field. AMSA and slope were higher in recurrent VF compared to shock-resistant VF (AMSA: 28.8±13.1 vs 15.2±8.6mVHz, P<0.001, and slope: 2.9±1.4 vs 1.4±1.0mVs−1, P=0.001). Recurrent VF was more likely to defibrillate than shock-resistant VF (P<0.001). AMSA and slope predicted defibrillation in shock-resistant VF (P<0.001 for both AMSA and slope) but not in recurrent VF. Recurrent VF predominated in 79% of patients that achieved ROSC compared to 55% that did not (P=0.10). ConclusionsIn witnessed OHCA with VF as initial rhythm, recurrent VF is associated with higher values of AMSA and slope and is likely to re-defibrillate. However, when VF is shock-resistant, AMSA and slope are highly predictive of defibrillation.

Abstract 216: How Many Shocks Should Be Given to Victims with Out-of-Hospital Cardiac Arrest with Shockable Rhythm On-site Before Transportation?

Early defibrillation and high quality cardio-pulmonary resuscitation (CPR) are the key of survival with minimal neurologic impairment (good neurological survival (GNS)) in out-of-hospital cardiac arrest (OHCA) cases. But it has not been clarified how long emergency medical service (EMS) personnel stay on site of OHCA and give CPR with defibrillation before transportation to the hospital. To clarify this, we examined the relationship between the number of defibrillation and the rate of GNS which was defined as the Glasgow-Pittsburgh cerebral performance category of 1 or 2 after one month of OHCA. Methods and Results. From January 1, 2005, through December 31, 2009, we conducted a prospective, population-based, observational study involving the consecutive patients across Japan who had OHCA (n=547,218). Since the defibrillation protocol of one shock followed by immediate chest compression and ventilation for 2 minutes had started from January 1, 2007 in Japan, we analyzed from January 1, 2007 to December 31, 2009. We identified 13,152 EMS-treated, witnessed cardiac arrest cases, with the age &gt;18 years old, with the initial rhythm of ventricular fibrillation or tachycardia (VF/VT). Results were shown in the figure. The intervals from witness to start CPR and the rates of by-stander CPR given by citizen were not different among each group. GNS rate was decreased as the number of defibrillation was increased, but GNS rate was still over 10% in the group of 8 shocks. Conclusions. In conclusion, up to two shocks on site before transportation would be acceptable (because GNS was more than 20%), and CPR with defibrillation should not be stopped during transportation as long as VF/VT persists.

Impact of resuscitation system errors on survival from in-hospital cardiac arrest

BackgroundAn estimated 350,000–750,000 adult, in-hospital cardiac arrest (IHCA) events occur annually in the United States. The impact of resuscitation system errors on survival during IHCA resuscitation has not been evaluated. The purpose of this paper was to evaluate the impact of resuscitation system errors on survival to hospital discharge after IHCA. Methods and resultsWe evaluated subjective and objective errors in 118,387 consecutive, adult, index IHCA cases entered into the Get with the Guidelines National Registry of Cardiopulmonary Resuscitation database from January 1, 2000 through August 26, 2008. Cox regression analysis was used to determine the relationship between reported resuscitation system errors and other important clinical variables and the hazard ratio for death prior to hospital discharge. Of the 108,636 patients whose initial IHCA rhythm was recorded, resuscitation system errors were committed in 9,894/24,467 (40.4%) of those with an initial rhythm of ventricular fibrillation or pulseless ventricular tachycardia (VF/pVT) and in 22,599/84,169 (26.8%) of those with non-VF/pVT. The most frequent system errors related to delay in medication administration (>5min time from event recognition to first dose of a vasoconstrictor), defibrillation, airway management, and chest compression performance errors. The presence of documented resuscitation system errors on an IHCA event was associated with decreased rates of return of spontaneous circulation, survival to 24h, and survival to hospital discharge. The relative risk of death prior to hospital discharge based on hazard ratio analysis was 9.9% (95% CI 7.8, 12.0) more likely for patients whose initial documented rhythm was non-VF/pVT when resuscitation system errors were reported compared to when no errors were reported. It was 34.2% (95% CI 29.5, 39.1) more likely for those with VF/pVT. ConclusionsThe presence of resuscitation system errors that are evident from review of the resuscitation record is associated with decreased survival from IHCA in adults. Hospitals should target the training of first responders and code team personnel to emphasize the importance of early defibrillation, early use of vasoconstrictor medication, and compliance with ACLS protocols.

Induced Hypothermia Following Cardiac Arrest And Subsequent Neurological Outcomes: An Audit

Background: Survival with good neurological recovery following cardiac arrest is poor. A number of recent studies have concluded that the use of induced hypothermia can improve survival and limit the level of neurological impairment following cardiac arrest. Objective: To audit survival and neurological recovery outcomes in patients treated with induced hypothermia within the Intensive Care Unit (ICU) following cardiac arrest.Design: A two year retrospective study.Method: Data from patient notes were extracted and analysed.Conclusion: The survival rate for patients presenting with a cardiac arrest and an initial rhythm of ventricular fibrillation (VF) is 62%, with 58% of patients surviving with good neurological recovery. Of those who were treated conservatively following a cardiac arrest with an initial rhythm of VF, 20% survived with good neurological recovery.

Therapeutic hypothermia after cardiac arrest: implementation in UK intensive care units

In 2003 the International Liaison Committee on Resuscitation (ILCOR) published guidelines recommending all patients admitted comatose to hospital following an out-of-hospital cardiac arrest (OHCA) with an initial rhythm of ventricular fibrillation should be treated with therapeutic hypothermia for a period of 12 to 24 hours [1]. We aimed to determine how many units are using hypothermia as part of their post-cardiac arrest management and when each of the ICUs implemented the therapy. Other objectives were to determine what cooling techniques are being used, the target temperature and the duration of cooling used.

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*

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. A retrospective study of patients who presented after implementation of a therapeutic hypothermia protocol compared with those who presented before the protocol was implemented. Harborview Medical Center, Seattle, WA. A total of 491 consecutive adults with out-of-hospital, nontraumatic cardiac arrest who presented between January 1, 2000 and December 31, 2004. 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. 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. 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.

Improved Patient Survival Using a Modified Resuscitation Protocol for Out-of-Hospital Cardiac Arrest

Cardiac arrest continues to have poor survival in the United States. Recent studies have questioned current practice in resuscitation. Our emergency medical services system made significant changes to the adult cardiac arrest resuscitation protocol, including minimizing chest compression interruptions, increasing the ratio of compressions to ventilation, deemphasizing or delaying intubation, and advocating chest compressions before initial countershock. This retrospective observational cohort study reviewed all adult primary ventricular fibrillation and pulseless ventricular tachycardia cardiac arrests 36 months before and 12 months after the protocol change. Primary outcome was survival to discharge; secondary outcomes were return of spontaneous circulation and cerebral performance category. Survival of out-of-hospital arrest of presumed primary cardiac origin improved from 7.5% (82 of 1097) in the historical cohort to 13.9% (47 of 339) in the revised protocol cohort (odds ratio, 1.80; 95% confidence interval, 1.19 to 2.70). Similar increases in return of spontaneous circulation were achieved for the subset of witnessed cardiac arrest patients with initial rhythm of ventricular fibrillation from 37.8% (54 of 143) to 59.6% (34 of 57) (odds ratio, 2.44; 95% confidence interval, 1.24 to 4.80). Survival to hospital discharge also improved from an unadjusted survival rate of 22.4% (32 of 143) to 43.9% (25 of 57) (odds ratio, 2.71; 95% confidence interval, 1.34 to 1.59) with the protocol. Of the 25 survivors, 88% (n=22) had favorable cerebral performance categories on discharge. The changes to our prehospital protocol for adult cardiac arrest that optimized chest compressions and reduced disruptions increased the return of spontaneous circulation and survival to discharge in our patient population. These changes should be further evaluated for improving survival of out-of-hospital cardiac arrest patients.

Regional variation in out-of-hospital cardiac arrest incidence and outcome.

The health and policy implications of regional variation in incidence and outcome of out-of-hospital cardiac arrest remain to be determined. To evaluate whether cardiac arrest incidence and outcome differ across geographic regions. Prospective observational study (the Resuscitation Outcomes Consortium) of all out-of-hospital cardiac arrests in 10 North American sites (8 US and 2 Canadian) from May 1, 2006, to April 30, 2007, followed up to hospital discharge, and including data available as of June 28, 2008. Cases (aged 0-108 years) were assessed by organized emergency medical services (EMS) personnel, did not have traumatic injury, and received attempts at external defibrillation or chest compressions or resuscitation was not attempted. Census data were used to determine rates adjusted for age and sex. Incidence rate, mortality rate, case-fatality rate, and survival to discharge for patients assessed or treated by EMS personnel or with an initial rhythm of ventricular fibrillation. Among the 10 sites, the total catchment population was 21.4 million, and there were 20,520 cardiac arrests. A total of 11,898 (58.0%) had resuscitation attempted; 2729 (22.9% of treated) had initial rhythm of ventricular fibrillation or ventricular tachycardia or rhythms that were shockable by an automated external defibrillator; and 954 (4.6% of total) were discharged alive. The median incidence of EMS-treated cardiac arrest across sites was 52.1 (interquartile range [IQR], 48.0-70.1) per 100,000 population; survival ranged from 3.0% to 16.3%, with a median of 8.4% (IQR, 5.4%-10.4%). Median ventricular fibrillation incidence was 12.6 (IQR, 10.6-5.2) per 100,000 population; survival ranged from 7.7% to 39.9%, with a median of 22.0% (IQR, 15.0%-24.4%), with significant differences across sites for incidence and survival (P<.001). In this study involving 10 geographic regions in North America, there were significant and important regional differences in out-of-hospital cardiac arrest incidence and outcome.

The impact of prehospital transport interval on survival in out-of-hospital cardiac arrest: Implications for regionalization of post-resuscitation care

There is growing evidence that therapeutic hypothermia and other post-resuscitation care improves outcomes in out-of-hospital cardiac arrest (OHCA). Thus, transporting patients with return of spontaneous circulation (ROSC) to specialized facilities may increase survival rates. However, it is unknown whether prolonging transport to reach a designated facility would be detrimental. Data from OHCA patients treated in EMS systems that cover approximately 70% of Arizona's population were evaluated (October 2004-December 2006). We analyzed the association between transport interval (depart scene to ED arrival) and survival to hospital discharge in adult, non-traumatic OHCA patients and in the subgroup who achieved ROSC and remained comatose. 1846 OHCA occurred prior to EMS arrival. Complete transport interval data were available for 1177 (63.8%) patients (study group). 253 patients (21.5%) achieved ROSC and remained comatose making them theoretically eligible for transport to specialized care. Overall, 70 patients (5.9%) survived and 43 (17.0%) comatose ROSC patients survived. Mean transport interval for the study group was 6.9 min (95% CI: 6.7, 7.1). Logistic regression revealed factors that were independently associated with survival: witnessed arrest, bystander CPR, method of CPR, initial rhythm of ventricular fibrillation, and shorter EMS response time interval. There was no significant association between transport interval and outcome in either the overall study group (OR=1.2; 0.77, 1.8) or in the comatose, ROSC subgroup (OR 0.94; 0.51, 1.8). Survival was not significantly impacted by transport interval. This suggests that a modest increase in transport interval from bypassing the closest hospital en route to specialized care is safe and warrants further investigation.