Long-term changes in the incidence of out-of-hospital ventricular fibrillation

Aim of the study

To report the long-term changes in the incidence of out-of-hospital ventricular fibrillation (VF), and also to report concurrent changes in the possible explanatory factors for the change.

Methods

This was a retrospective observational study. All bystander-witnessed out-of-hospital cardiac arrests (with a known initial rhythm) in Helsinki, Finland during 1.1.1994-31.12.2007 were included in the study. High (years 1994-1996) and low (2002-2004) incidence periods for VF were defined and compared.

Results

There were 3131 bystander-witnessed out-of-hospital cardiac arrests of which 3118 (99.6%) had a known initial rhythm. During 2000-2007 the annual incidence of bystander witnessed ventricular fibrillation (VF) was 11.6 (95% CI 9.7-13.5) per 100,000 inhabitants. In 1994-1996 VF was 1.8 times more likely than in 2002-2004, after adjustment for several patient related factors and EMS related factors. Arrests with cardiac aetiology became less common, as 54.8% arrests had a cardiac cause in 1994-1996 compared to 45.2% in 2002-2004 (p < 0.001). Of cardiac arrests with cardiac aetiology, 60.6% presented with VF in 1994-1996 compared to 45.7% in 2002-2004 (p < 0.001). There were major changes in the possible explanatory factors during the study period.

Conclusion

The decline in the incidence of out-of-hospital VF seems to have ended, and the annual incidence of VF has stabilised to 11.6 (95% CI 9.7-13.5) per 100,000 inhabitants. During the period of lower incidence of VF, cardiac aetiology caused fewer arrests, and these arrests did not present with VF as often as previously.     

Assessment of a three-phase model of out-of-hospital cardiac arrest in patients with ventricular fibrillation

AIM: Cardiac arrest with ventricular fibrillation (VF) has been divided into three phases in which phase-specific therapy may improve outcome. The aim of this study was to assess the relationship between call-to-shock time, bystander CPR (BCPR), and cardiac arrest outcomes. METHODS: In a retrospective analysis of prospectively-acquired data from witnessed VF out-of-hospital cardiac arrests (OHCA), patients were classified as phases 1, 2, or 3 based on call-to-shock time (<5, 5-8, and >8 min) and further stratified based on performance of BCPR. Groups were compared with regard to survival, neurological outcome, and restoration of spontaneous circulation (ROSC) with defibrillation only (no ALS interventions to achieve sustained ROSC). RESULTS: Survival, neurologically intact survival, and ROSC with defibrillation were different between phases 1 and 2 (p=0.014 and p=0.005, p<0.01) but not between phases 2 and 3. Patients were further classified as having received BCPR (N=111) or no BCPR (N=107). Neurologically intact survival with and without BCPR, respectively, was 61% versus 72% (phase 1), 44% versus 41% (phase 2), and 42% versus 29% (phase 3). ROSC with defibrillation only with and without BCPR, respectively, was 64% versus 56% (phase 1), 37.0% versus 29% (phase 2), and 33% versus 8% (phase 3). ROSC with defibrillation alone was statistically higher in univariate analysis in phase 3 with BCPR (p=0.033) but not in multivariate analysis (p=0.068). CONCLUSIONS: BCPR did not significantly improve survival in any phase of OHCA, though there was a trend toward increased neurologically intact survival and increased ROSC with defibrillation alone in phase 3.     

Recurrent ventricular fibrillation during advanced life support care of patients with prehospital cardiac arrest

AIM OF THE STUDY: The response of recurrent episodes of ventricular fibrillation (VF) to defibrillation shocks has not been systematically studied. We analyzed outcomes from countershocks delivered for VF during advanced life support (ALS) care of patients with out-of-hospital cardiac arrest. METHODS: Cohort of patients with prehospital cardiac arrest presenting with VF, treated by ALS ambulance staff following ERC Guidelines 2000. Biphasic defibrillators provided shocks increasing from 200 to 360J. Recorded signals were analyzed to determine, for each shock, if VF was terminated and if a sustained organized rhythm was restored within 60s. RESULTS: In 465 of the 467 patients enrolled, the initial VF episode was terminated within three shocks: 92%, 61%, and 83% responded to 200J first, 200J second and 360J third shocks, respectively. VF recurred in 48% of patients within 2min of the first episode, and in 74% sometime during prehospital care. In the 175 patients experiencing five or more VF episodes, single shock VF termination dropped from the first to the fifth episode (90-80%, p<0.001) without change in transthoracic impedance, yet the proportion returning to organized rhythms increased (11-42%, p<0.0001). CONCLUSIONS: Repeated refibrillation is common in patients with VF cardiac arrest. The likelihood of countershocks to terminate VF declines for repeated episodes of VF, yet shocks that terminate these episodes result increasingly in a sustained organized rhythm.     

King LT-D use by urban basic life support first responders as the primary airway device for out-of-hospital cardiac arrest

Objective

The objective of this study was to compare the frequency of first attempt success between basic life support (BLS) first responder initiated King LT-D placement and paramedic initiated endotracheal intubation (ETI) among patients experiencing out-of-hospital cardiac arrest (OOHCA).

Methods

In 2009 a large, urban EMS agency modified their out-of-hospital, non-traumatic, cardiac arrest protocol from paramedic initiated ETI to first responder initiated King LT-D placement. This retrospective analysis of all adult, non-traumatic cardiac arrests occurred four months before and four months after protocol implementation. The outcome variable in this analysis was first attempt airway management success defined as placement of the device with end tidal CO₂ wave form or colorimetric color change, auscultation of bilateral breath sounds, and improved or normal pulse oximetry reading. The independent variable of interest was initial device utilized to secure the airway, King LT-D or ETI.

Results

There were 351 adult, non-traumatic OOHCAs with 184 patients (52.4%) enrolled during the ETI period and 167 (47.6%) during the King LT-D period. The frequency of first attempt success was 57.6% in the ETI group and 87.8% in the King LT-D group. Patients in the King LT-D group were significantly more likely to experience first attempt success versus standard ETI methods (OR 5.3; 95%CI 2.9-9.5).

Conclusion

In this analysis of OOHCA airway management, first attempt BLS King LT-D placement success exceeded that of first attempt paramedic ETI success. In addition, patients in the King LT-D group were more likely to have had an advanced airway attempted and to have had a successful advanced airway placed when multiple attempts were required.     

Gender and survival after sudden cardiac arrest: A systematic review and meta-analysis

BackgroundConflicting results exist regarding the impact of gender on early survival after sudden cardiac arrest (SCA). We aimed to assess the association between female gender and early SCA survival.MethodsWe searched Embase, MEDLINE, EBM Reviews, Cochrane Central Register of Controlled Trials, and Cochrane Database of Systematic Reviews (between 1948 and January 2014) for studies evaluating the association between gender and survival after SCA. Two independent reviewers selected studies of any design or language. Pooled odds-ratios (OR) and 95% confidence intervals (CIs) were estimated using a random-effects model. Additional sensitivity analyses and meta-regression were carried out to explore heterogeneity.ResultsThirteen studies were included involving 409,323 patients. Women were more likely to present with SCA at home, less likely to have witnessed SCA, had a lower frequency of initial shockable rhythm but were more likely to receive bystander CPR. After adjustment for these differences, women were more likely to survive at hospital discharge (OR 1.1, 95% CI 1.03–1.20, p = 0.006, I² = 61%). This association persisted in multiple sensitivity analyses.ConclusionThis meta-analysis of observational studies demonstrates that women have increased odds of survival after SCA. Further studies are needed to address mechanisms explaining this discrepancy.     

Detection of ventricular fibrillation in the presence of cardiopulmonary resuscitation artefacts

Providing cardiopulmonary resuscitation (CPR) to a patient in cardiac arrest introduces artefacts into the electrocardiogram (ECG), corrupting the diagnosis of the underlying heart rhythm. CPR must therefore be discontinued for reliable shock advice analysis by an automated external defibrillator (AED). Detection of ventricular fibrillation (VF) during CPR would enable CPR to continue during AED rhythm analysis, thereby increasing the likelihood of resuscitation success. This study presents a new adaptive filtering method to clean the ECG. The approach consists of a filter that adapts its characteristics to the spectral content of the signal exclusively using the surface ECG that commercial AEDs capture through standard patches. A set of 200 VF and 25 CPR artefact samples collected from real out-of-hospital interventions were used to test the method. The performance of a shock advice algorithm was evaluated before and after artefact removal. CPR artefacts were added to the ECG signals and four degrees of corruption were tested. Mean sensitivities of 97.83%, 98.27%, 98.32% and 98.02% were achieved, producing sensitivity increases of 28.44%, 49.75%, 59.10% and 64.25%, respectively, sufficient for ECG analysis during CPR. Although satisfactory and encouraging sensitivity values have been obtained, further clinical and experimental investigation is required in order to integrate this type of artefact suppressing algorithm in current AEDs.     

Survival rate and factors associated with 1-month survival of witnessed out-of-hospital cardiac arrest of cardiac origin with ventricular fibrillation and pulseless ventricular tachycardia: the Utstein Osaka project

OBJECTIVE: We reassessed 1-month survival of patients with witnessed out-of-hospital cardiac arrest (OHCA) of cardiac origin with ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT) in Osaka, Japan, and identified factors associated with 1-month survival using updated data from 1998 to 2004 collected based on the Utstein Style. METHODS: Using the Utstein Osaka Project database, we analyzed 1028 cases which met the following criteria: (1) patient age 18 years or older; (2) presumed cardiac origin based on the definition of the Utstein Style; (3) witnessed by citizens; (4) VF or pulseless VT at the time of arrival of the ambulance. The main outcome measure was survival at 1 month after collapse. Variables to develop a predictive model for 1-month survival were selected by stepwise logistic regression. RESULTS: Survival at 1 month was 19.6%. Factors retained in the final logistic regression were age, sex, type of witness, and time interval from (a) ambulance call receipt to cardiopulmonary resuscitation (CPR) by the ambulance crew; (b) ambulance call to defibrillation; (c) CPR by the ambulance crew to hospital arrival. Area under the receiver-operating characteristic curve for the model developed with the six variables was 0.738 and Hosmer-Lemshow goodness-of-fit p-value was 0.94. CONCLUSION: We successfully developed a model to estimate the probability of 1-month survival using variables easy to collect in the early phase of resuscitation, and this model would help physicians and family members predict the likelihood of 1-month survival of OHCA patients on admission.     

Performance of a rectilinear biphasic waveform in defibrillation of presenting and recurrent ventricular fibrillation: a prospective multicenter study

Objectives

We tested the hypothesis that shock success differs with initial and recurrent episodes of ventricular fibrillation (VF).

Methods

From September 2008 to March 2010 out-of-hospital cardiac arrest patients with VF as the initial rhythm at 9 study sites were defibrillated by paramedics using a rectilinear biphasic waveform. Shock success was defined as termination of VF within 5 s post-shock. We used generalized estimating equation (GEE) analysis to assess the association between shock type (initial versus refibrillation) and shock success.

Results

Ninety-four patients presented in VF. Mean age was 65.4 years, 78.7% were male, and 80.9% were bystander-witnessed. VF recurred in 75 (79.8%). There were 338 shocks delivered for initial (n = 90) or recurrent (n = 248) VF available for analysis. Initial shocks terminated VF in 79/90 (87.8%) and subsequent shocks in 209/248 (84.3%). GEE odds ratio (OR) for shock type was 1.37 (95% CI 0.68-2.74). After adjusting for potential confounders, the OR for shock type remained insignificant (1.33, 95% CI 0.60-2.53). We observed no significant difference in ROSC (54.7% versus 52.6%, absolute difference 2.1%, p = 0.87) or neurologically intact survival to hospital discharge (21.9% versus 33.3%, absolute difference 11.4%, p = 0.31) between those with and without VF recurrence.

Conclusions

Presenting VF was terminated with one shock in 87.8% of cases. We observed no significant difference in the frequency of shock success between initial versus recurrent VF. VF recurred in the majority of patients and did not adversely affect shock success, ROSC, or survival.     

Association of the time to first epinephrine administration and outcomes in out-of-hospital cardiac arrest: SOS-KANTO 2012 study

Objective

This study assessed the association between the timing of first epinephrine administration (EA) and the neurological outcomes following out-of-hospital cardiac arrests (OHCAs) with both initial shockable and non-shockable rhythms.

Association of out-of-hospital cardiac arrest with prior activity and ambient temperature

Objective

Little is known about triggers of sudden cardiac arrest. This study aimed to analyze the association of the occurrence of out-of-hospital cardiac arrest (OHCA) with patient activities just before the arrest and ambient temperature as one of the major environmental factors.

Methods

This prospective, population-based cohort study enrolled all person aged 18 years or older with OHCA of presumed cardiac origin in Osaka Prefecture, Japan, from 2005 through 2007. Patient activities before arrest were divided into six categories: sleeping, bathing, working, exercising, non-specific activities, and unknown. Age-adjusted annual incidence rate of OHCA according to their prior activity and an hourly event rate in each activity by temperature were calculated.

Results

Among 19,303 OHCAs, 10,723 were presumed to be of cardiac etiology. The event rate of OHCA was 6.22, 54.49, 1.15, and 10.11 per 10,000,000 population per hour for sleeping, bathing, working, and exercising, respectively. Among patients who suffered OHCA during bathing, the event rate of OHCA per 10,000,000 per hour increased with decreasing temperature from 18.27 (≥25.1 °C) to 111.42 (≤5.0 °C) (odds ratio [OR] for 1 °C increase in temperature, 0.915; 95% confidence interval [CI], 0.907-0.923), while it was almost constant among those who were working (OR for 1 °C increase, 0.994; 95% CI, 0.981-1.007) or exercising (OR for 1 °C increase, 1.004; 95% CI, 0.971-1.038) before arrest.

Conclusion

Both activities before cardiac arrest and ambient temperature were associated with the occurrence of OHCA. Preventive measures against OHCA should be enveloped considering these behavioral and environmental factors.     

Prodromal symptoms and health care consumption prior to out-of-hospital cardiac arrest in patients without previously known ischaemic heart disease

Aims

To describe prodromal symptoms and health care consumption prior to an out-of-hospital cardiac arrest (OHCA) in patients without previously known ischaemic heart disease (IHD).

Background

The most common lethal event of cardiovascular disease is sudden cardiac death, and the majority occur outside hospital. Little is known about prodromal symptoms and health care consumption associated with OHCAs.

Design

Case-crossover study.

Methods

Medical records of 403 OHCA cases without previously known IHD, age 25–74 years in the MONICA myocardial registry in Norrbotten County 2000–2008, were reviewed. Presenting symptoms and emergency visits at public primary care facilities and internal medicine clinics in Norrbotten County were analyzed from the week prior to the OHCA and from the same week one year previously, which served as a control week. Unlike most studies we included unwitnessed arrests and those where no cardiopulmonary resuscitation (CPR) was attempted.

Results

Emergency visits were more common during the week prior to the OHCA than during the control week, both for visits to primary care (29 vs. 6, p < 0.001) and to internal medicine clinics (16 vs. 0, p < 0.001). Symptoms were more prevalent during the week prior to the OHCA (36.7 vs. 6.7%, p < 0.001). The most prevalent symptoms were chest pain (14.6 vs. 0%, p < 0.001), gastrointestinal symptoms (7.7 vs. 1.2%, p < 0.001) and dyspnoea/peripheral oedema (6.9 vs. 0.2%, p < 0.001).

Conclusions

Patients who suffer an OHCA seek health care and present prodromal symptoms significantly more often the week prior to the event than the same week one year earlier.     

New treatment bundles improve survival in out-of-hospital cardiac arrest patients: A historical comparison

Introduction

Before the introduction of the new international cardiac arrest treatment guidelines in 2005, patients with out-of-hospital cardiac arrest (OHCA) of cardiac origin in Northern Italy had very poor prognosis. Since 2006, a new bundle of care comprising use of automated external defibrillators (AEDs) and therapeutic hypothermia (TH) was started, while extracorporeal CPR program (ECPR) for selected refractory CA and dispatcher-assisted cardio-pulmonary resuscitation (CPR) was started in January 2010.

Objectives

We hypothesized that a program of bundled care might improve outcome of OHCA patients.

Methods

We analyzed data collected in the OHCA registry of the MB area between September 2007 and August 2011 and compared this with data from 2000 to 2003.

Results

Between 2007 and 2011, 1128 OHCAs occurred in the MB area, 745 received CPR and 461 of these had a CA of presumed cardiac origin. Of these, 125 (27%) achieved sustained ROSC, 60 (13%) survived to 1 month, of whom 51 (11%) were discharged from hospital with a good neurological outcome (CPC ≤ 2), and 9 with a poor neurological outcome (CPC > 2).Compared with data from the 2000 to 2003 periods, survival increased from 5.6% to 13.01% (p < 0.0001). In the 2007–2011 group, low-flow time and bystander CPR were independent markers of survival.

Conclusions

OHCA survival has improved in our region. An increased bystander CPR rate associated with dispatcher-assisted CPR was the most significant cause of increased survival, but duration of CA remains critical for patient outcome.     

Survival rates in out-of-hospital cardiac arrest patients transported without prehospital return of spontaneous circulation: An observational cohort study

Background

Some Emergency Medical Services currently use just one component of the Universal Termination of Resuscitation (TOR) Guideline, the absence of prehospital return of spontaneous circulation (ROSC), as the single criteria to terminate resuscitation, which may deny transport to potential survivors.

Objective

This study aimed to report the survival to hospital discharge rate in non-traumatic, adult out-of-hospital cardiac arrest (OHCA) patients transported to hospital without a prehospital ROSC.

Methods

An observational study of OHCA patients without a prehospital ROSC who met the Universal TOR Guideline for transport to hospital with ongoing resuscitation. Multivariable logistic regression was used to determine the association of each variable with survival to hospital discharge.

Results

Of 20,207 OHCA treated by EMS, 3374 (16.4%) did not have a prehospital ROSC but met the Universal TOR guideline for transport to hospital with ongoing resuscitation. Of these patients, 122 (3.6%) survived to hospital discharge. Survival to discharge was associated with initial shockable VF/VT rhythms (OR 5.07; 95% CI 2.77–9.30), EMS-witnessed arrests (OR 3.51; 95% CI 1.73–7.15), bystander-witnessed arrests (OR 2.11; 95% CI 1.18–3.77), and public locations (OR 1.57; 95% CI 1.02–2.40).

Conclusion

In OHCA patients without a prehospital ROSC who met the Universal TOR Guideline for transport with ongoing resuscitation survival rates were above the 1% futility rate. Employing only the lack of ROSC as criteria for termination of resuscitation may miss survivors after OHCA.     

Association of body weight with total mortality and with ICD shocks among survivors of ventricular fibrillation in out-of-hospital cardiac arrest

AIM: Studies have shown an association between obesity and total mortality among people with and without coronary artery disease. This study reviews outcomes among obese survivors of ventricular fibrillation in out-of-hospital cardiac arrest. METHODS: All survivors of ventricular fibrillation in out-of-hospital cardiac arrest who presented in Rochester, MN from November 1990 to September 2006 were included and classified by body weight. Implantable cardioverter defibrillator shocks administered were determined by review of subsequent device interrogations. RESULTS: Among a study population of 226, 99 (44%) survived to hospital discharge with neurological recovery. Data to calculate body mass index were available in 213 cases (95%). There was no significant difference in the relative distribution of body weight between hospital survivors and non-survivors, nor in cardioverter defibrillator implantation rates. Mean follow-up was 5.8+/-4.4 years; 5-year survival was 80+/-5%, lower among underweight and normal compared with heavier individuals. The 5-year survival free of implantable cardioverter defibrillator shocks was 61+/-7%, with no weight-based difference in shocks. CONCLUSION: There was no apparent weight-based influence on resuscitation survival after ventricular fibrillation in out-of-hospital cardiac arrest. People of normal or low weight had a lower long-term survival and represent at population high risk from primarily non-cardiac diseases.     

Improving outcome after out-of-hospital cardiac arrest by strengthening weak links of the local Chain of Survival; quality of advanced life support and post-resuscitation care

Background

Survival after out-of-hospital cardiac arrest (OHCA) depends on a well functioning Chain of Survival. We wanted to assess if targeted attempts to strengthen the weak links of our local chain; quality of advanced life support (ALS) and post-resuscitation care, would improve outcome.

Materials and methods

Utstein data from all OHCAs in Oslo during three distinct 2-year time periods 1996-1998, 2001-2003 and 2004-2005 were collected. Before the second period the local ALS guidelines changed with increased focus on good quality chest compressions with minimal pauses, while standardized post-resuscitation care including goal directed therapy with therapeutic hypothermia and percutaneous coronary intervention was added in the third period. Additional a priori sub-group analyses of arrests with cardiac aetiology as well as bystander witnessed ventricular fibrillation/tachycardia (VF/VT) arrests with cardiac aetiology were performed.

Results

ALS was attempted in 454, 449, and 417 patients with OHCA in the first, second and last time period, respectively. From the first to the third period VF/VT arrests declined (40% vs. 33%, p = 0.039) and fewer arrests were witnessed (80% vs. 72%, p = 0.022) and response intervals increased (7 ± 4 to 9 ± 4 min, p < 0.001). Overall survival increased from 7% (first period) to 13% (last period), p = 0.002, and survival in the sub-group of bystander witnessed VF/VT arrests with cardiac aetiology increased from 15% (first period) to 35% (last period), p = 0.001.

Conclusions

Survival after OHCA was increased after improving weak links of our local Chain of Survival, quality of ALS and post-resuscitation care.     

心脏缓慢性与快速性心律失常交替引起猝死的抢救

目的　研究快速性心律失常与缓慢性心律失常引起猝死的抢救。方法　 7例病人因不同疾病住院期间突发心源性猝死 ,心电监护显示猝死时心电图表现形式为快速性心律失常与缓慢性心律失常两者交替出现。应用胸前捶击及胸外按压的方法可立即终止这两种心律失常的发作 ,并最终恢复窦律 ,在抢救过程中 4例病人使用了升压药 ,1例辅助使用了人工呼吸器 ,1例使用了临时心内起搏器。结果　 7例病人全部抢救成功。结论　快速性心律失常与缓慢性心律失常引起的心源性猝死用胸前捶击及胸外按压方法抢救是有效的。     

A model of survival from out-of-hospital cardiac arrest using the Boston EMS arrest registry

Objectives

To characterize the survival rate for out-of-hospital arrests of cardiac aetiology and predictor variables associated with survival in Boston, MA, and to develop a composite multivariate logistic regression model for projecting survival rates.

Methods

This is a retrospective analysis of all arrests of presumed cardiac aetiology (from January 1, 2004 to December 31, 2007) where resuscitation was attempted (n = 1156) by 911 emergency responders.

Results

The survival-at-hospital discharge rate was 11% (vs. 1-10% often reported). The coefficients and odds ratios in the first equation of the model show that joint presence of presenting rhythm of ventricular fibrillation/tachycardia (VF/VT) and return of spontaneous circulation in the pre-hospital setting (ROSC) is a substantial direct predictor of survival (e.g., 54% of such cases survive). Response time, public location, witnessed, and age are significant but less sizable direct predictors of survival. A second equation shows that these four variables make an additional indirect contribution to survival by affecting the probability of joint presence of VF/VT and ROSC; bystander CPR also makes such an indirect contribution but no significant direct one as shown in the first equation. The projected survival rate if cases had always experienced bystander CPR and rapid response time of less than four minutes is 21%.

Conclusions

The unique model describes the major contribution of VF/VT and ROSC, and key relationships among predictors of survival. These connections may have otherwise gone underreported using standard approaches and should be considered when allocating scarce resources to impact cardiac arrest survival.     

连续胸外按压结合除颤对室颤患者的疗效观察

目的 观察连续胸外按压结合除颤对室颤猝死患者的复苏效果.方法 2005-02～2009-02室颤患者行除颤加连续胸外按压,而2001-06～2005-01收治的室颤患者行连续电除颤治疗,比较两组患者的抢救效果.结果 与连续除颤者相比,连续性胸外按压加除颤组自主循环恢复率较高;除颤次数少;入院率增加;自主循环恢复所需时间缩短.结论 连续性胸外按压结合除颤可提高室颤猝死患者的复苏成功率.