Energy doses for treatment of out-of-hospital pediatric ventricular fibrillation

AIM: To investigate the energy dose used to treat out-of-hospital pediatric ventricular fibrillation and the survival rates of these patients. METHODS: We reviewed three emergency medical systems (EMS) for their reports of patients under 1 month to 18 years who received shocks for ventricular fibrillation to determine the energy of each shock as well as other patient and care characteristics. Each patient's weight was estimated at the age-appropriate 50th and 95th percentiles. Patients were then grouped as receiving recommended energy doses (2 to < or = 4 J/kg), moderately high energy doses (> 4-6 J/kg), and high energy doses (> 6 J/kg). RESULTS: Of 57 patients identified, 54% were male, with a mean age of 11 years, range 2 months to 17 years. Ventricular fibrillation was the initial rhythm in 80% (43/54) of patients. The mean number of shocks delivered was 3, with < or = 2 shocks delivered to 28 (49%) and > or = 5 shocks delivered to 10 (18%) patients. When evaluating all 185 shocks using the 50th percentile estimated weight, 45 (24%) shocks were at recommended doses, 56 (30%) were at moderately high energy doses, and 84 (45%) were high energy doses. Elevated energy dose was associated with an increasing number of shocks and lack of bystander CPR (p < .05). Nineteen (33%) patients survived to hospital discharge having received total doses up to 73 J/kg. Energy dose was not related to survival. CONCLUSION: In this observational, multicenter out of hospital experience, children received a wide range of defibrillation doses, often exceeding recommended doses and equivalent to adult energy levels. Survival occurred at low and very high energy doses.     

Double sequential defibrillation for refractory ventricular fibrillation

A 54-year-old suffered from an out-of-hospital cardiac arrest. Compressions were started within minutes and the patient was in refractory ventricular fibrillation despite multiple asynchronized shocks and maximal doses of antiarrhythmic agents. Double sequential defibrillation was attempted with successful Return Of Spontaneous Circulation (ROSC) after a total of 61 min of cardiac arrest. The patient was discharged home neurologically intact. Double sequential defibrillation could be a simple effective approach to patients with refractory ventricular fibrillation.     

扩张型心肌病室速和室颤的抢救治疗及随访

目的　探讨应用胺碘酮 (AM)对扩张型心肌病 (DCM)伴室性心动过速 (VT)和 (或 )心室颤动 (VF)的治疗及预防疗效。方法　本组 19例 DCM伴 VT和 (或 ) VF,左室射血分数 (L VEF) (2 3± 8.2 ) % ,静脉注射 AM首剂 3～ 5 mg/kg,稀释后 10～ 2 0分钟注入 ,继以 0 .75～ 1mg/min维持静脉注射 ,如心律失常控制不满意 ,可每隔 30分钟追加 75～ 15 0 mg的 AM。在静脉用药的同时口服 AM6 0 0～ 80 0 mg/d。结果　 11/19患者 2 4小时心律失常获控制占 5 8% ,AM静脉用量平均为 (12 41± 12 5 .5 ) mg(115 6～ 2 14 2 mg) ,72小时完全控制心律失常。结论　静脉注射 AM治疗 DCM并 VT和 (或 ) VF安全有效 ,预防心律失常发作需长期口服 AM。     

急性心肌梗死并室性心动过速/心室颤动的影响因素分析

目的:分析急性心肌梗死(acute myocardial infarction,AMI)患者并发室性心动过速(ventricular tachycardia,VT)/心室颤动(ventricular fibrillation,VF)的影响因素.方法:将安徽医科大学第一附属医院收治的453例AMI患者分为VT/VF组和无VT/VF组,对两组进行比较分析发生VT/VF的影响因素.结果:单因素分析示,VT/VF组与无VT/VF组在诸多方面差异有显著性.经多因素Logistic回归分析显示,高级别的Killip分级、血钾离子水平异常以及广泛前壁心肌梗死是影响患者发生VT/VF的独立危险因素,β-受体阻滞剂是保护因素.结论:VT/VF是AMI患者的严重并发症,高级别的Killip分级、血钾水平异常以及广泛前壁心肌梗死是影响患者发生VT/VF的独立危险因素,而β-受体阻滞剂是保护因素.     

Detrended fluctuation analysis predicts successful defibrillation for out-of-hospital ventricular fibrillation cardiac arrest

Aims

Repeated failed shocks for ventricular fibrillation (VF) in out-of-hospital cardiac arrest (OOHCA) can worsen the outcome. It is very important to rapidly distinguish between early and late VF. We hypothesised that VF waveform analysis based on detrended fluctuation analysis (DFA) can help predict successful defibrillation.

Methods

Electrocardiogram (ECG) recordings of VF signals from automated external defibrillators (AEDs) were obtained for subjects with OOHCA in Taipei city. To examine the time effect on DFA, we also analysed VF signals in subjects who experienced sudden cardiac death during Holter study from PhysioNet, a publicly accessible database. Waveform parameters including root-mean-squared (RMS) amplitude, mean amplitude, amplitude spectrum analysis (AMSA), frequency analysis as well as fractal measurements including scaling exponent (SE) and DFA were calculated. A defibrillation was regarded as successful when VF was converted to an organised rhythm within 5 s after each defibrillation.

Results

A total of 155 OOHCA subjects (37 successful and 118 unsuccessful defibrillations) with VF were included for analysis. Among the VF waveform parameters, only AMSA (7.61 ± 3.30 vs. 6.30 ± 3.13, P = 0.028) and DFAα2 (0.38 ± 0.24 vs. 0.49 ± 0.24, P = 0.013) showed significant difference between subjects with successful and unsuccessful defibrillation. The area under the curves (AUCs) for AMSA and DFAα2 was 0.63 (95% confidence interval (CI) = 0.52-0.73) and 0.65 (95% CI = 0.54-0.75), respectively. Among the waveform parameters, only DFAα2, SE and dominant frequency showed significant time effect.

Conclusions

The VF waveform analysis based on DFA could help predict first-shock defibrillation success in patients with OOHCA. The clinical utility of the approach deserves further investigation.     

A phased approach to cardiac arrest resuscitation involving ventricular fibrillation and pulseless ventricular tachycardia

With the release of the 2010 American Heart Association (AHA) Guidelines for cardiopulmonary resuscitation and emergency cardiac care, evidence regarding management of out-of-hospital cardiac arrest suggests a more fundamental approach. To aid in understanding and learning, this article proposes a method that optimizes the timing and delivery of evidence-proven therapies with a 3-phase approach for out-of-hospital resuscitation from ventricular fibrillation and pulseless ventricular tachycardia. Although this model is not a new concept, it is largely based on the 2010 AHA Guidelines, enhancing the philosophy of the "CAB" concept (Chest compressions/Airway management/Breathing rescue).     

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.     

Incidence and outcomes of out-of-hospital cardiac arrest with shock-resistant ventricular fibrillation: Data from a large population-based cohort

Background

The increasing survival rates after out-of-hospital cardiac arrests (OHCA) are due mainly to improvements in the first 3 steps of the chain of survival. The aim of this study was to describe the temporal trends of OHCA incidence and outcomes with shock-resistant ventricular fibrillation (VF) requiring advanced life support procedures.

Methods

All our subjects were persons aged 18 years or more who had suffered OHCA of presumed cardiac etiology, were witnessed by bystanders, treated by emergency medical service (EMS), and had VF as initial rhythm. Our study was conducted in Osaka Prefecture, Japan from May 1, 1998 through December 31, 2006. Data were collected by EMS personnel using an Utstein-style database. We evaluated the temporal trends of incidence and outcomes of shock-resistant VF.

Results

During the study period, there were 8782 witnessed OHCA cases of presumed cardiac etiology. Among them, 1733 had VF as an initial rhythm, 392 of whom were shock-resistant. While the age-adjusted annual incidence of witnessed VF increased from 2.0 to 3.3 per 100,000 inhabitants, that of shock-resistant VF underwent little change during the study period. The proportion of shock-resistant VF among witnessed VF decreased from 37.0% to 19.0%. Neurologically intact 1-month survival rates after shock-resistant VF remained low at 5.6% even in 2006.

Conclusion

The actual incidence of shock-resistant VF has remained unchanged, and their outcomes continue to be dismal. Further efforts are required to reduce the mortality rates of such shock-resistant VF to achieve improved survival after OHCA.     

Transthoracic defibrillation potential gradients in a closed chest porcine model of prolonged spontaneous and electrically induced ventricular fibrillation

Objective

The purpose of this study was to measure the local electrical field or potential gradient, measured with a catheter-based system, required to terminate long duration electrically or ischaemically induced ventricular fibrillation (VF). We hypothesized that prolonged ischaemic VF would be more difficult to terminate when compared to electrically induced VF of similar duration.

Methods

Thirty anesthetized and instrumented swine were randomized to electrically induced VF or spontaneous, ischaemically induced VF, produced by balloon occlusion of the left anterior descending coronary artery. After 7 min of VF, chest compressions were initiated and rescue shocks were attempted 1 min later. The potential gradient for each shock was measured and the mean values required for defibrillation compared for the VF groups.

Results

The number of shocks and the shock strength required for termination of VF were not significantly different for the groups. The potential gradient of the first successful defibrillating shock was significantly greater in the spontaneous, occlusion-induced VF group (12.80 ± 2.82 V/cm vs 9.60 ± 2.48 V/cm, p = 0.002). The number of refibrillations was greater in the ischaemic group than in the non-ischaemic electrical group (6 ± 4 vs 1 ± 1, p < 0.001). The number of animals requiring a shock at 360 J was 2.5 times greater for the ischaemic group.

Conclusions

Defibrillation of prolonged VF produced by acute myocardial ischaemia requires a significantly greater potential gradient to terminate than prolonged VF induced by electrical stimulation of the right ventricular endocardium. The VF duration used in this study approximates that occurring in victims of out-of-hospital cardiac arrest. Our findings may be of clinical importance in the management of such patients.     

长时程室颤先行心肺复苏对复苏效果的影响及机制研究

目的 比较7 min室颤先行心肺复苏2 min后除颤与直接除颤的复苏效果,并探讨其机制.方法 建立猪闭胸电诱发室颤模型,CPR First组优先心肺复苏2 min后连续三次除颤,Shock First组直接予连续三次除颤,观察冠脉灌注压、室颤波频率和振幅变化,计算除颤成功率和自主循环恢复率.结果 CPR First组先行心肺复苏2 min后可提高初次除颤前的冠脉灌注压、室颤波的频率和振幅, CPR First组比Shock First组有高的除颤成功率和自主循环恢复率(P＜0.05).结论 7 min室颤除颤前先行胸外按压和人工呼吸可明显提高复苏成功率,其机制与增加冠脉灌注,改善心脏能量储备,提高室颤波的频率和振幅有关.     

Acoustic cardiographic recording during ventricular fibrillation

This is the second case report in literature that describes the simultaneous acoustic cardiographic, electrocardiographic, and invasive hemodynamic events that occurred before, during and after ventricular fibrillation that was successfully cardioverted to sinus rhythm. The absence of heart sounds, which are linked to the lack of effective myocardial contractility, correlated well with invasive hemodynamic data, indicating the lack of perfusion during ventricular fibrillation. These observations, coupled with the challenges of pulse detection as a sign of adequate perfusion during resuscitation suggest that acoustic cardiography may be a potentially effective supplemental diagnostic tool during the resuscitation of malignant arrhythmias.     

胺碘酮原液和稀释液对心室颤动转复作用及血流动力学的影响

目的 通过猪心室颤动(VF)模型,观察胺碘酮原液、稀释液以及单纯标准CPR对心肺复苏效果的影响.方法 21头北京长白猪,应用程控刺激仪诱导VF,VF 3 min后,将动物随机(随机数字法)分为3组.①单纯CPR组:只进行单纯标准CPR;②胺碘酮原液组:予胺碘酮原液5 mg/kg快速(＜3 s)静推,生理盐水20 mL冲管,观察30 s后开始CPR;③胺碘酮稀释液组:予胺碘酮5 mg/mg溶于20 mL生理盐水用30 s缓慢静推,20 mL生理盐水冲管,观察30 s后开始CPR.VF 5 min若猪未恢复自主循环(ROSC),给予电击除颤,并再次给予CPR,依此类推如15 min后猪仍未ROSC则宣布猪死亡.结果 CPR组及胺碘酮原液组复苏成功率高于胺碘酮稀释液组[85.7%vs.71.4%vs.42.9%],但差异均无统计学意义(P＞0.05).标准CPR组除颤能量(450±150)J高于胺碘酮原液组(200±77)J(P=0.009)及稀释液组(330±125)J,P=0.170.标准CPR组除颤次数(3±1)多于胺碘酮原液组(1.3±0.5),P＜0.05.ROSC 10 min时胺碘酮原液组的平均动脉压(MAP)和冠脉灌注压(CPP)明显低于稀释液组和CPR组(P＜0.05),而ROSC 0.5 h以后胺碘酮原液组和稀释液组之间MAP和CPP差异无统计学意义(P＞0.05).结论 心肺复苏时应用胺碘酮原液可以减少除颤次数和能量;较标准CPR和快速推注胺碘酮原液,胺碘酮稀释液缓慢推注有增加死亡率的可能.     

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.     

Amplitude spectrum area to guide resuscitation—A retrospective analysis during out-of-hospital cardiopulmonary resuscitation in 609 patients with ventricular fibrillation cardiac arrest

Introduction

The capability of amplitude spectrum area (AMSA) to predict the success of defibrillation (DF) was retrospectively evaluated in a large database of out-of-hospital cardiac arrests.

Methods

Electrocardiographic data, including 1260 DFs, were obtained from 609 cardiac arrest patients due to ventricular fibrillation. AMSA sensitivity, specificity, accuracy, and positive and negative predictive values (PPV, NPV) for predicting DF success were calculated, together with receiver operating characteristic (ROC) curves. Successful DF was defined as the presence of spontaneous rhythm ≥40 bpm starting within 60 s from the DF. In 303 patients with chest compression (CC) depth data collected with an accelerometer, changes in AMSA were analyzed in relationship to CC depth.

Results

AMSA was significantly higher prior to a successful DF than prior to an unsuccessful DF (15.6 ± 0.6 vs. 7.97 ± 0.2 mV-Hz, p < 0.0001). Intersection of sensitivity, specificity and accuracy curves identified a threshold AMSA of 10 mV-Hz to predict DF success with a balanced sensitivity, specificity and accuracy of almost 80%. Higher AMSA thresholds were associated with further increases in accuracy, specificity and PPV. AMSA of 17 mV-Hz predicted DF success in two third of instances (PPV of 67%). Low AMSA, instead, predicted unsuccessful DFs with high sensitivity and NPV >97%. Area under the ROC curve was 0.84. CC depth affected AMSA value. When depth was <1.75 in., AMSA decreased for consecutive DFs, while it increased when the depth was >1.75 in. (p < 0.05).

Conclusions

AMSA could be a useful tool to guide CPR interventions and predict the optimal timing of DF.     

New strategies for ventricular tachycardia and ventricular fibrillation ablation

Patients with ventricular tachycardia (VT) and ventricular fibrillation (VF) and no reversible cause are difficult to treat. While implantable defibrillators prolong survival, many patients remain symptomatic due to device shocks and syncope. To address this, there have been recent advances in the catheter ablation of VT and VF. For example, non-invasive imaging has improved arrhythmia substrate characterisation, 3D catheter navigation tools have facilitated mapping of arrhythmia and substrate and ablation catheters have advanced in their ability to deliver effective lesions. However, the long-term success rates of ablation for VT and VF remain modest, with nearly half of treated patients developing recurrence within 2–3 years, and this drives the ongoing innovation in the field. This review focuses on the challenges particular to ablation of life-threatening ventricular arrhythmia, and the strategies that have been recently developed to improve procedural efficacy. Patient sub-groups that illustrate the use of new strategies are described.     

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.     

Atrial fibrillation and recurrent ventricular fibrillation during hypokalemia in Brugada syndrome

A 41-year-old man with Brugada syndrome (BS) and no previous episodes of aborted sudden death or syncope referred to local emergency room for an episode of symptomatic atrial fibrillation. Blood chemistry results showed hypokalemia (2.9 mEq/L). The other parameters were within the normal range. After few minutes, an episode of ventricular fibrillation treated with biphasic DC shock 150 J occurred. In successive 2 hours, the patient experienced recurrent episodes of ventricular tachycardia and fibrillation. Each biphasic DC shock 150 J was effective to restore sinus rhythm. No further episodes occurred after normalization of serum levels of potassium. Before discharge, an implantable cardioverter defibrillator was inserted to prevent sudden cardiac death. Hypokalemia increases the risk of arrhythmic events in BS.