BIPHASIC Trial

Recurrence of ventricular fibrillation in out-of-hospital cardiac arrest: Clinical evidence and underlying ionic mechanisms

Defibrillation remains the optimal therapy for terminating ventricular fibrillation (VF) in out-of-hospital cardiac arrest (OHCA) patients, with reported shock success rates of ∼90%. A key persistent challenge, however, is the high rate of VF recurrence (∼50-80%) seen during post-shock cardiopulmonary resuscitation (CPR). Studies have shown that the incidence and time spent in recurrent VF are negatively associated with neurologically-intact survival. Recurrent VF also results in the administration of extra shocks at escalating energy levels, which can cause cardiac dysfunction. Unfortunately, the mechanisms underlying recurrent VF remain poorly understood. In particular, the role of chest-compressions (CC) administered during CPR in mediating recurrent VF remains controversial. In this review, we first summarize the available clinical evidence for refibrillation occurring during CPR in OHCA patients, including the postulated contribution of CC and non-CC related pathways. Next, we examine experimental studies highlighting how CC can re-induce VF via direct mechano-electric feedback. We postulate the ionic mechanisms involved by comparison with similar phenomena seen in commotio cordis. Subsequently, the hypothesized contribution of partial cardiac reperfusion (either as a result of CC or CC independent organized rhythm) in re-initiating VF in a globally ischaemic heart is examined. An overview of the proposed ionic mechanisms contributing to VF recurrence in OHCA during CPR from a cellular level to the whole heart is outlined. Possible therapeutic implications of the proposed mechanistic theories for VF recurrence in OHCA are briefly discussed.

2024 RECOVER Guidelines: Advanced Life Support. Evidence and knowledge gap analysis with treatment recommendations for small animal CPR

OBJECTIVE

To systematically review the evidence and devise clinical recommendations on advanced life support (ALS) in dogs and cats and to identify critical knowledge gaps.

DESIGN

Standardized, systematic evaluation of literature pertinent to ALS following Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology. Prioritized questions were each reviewed by Evidence Evaluators, and findings were reconciled by ALS Domain Chairs and Reassessment Campaign on Veterinary Resuscitation (RECOVER) Co-Chairs to arrive at treatment recommendations commensurate to quality of evidence, risk:benefit relationship, and clinical feasibility. This process was implemented using an Evidence Profile Worksheet for each question that included an introduction, consensus on science, treatment recommendations, justification for these recommendations, and important knowledge gaps. A draft of these worksheets was distributed to veterinary professionals for comment for 4 weeks prior to finalization.

SETTING

Transdisciplinary, international collaboration in university, specialty, and emergency practice.

RESULTS

Seventeen questions pertaining to vascular access, vasopressors in shockable and nonshockable rhythms, anticholinergics, defibrillation, antiarrhythmics, and adjunct drug therapy as well as open-chest CPR were reviewed. Of the 33 treatment recommendations formulated, 6 recommendations addressed the management of patients with nonshockable arrest rhythms, 10 addressed shockable rhythms, and 6 provided guidance on open-chest CPR. We recommend against high-dose epinephrine even after prolonged CPR and suggest that atropine, when indicated, is used only once. In animals with a shockable rhythm in which initial defibrillation was unsuccessful, we recommend doubling the defibrillator dose once and suggest vasopressin (or epinephrine if vasopressin is not available), esmolol, lidocaine in dogs, and/or amiodarone in cats.

CONCLUSIONS

These updated RECOVER ALS guidelines clarify the approach to refractory shockable rhythms and prolonged CPR. Very low quality of evidence due to absence of clinical data in dogs and cats continues to compromise the certainty with which recommendations can be made.

The impact of alternate defibrillation strategies on shock-refractory and recurrent ventricular fibrillation: A secondary analysis of the DOSE VF cluster randomized controlled trial

BACKGROUND

The DOSE VF randomized controlled trial (RCT) employed a pragmatic definition of refractory ventricular fibrillation (VF after three successive shocks). However, it remains unclear whether the underlying rhythm during the first three shocks was shock-refractory or recurrent VF.

OBJECTIVE

To explore the relationship between alternate defibrillation strategies employed during the DOSE VF RCT and the type of VF, either shock-refractory VF or recurrent VF, on patient outcomes.

METHODS

We performed a secondary analysis of the DOSE VF RCT. We categorized cases as shock-refractory or recurrent VF based on pre-randomization shocks (shocks 1-3). We then analyzed all subsequent (post-randomization) shocks to assess the impact of standard, vector change (VC) or double sequential external defibrillation (DSED) shocks on clinical outcomes employing logistic regression adjusted for Utstein variables, antiarrhythmics, and epinephrine.

RESULTS

We included 345 patients; 60 (17%) shock-refractory VF, and 285 (83%) recurrent VF. Patients in recurrent VF had greater survival than shock-refractory VF (OR: 2.76 95% CI [1.04, 7.27]). DSED was superior to standard defibrillation for survival overall, and for patients with shock-refractory VF (28.6% vs 0%, p = 0.041) but not for those in recurrent VF. DSED was superior to standard defibrillation for return of spontaneous circulation (ROSC) and neurologic survival for shock-refractory and recurrent VF. VC defibrillation was not superior for survival or ROSC overall, for shock-refractory, or recurrent VF groups, but was superior for VF termination across all groups.

CONCLUSION

DSED appears to be the superior defibrillation strategy in the DOSE VF trial, irrespective of whether the preceding VF is shock-refractory or recurrent.

Amplitude spectral area of ventricular fibrillation and defibrillation success at low energy in out-of-hospital cardiac arrest

The optimal energy for defibrillation has not yet been identified and very often the maximum energy is delivered. We sought to assess whether amplitude spectral area (AMSA) of ventricular fibrillation (VF) could predict low energy level defibrillation success in out-of-hospital cardiac arrest (OHCA) patients. This is a multicentre international study based on retrospective analysis of prospectively collected data. We included all OHCAs with at least one manual defibrillation. AMSA values were calculated by analyzing the data collected by the monitors/defibrillators used in the field (Corpuls 3 and Lifepak 12/15) and using a 2-s-pre-shock electrocardiogram interval. We run two different analyses dividing the shocks into three tertiles (T1, T2, T3) based on AMSA values. 629 OHCAs were included and 2095 shocks delivered (energy ranging from 100 to 360 J; median 200 J). Both in the "extremes analysis" and in the "by site analysis", the AMSA values of the effective shocks at low energy were significantly higher than those at high energy (p = 0.01). The likelihood of shock success increased significantly from the lowest to the highest tertile. After correction for age, call to shock time, use of mechanical CPR, presence of bystander CPR, sex and energy level, high AMSA value was directly associated with the probability of shock success [T2 vs T1 OR 3.8 (95% CI 2.5-6) p < 0.001; T3 vs T1 OR 12.7 (95% CI 8.2-19.2), p < 0.001]. AMSA values are associated with the probability of low-energy shock success so that they could guide energy optimization in shockable cardiac arrest patients.

Defibrillation in the Cardiac Arrest Patient

Defibrillation is one of the few interventions known to favorably impact survival in cardiac arrest. In witnessed arrest, survival improves with defibrillation as early as possible, whereas it may improve outcomes to administer high-quality chest compressions for 90 seconds before defibrillation in unwitnessed arrest. Minimizing pre-, peri-, and post-shock pauses has been shown to have mortality benefits. Refractory ventricular fibrillation has high mortality rates, and there is ongoing research into promising adjunctive treatment modalities. There remains no consensus on optimal pad positioning and defibrillation energy level, however, recent data suggest anteroposterior pad placement may be superior to anterolateral placement.

Electrical Stimulation for Low-Energy Termination of Cardiac Arrhythmias: a Review

Cardiac arrhythmias are a leading cause of morbidity and mortality in the developed world, estimated to be responsible for hundreds of thousands of deaths annually. Our understanding of the electrophysiological mechanisms of such arrhythmias has grown since they were formally characterized in the late nineteenth century, and this has led to the development of numerous devices and therapies that have markedly improved outcomes for patients affected by such conditions. Despite these advancements, the application of a single large shock remains the clinical standard for treating deadly tachyarrhythmias. Such defibrillating shocks are undoubtedly effective in terminating such arrhythmias; however, they are applied without forewarning, contributing to the patient's stress and anxiety; they can be intensely painful; and they can have adverse psychological and physiological effects on patients. In recent years, there has been interest in developing defibrillation protocols that can terminate arrhythmias without crossing the human pain threshold for energy delivery, generally estimated to be between 0.1 and 1 J. In this article, we review existing literature on the development of such low-energy defibrillation methods and their underlying mechanisms, in an attempt to broadly describe the current landscape of these technologies.

Protocol for a cluster randomised controlled feasibility study of Prehospital Optimal Shock Energy for Defibrillation (POSED)

Aims

The Prehospital Optimal Shock Energy for Defibrillation (POSED) study will assess the feasibility of conducting a cluster randomised controlled study of clinical effectiveness in UK ambulance services to identify the optimal shock energy for defibrillation.

Methods

POSED is a pragmatic, allocation concealed, open label, cluster randomised, controlled feasibility study. Defibrillators within a single UK ambulance service will be randomised in an equal ratio to deliver one of three shock strategies 120-150-200 J, 150-200-200 J, 200-200-200 J. Consecutive adults (≥18 years) presenting with out of hospital cardiac arrest requiring defibrillation will be eligible. The study plans to enrol 90 patients (30 in each group). Patients (or their relatives for non-survivors) will be informed about trial participation after the initial emergency has resolved. Survivors will be invited to consent to participate in follow-up (i.e., at 30 days or discharge).The primary feasibility outcome is the proportion of eligible patients who receive the randomised study intervention. Secondary feasibility outcomes will include recruitment rate, adherence to allocated treatment and data completeness. Clinical outcomes will include Return of an Organised Rhythm (ROOR) at 2 minutes post-shock, refibrillation rate, Return of Spontaneous Circulation (ROSC) at hospital handover, survival and neurological outcome at 30 days.

Conclusion

The POSED study will assess the feasibility of a large-scale trial and explore opportunities to optimise the trial protocol.Trial registration: ISRCTN16327029.

Septic Shock and Cardiac Arrest in Obstetrics: A Practical Simplified Clinical View

Septic shock and cardiac arrest during pregnancy, despite being uncommon, carry a high mortality rate among pregnant individuals. Basic initial management strategies are fundamental to improve clinical outcomes; obstetricians and maternal-fetal medicine specialists need to be familiar with such interventions.

Effectiveness of alternative shock strategies for out-of-hospital cardiac arrest: A systematic review

Aim

To determine the optimal first-shock energy level for biphasic defibrillation and whether fixed or escalating protocols for subsequent shocks are most effective.

Methods

We searched Medline, Embase, Cochrane CENTRAL, CINAHL, the Web of Science and national and international trial registry databases for papers published from database inception to January 2022. We reviewed reference lists of key papers to identify additional references. The population included adults sustaining non traumatic out-of-hospital cardiac arrest subject to attempted defibrillation. Studies of internal or monophasic defibrillation and studies other than randomised controlled trials or prospective cohorts were excluded. Two reviewers assessed study relevance. Data extraction and risk of bias assessment, using the ROBINS-I tool, were conducted by one reviewer and checked by a second reviewer. Data underwent intention-to-treat analysis.

Results

We identified no studies evaluating first shock energy. Only one study (n = 738) comparing fixed versus escalating energy met eligibility criteria: a prospective cohort analysis of a randomised controlled trial of manual versus mechanical CPR. High fixed (360 J) energy was compared with an escalating (200-200/300-360 J) strategy. Researchers found 27.5% (70/255) of patients in the escalating energy group and 27.61% (132/478) in the fixed high energy group survived to hospital discharge (unadjusted risk ratio 0.99, 95% CI 0.73, 1.23). Results were of very low certainty as the study was at serious risk of bias.

Conclusion

This systematic review did not identify an optimal first-shock energy for biphasic defibrillation. We identified no survival advantage at 30 days when comparing 360 J fixed with 200 J escalating strategy.

Current and investigational therapies for the treatment of refractory ventricular fibrillation

DISCLAIMER

In an effort to expedite the publication of articles related to the COVID-19 pandemic, AJHP is posting these manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time.

PURPOSE

Esmolol, dual sequential defibrillation, vector change defibrillation, and left stellate ganglion block are presented and reviewed for the treatment of refractory ventricular fibrillation.

SUMMARY

Although no formal definition has been established for refractory ventricular fibrillation, the literature describes it as a pulseless ventricular arrhythmia that persists despite 3 standard defibrillation attempts, administration of amiodarone 300 mg intravenously, and provision of three 1-mg intravenous doses of epinephrine. Evolving literature surrounding resuscitation in this particular subset of cardiac arrest challenges the efficacy of traditional therapies, such as epinephrine, and suggests that other treatment modalities may improve outcomes. Case reports, case series, and small retrospective studies have pointed to benefit when utilizing a variety of therapies, namely, esmolol, dual sequential defibrillation, vector change defibrillation, or left stellate ganglion block, in patients with refractory ventricular fibrillation arrest.

CONCLUSION

A mounting, although limited, body of evidence suggests that esmolol, dual sequential defibrillation, vector change defibrillation, or left stellate ganglion block may be effective at terminating refractory ventricular fibrillation and improving patient outcomes. Further evidence is required before these therapies can be adopted as standard practice; however, as key members of the code response team, it is imperative for pharmacists to be familiar with the supporting evidence, safety considerations, and logistical challenges of utilizing these treatments during arrest.

[Adult advanced life support]

These European Resuscitation Council Advanced Life Support guidelines are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. This section provides guidelines on the prevention of and ALS treatments for both in-hospital cardiac arrest and out-of-hospital cardiac arrest.

Ventricular Fibrillation Recurrences in Successfully Shocked Out-of-Hospital Cardiac Arrests

Background and Objectives: The prognostic impact of ventricular fibrillation (VF) recurrences after a successful shock in out-of-hospital cardiac arrest (OOHCA) is still poorly understood, and some evidence suggests a potential pro-arrhythmic effect of chest compressions in this setting. In the present analysis, we looked at the short-term and long-term prognosis of VF recurrences in OOHCA. And their potential association with chest compressions. Materials and Methods: The Progetto Vita, prospectively collecting data on all resuscitation efforts in the Piacenza province (Italy), was used for the present analysis. From the 461 OOHCAs found in a shockable rhythm, only those with optimal ECG tracings and good audio recordings (160) were assessed. Rhythms other than VF post-shock were analyzed five seconds after shock delivery and survival to hospital admission, hospital discharge, and long-term survival data over a 14-year follow-up were collected. Results: Population mean age was 64.4 ± 16.9 years, and 31.9% of all patients were female. Mean time to EMS arrival was 5.9 ± 4.5 min. Short- and long-term survival without neurological impairment were higher in patients without VF recurrence when compared to patients with VF recurrence, independently from the pre-induction rhythm (p < 0.001). After shock delivery, VF recurrence was higher when chest compressions were resumed early after discharge and more vigorously. Conclusions: VF recurrences after a shock could worsen short and long-term survival. The potential pro-arrhythmic effect of chest compressions should be factored in when considering the real risks and benefits of this procedure.

European Resuscitation Council Guidelines 2021: Adult advanced life support

These European Resuscitation Council Advanced Life Support guidelines, are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. This section provides guidelines on the prevention of and ALS treatments for both in-hospital cardiac arrest and out-of-hospital cardiac arrest.

Cardiac Mechano-Electric Coupling: Acute Effects of Mechanical Stimulation on Heart Rate and Rhythm

The heart is vital for biological function in almost all chordates, including humans. It beats continually throughout our life, supplying the body with oxygen and nutrients while removing waste products. If it stops, so does life. The heartbeat involves precise coordination of the activity of billions of individual cells, as well as their swift and well-coordinated adaption to changes in physiological demand. Much of the vital control of cardiac function occurs at the level of individual cardiac muscle cells, including acute beat-by-beat feedback from the local mechanical environment to electrical activity (as opposed to longer term changes in gene expression and functional or structural remodeling). This process is known as mechano-electric coupling (MEC). In the current review, we present evidence for, and implications of, MEC in health and disease in human; summarize our understanding of MEC effects gained from whole animal, organ, tissue, and cell studies; identify potential molecular mediators of MEC responses; and demonstrate the power of computational modeling in developing a more comprehensive understanding of ‟what makes the heart tick.ˮ.

Double sequential defibrillation for out-of-hospital refractory ventricular fibrillation: A scoping review

BACKGROUND

Double sequential defibrillation (DSD) has been proposed as a viable treatment option for patients in refractory ventricular fibrillation/pulseless ventricular tachycardia (VF/pVT) out-of-hospital cardiac arrests (OHCA). However, currently there is insufficient evidence to support a widespread implementation of this therapy.

STUDY OBJECTIVES

The aim of this scoping review was to summarize the current available evidence of DSD for patients with refractory VF/pVT OHCA as well as to identify gaps in the literature that may require further research.

METHODS

We conducted a comprehensive literature search of MEDLINE via PubMed, Embase via Ovid, and Scopus on August 19, 2019. We also checked reference lists of relevant papers to identify additional studies. Any controlled clinical study design (randomized controlled trials and non-randomized controlled trials), and observational studies (cohort studies and case-control studies) providing information on resuscitative parameters, survival rates and neurological outcomes in adults (≥ 18 years old) treated with DSD for refractory VF/pVT OHCA were included. Two investigators independently conducted the literature search, study selection, and data extraction.

RESULTS

The search yielded 1612 unique records, of which 4 peer-reviewed articles were found relating to the research purpose, totaling 1061 patients of who 20.5% (n = 217) received DSD. Most studies evaluated if pre-hospital DSD was associated with improved survival to discharge after refractory VF/pVT. No randomized controlled trials were identified.

CONCLUSION

To date, it is difficult to conclude the real benefit of DSD for patients in refractory VF based on the available evidence. The findings of this scoping review suggest there is limited evidence to support at large-scale the use of DSD for refractory VF/pVT OHCA. Further research is needed to better characterize and understand the use of DSD for refractory VF/pVT, in order to implement best practices to maximize the effectiveness and efficiency of care.

Triple-sequential defibrillation for refractory ventricular fibrillation in a 24-year-old male out of hospital cardiac arrest

Refractory ventricular fibrillation encountered during cardiac arrest has a mortality rate of 97%.1 As per the advanced cardiac life support (ACLS) guidelines, the management algorithm of ventricular fibrillation consists of chest compressions, epinephrine, defibrillation, and anti-arrhythmics.2 There have been reports describing the use of the fast-acting selective β-blocker, esmolol, and dual-sequential defibrillation in the management of ventricular fibrillation that is refractory to standard ACLS. We present a case of a 24-year-old male who had an out-of-hospital cardiac arrest, with refractory ventricular fibrillation despite high-quality cardiopulmonary resuscitation (CPR) and ACLS management. Along with standard ACLS, triple-sequential defibrillation was used to achieve return of spontaneous circulation (ROSC) after 82 minutes of downtime. An electrocardiogram (ECG) after ROSC showed an ST-elevation myocardial infarction (MI), and the patient underwent angiography showing a 100% occlusion of his left anterior descending artery. Following management of his coronary artery disease, he was discharged from the hospital 16 days later and was neurologically intact.

Survival to hospital discharge with biphasic fixed 360 joules versus 200 escalating to 360 joules defibrillation strategies in out-of-hospital cardiac arrest of presumed cardiac etiology

INTRODUCTION

Guidelines recommend constant or escalating energy levels for shocks after the initial defibrillation attempt. Studies comparing survival to hospital discharge with escalating vs fixed high energy level shocks are lacking. We compared survival to hospital discharge for 200 J escalating to 360 J vs fixed 360 J in patients with initial ventricular fibrillation/pulseless ventricular tachycardia in a post-hoc analysis of the Circulation Improving Resuscitation Care trial database.

METHODS AND RESULTS

Pre-shock rhythm, rhythm 5 s after shock, shock energy levels, termination of ventricular fibrillation/pulseless ventricular tachycardia (TOF), and survival to hospital discharge were recorded. Association between defibrillation strategy and survival to hospital discharge was investigated with multivariable logistic regression. The escalating energy group included 260 patients and 883 shocks vs 478 patients and 1736 shocks in the fixed-high energy group. There was no difference in survival to hospital discharge between escalating (70/255 patients, 28%) and fixed energy group (132/478 patients, 28%) (unadjusted OR 1.00, 95% CI 0.72-1.42 and adjusted OR 0.81, 95% CI 0.54-1.22, p = 0.32). First shock TOF was 86% in the escalating group compared to 83% in the fixed-high group, p = 0.27.

CONCLUSION

There was no difference in survival to hospital discharge or the frequency of TOF between escalating energy and fixed-high energy group. ClinicalTrials.gov Identifier: NCT00597207.

Evolving Strategies in Cardiac Arrest Management

Cardiac arrest is a leading cause of death in the United States, with a hospital discharge rate of approximately 10%. International resuscitation guidelines offer standardized cardiac arrest management approaches, but beyond the guidelines, are promising innovations to improve resuscitative care. Although clinical data do not yet support the routine use of mechanical chest compressions, corticosteroids, thrombolytics, and adjunctive ventilation devices during arrest, these therapies may have an important role in select patients. Extracorporeal membrane oxygenation during cardiopulmonary resuscitation is a promising advancement and may have survival benefit in select patients. The evidence for standard therapies and these innovations is discussed.

Singapore Defibrillation Guidelines 2016

The most common initial rhythm in a sudden cardiac arrest is ventricular fibrillation or pulseless ventricular tachycardia. This is potentially treatable with defibrillation, especially if provided early. However, any delay in defibrillation will result in a decline in survival. Defibrillation requires coordination with the cardiopulmonary resuscitation component for effective resuscitation. These two components, which form the key links in the chain of survival, have to be brought to the cardiac victim in a timely fashion. An effective chain of survival is needed in both the institution and community settings.

Interaction of defibrillation waveform with the time to defibrillation or the number of defibrillation attempts on survival from out-of-hospital cardiac arrest

AIM

Early biphasic defibrillation is effective in out-of-hospital cardiac arrest (OHCA) cases. In the resuscitation of patients with OHCA, it is not clear how the defibrillation waveform interacts with the time to defibrillation to influence patient survival. The second, and any subsequent, shocks need to be administered by an on-line physician in Japan. Thus, we investigated the interaction between the defibrillation waveform and time to or the number of defibrillation on resuscitation outcomes.

METHODS

This prospective observational study used data for all OHCAs that occurred between 2005 and 2014 in Japan. To investigate the interaction effect between the defibrillation waveform and the time to defibrillation or the number of defibrillations on the return to spontaneous circulation (ROSC), 1-month survival, and cerebral performance category (CPC) (1, 2), we assessed the modifying effects of the defibrillation waveform and the time to or the number of defibrillation on additive scale (i.e., the relative excessive risk due to interaction, RERI) and multiplicative scale (i.e., ratio of odds ratios (ORs)).

RESULTS

In total, 71,566 cases met the inclusion criteria. For the measure of interaction between the defibrillation waveform and the time to defibrillation, ratio of ORs for ROSC was 0.84 (0.75-0.94), implying that the effect of time to first defibrillation on ROSC was negatively modified by defibrillation waveform. For the interaction between the defibrillation waveform and the number of defibrillations, RERI and ratio of ORs for CPC (1, 2) was -0.25 (-0.47 to -0.06) and 0.79 (0.67-0.93), respectively. It is implied that the effect of number of defibrillation on CPC (1, 2) was negatively modified by defibrillation waveform.

CONCLUSIONS

An increased number of defibrillations was associated with a decreased ROSC in the case of biphasic and monophasic defibrillation, while an increased number of defibrillations was related to an increased 1-month survival rate and CPC (1, 2) only in the case of biphasic defibrillation. When two or more defibrillations were performed, a biphasic waveform was more effective in terms of long-term survival than a monophasic waveform.

Basic cardiopulmonary life support (BCLS) for cardiopulmonary resuscitation by trained paramedics and medics outside the hospital

The cardiopulmonary resuscitation guideline of Basic Cardiopulmonary Life Support (BCLS) for management of adult victims with cardiopulmonary arrest outside the hospital provides an algorithmic stepwise approach for optimal outcome of the victims by trained medics and paramedics. This guideline has been developed considering the need to have a universally acceptable practice guideline for India and keeping in mind the infrastructural limitations of some areas of the country. This guideline is based on evidence elicited in the international and national literature. In the absence of data from Indian population, the excerpts have been taken from international data, discussed with Indian experts and thereafter modified to make them practically applicable across India. The optimal outcome for a victim with cardiopulmonary arrest would depend on core links of early recognition and activation; early high-quality cardiopulmonary resuscitation, early defibrillation and early transfer to medical facility. These links are elaborated in a stepwise manner in the BCLS algorithm. The BCLS also emphasise on quality check for various steps of resuscitation.

Defibrillation for Ventricular Fibrillation: A Shocking Update

Cardiac arrest is defined as the termination of cardiac activity associated with loss of consciousness, of spontaneous breathing, and of circulation. Sudden cardiac arrest and sudden cardiac death (SCD) are terms often used interchangeably. Most patients with out-of-hospital cardiac arrest have shown coronary artery disease or symptoms during the hour before the event. Cardiac arrest is potentially reversible by cardiopulmonary resuscitation, defibrillation, cardioversion, cardiac pacing, or treatments targeted at the underlying disease (e.g., acute coronary occlusion). We restrict SCD hereafter to cardiac arrest due to ventricular fibrillation, including rhythms shockable by an automatic external defibrillator (AED), implantable cardioverter-defibrillator (ICD), or wearable cardioverter-defibrillator (WCD). We summarize the state of the art related to defibrillation in treating SCD, including a brief history of the evolution of defibrillation, technical characteristics of modern AEDs, strategies to improve AED access and increase survival, ancillary treatments, and use of ICDs or WCDs.

A multicenter prospective randomized study comparing the efficacy of escalating higher biphasic versus low biphasic energy defibrillations in patients presenting with cardiac arrest in the in-hospital environment

Background

Biphasic defibrillation has been practiced worldwide for >15 years. Yet, consensus does not exist on the best energy levels for optimal outcomes when used in patients with ventricular fibrillation (VF)/pulseless ventricular tachycardia (VT).

Methods

This prospective, randomized, controlled trial of 235 adult cardiac arrest patients with VF/VT was conducted in the emergency and cardiology departments. One group received low-energy (LE) shocks at 150–150–150 J and the other escalating higher-energy (HE) shocks at 200–300–360 J. If return of spontaneous circulation (ROSC) was not achieved by the third shock, LE patients crossed over to the HE arm and HE patients continued at 360 J. Primary end point was ROSC. Secondary end points were 24-hour, 7-day, and 30-day survival.

Results

Both groups were comparable for age, sex, cardiac risk factors, and duration of collapse and VF/VT. Of the 118 patients randomized to the LE group, 48 crossed over to the HE protocol, 24 for persistent VF, and 24 for recurrent VF. First-shock termination rates for HE and LE patients were 66.67% and 64.41%, respectively (P=0.78, confidence interval: 0.65–1.89). First-shock ROSC rates were 25.64% and 29.66%, respectively (P=0.56, confidence interval: 0.46–1.45). The 24-hour, 7-day, and 30-day survival rates were 85.71%, 74.29%, and 62.86% for first-shock ROSC LE patients and 70.00%, 50.00%, and 46.67% for first-shock ROSC HE patients, respectively. Conversion rates for further shocks at 200 J and 300 J were low, but increased to 38.95% at 360 J.

Conclusion

First-shock termination and ROSC rates were not significantly different between LE and HE biphasic defibrillation for cardiac arrest patients. Patients responded best at 150/200 J and at 360 J energy levels. For patients with VF/pulseless VT, consideration is needed to escalate quickly to HE shocks at 360 J if not successfully defibrillated with 150 or 200 J initially.

Minor Variations in Electrode Pad Placement Impact Defibrillation Success

Defibrillation is essential for resuscitating patients with ventricular fibrillation (VF), but shocks often fail to defibrillate. We hypothesized that small variations in pad placement affect shock success, and that defibrillation waveform and shock dose could compensate for suboptimal pad placement. In 10 swine experiments, electrode pads were attached at 3 adjacent anterolateral positions, less than 3 centimeters apart. At each position, 24 episodes of VF were induced and shocked, 8 episodes for each of 3 defibrillation therapies. This resulted in 9 tested combinations of pad position and defibrillation therapy, with 80 episodes of VF for each combination. An episode consisted of 15 seconds of untreated VF, followed by a first shock and, if necessary, a repeat shock. Episodes were separated by four minutes of recovery. Both electrode pad position and therapy order were randomized by experiment. Primary outcome was defined as successful VF termination after the first shock; secondary outcome was the cumulative success of the first and second shocks. First shock efficacy varied widely across the 9 tested combinations of pad position and defibrillation therapy, ranging from 11.3% to 86.3%. When grouped by therapy, first shock efficacy varied significantly between the 3 pad positions: 38.3%, 48.3%, 36.7% (p = 0.02, ANOVA), and, when grouped by pad position, it varied significantly between therapies: 15.0%, 32.5%, 75.8% (p < 0.001, ANOVA). Cumulative 2-shock success varied significantly with therapy (p < 0.001, ANOVA) but not with pad position (p = 0.30, ANOVA). The lowest first shock success was at one position in 6 of 10 animals, at another position in 4 of 10 animals, and never at the third position. Small variations in pad placement can significantly affect defibrillation shock efficacy. However, anatomical variation between individuals and the challenging conditions of real-world resuscitations make optimal pad placement impractical. Suboptimal pad placement can be overcome with defibrillation waveform and shock dose.

Cardiac Arrest Resuscitation

Cardiac arrest is a dynamic disease that tests the multitasking and leadership abilities of emergency physicians. Providers must simultaneously manage the logistics of resuscitation while searching for the cause of cardiac arrest. The astute clinician will also realize that he or she is orchestrating only one portion of a larger series of events, each of which directly affects patient outcomes. Resuscitation science is rapidly evolving, and emergency providers must be familiar with the latest evidence and controversies surrounding resuscitative techniques. This article reviews evidence, discusses controversies, and offers strategies to provide quality cardiac arrest resuscitation.

Cardiopulmonary resuscitation (CPR) plus delayed defibrillation versus immediate defibrillation for out-of-hospital cardiac arrest

BACKGROUND

Sudden cardiac arrest (SCA) is a common health problem associated with high levels of mortality. Cardiac arrest is caused by three groups of dysrhythmias: ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT), pulseless electric activity (PEA) and asystole. The most common dysrhythmia found in out-of-hospital cardiac arrest (OHCA) is VF. During VF or VT, cardiopulmonary resuscitation (CPR) provides perfusion and oxygenation to the tissues, whilst defibrillation restores a viable cardiac rhythm. Early successful defibrillation is known to improve outcomes in VF/VT. However, it has been hypothesized that a period of CPR before defibrillation creates a more conducive physiological environment, increasing the likelihood of successful defibrillation. The order of priority of CPR versus defibrillation therefore remains in contention. As previous studies have remained inconclusive, we conducted a systematic review of available evidence in an attempt to draw conclusions on whether CPR plus delayed defibrillation or immediate defibrillation resulted in better outcomes in OHCA.

OBJECTIVES

To examine whether an initial one and one-half to three minutes of CPR administered by paramedics before defibrillation versus immediate defibrillation on arrival influenced survival rates, neurological outcomes or rates of return of spontaneous circulation (ROSC) in OHCA.

SEARCH METHODS

We searched the following databases: the Cochrane Central Register of Controlled trials (CENTRAL) (2013, Issue 6); MEDLINE (Ovid) (1948 to May 2013); EMBASE (1980 to May 2013); the Institute for Scientific Information (ISI) Web of Science (1980 to May 2013) and the China Academic Journal Network Publishing Database (China National Knowledge Infrastructure (CNKI), 1980 to May 2013). We included studies published in all languages. We also searched the Current Controlled Trials and Clinical Trials databases for ongoing trials. We screened the references lists of studies included in our review against the reference lists of relevant International Liaison Committee on Resuscitation (ILCOR) evidence worksheets.

SELECTION CRITERIA

Our participant group consisted of adults over 18 years of age presenting with OHCA who were in VF or pulseless VT at the time of emergency medical service (EMS) paramedic arrival. We included randomized controlled trials (RCTs) and quasi-randomized controlled trials that evaluated the effects of one and one-half to three minutes of CPR versus defibrillation as initial therapy on survival and neurological outcomes of these participants. We excluded observational and cross-over design studies.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted the data. We contacted study authors to ask for additional data when required. The risk ratio (RR) for each outcome was calculated and summarized in the meta-analysis after heterogeneity was considered. We used Review Manager software for all analyses.

MAIN RESULTS

We included four RCTs with a total of 3090 enrolled participants (one study used a cluster-randomized design). Three trials were considered to have a relatively low risk of bias, and one trial was considered to have a relatively high risk. When survival to hospital discharge was compared, 38 of 320 (11.88%) participants survived to discharge in the initial CPR plus delayed defibrillation group compared with 39 of 338 participants (11.54%) in the immediate defibrillation group (RR 1.09, 95% CI 0.54 to 2.20, Chi(2) = 10.78, degrees of freedom (df) = 5, P value 0.06, I(2) = 54%, low-quality evidence).When we compared the neurological outcome at hospital discharge (RR 1.12, 95% CI 0.65 to 1.93, low-quality evidence), the rate of return of spontaneous circulation (ROSC) (RR 0.94, 95% CI 0.77 to 1.15,low-quality evidence) and survival at one year (RR 0.77, 95% CI 0.24 to 2.49, low-quality evidence), we could not rule out the superiority of either treatment.Adverse effects were not associated with either treatment.

AUTHORS' CONCLUSIONS

Owing to the low quality of available evidence, we have been unable to determine conclusively whether immediate defibrillation and one and one-half to three minutes of CPR as initial therapy before defibrillation have similar effects on rates of return of spontaneous circulation, survival to discharge or neurological insult.We have also been unable to conclude whether either treatment approach provides a degree of superiority in OHCA.We propose that this is an area that needs further rigorous research through additional high-quality RCTs, including larger sample sizes and proper subgroup analysis.

RECOVER evidence and knowledge gap analysis on veterinary CPR. Part 7: Clinical guidelines

OBJECTIVE

To present a series of evidence-based, consensus guidelines for veterinary CPR in dogs and cats.

DESIGN

Standardized, systematic evaluation of the literature, categorization of relevant articles according to level of evidence and quality, and development of consensus on conclusions for application of the concepts to clinical practice. Questions in five domains were examined: Preparedness and Prevention, Basic Life Support, Advanced Life Support, Monitoring, and Post-Cardiac Arrest Care. Standardized worksheet templates were used for each question, and the results reviewed by the domain members, by the RECOVER committee, and opened for comments by veterinary professionals for 4 weeks. Clinical guidelines were devised from these findings and again reviewed and commented on by the different entities within RECOVER as well as by veterinary professionals.

SETTING

Academia, referral practice and general practice.

RESULTS

A total of 74 worksheets were prepared to evaluate questions across the five domains. A series of 101 individual clinical guidelines were generated. In addition, a CPR algorithm, resuscitation drug-dosing scheme, and postcardiac arrest care algorithm were developed.

CONCLUSIONS

Although many knowledge gaps were identified, specific clinical guidelines for small animal veterinary CPR were generated from this evidence-based process. Future work is needed to objectively evaluate the effects of these new clinical guidelines on CPR outcome, and to address the knowledge gaps identified through this process.

Defibrillation in children

Defibrillation is the only effective treatment for ventricular fibrillation (VF). Optimal methods for defibrillation in children are derived and extrapolated from adult data. VF occurs as the initial rhythm in 8-20% of pediatric cardiac arrests. This has fostered a new interest in determining the optimal technique for pediatric defibrillation. This review will provide a brief background of the history of defibrillation and a review of the current literature on pediatric defibrillation. The literature search was performed through PubMed, using the MeSH headings of cardiopulmonary resuscitation, defibrillation and electric countershock. The authors’ personal bibliographic files were also searched. Only published articles were chosen. The recommended energy dose has been 2 J/kg for 30 years, but recent reports may indicate that higher dosages may be more effective and safe. In 2005, the European Resuscitation Council recommended 4 J/kg as the initial dose, without escalation for subsequent shocks. Automated external defibrillators are increasingly used for pediatric cardiac arrest, and available reports indicate high success rates. Additional research on pediatric defibrillation is critical in order to be able to provide an equivalent standard of care for children in cardiac arrest and improve outcomes.

[Comments on the 2010 guidelines on cardiopulmonary resuscitation of the European Resuscitation Council]

ADULTS

Administer chest compressions (minimum 100/min, minimum 5 cm depth) at a ratio of 30:2 with ventilation (tidal volume 500-600 ml, inspiration time 1 s, F(I)O₂ if possible 1.0). Avoid any interruptions in chest compressions. After every single defibrillation attempt (initially biphasic 120-200 J, monophasic 360 J, subsequently with the respective highest energy), chest compressions are initiated again immediately for 2 min independent of the ECG rhythm. Tracheal intubation is the optimal method for securing the airway during resuscitation but should be performed only by experienced airway management providers. Laryngoscopy is performed during ongoing chest compressions; interruption of chest compressions for a maximum of 10 s to pass the tube through the vocal cords. Supraglottic airway devices are alternatives to tracheal intubation. Drug administration routes for adults and children: first choice i.v., second choice intraosseous (i.o.). Vasopressors: 1 mg epinephrine every 3-5 min i.v. After the third unsuccessful defibrillation amiodarone (300 mg i.v.), repetition (150 mg) possible. Sodium bicarbonate (50 ml 8.4%) only for excessive hyperkaliemia, metabolic acidosis, or intoxication with tricyclic antidepressants. Consider aminophylline (5 mg/kgBW). Thrombolysis during spontaneous circulation only for myocardial infarction or massive pulmonary embolism; during on-going cardiopulmonary resuscitation (CPR) only when indications of massive pulmonary embolism. Active compression-decompression (ACD-CPR) and inspiratory threshold valve (ITV-CPR) are not superior to good standard CPR.

CHILDREN

Most effective improvement of outcome by prevention of full cardiorespiratory arrest. Basic life support: initially five rescue breaths, followed by chest compressions (100-120/min depth about one third of chest diameter), compression-ventilation ratio 15:2. Foreign body airway obstruction with insufficient cough: alternate back blows and chest compressions (infants), or abdominal compressions (children >1 year). Treatment of potentially reversible causes: ("4 Hs and 4 Ts") hypoxia and hypovolaemia, hypokalaemia and hyperkalaemia, hypothermia, and tension pneumothorax, tamponade, toxic/therapeutic disturbances, thrombosis (coronary/pulmonary). Advanced life support: adrenaline (epinephrine) 10 µg/kgBW i.v. or i.o. every 3-5 min. Defibrillation (4 J/kgBW; monophasic or biphasic) followed by 2 min CPR, then ECG and pulse check. NEWBORNS: Initially inflate the lungs with bag-valve mask ventilation (p(AW) 20-40 cmH₂O). If heart rate remains <60/min, start chest compressions (120 chest compressions/min) and ventilation with a ratio 3:1. Maintain normothermia in preterm babies by covering them with foodgrade plastic wrap or similar. POSTRESUSCITATION PHASE: Early protocol-based intensive care stabilization; initiate mild hypothermia early regardless of initial cardiac rhythm [32-34°C for 12-24 h (adults) or 24 h (children); slow rewarming (<0.5°C/h)]. Consider percutaneous coronary intervention (PCI) in patients with presumed cardiac ischemia. Prediction of CPR outcome is not possible at the scene, determine neurological outcome <72 h after cardiac arrest with somatosensory evoked potentials, biochemical tests and neurological examination. ACUTE CORONARY SYNDROME: Even if only a weak suspicion of an acute coronary syndrome is present, record a prehospital 12-lead ECG. In parallel to pain therapy, administer aspirin (160-325 mg p.o. or i.v.) and clopidogrel (75-600 mg depending on strategy); in ST-elevation myocardial infarction (STEMI) and planned PCI also prasugrel (60 mg p.o.). Antithrombins, such as heparin (60 IU/kgBW, max. 4000 IU), enoxaparin, bivalirudin or fondaparinux depending on the diagnosis (STEMI or non-STEMI-ACS) and the planned therapeutic strategy. In STEMI define reperfusion strategy depending on duration of symptoms until PCI, age and location of infarction. TRAUMA: In severe hemorrhagic shock, definitive control of bleeding is the most important goal. For successful CPR of trauma patients a minimal intravascular volume status and management of hypoxia are essential. Aggressive fluid resuscitation, hyperventilation and excessive ventilation pressure may impair outcome in patients with severe hemorrhagic shock.

TRAINING

Any CPR training is better than nothing; simplification of contents and processes is the main aim.