Defibrillation threshold and cardiac responses using an external biphasic defibrillator with pediatric and adult adhesive patches in pediatric-sized piglets

Absence of Significant Myocardial Injury following Elective Direct Current Cardioversion for Atrial Fibrillation

Background

Direct current (DC) cardioversion is used to terminate cardiac arrhythmias. Current guidelines list cardioversion as a cause of myocardial injury.

Objective

This study determined whether external DC cardioversion results in myocardial injury measured by serial changes in high-sensitivity cardiac troponin T (hs-cTnT) and high-sensitivity cardiac troponin I (hs-cTnI).

Methods

This was a prospective study of patients undergoing elective external DC cardioversion for atrial fibrillation. hs-cTnT and hs-cTnI were measured precardioversion and at least 6 hours postcardioversion. Myocardial injury was present when there were significant changes in both hs-cTnT and hs-cTnI.

Results

Ninety-eight subjects were analyzed. Median cumulative energy delivered was 121.9 (interquartile range [IQR] 102.2-302.7) J. Multiple cases 23 (23.5%) required 300 J or more. Maximum cumulative energy delivered was 2455.1 J. There were small significant changes in both hs-cTnT (median precardioversion 12 [IQR 7-19) ng/L], median postcardioversion 13 [IQR 8-21] ng/L; P < .001) and hs-cTnI (median precardioversion 5 [IQR 3-10) ng/L], median postcardioversion 7 [IQR 3.6-11) ng/L; P < .001). Results were similar in patients with high-energy shocks and did not vary based on precardioversion values. Only 2 (2%) cases met criteria for myocardial injury.

Conclusion

DC cardioversion resulted in a small but statistically significant changes in hs-cTnT and hs-cTnI in 2% of patients studied irrespective of shock energy. Patients with marked troponin elevations after elective cardioversion should be assessed for other causes of myocardial injury. It should not be assumed the myocardial injury was from the cardioversion.

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.

Pediatric defibrillation shocks alone do not cause heart damage in a porcine model

•

AEDs utilize specific low energy pediatric modes to reduce myocardial damage.

•

This study applied various shocks in sinus rhythm without cardiac instrumentation.

•

Isolated clinically relevant shock sequences do not result in myocardial damage.

•

Typical variations in pediatric shocks did not affect safety and efficacy.

•

These results may inform future pediatric resuscitation guidelines.

Aim

Automated external defibrillators (AEDs) use various shock protocols with different characteristics when deployed in pediatric mode. The aim of this study is to assess and compare the safety and efficacy of different AED pediatric protocols using novel experimental approaches.

Methods

Two defibrillation protocols (A and B) were assessed across two studies: Protocol A: escalating (50–75–90 J) defibrillation waveform with higher voltage, shorter duration and equal phase durations. Protocol B; non-escalating (50–50–50 J) defibrillation waveform with lower voltage, longer duration and unequal phase durations.

Experiment 1: Isolated shock damage was assessed following shocks to 12 anesthetized pigs. Animals were randomized into two groups, receiving three shocks from Protocol A (50–75–90 J) or B (50–50–50 J). Cardiac function, cardiac troponin I (cTnI), creatine phosphokinase (CPK) and histopathology were analyzed. Experiment 2: Defibrillation safety and efficacy were assessed through shock success, ROSC, ST-segment deviation and contractility following 16 randomized shocks from protocol A or B delivered to 10 anesthetized pigs in VF.

Results

Experiment 1: No clinically meaningful difference in cTnI, CPK, ST-segment deviation, ejection fraction or histopathological damage was observed following defibrillation with either protocol. No difference was observed between protocols at any timepoint. Experiment 2: all defibrillation types demonstrated shock success and ROSC ≥ 97.5%. Post-ROSC contractility was similar between protocols.

Conclusions

There is no evidence that administration of clinically relevant shock sequences, without experimental confounders, result in significant myocardial damage in this model of pediatric resuscitation. Typical variations in AED pediatric mode settings do not affect defibrillation safety and efficacy.

[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.

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.

High-energy external defibrillation and transcutaneous pacing during MRI: feasibility and safety

BACKGROUND

Rapid application of external defibrillation, a crucial first-line therapy for ventricular fibrillation and cardiac arrest, is currently unavailable in the setting of magnetic resonance imaging (MRI), raising concerns about patient safety during MRI tests and MRI-guided procedures, particularly in patients with cardiovascular diseases. The objective of this study was to examine the feasibility and safety of defibrillation/pacing for the entire range of clinically useful shock energies inside the MRI bore and during scans, using defibrillation/pacing outside the magnet as a control.

METHODS

Experiments were conducted using a commercial defibrillator (LIFEPAK 20, Physio-Control, Redmond, Washington, USA) with a custom high-voltage, twisted-pair cable with two mounted resonant floating radiofrequency traps to reduce emission from the defibrillator and the MRI scanner. A total of 18 high-energy (200-360 J) defibrillation experiments were conducted in six swine on a 1.5 T MRI scanner outside the magnet bore, inside the bore, and during scanning, using adult and pediatric defibrillation pads. Defibrillation was followed by cardiac pacing (with capture) in a subset of two animals. Monitored signals included: high-fidelity temperature (0.01 °C, 10 samples/sec) under the pads and 12-lead electrocardiogram (ECG) using an MRI-compatible ECG system.

RESULTS

Defibrillation/pacing was successful in all experiments. Temperature was higher during defibrillation inside the bore and during scanning compared with outside the bore, but the differences were small (ΔT: 0.5 and 0.7 °C, p = 0.01 and 0.04, respectively). During scans, temperature after defibrillation tended to be higher for pediatric vs. adult pads (p = 0.08). MR-image quality (signal-to-noise ratio) decreased by ~ 10% when the defibrillator was turned on.

CONCLUSIONS

Our study demonstrates the feasibility and safety of in-bore defibrillation for the full range of defibrillation energies used in clinical practice, as well as of transcutaneous cardiac pacing inside the MRI bore. Methods for Improving MR-image quality in the presence of a working defibrillator require further study.

Prescribing an automated external defibrillator for children at increased risk of sudden arrhythmic death

BACKGROUND

Automated external defibrillators can be life-saving in out-of-hospital cardiac arrest.

OBJECTIVE

Our aim was to review our experience of prescribing automated external defibrillators for children at increased risk of sudden arrhythmic death.

METHODS

We reviewed all automated external defibrillators issued by the Scottish Paediatric Cardiac Electrophysiology Service from 2005 to 2015. All parents were given resuscitation training according to the Paediatric Resuscitation Guidelines, including the use of the automated external defibrillator.

RESULTS

A total of 36 automated external defibrillators were issued to 36 families for 44 children (27 male). The mean age at issue was 8.8 years. Diagnoses at issue included long QT syndrome (50%), broad complex tachycardia (14%), hypertrophic cardiomyopathy (11%), and catecholaminergic polymorphic ventricular tachycardia (9%). During the study period, the automated external defibrillator was used in four (9%) children, and in all four the automated external defibrillator correctly discriminated between a shockable rhythm - polymorphic ventricular tachycardia/ventricular fibrillation in three patients with one or more shocks delivered - and non-shockable rhythm - sinus rhythm in one patient. Of the three children, two of them who received one or more shocks for ventricular fibrillation/polymorphic ventricular tachycardia survived, but one died as a result of recurrent torsades de pointes. There were no other deaths.

CONCLUSION

Parents can be taught to recognise cardiac arrest, apply resuscitation skills, and use an automated external defibrillator. Prescribing an automated external defibrillator should be considered for children at increased risk of sudden arrhythmic death, especially where the risk/benefit ratio of an implantable defibrillator is unclear or delay to defibrillator implantation is deemed necessary.

External and internal biphasic direct current shock doses for pediatric ventricular fibrillation and pulseless ventricular tachycardia

OBJECTIVE

To determine energy dose and number of biphasic direct current shocks for pediatric ventricular fibrillation (VF) and pulseless ventricular tachycardia (VT).

DESIGN

Observation of preshock and postshock rhythms, energy doses, and number of shocks.

SETTING

Pediatric hospital.

PATIENTS

Shockable ventricular dysrhythmias.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Forty-eight patients with VF or pulseless VT received external shock at 1.7 ± 0.8 (mean ± SD) J/kg. Return of spontaneous circulation (ROSC) occurred in 23 (48%) patients with 2.0 ± 1.0 J/kg, but 25 (52%) patients remained in VF after 1.5 ± 0.7 J/kg (p = .05). In 24 non-responding patients, additional 1-8 shocks (final dose, 2.8 ± 1.2 J/kg) achieved ROSC in 14 (58%) with 2.6 ± 1.1 J/kg but not in 10 (42%) with 3.2 ± 1.2 J/kg (not significant). Overall, 37 (77%) patients achieved ROSC with 2.2 ± 1.1 J/kg (range, 0.5-5.0 J/kg). Eight patients without ROSC recovered with cardiopulmonary bypass and internal direct current shock. At 13 subsequent episodes of VF or VT among eight patients, five achieved ROSC and survived. In combined first and subsequent resuscitative episodes, doses in the range of 2.5 to < 3 J/kg achieved most cases of ROSC. Survival for > 1 yr was seen in 28 (78%) of 36 patients with VF and seven (58%) of 11 patients with VT, with 35 (73%) overall. Lack of ROSC was associated with multiple shocks (p = .003). Repeated shocks with adhesive pads had significantly less impedance (p < .001). Pads in an anteroposterior position achieved highest ROSC rate. Internal shock for another 48 patients with VF or VT achieved ROSC in 28 (58%) patients with 0.7 ± 0.4 J/kg but not in 20 patients with 0.4 ± 0.3 J/kg (p = .01). Nineteen of the nonresponders who received additional internal 1-9 shocks at 0.6 ± 0.5 J/kg and one patient given extracorporeal membrane oxygenation all recovered, yielding 100% ROSC, but 1-yr survival tallied 43 (90%) patients.

CONCLUSIONS

The initial biphasic direct current external shock dose of 2 J/kg for VF or pulseless VT is inadequate. Appropriate doses for initial and subsequent shocks seem to be in the range of 3-5 J/kg. Multiple shocks do not favor ROSC. The dose for internal shock is 0.6-0.7 J/kg.

Effect of defibrillation energy dose during in-hospital pediatric cardiac arrest

OBJECTIVE

To examine the effectiveness of initial defibrillation attempts. We hypothesized that (1) an initial shock dose of 2 ± 10 J/kg would be less effective for terminating fibrillation than suggested in published historical data and (2) a 4 J/kg shock dose would be more effective.

PATIENTS AND METHODS

This was a National Registry of Cardiopulmonary Resuscitation prospective, multisite, observational study of in-hospital pediatric (aged ≤18 years) ventricular fibrillation or pulseless ventricular tachycardia cardiac arrests from 2000-2008. Termination of ventricular fibrillation or pulseless ventricular tachycardia and event survival after initial shocks of 2 J/kg were compared with historic controls and a 4 J/kg shock dose.

RESULTS

Of 266 children with 285 events, 173 of 285 (61%) survived the event and 61 of 266 (23%) survived to discharge. Termination of fibrillation after initial shock was achieved for 152 of 285 (53%) events. Termination of fibrillation with 2 ± 10 J/kg was much less frequent than that seen among historic control subjects (56% vs 91%; P < .001), but not different than 4 J/kg. Compared with 2 J/kg, an initial shock dose of 4 J/kg was associated with lower rates of return of spontaneous circulation (odds ratio: 0.41 [95% confidence interval: 0.21-0.81]) and event survival (odds ratio: 0.42 [95% confidence interval: 0.18-0.98]).

CONCLUSIONS

The currently recommended 2 J/kg initial shock dose for in-hospital cardiac arrest was substantially less effective than previously published. A higher initial shock dose (4 J/kg) was not associated with superior termination of ventricular fibrillation or pulseless ventricular tachycardia or improved survival rates. The optimal pediatric defibrillation dose remains unknown.

Part 10: Pediatric basic and advanced life support: 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations

Note From the Writing Group: Throughout this article, the reader will notice combinations of superscripted letters and numbers (eg, “Family Presence During ResuscitationPeds-003”). These callouts are hyperlinked to evidence-based worksheets, which were used in the development of this article. An appendix of worksheets, applicable to this article, is located at the end of the text. The worksheets are available in PDF format and are open access.

Comparison of low-energy versus high-energy biphasic defibrillation shocks following prolonged ventricular fibrillation

INTRODUCTION

Since the initial development of the defibrillator, there has been concern that, while delivery of a large electric shock would stop fibrillation, it would also cause damage to the heart. This concern has been raised again with the development of the biphasic defibrillator.

OBJECTIVE

To compare defibrillation efficacy, postshock cardiac function, and troponin I levels following 150-J and 360-J shocks.

METHODS

Nineteen swine were anesthetized with isoflurane and instrumented with pressure catheters in the left ventricle, aorta, and right atrium. The animals were fibrillated for 6 minutes, followed by defibrillation with either low-energy (n = 8) or high-energy (n = 11) shocks. After defibrillation, chest compressions were initiated and continued until return of spontaneous circulation (ROSC). Epinephrine, 0.01 mg/kg every 3 minutes, was given for arterial blood pressure < 50 mmHg. Hemodynamic parameters were recorded for four hours. Transthoracic echocardiography was performed and troponin I levels were measured at baseline and four hours following ventricular fibrillation (VF).

RESULTS

Survival rates at four hours were not different between the two groups (low-energy, 5 of 8; high-energy, 7 of 11). Results for arterial blood pressure, positive dP/dt (first derivative of pressure measured over time, a measure of left ventricular contractility), and negative dP/dt at the time of lowest arterial blood pressure (ABP) following ROSC were not different between the two groups (p = not significant [NS]), but were lower than at baseline. All hemodynamic measures returned to baseline by four hours. Ejection fractions, stroke volumes, and cardiac outputs were not different between the two groups at four hours. Troponin I levels at four hours were not different between the two groups (12 +/- 11 ng/mL versus 21 +/- 26 ng/mL, p = NS) but were higher at four hours than at baseline (19 +/- 19 ng/mL versus 0.8 +/- 0.5 ng/mL, p < 0.05, groups combined).

CONCLUSION

Biphasic 360-J shocks do not cause more cardiac damage than biphasic 150-J shocks in this animal model of prolonged VF and resuscitation.

Post-cardiac arrest syndrome: Epidemiology, pathophysiology, treatment, and prognostication: A scientific statement from the International Liaison Committee on Resuscitation; the American Heart Association Emergency Cardiovascular Care Committee; the Council on Cardiovascular Surgery and Anesthesia; the Council on Cardiopulmonary, Perioperative, and Critical Care; the Council on Clinical Cardiology; the Council on Stroke (Part 1)

AIM OF THE REVIEW

To review the epidemiology, pathophysiology, treatment and prognostication in relation to the post-cardiac arrest syndrome.

METHODS

Relevant articles were identified using PubMed, EMBASE and an American Heart Association EndNote master resuscitation reference library, supplemented by hand searches of key papers. Writing groups comprising international experts were assigned to each section. Drafts of the document were circulated to all authors for comment and amendment.

RESULTS

The 4 key components of post-cardiac arrest syndrome were identified as (1) post-cardiac arrest brain injury, (2) post-cardiac arrest myocardial dysfunction, (3) systemic ischaemia/reperfusion response, and (4) persistent precipitating pathology.

CONCLUSIONS

A growing body of knowledge suggests that the individual components of the postcardiac arrest syndrome are potentially treatable.

Post-cardiac arrest syndrome: epidemiology, pathophysiology, treatment, and prognostication. A Scientific Statement from the International Liaison Committee on Resuscitation; the American Heart Association Emergency Cardiovascular Care Committee; the Council on Cardiovascular Surgery and Anesthesia; the Council on Cardiopulmonary, Perioperative, and Critical Care; the Council on Clinical Cardiology; the Council on Stroke

AIM OF THE REVIEW

To review the epidemiology, pathophysiology, treatment and prognostication in relation to the post-cardiac arrest syndrome.

METHODS

Relevant articles were identified using PubMed, EMBASE and an American Heart Association EndNote master resuscitation reference library, supplemented by hand searches of key papers. Writing groups comprising international experts were assigned to each section. Drafts of the document were circulated to all authors for comment and amendment.

RESULTS

The 4 key components of post-cardiac arrest syndrome were identified as (1) post-cardiac arrest brain injury, (2) post-cardiac arrest myocardial dysfunction, (3) systemic ischaemia/reperfusion response, and (4) persistent precipitating pathology.

CONCLUSIONS

A growing body of knowledge suggests that the individual components of the post-cardiac arrest syndrome are potentially treatable.

Attenuating the defibrillation dosage decreases postresuscitation myocardial dysfunction in a swine model of pediatric ventricular fibrillation

OBJECTIVE

The optimal biphasic defibrillation dose for children is unknown. Postresuscitation myocardial dysfunction is common and may be worsened by higher defibrillation doses. Adult-dose automated external defibrillators are commonly available; pediatric doses can be delivered by attenuating the adult defibrillation dose through a pediatric pads/cable system. The objective was to investigate whether unattenuated (adult) dose biphasic defibrillation results in greater postresuscitation myocardial dysfunction and damage than attenuated (pediatric) defibrillation.

DESIGN

Laboratory animal experiment.

SETTING

University animal laboratory.

SUBJECTS

Domestic swine weighing 19 +/- 3.6 kg.

INTERVENTIONS

Fifty-two piglets were randomized to receive biphasic defibrillation using either adult-dose shocks of 200, 300, and 360 J or pediatric-dose shocks of approximately 50, 75, and 85 J after 7 mins of untreated ventricular fibrillation. Contrast left ventriculograms were obtained at baseline and then at 1, 2, 3, and 4 hrs postresuscitation. Postresuscitation left ventricular ejection fraction and cardiac troponins were evaluated.

MEASUREMENTS AND MAIN RESULTS

By design, piglets in the adult-dose group received shocks with more energy (261 +/- 65 J vs. 72 +/- 12 J, p < .001) and higher peak current (37 +/- 8 A vs. 13 +/- 2 A, p < .001) at the largest defibrillation dose needed. In both groups, left ventricular ejection fraction was reduced significantly at 1, 2, and 4 hrs from baseline and improved during the 4 hrs postresuscitation. The decrease in left ventricular ejection fraction from baseline was greater after adult-dose defibrillation. Plasma cardiac troponin levels were elevated 4 hrs postresuscitation in 11 of 19 adult-dose piglets vs. four of 20 pediatric-dose piglets (p = .02).

CONCLUSIONS

Unattenuated adult-dose defibrillation results in a greater frequency of myocardial damage and worse postresuscitation myocardial function than pediatric doses in a swine model of prolonged out-of-hospital pediatric ventricular fibrillation cardiac arrest. These data support the use of pediatric attenuating electrodes with adult biphasic automated external defibrillators to defibrillate children.

Comparison of rectilinear biphasic waveform with biphasic truncated exponential waveform in a pediatric defibrillation model

OBJECTIVE

To compare the rectilinear biphasic waveform with a biphasic truncated exponential waveform for pediatric defibrillation.

DESIGN

Prospective, randomized study.

SETTING

Experimental laboratory of a university-affiliated research institute.

SUBJECTS

Male domestic piglets (4-24 kg).

INTERVENTIONS

Eleven piglets (4-8 kg), which represented a patient <1 yr old, and ten piglets (16-24 kg), which represented a pediatric patient between the ages of 2 and 8 yrs, were anesthetized, intubated, and mechanically ventilated. Ventricular fibrillation was induced and maintained for 30 secs, and a predetermined shock was then delivered to defibrillate. Following defibrillation, the animal was permitted to stabilize hemodynamically for 4 mins. Fifty shocks were applied to each animal using a randomization schedule based on a predetermined permutation of 50. The 50 shocks were 25 shocks for each rectilinear biphasic and biphasic truncated exponential waveforms, comprising five shocks at five energy settings. Each group of five shocks was fixed at a predetermined energy value, depending on the body weight of the animal. Dose-response curves were constructed using logistic regression. Aortic pressure, electrocardiogram, left ventricular pressure, and left ventricular pressure value of 40 mm Hg were continually measured.

MEASUREMENTS AND MAIN RESULTS

Dose-response curves determined defibrillation thresholds at 50% (D50) and 90% (D90) probability of success. The rectilinear biphasic waveform defibrillated with <90% of the D50 and D90 energies required for a biphasic truncated exponential waveform. The rectilinear biphasic waveform also successfully defibrillated with significantly less energy per body weight and per heart weight compared with a biphasic truncated exponential waveform.

CONCLUSIONS

The rectilinear biphasic waveform has superior defibrillation performance compared with a biphasic truncated exponential waveform in a piglet defibrillation model for young children.

Ventricular fibrillation and the use of automated external defibrillators on children

The use of automated external defibrillators (AEDs) has been advocated in recent years as a part of the chain of survival to improve outcomes for adult cardiac arrest victims. When AEDs first entered the market, they were not tested for pediatric usage and rhythm interpretation. In addition, the presumption was that children do not experience ventricular fibrillation, so they would not benefit from use of AEDs. Recent literature has shown that children do experience ventricular fibrillation, and this rhythm has a better outcome than do other cardiac arrest rhythms. At the same time, the arrhythmia software on AEDs has become more extensive and validated for children, and attenuation devices have become available to downregulate the energy delivered by AEDs to allow their use in children. Pediatricians are now being asked whether AED programs should be implemented, and where they are being implemented, pediatricians are being asked to provide guidance on the use of AEDs in children. As AED programs expand, pediatricians must advocate on behalf of children so that their needs are accounted for in these programs. For pediatricians to be able to provide guidance and ensure that children are included in AED programs, it is important for pediatricians to know how AEDs work, be up-to-date on the literature regarding pediatric fibrillation and energy delivery, and understand the role of AEDs as life-saving interventions for children.

Pediatric defibrillation after cardiac arrest: initial response and outcome

Introduction

Shockable rhythms are rare in pediatric cardiac arrest and the results of defibrillation are uncertain. The objective of this study was to analyze the results of cardiopulmonary resuscitation that included defibrillation in children.

Methods

Forty-four out of 241 children (18.2%) who were resuscitated from inhospital or out-of-hospital cardiac arrest had been treated with manual defibrillation. Data were recorded according to the Utstein style. Outcome variables were a sustained return of spontaneous circulation (ROSC) and one-year survival. Characteristics of patients and of resuscitation were evaluated.

Results

Cardiac disease was the major cause of arrest in this group. Ventricular fibrillation (VF) or pulseless ventricular tachycardia (PVT) was the first documented electrocardiogram rhythm in 19 patients (43.2%). A shockable rhythm developed during resuscitation in 25 patients (56.8%). The first shock (dose, 2 J/kg) terminated VF or PVT in eight patients (18.1%). Seventeen children (38.6%) needed more than three shocks to solve VF or PVT. ROSC was achieved in 28 cases (63.6%) and it was sustained in 19 patients (43.2%). Only three patients (6.8%), however, survived at 1-year follow-up. Children with VF or PVT as the first documented rhythm had better ROSC, better initial survival and better final survival than children with subsequent VF or PVT. Children who survived were older than the finally dead patients. No significant differences in response rate were observed when first and second shocks were compared. The survival rate was higher in patients treated with a second shock dose of 2 J/kg than in those who received higher doses. Outcome was not related to the cause or the location of arrest. The survival rate was inversely related to the duration of cardiopulmonary resuscitation.

Conclusion

Defibrillation is necessary in 18% of children who suffer cardiac arrest. Termination of VF or PVT after the first defibrillation dose is achieved in a low percentage of cases. Despite a sustained ROSC being obtained in more than one-third of cases, the final survival remains low. The outcome is very poor when a shockable rhythm develops during resuscitation efforts. New studies are needed to ascertain whether the new international guidelines will contribute to improve the outcome of pediatric cardiac arrest.

Potential benefit of transesophageal defibrillation: an experimental evaluation

INTRODUCTION

Because of the proximity of the esophagus to the heart, transesophageal defibrillation might increase defibrillation success. We assessed the defibrillation threshold (DFT) of transesophageal defibrillation compared with standard transthoracic defibrillation.

METHODS

Defibrillation success and DFTs were determined in 22 female pigs with high (68+/-4 kg, n=12) or low body weight (39+/-1 kg, n=10). After induction of ventricular fibrillation, biphasic shocks were delivered between two cutaneous patch electrodes (sternal and apical position) or between an esophageal and two cutaneous patch electrodes in a sternal and apical position. The esophageal electrode was integrated into a latex sheath covering a standard transesophageal echocardiography probe.

RESULTS

In 5 of 12 pigs with high body weight, external defibrillation failed despite 3 consecutive 200-J shocks, whereas subsequent transesophageal defibrillation was successful with the first shock. In the remaining 7 pigs, a more than 50% reduction in DFT was obtained with transesophageal defibrillation compared with standard biphasic external defibrillation (67+/-27 vs 164+/-23 J, P<.001). Pigs with lower body weight were successfully defibrillated by both transthoracic and transesophageal shocks. The DFT in pigs with low body weight was significantly lower using transesophageal defibrillation compared with transthoracic shocks (65+/-15 vs 99+/-38 J, P<.05).

CONCLUSIONS

In this animal model, nonresponders to standard external defibrillation could successfully be defibrillated via an esophageal-cutaneous electrode configuration. Overall, an almost 50% DFT reduction was achieved by transesophageal defibrillation. Transesophageal defibrillation may provide an additional tool for terminating VF, which is refractory to external defibrillation, eg, in patients with very high body weight.

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.

The International Liaison Committee on Resuscitation (ILCOR) consensus on science with treatment recommendations for pediatric and neonatal patients: pediatric basic and advanced life support

This publication contains the pediatric and neonatal sections of the 2005 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations (COSTR). The consensus process that produced this document was sponsored by the International Liaison Committee on Resuscitation (ILCOR). ILCOR was formed in 1993 and consists of representatives of resuscitation councils from all over the world. Its mission is to identify and review international science and knowledge relevant to cardiopulmonary resuscitation (CPR) and emergency cardiovascular care (ECC) and to generate consensus on treatment recommendations. ECC includes all responses necessary to treat life-threatening cardiovascular and respiratory events. The COSTR document presents international consensus statements on the science of resuscitation. ILCOR member organizations are each publishing resuscitation guidelines that are consistent with the science in this consensus document, but they also take into consideration geographic, economic, and system differences in practice and the regional availability of medical devices and drugs. The American Heart Association (AHA) pediatric and the American Academy of Pediatrics/AHA neonatal sections of the resuscitation guidelines are reprinted in this issue of Pediatrics (see pages e978-e988). The 2005 evidence evaluation process began shortly after publication of the 2000 International Guidelines for CPR and ECC. The process included topic identification, expert topic review, discussion and debate at 6 international meetings, further review, and debate within ILCOR member organizations and ultimate approval by the member organizations, an Editorial Board, and peer reviewers. The complete COSTR document was published simultaneously in Circulation (International Liaison Committee on Resuscitation. 2005 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. Circulation. 2005;112(suppl):73-90) and Resuscitation (International Liaison Committee on Resuscitation. 2005 International Consensus Conference on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. Resuscitation. 2005;67:271-291). Readers are encouraged to review the 2005 COSTR document in its entirety. It can be accessed through the CPR and ECC link at the AHA Web site: www.americanheart.org. The complete publication represents the largest evaluation of resuscitation literature ever published and contains electronic links to more detailed information about the international collaborative process. To organize the evidence evaluation, ILCOR representatives established 6 task forces: basic life support, advanced life support, acute coronary syndromes, pediatric life support, neonatal life support, and an interdisciplinary task force to consider overlapping topics such as educational issues. The AHA established additional task forces on stroke and, in collaboration with the American Red Cross, a task force on first aid. Each task force identified topics requiring evaluation and appointed international experts to review them. A detailed worksheet template was created to help the experts document their literature review, evaluate studies, determine levels of evidence, develop treatment recommendations, and disclose conflicts of interest. Two evidence evaluation experts reviewed all worksheets and assisted the worksheet reviewers to ensure that the worksheets met a consistently high standard. A total of 281 experts completed 403 worksheets on 275 topics, reviewing more than 22000 published studies. In December 2004 the evidence review and summary portions of the evidence evaluation worksheets, with worksheet author conflict of interest statements, were posted on the Internet at www.C2005.org, where readers can continue to access them. Journal advertisements and e-mails invited public comment. Two hundred forty-nine worksheet authors (141 from the United States and 108 from 17 other countries) and additional invited experts and reviewers attended the 2005 International Consensus Conference for presentation, discussion, and debate of the evidence. All 380 participants at the conference received electronic copies of the worksheets. Internet access was available to all conference participants during the conference to facilitate real-time verification of the literature. Expert reviewers presented topics in plenary, concurrent, and poster conference sessions with strict adherence to a novel and rigorous conflict of interest process. Presenters and participants then debated the evidence, conclusions, and draft summary statements. Wording of science statements and treatment recommendations was refined after further review by ILCOR member organizations and the international editorial board. This format ensured that the final document represented a truly international consensus process. The COSTR manuscript was ultimately approved by all ILCOR member organizations and by an international editorial board. The AHA Science Advisory and Coordinating Committee and the editor of Circulation obtained peer reviews of this document before it was accepted for publication. The most important changes in recommendations for pediatric resuscitation since the last ILCOR review in 2000 include: Increased emphasis on performing high quality CPR: "Push hard, push fast, minimize interruptions of chest compression; allow full chest recoil, and don't provide excessive ventilation" Recommended chest compression-ventilation ratio: For lone rescuers with victims of all ages: 30:2 For health care providers performing 2-rescuer CPR for infants and children: 15:2 (except 3:1 for neonates) Either a 2- or 1-hand technique is acceptable for chest compressions in children Use of 1 shock followed by immediate CPR is recommended for each defibrillation attempt, instead of 3 stacked shocks Biphasic shocks with an automated external defibrillator (AED) are acceptable for children 1 year of age. Attenuated shocks using child cables or activation of a key or switch are recommended in children <8 years old. Routine use of high-dose intravenous (IV) epinephrine is no longer recommended. Intravascular (IV and intraosseous) route of drug administration is preferred to the endotracheal route. Cuffed endotracheal tubes can be used in infants and children provided correct tube size and cuff inflation pressure are used. Exhaled CO2 detection is recommended for confirmation of endotracheal tube placement. Consider induced hypothermia for 12 to 24 hours in patients who remain comatose following resuscitation. Some of the most important changes in recommendations for neonatal resuscitation since the last ILCOR review in 2000 include less emphasis on using 100% oxygen when initiating resuscitation, de-emphasis of the need for routine intrapartum oropharyngeal and nasopharyngeal suctioning for infants born to mothers with meconium staining of amniotic fluid, proven value of occlusive wrapping of very low birth weight infants <28 weeks' gestation to reduce heat loss, preference for the IV versus the endotracheal route for epinephrine, and an increased emphasis on parental autonomy at the threshold of viability. The scientific evidence supporting these recommendations is summarized in the neonatal document (see pages e978-e988).

Attenuated pediatric electrode pads for automated external defibrillator use in children

OBJECTIVE

This post-market, observational study is intended to evaluate reported uses of pediatric pads that reduce the energy delivered by some adult automated external defibrillators (AEDs) so that they may be used with pediatric patients.

METHODS

Users of the pediatric pads were asked to report any use of the pads, even if no shock was delivered and to provide detailed information about the event, caregiver and the patient.

RESULTS

Reports of the use of pediatric pads have been received and confirmed for 27 patients, age range 0 days to 23 years, median 2 years. Ventricular fibrillation (VF) was reported in eight cases, age range 4.5 months to 10 years, median 3 years. Shocks were delivered to all VF patients, the average shock number was 1.9, range 1-4. All patients had termination of VF, were admitted to the hospital and five survived to hospital discharge. Non-shockable rhythms were reported in 16 patients, and the AED appropriately did not advise a shock. Eleven of these patients had asystole or PEA as their initial rhythm and did not survive to hospital discharge. One report contained no additional information other than that the patient did not survive, and in two other reports, the pads were not applied to patients.

CONCLUSIONS

Voluntary reports of the use of attenuated pediatric defibrillation pads indicate the devices performed appropriately. All eight VF patients had termination of VF and five survived to hospital discharge. These data support the rapid deployment of AEDs for young children as well as adolescents and adults. Since the pediatric pads are available and deliver an appropriate dose for children, their use should be strongly encouraged.

Effect of transthoracic shocks on left ventricular function

Although defibrillating shocks are thought to depress ventricular function transiently, the independent effects of high strength shocks (without the metabolic sequelae of pre-shock fibrillation) have not been assessed systematically in humans. Therefore, we delivered three consecutive synchronized monophasic transthoracic shocks (200, 200 and 360 J) at 60s intervals during sinus rhythm and evaluated the effect on left ventricular chamber size and function as determined by transesophageal echocardiography in 11 patients (mean age 67+/-8 years, 9M/2F) with depressed left ventricular function (left ventricular ejection fraction: 14-37%). The shocks did not alter hemodynamics consistently. On average, the shocks did not alter stroke volume, cardiac output, left ventricular ejection fraction or regional wall thickening (all p>0.05 versus baseline). This effect was highly variable and 36% of patients experienced a >25% reduction in cardiac output by the final shock. There was a tendency for regional wall thickening to worsen in the best baseline sextant with an offsetting significant increase in thickening in the worst baseline sextant (p=0.05). Thus, repetitive defibrillation strength transthoracic shocks do not impair left ventricular function consistently in patients with cardiomyopathy. However, the effect is widely variable and potentially important depression of left ventricular function does occur in some patients.

Better outcome after pediatric defibrillation dosage than adult dosage in a swine model of pediatric ventricular fibrillation

OBJECTIVES

This study was designed to compare outcome after adult defibrillation dosing versus pediatric dosing in a piglet model of prolonged prehospital ventricular fibrillation (VF).

BACKGROUND

Weight-based 2 to 4 J/kg monophasic defibrillation dosing is recommended for children in VF, but impractical for automated external defibrillator (AED) use. Present AEDs can only provide adult shock doses or newly developed attenuated adult doses intended for children. A single escalating energy sequence (50/75/86 J) of attenuated adult-dose biphasic shocks (pediatric dosing) is at least as effective as escalating monophasic weight-based dosing for prolonged VF in piglets, but this approach has not been compared to standard adult biphasic dosing.

METHODS

Following 7 min of untreated VF, piglets weighing 13 to 26 kg (19 +/- 1 kg) received either biphasic 50/75/86 J (pediatric dose) or biphasic 200/300/360 J (adult dose) therapies during simulated prehospital life support.

RESULTS

Return of spontaneous circulation was attained in 15 of 16 pediatric-dose piglets and 14 of 16 adult-dose piglets. Four hours postresuscitation, pediatric dosing resulted in fewer elevations of cardiac troponin T (0 of 12 piglets vs. 6 of 11 piglets, p = 0.005) and less depression of left ventricular ejection fraction (p < 0.05). Most importantly, more piglets survived to 24 h with good neurologic scores after pediatric shocks than adult shocks (13 of 16 piglets vs. 4 of 16 piglets, p = 0.004).

CONCLUSIONS

In this model, pediatric shocks resulted in superior outcome compared with adult shocks. These data suggest that adult defibrillation dosing may be harmful to pediatric patients with VF and support the use of attenuating electrodes with adult biphasic AEDs to defibrillate children.

Attenuated adult biphasic shocks for prolonged pediatric ventricular fibrillation: support for pediatric automated defibrillators

OBJECTIVE

To evaluate published data regarding the treatment of prolonged pediatric defibrillation, with special emphasis on the use of attenuated adult biphasic shocks for pediatric defibrillation.

DESIGN

Review relevant human and animal literature.

RESULTS

Rhythm analysis algorithms from two manufacturers of automated external defibrillators can accurately distinguish shockable from nonshockable rhythms in children. Theoretical considerations and transthoracic impedance data from animals and children suggest that pediatric defibrillation doses should not necessarily vary in a simple weight-based manner. Two piglet studies have established that an attenuated adult biphasic dosage can be successfully used for 3.5- to 24-kg animals in ventricular fibrillation. One study established that the attenuated adult biphasic dosage was at least as safe and effective as the standard monophasic weight-based dosing.

CONCLUSION

This review supports the American Heart Association's new guidelines for pediatric automated external defibrillator usage: "Automated external defibrillators may be used for children 1 to 8 yrs of age who have no signs of circulation. Ideally the device should deliver a pediatric dose. The arrhythmia detection system used in the device should demonstrate high specificity for pediatric shockable rhythms, i.e., it will not recommend delivery of a shock for nonshockable rhythms."

Automated external defibrillators: safety and efficacy in children and adolescents

Although children do not suffer from ventricular fibrillation (VF) as frequently as adults, it does occur in 10% to 20% of pediatric cardiac arrests. The technology is available to recognize and treat ventricular fibrillation in children as quickly as we can for adults. This article discusses the evidence to support automated external defibrillator use in young children. As this technology gains increased acceptance, resuscitation rates and outcomes for VF in children should approach those that are seen in adults.

Attenuated adult biphasic shocks compared with weight-based monophasic shocks in a swine model of prolonged pediatric ventricular fibrillation

AIM

To compare the safety and efficacy of attenuated adult biphasic shocks with standard monophasic weight-based shocks in a piglet model of prolonged prehospital ventricular fibrillation (VF).

BACKGROUND

If attenuated adult shocks are safe and effective for prehospital pediatric VF, automated external defibrillators (AEDs) can be easily adapted for pediatric use.

METHODS

After 7 min of untreated VF, piglets were randomized to treatment with attenuated adult biphasic shocks or weight-based monophasic shocks. The attenuated adult biphasic group received 200/300/360 J shocks, attenuated by specialized pediatric electrodes to 51/78/81 J and the monophasic weight-based control group received 2/4/4 J/kg shocks. Forty-eight female piglets were studied, 16 in each of three weight categories: 4 kg (neonatal), 14 kg (younger child) and 24 kg (older child). The primary outcome measures of efficacy and safety were 24h survival with good neurological outcome and post-resuscitation left ventricular ejection fraction (LVEF), respectively.

RESULTS

For the 24 kg piglets, attenuated adult biphasic shocks resulted in superior 24 h survival with good neurological outcome (6/8 versus 0/8, P < 0.001) and greater LVEF 4 h post-resuscitation (34 +/- 4% versus 18 +/- 5%, P < 0.05). For the 14 and 4 kg piglets, 24 h survival with good neurological outcome occurred in 7/8 versus 5/8 and 7/8 versus 3/8, respectively, and LVEF 4 h post-resuscitation was 30 +/- 3% versus 36 +/- 6% and 30 +/- 3% versus 22 +/- 4%, respectively.

CONCLUSIONS

The escalating attenuated adult biphasic dosage strategy was at least as safe and effective as the standard weight-based monophasic dose over a wide range of weights in this piglet model of prehospital VF. This work supports the concept of using an attenuated adult biphasic dosage in children.

Do clinically relevant transthoracic defibrillation energies cause myocardial damage and dysfunction?

Sufficiently strong defibrillation shocks will cause temporary or permanent damage to the heart. Weak defibrillation shocks do not cause any damage to the heart but also do not defibrillate. A relevant and practical question is what range of shock energies is most likely to defibrillate while not causing damage to the heart. This question is most difficult to answer in the pre-hospital defibrillation setting where the patients' size and shape vary, placement of the defibrillation patches vary, and the etiology of their arrhythmia varies. Unlike internal defibrillators, which are tested at implantation, efficacy of an external defibrillator is determined only once, when it is most needed. This review discusses shock damage and dysfunction caused by monophasic waveforms as well as biphasic waveforms. Evidence is presented suggesting that for perfused hearts, the threshold for damage is well above any shock size delivered clinically. For non-perfused hearts, both in humans and animals, evidence is presented that monophasic shocks of up to 5 J/kg do not cause any more cardiac damage/dysfunction than that associated with smaller shocks and that much of this damage is caused by the ischemic period itself rather than the shock. Although many patients can be defibrillated with 150 J (2.2 J/kg) biphasic shocks, some patients may require biphasic shocks up to 360 J (5 J/kg) to be defibrillated. Studies still need to be performed comparing the efficacy and damaging effects of 360 J biphasic shocks to 150 J biphasic shocks. Until those studies are completed, it seems reasonable to use the same 360 J (5 J/kg) energy limit for biphasic shocks as for monophasic shocks.