Defibrillation Waveforms Research Articles

Amplitude of spectral area of ventricular fibrillation as a guide for low energy defibrillation level in patients with out-of-hospital cardiac arrest

Abstract Funding Acknowledgements Type of funding sources: None. Introduction The optimal energy level for shock in biphasic waveform defibrillation represents a significant knowledge gap. Different energy regimens have been trialed; however, a selection criterion which may help in adopting one approach over another has never been identified. Choosing the maximum energy may be an option but current-induced myocardial damage should not be neglected and an effort to tailor energy delivery is desirable. Purpose To assess whether amplitude spectral area (AMSA) of VF can guide the dose-regimens of defibrillation in out-of-hospital cardiac arrest (OHCA) patients. Methods This is a multicenter study based on the data from some of the largest OHCA registers in Europe, which enrolled 830 OHCA patients who received at least one shock during advanced resuscitation. AMSA values were calculated by retrospectively analyzing the data collected by the Corpuls 3 and LIFEPAK 12/15 monitors/defibrillators and by using a 2-second-pre-shock ECG interval. Results Among 830 OHCAs, 2135 shocks were delivered from a minimum energy level of 150 J to a maximum of 360 J. The AMSA values of efficacious shocks delivered at 150 J were higher compared to those of efficacious shock at 360 J [13.1 (IQR 10.2-17.1) vs 11.8 (IQR 8.3-15.2) HzxmV; p<0.01). In a multivariate analysis corrected for time to each shock, sex, age, amiodarone administration and study center, AMSA values, and not the dose of the shock energy, was significantly associated with the probability of shock success [OR 5.8, (95%CI 4.7-7.3); p< 0.01]. By dividing the total shocks into three tertiles based on AMSA values (T1: 0.8-6.9 Hz×mV; T2: 6.9-11.8 Hz×mV; T3: 11.8-63.2 Hz×mV), the rate of shock success at low energy was significantly higher in the tertile with highest AMSA values (T3: 38% vs T2: 15% vs T1: 5%; p<0.01). Particularly in T3, low energy was more effective than high energy shocks (38% vs 23%, p < 0.001). Conclusion This is the first study to identify a datapoint to guide decision-making with regards to defibrillation with lower energy levels. AMSA could indeed guide the selection of energy levels in order to optimize efficaciousness in restoring a perfusing rhythm while minimizing the contribution to myocardial dysfunction.

Anteroposterior Versus Anterolateral Electrode Position for Direct Current Cardioversion of Atrial Fibrillation: AMeta-Analysis of Randomised Controlled Trials.

Data regarding optimal electrode positioning for direct current cardioversion (DCCV) of atrial fibrillation (AF) has been inconsistent. This meta-analysis was conducted to systematically compare the efficacy of anteroposterior (AP) versus anterolateral (AL) electrode placement for DCCV of AF. Electronic databases were searched for randomised controlled trials (RCTs) comparing AP versus AL electrode positioning in patients undergoing DCCV for AF. Primary endpoints were first-shock success and overall DCCV success. Subgroup analysis was performed by defibrillator waveform (monophasic versus biphasic). Meta-regression analyses were performed to assess for significant moderators. Twelve (12) RCTs, including a total of 2,046 patients, met inclusion criteria. Neither first-shock success (relative risk [RR] 0.92; 95% CI 0.79-1.07; p=0.28) nor overall DCCV success (RR 1.01; 95% CI 0.96-1.05; p=0.78) were significantly different with AP versus AL electrode positioning. The mean number of shocks (mean difference [MD] 0.3, 95% CI -0.4 to 0.9), energy level of first successful shock (MD 3 joules; 95% CI -20 to 27) and cumulative energy delivered (MD 39 joules; 95% CI -168 to 246) were similar in AP versus AL arms. In subgroup analysis of six RCTs using biphasic defibrillators, improvement in first-shock success (RR 0.85; 95% CI 0.69-1.03; p=0.10) and overall DCCV success (RR 0.97; 95% CI 0.93-1.01; p=0.09) with AL electrode positioning did not reach statistical significance. Meta-regression analyses identified older age, higher body mass index, and longer AF duration as significant moderators favouring AL electrode positioning. Pooled analysis of randomised data overall does not show a significant difference in efficacy between AP versus AL electrode positioning. Meta-regression and subgroup analyses suggest that, in contemporary practice with use of biphasic defibrillators, there may be a subset of AF patients in whom AL electrode positioning improves efficacy of DCCV.

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

AimAutomated 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. MethodsTwo 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. ResultsExperiment 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. ConclusionsThere 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.

The Impact of Cardiopulmonary Resuscitation Guidelines Updates Against Out-of-Hospital Shockable Cardiac Arrest: A Population-Based Cohort Study

Background: International cardiopulmonary resuscitation (CPR) guidelines based on the best available evidence from resuscitation science have been updated since 2000. However, few nationwide population-based studies have been investigated comprehensive efficacy of those updates for out-of-hospital cardiac arrest (OHCA). Methods: From the All-Japan Utstein Registry between 2005 and 2015, we enrolled 73 578 adults who had witnessed shockable (ventricular fibrillation or pulseless ventricular tachycardia) OHCA. We examined temporal trends over eleven years (2005 on the Guidelines 2000 era, from 2006 to 2010 on the consensus on CPR and emergency cardiovascular care science with treatment recommendations [CoSTR] 2005 era, and from 2011 to 2015 on the CoSTR 2010 era). The primary end point was favorable neurological outcome (Cerebral Performance Category of 1 or 2) at 30 days after OHCA. Findings: Of 73 578 study patients, 61,080 (83%) were witnessed by bystander and 12 498 (17%) by emergency medical services (EMS) responder. After adjustment for Utstein variables, odds ratios for favorable 30-day neurological outcome increased year by year (reference, 2005): the bystander-witnessed group, 1∙19 (95% CI 1∙03-1∙37) in 2006, 2∙40 (95% CI 2∙10-2∙74) in 2010, 2∙45 (95% CI 2∙14-2∙80) in 2011 and 3∙02 (95% CI 2∙63-3∙46) in 2015; the EMS responder-witnessed group, 1∙27 (95% CI 1∙01-1∙60) in 2007, 1∙28 (95% CI 1∙02-1∙60) in 2010, 1∙54 (95% CI 1∙23-1∙94) in 2011 and 1∙58 (95% CI 1∙26-1∙99) in 2015. Similar results were seen in the subgroups receiving EMS-dispatcher CPR instruction, bystander chest compression-only CPR, early defibrillation, biphasic waveform defibrillators or advanced airway management. However, there was no evidence for any benefit from the addition of epinephrine. Interpretation: The international CPR guidelines updates for shockable OHCA had improved neurologically intact survival year by year. However, epinephrine is a topic for the future. Clinical Trial Registration Details: This study is registered with the University Hospital Medical Information Network Clinical Trials Registry, UMI09918. Funding Information: None. Declaration of Interests: We declare no competing interests. Ethics Approval Statement: A subcommittee of resuscitation science in the Japanese Circulation Society conducted this study with approval from the ethics committee at Nihon University Hospital.

Resuscitation Medicine in Undergraduate Curriculum

A fresh medical graduate posted as an intern in wards has the biggest fear of any patient needing cardiopulmonary resuscitation during his duty hours. He had listened to lectures on cardiopulmonary resuscitation (CPR) in his final year medicine posting, witnessed his seniors performing chest compressions, and also participated by doing some errand jobs (making phone calls, calling nurse, loading drugs) but he is always worried to face a similar situation all by himself as a first responder. The simulation course in CPR which is available under the newer guidelines of the National Medical Council (NMC) undergraduate curriculum is a group activity and it is very much possible that few students get left out in understanding the nuances of good CPR practice. Resuscitation medicine (RM) is a rapidly evolving area that crosses the boundaries of emergency medicine, intensive care medicine, anaesthesia, and acute medicine.1 It is the process of correcting physiological disturbances (such as lack of breathing or heartbeat) in an acutely ill patient. Resuscitation entails more than just guidelines, training centres, and public training. The clinical practice of resuscitation, whether in-hospital or out-of-hospital, has taken on a seriousness that concerns the quality of practice, speed of implementation, and an increasing realization that every one of our patients deserves only the best skill we can offer. It has evolved from the practice of barbaric methods of yelling, slapping, hanging of the victim in face-down condition, etc to the discovery of external chest compressions by William Harvey in 1628.2 The most important contribution to the field of resuscitation medicine was given by an electrical engineer William Kouwenhoven (1886–1975) by rediscovering the science of external cardiac compression by accident during his research on internal and external defibrillation. No doubt that he is remembered as the founder of modern CPR.2 Many pharmacological and device technologies were developed thereafter and integrated into resuscitation protocols, such as the use of epinephrine, calcium, lidocaine, sodium bicarbonate, defibrillation waveforms, and improved electrocardiographic monitoring. More recently, therapeutic hypothermia (TH) in which the body is cooled to between 33 and 36 °C in an effort to decrease the metabolic injury due to ischemia, emergency use of extracorporeal membrane oxygenation (ECMO) in which a pulseless person is rapidly placed on a fully artificial heart and lung machine and controlled reperfusion in which the patient receives pulsatile blood flow rather than a continuous flow to better mimic normal physiology have emerged.3 These therapeutic interventions require the earliest possible recognition of cardiac arrest with the initiation of basic protocols during the initial 3-4 minutes and decision planning for indications and contraindications of advanced techniques. The science of RM is highly subjected to the time taken to address the situation which further makes it compulsory that the education and training should be blended in the curriculum during growing years as a medical student. he first-year students while studying anatomy, physiology and biochemistry should learn about the electrical and circulatory phase of cardiac arrest, the various adverse biochemical reactions associated with arrest, and the anatomy related to efficient chest compressions and basic airway support. The progress of the student’s curriculum into pharmacology, microbiology, pathology, ophthalmology and ENT should simultaneously expose him to the pharmacology of drugs used in resuscitation, pathophysiology and molecular aspects of cardiac arrest, assessment of eye signs for brain dead patients, and the advanced airway management. During the final semesters, education should include the current protocols of CPR and defibrillation. In this way, we can achieve a trained medical graduate well versed with basic tenets of knowledge in resuscitation. The period of internship should expose him to learn advanced protocols of quality management, real-life limitations occasioned by

Recent advances in external cardiac defibrillation techniques

As an important medical electronic equipment for the cardioversion of malignant arrhythmia such as ventricular fibrillation and ventricular tachycardia, cardiac external defibrillators have been widely used in the clinics. However, the resuscitation success rate for these patients is still unsatisfied. In this paper, the recent advances of cardiac external defibrillation technologies is reviewed. The potential mechanism of defibrillation, the development of novel defibrillation waveform, the factors that may affect defibrillation outcome, the interaction between defibrillation waveform and ventricular fibrillation waveform, and the individualized patient-specific external defibrillation protocol are analyzed and summarized. We hope that this review can provide helpful reference for the optimization of external defibrillator design and the individualization of clinical application.

The shocking lack of significant increases in high sensitivity troponin values after cardioversion

Abstract Background and introduction Cardioversion is commonly used to terminate cardiac arrhythmias. Some previous reports have suggested that cardioversion results in myocardial injury as evidenced by increased levels of cardiac troponin. However, many of these studies were done years ago with less sensitive troponin assays and monophasic waveform defibrillators. Purpose To determine if external direct current (DC) cardioversion with biphasic rectilinear waveform shocks results in myocardial injury as assessed by high sensitivity cardiac troponin T (hs-cTnT) and I (hs-cTnI). Methods Patients scheduled for elective DC cardioversion for atrial fibrillation or atrial flutter were recruited. Plasma samples for measurement of hs-cTnT and hs-cTnI were obtained pre-cardioversion and as late as feasible but at least 6 hours post-cardioversion [median of 9 (7–11) hours]. Results A total of 96 patients were recruited. One patient was excluded because the pre-cardioversion sample was hemolysed. Median (25th–75th interquartile range) cumulative energy delivered was 121.6J (62.4–277.4J) and median highest energy individual shock was 121.0J (62.1–146.2J). A total of 39 (41.1%) patients received more than 1 shock, 23 (24.2%) patients received a cumulative energy of 300J or higher and 5 (5.3%) patients received a cumulative energy of 1,000J or more. The median pre-cardioversion hs-cTnT value was 11.48 (7.19–18.38) ng/L and the median hs-cTnI value was 5.1 (2.0–9.4) ng/L. Median post-cardioversion hs-cTnT value were 12.46 (7.98–20.28) ng/L and hs-cTnI value were 6.3 (3.5–10.0) ng/L. Wilcoxon-Signed ranks test showed a statistically significant change between the pre-and-post cardioversion hs-cTnT values (Z=−4.237, p<0.001) and hs-cTnI values (Z=−4.822, p<0.001). In only 5 (hs-cTnT) and 4 patients (hs-cTnI) was there an increase of >5 ng/L. There were 5 cases where the post-cardioversion values of both hs-cTnT and hs-cTnI were above the 50% reference change value. There was no relation between the change in hs-cTn values and sex, number of shocks, total energy delivered (even in those who received more than 1,000J), highest energy per shock, total current delivered, highest current delivered per shock or transthoracic impedance. Conclusion(s) There is a statistically significant but very small change in median hs-cTnT and hs-cTnI values (1 ng/L and 1.2 ng/L respectively) after DC cardioversion. The results were similar even in patients where high energy shocks were delivered and did not vary based on the pre cardioversion baseline value. Patients who have marked troponin elevations after cardioversion should be assessed for other causes of myocardial injury. It should not be assumed that they have myocardial injury from the cardioversion alone. Figure 1 Funding Acknowledgement Type of funding source: Other. Main funding source(s): Dr. Allan Jaffe has substantial research funds from both grants and private industry. Funds were used to pay for blood sample collection and analysis of high sensitivity cardiac troponin T at Mayo Clinic. Abbott Laboratories donated reagents for the high sensitivity cardiac troponin I analysis.

院内発生の妊婦心肺停止症例に対応するための体制整備(System development and simulation training for management of in–hospital maternal cardiac arrest)

要旨【目的】妊婦が心肺停止に至ったときに，母体救命のため 死戦期帝王切開PMCD（perimortem cesarean delivery）を行うことが考慮される。当院は院外症例の受け入れ体制は整っていたが，院内症例の体制整備はされておらず，心停止から5分以内にPMCDを実施することが可能な体制をつくることとした。【対象】産科病棟で発生したと想定し，問題点の抽出をした。実施場所に関して，手術室で行うには手術申込みや入室認証が必要であったため，少しでも時間を短縮させるため分娩室とした。実施までのフローシート，連絡経路も事前に作成した。PMCDの適応や効果に関して教育を行い，PMCD器材と，新生児蘇生器材とに分けて準備し，シミュレーションを行った。【結果】第1回目のシミュレーションは救急科医の到着を待って，分娩室に移動しPMCDを実施したが，実施までに14分かかった。2回目は，心肺停止を覚知後すぐに患者を分娩室に移動させPMCDを実施し，4分で行うことができた。除細動の適応波形の場合にはどうするべきか，などの新たな問題点が抽出された。【結語】院内発生の妊婦心肺停止症例では，心停止から医療従事者接触までの時間が短く救命できる可能性が高い反面，短時間でPMCD実施の決断や実行が求められるため，シミュレーショントレーニングは重要と考えられる。

Design and Construction of High-Frequency Cardiac Defibrillator for Small Animals.

The main goal of this research is to evaluate the defibrillation efficacy with the high-frequency waveform on ventricular fibrillation in small animals. A biphasic defibrillator with adjustable frequency was designed for this study. This custom-designed defibrillator can be adjusted to generate four different frequencies of 125, 250, 500, and 1000 Hz. Six rat hearts were induced VT/VF by electrical induction using the waveform of these four frequencies. Success VT/VF-induction by applying those four frequencies were recorded and observed by optical mapping. The results showed that the VT/VF-induction success rate is increasing along with higher frequencies. The VT/VF-induction success rate is 16% in 125Hz and 250 Hz, 33% in 500 Hz, and 100% in 1000 Hz with S1-S2 protocol at 100 ms coupling interval. Also, using optical mapping technique, shock-induced optical potential showed that only high-frequency waveform exhibited the largest tissue responses in the middle position of the heart. In conclusion, high-frequency (1000Hz) defibrillation waveform has the highest defibrillation efficacy comparing to other lower frequencies used in this study.

First-time evaluation of ascending compared to rectangular transthoracic defibrillation waveforms in modelled out-of-hospital cardiac arrest

Aim of the studyPrognosis in out-of-hospital cardiac arrest (OHCA) depends on cardiopulmonary resuscitation (CPR) duration. Therefore, the optimal biphasic defibrillation waveform shows high conversion rates besides low energy. Matthew Fishler theoretically predicted it to be truncated ascending exponential. We realised a prototypic defibrillator and compared ascending with conventional rectangular waveforms in modelled OHCA and CPR. MethodsApproved by the authorities, 57 healthy swine (Landrace ​× ​Piétrain) were randomised to ASCDefib (n 26) or CONVDefib (n 26). Five swine served as sham control. We induced ventricular fibrillation (VF) electrically in anaesthetised swine randomised to ASCDefib or CONVDefib and discontinued mechanical ventilation. After 5 ​min of untreated cardiac arrest, we started CPR with mechanical chest compressions and ventilation. We performed transthoracic biphasic defibrillations after 2, 4, 6 and 8 ​min CPR targeting 4 ​J/kg in either group. Depending on the randomised group, the defibrillation protocol was either three ascending followed by one rectangular waveform (ASCDefib) or three rectangular followed by one ascending waveform (CONVDefib). ResultsUnder our model-specific conditions, VF was initially terminated by 13/80 ascending waveforms and 13/79 rectangular waveforms and persistent return of spontaneous circulation was achieved in 8/26 (ASCDefib) vs. 10/26 (CONVDefib) animals. Mean current rather than waveform design was predictive for defibrillation success in a generalised linear model. ConclusionContrary to theoretical assumptions, transthoracic biphasic defibrillation with ascending waveforms is not superior to rectangular waveforms in modelled OHCA. We advocate defibrillation dosage to be guided by current, that has proven its predictive value again. Institutional protocol number84–02.04.2017.A176.

Cardioversion of Atrial Fibrillation and Flutter: Comparative Study of Pulsed vs. Low Energy Biphasic Truncated Exponential Waveforms.

Despite the widespread use of biphasic waveforms for cardioversion and defibrillation, the efficacy and safety of shocks has only been compared in a few studies. This retrospective study aims at comparing the efficacy and safety of biphasic truncated exponential (BTE) pulsed energy (PE) waveform with a BTE low energy (LE) waveform for cardioversion of atrial fibrillation (AF) and atrial flutter (AFL). The treatment energies were following an escalating protocol for PE waveform (120-200-200J in AF and 30-120-200J in AFL) and LE waveform (100-200-200J in AF and 30-100-200J in AFL). The protocol was stopped at successful cardioversion (sinus rhythm at 1 minute post-shock), otherwise after the 3rd shock. If the 3rd BTE shock failed, a monophasic shock of 360J was delivered. From May 2008 to November 2017, 193 patients (153 PE, 40 LE) were included in the study. Both groups significantly differed in a few characteristics, including chest circumference (p<0.05). After adjustment, the success rate was not significantly different for the two waveforms (94.5% PE vs 92.5% LE, Odds Ratio [95% Confidence Interval] = 0.25 [0.03-2.2]).There was no difference in safety: post-shock changes in Hsc-TnI levels were similar (p=0.25). The efficient cumulative energy was particularly related with BSA (β = 131.5, p=0.05), AF/AFL duration (β = 0.24, p=0.01) and gender (β = 61.8, p=0.05). The major clinical implications of this study concern the high success rate of cardioversion with both biphasic pulses and no superiority of LE over PE waveform with an excellent safety profile without post-shock myocardial injuries.

First-time evaluation of ascending compared to rectangular defibrillation waveforms in a real-life model of cardiopulmonary resuscitation

First-time evaluation of ascending compared to rectangular defibrillation waveforms in a real-life model of cardiopulmonary resuscitation

Ascending Defibrillation Waveform Significantly Reduces Myocardial Morphological Damage and InjuryCurrent.

This study tested the hypothesis that a biphasic defibrillation waveform with an ascending first phase (ASC) causes less myocardial damage by pathology and injury current than a standard biphasic truncated exponential (BTE) waveform in a swine model. Although lifesaving, defibrillation shocks have significant iatrogenic effects that reduce their benefit for patient survival. An ASC waveform with an 8-ms linear ramp followed by an additional positive 0.5-ms decaying portion withamplitudes of 20J (ASC 20J) and 25J (ASC 25J) was used. The control was a 25-J BTE conventional waveform (BTE25J) RESULTS: The ASC 20J and ASC 25J shocks were both successful in 6 of 6 pigs, but the BTE 25J was successful in only 6of 14 pigs (p<0.05). Post-shock ST-segment elevation (injury current) in the right ventricular electrode was significantly greater with BTE 25J than with ASC 20J and ASC 25J. With a blinded pathology reading, hemorrhage, inflammation, thrombi, and necrosis 24h post-shock were significantly greater with BTE 25J than with ASC 20J and ASC 25J. Troponin levels were also markedly lower at 3, 4, 5, and 6h post-shock. Defibrillation shocks cause electrophysiological, histological, and biochemical signs of myocardial damage and necrosis. These signs of damage are markedly less for an ASC waveform than for a conventional BTEwaveform.

Abstract 129: Effect of Defibrillation Dose and Waveform Characteristics on Defibrillation Success in Pediatric In-Hospital Cardiac Arrest

Introduction: Amplitude spectral area (AMSA) predicts successful defibrillation (DF) and return of spontaneous circulation (ROSC) in adults but has not been studied during pediatric in-hospital cardiac arrest (IHCA). Hypothesis: We characterized DF dose and AMSA during pediatric IHCA from a pediatric resuscitation quality (pediRES-Q) collaborative and hypothesized that a threshold value of AMSA could predict successful DF. Methods: Children &lt;18 years with witnessed IHCA, ventricular fibrillation (VF) as the initial rhythm, and those who had complete CPR quality metric data captured from the bedside defibrillator (ZOLL R-Series, Chelmsford, MA) were studied. Energy dose, initial AMSA ( i AMSA) and pre-shock AMSA ( p AMSA) [2.5-sec ECG window before defibrillation] for predicting DF success were calculated, together with receiver operator (ROC) curves. Successful DF (sDF) was defined as return of an organized rhythm 5 seconds after DF. Sustained ROSC was defined as &gt;20 minutes without chest compressions. Events with DF due to ventricular tachycardia, inappropriate shocks (i.e. supraventricular tachycardia, conduction block), unavailable AMSA values, and VF events using &lt;1 J/kg for DF were excluded. Results: Between 2015-2018, 34 subjects (median age 7.4 years [1.3,13.1]; median weight 19.4 kgs [8.9, 41.7]) with IHCA due to VF were enrolled. We analyzed 26 shocks in 18 children &lt; 8 years and 25 shocks in 16 children 8 to &lt;18 years. For children &lt; 8 years, the initial DF median dose/kg was 2.5 [2.3,3.3] J/kg with sDF in 14/26 (54%) shocks and sustained ROSC in 10/18 (56%) children. For those 8 to &lt;18 years, initial DF median dose/kg was 3.0 [2.5,3.4] J/kg with sDF in 10/25 (40%) shocks and sustained ROSC in 10/16 (63%). AMSA was significantly higher prior to sDF than in unsuccessful DF ( p AMSA 19.14±8.11 vs.12.0±7.38 mV-Hz, p = 0.0021; i AMSA 19.08±7.38 vs. 11.04±6.57 mV-Hz, p = 0.0053). Area under the ROC curve was 0.765 for p AMSA and 0.796 for i AMSA. Conclusions: We characterized DF dose and AMSA during pediatric IHCA with an initial rhythm of VF and found that sDF was significantly associated with AMSA &gt;19 mV-Hz. Future studies should determine the AMSA threshold that predicts sDF in children due to differences in heart size and cardiac arrest etiology.

Biphasic Waveform External Defibrillation Starting Energy and In-Hospital Cardiac Arrest Survival: Retrospective Cohort Study From the Get With the Guidelines-Resuscitation Registry

ABSTRACT Biphasic waveform defibrillators permit effective defibrillation of ventricular tachycardia and ventricular fibrillation (VT/VF) at lower energies. Little data is available on trends in th...

Association between transthoracic impedance and electrical cardioversion success with biphasic defibrillators: An analysis of 1055 shocks for atrial fibrillation and flutter.

The relevance of transthoracic impedance (TTI) to electrical cardioversion (ECV) success for atrial tachyarrhythmias when using biphasic waveform defibrillators is unknown. TTI is predictive of ECV success with contemporary defibrillators. De-identified data stored in biphasic defibrillator memory cards from ECV attempts for atrial fibrillation (AF) or atrial flutter (AFL) over a 2-year period at our center were evaluated. ECV success, defined as arrhythmia termination and ≥ 1 sinus beat, was adjudicated by 2 blinded cardiac electrophysiologists. The association between TTI and ECV success was assessed via Cochrane-Armitage trend and Spearman rank correlation tests, as well as simple and multivariable logistic regression. The influence of TTI on the number of shocks and on cumulative energy delivered per patient was also examined. 703 patients (593 with AF, 110 with AFL) receiving 1055 shocks were included. Last shock success was achieved in 88.0% and 98.2% of patients with AF and AFL, respectively. In patients with AF, TTI was positively associated with last shock failure (Ptrend =0.019), the need for multiple shocks (Ptrend <0.001), and cumulative energy delivered (ρ = 0.348; P < 0.001). After adjusting for first shock energy, 10-Ω increments in TTI were associated with odds ratios of 1.36 (95% CI: 1.24-1.49) and 1.22 (95% CI: 1.09-1.37) for first and last shock failure, respectively (P < 0.001 for both). Although contemporary defibrillators are designed to compensate for TTI, this variable continues to be associated with ECV failure in patients with AF. Strategies to lower TTI during ECV for AF may improve procedural success.

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

AimEarly 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. MethodsThis 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)). ResultsIn 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. ConclusionsAn 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.

Dynamic evaluation of myocardial dysfunction in rats after cardiopulmonary resuscitation

Objective To observe the dynamic changes of myocardial structure and dysfunction during post-resuscitation period in order to establish a rat mode of post-resuscitation myocardial dysfunction after cardiac arrest resulted from electric stimulation-induced ventricular fibrillation (VF) and cardiopulmonary resuscitation (CPR). Methods A total of 40 male Sprague-Dawley (SD) rats were randomly(random number) assigned into post-resuscitation (PR) 4 h, PR 12 h, PR 24 h, PR 72 h and sham groups. VF was induced by an alternating electric current delivered to the right ventricular endocardium and untreated for 8 min. Biphasic waveform defibrillation was attempted and mechanical ventilation was synchronized after 6 min of CPR. Myocardial function was assessed with serum myocardial enzyme activity, echocardiography, mitochondrial respiratory function and histopathologic findings at different intervals. Results Thirty-two animals were successfully resuscitated with restoration of spontaneous circulation (ROSC) in 86% (32/37)rats. Compared with sham group, severe systolic and diastolic heart failure were found at 4 h after ROSC and then gradually improved without significant difference(P>0.05) in ejection fraction at PR 72 h after ROSC was found, whereas thickened ventricular wall and increased myocardial performance index as well as interstitial proliferation were observed at 72 h after ROSC. Conclusions A rat model of post-resuscitation myocardial dysfunction after cardiac arrest resulted from electric stimulation-induced VF and CPR was successfully established. Key words: Cardiac arrest; Cardiopulmonary resuscitation; Myocardial dysfunction; Mitochondrion; Animal model

English

Ventricular fibrillation is a disorder in which present uncooperative shrivelling of the cardiac muscle of the ventricles in the mood, production them shiver rather than indenture properly. Ventricular fibrillation is the record normally recognized in cardiac trepidation patients.Two phasic defibrillation waveforms are most popularly recognized rather the effect of dismissing ventricularfibrillation (VF) than monophasic waveforms. The hypothesis phases improve the efficiency there are two phases are improved than one, this unsurprisinglyindications to the hypothesis. Our research leads to adding one additional phase to patterned hypothesis. We observed the effectiveness of 19dissimilartriphasic waveforms in chorus.We confirmed the degree of recovery, i.e., effective defibrillation, of 22 guinea livestock (825-1100 g) using single phasic, two phasic andtriphasic, defibrillation waveforms. We can control the single phase and bi phase waveforms. VF was electrically talked into twenty times per visceral and a single defibrillation challenge was prepared using a test waveform VF episode. All waveform was used to the energy prerequisite to defibrillate that bodily 55% of the time, by means of a biphasic waveform as acontrol.

The effects of second and third phase duration on defibrillation efficacy of triphasic rectangle waveforms

BackgroundBiphasic waveforms are superior to monophasic waveforms for the termination of ventricular fibrillation (VF). However, whether triphasic waveforms are more effective than biphasic ones is still controversial. In the present study, we investigated the effects of second and third phase duration of triphasic rectangle waveform on defibrillation efficacy in a rabbit model of VF. MethodsVF was electrically induced and untreated for 30s in 20 New Zealand rabbits. A defibrillatory shock was applied with one of the 7 waveforms: 6 triphasic rectangle waveforms and a biphasic rectangle waveform. The triphasic waveforms had identical first duration but with different second and third phase durations. A 5 step up-and-down protocol was utilized for determining the defibrillation threshold (DFT). After a 5min interval, the procedure was repeated. A total of 35 cardiac arrest events and defibrillations were investigated for each animal. ResultsTwo triphasic waveforms with identical first and second phase duration but shorter third phase duration had significantly lower DFT energy than biphasic waveform (0.57±0.18J vs. 0.80±0.28J, p=0.001; 0.60±0.18J vs. 0.80±0.28J, p=0.003). However, no statistical difference in DFT energy was observed between the two triaphsic waveforms that had identical phase duration but different voltages (0.57±0.18J vs. 0.60±0.18J, p=0.638). ConclusionsPhase durations played a main role on defibrillation success for triphasic rectangle waveforms. The optimal triphasic rectangle waveforms that composed of identical second and first phase durations but with shorter third pulse were superior to biphasic rectangle waveform for ventricular defibrillation.