Ascending Defibrillation Waveform Significantly Reduces Myocardial Morphological Damage and Injury Current

Methods of Using a Manual Defibrillator during Simultaneous Cardiac Arrest in Two Patients-Analysis of the Actions of Emergency Medical Response Teams during the Championships in Emergency Medicine

Background/Objectives: Conducting advanced resuscitation requires medical personnel to carry out appropriately coordinated actions. Certain difficulties arise when it becomes necessary to conduct cardiopulmonary resuscitation (CPR) on two patients at the same time. The aim of this paper was to assess the actions of teams participating in emergency medicine championships in tasks related to simultaneous cardiac arrests in two patients. Methods: The study was conducted on the basis of an analysis of assessment cards for tasks carried out during the 'International Winter Championships in Emergency Medicine'. Three-person medical response teams (MRTs), with the support of two people, had the task of conducting advanced resuscitation on an adult and child simultaneously. The tasks were prepared and developed by European Resuscitation Council (ERC) instructors. Results: The study showed that teams used four methods of checking heart rhythm and performing defibrillation during CPR-using paddles only, using paddles and self-adhesive electrodes, using paddles and a three-lead ECG and using two pairs of self-adhesive electrodes. Teams performing cardiopulmonary resuscitation using paddles and a three-lead ECG performed significantly more actions incorrectly than other teams-in part due to the fact that they incorrectly interpreted which patient's heart rhythm was displayed on the defibrillator screen. The effectiveness of the remaining methods was similar for most of the actions. The CPR method using two pairs of electrodes enabled personal safety to be maintained to the significantly highest percentage during defibrillation. Conclusions: The study demonstrated that the need to conduct CPR on two patients at the same time, irrespective of the method used, caused MRT members considerable difficulties in correctly conducting some of the actions. The method of assessing heart rhythm using paddles and a three-lead ECG should not be used. The study showed that the optimal method of CPR in use appears to be the method using two pairs of adhesive electrodes-it provided, among other things, the significantly highest percentage of safely conducted defibrillation.

Analysis of Emergency Medical Response Team Performance during the International Winter Championships in Emergency Medicine

Background and Objectives: Conducting advanced life support (ALS) according to the guidelines of the European Resuscitation Council (ERC) requires medical personnel to implement the appropriate emergency actions. In particular, these actions include chest compressions, airway management, artificial ventilation, defibrillation and the administering of medicines. An appropriate training system enables members of medical response teams (MRT) to acquire the essential knowledge and skills necessary to correctly conduct cardiopulmonary resuscitation (CPR). One way to improve the quality of interventions by MRT personnel is participation in emergency medicine championships. Materials and Methods: The research analysed assessment cards for tasks carried out during the International Winter Championships in Emergency Medicine in the years 2013–2020. The assessed tasks were prepared and led by European Resuscitation Council instructors of advanced life support. During ten-minute scenarios of simulated sudden cardiac arrest (SCA) in adults, the judges assessed the compliance of procedures with current ERC guidelines. This research analysed the performance of 309 teams from Poland made up of paramedics from medical response units from all over the country. Results: In most cases, the study showed significant differences in the percentage of correctly performed procedures between years. Most often, the highest percentage of correctly performed procedures was recorded in 2019 and 2020. The lowest percentage of correctly performed procedures was most often recorded in 2013. In subsequent years, the percentage of use of tracheal intubation decreased (from 54.76% to 31.25%) in favour of an increase in the use of supraglottic airway device SAD (from 35.71% to 59.38%). Conclusions: The research has shown that in subsequent years of the Championships, the quality of the majority of assessed procedures carried out by members of MRT gradually improved. The research authors also observed that in subsequent years, the percentage of intubations decreased in favour of SAD.

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.

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

Aim of the study

Prognosis 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.

Methods

Approved 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).

Results

Under 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.

Conclusion

Contrary 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 number

84–02.04.2017.A176.