Defibrillation bei einem präklinischen Herz-Kreislauf-Stillstand: Konversionsraten und Rezidivhäufigkeiten in der Frühphase der Reanimation durch den Rettungsdienst

Background: According to WHO, the most common cause of death worldwide is ischemic heart disease. For out-of-hospital-cardiac-arrest (OHCA) due to ventricular fibrillation (VF) guidelines recommend early defibrillation followed by chest compressions for two minutes before analyzing shock success. If rhythm analysis reveals VF again, it is obscure whether VF persisted or reoccurred within the two-minutes-cycle of chest compressions after successful defibrillation. This thesis is thematically dedicated to prehospital defibrillation performed during resuscitation by emergency medical services in the context of out-of-hospital cardiac arrest. Specifically, the defibrillation success and the point in time of a possible recurrence of ventricular fibrillation in the time interval immediately after defibrillation until the next cardiac rhythm analysis was part of the investigation. Methods: The analysis included all cases of OHCA presenting with initial ventricular fibrillation (VF) rhythm at arrival of ALS-ambulance (Marburg-Biedenkopf-County, 246.648 inhabitants) from January 2014 to March 2018. Three independent investigators analyzed corpuls3-ECG-recordings. ECG-data from CPR-beginning until four minutes after the third shock was included. High-pass filters were used for analysis. VF termination was defined as the absence of a VF-waveform within 5 s of shock delivery. VF recurrence was defined as the presence of a VF-waveform in the interval 5 s post shock delivery. Formal processing by an ethics committee was not required. Results: 185 biphasic shocks of 82 patients were included and analyzed. 74.1% (n = 137) of all shocks terminated VF, but VF recurred in 81% (n = 111). The median (IQR) time of VF-recurrences was 27 s (13.5 s/80.5 s) after shock. 51.4% (n = 57) of VF-recurrence occurred in the interval 5-30 s after shock, 13.5% (n = 15) VF-recurrence occurred 31-60 s after shock, 21.6% (n = 24) of VF-recurrence occurred 61-120 s after shock, 13.5% (n = 15) of VF-recurrence occurred 121-240 s after shock. Discussion and Conclusion: In the study underlying this thesis, the rate of successful termination of ventricular fibrillation and the occurrence and point in time of recurrences of ventricular fibrillation in patients with out-of-hospital cardiac arrest and initially shockable cardiac rhythm on arrival of the emergency medical services, were investigated. Although VF was terminated by defibrillation in 74.1%, VF recurred in 81% subsequent to the chest compression interval. The majority of refibrillations occurred in the first 30 seconds after the shock (51.4%). There are numerous studies in the literature on various topics related to defibrillation, but just a few comparable studies examining cardiac rhythm after successful defibrillation during ongoing chest compressions until the next rhythm analysis. The results of the study underlying this thesis, may support the discussion in favor of earlier antiarrhythmic drug administration and rhythm analysis to prevent recurrence of ventricular fibrillation. Thus, VF reappears frequently and early. It is unclear to which extend chest compressions influence VF-relapse. Further studies need to re-evaluate the algorithm, timing of antiarrhythmic therapy or novel defibrillation strategies to minimize refibrillation during shockable OHCA.