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The refibrillation was a frequent event in out-of-hospital cardiac arrest (OHCA). The number of recurrences of ventricular fibrillation (VF) is in inverse relationship with survival. In this article we discuss about causes and mechanism of refibrillation. The amiodarone and new technical solution (defibrillators that may allow continuous monitoring of the heart rhythm, while chest compressions continue and recommend defibrillation when refibrillation occurs) are promising new strategy to improve outcome of OHCA and recurrent VF

In this thesis, we performed analyses on basic life support, AED (automated external defibrillator) use by first responders (police, fire-fighters, and citizen-responders), and advanced life support by emergency medical services (EMS) in out-of-hospital cardiac arrest (OHCA). We studied the proportion of shockable initial rhythm over 10 years and showed that this proportion declined during the total study period, and remained stable when limiting the analysis to the last five years. We assessed the clinical benefit of the new AED algorithm cprINSIGHT which can analyze the heart rhythm during chest compressions. We showed that cprINSIGHT could make a shock/no-shock decision with high sensitivity (96%) and high specificity (98%) and led to a higher chest compression fraction and shorter pre-shock pauses compared to conventional AEDs. We gained more insight into patients transported without ROSC and showed that in this patient population the survival rate declined when time-on-scene before transport increased. We showed that in patients with prehospital ROSC, survivors had a significantly shorter time-to-ROSC compared to non-survivors and calculated that the time point for the decision to transport appears to be between 8 and 15 minutes after EMS arrival. We explored EMS decision-making on scene and found that known factors such as age, OHCA location, witnessed status and first rhythm only explained 36% of the variance in the decision to transport and other factors related to the patient, local circumstances, the paramedic, and the structure of the organization were identified as important additional themes contributing to the decision to transport a patient with ongoing CPR.

In out-of-hospital cardiac arrest (OHCA), the main predictor of survival is ventricular fibrillation (VF). When a shock with an automatic external defibrillator (AED) or manual defibrillator is given, survival from OHCA can be more than 60%. In the absence of VF survival is poor, less than 5%. Worldwide, it has been observed that the incidence of VF is declining. In the research described in this thesis, we investigated the possible causes of the decrease in incidence of patients with VF. Without bystander CPR, ventricular fibrillation slowly transitions into asystole. A faster transition from ventricular fibrillation to asystole caused by medication use such as beta blockers might explain part of the decline. However, we did not find any indication in our study that ventricular fibrillation deteriorates faster into asystole, nor that medication use affects the VF signal in a clinical significant way. However, we did observe that the VF signal is affected by a myocardial infarction, this might be used as a marker early in the treatment of OHCA. We also observed that OHCA patients nowadays are older, are more often at home at time of the OHCA and have more underlying diseases compared to patients in public places. Outcome in these patients at home is poor, but this is due to unfavorable OHCA characteristics; in patients at home, OHCA is often unwitnessed, without bystander CPR and with little AED use. AED programs targeting residential areas are essential to improve the survival of patients at home.

Early defibrillation is one of the major determinants of survival in out-of-hospital cardiac arrest (OHCA). To achieve early defibrillation, public access defibrillation programs have been implemented. To address the need for early defibrillation, also in residential areas, a dispatcher driven alert system has been implemented that uses text messages to direct trained lay rescuers (text message responders) with automated external defibrillators (AEDs) to OHCA patients. The first part of this thesis focuses on the evaluation of the text message alert system. We found that this system contributes to earlier defibrillation, a higher percentage of bystander CPR and improved survival rates in OHCA patients in residential areas. Since the introduction of the text message alert system, lay rescuers are more often involved in resuscitation attempts. Resuscitation attempts are stressful events and may lead to post-traumatic stress disorder (PTSD). We investigated the short-term psychological impact and PTSD-related symptoms in text message responders who provided assistance in an OHCA. No responders showed PTSD-related symptoms, even if they perceived severe short-term psychological impact. Since the introduction of the text message alert system, AED use in OHCAs almost tripled. With increasing use of AEDs, reports of AED failure also increased. However, in most cases the origin of AED failure is unknown. In this thesis, we describe how often AEDs are failing and whether this has a device-related or operated-related cause. We found that errors associated with AED use are rare and if they do occur, are mainly related to the operator and circumstances of use.

Important factors in a successful resuscitation are optimal chest compression rate of 100/min, a compression depth of 5 cm and minimization of pauses in chest compressions. This constitutes ‘high quality’ CPR. The first part of this thesis focuses on assessing this quality and how feedback devices may improve the quality. We found that the force to compress the recommended 5 cm is highly variable, difficult to achieve and can benefit from the use of feedback devices. The second part of this thesis studies the outcome of resuscitation attempts after out-of-hospital cardiac arrest (OHCA). We showed that the survival rate has increased during the study period covered in this thesis and demonstrated the importance of automated external defibrillators (AEDs) to increase survival. We also showed that resuscitation parameters (i.e. presence of shockable initial rhythm and time to connection of a defibrillator device) and not pre-OHCA comorbidity, determine outcome after OHCA in older patients. Resuscitation parameters are, however, unknown in advance and therefore cannot be taken into account when discussing advance care planning. Resuscitation can only be considered successful if the survivor has an acceptable quality of life and has no impaired cognitive function. We showed that the great majority of survivors were independent in daily life and gave their quality of life a value of ≥6. While older persons had a lower probability of survival, their quality of life is good and comparable to a Dutch reference population of the same age.