Rhythm changes during resuscitation from ventricular fibrillation in relation to delay until defibrillation, number of shocks delivered and survival

doi:10.1016/S0300-9572(96)01064-7

Resuscitation

Volume 34, Issue 1, February 1997, Pages 17-22

https://doi.org/10.1016/S0300-9572(96)01064-7 Get rights and content

Abstract

Aim: To describe rhythm changes during the initial phase of resuscitation from ventricular fibrillation in relation to the interval between collapse and defibrillation, to survival and to bystander-initiated cardiopulmonary resuscitation (CPR). Patients: All patients who suffered out-of-hospital cardiac arrest between 1980 and 1992, who were reached by the emergency medical service system (EMS), in whom resuscitation attempts were initiated and who were found in ventricular fibrillation. Results: In all, 1216 patients were included in the study. Among patients who converted to a pulse-generating rhythm after the first defibrillation (n=119) were 56% discharged from hospital as compared with 6% among patients who converted to asystole. The corresponding figures after the third defibrillation were 49% and 2%, respectively, and after the fifth defibrillation 28% and 7%, respectively. Among patients in whom the first defibrillation took place less than 5 min after collapse, 28% directly converted to a pulse-generating rhythm as compared with 3% when the first defibrillation took place 12 min or more after collapse. Conclusion: Among patients who suffer out-of-hospital cardiac arrest and are found in ventricular fibrillation, there is a strong relationship between survival and initial rhythm changes after defibrillation. These rhythm changes are directly related to the interval between collapse and the first defibrillation.

Introduction

Among patients who suffer out-of-hospital cardiac arrest and are found in ventricular fibrillation, various factors associated with survival have been described. The most important seem to be the interval between collapse and defibrillation and whether a bystander had initiated cardiopulmonary resuscitation (CPR) prior to the arrival of the ambulance crew 1, 2, 3. However, the exact relationship between rhythm changes in the initial phase of resuscitation and survival, as well as the relationship between these rhythm changes and the interval between collapse and defibrillation, are less well described. This study is aimed at further evaluating these questions.

Section snippets

Patients and methods

Target area: the city of Göteborg has an area of 449 km². Target population: the city of Göteborg has 434 000 inhabitants. Of these, 48% are men. Time of inclusion: 1 October 1980 to 31 December 1992. Organisation and equipment: all emergency patients arrived at the two city hospitals (Sahlgrenska hospital and Östra hospital). All ambulances were dispatched according to a two-tiered system; i.e. for each call judged as a life-threatening condition, a mobile coronary care unit, if available, and

Statistical methods

Pitman's nonparametric test was used. In the evaluation of dichotomous variables, Fisher's exact test, which is a special form of Pitman's test, was used. Two-sided tests were used. A P-value less than 0.05 was regarded as significant.

Results

In all, 3434 patients were found in cardiac arrest outside hospital during the inclusion period, among whom 1360 (40%) had a ventricular fibrillation as the initial arrhythmia. Among these 1360 patients, 1216 cases (89%) were analysed in detail with regard to rhythm changes in the initial phase. In Table 1, these 1216 patients are compared with those 144 patients in whom information about rhythm changes was missing with regard to various factors at resuscitation and survival. No significant

Discussion

The majority of deaths in ischaemic heart disease occur outside hospital and are mainly caused by ventricular fibrillation [5]. Many of these patients can be successfully resuscitated and the proportion of successful cases are increasing [4]. Various factors of ultimate importance for the chance of survival have been defined. The most important appear to be the interval between collapse and the first defibrillation and whether a bystander initiated CPR prior to the arrival of the ambulance crew

Limitations

This study was performed over a long time period during which treatment routines have changed. Thus, semiautomatic defibrillators have been introduced and the proportion of patients given medication has increased. One cannot exclude the possibility that such factors might have influenced the results. However, this is a dilemma that we always have to face when doing long-term surveys.

Furthermore, information with regard to the various rhythms being observed after defibrillation was missing in

Conclusion

Survival among patients with out-of-hospital cardiac arrest found in ventricular fibrillation on the arrival of the ambulance crew is directly related to the rhythm being observed after the first defibrillation. Rhythm changes, as well as survival in relation to rhythm changes, are related not only to the number of shocks delivered prior to the observation but also to the interval between collapse and the first defibrillation.

References (12)

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