Outcome after pre-hospital cardiac arrest in accordance with underlying cause

Abstract

Aim

In terms of treatment options, the underlying cause of out-of-hospital cardiac arrest (OHCA) has an impact on survival. This study aimed to examine the frequencies of different causes of OHCA and their outcomes using data from a national resuscitation registry.

Methods

All pre-hospital cardiopulmonary resuscitations (CPR) documented in the German Resuscitation Registry between 2007 and 2017 were retrospectively investigated with regard to cause of cardiac arrest, return of spontaneous circulation (ROSC), and hospital discharge rate with good neurological outcome. To avoid selection bias, only rescue services with a return rate in the form ‘further clinical treatment’ of >30% were included, this resulted in a total return rate of 84% of the included data.

Results

In total, 33,772 patients were included. The most common causes of OHCA were cardiac events (62.2%), hypoxia (11.1%) and trauma (3.2%), in 17.2% no or unknown cause were documented. Overall, 44.8% of patients achieved ROSC, 13.1% of patients were discharged alive from hospital and 68.3% of these were in good neurological condition (9.0% of all patients). ROSC rates differed between 8.9% (sudden infant death syndrome) and 64.4% (intracranial bleeding), while discharge rates with good neurological outcome ranged between 0.9% (sepsis) and 14.0% (intoxication).

Conclusion

The most common causes of OHCA are cardiac events and hypoxia. Depending on the underlying cause, outcome after pre-hospital CPR varies widely with a survival rate with good neurological outcome ranging from 0.9 to 14%.

Introduction

Out-of-hospital cardiac arrest (OHCA) is a relevant issue in the care of pre-hospital emergency services. Ten years ago, approximately 275,000 of OHCA cases per year in Europe (estimated population in 2004: 729 million) were assumed,¹ with estimates of current studies suggesting an incidence of 84.0–87.4 cases/100,000 inhabitants per year.2, 3 By extrapolation, this would represent approximately 640,000 OHCA cases each year in Europe (estimated population in 2018: 742 million). Cardio-pulmonary resuscitation (CPR) can be performed by laymen or pre-hospital rescue services at an estimated average of 49 cases/100,000 inhabitants in the European Union.² However, despite intensive scientific research and various health promotion campaigns throughout different countries, OHCA survival has barely changed over the last 10 years and still approximates 10%.²

In addition to high-quality performance of CPR as well as early defibrillation (if indicated) as actions of basic life support, advanced cardiac life support includes the identification and treatment of potentially reversible causes.⁴ For this purpose, the underlying pathology should be identified and treated as far as possible. For example, the cause of OHCA can be a cardiac event, trauma, metabolic or respiratory disorders, intoxication, stroke (ischaemic or haemorrhagic) or hypothermia. The knowledge of the cause and the associated possibility of therapy could have a relevant and profound influence on the patient’s chances of survival.

While there are various prevalence and cross-descriptive studies on cardiac or trauma-associated OHCA and their outcomes,⁵ other and less common causes of OHCA have received little attention. Concerning the area of in-hospital resuscitation, Wallmüller et al. compared the frequencies of underlying aetiology in cardiac arrests and demonstrated that this had a relevant impact on the outcome.⁶ To date, equivalent detailed investigations for the pre-hospital setting are missing.

The aim of this study was therefore to examine the frequencies of different causes of OHCA and the outcomes depending on the underlying cause, based on a national registry dataset for pre-hospital resuscitation.