Elsevier

Resuscitation

Volume 170, January 2022, Pages 178-183
Resuscitation

Short paper
Aetiology of resuscitated out-of-hospital cardiac arrest treated at hospital

https://doi.org/10.1016/j.resuscitation.2021.11.035Get rights and content

Abstract

Introduction

Precipitating aetiology of out-of-hospital cardiac arrest (OHCA), as confirmed by diagnostic testing or autopsy, provides important insights into burden of OHCA and has potential implications for improving OHCA survivorship. This study aimed to describe the aetiology of non-traumatic resuscitated OHCAs treated at hospital within a local health network according to available documentation, and to investigate differences in outcome between aetiologies.

Methods

Observational retrospective cohort study of consecutive OHCA treated at hospital within a local health network between 2011–2016. Cases without sustained ROSC (≥20 minutes), unverified cardiac arrest, and retrievals to external acute care facilities were excluded. A single aetiology was determined from the hospital medical record and available autopsy results. Survival to hospital discharge was compared between adjudicated aetiologies.

Results

In the 314 included cases, distribution of precipitating aetiology was 53% cardiac, 18% respiratory, 3% neurological, 6% toxicological, 9% other, and 11% unknown. A presumed cardiac pre-hospital diagnosis was assigned in 235 (84%) cases, 20% of which were incorrect after exclusion of unknown cases. Rates of survival to hospital discharge varied significantly across aetiologies: cardiac 64%, respiratory 21%, neurological 0%, toxicological 58%, other 32% (p < 0.001). A two-fold difference in survival was observed between cardiac and non-cardiac aetiologies (64% versus 29%, excluding unknown, p < 0.001).

Conclusions

Non-cardiac aetiologies represented a substantial burden of resuscitated OHCA treated at hospital within a local health network and were associated with poor outcome. The results confirmed that true aetiology was not evident on initial examination in 1 in 5 cases with a pre-hospital cardiac diagnosis.

Introduction

In Australia there are over 26,600 out-of-hospital cardiac arrests (OHCA) each year and although survival rates are improving, in-hospital mortality remains high.1., 2. A key to improving survival in successfully resuscitated patients is rapid identification and reversal of any ongoing precipitating pathophysiology. Aetiology is typically reported in the literature as presumed cardiac and obvious non-cardiac, or medical and non-medical, based on prehospital assessment by emergency medical services (EMS).3., 4. However, in the absence of obvious causes such as trauma, homicide, suicide, or obvious drug overdose, EMS-based assessments only represent preliminary diagnoses that may not reflect true aetiology. An autopsy study of presumed cardiac OHCAs aged < 40 years confirmed a non-cardiac diagnosis in 39% of cases,5 which highlights the importance of autopsy or further in-hospital investigations for the determination of aetiology. Population-based autopsy studies suggest that 40% of sudden cardiac deaths (SCD) are caused by non-cardiac aetiologies,6., 7. but few studies have reported on aetiology as confirmed by in-hospital investigations in the minority of OHCAs achieving sustained return of spontaneous circulation (ROSC).8., 9., 10. In addition, information on frequency and outcome after non-cardiac OHCAs is lacking because these cases are routinely excluded from many investigations due to low perceived survival and broad diagnostic heterogeneity. This study aimed to describe the characteristics and outcome of non-traumatic resuscitated OHCAs treated at hospital within a local health network according to precipitating aetiology.

Section snippets

Study design and setting

This is a retrospective observational cohort study of the Northern Adelaide Local Health Network (NALHN) OHCA registry, which includes all OHCAs age ≥ 18 years treated at either of the two public teaching hospitals within NALHN.11 OHCA was defined as absence of signs of circulation requiring chest compressions or external defibrillation in individuals who did not occupy an emergency department (ED) or inpatient bed.12 We identified all adult, non-traumatic OHCAs with sustained ROSC (≥20mins)

Results

From 2011-2016, 393 OHCAs were treated at a NALHN hospital. After excluding 42 without sustained ROSC, 22 with ROSC pre-EMS arrival, 11 retrieved to an external acute care facility, and 4 likely syncopal events, 314 were included in the final analysis.

Fig. 1 depicts the distribution of precipitating aetiology, identified as cardiac in 53% of cases (60% of cases with known aetiology), 18% respiratory, 3% neurological, 6% toxicological, 9% other, and 11% unknown. Within sub-categories, 59% of

Conclusion

Our study highlights the diversity of precipitating aetiology in patients with non-traumatic resuscitated OHCA treated at hospital within a local health network. Adjudicated non-cardiac aetiologies were predominately of respiratory origin, represented 40% of the cohort, and were associated with poorer outcome compared with cardiac-related OHCA. EMS-based diagnoses underestimated the burden of non-cardiac OHCA. Our results emphasise the importance of standardised criteria for determining

CRediT authorship contribution statement

M.R. Wittwer: Conceptualization, Methodology, Investigation, Formal analysis, Writing – original draft. C. Zeitz: Supervision, Writing – review & editing. J.F. Beltrame: Supervision, Writing – review & editing. M.A. Arstall: Conceptualization, Supervision, Writing – review & editing.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

The authors would like to acknowledge the University of Adelaide statistical support provided by the Data, Design and Statistics Service of Adelaide Health Technology Assessment, and would like to thank the registry staff at SA Ambulance for their assistance.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

References (22)

Cited by (4)

  • In-hospital mode of death after out-of-hospital cardiac arrest

    2022, Resuscitation Plus
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    Extracorporeal cardiopulmonary resuscitation (ECPR) is not available within the current setting, but our results highlight the importance of such an intervention given that almost two thirds of these patients had a potentially reversible precipitating cardiac aetiology. WLST for neurological and non-neurological reasons occurred at a lower rate than reported by Kempster et al.21 we also reported a slightly lower prevalence of cardiac aetiology and higher prevalence of respiratory aetiology in these patients, which is consistent with a high rate of respiratory OHCA in our cohort.22 Consistent with previous literature, we found that neurological injury was the leading mode of death in OHCAs surviving to hospital admission, irrespective of precipitating aetiology.8,9,11,23

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