Elsevier

Resuscitation

Volume 85, Issue 11, November 2014, Pages 1623-1628
Resuscitation

Clinical paper
The effect of time to defibrillation and targeted temperature management on functional survival after out-of-hospital cardiac arrest

https://doi.org/10.1016/j.resuscitation.2014.07.010Get rights and content

Abstract

Background

Cardiac arrest physiology has been proposed to occur in three distinct phases: electrical, circulatory and metabolic. There is limited research evaluating the relationship of the 3-phase model of cardiac arrest to functional survival at hospital discharge. Furthermore, the effect of post-cardiac arrest targeted temperature management (TTM) on functional survival during each phase is unknown.

Objective

To determine the effect of TTM on the relationship between the time of initial defibrillation during each phase of cardiac arrest and functional survival at hospital discharge.

Methods

This was a retrospective observational study of consecutive adult (≥18 years) out-of-hospital cardiac arrest (OHCA) patients with initial shockable rhythms. Included patients obtained a return of spontaneous circulation (ROSC) and were eligible for TTM. Multivariable logistic regression was used to determine predictors of functional survival at hospital discharge.

Results

There were 20,165 OHCA treated by EMS and 871 patients were eligible for TTM. Of these patients, 622 (71.4%) survived to hospital discharge and 487 (55.9%) had good functional survival. Good functional survival was associated with younger age (OR 0.94; 95% CI 0.93–0.95), shorter times from collapse to initial defibrillation (OR 0.73; 95% CI 0.65–0.82), and use of post-cardiac arrest TTM (OR 1.49; 95% CI 1.07–2.30). Functional survival decreased during each phase of the model (65.3% vs. 61.7% vs. 50.2%, P < 0.001).

Conclusion

Functional survival at hospital discharge was associated with shorter times to initial defibrillation and was decreased during each successive phase of the 3-phase model. Post-cardiac arrest TTM was associated with improved functional survival.

Section snippets

Background/introduction

Every year in North America, there are over 400,000 out-of-hospital cardiac arrests (OHCA) with a survival rate of 5–10%.1, 2 The probability of survival from OHCA decreases from the time of collapse to emergency medical service (EMS) intervention, however, the exact relationship between time and survival is not known. It has been proposed that cardiac arrests transition through three distinct phases of pathophysiology: electrical phase (<4 min), circulatory phase (4–10 min) and metabolic phase

Study design

This was a retrospective, observational study using data from the Toronto Regional RescuNet Epistry database, based upon the Resuscitation Outcomes Consortium (ROC) Epistry-Cardiac Arrest database, whose methods have been described previously.9 ROC Epistry-Cardiac Arrest is a prospective population based registry of consecutive EMS attended out-of-hospital cardiac arrests.9 The Toronto Regional RescuNet site contains OHCA from rural and urban regions in southern Ontario, a population of over

Results

From January 1, 2007 to April 30, 2013, there were a total of 20,165 adult OHCA treated by EMS personnel. Of these patients, 871 were eligible for post-cardiac arrest TTM and met the study inclusion criteria (Fig. 1). There were 622 (71.4%) patients who survived to hospital discharge and of these patients, 487 (78.1%) had a good functional survival (mRS 0–3).

Clinical characteristics of patients with good functional survival and poor functional survival at hospital discharge are reported in

Discussion

In our study, the use of TTM was associated with overall improved functional outcome, and this effect was dependent upon the time of initial defibrillation. These findings align with the initial 3-phase model of cardiac arrest proposed by Weisfeldt and Becker.3 In this model, the authors proposed that cardiac arrest treatment should be tailored to each specific time-sensitive phase of cardiac arrest physiology. Furthermore, they suggested that once a patient had been in cardiac arrest for

Limitations

Although the data presented was derived from a large population based data set, there were several limitations that must be considered when interpreting the results. As with other retrospective observational studies, there was a risk of measurement bias in data collection, however, this risk was minimized with the use of trained data guardians, standardized data definitions and abstraction instructions, computerized logic and error checks at point of data entry, and random re-abstraction for

Conclusion

In this study, longer delays from the time of collapse to initial defibrillation resulted in both decreased survival and good functional outcome at hospital discharge in patients resuscitated from OHCA. However, the use of TTM was associated with improved functional survival and its therapeutic effect was more pronounced in patients with prolonged times to initial defibrillation.

Conflict of interest statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

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    A Spanish translated version of the summary of this article appears as Appendix in the final online version at http://dx.doi.org/10.1016/j.resuscitation.2014.04.017.

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