Comparing the prognosis of those with initial shockable and non-shockable rhythms with increasing durations of CPR: Informing minimum durations of resuscitation

doi:10.1016/j.resuscitation.2016.01.021

Resuscitation

Volume 101, April 2016, Pages 50-56

https://doi.org/10.1016/j.resuscitation.2016.01.021 Get rights and content

Abstract

Aim

There is little data to inform the appropriate duration of resuscitation attempts for out-of-hospital cardiac arrest (OHCA). We assessed the relationship of elapsed duration since commencement of resuscitation and outcomes, highlighting differences between initial shockable and non-shockable rhythms.

Methods

We examined consecutive adult non-traumatic EMS-treated OHCA in a single health region. We plotted the time-dependent accrual of patients with ROSC, as well as dynamic estimates of outcomes as a function of duration from commencement of professional resuscitation, and compared subgroups dichotomized by initial rhythm. Logistic regression tested the association between time-to-ROSC and outcomes.

Results

Of 1627 adult EMS-treated cases of OHCA, 1617 patients were included; 14% survivors and 10% with favorable neurological outcomes. Time-to-ROSC (per minute increase) was independently associated with survival in those with initial shockable (aOR 0.95, 95% CI 0.92–0.97) and non-shockable (aOR 0.83; 95% CI 0.78–0.88) rhythms. Similar associations were seen with favorable neurologic outcome. The elapsed duration at which the probability of survival fell below 1% was 48 and 15 min in the shockable and non-shockable groups, respectively. Median time-to-termination of resuscitation was 36 and 26 min in the shockable and non-shockable groups, respectively.

Conclusion

The subgroup of initial shockable rhythms showed a less pronounced association of time-to-ROSC with outcomes, and demonstrated higher resilience for neurologically intact survival after prolonged periods of resuscitation. This data can guide minimum durations of resuscitation, however should not be considered as evidence for termination of resuscitation as survival in this cohort may have been improved with longer resuscitation attempts.

Introduction

Out-of-hospital cardiac arrest (OHCA) is common; emergency medical services (EMS) in the United States attend 134 cases per 100,000 adult citizens annually,¹ yielding survival rates between 3 and 16%.² Despite this, although termination of resuscitation (TOR) rules may assist with certain patient subgroups, data outlining the appropriate duration of resuscitation prior to termination of efforts are lacking for both pre-hospital and emergency department clinicians.3, 4 Previous data has demonstrated that an initial shockable rhythm is a predictor of survival,2, 5 however, it is unclear if initial rhythm continues to impact the probability of a good outcome after prolonged durations of resuscitation, and whether initial rhythm should influence the duration of resuscitation.

The primary objective of this study was to assess the relationship between clinical outcomes and the elapsed duration since commencement of professional resuscitation, comparing differences between those with initial shockable and non-shockable rhythms. We hoped to inform decisions regarding the optimal duration of resuscitation efforts and to explore whether this should be influenced by initial cardiac rhythm. In addition, we sought to describe the characteristics of patients with favorable outcomes who achieved return of spontaneous circulation (ROSC) after prolonged resuscitations, and the elapsed duration beyond which the point estimate for the probability of survival declined to below 1%.

Section snippets

Methods

The institutional review boards and affiliated ethics committees of Providence Health Care, the University of British Columbia, and Vancouver Coastal Health approved this study.

Characteristics of study subjects

Between September 2007 and December 2011, there were 2419 cases of OHCA in our region. Patients not treated by EMS (n = 775), those aged <18 years (n = 17), and those in whom outcomes were unavailable due to missing identifiers (n = 10) were excluded, leaving a study cohort of 1617 patients. Agreement for CPC score and dichotomous neurological outcome at hospital discharge was excellent with kappa values of 0.95 (95% CI 0.89–1.00) and 1.00 (95% CI 0.96–1.00), respectively.

Full cohort

Table 1 describes patient

Discussion

We examined 1617 consecutive EMS-treated OHCA patients in a single region, combining detailed pre-hospital data with reliable outcomes at hospital discharge. Overall, outcomes were positive in comparison to other regions.² Similar to other studies, 12, 13, 14, 15, 16 we found that shorter time-to-ROSC was independently associated with survival and neurological outcomes. Although the proportion of patients with favorable neurological outcomes achieving ROSC prior to incremental time junctures

Conclusions

Although both subgroups of shockable and non-shockable initial rhythms demonstrated an independent association of time-to-ROSC and outcomes, this association was less pronounced in patients with initial shockable rhythms indicating a higher resilience for positive outcomes after prolonged durations of CPR. Resuscitation of patients with initial shockable rhythms continued to yield neurologically intact survivors until 47.5 min; among those with non-shockable initial rhythms the longest

Conflict of interest statement

None declared.

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^☆: A Spanish translated version of the abstract of this article appears as Appendix in the final online version at http://dx.doi.org/10.1016/j.resuscitation.2016.01.021.

^☆☆: A portion of this data was presented on November 15, 2014 at the American Heart Association Resuscitation Science Symposium in Chicago, IL.

View full text

Clinical paperComparing the prognosis of those with initial shockable and non-shockable rhythms with increasing durations of CPR: Informing minimum durations of resuscitation☆,☆☆

Abstract

Aim

Methods

Results

Conclusion

Introduction

Section snippets

Methods

Characteristics of study subjects

Full cohort

Discussion

Conclusions

Conflict of interest statement

Ann Emerg Med

Resuscitation

Resuscitation

Prehosp Emerg Care

Resuscitation

Lancet

Lancet

Resuscitation

Ann Emerg Med

Heart disease and stroke statistics – 2014 update: a report from the American Heart Association

Circulation

Regional variation in out-of-hospital cardiac arrest incidence and outcome

JAMA

Clinical paper
Comparing the prognosis of those with initial shockable and non-shockable rhythms with increasing durations of CPR: Informing minimum durations of resuscitation☆,☆☆