Elsevier

Resuscitation

Volume 79, Issue 1, October 2008, Pages 61-66
Resuscitation

Clinical paper
The impact of prehospital transport interval on survival in out-of-hospital cardiac arrest: Implications for regionalization of post-resuscitation care,☆☆

https://doi.org/10.1016/j.resuscitation.2008.05.006Get rights and content

Summary

Objective

There is growing evidence that therapeutic hypothermia and other post-resuscitation care improves outcomes in out-of-hospital cardiac arrest (OHCA). Thus, transporting patients with return of spontaneous circulation (ROSC) to specialized facilities may increase survival rates. However, it is unknown whether prolonging transport to reach a designated facility would be detrimental.

Methods

Data from OHCA patients treated in EMS systems that cover approximately 70% of Arizona's population were evaluated (October 2004–December 2006). We analyzed the association between transport interval (depart scene to ED arrival) and survival to hospital discharge in adult, non-traumatic OHCA patients and in the subgroup who achieved ROSC and remained comatose.

Results

1846 OHCA occurred prior to EMS arrival. Complete transport interval data were available for 1177 (63.8%) patients (study group). 253 patients (21.5%) achieved ROSC and remained comatose making them theoretically eligible for transport to specialized care. Overall, 70 patients (5.9%) survived and 43 (17.0%) comatose ROSC patients survived. Mean transport interval for the study group was 6.9 min (95% CI: 6.7, 7.1). Logistic regression revealed factors that were independently associated with survival: witnessed arrest, bystander CPR, method of CPR, initial rhythm of ventricular fibrillation, and shorter EMS response time interval. There was no significant association between transport interval and outcome in either the overall study group (OR = 1.2; 0.77, 1.8) or in the comatose, ROSC subgroup (OR 0.94; 0.51, 1.8).

Conclusion

Survival was not significantly impacted by transport interval. This suggests that a modest increase in transport interval from bypassing the closest hospital en route to specialized care is safe and warrants further investigation.

Introduction

For many years it was thought that the only significant determinants of survival from out-of-hospital cardiac arrest (OHCA) occurred in the prehospital setting.1, 2 Even with the restoration of spontaneous circulation a sense of futility often prevents aggressive in-hospital post-resuscitation care in patients without an immediate return of cerebral activity.3, 4, 5, 6 Recent evidence, however, suggests that survival and neurological outcome can be dramatically improved by in-hospital post-resuscitation care despite persistent coma after arrest.7, 8, 9 Subsequently, consideration has been given to bypassing local hospitals en route to regional cardiac arrest centers staffed and equipped to provide specialized post-resuscitation care.10, 11 The question remains whether it is detrimental to prolong the transport of critically ill ROSC patients.

Numerous EMS leaders in Arizona have suggested developing regional “Cardiac Arrest Centers” and EMS protocols aimed at taking comatose ROSC patients to these centers for specialized post-resuscitation care. However, we have been able to find only one evaluation of the association between TI and outcome in OHCA within the peer-reviewed literature.10 This prompted us to analyze our statewide OHCA database with the intent of identifying evidence for the safety of increased time spent in transport.

Section snippets

Methods

The State of Arizona, through its Bureau of Emergency Medical Services and Trauma System, initiated a statewide, prospective observational cohort study of OHCA victims on whom resuscitation was attempted in the field. The Save Hearts in Arizona Registry & Education (SHARE) Program database contains information on OHCA patients from 48 EMS agencies/fire departments responsible for responding to prehospital medical emergencies for approximately 70% of the 5.5 million residents of the state.

A

Results

Figure 1 shows the cases that were entered into the database during the study period. 1846 were adults with OHCA of presumed cardiac etiology occurring prior to EMS arrival. Among these cases, 1177 (63.8%) had complete TI data and this cohort comprised the overall study group. Table 1 shows the demographics, event characteristics, initial cardiac rhythms, and patient outcomes. 280 patients achieved ROSC (23.8%). 253 patients (21.5%) achieved ROSC but remained comatose and would have been

Discussion

For decades, despite remarkable survival rates in a few settings,19, 20 the vast majority of systems have reported dismal survival rates for OHCA.21, 22, 23, 24, 25 Additionally, many experts have considered prehospital care to be the only significant determinant of survival. In 1988, Kellerman and associates identified that OHCA patients who failed to be successfully resuscitated in the field had essentially no chance of being resuscitated in the hospital. This led to the conclusion that,

Limitations

The conclusions and significance of our findings are impacted by several limitations. First, although the OHCA cases in the SHARE registry are prospectively collected, this query was not an a priori hypothesis. Thus, the potential for impact by confounding issues is significant as with any retrospective evaluation of a data set. This was not a controlled trial but, rather, an observational analysis. In addition, the fact that data for TI was missing in 38% of cases introduces the potential for

Conclusion

Using a statewide database, we evaluated the association between TI and outcome in OHCA patients and in the subgroup of patients with ROSC who remained comatose in the field. No causal association was identified in any cohort. While not proof, this supports the concept that a modest increase in TI for the purpose of transport to a regional cardiac center is safe. This analysis is relevant to future trials that evaluate the impact of regionalized post-resuscitation care as well as to EMS systems

Conflict of interest

None.

Acknowledgement

This study was funded in part by the Arizona Department of Health Services, Bureau of EMS and Trauma System.

References (41)

Cited by (83)

View all citing articles on Scopus

A Spanish translated version of the summary of this article appears as Appendix in the final online version at doi:10.1016/j.resuscitation.2008.05.006.

☆☆

Presented in part to the Annual Scientific Meeting of the National Association of EMS Physicians, 11 January 2008, Phoenix, AZ.

View full text