Elsevier

Resuscitation

Volume 81, Issue 2, February 2010, Pages 155-162
Resuscitation

Clinical paper
Survival Increases with CPR by Emergency Medical Services before defibrillation of out-of-hospital ventricular fibrillation or ventricular tachycardia: Observations from the Resuscitation Outcomes Consortium

https://doi.org/10.1016/j.resuscitation.2009.10.026Get rights and content

Abstract

Background

Immediate defibrillation is the traditional approach to resuscitation of cardiac arrest due to ventricular fibrillation or tachycardia (VF/VT). Delaying defibrillation to provide chest compressions may improve survival. We examined the effect of the duration of Emergency Medical Services (EMS) cardiopulmonary resuscitation (CPR) prior to first defibrillation on survival in patients with out-of-hospital VF/VT.

Materials and methods

From a prospective multi-center observational registry of EMS-treated out-of-hospital cardiac arrest, we identified 1638 EMS-treated cardiac arrests with first recorded rhythm VF/VT or “shockable” and complete data for analysis. Survival to hospital discharge was determined as a function of EMS CPR duration prior to first shock.

Results

Compared to the reference group of first EMS CPR duration ≤45 s, the odds of survival was greater among patients who received between 46 and 195 s of EMS CPR before first shock (46–75 s odds ratio [OR] 1.15, 95% confidence interval [CI] 0.71–1.87; 76–105 s, OR 1.37, 95% CI 0.80–2.35; 106–135 s, OR 1.53, 95% CI 0.96–2.45; 136–165 s, OR 1.24, 95% CI 0.71–2.15; 166–195 s, OR 1.47, 95% CI 0.85–2.52). The benefit of EMS CPR before defibrillation was reduced when the duration of CPR exceeded 195 s (196–225 s, OR 0.95, 95% CI 0.47–1.81; 226–255 s, OR 0.91, 95% CI 0.46–1.79; 256–285 s, OR 0.46, 95% CI 0.17–1.29; 286–315 s, OR 1.29, 95% CI 0.59–2.85). An optimal EMS CPR duration was not identified and no duration achieved statistical significance.

Conclusion

In this observational analysis of VF/VT arrest, between 46 and 195 s of EMS CPR prior to defibrillation was weakly associated with improved survival compared to ≤45 s. Randomized trials are needed to confirm the optimal duration of EMS CPR prior to defibrillation and to assess the impact of first CPR duration on all initial rhythms.

Introduction

Treatment of out-of-hospital cardiac arrest (OHCA) due to ventricular tachycardia or ventricular fibrillation (VF/VT) has traditionally included defibrillation at the earliest opportunity.1, 2, 3 Use of automatic external defibrillators by first-responders has reduced the time to defibrillation, but the anticipated improvement in survival has not been observed.4, 5, 6 Delaying defibrillation to provide a period of cardiopulmonary resuscitation (CPR) may improve survival compared to immediate defibrillation by limiting end-organ ischemia, metabolically preparing the heart for defibrillation, and reducing reperfusion injury.7, 8, 9, 10 Previous studies have provided conflicting results concerning the potential benefit of EMS CPR before defibrillation for OHCA.5, 11, 12, 13 Within Resuscitation Outcomes Consortium (ROC) Epistry–Cardiac Arrest, we evaluated the effect of the duration of EMS CPR prior to the first defibrillation on survival in patients with out-of-hospital VF/VT.

Section snippets

Design and setting

The ROC Epistry–Cardiac Arrest is a prospective multi-center observational registry of OHCA in EMS agencies and receiving institutions in eight U.S. sites and three Canadian sites participating in the ROC clinical research network. Details of the ROC Epistry–Cardiac Arrest data management and quality assurance mechanisms have been described previously.14, 15

Patient population

The study cohort was drawn from all OHCA cases occurring within the catchment area of a participating EMS agency from December 1, 2005 to

Results

There were 13,601 cases of EMS-treated non-traumatic OHCA during the study period. An initial rhythm of VF/VT/shockable was reported in 3292 (24%). Of patients with VF/VT/shockable, we excluded 1304 (40%) with missing duration of EMS CPR or vital status at discharge, 26 (0.7%) with missing covariates for adjustment in the regression model, 143 (4%) EMS witnessed arrests, and 184 (6%) with a first EMS CPR duration of >315 s (Fig. 1). This resulted in 1638 cases of OHCA with an initial rhythm of

Discussion

Within this prospective multi-center observational cohort of VF/VT out-of-hospital cardiac arrest, between 46 and 195 s of EMS CPR before defibrillation was weakly associated with improved survival compared to ≤45 s of EMS CPR. The association between increased survival and 46–195 s of EMS CPR was more pronounced among patients with a longer time to first EMS unit arrival and witnessed OHCA. Among patients with unwitnessed OHCA or a short time to EMS unit arrival, there was no clear evidence of

Conclusion

In this observational study of OHCA due to VF/VT, delaying defibrillation to provide up to 195 s of EMS CPR was weakly associated with improved survival of VF/VT arrest. The strength of this association was more robust among patients with time to first EMS unit arrival of >5 min. Randomized trials are needed to evaluate this association and to assess the impact of EMS CPR before defibrillation in rhythms other than VF/VT.

Conflict of interest statement

The authors have no commercial affiliation or consultancy that could be construed as a conflict of interest with respect to the submitted data. In the interest of full disclosure, Tom Aufderheide reported that he is a member of the American Heart Association BLS Subcommittee; has received research grants from the National Institutes of Health (NIH); and has served as a consultant for Take Heart America, JoLife, and Medtronic. Graham Nichol reported that he is a member of the American Heart

Sources of funding

The ROC is supported by a series of cooperative agreements to 10 regional clinical centers and one Data Coordinating Center (5U01 HL077863, HL077881, HL077871, HL077872, HL077866, HL077908, HL077867, HL077885, HL077887, HL077873, HL077865) from the National Heart, Lung and Blood Institute in partnership with the National Institute of Neurological Disorders and Stroke, U.S. Army Medical Research & Material Command, The Canadian Institutes of Health Research (CIHR)-Institute of Circulatory and

Disclosures

Tom Aufderheide reported that he is a member of the American Heart Association BLS Subcommittee; has received research grants from the National Institutes of Health (NIH); and has served as a consultant for Take Heart America, JoLife, and Medtronic. Graham Nichol reported that he is a member of the American Heart Association ACLS Subcommittee and the Medic One Foundation Board of Directors; has received research grants from the NIH; has received equipment donations to support overseas medical

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