Elsevier

Resuscitation

Volume 82, Issue 12, December 2011, Pages 1501-1507
Resuscitation

Clinical paper
The impact of increased chest compression fraction on return of spontaneous circulation for out-of-hospital cardiac arrest patients not in ventricular fibrillation

https://doi.org/10.1016/j.resuscitation.2011.07.011Get rights and content

Abstract

Objective

Greater chest compression fraction (CCF, or proportion of CPR time spent providing compressions) is associated with better survival for out-of-hospital cardiac arrest (OOHCA) patients in ventricular fibrillation (VF). We evaluated the effect of CCF on return of spontaneous circulation (ROSC) in OOHCA patients with non-VF ECG rhythms in the Resuscitation Outcomes Consortium Epistry.

Methods

This prospective cohort study included OOHCA patients if: not witnessed by EMS, no automated external defibrillator (AED) shock prior to EMS arrival, received >1 min of CPR with CPR process measures available, and initial non-VF rhythm. We reviewed the first 5 min of electronic CPR records following defibrillator application, measuring the proportion of compressions/min during the resuscitation.

Results

Demographics of 2103 adult patients from 10 U.S. and Canadian centers were: mean age 67.8; male 61.2%; public location 10.6%; bystander witnessed 32.9%; bystander CPR 35.4%; median interval from 911 to defibrillator turned on 8 min:27 s; initial rhythm asystole 64.0%, PEA 28.0%, other non-shockable 8.0%; median compression rate 110/min; median CCF 71%; ROSC 24.2%; survival to hospital discharge 2.0%. The estimated linear effect on adjusted odds ratio with 95% confidence interval (OR; 95%CI) of ROSC for each 10% increase in CCF was (1.05; 0.99, 1.12). Adjusted (OR; 95%CI) of ROSC for each CCF category were: 0–40% (reference group); 41–60% (1.14; 0.72, 1.81); 61–80% (1.42; 0.92, 2.20); and 81–100% (1.48; 0.94, 2.32).

Conclusions

This is the first study to demonstrate that increased CCF among non-VF OOHCA patients is associated with a trend toward increased likelihood of ROSC.

Introduction

Survival to hospital discharge for out-of-hospital cardiac arrest (OOHCA) varies by community, but rarely exceeds 8%.1, 2 Bystander cardiopulmonary resuscitation (CPR) and defibrillation are two of only a few modifiable factors clearly associated with increased survival for OOHCA,3 and the importance of good quality CPR is increasingly being recognized.4, 5, 6, 7, 8 There is compelling evidence from animal studies suggesting that frequent and prolonged CPR interruptions have a detrimental effect on survival and neurological outcomes.9, 10, 11 Human studies also demonstrate that experienced CPR providers stop CPR frequently during out-of-hospital 12 and in-hospital resuscitation. 13 The 2005 emergency cardiovascular care guidelines that recommended changing the chest compression to ventilation ratio from 15:2 to 30:2 did thereby reduce interruptions to chest compressions.14 However, a growing number of reports suggest the benefit of chest compression-only CPR, avoiding interruptions for ventilation.15, 16, 17, 18, 19.

Compression fraction is defined as the proportion of CPR time spent providing chest compressions. A recent study by Christenson et al. evaluated the incremental benefit of higher chest compression fraction on survival to hospital discharge for OOHCA patients with an initial ECG rhythm of ventricular fibrillation or tachycardia (VF/VT).20 These authors described the relationship between increasing chest compression fraction and survival to hospital discharge, the highest survival (29%) being observed in the group of patients where 61–80% of CPR time was spent doing chest compressions. Survival is more common among patients with an observed initial rhythm of VF/VT compared with all other initial cardiac rhythms, but this VF/VT group generally represents less than 30% of all cardiac arrest patients.1, 2

The objective of the present study was to estimate the independent effect of chest compression fraction on return of spontaneous circulation (ROSC) in a cohort of OOHCA patients with an initial rhythm other than VF/VT.

Section snippets

Study design

This was an observational cohort study of OOHCA patients prospectively enrolled in the Resuscitation Outcomes Consortium (ROC) Cardiac Arrest Epistry. ROC is a clinical network of 11 regional centers distributed across North America conducting research in the fields of OOHCA and serious traumatic injury.21 The ROC cardiac arrest epidemiological registry or “Epistry” has been collecting population-based prospective data on OOHCA from more than 260 EMS agencies since December 2005.22 Information

Characteristics of study subjects

Among the 16,487 cardiac arrest cases of suspected cardiac etiology for which resuscitation was attempted, 14,795 were not witnessed by EMS and did not receive a shock before EMS arrival. Of these, 11,158 had an initial rhythm other than VF/VT and 2332 had CPR process measures, making them eligible for analysis. Outcome data were missing for 51 patients and 178 had been enrolled in an interventional study, leaving 2103 for the available data set (Fig. 1).

Overall patient and system

Discussion

This large multi-center prospective cohort study is the first to suggest that increased chest compression fraction results in a higher likelihood of ROSC in a population of OOHCA patients presenting with initial rhythms other than VF/VT—representing the majority of cardiac arrests in this setting. The observation is independent of other known potential predictors of ROSC.

The positive correlation, demonstrated by the smoothing spline representing the unadjusted incremental probability of ROSC (

Conflict of interest statement

  • -

    Siobhan Everson-Stewart, Jim Christenson, Douglas Andrusiek, Judy Powell, Tom P. Aufderheide, Robert Berg, and Ian G. Stiell have no conflict of interest to declare.

  • -

    Christian Vaillancourt, once received a small (<$25,000) unrestricted grant from Medtronic PhysioControl in 2001 to study to optimum placement of AEDs in the community.

  • -

    Sheldon Cheskes, once received a small honorarium from Zoll as a speaker.

  • -

    Graham Nichol, has the following conflicts of interests to disclose:

Research Grants:

Acknowledgements

The present multi-center observational cohort study was possible thanks to the same clinical research network (ROC) that collected data for the Christenson study on the effect of chest compression fraction in a cohort of VF/VT OOHCA patients.

We would like to acknowledge the professional care provided by first responders and paramedics, the hard labor of research team members at each participating sites, and the diligent supervision provided by the central data coordinating center study

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    A Spanish translated version of the summary of this article appears as Appendix in the final online version at doi:10.1016/j.resuscitation.2011.07.011.

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