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

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.

Conflict of interest statement

Conflict of interest statement: See Appendix

Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Figures

Figure 1

Study cohort and exclusions. OOHCA indicates out-of-hospital cardiac arrest; EMS, emergency medical services; AED, automated external defibrillator; VF/VT, ventricular fibrillation or tachycardia; ROC, Resuscitation Outcomes Consortium; and CPR, cardiopulmonary resuscitation. *Only cases with initial rhythm of VF/VT among those not witnessed by EMS and for which no shock was delivered by an AED before EMS arrival.

Figure 2

Smoothing spline representing the unadjusted incremental probability of return of spontaneous circulation corresponding to a linear increase in chest compression fraction.

Figure 3

Return of spontaneous circulation for each category of chest compression fraction. ROSC indicates return of spontaneous circulation; CI, confidence interval; and CCF, chest compression fraction.