The impact of increased chest compression fraction on survival for out-of-hospital cardiac arrest patients with a non-shockable initial rhythm

Objective: We evaluated the effect of chest compression fraction (CCF) on survival to hospital discharge and return of spontaneous circulation (ROSC) in out-of-hospital cardiac arrest (OHCA) patients with non-shockable rhythms. Methods: This is a retrospective analysis (completed in 2016) of a prospective cohort study which included OHCA patients from ten U.S. and Canadian sites (Resuscitation Outcomes Consortium Epistry and PRIMED study (2007–2011)). We included all OHCA victims of presumed cardiac aetiology, not witnessed by emergency medical services (EMS), without automated external defibrillator shock prior to EMS arrival, receiving > 1 min of CPR with CPR process measures available, and initial non-shockable rhythm. We measured CCF using the first 5 min of electronic CPR records. Results: Demographics of 12,928 adult patients were: mean age 68; male 59.9%; public location 8.5%; bystander witnessed 35.2%; bystander CPR 39.3%; median interval from 911 to defibrillator turned on 10 min:04 s; initial rhythm asystole 64.8%, PEA 26.0%, other non-shockable 9.2%; compression rate 80−120/min (69.1%); median CCF 74%; ROSC 25.6%; survival to hospital discharge 2.4%. Adjusted odds ratio (OR); 95% confidence intervals (95%CI) of survival for each CCF category were: 0−40% (2.00; 1.16, 3.32); 41−60% (0.83; 0.54, 1.24); 61−80% (1.02; 0.77, 1.35); and 81−100% (reference group). Adjusted (OR; 95%CI) of ROSC for each CCF category were: 0−40% (1.02; 0.79, 1.30); 41−60% (0.83; 0.72, 0.95); 61−80% (0.85; 0.77, 0.94); and 81−100% (reference group). Conclusions: We observed an incremental benefit from higher CCF on the incidence of ROSC, but not survival, among non-shockable OHCA patients with CCF higher than 40%.