When reason is away, smiles will play.     --- Paul Eluard and Benjamin Péret

clinicaltrials.gov Identifier: NCT00120965.

BACKGROUND Peri-shock pauses are pauses in chest compressions prior to and following defibrillatory shock. We examined the relationship between peri-shock pauses and survival to hospital discharge. METHODS We included out-of-hospital cardiac arrest (OHCA) patients in the Resuscitation Outcomes Consortium Epistry-Cardiac Arrest who suffered arrest between December 2005 and June 2007, presented with a shockable rhythm (ventricular fibrillation or pulseless ventricular tachycardia) and had CPR process data for at least one shock (n=815). We used multivariable logistic regression to determine the association between survival and peri-shock pauses. RESULTS In an analysis adjusted for Utstein predictors of survival, the odds of survival were significantly lower for patients with pre-shock pause ≥20 seconds (OR: 0.47, 95%CI: 0.27, 0.82) and peri-shock pause ≥40 seconds (OR: 0.54, 95%CI: 0.31, 0.97) when compared to patients with pre-shock pause <10 seconds and peri-shock pause <20 seconds. Post-shock pause was not independently associated with a significant change in the odds of survival. Log linear modeling depicted a decrease in survival to hospital discharge of 18% and 14% for every 5 second increase in both pre- and peri-shock pause interval (up to 40 and 50 seconds respectively) with no significant association noted with changes in the post-shock pause interval. CONCLUSIONS In patients with cardiac arrest presenting in a shockable rhythm longer peri-shock and pre-shock pauses were independently associated with a decrease in survival to hospital discharge. The impact of pre-shock pause on survival suggests refinement of automatic defibrillator software and paramedic education to minimize pre-shock pause delays may have significant impact on survival.