The need to resume chest compressions immediately after defibrillation attempts: an analysis of post-shock rhythms and duration of pulselessness following out-of-hospital cardiac arrest.

AIM: Current consensus guidelines for cardiopulmonary resuscitation (CPR) recommend that chest compressions resume immediately after defibrillation attempts and that rhythm and pulse checks be deferred until completion of 5 compression:ventilation cycles or minimally for 2min. However, data specifically confirming the post-shock duration of asystole or pulseless electrical activity before return of spontaneous circulation (ROSC) are lacking. Our aim was to describe the frequency of the various post-shock cardiac rhythms and the duration of post-shock pulselessness in out-of-hospital non-traumatic cardiac arrest.

METHOD: Using prospectively-collected data from the Resuscitation Outcomes Consortium (ROC) Epistry database, the investigators reviewed monitor-defibrillator recordings of 176 patients who received defibrillation attempts in the out-of-hospital setting for ventricular fibrillation (VF) or ventricular tachycardia (VT) with absent pulses,.

RESULTS: Among 376 different defibrillation attempts delivered in the 176 patients, there were 182 resulting episodes of post-shock asystole. The mean interval of asystole after defibrillation was 69±136s (median 20s; IQR 36) and the mean interval for return of an organized rhythm was 64±157s (median 7s; IQR 26). The mean time to ROSC was 280±320s (median 136s; IQR 445).

CONCLUSION: After defibrillation attempts, the majority of patients remain pulseless for over 2min and the duration of asystole before return of pulses is longer than 120s beyond the shock gap in as many as 25%. These data support the recommendation to immediately resume chest compressions for 2min following attempted defibrillation.