Abstract P176: Resumption of Cardiopulmonary Resuscitation after Defibrillation Induces Recurrence of Ventricular Fibrillation
Introduction- Resuscitation guidelines 2005 advise to resume cardiopulmonary resuscitation (CPR) immediately after defibrillation. We hypothesized that this promotes recurrence of ventricular fibrillation (VF).
Methods- This was a prospective per-patient randomized controlled trial. We randomized Automated External Defibrillators (AEDs) used by first responders to either a) perform post-shock analysis and prompt rescuers to a pulse check - guidelines 2000 - or b) to resume CPR immediately after defibrillation - guidelines 2005. Between June 2006 and April 2008, we collected continuous ECG and impedance signal of all patients with a non-traumatic out-of-hospital cardiac arrest to whom a study AED was applied. We annotated and calculated time intervals between the first effective shock, moment of CPR resumption, moment of refibrillation, and subsequent defibrillation shock. Intervals are expressed as median and inter quartile range.
Results- We collected 120 ECGs of patients with a shockable rhythm: 61 were randomized to guidelines 2000 and 59 patients to guidelines 2005. In respectively 54% (33/61) and 56% (33/59) of the patients VF recurred after the first effective shock. Rescuers resumed CPR after 32 (24–45) and 8 (7–9) seconds (P<0.01), VF recurred at 35 (21–57) and 13 (8–25) seconds after the first effective shock (figure 1⇓; P=0.02), the time interval between resumption of CPR and refibrillation was 4 (−8–20) and 6 (1–22) seconds (P=0.59), and VF sustained for 98 (63–204) and 150 (98–261) seconds (P=0.15).
Conclusion- CPR induces recurrent VF. Immediate resumption of CPR after effective defibrillation is associated with early and longer lasting recurrence of VF.