A randomized comparison of cardiocerebral and cardiopulmonary resuscitation using a swine model of prolonged ventricular fibrillation☆

Abstract 

Background

Cardiocerebral resuscitation (CCR) is reportedly superior to cardiopulmonary resuscitation (CPR) for primary cardiac arrest in the prehospital setting. This study was done using a swine model of prolonged ventricular fibrillation (VF) to quantify the effect of the emergency medical services component of CCR with intraosseous access (CCR-IO) compared with standard CPR with intravenous access (CPR-IV) as it is typically performed during out-of-hospital cardiac arrest (OHCA) resuscitation in a prospective randomized fashion.

Methods

Fifty-three animals were instrumented under anesthesia and VF was electrically induced. After 10min of untreated VF, baseline characteristics were recorded, and animals were block randomized to one of two resuscitation schemes. The controls had mechanical chest compressions at 100/min with ventilations at a ratio of 30:2. Consistent with clinical practice, two 30-s pauses in chest compressions occurred to simulate attempts to accomplish endotracheal intubation at minutes 1 and 3 of CPR and successful IV access was simulated to occur three additional minutes after endotracheal intubation. The CCR group had continuous uninterrupted mechanical chest compressions at 100/min. No active ventilations were provided. A tibial IO needle was placed in real time for vascular access. Both groups received epinephrine (0.1mg/kg) as soon as access became available followed by 2.5min of chest compressions before the first 120J rescue shock attempt. After successful rescue shock, standardized post-resuscitative care was provided to a 20-min endpoint. Failed rescue shock was followed by continued chest compressions with positive pressure ventilation in both groups, repeat doses of epinephrine (0.01mg/kg) every 3min, and rescue shock every minute as long as a shockable rhythm persisted. Group comparisons were assessed using descriptive statistics. Proportions with 95% confidence intervals were calculated for VF termination, ROSC, and survival.

Results

Baseline characteristics and chemistries between the two groups at VF induction and after 10min of non-treatment were mathematically the same. The proportions of VF termination (0.50 vs. 0.82), ROSC (0.30 vs. 0.59), and 20-min survival (0.19 vs. 0.40) all strongly favored the CCR-IO group.

Conclusion

In this swine model of witnessed VF arrest with no bystander-initiated resuscitation, CCR-IO resulted in substantial improvement in all three outcomes relative to typical emergency medical services provided CPR-IV.

Keywords: Ventricular fibrillation, Heart arrest, Defibrillation, Cardiopulmonary resuscitation, Cardiocerebral resuscitation, Intraosseous