Abstract 304: Conversion of Ventricular Fibrillation to an Organized Rhythm Without a Defibrillator

Abstract

Background: Reports of pulseless ventricular tachycardia (VT) or ventricular fibrillation (VF) converting to an organized rhythm without defibrillator use are rare. We wish to report a series of such cases in the randomized Circulation Improving Resuscitation Care (CIRC) trial comparing outcome between integrated AutoPulse CPR (iA-CPR) and Manual-CPR (M-CPR) in patients with out-of-hospital cardiac arrest (OHCA) of presumed cardiac etiology. Methods: Defibrillator ECGs were studied to determine rhythm one minute after defibrillation attempts and rhythm immediately before the next defibrillation attempt. Rhythms were categorized as VF, pulseless VT, asystole or an organized rhythm. Organized rhythms were classified as either pulseless electrical activity (PEA) or as return of spontaneous circulation (ROSC) if accompanied by a steep increase in EtCO2, trans-thoracic impedance showing typical “dips,” and a detectable pulse. Results: In 1603 patients with analyzable date and a shockable rhythm there were 13 cases of VF/VT (10/3) conversions to PEA or ROSC during periods with external chest compressions without defibrillation attempts. In eight of the 10 VF cases chest compressions converted VF to PEA (5 iA-CPR vs 3 M-CPR) and in two to ROSC (2 iA-CPR vs 0 M-CPR). With VT one case converted to PEA (M-CPR ) and two to ROSC (2 iA-CPR vs 0 M-CPR). Examples will be presented. Conclusion: This study documents that conversion of VF or VT to an organized rhythm during CPR without electrical assistance is possible but rare.