Abstract 16917: Hemodynamic Effects of Synchronized Chest Compression in a Porcine Post Countershock PEA Model
Purpose: Post countershock Pulseless Electrical Activity (PCC-PEA) is encountered frequently during resuscitation from cardiac arrest. External chest compression (CC) remains the principal treatment for PCC-PEA, but unsynchronized CC may interfere with myocardial recovery. We investigated the efficacy of CC synchronized to PEA’s R waves as compared to standard CC in an animal model.
Methods: Seven domestic pigs weighing 35-42 kg were anesthetized, endotracheally intubated and mechanically ventilated. Aortic and right atrial pressures were invasively monitored and coronary perfusion pressure (CPP) calculated. Carotid blood flow (CBF) was continuously monitored by a flow probe. VF was electrically induced and left untreated for 3 minutes before delivering the 1st shock. If the post countershock rhythm remained in VF a 2nd shock was delivered after an additional period of VF from 1 to 2 minutes. Countershocks were continued until PEA was obtained. If shock resulted in a perfusing rhythm, VF was re-induced. After PEA was induced, 15 seconds of chest compression or medium energy pacing were delivered to the animal per another concurrent protocol. The rate of standard CC was 100. Animals were then randomized to receive synchronized or standard CC for 15 seconds, with continuous alternation of therapy for the maximum 120 seconds before the 1st administration of epinephrine. A standard CPR rescue protocol continued for maximum of 20 minutes. If ROSC was achieved, the animal received at least 4 minutes for recovery before the study sequence was repeated.
Results: A total of 32 matched synchronization pairs were obtained from 7 animals. The PEA pulse pressure was 2.47+2.34 mmHg and the PEA rate was 74+16.5. CC with R wave synchronization maintained CBF (53.6 vs. 46.7, p=0.11) and CPP (15.6 vs. 16.6 mmHg, p=0.34), and increased CBF stroke volume (=CBF/PEA rate) (0.76 vs. 0.47 ml, p=0.0004) as compared to standard CC.
Conclusions: During near complete electromechanical dissociation (true PEA), synchronization of external chest compression with R waves maintained CBF and CPP despite lower compression rates as compared to standard chest compression without synchronization. This may represent a first observation that synchronization may be beneficial even in true PEA.
Author Disclosures: W. Quan: Employment; Significant; ZOLL Medical. U. Herken: Employment; Significant; ZOLL Medical. N. Paradis: None.
- © 2015 by American Heart Association, Inc.