Abstract 174: Coronary Perfusion Pressure During External Chest Compression in Pseudo-EMD, Comparison of Systolic and Diastolic Synchronization
Background: The fraction of cardiac arrest patients presenting with pulseless electrical activity is increasing, and it is likely that many of these patients have pseudo-electromechanical dissociation (P-EMD: no palpable pulse, but pulse pressure > 10 mm Hg). The efficacy of external chest compression synchronized with the residual cardiac systole or diastole of P-EMD has not been fully evaluated.
Hypothesis: During external chest compression in P-EMD, the coronary perfusion pressure (CPP) will be greater with systolic phase (S-Phase) synchronization compared with diastolic phase (D-Phase) synchronization.
Methods: A porcine model of hypoxia induced P-EMD with peak aortic pressures below 50 mm Hg was used. Chest compressions were performed by load distributing band devices. Cardiac S-Phase synchronization was initiated synchronous with the onset of isovolemic contraction, D-Phase synchronization was initiated after the end of the systolic intraventricular pressure waveform. Paired 10 second intervals of S-Phase and D-Phase synchronized compressions were performed randomly during stable P-EMD and coronary perfusion pressures (CPP) were compared.
Results: Stable P-EMD was achieved in 5 animals, with 3±1 pairs of S-Phase and D-Phase synchronization per animal. Mean (± SEM) CPP during S-Phase was 36 ± 2 mm Hg and 27 ± 2 during D-Phase (p < 0.001). In all cases, S-Phase CPP was higher than adjoining D-Phase CPP. Figure: Aortic (Ao) and right atrial (RA) pressures during S-Phase and D-Phase synchronization. Limitations: The effect of synchronization on outcomes was not evaluated. The relationship between CPP and actual blood flow during synchronization has not been validated.
Conclusions: During P-EMD, synchronization of external chest compression with residual cardiac systole was associated with higher CPP compared to synchronization with diastole, and may improve outcome from cardiac arrest.
- © 2010 by American Heart Association, Inc.