Abstract 137: Effect Of Chest Compression Release Velocity On Cerebral Perfusion Pressure In A Porcine Experimental Model Of Cardiac Arrest.

Abstract

Background: Previous studies have shown that chest compression release velocity (CCRV) of over 400mm/s is associated with improved survival and favorable neurologic outcome after cardiac arrest. However, it is uncertain whether CCRV during CPR is related to cerebral perfusion pressure (CePP). The purpose of this study was to evaluate the association between CCRV and CePP in a porcine cardiac arrest model. Methods: After 6 minutes of untreated ventricular fibrillation, 2 cycles of basic life support (BLS) and 12 cycles of advanced cardiovascular life support (ACLS) were conducted. During ACLS phase, CCRV was accelerated from 250mm/s to 450mm/s by 50mm/s (accelerating group) or decelerated from 450mm/s to 250mm/s by 50mm/s (decelerating group). Both groups performed BLS with the self-set value of the mechanical CPR device (LUCAS 2 chest compression system, CCRV of 170mm/s). Twenty-four pigs were randomly assigned to each group. Macrovascular circulation (CePP) and microvascular circulation using laser doppler flowmetry presented as a fraction of the baseline flow (f-LDF) were measured. We excluded the last 2 cycles of ACLS phase from the analysis due to time-dependent deterioration effects of hemodynamic outcomes. Linear mixed model was used to measure the median difference in CePP and f-LDF according to CCRV. Results: A total of 24 pigs were analyzed. Decelerating group of CCRV of 400mm/s showed significantly higher CePP values compared to the group of 170mm/s. Effect of changes in CCRV on CePP, stratified by groups, are as follows (median, [95% confidence intervals]): 1. Accelerating group: CCRV of 170mm/s; reference, 250mm/s; -1.98 [-10.78 - 11.79] mmHg, 300mm/s; -1.88 [-11.15 - 12.55] mmHg, 350mm/s; -2.55 [-11.46 - 12.24], 400mm/s; -6.05 [-5.59 - 16.86], and 2. Decelerating group: CCRV of 170mm/s; reference, 250mm/s; 5.71 [-16.27 - 27.11] mmHg, 300mm/s; 6.01 [-16.28 - 27.90] mmHg, 350mm/s; 6.96 [6.36 - 47.70], 400mm/s; 26.96 [6.36 - 47.70]. However, there was no significant CCRV effects on f-LDF (Accelerating CCRV of 400mm/s; 1.54 [ -0.03 - 3.10] and decelerating CCRV of 400mm/s; -2 [-4.42 - 0.34]). Conclusion: In a VF cardiac arrest porcine study, CCRV of 400mm/s at early phase of CPR has positive effects on CePP.