Abstract 138: Effects of Compression Rate on Coronary Perfusion Pressure and Carotid Blood Flow in a Porcine Model of Shock-Induced Pulseless Electrical Activity

Background: The 2010 AHA guidelines recommend a chest compression (CC) depth of at least 2 inches. However, most clinical studies found an inverse association between CC depth and rate. The effect of CC rate on coronary perfusion pressure (CPP) and carotid blood flow (CBF) has not been determined. This study was to investigate hemodynamic responses to CC at different compression rate in a post- shock PEA porcine model. Methods: Ventricular fibrillation was electrically induced and untreated for 2 - 7 mins in 12 domestic pigs weighing 22-24kg. Post- shock PEA was induced with electric shock. Peak aortic pressures below 40 mm Hg was used to identify a qualified PEA. Once PEA was induced, animals received 30 sec PEA-triggered synchronized sternal CC using a modified Thumper device. CC depth was maintained at 2 inches. If animals were resuscitated after the study sequence PEA induction and the study sequence were repeated after 30 mins recovery. Results: A total of 1102 compression cycles from 29 qualified PEA events were included in the analyses. The rate of induced PEA varied from 30 to 125 bpm. When the CC rate increased from 80 to 120 bpm with fixed CC depth, CPP increased by 5.6 mmHg (32.9%) and CBF increased by 46.4 ml/min (50.2%). Both CPP and CBF were positively correlated to CC rate with correlation coefficients of 0.32 and 0.49 (p=0), respectively. Linear regression found a positive trend for both CPP and CBF with slopes over the CC rate of 0.14 and 1.16 (p=0), respectively. Conclusions: In this shock induced PEA porcine model, both CPP and CBF increased with CC rate. These results indicate that faster sternal CC would generate better coronary and cerebral perfusion in the range between 80 to 120 bpm.