Abstract 194: Effects of PEG-20k on Coronary Perfusion Pressure and Post-Resuscitation Myocardial and Cerebral Function in a Rat Model of Cardiac Arrest

Introduction: Epinephrine is the primary drug given during cardiopulmonary resuscitation (CPR), when given early, to reverse cardiac arrest (CA) by stimulation of α-adrenergic receptors in vascular smooth muscle. This increases coronary perfusion pressure (CPP) and increases rate of return of spontaneous circulation (ROSC). However, the use of epinephrine is not associated with a significant difference in long-term survival or favorable neurologic outcome when given late after arrest onset. In the present study, we compared the effects of aortic injection of polyethylene glycol-20k (PEG-20k) vs. epinephrine during CPR on CPP and postresuscitation myocardial and cerebral function in a rat model of CA. Hypothesis: Aortic injection of PEG-20k during CPR will increase CPP to the same extent as epinephrine without adversely affecting post-resuscitation myocardial and cerebral function. Methods: Twenty four male Sprague-Dawley rats weighing between 450-550 g were randomized into four groups: 1) PEG-20k 2) epinephrine 3) saline placebo 4) saline-intra-aorta (IA). Eight minutes of CPR was initiated after 6 minutes of untreated ventricular fibrillation. PEG-20k IA (10% est. total blood volume [1.8ml]), saline IA, saline IV or epinephrine IV (20ug/kg) was given after 4 minutes of CPR by continuous infusion over 3 minutes. CPP was recorded continuously and resuscitation was attempted with 4 Joule defibrillation. Myocardial function was measured at baseline, 2, 4, and 6 hours after ROSC by echocardiography and neurologic deficit scores (NDS) were recorded at 24, 48, and 72 hours after ROSC. Results: In both saline groups, CPP did not change. However, aortic injection of PEG-20k increased CPP significantly to the same extent as epinephrine (Fig 1). Post-resuscitation ejection fraction was significantly greater in PEG-20k compared to epinephrine (64 + 1 vs 45 + 3, p<0.05) and NDS was significantly improved in PEG-20k compared to epinephrine (100 + 50 vs 450 + 50, p<0.05).