Abstract 14109: Basic Life Support With Reperfusion Injury Protection Improves 24 Hour Survival Outcomes in a Porcine Model of Prolonged Cardiac Arrest

Abstract

Introduction: Ischemic postconditioning (PC) using 3 intentional short pauses at the start of cardiopulmonary resuscitation (CPR) improves outcomes after cardiac arrest in pigs when epinephrine (epi) is used before defibrillation. Hypothesis: Basic life support (BLS) with PC will protect against reperfusion injury and enhance 24 hour functional recovery in the absence of epi. Methods: Female pigs (n=46; wt ~ 40 kg) were anesthetized (isoflurane). PC was delivered using 3 cycles alternating between automated CPR for 20 sec and no CPR for 20 sec at the start of each protocol. Protocol A: After 12 minutes of ventricular fibrillation (VF), 28 pigs were randomized in 4 groups: A/ Standard CPR (SCPR), B/ active compression-decompression with an impedance threshold device (ACD-ITD), C/ SCPR+PC (SCPR+PC) and D/ ACD-ITD+PC. Protocol B: After 15 min of VF, 18 pigs were randomized to ACD-ITD CPR or ACD-ITD + PC. The BLS duration was 2.75 min in Protocol A and 5 min in Protocol B. Following BLS up to 3 shocks were delivered. Without return of spontaneous circulation (ROSC) CPR was resumed and epi (0.5 mg) and defibrillation delivered. The primary end point was the incidence of major adverse outcomes at 24 h (defined as death or coma, refractory seizures and cardio-respiratory distress leading to euthanasia). Hemodynamic parameters and left ventricular ejection fraction (LVEF) were also measured. Data are presented as mean ± standard error of mean. Results: Protocol A: ACD-ITD CPR + PC (group D) provided the highest coronary perfusion pressure after 3 min of BLS compared with the 3 other groups (28 ± 6, 35 ± 7, 23 ± 5 and 47 ± 7 for groups A, B, C, D respectively, p= 0.05 by ANOVA). ROSC with BLS was achieved in 0, 3, 0, and 3 pigs in groups A, B, C and D, respectively (p=0.22) with no significant differences in 24-hour survival between groups. Protocol B: Four hours post ROSC, LVEF was significantly higher with ACD-ITD+IPC vs ACD-ITD alone (52.5 ± 3% vs. 37.5 ± 6.6%, p = 0.045). There was a significantly lower incidence of major adverse outcomes 24 hr after ROSC with ACD-ITD+PC compared with ACD-ITD alone (Log-rank comparison, p=0.027). Conclusion: BLS using ACD-ITD + PC mitigates post resuscitation cardiac dysfunction and facilitates neurological recovery after prolonged untreated VF in pigs.