Abstract 2658: Emergency Preservation and Resuscitation (EPR) by Deep Cerebral Hypothermia Improves Neurological Outcome after Prolonged Normovolemic Cardiac Arrest in Swine
Background In former studies we have shown that induction of deep cerebral hypothermia via ice cold saline aortic flush already during cardiac arrest (CA) no-flow to mitigate reperfusion injury (e.g. EPR), followed by hypothermic stasis for 20 minutes and delayed resuscitation, improved neurologic outcome after prolonged normovolemic CA in swine, as compared to conventional resuscitation methods. We hypothesize that EPR combined with chest compressions will further improve outcome in the same model.
Methods Swine (27–37 kg) were put into ventricular fibrillation CA for 15 min, followed by 20 minutes of: I) conventional resuscitation by chest compressions and vasopressors (C, n=8); II) EPR induced via a cold saline aortic flush (4°C; 200 ml/kg) and hypothermic stasis without chest compreesions (EPR, n=8); and III) EPR induced as in II, combined with chest compressions and vasopressors (EPR+CC, n=8). At 35 min after CA, cardiopulmonary bypass was initiated, followed by defibrillation attempts. Controlled ventilation and mild hypothermia (34.5°C) were continued for 20 h, and swine were allowed to survive for 9 days with final neurological evaluation using neurological deficit score (NDS, 100%=brain dead, 0–10%=normal) and overall performance category (OPC; 1=normal; 2=slightly handicapped; 3=severely handicapped; 4=comatose; 5=dead or brain dead).
Results The aortic flush decreased brain temperature from 38.5°C to 16.7±2.5°C within 235±27 sec in the EPR group, and to 13.3±6.0°C within 323±68 sec in the EPR+CC group. In the C-group, restoration of spontaneous circulation (ROSC) was achieved in 4/8 swine, one survived to 9 days with OPC 3 and NDS 45%. In the EPR-group, ROSC was achieved in 7/8 swine, 5 survived to 9 days with a median OPC 3 (IQR 2–3), and median NDS 45% (IQR 36–50). In the EPR+CC group, ROSC was achieved in 8/8 swine, 7 survived to 9 days with a median OPC 2 (IQR 1–2), and median NDS 13% (IQR 5–21) (ROSC, p=0.08; OPC, p=0.02; NDS EPR vs. EPR+CC, p=0.003).
Conclusions EPR by deep cerebral hypothermia during cardiac arrest is feasible, and combined with chest compressions, improves neurological outcome after prolonged normovolemic CA in swine. Further experiments are necessary to optimize this novel concept of EPR, before considering clinical trials.