New conventional long-term survival normovolemic cardiac arrest pig model

Aim of the study: A reproducible long-term intensive care and outcome cardiac arrest model for exploring new cerebral preservation strategies is needed. We tried to determine effects and limitations of current therapies after different 'no-flow' times.

Methods: Thirty-five female Large White Breed pigs (26-37kg) were included in the study. Three pigs served as sham animals without cardiac arrest (CA). Ventricular fibrillation (VF) CA was induced in 32 animals for 0, 7, 10 and 13min (each group consisting of 8 animals), followed by 8min of chest compressions, mechanical ventilation and vasopressors. Thereafter, up to 3 defibrillations were delivered. After restoration of spontaneous circulation (ROSC), the animals underwent intensive care for 20h. Neurologic examination was performed at designated time points using a neurologic deficit (ND) and an overall performance category (OPC) score.

Results: Restoration of spontaneous circulation was achieved in 8 of 8 animals in the 0min-group, 6 of 8 in the 7min-group, 7 of 8 in the 10min-group and 0 of 8 in the 13min-group. All animals of the sham-group and 0min-group were neurologically intact survivors; the 7 and 10min-groups showed a median ND of 55%(26;94) and 73%(58;78), respectively. There were no significant differences between the 7 and 10min-groups regarding OPC and NDS. Coronary perfusion pressure during CPR decreased concordantly with 'no-flow' times with a tendency towards significance.

Conclusion: This study established a reproducible cardiac arrest and resuscitation model in pigs which will be used to test novel resuscitation strategies to improve neurologic outcome after cardiac arrest.