[The evaluation of cerebral function by diffusion weighted imaging after norepinephrine-induced hypertensive perfusion therapy in pig model of cardiac arrest].

OBJECTIVE: To evaluate the changes in cerebral function of pigs with cardiac arrest (CA) after recovery of spontaneous circulation (ROSC) after hypertension perfusion therapy induced by norepinephrine (NE). METHODS: Ventricular fibrillation (VF) was induced by electrical stimulation, and standard cardiopulmonary resuscitation (CPR) was performed after VF for 4 minutes. The pigs with successful ROSC were randomly divided into two group, each n=5. The pigs in the hypertensive reperfusion group were given with NE immediately to maintain the mean arterial pressure (MAP) at 130% before VF for 4 hours; MAP of the pigs in normal reperfusion group was maintained for 4 hours as baseline. The changes in hemodynamics were observed for 4 hours in both groups. Cerebral cortex was scanned with diffusion weighted imaging (DWI) before VF and 1 hour and 3 hours after ROSC, and the dynamic changes in brain functional imaging were observed. Twenty-four hours after ROSC, brain biopsy were collected and examined after hematoxylin and eosin staining (HE). RESULTS: Compared with the normal reperfusion group, heart rate (HR), MAP, cardiac output (CO) and coronary perfusion pressure (CPP) in the hypertensive reperfusion group showed a tendency to increase (ROSC 30 minutes HR: 167±8 bpm vs. 140±15 bpm, ROSC 1 hour MAP: 131±9 mm Hg vs. 108±10 mm Hg, ROSC 1 hour CO: 4.9±0.1 L/min vs. 3.4±0.5 L/min, ROSC 2 hours CPP: 118±12 mm Hg vs. 88±1 mm Hg, P<0.05 or P<0.01). There was no obvious abnormality as shown by DWI before and after resuscitation, and the apparent diffusion coefficient (ADC) showed a tendency to decrease after resuscitation in both groups. The ADC in the normal reperfusion group was decreased more than that in the hypertensive reperfusion. Pathological study showed that the protective effect of the hypertensive reperfusion on brain tissue was better than that of the normal reperfusion group. CONCLUSION: Hypertensive reperfusion can produce hemodynamic changes, and an increase in cerebral blood flow, thus it produces a protective effect on brain to promote the recovery of neurological function in pigs with CA after resuscitation.