The evaluation of cerebral function by diffusion weighted imaging after mild hypothermia therapy in a procine model of cardiac arrest / 中华急诊医学杂志

ABSTRACT

Objective To evaluate the effects of mild hypothermia therapy on cerebral function and edema as assessed by magnetic resonance imaging (MRI ) during the first 72 hours after restoration of spontaneous circulation (ROSC)in a porcine model.Methods Ventricular fibrillation was induced in 33 Inbred Wuzhishan miniature swine.After ventricular fibrillation untreated for 8 min,standard CPR was initiated and 30 animals got ROSC.The ROSC animals were randomly (random number)assigned to normothermia group (n=15 ) and hypothermia group (n =15 ).The hypothermia group immediately received endovascular cooling to regulate temperature to 33 ℃,which was maintained for 12 h,followed by passive rewarming at 0.5 ℃/h to 37 ℃.The two groups were scanned to get Diffusion-weighted imaging (DWI)at baseline (before experiment),6 h,12 h,24 h,and 72 h after ROSC.The statistical analysis was carried out with Student t test,One-way repeated-measures and Kaplan-Meier survival analysis.Results Compared with the normothermia group,the hypothermia group exhibited a higher 72-h survival rate (73.3% vs.40%,P<0.05),lower neurological deficit scores (43.81 vs.119.50;P<0.01),a lesser decrease in the apparent diffusion coefficient during DWI and milder cerebral edema on DWI image. Conclusions Cerebral edema occurred at early stage after ROSC.Cerebral edema was worst at 6 hours after ROSC and then subsided gradually.Hypothermia therapy could reduce cerebral edema and produce a protective effect on neurological function.MRI could effectively reflect the underlying trend of cerebral injury of swine within the first 72 h after ROSC,and demonstrated that hypothermia could reduce brain edema, increase cerebral blood flow,and reduce the production of toxic metabolites.DWI could monitor brain injury after resuscitation and could be used to evaluate the efficacy of hypothermia intervention dynamically.