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目的:采用功能磁共振波谱成像(MRS)及灌注成像(PWI)观察家兔失血性休克早期脑部能量代谢及脑部血流的变化。方法:对9只新西兰家兔行右侧股动脉置管,10 min内释放40%血容量制造失血性休克模型(维持平均动脉压40 mm Hg),分别于休克前(T0)及休克30 min(T1)、90 min(T2)、150 min(T3)监测心率、平均动脉压等,并行动脉血气分析。使用Achieva 3.0 T磁共振扫描仪分别行磁共振氢质子波谱(1H MRS)及磁共振磷谱(31P MRS),测定乙酰天门冬氨酸/肌酸(NAA/Cr)、乳酸/肌酸(Lac/Cr)及磷酸肌酸/无机磷酸(Pcr/Pi)、磷酸一酯(PME);同时行PWI,测定局部脑血流量(r CBF)、局部脑血容量(r CBV)及血流平均通过时间(MTT)。结果:随着时间从T0~T3,家兔代谢性酸中毒加深,脑部Pcr/Pi降低(P<0.05),PME升高(P<0.05),NAA/Cr及Lac/Cr则无明显变化(P>0.05);r CBF、r CBV及MTT均明显增加(P<0.05)。结论:失血性休克早期家兔已出现脑组织代谢紊乱,表现为无氧代谢增加,此时脑血流量增加,但血流速度减慢。
OBJECTIVE: To observe the changes of early brain energy metabolism and cerebral blood flow in hemorrhagic shock in rabbits by using functional magnetic resonance spectroscopy (MRS) and perfusion imaging (PWI). Methods: Nine New Zealand rabbits were catheterized on the right femoral artery, and a hemorrhagic shock model (mean arterial pressure 40 mm Hg) was established by releasing 40% of blood volume within 10 minutes. The rats were sacrificed at T0 and shock for 30 min (T1), 90 min (T2), 150 min (T3) monitoring of heart rate, mean arterial pressure, arterial blood gas analysis. The magnetic resonance spectroscopy (1H MRS) and magnetic resonance spectroscopy (31P MRS) were used to measure the changes of acetylcholastine / creatine (NAA / Cr) and lactate / creatine / Cr) and creatine phosphate / phosphate (Phosphomonoesterol) and monophosphate (PME). The PWI was measured simultaneously with r CBF, r CBV and blood flow through Time (MTT). Results: The metabolic acidosis in rabbits deepened with the increase of time from T0 to T3, the brain Pcr / Pi decreased (P <0.05), the PME increased (P <0.05), NAA / Cr and Lac / Cr had no significant changes (P> 0.05); r CBF, r CBV and MTT increased significantly (P <0.05). Conclusion: In the early stage of hemorrhagic shock, the metabolic disturbance of brain tissue has appeared in the brain, showing an increase of anaerobic metabolism. At this time, the cerebral blood flow increases but the blood flow velocity slows down.