脑部亚低温对复苏后脑的保护作用

Protective effect of mild hypothermia on brain after resuscitation

目的：观察犬电击致室颤心脏停跳（ＶＦＣＡ）８分钟复苏后脑亚低温（３３℃）对脑脊液（ＣＳＦ）、脑组织中超氧化物歧化酶（ＳＯＤ）活力、丙二醛（ＭＤＡ）含量和脑皮质神经元超微结构的影响。方法：对犬行ＶＦＣＡ８分钟，开胸心肺复苏后观察４小时。１０只犬分为２组：正常脑温心肺复苏组（ＮＴ组，ｎ＝４）维持硬脑膜外温度３６～３７℃；选择性脑亚低温心肺复苏组（ＳＢＣ组，ｎ＝６）采用右侧颈总动脉灌注自体血冷却辅以头部表面降温维持硬脑膜外温度３３℃左右。结果：ＮＴ组复跳后各时点ＣＳＦ中ＳＯＤ活性较ＣＡ前均明显降低（Ｐ均＜０．０５），ＭＤＡ含量则均明显升高（Ｐ均＜０．０５），神经元核膜、线粒体、内质网等结构严重受损；ＳＢＣ组与ＮＴ组相比则复跳后各时点ＣＳＦ和脑组织中ＳＯＤ活性均明显升高（Ｐ均＜０．０５），ＭＤＡ含量均明显降低（Ｐ均＜０．０５），神经元超微结构损害明显减轻。结论：脑亚低温（３３℃左右）可能通过抑制脑内脂质过氧化反应和内源性氧自由基清除剂的消耗，对脑复苏起到有利的保护作用。

Objective:To study the protective effect of mild selective brain hypothermia (SBH,33 ℃) on super oxide dismutase (SOD) and malondialdehyde (MDA) contents in both cerebrospinal fluid (CSF) and brain tissue in dogs subjected to 8 minutes of ventricular fibrillationcardiac arrest,and the effect of SBH on damage of cerebral cortical neuron examined by electron microscope.Methods:Ten dogs were divided into 2 groups.In normothermic cardiopulmonary resuscitation (CPR) group (NT group, n =4),epidural temperature was maintained 36￣37 ℃.However,in SBH CPR group (SBC, n =6),epidural temperature was kept around 33 ℃ immediately after return of spontaneous circulation with cooling blood via right common carotid artery,together with head surface cooling.Results:SOD contents in CSF decreased obviously (all P <0 05) and MDA increased obviously (all P <0 05) at different time points after CPR compared with those before cardiac arrest in NT group.SOD contents in both CSF and brain tissue increased (all P <0 05) and MDA decreased significantly (all P <0 05) in SBC group as compared to those in NT group,and damage of cerebral neuron examined by electron microscope was obviously alleviated in SBC group.Conclusions:Mild SBH may reduce brain damage after cardiac arrest and benefit cerebral resuscitation,which may be associated with inhibitory effects on both lipid peroxidation and consumption of oxygen free radical scavengers during brain reperfusion.