亚低温治疗重型颅脑损伤模型的建立与评估

Establishment and evaluation of severe head injury model for treatment with mild hypothermia

目的建立更符合临床的亚低温治疗重型颅脑损伤的动物模型. 方法将120只SD大鼠随机分为降温前、降温6,12,24,48,72,96,120 h组,每组15只.采用自由落体致伤模型,用60 g×50 cm的致伤冲量致大鼠重型颅脑损伤,然后用医用降温床将体温降至32～34℃,制作亚低温治疗重型颅脑损伤动物模型.监测血压、心电图;每组抽血查血清K+、Na+、Mg2+水平;各时段大鼠取创伤处脑组织电镜观察神经元超微结构的改变. 结果随降温时间延长,大鼠死亡数目增加,血清K+、Mg2+ 呈进行性下降的趋势,血清Na+在各治疗时段波动不大.降温72 h组中有1只大鼠和降温96,120 h组中各有2只大鼠出现心律紊乱.电镜结果显示,在亚低温治疗中,脑水肿呈逐渐减轻的趋势.降温96, 120 h组各有1只大鼠在亚低温治疗中出现弥漫性肾小管坏死. 结论本实验所建立的动物模型符合临床上接受亚低温治疗的重型颅脑损伤患者生命体征、血电解质及脑组织微结构改变的特点.

Objective To set up an animal model with severe head injury that is similar to clinical condition and treated with mild hypothermia. Methods A total of 120 SD rats were randomly divided into eight groups (n=15 in each group), ie, before cooling, cooling 6, 12, 24, 48, 72, 96 and 120 hours groups. The model was induced by dropping a object of 60 g from a height of 50 cm onto the epidura and treated with mild hypothermia (32-34℃). Blood pressure and ECG were observed and serum K+, Na+ and Mg 2+levels measured. The change of neuron microstructure in rat cerebral traumatic tissue of every group was observed by transmission electron microscope (TEM). Results Animal mortality increased but serum K+ and Mg 2+levels gradually decreased with the treating time lasting. Serum Na+ showed insignificant change. Bradytachycardia occurred in one rat of 72 hours group, two of 96 hours group and two of 120 hours group. TEM showed that the rat’s encephaledema presented gradual relief trend during mild hypothermia treatment. There was one rat in 96 hours group and one in 120 hours group with diffuse tubuli renales necrosis. Conclusion The established model is in conformity with the characteristics of vital sign, serum electrolyte and cerebral microstructure of clinical severe head injury treated with mild hypothermia.