预先行上胸段硬膜外阻滞持续不同时间对兔脑血管痉挛的影响

Effects of preventive high thoracic epidural block for different periods on cerebral vasospasm in rabbits

目的:探讨预先上胸段硬膜外阻滞(HTEB)持续不同时间对蛛网膜下隙出血(SAH)后脑血管痉挛(CVS)的影响。方法:切开置管法制备HTEB模型的新西兰兔60只,随机分为6组(n=10):正常1d组(N1组)、正常7d组(N7组)、SAH 1d组(S1组)、SAH7d组(S7组)、HTEB+SAH 1d组(HS1组)、HTEB+SAH 7d组(HS7组)。硬膜外持续泵注1g/L罗哌卡因1ml/h至实验毕。用枕大池穿刺一次注血法(0.5ml/kg)制成兔SAH模型。用经颅多普勒(TCD)检测兔基底动脉(BA)平均血流速度(Vm),H-E染色后光镜观察BA痉挛及病变情况。结果:Vm:与N1组比较,S1组(P<0.01)和HS1组(P<0.05)均增快;与N7组比较,S7组增快(P<0.05),HS7组差异无统计学意义(P>0.05);S1组快于S7组(P<0.05),HS1组快于HS7组(P<0.05)。BA光镜观察:N1、N7组未见异常,S1、S7组管壁收缩、管腔狭窄,HS1、HS7组变化程度均轻于S1、S7组,HS7组狭窄程度轻于HS1。结论:预先HTEB可减轻兔实验性SAH后CVS的程度,持续时间越长疗效越好。

Objective：To investigate the effects of preventive high thoracic epidural block （PHTEB） for different periods on cerebral vasospasm （CVS） following subarachnoid hemorrhage （SAH） in rabbits. Methods.. T6-7 epidural space was opened and an epidura[ pipe was introduced to establish PHTEB model. Ropivacaine（1 g · L-1 ） was injected continuously through the pipe at 1 ml/h to block T1-5 sympathetic nerves. Sixty HTEB rabbits were assigned to 6 groups （n= 10 each）., the normal 1 day group （N1）, the normal 7 day group（N7） , SAH 1 day group （S1）, SAH 7 day group （$7） , PHTEB plus SAH 1 day group （HS1）, and PHTEB plus SAH 7 day group （HST）. CVS was developed by injecting non-anticoagulant autologous arterial blood （0.5 ml/kg） into the cisterna magna. Transcranial Doppler （TCD） ultrasonography was used to determine Vm of the basilar artery. The lesion and spasm of the basilar artery were observed under optical microscope. Results.. Compared with group N1, Vm was significantly increased in group S1 （P〈0.01） and increased in group HS1 （P〈0.05）. Compared with group NT, Vm was significantly increased in group S7 （P〈0.05） and similar to that in group HS7 （P〉0.05）. Vm in group S1 was significantly increased compared with group S7 （P〈0.05）; and that in group HS1 was significantly increased compared with group HS7 （P〈0.05）. Pathological observation showed no obvious changes in group N1 and N7. The vessel wall was shrunk and the lumina became narrow in group S1 and S7. The pathologic changes in group HS1 and HS7 were slighter than those in group S1 and ST;and Group HS7 was slighter than group HS1. Conclusion： PHTEB can relieve CVS in SAH rabbits, and the relieving effect increases with time of PHTEB.