异丙酚对健康志愿者局部脑血流的影响

目的 评价异丙酚对健康志愿者局部脑血流的影响,初步筛选其全麻作用的中枢靶位.方法 健康志愿者7名,性别不限,年龄24～34岁,体重50～69 kg,ASA Ⅰ级.志愿者随机静脉输注生理盐水4 mg·kg-1·h-1(清醒状态)、异丙酚妓应室靶浓度1.5 μg/ml(镇静状态)和3.0 μg/ml(意识消失状态),间隔至少48 h.静脉输注生理盐水10 min或达设定的效应室靶浓度后,稳定10 min,静脉注射99Tcm-双半胱乙酯0.5 mCi/kg,10 min后停止输注异丙酚使志愿者清醒,并在清醒后10 min内采用单光子发射断层扫描仪测定局部脑血流量(rCBF).结果 与清醒状态时比较,志愿者镇静状态时全脑CBF降低,大脑皮层rCBF降低(P<0.05),皮层下区rCBF差异无统计学差异(P>0.05),意识消失状态时全脑CBF、大脑皮层和皮层下区rCBF均降低(P<0.05);与镇静状态时比较,志愿者意识消失状态时小脑、顶叶、丘脑、扣带回、海马和额叶rCBF降低(P<0.05).3种状态下全脑CBF与BIS呈正相关(r=0.883,P<0.05).结论 异丙酚产生镇静效应时,健康志愿者大脑皮层rCBF降低,产生意识消失效应时大脑皮层区和皮层下区rCBF均降低,尤其是丘脑、海马、扣带回等区域,提示这些区域可能是异丙酚麻醉的中枢作用靶位.

Effect of propofol on regional cerebral blood flow in healthy volunteers

Objective To investigate the effect of propefol on regional cerebral blood flow (rCBF) in healthy volunteers. Methods Seven healthy volunteers aged 24-34 yr weighing 50-69 kg were enrolled in this study. The volunteers were kept in 3 sensorium states in a random order-- waking, sedated and unconscious states by administering normal saline iv at 4 ml·kg-1·h-1(awake), propofol by TCI at a target-effect site concentration of 1.5 μg/ml (sedated) and 3.0 μg/ml (unconscious) respectively. The interval between the two sensorium states was at least 48 h.99Tcm-ECD 0.5 mCi/kg was given iv after normal saline had been infused for 10 min or target effect-site concentration had been set for 10 min. TCI of propefol was stopped at 10 min after 99Tcm-ECD injection and rCBF was determined by using single photon emission computer tomography within 10 min.Results Compaired with the waking state, rCBF decreased throughout the brain, mainly in thalamus, cerebral cortex, hippocampus, cerebellum in sedated and uncouscious state. Conclusion Propofol induces a decrease in global CBF. Low doses of propefol affect preferentially the CBF in cortical areas while high doses of propofol .affect not only CBF in cortex but also subcortical brain structures, particularly thalamus, hippocampus and cingulated gyms, which may be the primary targets for anesthetic action.