不同体位时健康志愿者脑血液动力学的变化

目的 探讨不同体位时健康志愿者脑血液动力学的变化.方法 60名右利手男性健康志愿者,年龄22～ 26岁,身高167～ 178 cm,体重51～67 kg,采用随机数字表法,将其随机分为4组(n=15):头低15°组(Ⅰ组)、头低30°组(Ⅱ组)、头高15°组(Ⅲ组)和头高30°组(Ⅳ组).采用经颅多普勒技术监测右侧大脑中动脉(MCA)和颈内动脉颅外段(EICA)血流信号,分别于平卧位(基础状态)、体位改变即刻(T1)、10 min(T2)和30 min(T3)时记录收缩期血流速度(Vs)、舒张期血流速度(Vd)、平均血流速度(Vm)、搏动指数(PI)和阻力指数(RI),并计算Lindegaard指数.结果 与基础值比较,Ⅱ组在T2时Lindegaard指数升高,在T2,3时MCA的Vs和Vm降低,Ⅳ组在T2时MCA的Vs降低,在T2,3时MCA的Vd和Vm降低,T2时EICA的PI降低(P＜0.05),其他2组各时点上述指标差异无统计学意义(P＞0.05).结论 健康成人在头低30°和头高30°时脑血流速度降低,而头低15°和头高15°时脑血流速度没有变化.

Changes in cerebral hemodynamics in different body positions in healthy volunteers

Objective To investigate the changes in cerebral hemodynamics in different body positions in healthy volunteers.Methods Sixty right-handed healthy male volunteers,aged 22-26,height 167-178 cm,weighing 51-67 kg,were randomly divided into 4 groups ( n =15 each): 15 degrees head-down tilt group (group Ⅰ ),30 degrees head-down tilt group (group Ⅱ ),15 degrees head-up tilt group (group Ⅲ) and 30 degrees head-up tilt group (group Ⅳ ).Blood flow signals of right middle cerebral artery (MCA) and extracranial internal carotid artery (EICA) were detected by transcranial Doppler and systolic blood flow velocity (Vs),diastolic blood flow velocity (Vd ),mean blood flow velocity (Vm),pulsatility index (PI) and resistance index (RI) were recorded at supine position (baseline),immediately,10 and 30 min after body position change(T1-3 ).Lindegaard index was calculated.Results Compared with the baseline,in group Ⅱ Lindegaard index was increased at T2,while Vs and Vm of MCA were decreased at T2,3,in group Ⅳ Vs of MCA and PI of EICA at T2,Vd and Vm of MCA at T2,3 were decreased ( P ＜ 0.05),while there was no significant difference in the variables mentioned above in the other two groups ( P ＞ 0.05 ).Conclusion In healthy adults,cerebral blood flow velocity decreases in 30 degrees headdown and head-up tilt positions,however there is no change in cerebral blood flow velocity in 15 degrees headdown and head-up tilt positions.