经颅多普勒超声检测脑血流自动调节下限的初步应用

An pilot study on lower limit of cerebral blood flow autoregulation by transcranial Doppler ultrasonography

目的 研究经颅多普勒 (TCD)在脑血流自动调节下限检测中的应用 ,拓宽TCD的应用范围。方法 利用TCD检测SD大鼠大脑中动脉 (MCA)的血流速度 ,同步记录有创血压 ,按照临界关闭压 (CCP)的理论测定脑血流自动调节下限 ,与常用的缓慢放血降低血压 ,绘制脑血流自动调节曲线法测定的自动调节下限进行比较。结果 缓慢放血降低血压过程中 ,MCA的血流速度和颈总动脉的血流量下降趋势完全一致 (r =0 .95 116± 0 .0 5 736 ,P <0 .0 0 1) ,可以用MCA的血流速度代替血流量计算CCP。CCP法检测到的脑血流自动调节下限为 (70 .88± 2 4.0 5 )mmHg(1mmHg =0 .133kPa) ,与放血降低血压利用血流速度和血流量变化测定的结果 [分别为 (72 .88± 2 6 .2 6 )mmHg和 (75 .6 3± 2 2 .2 2 )mmHg]高度相关 (r分别为 0 .7945 5和 0 .73846 ,P均<0 .0 0 1) ,数值相近 ,来源于同一群体 (P分别为 0 .96 75 8和 0 .8176 8) ,前者可以代替后两者。结论 TCD检测MCA的血流速度 ,同步记录动脉血压 ,按照CCP理论测定脑血流自动调节下限 ,切实可行 ,结果可靠 ,可以准确、快捷地反映脑血流动力学变化。

Objective To study a new usage of transcranial Doppler (TCD) to assess the lower limit of cerebral blood flow autoregulation and widen the field of TCD.Methods The blood velocities of MCA were probed by transcranial Doppler in SD rat, and femoral blood pressure was recorded simultaneously by physiological multimeter. Then lower limit of cerebral blood flow autoregulation was figured out by the clinical closing pressure (CCP) and compared with the results obtainea by hemorrhage hypotension.Results In the process of hemorrhage hypotension, both of the velocity of MCA and the blood quality of common carotid artery were reduced, and the decreasing rate of velocity was almost equal to the one of blood quality (r= 0.951 16 ± 0.057 36 ,P< 0.001 ). So the velocity of MCA probed by TCD could replace the blood quality to calculate CCP. The lower limit of autoregulation of normal SD rats working out by CCP was ( 70.88 ± 24.05 )mm Hg(1 mm Hg= 0.133 kPa). It highly correlated to the results measured by hemorrhage hypotension [velocity of MCA:( 72.88 ± 26.26 )mm Hg and quality of CCA:( 75.63 ± 22.22 )mm Hg]. The latter should be replaced by the former.Conclusions The cerebral blood flow can be evaluated conveniently and exactly by lower limit of autoregulation figured out from MCA velocities and arterial blood pressure recorded simultaneously.