运用经颅多普勒超声对脑损伤血流动力学变化与脑顺应性关系的研究

目的：探讨脑血流动力学变化与脑顺应性的关系。方法：制作中、重度脑损伤动物模型，分别于伤后不同时相点用经颅多普勒超声（ＴＣＤ）仪探测猫大脑中动脉（ＭＣＡ）血流速度，计算搏动指数（ＰＩ），阻力系数（ＲＩ）及收缩峰与舒张期末血流速度比值（Ｓ／Ｄ），同时测量颅内压（ＩＣＰ）、容积压力反应（ＶＰＲ）及压力容积指数（ＰＶＩ），比较各指标间的关系。结果：脑损伤早期，ＭＣＡ血流速度增快，６小时后达高峰，以后逐渐减慢，２４小时后血流速度显著低于伤前；ＰＩ、ＲＩ及Ｓ／Ｄ值逐渐增大，２４小时后明显高于伤前（Ｐ＜０．０５）；损伤越重，变化越明显。ＩＣＰ、ＶＰＲ逐渐增大，ＰＶＩ降低。ＩＣＰ与收缩峰血流速度（Ｖｓ）、平均血流速度（Ｖｍ）、搏动指数（ＰＩ）及Ｓ／Ｄ值间有良好线性关系（Ｐ＜０．０１）；ＰＶＩ与Ｖｓ、舒张期末血流速度（Ｖｄ）、Ｖｍ及ＰＩ间有良好线性关系（Ｐ＜０．０１），但ＶＰＲ与ＭＣＡ各测量值间关系不明显。结论：ＴＣＤ仪能较好地反映脑损伤后血流动力学变化，以此可推测ＩＣＰ及脑顺应性的改变。

Transcranial Doppler for Comparative Studies on Relationship between Brain Hemodynamics and Compliance Following Brain Injuries

Aim: The objective of this article is to evaluate the changes of brain hemodynamics and to study the relationship of the changes between hemodynamics and compliance following traumatic brain injury (TBI) using transcranial doppler (TCD). Methods: The model of moderate and severe brain injury was made in cats. The blood velocity of middle cerebral artery (MCA) was measured with TCD after TBI. Pulsatile index (PI), resistance index (RI) and systolic peak/diastonic nadir (S/D) were calculated from TCD findings. Meanwhile, intracranial pressure (ICP), volume pressure reaction (VPR) and pressure volume index (PVI) were measured and calculated using ICP monitor. Results: The blood velocity of MCA became fast gradually after TBI, The peak value occurred at 6 hours after TBI, and tended to be lower after 6 hours and was even lower than that of pretrauma after 24 hours. The values of PI, RI and S/D increased gradually after TBI and were obviously higher than those of pretrauma after 24 hours ( P <0.05). The more severely the brain injured, the more obviously these values changed. ICP and VPR increased and PVI decreased after TBI. There was a positive linear correlation between ICP and systolic velocity , median velocity, PI, S/D ( P <0.01),and between PVI and Vs, diastolic velocity (Vd), Vm, PI ( P <0.01), but there was a negative relationship between VPR and these values above metioned. Conclusion: It is believed that TCD is useful in detecting the changes of hemodynamics after TBI and deducing the changes of ICP and compliance therewith.