Lodi C A, Ursino M
Department of Electronics, Computer Science and Systems, University of Bologna, Italy.
Ann Biomed Eng. 1999 Mar-Apr;27(2):257-73. doi: 10.1114/1.168.
A mathematical model of cerebral hemodynamics during vasospasm is presented. The model divides arterial hemodynamics into two cerebral territories: with and without spasm. It also includes collateral circulation between the two territories, cerebral venous hemodynamics, cerebrospinal fluid circulation, intracranial pressure (ICP) and the craniospinal storage capacity. Moreover, the pial artery circulation in both territories is affected by cerebral blood flow (CBF) autoregulation mechanisms. In this work, a numerical value to model parameters was given assuming that vasospasm affects only a single middle cerebral artery (MCA). In a first stage, the model is used to simulate some clinical results reported in the literature, concerning the patterns of MCA velocity, CBF and pressure losses during vasospasm. The agreement with clinical data turns out fairly good. In a second stage, a sensitivity analysis on some model parameters is performed (severity of caliber reduction, longitudinal extension of the spasm, autoregulation gain, ICP, resistance of the collateral circulation, and mean systemic arterial pressure) to clarify their influence on hemodynamics in the spastic territory. The results suggest that the clinical impact of vasospasm depends on several concomitant factors, which should be simultaneously taken into account to reach a proper diagnosis. In particular, while a negative correlation between MCA velocity and cross sectional area can be found until CBF is well preserved, a positive correlation may occur when CBF starts to decrease significantly. This might induce false-negative results if vasospasm is assessed merely through velocity measurements performed by the transcranial Doppler technique.
提出了一种血管痉挛期间脑血流动力学的数学模型。该模型将动脉血流动力学分为两个脑区：有痉挛和无痉挛的区域。它还包括两个区域之间的侧支循环、脑静脉血流动力学、脑脊液循环、颅内压（ICP）和颅脊髓储存容量。此外，两个区域的软脑膜动脉循环都受脑血流量（CBF）自动调节机制的影响。在这项工作中，假设血管痉挛仅影响单一的大脑中动脉（MCA），给出了模型参数的数值。在第一阶段，该模型用于模拟文献中报道的一些临床结果，涉及血管痉挛期间MCA速度、CBF和压力损失的模式。与临床数据的吻合度相当好。在第二阶段，对一些模型参数进行敏感性分析（管径减小的严重程度、痉挛的纵向延伸、自动调节增益、ICP、侧支循环阻力和平均体动脉压），以阐明它们对痉挛区域血流动力学的影响。结果表明，血管痉挛的临床影响取决于几个伴随因素，为了做出正确诊断，应同时考虑这些因素。特别是，在CBF得到良好维持之前，可以发现MCA速度与横截面积之间呈负相关，而当CBF开始显著下降时，可能会出现正相关。如果仅通过经颅多普勒技术进行的速度测量来评估血管痉挛，这可能会导致假阴性结果。
