Sahay K B, Mehrotra R, Sachdeva U, Banerji A K
Center for Biomedical Engineering, Indian Institute of Technology, New Delhi.
J Biomech. 1992 Mar;25(3):319-26. doi: 10.1016/0021-9290(92)90029-z.
The fluid-induced changes in the intracranial pressure which have important clinical implications are believed to be largely determined by the elastomechanical properties of the brain tissues. To define and evaluate the elastomechanical characteristics of the brain tissues a nonlinear hyperelastic hollow spherical shell has been employed to model the craniospinal complex for its fluid-induced intracranial pressure volume changes. The strain energy function proposed by Hart-Smith has been used to derive the constitutive equations. In 10 dogs, fluid has been infused in the lateral ventricle of the brain. The resulting changes in the ventricular fluid pressure (VFP) and the epidural pressure (EDP) have been recorded. The plot of pressure as a function of volume increases first, reaches a maximum, decreases, reaches a minimum and increases monotonously. The values of maximum and minimum pressures (pv max and pv min) due to fluid infusion are found to be, respectively, 42.4 +/- 15.4 mmHg and 33.1 +/- 12.2 mmHg. The pressure achieved the maximum and minimum values with infusion of 0.19 +/- 0.09 ml and 0.51 +/- 0.15 ml of fluid, respectively. The elastomechanical parameters of the Hart-Smith function that characterize the brain tissues have been evaluated by matching the experimentally obtained pressure-volume curves with the corresponding model generated curves. It is found that the agreement between the experimentally obtained pressure-volume curves and the corresponding Hart-Smith profile is satisfactory at a high inflation level but less so at the lower inflation level.
流体引起的颅内压变化具有重要的临床意义，据信这在很大程度上取决于脑组织的弹性力学特性。为了定义和评估脑组织的弹性力学特性，采用了非线性超弹性空心球壳来模拟颅脊复合体的流体诱导颅内压容积变化。利用哈特 - 史密斯提出的应变能函数推导本构方程。在10只狗身上，向脑侧脑室注入流体。记录由此产生的脑室液压力（VFP）和硬膜外压力（EDP）的变化。压力随容积的变化曲线先上升，达到最大值，然后下降，达到最小值，最后单调上升。发现因注入流体而产生的最大和最小压力值（pv max和pv min）分别为42.4±15.4 mmHg和33.1±12.2 mmHg。压力分别在注入0.19±0.09 ml和0.51±0.15 ml流体时达到最大值和最小值。通过将实验获得的压力 - 容积曲线与相应的模型生成曲线进行匹配，评估了表征脑组织的哈特 - 史密斯函数的弹性力学参数。结果发现，在高充盈水平下，实验获得的压力 - 容积曲线与相应的哈特 - 史密斯曲线之间的一致性令人满意，但在低充盈水平下则不太理想。
