Venegas J G
Department of Biomedical Engineering, Massachusetts General Hospital, Boston.
Am J Physiol. 1991 Aug;261(2 Pt 1):C355-63. doi: 10.1152/ajpcell.1991.261.2.C355.
This paper presents the theoretical basis for estimating the detrusor's viscoelastic properties using the small-amplitude oscillatory perturbations technique. Three possible configurations of the simplest second-order lumped-parameter model of the bladder were analyzed to derive equations of the parameters incremental resistance (R) and incremental elastance (K) in terms of the experimentally measurable magnitude and phase of hydrodynamic stiffness. In model I, single viscous, elastic, and inertial elements were assumed to to be connected in series. In model III the elastic and viscous elements were connected in series, but the inertial element was connected in parallel. With the assumption of a spherical geometry of the bladder, equations were also derived to obtain the bladder wall mechanical properties, spring incremental constant (S), and muscle incremental viscosity (b) as functions of bladder volume and the hydrodynamic properties R and K. Integration of the incremental equation describing the viscous component yields an expression that fits well the force-velocity experimental data from bladder strips reported by others. This finding suggests that muscle viscosity measured with the small-amplitude oscillations and analyzed with the proper theoretical model may be related to the force-velocity characteristics of the muscle. The equations delivered here form the basis for analyzing the experimental data described in the companion paper.
本文介绍了使用小幅度振荡微扰技术估算逼尿肌粘弹性特性的理论基础。分析了膀胱最简单的二阶集总参数模型的三种可能配置，以根据流体动力刚度的实验可测量幅度和相位推导参数增量阻力（R）和增量弹性（K）的方程。在模型I中，假设单个粘性、弹性和惯性元件串联连接。在模型III中，弹性和粘性元件串联连接，但惯性元件并联连接。假设膀胱为球形几何形状，还推导了方程，以获得膀胱壁力学特性、弹簧增量常数（S）和肌肉增量粘度（b）作为膀胱体积以及流体动力特性R和K的函数。描述粘性成分的增量方程的积分产生了一个与其他人报告的膀胱条带力-速度实验数据拟合良好的表达式。这一发现表明，用小幅度振荡测量并用适当的理论模型分析的肌肉粘度可能与肌肉的力-速度特性有关。本文给出的方程构成了分析配套论文中描述的实验数据的基础。
