Bastiaanssen E H, van Leeuwen J L, Vanderschoot J, Redert P A
Dept. of Physiology, Leiden University, Netherlands.
J Theor Biol. 1996 Jan 21;178(2):113-33. doi: 10.1006/jtbi.1996.0011.
A biomechanical model of the lower urinary tract which is able to respond to input signals from a neural network is presented. The neural input is the starting point in the description of the relationships between the various physical parameters in the mechanical model of the bladder and the urethra. The cybernetics of the lower urinary tract are described on the basis of the muscle dynamics of simple models of both the detrusor in the bladder wall and the urethral sphincter. The urethral sphincter is not described as a variable resistance, like in other biomechanical models of the lower urinary tract, but is described on the basis of striated muscle dynamics. The forces produced by the detrusor and the urethral sphincter give rise to the bladder pressure and the urethral pressure. Using quasi-steady assumptions, the flow rate of urine is calculated as a result of the pressure difference between the bladder and the urethra. Parameters like the bladder volume, the flow rate and the pressure in the bladder can be compared with clinical data of urodynamic measurements. Simulation results show that the model is able to mimic both a filling and an emptying behaviour which resembles the behaviour of the lower urinary tract. By increasing the resistance of the urethra, a behaviour model of the lower urinary tract appears which is comparable with the pathology of urethral obstruction. A sensitivity analysis of various parameters in the model leads to a better understanding of the biomechanics of the lower urinary tract.
本文提出了一种能够响应神经网络输入信号的下尿路生物力学模型。神经输入是描述膀胱和尿道力学模型中各种物理参数之间关系的起点。基于膀胱壁逼尿肌和尿道括约肌简单模型的肌肉动力学来描述下尿路的控制论。与其他下尿路生物力学模型不同，尿道括约肌并非被描述为可变阻力，而是基于横纹肌动力学进行描述。逼尿肌和尿道括约肌产生的力导致膀胱压力和尿道压力。利用准稳态假设，根据膀胱和尿道之间的压力差计算尿液流速。膀胱容积、流速和膀胱压力等参数可与尿动力学测量的临床数据进行比较。模拟结果表明，该模型能够模拟类似于下尿路行为的充盈和排空行为。通过增加尿道阻力，出现了一种与尿道梗阻病理情况相当的下尿路行为模型。对模型中各种参数的敏感性分析有助于更好地理解下尿路的生物力学。
