Friedrichs G S, Berger D S, Micheli-Tzanakou E
Department of Biomedical Engineering, Rutgers University, Piscataway, NJ 08855-0909.
J Biomed Eng. 1993 Jan;15(1):74-8. doi: 10.1016/0141-5425(93)90097-i.
ALOPEX is a general optimization process incorporating a cost function containing a large number of parameters which may be simultaneously adjusted until the cost function reaches an optimum (maximum or minimum); local extremes are avoided by introducing random noise into the procedure. In this paper, ALOPEX is incorporated into a simple haemodynamic study in which an electric analogue model of the left ventricle is used to develop equations of myocardial stroke work. Pilot experiments were undertaken in rabbits (n = 5) to gauge the effectiveness of this optimizing technique. In the control state, calculated stroke work for the rabbit was determined to be 50 +/- 7 mmHg ml, while ALOPEX predicted a stroke work of 51 +/- 7 mmHg ml. ALOPEX is capable of following changing cardiovascular states when pharmacological agents are introduced. For example, after nitroprusside treatment, stroke work was reduced by 38 +/- 6% (P < 0.05) while ALOPEX predicted a 42 +/- 4% reduction from baseline (P < 0.05). Methoxamine treatment increased stroke work by 74 +/- 34%, while ALOPEX predicted a 73 +/- 43% increase above control values. There were no statistical differences between calculated and ALOPEX predicted values. Individual model parameters such as maximum left ventricular elastance (Emax) and left ventricular end diastolic volume (EDV) were also predicted correctly by ALOPEX. We have found that the ALOPEX optimization technique is useful in predicting components of multi-parametric functions. In particular, we have shown it to be adaptable to a simple haemodynamic model.
ALOPEX是一种通用的优化过程，它包含一个成本函数，该函数包含大量参数，这些参数可以同时进行调整，直到成本函数达到最优值（最大值或最小值）；通过在过程中引入随机噪声来避免局部极值。在本文中，ALOPEX被纳入一项简单的血流动力学研究，其中使用左心室的电模拟模型来推导心肌搏功方程。在兔子（n = 5）身上进行了初步实验，以评估这种优化技术的有效性。在对照状态下，确定兔子的计算搏功为50±7 mmHg·ml，而ALOPEX预测的搏功为51±7 mmHg·ml。当引入药物制剂时，ALOPEX能够跟踪心血管状态的变化。例如，硝普钠治疗后，搏功降低了38±6%（P < 0.05），而ALOPEX预测从基线降低42±4%（P < 0.05）。甲氧明治疗使搏功增加了74±34%，而ALOPEX预测比对照值增加73±43%。计算值与ALOPEX预测值之间没有统计学差异。ALOPEX还能正确预测个体模型参数，如最大左心室弹性（Emax）和左心室舒张末期容积（EDV）。我们发现，ALOPEX优化技术在预测多参数函数的组成部分方面很有用。特别是，我们已经证明它适用于一个简单的血流动力学模型。
