Stergiopulos N, Meister J J, Westerhof N
Biomedical Engineering Laboratory, Swiss Federal Institute of Technology, Ecublens.
Ann Biomed Eng. 1994 Jul-Aug;22(4):392-7. doi: 10.1007/BF02368245.
We derived and tested a new, simple, and accurate method to estimate the compliance of the entire arterial tree and parts thereof. The method requires the measurements of pressure and flow and is based on fitting the pulse pressure (systolic minus diastolic pressure) predicted by the two-element windkessel model to the measured pulse pressure. We show that the two-element windkessel model accurately describes the modulus of the input impedance at low harmonics (0-4th) of the heart rate so that the gross features of the arterial pressure wave, including pulse pressure, are accounted for. The method was tested using a distributed nonlinear model of the human systemic arterial tree. Pressure and flow were calculated in the ascending aorta, thoracic aorta, common carotid, and iliac artery. In a linear version of the systemic model the estimated compliance was within 1% of the compliance at the first three locations. In the iliac artery an error of 7% was found. In a nonlinear version, we compared the estimates of compliance with the average compliance over the cardiac cycle and the compliance at the mean working pressure. At the first three locations we found the estimated and "actual" compliance to be within 12% of each other. In the iliac artery the error was larger. We also investigated an increase and decrease in heart rate, a decrease in wall elasticity and exercise conditions. In all cases the estimated total arterial compliance was within 10% of mean compliance. Thus, the errors result mainly from the nonlinearity of the arterial system. Segmental compliance can be obtained by subtraction of compliance determined at two locations.
我们推导并测试了一种新的、简单且准确的方法，用于估计整个动脉树及其各部分的顺应性。该方法需要测量压力和流量，并且基于将双元件风箱模型预测的脉压（收缩压减去舒张压）与测量的脉压进行拟合。我们表明，双元件风箱模型准确地描述了心率低谐波（0 - 4次）时输入阻抗的模量，从而能够解释动脉压力波的总体特征，包括脉压。该方法使用人体全身动脉树的分布式非线性模型进行了测试。计算了升主动脉、胸主动脉、颈总动脉和髂动脉中的压力和流量。在全身模型的线性版本中，在前三个位置估计的顺应性与实际顺应性的偏差在1%以内。在髂动脉中发现误差为7%。在非线性版本中，我们将顺应性的估计值与心动周期的平均顺应性以及平均工作压力下的顺应性进行了比较。在前三个位置，我们发现估计的顺应性与“实际”顺应性之间的偏差在12%以内。在髂动脉中误差更大。我们还研究了心率增加和降低、血管壁弹性降低以及运动状态等情况。在所有情况下，估计的总动脉顺应性与平均顺应性的偏差在10%以内。因此，误差主要源于动脉系统的非线性。通过减去在两个位置确定的顺应性，可以获得节段顺应性。
