VALIDATION OF NON-INVASIVE CARDIOVASCULAR MONITORING SYSTEM MAKING USE Of THE TECHNOLOGY TO REALIZE THE ENVIRONMENT OF INNER HUMAN BODY AT OUTSIDE HUMAN BODY

本研究对最近发展起来的三种典型血压测量方法：示波式自动血压计、利用脉搏波传播时间的腕表式血压计和光电脉搏波监护仪进行24小时血压监测的有效性进行了研究。重点研究了脉搏波传播时间与人体实际血压准确性的关系。为此，我们考虑了模拟人体血压测量实际情况的边界条件的影响。首先，设计并加工了一种设备，用于精确模拟人体上臂在血压测量过程中的压力脉动行为和血管的振动特性。该设备由软管、驱动脉搏波的活塞-曲柄机构和维持平均血压的头部水箱组成。其次，通过改变挠性管的阻力和收缩来测量各种类型的脉搏波形。同时，我们基于可折叠管道的物理模型，考虑了管道的刚性和边界条件的影响，开发了计算机程序来精确地模拟血管的行为。利用硅管的实验数据验证了程序的有效性。然后将该程序应用于人体血管，首先得到了合理的结果，可以解释人体动脉测量结果的趋势；此外，我们还成功地建立了薄柔性结构与流动流体之间流体结构相互作用的计算方法，其中流体力的非线性是重要的，给出了非线性在这一问题中所起作用的物理解释。

This study is concerned with the validation of recently developed three kinds of typical blood pressure measurement methods such as oscillometric auto blood pressure meter, wristwatch type blood pressure meter utilizing pulse wave traveling time and photoelectric pulse wave monitor to observe blood pressure over 24 hours. We mainly focused on the relation between pulse wave traveling time and the accuracy of actual blood pressure of human body. Therefore, we took account of the effect of boundary condition simulating real situation of human blood pressure measurement.First, we designed and machined an equipment to simulate precisely the behavior of the pressure pulsation and the vibration characteristics of blood vessel of an upper arm of a human body during blood pressure measurement which consists of flexible tube, piston-crank mechanism for driving pulse wave and head tank to maintain average blood pressure. Secondly, we measured various types of pulse waveform by changing resistance of a flexible tube and constrictions. Simultaneously, we developed computer code to simulate the behavior of the blood vessel precisely based on the physical model of the collapsible tube taking account of the effect of rigidity of the tube and boundary conditions. Validity of our program was checked by experimental data using silicon tube. Then, we applied this program to human blood vessels and we first succeeded in obtaining reasonable results which can explain the trend of measured results with human arteries.Furthermore, we succeeded in formulating the method of calculation concerned with fluid structure interaction between thin flexible structure and the flowing fluid where non-linearity of the fluid force is important, which gives us the physical interpretation of the role of nonlinearity in this problem.