DEVELOPMENT OF BLOOD PRESSURE DATA ACQUISITION SYSTEM MAKING USE OF THE TECHNOLOGY TO REALIZE THE ENVIRONMENT OF INNER HUMAN BODY AT OUTSIDE HUMAN BODY

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This study is concerned with the mechanism of blood pressure measurement and the argument on the accuracy of the measured results. 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. Experimental parameters we mainly focused on are average pressure level, amplitude of pressure pulsations and the range of observed blood vessel vibrations i.e. the initiation and vanishing point of vibration and corresponding average blood pressure level.We also 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. Comparisons between calculated and experimental results are made and the reasonable agreement is obtained. In addition, we conducted a basic research to develop 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 first treated and the limit cycle oscillation is first derived by calculation. This method is anticipated to become a tool to analyze the dynamic characteristics of blood vessels and vane in near future.