Development of noninvasive measurement of peripheral circulation and its medical application

Surveys were carried out on tissue blood flow measurement based on the thermal diffusion method and on the assessment of peripheral circulatory function using photosensors.Regarding the thermal diffusion method, first noninvasive measurement using a Peltier stack was carried out. Then, measurements using a thermal clearance curve at various temperatures were performed.For noninvasive measurement of the mechanical properties of peripheral arteries using photosensors, the author determined the vascular volume ratio and/or the relative vascular volume.For clinical application in field studies, it is necessary to develop an apparatus with which absolute evaluation of the intravascular volume can be carried out using the blood volume around the unit volume as an indicator. Therefore, an apparatus that removes a signal constituent from tissue other than the blood using two-wavelength photosensors is required.If a noninvasive method to accurately measure the intravascular volume is established, changes in the mechanical properties of the peripheral arteries that correspond to functional and organic changes in the normal response can be observed more directly. Moreover, quantitative assessment of peripheral circulatory function will become possible, and diagnosis of the severity of peripheral circulatory disorders will be facilitated.