A study on Non-invasive Multifunctional Measurements of Circulatry Parameters Using Bio-electrical and Photo-plethysmography Techniques

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The present era, with accelerated aging of the population, has an increased need for early diagnosis and treatment of cardiovascular diseases such as heart disease, arteriosclerosis and cerebral apoplexy. For this purpose, there has been a requirement for simple and convenient instrumentation capable of quantitative evaluation of circulatory parameters. Non-invasive measurements which inflict little pain and/or injury are preferable in clinical use. Simultaneous measurement of physiological parameters with the least number of sensing techniques will also be more desirable for screening tests and home care use as well, which will provide an achievement of great social contribution. This research project conducted with such aims to provide a new simple technique for non-invasive and simultaneous physiological measurements based on our innovative sphygmomanometry called "volume-oscillometric(O) and volume-compensation (VC) method" and electrical admittance plethysmography(ADM) proposed pr … More eviously, and following significant results were successfully obtained. (1) A new simultaneous measurement of blood pressure,cardiac output,peripheral vascular resistance,and other important cardiovascular parameters has been proposed in combination of the VO or VC method and the ADM technique. A tetra-polar volume-clamp method has been newly designed for accurate and reliable detection of bio-electrical admittance signal. (2) Arlcrial elastic property in the human limbs has been successfully assessed as a function of blood pressure by measuring quantitavely blood volume changes with an infra-red photo-plethysmography and the ADM technique based on the VO method. (3) A new technique has been designed for the measurement of blood pressure as well as oxygenation of arterial and venous blood using a spectro-photometry based on the VO method. (4) An electrical admittance-cuff method has been newly proposed for the multifunctional and simultaneous measurement of blood pressure, blood flow, arterial and venous elasticity, haematocrit, capillary pressure, capillary filtration coefficient and so on in human limbs. With this method, several physiological findings were non-invasively revealed during exercise testing in terms of regulation of peripheral circulation. (5) Further developments such as long-term ambulatory cardiovascular measurements have been successfully progressed for clinical and home care use, obtaining considerably significant and interesting physiological findings which could not be got by conventional methods. Through these investigations, the present project would serve quite significant contributions in many fields of biomedical engineering, providing a practical multifunctional system for the non-invasive measurement and analysis of cardiovascular haemodynamics. Less