Research On Portable Measurement System Of Cardiovascular System Based On ARM

Cardiovascular disease is one of the heavy diseases which harm the human health, and World Health Organization has named it as the first killer of human health in the 21st century. It is essentially caused by structural or functional abnormity of blood vessel. The determination of physiological and pathological status of cardiovascular system at earlier period would help diagnose patient who is in an early stage,i.e. sub-clinical situation of cardiovascular disease and help prevent against it at this stage efficiently,which would bring great science and social value. Invasive methods have more precise information about cardiovascular status, but invasion and potential safety issue has limited their application. Therefore it is necessary and urgent to develop new technology and portable device for noninvasive cardiovascular measurement.Supported by Tianjin Innovation foundation (No. 05ZHCXGX12200), based on the methodology of cardiovascular fluid dynamics and wind kessel model, this thesis has performed investigation on the physiological and physical generation mechanism of the pulse wave of radial artery, the quantitative relationship between the pressure within blood vessel and the displacement of blood vessel wall in radial direction, and the characteristic parameter K derived from changes of pulse wave area. Finally, it is our aim to quantitatively reveal cardiovascular status with the parameters for blood pressure, blood flow, blood vessel and microcirculation.On the basis of the above methodology, in this thesis, a device for noninvasive cardiovascular measurement has been developed. The hardware of this device, based on ARM CPU (LPC2114), includes the modules of power supply, sampling, external memory, LCD and keyboard, USB communication, external timer. The softare of the device performs the identification of characteristic points, expert system, blood pressure measurement and USB communication. The pulse wave signal has been obtained by sensor, and then analyzed by LPC2114 after A/D conversion. Taking personal information of patient into an account, the device can calculate the measurement parameters of cardiovascular status. Scientific diagnosis can by displayed on LCD after furthered analyzed by expert system.The reliability and stability of the device has been verified through a set of experiments taking Arterial Stiffness Index (ASI) for example which reveals arterial stiffness. Twenty data sets have been collected from a volunteer. Results show that performance of the device presented is similar to the standard device(AZN-F cardiovascular function testing device). Therefore, the device presented could be used to determine the cardiovascular status and further would become an effective means to prevent cardiovascular diseases at their early stages.