Development Of A Portable Instrument For Assessing Cardiovascular Status

Cardiovascular disease is one of the three diseases which are threats to human life and health all over the world. In China, with the improvement of people’s living standards, the incidence of cardiovascular disease has drawn an increasing trend and the mortality rate also rises up year by year. The fundamental method that help to delay and control the cardiovascular disease is to apply early detection with effective interventions before its onset.Currently, the commercialized cardiovascular testing equipment has some common shortcomings such as large volume, high price and complex manipulation etc. A low-cost and portable device for monitoring and testing cardiovascular diseases is of great demands for home healthcare. Therefore, a portable cardiovascular condition assessment system is developed in this project, which mainly for community and home healthcare. It has advantages of small size, low power consumption, low cost, simple operation, and has the capacity of three-way pulse wave velocity values calculation and continuous blood pressure measurement. The primary features for the system design are summarized as follows:1. In the aspect of hardware, the project completed the hardware design and debugging of a portable system for cardiovascular condition assessment according to the design criteria. The system consisted of ECG extraction module, pulse extraction module, acquisition board and embedded module. Experimental results showed that the system could collect high-quality ECG and pulse signals and its performance could also meet the requirements for home healthcare.2. In the aspect of algorithm, a parameter extraction algorithm for cardiovascular condition assessment was developed, which was both effective and suitable for its implementation on the embedded module. It was able to perform signal preprocessing, feature point extraction, the calculation of pulse wave propagation velocity and the measurement and analysis of continuous blood pressure. For signal preprocessing, a novel approach was proposed based on the signal segmentation of ECG R-wave peak point to suppress baseline drift effectively. For feature point extraction, ECG R-wave peak point was detected and feature point of pulse wave was extracted successfully. For the calculation of pulse wave propagation velocity, by integrating multi-channel sensor signals, three-way pulse wave velocity values were calculated to assess the extent of atherosclerosis of the human body, which was a very important function of the system. For the measurement and analysis of continuous blood pressure, this thesis presents a novel method of establishing continuous blood pressure model, which combined the heart rate, pulse wave transit time, pulse wave contraction time and relaxation time and other parameters to establish the model of continuous blood pressure.3. In the aspect of software, the thesis achieved the software design of the portable cardiovascular condition assessment instrument, including the design of acquisition software of MCU, the design of human-computer interaction and the implementation of algorithm based on WINCE operating system.4. In the aspect of system validation and analysis, three experiments were conducted in the thesis. The results showed that the pulse wave velocity values were calculated by the instrument with high repeatability and high accuracy, and that the method of establishing continuous blood pressure model could establish a stable and effective blood pressure model. In addition, good consistency was also found between blood pressure values calculated using the developed system and those from the electronic sphygmomanometer. On all accounts, the developed system can be used for continuous monitoring of systolic and diastolic blood pressure.