Research Of Dynamic Blood Pressure Measurement And Parameter Calibration Based On Photoplethysmography

According to statistics from health-care departments, the number of death from hypertension and its complications has amounted to 2,000,000. Nowadays, what is most frequently used is the single-point measurement based on the cuff inflation and deflation.Cuff-less continuous blood pressure measurement is becoming the development trend of blood pressure.To address this issue, the thesis proposes a continuous blood-pressure measurement based on Photoplethysmographic(PPG), which is not only convenient and comfortable, but also available for continuous measurement of beat-to-beat blood pressure.In the thesis, a set of dynamic blood-pressure measurement system is designed on the stm32 hardware platform including one electrocardiogram(ECG) signal and two PPG signals. Blood pressure is calculated according to the linear relationship between Pulse Transmit Time(PTT) and the blood pressure. The experiment compares series of characteristics of PPT and selects prime feature points related to blood pressure. Then we study on weather the relationship formula between PTT and blood pressure is commonly applicable and whether it changes with time. After a relevance comparison between PPT and 24-hour static blood pressure, we put forward three calibration schemes, with which we could conduct timing correction through oscillometric blood pressure meter and measure testees’blood pressure with better accuracy. This has turned out to be plausible and feasible to monitor 24-hour dynamic blood pressure.In the experiment, we come to the following conclusions:firstly, the relevance between PPT and blood pressure generated by dual PPG feature points obviously outperforms others; secondly, the relation curve between the PPT and blood pressure of one individual gradually changes with time; thirdly, the relevance of PPT with blood pressure after sports exercises is more salient than that with static blood pressure; fourthly, blood pressure with better accuracy could be attained if standard blood pressure could be corrected at a regular and fixed time.