Continuous Blood Pressure Measurement Based On The Pulse Of The Fingers

In recent years,with the development of medical equipment detection technology,digital medical equipment has been widely used in people's daily life.Now smartphones are becoming more and more powerful,and it plays an important role in people's daily life,and it is becoming more and more popular to monitor people's physical status through mobile phones.At present,obtaining the photoelectric volume pulse wave signal(PPG)through the mobile phone camera is a research hotspot.It uses the mobile phone's optical sensor,the powerful computational ability,does not need the extra equipment to obtain the heart rate,the respiration,the HRV,the blood oxygen,the blood pressure and so on physiological parameter.Pulse wave signals contain many physiological and pathological information related to cardiovascular system,and the characteristic changes of pulse wave can reflect the state of human physiological system.The detection of vital signs parameters has become a hot topic in smart medical research.Pulse wave signal,as an important sign parameter,is closely linked with various chronic diseases and cardiovascular diseases.Now people can use the convenience of mobile phones to detect pulse wave signals anytime and anywhere,so that they can have a clear understanding of their physical condition.This thesis uses mobile phone camera to collect finger PPG signal,by denoising the PPG Signal,the pretreatment PPG signal is determined periodically and the characteristic points representing different physiological meanings are positioned,and the correlation between the systolic pressure(SBP)and the diastolic blood pressure(DBP)is selected by the multiple group characteristic parameters.The regression equation of blood pressure was established by stepwise regression analysis and the application program was developed on the Android system.The specific contents of this thesis are as follows:1.Using mobile phone camera to capture video images of changes in finger brightness and shade,the amplitude of grayscale value or PPG signal is obtained from the frame image.Analyzing the original PPG signal collected,a FIR digital low-pass filter is designed to remove high-frequency noise;and a morphological filter is used to suppress the base-line drift of PPG signal.2.The dynamic threshold method is used to determine the cycle of the processedPPG signal.Then we select and locate the characteristic points which represent different physiological states in PPG signal,then choose the appropriate characteristic parameters,analyze the correlation between the characteristic parameters and the systolic and diastolic pressure,and finally pass the characteristic parameters and the contraction pressure,The diastolic pressure was analyzed by stepwise regression,and the regression equation between the characteristic parameter and the blood pressure value was obtained.3.This thesis designs the software of measuring blood pressure based on the Android platform,verifies the practicability and reliability of the proposed method,verifies the error of the measured blood pressure value and the real value by using the PPG signal collected by the mobile phone and calculating the characteristic points and the characteristic parameters.By verifying that the measured blood pressure and the actual value of the error to meet the United States Medical Devices Association(AAMI)to assess the accuracy of the standard sphygmomanometer.