The Study Of Noninvasive Continuous Detection Technology Of Blood Pressure

Blood pressure is one of the important physiological information of human body. It is also an important indice for preliminary judgment for clinical disease diagnosis, treatment effect of observation. Blood pressure is affected by a variety of factors. Single or discontinuity measurement works out a very different result. Therefore, the study of continuous blood pressure detection method has an important significance. The noninvasive continuous blood pressure measurement is not suitable for continuous blood pressure measurement in a long time, because of the complex equipment.In this article, we will use the photoelectric technology to detect the blood pressure of body continuously.A basic theory as we know that the volume of blood in body tissue is influenced cyclically by the periodic pulsation of the heart. So the light we receive on the receiver which actually is photodiode on the photoelectric sensor is cyclical change. Then we can obtain the photoelectric pulse wave signal(PPG) from electrical signals turned by light signals. In the process of getting PPG signals, we can not get the ideal signals for the extemelly thin electrical signal produced by photodiode combined with electronic components produced by thermal noise, the interference of magnetic field, the changes in ambient light and human factors such as breathing.Synthesis of the above, firstly, we design a pre-amplification electric circuit and a noise reduction circuit of the photodiode to process the signal. Secondly,we propose a method which the radius automatically match the moving average filtering preferentially after extracting the PPG signals,this removes high frequency noise effectively,including power frequency noise. Again, the mathematical morphology filtering method is proposed, which can effectively remove the baseline drift, and lay a good foundation for the blood pressure calculation. Finally, analyzing the correlation between the characteristics of the PPG signal and the blood pressure of the human body, a blood pressure calculating model based on PPG is constructed. At the same time, put forward the model based on a priori knowledge of the matching adaptive parameter tuning method, effectively reduce the individual differences and improve the non invasive blood pressure measurement accuracy based on PPG.The experimental results show that the method proposed in this paper can effectively removed the PPG signal contains noise, the experiment results show that, the measured results meet the AAMI standards, the method can use a noninvasive continuous blood pressure measurement.