Study On Segmentation Characteristics Of Pulse Wave Transit Time

Pulse wave transit time(PWTT)is a very important physiological parameter of human body.In many studies,scholars try to use non-invasive technique to measure blood pressure.However,this technology shows great difference of users.Calibration for each particular user before it used greatly limits the use of technology.PWTT conduct a measurement based on time lag between R-wave crest of electrocardiogram(ECG)and feature point of photoplethysmography(PPG),this process includes Pre-ejection Period(PEP)and the transit time of pulse wave in arteries,arterioles and micro-arterioles but some parameters may not be related to blood pressure in the process.Therefore this paper conducts a study on segmentation characteristics of PWTT,and it is expected to improve the measurement method of non-invasive continuous blood pressure.The main contents of this research are as follows:(1)Research on the conduction conductivity of radial-finger pulse wave transit time,and this transmission process is micro-artery.Through the exercise experiment,synchronous acquired ECG signal,radial artery wave signal,finger pulse wave signal,to analyze variation tendency of radial-finger pulse wave transit time(rf-PWTT)during exercise.It turned out that radial artery pulse transit time(r-PWTT)and finger pulse transit time(f-PWTT)are high correlated with R-R interval(RRI).While there was little change of rf-PWTT during the whole exercise test,which showed a weak correlation with RRI.Thus deduced that r-PWTT is independent of blood pressure.(2)Research on ballistocardiogram(BCG)this signal represents the rhythmic movement of the heart,can evaluate of effect of PEP effectively.This paper presented and achieved device for measuring BCG based on acceleration sensor.The device is small,easy to wear,also it can synchronous measurement of ECG,BCG and finger PPG.The acquired BCG signal was preprocessed,which included remove the baseline and smooth filtering.And a method is presented for BCG signal feature extraction base on ECG and PPG,The results showed that the method can effectively extract J-wave of BCG feature.(3)Research on the change trend of BCG during recovery.Through the movement exercise experiment,and the ECG,BCG and finger PPG collected simultaneously.The extracted feature parameters are included heart rate(HR),PWTT,R-J interval(RJI),J-wave to pulse feature point interval(JPI)and amplitude of BCG,and researched correlation between the above characteristic parameters and HR.The results indicated that PWTT,RJI and amplitude of BCG are highly positively correlated with HR,while JRI showed a weak correlation with HR.(4)Research on the relationship between segmented transit time with blood pressure.The correlation analysis results showed that there was a significant correlation between blood pressure and PWTT or RJI for All the subjects,there was no correlation between JPI and blood pressure in some subject.Regression analysis showed,use PWTT and RJI parameters as the independent variable to estimate the blood pressure is better than that of using JPI parameters,and performance of PWTT and RJI is similar.Research results show that RJI can be used as a new index to calculate continuous blood pressure.