| In the field of clinical care, Pulse Wave Transit Time (PWTT) is regard as animportant physiological parameter, which is able to express many cardiovascularparameters such as changes in blood pressure, obstructive sleep apnea-hypopneasyndrome, arterial compliance, arteriosclerosis and respiratory effort. The aboveparameters are especially important for burn, psychiatric and elderly patients. However,the conventional methods collect PWTT in a contact way, which makes it inconvenientand sometimes impractical to collect the R-wave in the electrocardiogram as the beginningof PWTT collection.The bioradar technology has experienced a rapid development in recent years. It hasspecial value in clinical care due to the unparalleled advantages of being non-contact andunconstrained to patients. Based on this fact, it is hoped that the deficiency of contactmeasurement methods can be filled up through non-contact collection of the beginning of PWTT by bioradar technology, combined with fingertip pulse wave.This paper mainly focuses on PWTT extraction based on bioradar. The heart beatwave is acquired by non-contact bioradar technology. Then the peak of the wave is takenas the start time point of PWTT and the fingertip pulse wave is considered to be the endtime point. PWTT is calculated as the difference of the two time points.The following work has been done in this project:1. By comparative analysis of human ECG and heart beat gram, it was found thatPWTT measured by the ECG R-wave method was disturbed by pre-ejection period (PEP).Different from the mechanism of electrical signal of human body, the mechanical notioncurve of heart beat was able to well eliminate the interference of PEP.2. The experimental system of non-contact PWTT collection based on bioradar wasestablished, which was composed of bioradar, respiratory sensor, pulse senor, ECGacquisition module and multi-channel polygraph. The system was connected to a computerand data was analyzed by Matlab and MedCalc. The experiment collect and analysis of theheart rate to debug system and adjust the distance of the bioradar.3. In order to compare PWTT collected by contact and non-contact methods,synchronization accuracy between channels during multi-channel comparativeexperiments must be guaranteed. Therefore verification experiment of systemsynchronization was designed and completed, in which multi-channel signal collectionwas done and correlation analysis as well as phase difference calculation were completed.The results showed that the synchronization accuracy met the requirements of PWTTerror.4. PWTT collection of a number of subjects and comparative analysis were done.PWTT was synchronously collected using R-wave-gated Pulse Wave Transit Time(RWPWTT) and bioradar method. Bland-Altman analysis was done and the resultsshowed that there was good consistency between both methods.5. Comparative experiments between PWTT based on bioradar technology andreal-time blood pressure (BP) were designed. Through comparative analysis theconclusion that there was a strong correlation between PWTT and BP was verified. Moreover, the feasibility of clinical non-contact PWTT measurement based on bioradartechnology was demonstrated.The innovation of this paper:1. A new method of non-contact PWTT measurement based on bioradar wasproposed.2. PWTT collected by conventional ECG R-wave method was disturbed by PEP,which could be effectively eliminated by PWTT measurement based on bioradartechnology.3. The method of waveform maxima extraction using wavelet transform wasproposed. |
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