Non-invasive Central Aortic Pressure Wave Monitoring System Based On Blind Identification TSML Algorithm

Central aortic pressure waveform can predict and evaluate cardiovascular diseases,and is thus of great significance.Compared with the peripheral ones,central aortic pressure waveform can more accurately reflect the status of human cardiovascular system.The commonly used central aortic pressure pulse wave measurement methods include invasive and noninvasive methods.The invasive measurement is expensive and is also painful and risky to the patient,while the existing noninvasive measuring devices cannot adequately account for the inter-individual variability.Therefore,this thesis designed and implemented a non-invasive monitoring system of central aortic pressure wave based on TSML algorithm of blind identification and an ARM platform.Unlike the systems based on transfer function method,this system implemented individually the non-invasive accurate measurement of the central aortic pressure without the need of a prior function or model.This thesis firstly designed the scheme of the overall system based on the objective and function of the system.In term of the hardware scheme,cuff pressure,shock wave,and pulse wave extraction circuits were designed.And the pneumatic system,analog-digital conversion circuit and power supply voltage conversion circuit were designed and components selected.As for the software scheme,there are two software parts:One is the implementation of the measurement of peripheral blood pressure based on variable amplitude coefficient method and the acquisition of peripheral pulse waveform on ARM platform,and another is the estimation of central pulse wave based on TSML algorithm on embedded system.Finally,in order to validate the accuracy and stability of this system,two experiments including the measurement of peripheral blood pressure and the estimation of central aortic blood pressure were performed.The brachial blood pressures of 48 young subjects were measured using both this system and the mercury sphygmomanometer.Compared with the mercury sphygmomanometer which is deemed as the standard,this system derives prediction errors of brachial systolic and diastolic blood pressure of-1.3±3.7mmHg and 1.6±4.OmmHg,which meets the 2010 AAMI Protocol.The stability of SBP and DBP were evaluated by Intra-class correlation(ICC).The ICC values were 0.95 and 0.84.The measurement of central aortic blood pressures of 20 young subjects was performed using both this system and the SphygomoCor system(AtCor,Australia),which is deemed as the standard.Compared with the SphygomoCor system,this system derives prediction errors of central aortic systolic and diastolic blood pressure of-1.8±4.5mmHg and 1.3±4.9mmHg.The ICC values were 0.93 and 0.91.Using this system,central aortic blood pressure is accurately and stably.