A Detection System Of Brachial Artery Endothelial Function Based On Bioelectrical Impedance

Cardio-and cerebrovascular diseases have become the illness with highest mortality rate.Improving efficiency of the early diagnosis and monitoring the disease is one of the important ways to reduce cardio-and cerebrovascular diseases.Atherosclerosis is one of the independent risk factors of these diseases.Its early stage is the arterial endothelial dysfunction.The cardio-and cerebrovascular dysfunction can be diagnosed in the early by assessing the brachial artery endothelial function quantitatively,which leads to the early diagnose of the cardio-and cerebrovascular diseases,and provides with some evidences for a new early treatment.At present,the clinical evaluation of brachial artery endothelial function is mainly to detect brachial artery blood flow-mediated-dilation(FMD)by using a color Doppler ultrasound.Although this technique has higher resolution and accuracy,it has disadvantages including expensive equipment,low portability,complicated operations,and bulky,and is not easy to applied in the community or at home.To overcome these disadvantages,a detecting and analyzing system for assessing brachial artery endothelial function based on bioelectrical impedance is proposed in this thesis.The main works are:(1)A method for detecting and analyzing the brachial artery endothelial function based on the principle of bioelectrical impedance technique is proposed.First,the bioelectrical impedance signal of the forearm is detected,and analyzed by using the wavelet transform to further extract the three characteristic parameters,including characteristic peak frequency,average amplitude and average energy,at the frequency band(0.01Hz~0.1Hz)for the physiology activity of arterial endothelial cells,in order to assess the physiological status of endothelial function;(2)With the abovementioned method,a detecting and analyzing system of brachial artery endothelial function based on bioelectrical impedance is designed,which consists of three parts,i.e.,software design,hardware implementation,and data analysis.First,The forearm bioelectrical impedance signal is preprocessed and then transported to the personal computer(PC)via the USB interface for the further data analysis.And it is also connected with a smart phone via the bluetooth.Thus,the online detection and local detection is realized;(3)Using the desinged system,the forearm bioelectrical impedance signals before and after the moderate-intensity exercise are collected and further analyzed with wavelet analysis.The results show that comparing with the resting state,the frequency of the characteristic peaks remains almost the same after the exercise intervention,while the average amplitude and average energy decrease obviously,indicating that the vascular diameters increases and representing the diastolic characteristics of brachial artery endothelium after the exercise intervention.These characteristics are consistent with those obtained by detecting FMD based upon the color Doppler ultrasound technique,which validates the feasibility of tthe detecting and analyzing system.Comparing with the current method by detecting FMD based upon the color Doppler ultrasound,the detecting and analyzing system of brachial artery endothelial function based on bioelectrical impedance proposed in this thesis is noninvasive,harmless,cheap,easy-to-operate,easy-to-carry and easy acceptable.It can be used in the community or at home for the monitoring and the online detecting and provides with a base for the further development of the intelligent wearable system for detecting brachial artery function based upon bioelectrical impedance technique.