The Radial Artery Systematic Modeling Based On Blood Pressure Analysis And Its Physiological Parameter Detection Method Study

In recent years,the study of central arterial pressure has become the increasingly important part of cardiovascular field,the cardiovascular research could play a vital role on preventing the daily disease,including hypertension,diabetics,dyslipidemia,and arteriosclerosis.In order to evaluate the cardiovascular research,we need to measure many subjects’ blood pressure and blood stream index,such as AIx,SBP,DPB,and so on.Our study has purposeful meanings in biomedical engineering field,during experiment we used a self-developed instrument arteriosclerosis detector to measure and obtain subjects’ data,in Beijing 301 hospital subjects were measured for radial artery and carotid artery parameters.In the overall project my job is to conduct the modeling analysis of the radial artery pressure waveform in our research team,including mathematical modeling and mechanical modeling,and associated test and result analysis based on the corresponding model.The content of mathematical modeling is to build the transfer function between radial artery waveforms and carotid artery waveforms;the contents of mechanical modeling are to analyze the vibration mechanics simulation and hemodynamics simulation of the radial artery model.Besides we also discussed the biomedical materials which could be used inside the radial vascular,and briefly introduced the two new materials graphene and two-dimensional transition metal oxides.Based on the above summary,the basic content of this paper includes the following sections:1.The impedance modeling and analysis of radial pressure waveformsThis section firstly established the vascular modeling of the peripheral artery,considering a basic impedance model to connect the relationship between the input blood stream and the output blood pressure.A frequency domain function was used to deduce the blood pressure from the blood stream.Secondly the ARX model and the ARMAX model were used to validate the radial artery waveform within its mathematical expression by Matlab software’s Identification tool,in order to have the appropriate order and delay to match radial pressure waveforms.Followly the Windkessel model was discussed furtherly,a classical model of vascular blood pressure raised by previous scholars.In Windkessel model the blood stream and blood pressure were supposed to the current and voltage in the circuit,the viscous resistance force was supposed to the resistance in the circuit,the vascular compliance was supposed to the capacitance in the circuit.The classical Windkessel model could be one-order Windkessel or the third-order Windkessel,the first-order Windkessel has one capacitor in parallel with one resistance,the third-order Windkessel has two capacitors in parallel with one resistance.The first-order Windkessel considers one small section of the radial artery vascular,while the third-order Windkessel take the blood circulation and the central artery-peripheral artery association into account to build a more complicate model.Based on the impedance modeling,this thesis raised the carotid-radial artery waveform transfer function in frequency domain furtherly.2.The carotid-radial transfer functions and mathematical modeling of blood pressure waveformsCarotid-radial transfer function is based on clinical need for non-invasive detection,the pulse wave sensor was built based on applanation tonometry method,which is commonly used method of estimating the peripheral arterial pressure wound.However,because the carotid artery are deeply buried and relatively mobile,it is difficult for us to obtain and measure the signal by our sensor,coupled with the pressure measured time if the subject of the carotid artery would subject discomfort.Carotid artery waveform can be calculated from easily measured radial artery waveform and generalized transfer function(generalized transfer function,GTF).The GTF is firstly raised by the scholars from the John Hopkins University,constructed and verified in Europe population in early period.In the construction of the transfer function,we measured the carotid and radial artery waveform from 60 subjects,and summarized these waveforms in our database,seeking the associate mathematics relationship from carotid and radial artery waveform signal waveform signals by matlab program,and amplitude ratio and phase difference is extracted from Fourier transformation,and finally the normalized frequency-domain transfer function is constructed.3.Mechanical parameters modeling of the radial arteryAccording to our experiments,we can analyze the influence of various factors influence the blood waveform of blood flow from the blood pressure and the physiological signals,such as hypertension.Comparing to the waveform analysis,the author also conducted the mechanical parameter modeling of radial artery.In mechanical parameter modeling we derived the relationship of the blood pressure and all the parameters revealing in physical derivations.By theoretical derivations and ANSYS simulation we combined the theoretical part and the actual measured waveforms together,investigating blood pressure’s influence on radial waveforms.Besides,the two mechanical computing methods were discussed in the later part of this section,the finite element method and the mesh-free method.The finite element method is a common-used computing method by dividing the initial structure into micro mesh for calculation.Comparatively the mesh-free method used shape function to avoid meshing grids and its serial problems,using a more optimizing means for calculation.Comparing to the finite element method,the mesh-free method has novelty and higher efficiency.4.The vibration analysis and hemodynamics analysis of radial vascularAdditionally we conducted the radial vascular ’s vibration analysis for the stenosis condition and normal condition respectively,demonstrating the strain contour and the vibration frequency from the first-order to the third-order.We used ANSYS software to accomplish the mode and strain contour of the radial vascular in rigid status.Besides we discussed the new biomedical materials which could be used in vascular applications,graphene.Based on the afore mechanical analysis,in order to investigate the blood’s influence inside the radial artery vascular,the hemodynamics analysis for four stenosis condition considering the flowing blood was then conducted:20%stenosis condition,50%stenosis condition,75%stenosis condition,90%stenosis condition.We used Gambit software to build the modeling and meshing of the vascular,the following numerical solution and calculation was conducted in Fluent.Our hemodynamics analysis focused on the stenosis condition and the normal condition of the radial artery respectively,observing the influence of stenosis within different levels on the flow velocity contour and the pressure contour.