桡动脉血压模型的系统建模及其生理参数检测方法研究

发布时间：2018-09-08 06:46

【摘要】：近些年来,中心动脉压的研究成为了心血管疾病学术领域中备受关注的重要部分,通过对心血管疾病的研究可以预防一些日常的生理疾病,比如高血压、糖尿病、血脂异常、动脉硬化等。为了评估心血管疾病,需要测试很多受试者的血压血流指标,比如增长因子AIx、收缩压SBP、舒张压DBP等。本研究对于生物医学工程方面有着针对性的意义,在实验中测试者使用了中科院智能所自行开发的仪器,并驻点北京301医院对各种病人进行测试,从而获得病人的各种桡动脉、颈动脉特征参数值。本人的工作是在团队中做桡动脉血压波形的系统建模分析,包括数学建模、力学参数建模以及在相应模型基础上进行相关的测试和分析。其中数学建模的内容是,通过颈动脉到桡动脉之间的血压关联求传递函数;力学参数建模的内容是,通过对桡动脉血管模型进行血压、血流的基本理论推导,补充了桡动脉血管的振动力学分析和血流动力学分析。论文的基本内容主要包括以下部分:1.桡动脉血压波形的阻抗建模和分析本节首先构建桡动脉的血管模型,首先推导最基本的阻抗模型,这个阻抗模型是用于关联桡动脉血管内部血压和血流之间的关系,用一个频域的函数通过血流推导血压。其次用ARX模型和ARMAX模型来验证对于桡动脉脉搏波血压波形的数学表达式,通过matlab软件的系统辨识工具箱获取对于波形的拟合效果,推出合适的阶次和时延以更好的拟合桡动脉血压波形。之后作者进一步讨论了弹性腔模型,一个前人学者构建的对于血压波形的经典模型。弹性腔模型把血管的血压和血流假想成电路中的电压和电流,把血管内部的粘滞阻力假想成电路中的电阻,把血管内部的顺应性假想成电路中的电容。经典的弹性腔模型有一阶模型和三阶模型,一阶模型是在电路中用一个电容器和一个电阻并联,三阶模型是在电路中用两个电容器和一个电阻并联。一阶模型是考虑血管片段式的简单模型,三阶模型是考虑血压循环的结合中心动脉和外周动脉之间关联而构建的更为复杂的模型。本文对弹性腔模型的讨论是为了探讨桡动脉脉搏波频域分量的内涵。在阻抗建模的基础上,论文进一步提出了构建桡-颈动脉脉搏波血压波形的频域传递函数。2.颈-桡动脉传递函数和血流血压波形的数学建模颈-桡动脉传递函数是根据无创检测的临床需要而构建的,在桡动脉脉搏波血压波形的获取中首先要使用到基于张力测定法的脉搏波传感器,由于颈动脉埋藏较深并且相对移动,致使传感器不好测量、信号采集困难,加之测量的时候需要按压受试者的颈动脉会给受试者带来不适,所以颈-桡动脉脉搏波传递函数的构建有着重要的意义,颈动脉的脉搏波波形可以通过桡动脉脉搏波波形和传递函数来获取。颈动脉波形可以通过广义传递函数计算,目前这种广义传递函数方法最早是由美国约翰霍普金斯大学的学者提出,开始主要在欧洲人群中构建并验证。本研究初次在中国人群中使用了广义传递函数方法,测量了 60个受试者的颈动脉和桡动脉波形,并在数据库中汇总,再通过matlab程序来求颈动脉波形信号和桡动脉波形信号之间的数学关联,进行傅里叶变换之后求得幅值和相位,计算幅值比和相位差,最后得到归一化的频域传递函数。3.桡动脉的力学参数建模根据实验测得的血压生理信号,可以分析各种因素对于血压血流波形的影响。相比较于实测的波形信号分析,研究者还做了关于桡动脉的力学参数建模的研究工作。其主要内容是通过桡动脉血管的力学模型推导,让血压信号与各种参数之间的关系物理化,以便于进行生物力学分析。通过理论推导和ANSYS的力学仿真,我们把理论推导和仿真图、实验波形结合起来,分析血压等因素对于桡动脉波形的影响。在此基础上,探讨了两种常用的力学计算方法,分别是有限元方法和无网格方法。有限元方法是常用经典方法,通过对一定的结构划分网格获取最小的基本单元进行力学求解。而无网格方法是通过使用形函数来回避划分网格引起的一系列问题,用更优化的计算方法来求解。相比之下,无网格方法更加新颖、计算效率更高。4.桡动脉血管的振动分析和血流动力学分析论文最后做了桡动脉血管在动脉狭窄和正常血管两种状态下的振动力学分析和血流动力学分析。振动力学分析考察了前三阶振动模态下的振动力学云图和振动频率,用ANSYS软件做了血管在刚性状态下(不考虑血液流动)的模态和应变云图,并进一步讨论了可以用于血管内部的生物材料,主要是新兴的生物材料包括石墨烯等。此外,为了探究微观状态下血管内部血液流动的不同影响,作者更深入的进行了桡动脉血管四组动脉狭窄状态下的血流动力学分析:20%狭窄状态、50%狭窄状态、75%狭窄状态、90%狭窄状态,运用Gambit软件做好血管的建模和网格划分,再用Fluent软件进行流体分析,判断不同程度下桡动脉血管动脉狭窄的特征对于血流的速度和压强云图有着什么样的影响。
[Abstract]:In recent years, the study of central arterial pressure (CAP) has become an important part of cardiovascular disease research. Through the study of cardiovascular diseases, we can prevent some daily physiological diseases, such as hypertension, diabetes, dyslipidemia, arteriosclerosis and so on. Flow indices, such as growth factor AIx, systolic blood pressure SBP, diastolic blood pressure DBP, etc. This study has a specific significance for biomedical engineering. In the experiment, the testers used the instruments developed by the Institute of Intelligence of the Chinese Academy of Sciences, and were stationed in Beijing 301 Hospital to test various patients, so as to obtain the characteristics of the patients'radial artery and carotid artery. My work is to do systematic modeling and analysis of radial artery blood pressure waveform in a team, including mathematical modeling, mechanical parameter modeling and related testing and analysis based on the corresponding model. The main contents of this paper are as follows: 1. Impedance modeling and analysis of radial artery blood pressure waveform. In this section, we first build a radial artery model, first push forward. The basic impedance model is used to correlate the relationship between blood pressure and blood flow in the radial artery. The blood pressure is derived from the blood flow by a function in the frequency domain. After that, the author further discussed the elastic cavity model, a classical model of blood pressure waveform constructed by predecessors. The elastic cavity model assumes the blood pressure and blood flow of the blood vessels as voltage and current in the circuit, and the blood flow is assumed to be blood. The classical elastic cavity model has a first-order model and a third-order model. The first-order model uses a capacitor and a resistor in parallel in the circuit. The third-order model uses two capacitors and a resistor in parallel in the circuit. The first-order model is a simple model which considers the vascular fragments, and the third-order model is a more complex model which considers the blood pressure circulation and the relationship between the central artery and the peripheral artery. Frequency domain transfer function for constructing radial-carotid pulse wave blood pressure waveform is proposed. Because the carotid artery is deeply buried and relatively moving, the sensor is difficult to measure, and the signal collection is difficult. In addition, when measuring, it is necessary to press the carotid artery of the subject, which will bring discomfort to the subject. Therefore, the construction of the carotid-radial pulse wave transfer function is of great significance. The carotid pulse waveform can be passed through the carotid artery. Carotid artery waveforms can be calculated by generalized transfer function (GTF). The GTF method was first proposed by researchers at Johns Hopkins University in the United States and was primarily constructed and validated in European populations. The waveforms of the carotid and radial arteries of 60 subjects were measured and summarized in the database. The mathematical correlation between the waveforms of the carotid and radial arteries was obtained by MATLAB program. After Fourier transform, the amplitude and phase were obtained, the amplitude ratio and phase difference were calculated, and the normalized frequency domain transmission was finally obtained. Function 3. The mechanical parameter modeling of radial artery can analyze the influence of various factors on blood pressure and blood flow waveform according to the physiological signals of blood pressure. Compared with the measured waveform signal analysis, the researcher has also done the research work on the mechanical parameter modeling of radial artery. Through theoretical derivation and ANSYS mechanical simulation, we combine theoretical derivation with simulation diagram and experimental waveform to analyze the influence of blood pressure and other factors on radial artery waveform. Finite element method and meshless method are used to solve mechanics problems. Finite element method is a classical method to obtain the smallest basic element by meshing a certain structure. 4. Vibration analysis and hemodynamics analysis of radial artery under two states of arterial stenosis and normal blood vessels are done. Vibration mechanics analysis of radial artery under the first three vibration modes is investigated. Dynamic nephogram and vibration frequency were used to make the modal and strain nephogram of blood vessel in rigid state (without considering blood flow) by ANSYS software, and further discussed the biomaterials which can be used in blood vessel interior, mainly the new biomaterials including graphene and so on. With the same effect, the author made a more in-depth analysis of the hemodynamics of four groups of radial artery stenosis: 20% stenosis, 50% stenosis, 75% stenosis, 90% stenosis. Gambit software was used to model and mesh the vessels. Fluent software was used to analyze the flow of radial artery in different degrees. The characteristics of pulse stenosis affect the blood flow velocity and pressure cloud picture.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：R54

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