多导生物电阻抗胃动力检测机制评价研究

The impedance signal measured from body surface has some relevance to gastric motility and empting. The electrical bioimpedance technique is used for assessment of gastric motility by injecting alternating current and measuring the potential difference via cutaneous electrodes from abdominal area. The physiological and pathological information can be extracted when the electrical characteristics of the stomach changes. This method has the advantage of being noninvasive and convenient, and it can provide functional information. But as an indirect measurement method, the quantitative relationship between impedance signals and gastric motility is still unknown and needs further exploration. Furthermore single channel bioimpedance measurement method is still often used at present which can not reflect the peristalsis in different regions of the stomach. The scientific problems will be researched in this project including the quantitative relationship between the electrical impedance signals from body surface and the gastric motility, and the propagation characteristic of the gastric peristaltic wave. A three dimensional finite element model will be established using COMSOL software for simulating the conductivity distribution of upper abdomen, and the conductivity variations during the propagation of the peristaltic waves produced by gastric contraction will be obtained. A multichannel electrical impedance measurement system for gastric motility will be build and used for experiment in a specially designed device and human medical experimentation. The device includes a tank filled with salt solution, agar and mechanical movement parts to simulate gastric contraction. The control experiment will be carried out using multichannel impedance measuring system and POLYGRAF ID gastrotonometer for comparison. These simulations and experiments research methods mentioned above will be used to demonstrate the correlation and quantitative relationship between the electrical impedance signals and the gastric motility. The characteristic of the multichannel electrical impedance signals in time and space which reflects propagation process of gastric peristaltic wave will be researched at the same time. The aim of this project is to obtain the measurement mechanism of the electrical impedance method for gastric motility, and create a no-invasive and efficient evaluation methodology for gastric motility in clinic.

腹部体表测量电阻抗信号与胃运动和胃排空存在一定的相关性。生物电阻抗胃动力检测通过体表电极注入微小电流，利用胃运动产生电学变化特性，测量电阻抗变化信息获取胃动力学特性及其变化规律，该方法无创、廉价、方便。但作为一种间接测量方法，体表电阻抗信号与腹内胃运动之间的定量关系尚不明确；现有方法多为单导电阻抗测量，反映的是胃蠕动引起的电阻抗变化总和在体表的投影。本申请拟建立多导体表电阻抗测量系统，获取不同部位的胃动力变化信息；采用三维电学仿真、装置模拟实验、体表多导电阻抗测量与多点胃内压力测量对照实验相结合的研究方法，分析电阻抗信号与胃不同部位收缩幅度的定量关系；确定胃消化过程中，胃的电导率、体积、位置等影响因素变化对体表电阻抗的影响与定量关系；获取多导电阻抗信号的空间和时相传播规律；通过仿真和实验研究，明确电阻抗胃动力检测的测量机制，为胃动力功能检测基础研究和临床应用提供更为全面、有效的评价手段。

生物电阻抗胃动力检测通过体表电极注入微小电流，利用胃运动产生电学变化特性，测量电阻抗变化信息获取胃动力学特性及其变化规律。为了明确体表测量电阻抗信号与腹内胃运动之间的关系，建立了基于真实人体数据的三维仿真模型，进行了电特性仿真研究；构建了多导电阻抗胃动力检测系统，包括硬件电路与上位采集软件，优化了体表检测电极阵列结构，开展了人体实验研究；设计了胃动力测量模拟实验装置，进行了琼脂模型、螺旋模型和胃排空动态模拟实验研究。结合仿真和实验研究，进行了电阻抗胃动力测量影响因素的评价，对消化过程中胃内食物的导电性、胃的体积、胃收缩腔闭合程度和波宽变化等因素，定量分析了多个通道电阻抗测量值的变化。在胃的体积和位置不变的条件下，电导率增大时，各通道边界测量电压均呈下降趋势，电压变化率随电导率的增大逐渐减小。当胃容积增大时，高电导率胃内容物的边界测量电压降低，低电导率胃内容物的边界测量电压升高，电压变化率随胃容积的增大而减小。对于高电导率胃内容物，体表电压信号的幅值随胃收缩幅度（包括腔闭合程度和波宽）的增大而升高。电阻抗测量信号的幅值变化，与上述因素成非线性单调变化关系，受到上述因素的综合影响。结合胃收缩蠕动引起的电场分布变化规律及测量电极检测灵敏度分布规律，分析了多导体表电阻抗信号与腹内胃不同部位运动的相关性，研究了胃运动的时间、空间传导机制，结果表明多通道电阻抗测量能够反映由于胃收缩传导引起的局部阻抗的变化，信号的频率反映胃不同部位的收缩节律和传播速度，多个测量通道间的波形存在明显的相位差，反映了胃收缩蠕动的空间传导过程。应用多尺度分析、复杂网络分析等非线性信息处理方法，研究了胃阻抗信号传播特征，为胃肠病患者胃动力的疗效评价提供了新的有效参数。本研究的仿真与实验结果，明确了电阻抗胃动力检测的测量机制，为阻抗胃动力测量方法提供了理论支持，为多通道阻抗胃动力测量系统的设计提供了实验依据。