从胸部体表混合阻抗变化中分离出主动脉、肺部动脉和心室阻抗变化分量的研究

Now the impedance carciography （ICG）is generally measured with Kubicek's method or Sramak's method, and suppose that the ICG is an impedance change, which evokes from the volume change of the aorta. But many studies have confirmed that the ICG measured by the these methods is kind of the mixed impedance change,which mainly evokes from the volume changes of the aorta, arteries in lungs and ventricles. Obviously, the cardiac function results obtained with this method include not only the left heart effects, but also include the right heart effects. This method lacks the correct physiological base for evaluating the cardiac function of left ventricle, and the measurement reliability is lower.This is a fundamental problem which is not solved in long time for the research field of the international electrical bio-impedance. This study try to solve the above problem through that the impedance change components for aorta, artery in left lung, artery in right lung, left ventricle and right ventricle are separated from the mixed impedance changes measured on the chest surface. Ite main reseach contents are that: the formatiom mechanism of the impedance change measured on the chest surface is investigated, the method that the thoracic mixed impedance changes are measured with more leads is seeked, thoracic impedance equations for separation are established,the above impedance change components are obtained through solving this equations,these compneonts are demonstrated with the animal expenriment, an expenriment equipment for the waveform separation is developed, the various impedance change components for the normal adults and patients are measued，and the waveform parameters of various components are calculated statistically. The expected aim of this study is that: the non-uniqueness problem in the measurement of the ICG is solved, the correct theoretical base is established for the reseach and applition of the ICG.

目前心阻抗图一般用Kubicek法或Sramak法测量，并把它看作是主动脉容积变化引起的。但大量研究表明，这些方法测得的心阻抗图是由主动脉、肺部动脉和心室等容积变化共同产生的混合阻抗变化。用该方法得到的心功能结果既有左心的作用，又有右心的作用，用于评价左室心功能，缺乏正确的生理学基础，测量的可靠性较差，这是国际电生物阻抗研究领域内长期未解决的基础性问题。本课题设想，通过从胸部体表混合阻抗变化中分离出主动脉、左侧肺部动脉、右侧肺部动脉、左心室、右心室的阻抗变化分量来解决上述问题。研究内容是：胸部体表混合阻抗变化形成的机理，多导联检测胸部混合阻抗变化的方法，胸部阻抗方程组的建立，求解方程组得到上述各阻抗变化分量，并用动物实验验证，研制波形分离实验装置，测量和统计正常人和患者各分量的波形参数。本课题预期目标是：解决心阻抗图测量中长期存在的非唯一性问题，为心阻抗图的研究和应用奠定正确的理论基础。

大量研究已证明，传统心阻抗图是一种由主动脉、肺部血管和心室等容积变化共同产生的混合阻抗变化，它既有左室的作用，又有右室的作用，用于测量左室心功能，缺乏唯一性，测量结果的可靠性较差，这是国际电生物阻抗研究领域内长期没有解决的基础性问题。本课题立项的目标是从胸部体表混合阻抗变化中分离出AO、PL、PR、LV、RV的阻抗变化分量，解决上述非唯一性问题。本项目计划任务书中有七点具体研究内容，现已全部完成，归纳起来可分为三个方面：①胸部体表混合阻抗变化形成机理的探讨：建立了胸部圆柱形容积导体电场分布的物理模型，分析了胸腔中血管阻抗变化转换为胸部体表两检测电极之间电压变化的机理。据此分别导出了单根血管和多根血管在胸部体表产生阻抗变化的公式，并被圆柱体盐水容积导体的静态阻抗模型实验所证实。②胸部体表混合阻抗变化分离方法的研究：基于上述两个阻抗变化公式，建立了胸部圆柱体阻抗测量模型，构建了包括五个未知阻抗变化分量和六个方程组成的胸部阻抗变化分离方程组，用逐次逼近代数重构迭代法求解，从胸部体表混合阻抗变化中分离出了AO、PL、PR、LV、RV五个阻抗变化分量，其可行性为10条狗的动物实验和800多例人体测量结果所证实。③胸部体表混合阻抗变化分离实验装置的研制，有三个研究内容：第一、胸部体表混合阻抗变化测量的六导联方式，由3个电流电极和12电压检测电极组成；第二、测量硬件，主要由高频恒流源、阻抗、心电、心音测量电路、计算机、A/D转换卡、医用直流隔离电源、导联线等组成；第三、测量软件，主要包括同步采集和显示、选择标志点、除去呼吸波、求解胸部阻抗变化分离方程组、测量波形参数、显示测量结果、存盘和读盘等程序。测量结果表明，各阻抗变化分量能够分别间接地反映胸腔中各大血管和心室的生理活动过程。因此，本项目解决了心阻抗图测量中长期存在的非唯一性问题，为心阻抗图的临床应用搭建了一个新的平台，达到了预期的研究目标。