Department of Medical Physics, Medical College of Nanchang University, and Department of Special Diagnosis, The 94th Hospital of People's Liberation Army of China, Jiangxi, China.
Ann Biomed Eng. 2010 Mar;38(3):1007-16. doi: 10.1007/s10439-009-9886-8.
The purpose of this study is to investigate the mechanism of the formation for thoracic impedance change. On the basis of Ohm's law and the electrical field distribution in the cylindrical volume conductor, the formula about the thoracic impedance change are deduced, and they are demonstrated with the model experiment. The results indicate that the thoracic impedance change caused by single blood vessel is directly proportional to the ratio of the impedance change to the basal impedance of the blood vessel itself, to the length of the blood vessel appearing between the current electrodes, and to the basal impedance between two detective electrodes on the chest surface, while it is inversely proportional to the distance between the blood vessel and the line joining two detective electrodes. The thoracic impedance change caused by multiple blood vessels together is equal to the algebraic addition of all thoracic impedance changes resulting from the individual blood vessels. That is, the impedance changes obey the principle of adding scalars in the measurement of the electrical impedance graph. The present study can offer the theoretical basis for the waveform reconstruction of Impedance cardiography (ICG).
本研究旨在探讨胸腔阻抗变化的形成机制。基于欧姆定律和圆柱形容积导体中的电场分布，推导出了胸腔阻抗变化的公式，并通过模型实验进行了验证。结果表明，单个血管引起的胸腔阻抗变化与血管本身的阻抗变化与基础阻抗之比、出现在电流电极之间的血管长度以及胸腔表面两个探测电极之间的基础阻抗成正比，而与血管与连接两个探测电极的线之间的距离成反比。多个血管共同引起的胸腔阻抗变化等于单个血管引起的所有胸腔阻抗变化的代数和。也就是说，阻抗变化在阻抗图的测量中遵循标量相加的原则。本研究可为心阻抗图（ICG）的波形重建提供理论基础。
