Mechanism of the Formation for Thoracic Impedance Change

Abstract

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).

Comparing square root method of measuring the cardiac output by means of aortic impedance change component to Kubicek's method

“…To solve the above problem of non‐uniqueness, we separated the impedance change components of AO, PL, PR, LV and RV from the mixed impedance changes measured on chest surface . The waveform graphs of these components indirectly reflect the processes of the physiological activity of the corresponding blood vessels and ventricles in the thorax .…”

“…To solve the above problem of non-uniqueness, we separated the impedance change components of AO, PL, PR, LV and RV from the mixed impedance changes measured on chest surface. [26][27][28] The waveform graphs of these components indirectly reflect the processes of the physiological activity of the corresponding blood vessels and ventricles in the thorax. 28 The C wave amplitude ðdZ=dtÞ AO Cmax and ejection time T s in the square root formula are obtained from the AO differential graph of the RICG, and the cardiac output computed with this formula is that of the LV.…”

“…In order to solve the above problems, a number of researches were made in the academia of electrical impedance graph . Regarding the first inadequacy mentioned above, we separated the impedance change components of the aorta (AO), blood vessels in the left lung (PL), blood vessels in the right lung (PR), left ventricle (LV), and right ventricle (RV) from six mixed impedance changes measured on the chest surface through waveform reconstruction . The waveform graphs of various components obtained by the above separation are collectively called reconstructed impedance cardiography (RICG).…”

“…[17][18][19][20][21][22][26][27][28] Regarding the first inadequacy mentioned above, we separated the impedance change components of the aorta (AO), blood vessels in the left lung (PL), blood vessels in the right lung (PR), left ventricle (LV), and right ventricle (RV) from six mixed impedance changes measured on the chest surface through waveform reconstruction. [26][27][28] The waveform graphs of various components obtained by the above separation are collectively called reconstructed impedance cardiography (RICG). Regarding the second inadequacy mentioned above, we deduced a thoracic impedance change equation in which the chest circumference was one of the variants.…”

Waveform analysis of differential graphs of reconstructed impedance cardiography from healthy individuals

“…In order to solve this problem, we have derived five impedance change components corresponding to aorta (AO), left lung vasculature (PL), right lung vasculature (PR), left ventricle (LV), and right ventricle (RV) from six mingled impedance changes measured on the chest surface through waveform separation (Kuang et al, 2010;Ming-Xing, Qiu-Jin, Nan-Zhen, Chao-Ying, & Ai-Rong, 2011). The waveform graphs of these components are collectively referred to as reconstructed impedance cardiography (RICG).…”