Thoracic impedance change equation deduced on the basis of parallel impedance model and Ohm's law.
OBJECTIVE
The aim of the present study is to investigate an impedance change equation suited with the measurement of the impedance cardiograph (ICG).


METHODS
Based on a parallel impedance model and Ohm's law, an impedance change equation differed from Nyboer's equation is deduced. It is verified with the experiments of the impedance cardiography in 100 healthy adults.


RESULTS
This equation shows that the thoracic impedance change (ΔZ) is directly proportional to the value of the volume change (ΔV) of the blood vessel, to the ratio of the basic impedance to the body height (Z(0)/H), while it is inversely proportional to the square of the chest circumference (C(t) (2)). These are supported by the experimental results in the measurement of the ICG.


CONCLUSIONS
The equation proposed in the present paper is coincident with the actual condition in the measurement of the ICG.
Department of Special Diagnosis, 94th Hospital of People's Liberation Army of China, Jiangxi Nanchang, China.
Xiao
X
Qiu-Jin
Wang
W
Zhen
Kuang
K
Ming-Xing
Wen
W
Ping
Liu
L
Pei
Ji
J
Jian-Feng
D049628:Body Size / Q000502:physiology*; D002302:Cardiac Output / Q000502:physiology*; D002307:Cardiography, Impedance / Q000379:methods*; D003198:Computer Simulation; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D017097:Electric Impedance; D006801:Humans; D008955:Models, Cardiovascular; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013909:Thorax / Q000502:physiology*