Variations of Transthoracic Electrical Impedance in Relation with Hemodynamic Changes of Pulmonary Circulation

Abstract

Applying electrodes on bilateral chest walls, variations of electrical impedance were recorded during breath holding under various manipulations of the pulmonary hemodynamics with dogs. Pulsatile variations of the impedance recorded either directly from lobe surfaces or chest walls were in constant coupling with ECG and pressure waves in the pulmonary artery. These impedance pulses and their first differential derivatives decreased their height and area when the pulmonary blood flow was decreased, and increased those when the flow was increased. These changes disappeared when the manipulations were released and they returned to the original shapes. These results suggest that the impedance measurement on the chest wall gives informations concerning changes of pulmonary circulatory dynamics and can possibly be employed as a non-traumatic and continuous monitoring techninque for the pulmonary blood flow both experimentally and clinically.