The Development and Calibration of a Method for the Continuous Measurement of Stroke-Volume in the Experimental Animal

Intracardiac Pressure - Volume Diagrams and Their Links with Thermodynamics [Retrospectroscope]

“…The problem of detecting volume found a possible first answer by the application of the impedance technique in 1966 by a group led by Leslie A. Geddes, in Houston, Texas [14], [15]. Thereafter, and starting in the late 1970s, a Dutch team under the direction of Jan Baan introduced independently the conductance catheter as a more elaborate development, publishing a number of important papers of which, perhaps the most relevant, is one that appeared in 1984 [16].…”

Effects of respiration and vasodilation on venous volume in animals and man, as measured with an impedance catheter

“…However, measurements of the actual dynamics of venous volume and venous return in the intact circulation are more difficult. Previous studies of variations in vena caval or jugular flow have used various techniques, including differential manometers Previous reports have documented the utility of continuous on-line measurements of intracavitary electrical impedance in the determination of relative chamber vol-ume [19][20][21][22][23][24][25]. The use of this technique has been reported in the right and left ventricles and in the right atrium [25].…”

THE CARDlAC ELECTRICAL IMPEDANCE PULSE*

“…In clinical investigations, total or resistive impedance changes were correlated with pressure tracings, heart sounds, and cardiac output. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] Only two of those investigations correlated the direct measurements of resistive impedance over the chest with cardiac output determinations by the green-dye dilution method. In a study of 10 young men, the employed electrical impedance technique yielded stroke volume values 1.19 higher than obtained by the dye dilution method, while there was a 20% standard deviation from the best fit line.15J6 In a recent report, the correlation coefficient between the two methods was 0.68 in 13 normal subjects and 0.26 in 24 patients with heart disease.…”