DocumentCode :
1223602
Title :
The Impedance Plethysmographic Sampling Field in the Human Calf
Author :
Penney, Bill C. ; Narducci, Lorenzo M. ; Peura, Robert A. ; Anderson, Frederick A., Jr. ; Wheeler, H.Brownell
Author_Institution :
Biomedical Engineering Program, Department of Life Science, Worcester Polytechnic Institute
Issue :
4
fYear :
1979
fDate :
4/1/1979 12:00:00 AM
Firstpage :
193
Lastpage :
198
Abstract :
Impedance plethysmography has been widely used clinically because of its convenience and sensitivity, but its use has been questioned by some investigators because of uncertainty concerning the source of the signal. Quantitative definitions of the sensitivity to conductivity changes as a function of position have been lacking. The present study defines the sampling efficiency for impedance measurements made with four electrodes on a uniform cylinder model of the calf. Predictions based on electric field theory compare favorably with results from an in vitro model (average rms error = 8 percent). These studies demonstrate that for a given voltage electrode separation, the proximity of the current electrodes determines the relative sensitivity to conductivity changes within the sampling field. For voltage and current electrode separations of 10 and 18 cm on a 37 cm circumference calf (typical measurements for clinical testing of the lower leg), the sampling field extends about 3 cm beyond the voltage electrodes and the deep vessels are sampled with at least 80 percent of the efficiency of the superficial vessels. These studies also indicate that it is possible to predict the sampling field associated with various electrode configurations, a possibility which should aid the design of electrode configurations for specific applications of impedance plethysmography.
Keywords :
Conductivity; Current measurement; Electrodes; Humans; Impedance measurement; In vitro; Plethysmography; Predictive models; Sampling methods; Voltage; Blood Vessels; Electric Conductivity; Humans; Leg; Models, Biological; Plethysmography, Impedance; Vascular Resistance;
fLanguage :
English
Journal_Title :
Biomedical Engineering, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9294
Type :
jour
DOI :
10.1109/TBME.1979.326557
Filename :
4123029
Link To Document :
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