An Electrical Analogue for Analysis of Tracer Distribution Kinetics in Biological Systems

Abstract

An electrical analogue for the analysis of tracer distribution kinetics in compartmental biological systems is described. These systems are simulated by a network of five-decade resistors and five-decade capacitors cycled with a 1.5-second period. Voltage curves from the analogue capacitors are compared directly with graphically plotted tracer concentration curves with high accuracy. Adjustment of analogue elements for correspondence between such voltage and concentration curves allows accurate values of the system interconnection and of tracer volumes of distribution and flow rates to be rapidly obtained. The application of the machine to analysis of concentration curves obtained from human subjects with ascites and/or edema is described. Finally, modifications of the apparatus are discussed which make it applicable where transient flow between volumes or transfer with differing forward and back flow rates is present.