Removal of Distortion from Indicator Dilution Curves with Analog Computer

Abstract

A method has been developed for characterizing quantitatively, and for removing from indicator dilution curves, the distortion introduced by catheter sampling systems. The method involves a specially constructed cuvette and analog computer analysis of the curves recorded by densitometers placed at the entrance of the catheter and at points downstream. This method of correction of distortion is based on a general theory of function transformation which is applicable to all situations and not upon empirically established constants which are only valid in special situations. The geometry (coiling, bending) of the catheter has been found to affect the distortion. Disruption of the flow pattern by insertion of a braided wire in the lumen causes less variation of the distortion caused by bending and coiling. Distortion was not significantly affected by change in blood temperature in our system.