Considerations of the application of indicator dilution methods to the measurement of the flow rates of fluids

Abstract

In circumstances when the flow velocity of a fluid is non-homogeneous, difficulties arise in the application of the familiar indicator dilution equations. These and other relevant relationships were derived from first principles to clarify the conditions in which they may be expected to apply. The method of introduction of the tracer into a fluid stream and its method of measurement are important factors, and the implications of these results for biological measurements [cardiovascular application] are discussed. Illustrations are provided of the indicator dilution curves which are likely to be obtained under conditions of laminar fluid flow in a straight tube and when the diffusion of the tracer can be neglected.