Effect of Catheter Sampling on the Shape of Indicator-Dilution Curves
Mean Concentration versus Mean Flux of Outflowing Dye
The dispersion of a very short bolus of dye carried through a long cylindrical tube by a Newtonian fluid has been investigated theoretically and experimentally for two situations. In the first case a short bolus of uniform length and concentration is considered, representing a uniform amount of dye entering the tube per unit cross-sectional area independent of velocity of flow at a particular radius from the tube axis. In the second case concentration is uniform so that layers of fluid with greater velocity will carry in more dye than slower layers. Since velocities at the tube wall approach zero whereas velocities of axial dye are maximal, the axial fluid will contain greater amounts of dye per unit area. The implication of these principles to the dispersion of dye taken from deeply situated sites in the mammalian circulation through catheters of appreciable volumue is discussed.
- Received May 29, 1959.
- © 1959 American Heart Association, Inc.