Effect of correction of catheter distortion on calculated liver sinusoidal volumes

Abstract

The use of a collecting system to obtain samples in the multiple indicator-dilution technique produces delay in and distortion of the dilution curves. A method for removing these is described and the method is applied, using an analog computer, to previously published hepatic venous dilution curves (Am. J. Physiol. 204: 626, 1963). This correction increases with the rate of change of concentration and so is greatest for the labeled red cell dilution curves. The effect of the distortion on the previously described linear method for determining liver sinusoidal and extravascular volumes is described. Extravascular volumes of distribution of rapidly diffusible, completely recovered indicators (equivalent to transit-time volumes) are found to be unaffected, whereas catheter distortion is found, with the system used, to produce an increase in estimated sinusoidal blood volume of an average magnitude of 15%. These results suggest that the value obtained after removal of distortion of the collecting system is still in error by some amount of approximately the same order of magnitude because of the effect of portal and hepatic veins.