Plasma Volume Changes Compared With Hematocrit and Plasma Protein Changes After Infusion

Abstract

Plasma volume changes calculated from hematocrit dilution after dextran and saline infusions into anesthetized dogs were compared with direct measurements of plasma volume by the iodinated albumin method. Large infusions and consequent large increases in plasma volume result in hematocrit changes indicating greater plasma volume changes than are found by the direct determination of plasma volume when the measurements are made soon after the end of the infusion. This difference is directly related to the magnitude of the plasma volume change. Four hours after the infusions, both methods yield similar values. Data is also presented to support the validity of the dilution principle for the measurement of plasma volume.