Relation of colloid concentration to volume expansion for resuscitation of rats subjected to intestinal ischemic shock.

This study was undertaken to determine the volumes of colloids (albumin and dextran 40) with concentrations varying from 0% (Ringer's solution) to 10% solutions required to obtain the same hemodilution. Shock was produced in rats by exteriorization of the small intestine with added complete occlusion of the superior mesenteric vessels with a rubber clamp. After 1 h the clamp was removed, the intestines returned, and the abdomen closed. Over a 6-h period, the fluids were infused continuously in volumes needed to maintain similar hematocrit. Each concentration was given over a wide range of volumes in order to obtain volume-hematocrit curves. Based on these curves, the effect of varying colloid concentration on blood volume expansion was calculated. Albumin and dextran 40 had similar volume expansion/g colloid substance regardless of concentration. When hematocrit of 50% was chosen, as an arbitrary endpoint for volume infusion, the colloid concentration in relation to volume required to be infused is expressed by the equation F50 (formula: see text) where C = colloid concentration and where F50 is the volume factor, or the number of times the volume required for a 10% solution, when a 10% solution is given the volume factor of 1. This relationship is now being used to find the optimal colloid concentration with regard to survival rate in animals subjected to the same intestinal shock.