Experimental studies on fluid pathophysiology in small intestinal obstruction in the rat. III. Effects of intraluminal iso-osmolality and simultaneous intravenous infusions.

The introduction of a hyperosmolal glucose solution in the intestinal lumen in an experimental model using rats resulted in the accumulation of large quantities of fluid in the lumen, resembling the situation in simple obstruction of the small intestine. To establish whether the osmotic strength of the glucose solution caused this influx of fluid, or whether the volume of the fluid per se is a contributory factor, an identical amount of an iso-osmolal and largely non-resorbable substance was introduced in place of the hyperosmolal glucose solution. No influx of fluid into the intestinal lumen could be demonstrated even when large infusions of varying osmolality were given intravenously. The osmolality of the intestinal contents remained unchanged as well as the intraluminal pressure. Despite the massive infusion of fluids, the hematocrit remained relatively stable, thus indicating stable blood volume and demonstrating the enormous storage capacity of the extravascular compartment.