Experimental Studies on Fluid Pathophysiology in Small Intestinal Obstruction in the Rat

Abstract

Using an experimental model in rats and a hyperosmolal solution introduced into the intestinal lumen as an activating factor, an accumulation of fluid in the intestine similar to that seen in simple obstructional ileus has been produced and accentuated. After 3 days of intestinal obstruction, the intestinal mucosa still retains its selective ability to allow the passage of hypo-osmolal fluid into the intestinal lumen. If the contents of the obstructed intestine are removed before the hyperosmolal solution is introduced, unaltered conditions are maintained when parenteral fluids are administered, regardless of their osmolality. If the accumulated fluid was permitted to remain in the intestine, so that the experimental hyperosmolal solution was added to the contents of the intestine, developments followed a diphasic course. In the first phase the increase in volume and reduction in osmolality of the intestinal contents took place as in the intact intestine and with identical effects on hemoconcentration and serum osmolality. During the latter phase of the test period the increase in volume ceased, and there was a tendency to a decrease with coincident inverse changes in the osmolality of the intestinal fluid. Volume developments in the intestinal lumen were not significantly affected by giving parenteral fluids, although there was a reduction in hemoconcentration. Serum osmolality was affected only by hypo-osmolal infusions. Apparently the level of intraluminal osmolality at which absorption began was determined by the level of serum osmolality.

Key-words:

• Body fluids
• intestine
• small
• intravenous infusions
• osmolar concentration
• rat