Experimental studies on fluid pathophysiology in small intestinal obstruction in the rat. V. Effects of intraluminal hyperosmolality and simultaneous intravenous infusions on the experimentally obstructed and decompressed small intestine.

An influx of fluid into the lumen of the intestine similar to that seen in simple obstructional ileus may be provoked by introducing a hyperosmolal glucose solution into the bowel. In the otherwise intact small intestine the effect of this influx of fluid will be in accordance with a simple dilution curve. The intestinal mucosa thus functions in the manner of a semipermeable membrane permitting only hypo-osmolal fluids to enter the intestinal lumen and in amounts independent of parenteral fluid infusions, regardless of osmolality. This relationship persists even after the intestine has been totally obstructed for 3 days. The influx of fluid has the same principal characteristics, and the only limiting factor on the magnitude of this fluid shift to the intestine is the lack of fluids resulting from the marked dehydration of the organism due to ileus. Prerequisites for this are normal epithelial function and normal mucosal circulation. Thus it is clear that the organism in general and the small intestine in particular, even when exposed to prolonged obstruction, are still able to counteract intraluminal hyperosmolality by dilution with hypo-osmolal fluid.