Effects of Infusion Rate and Osmolarity on Volumogenic Diarrhea

A study was performed in dogs to elucidate the effects of infusion rate and osmolarity on the onset of diarrhea induced by infusing fluid into the upper gut (volumogenic diarrhea). With isotonic saline the diarrhea-inducing volume was largest at low infusion rates. This volume declined sharply with increasing infusion rates up to 30 ml per min, and remained unchanged at 61.5 ± 1.7 ml per kg of body weight, with rates between 30 and 900 ml per min. The volume of hypertonic sorbitol which induced diarrhea was not significantly different from that of saline at infusion rates exceeding 30 ml per min. At infusion rates below 30 ml per min, a smaller volume of sorbitol than saline was required to induce diarrhea. When saline was infused at rates below 30 ml per min, absorption of more than 20'7 of the infused volume occurred and increased the diarrhea-inducing volume. With sorbitol solution at low infusion rates, enterosorption of fluid amounting to as much as 411 < of the infused volume kept the diarrhea-inducing volume fairly constant at 62 ± 2.7 ml per kg of body weight. It was found that, as the body weight of the dogs increased, the total volume necessary to produce diarrhea also increased.