The effect of anesthesia and laparotomy on blood flow to the stomach, small bowel, and colon of the dog.

The effect of anesthesia and laparotomy on the distribution of blood flow to the different tissue layers of the stomach, small bowel, and colon of the dog was studied using a double-isotope, microsphere technique. In conscious dogs total jejunal flow significantly exceeded both ileal and colonic flow. Mucosal flow comprised about two thirds of total gastric and small bowel flow, but less than half of colonic flow. Fifteen minutes after induction of anesthesia, there was a marked increase in flow to all levels of the alimentary tract, as well as to each tissue layer. This increase was transient, since by 1 hour flow to all gut levels had decreased nearly to baseline levels. Laparotomy per se did not significantly alter blood flow to the full thickness or mucosal layer of either stomach, small bowel, or colon. These findings indicate that future studies of gut function or blood flow should be performed in conscious animals or in anesthetized animals only after complete cardiovascular stabilization. Neither laparotomy nor anesthesia caused a redistrubtion of flow away from the mucosal layers, and hence the observation that patients have often stopped bleeding at the time of operation for uncontrolled hemorrhage is unexplained.