Studies on small intestinal obstruction. III. Circulatory effects of artificial small bowel distension

Feline small-bowel circulation was studied during in vitro homologous perfusion of denervated intestine, following artificial and successive elevation of the intraluminal pressure. The specimens were inflated with nitrogen in 20 mmHg increments to the 100 mmHg level. Each pressure level was maintained for a 10-minute period. After deflation the specimens were studied for a further 60 minutes. Blood flow, vascular resistance, capillary filtration, and oxygen consumption were significantly affected by the distension. In the post-distension period flow rate and vascular resistance remained on levels differing significantly from the control values, whereas capillary filtration and oxygen consumption reverted immediately to levels not differing from the control values. It is concluded that, in isolated and denervated small intestine of the cat, an elevated intra-intestinal pressure affects the consecutive vascular sections in a similar manner, probably by simple mechanical compression. Flow rate is reduced less than capillary filtration, suggesting an opening of short-circuiting shunts in the bowel wall. In the post-distension phase vascular resistance remains elevated, while the exchange circulation is rapidly and completely restored, suggesting an extensive closure of the short-circuiting shunts.