慢性小腸イレウス時の消化管運動変化に関する実験的検討

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Changes in the diurnal motor activity of the stomach, duodenum and small intestine were recorded continuously for several weeks by extraluminal force transducers in six conscious dogs with a reversible mechanical partial small bowel obstruction (chronic ileus model). An occluding instrument devised to allow extracorporeal manipulation in conscious animals was fixed to the mid-small intestine to create and release partial obstruction. Dogs were fed once a day at 17 o'clock. Under normal conditions, there were two major activities with interdigestive and digestive patterns, and these patterns were modulated after feeding. The interdigestive pattern (fasting pattern) was characterized by a cyclic generation of bursts of strong contractions called "interdigestive migrating contractions" (IMC) that developed periodically in the stomach and duodenum and migrated down into the small intestine. The interdigestive motor activity during fasting was replaced by a digestive pattern after feeding, which consisted of continuous low amplitude contractions. Partial obstruction of the small bowel was initiated during a quiescent period between two IMCs in the fasting state. The first effects were observed on the motility patterns in the stomach and duodenum following the first meal after creation of the obstruction. The IMCs, which would normally be observed 13-15 hours after eating, were suppressed completely, with prolongation of the digestive pattern into the postprandial period. The abolishment and its replacement by the digestive pattern had been persisted until the obstruction was released in 2 or 3 weeks. Similar changes in the motility pattern were observed in the small intestine, however the transformation required much longer period of time than in the stomach and duodenum. The change was first seen in the intestinal segment just proximal to the site of occlusion at 2 weeks after obstruction, and extended proximally to involve whole of the small intestine proximal to the obstruction by 3 weeks. Vomiting and retching were most frequently observed in this stage in association with the retrograde giant contractions. Single series of IMCs often reappeared transiently after vomiting a large volume. After release of the occlusion, recovery of motility started with the reappearance of IMCs, first in the small intestine, followed by the stomach and duodenum. Earlier release (2 weeks) allowed an earlier recovery than later release (3 weeks). The disappearance of the interdigestive pattern and prolongation of the digestive pattern were the primary changes in gastrointestinal motility associated with chronic ileus. The prompt cessation of gastroduodenal IMCs in response to an obstruction down-stream in the small bowel was thought to be a kind of defense reaction mediated through neurohumoral mechanisms to prevent intestinal stagnation. The persistence of the intestinal IMCs, on the other hand, was similarly thought to be an attempt to clear intestinal stagnation despite the obstruction. These experimental data reaffirm the importance of early gastrointestinal decompression and early release of obstruction in clinical practice.
日本平滑筋学会の論文
2002-08-27

慢性小腸イレウス時の消化管運動変化に関する実験的検討

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