The effect of chronic progressive distal large bowel obstruction on intestinal blood flow was studied in 12 mini-pigs. Blood flow was measured by the techniques of xenon133 clearance and intracardiac injections of radiolabelled microspheres. Intestinal blood flow was increased in the left colon and ileum but decreased in the caecum. Blood was shunted from the mucosa to the muscle layers. The results suggest that primary anastomosis of the obstructed left colon is not contraindicated by haemodynamic considerations.

The effect of chronic progressive distal large bowel obstruction on colonic motility was studied in six mini-pigs. Motility was detected in vivo during the development of obstruction with chronically implanted Ag/AgCl electrodes using an impedance technique. When the obstruction was complete the segments of bowel were resected and spontaneous contractile activity and response to cholinergic stimulation were studied in an organ bath. Any hypermotility resulting from obstruction was shortlived and a gradual state of hypomotility supervened proximal to the obstruction. Decompression of the bowel did not result in the immediate return of motility and the resected bowel was unresponsive to carbachol. These results suggest that spontaneous resolution of large bowel obstruction is unlikely and that motility disturbances are unlikely to be a cause of anastomotic dehiscence.

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