Ischaemic colitis in the experimental animal. II. Role of hypovolaemia in the production of the disease.

Hypovolaemia alone did not lead to ischaemic colitis but when venesection was induced immediately after the acute ligation of the common colic artery large bowel ischaemia ensued. Similarly, hypovolaemia induced one month after two major blood vessels had been occluded led to ischaemic colitis. These findings suggest that states of low blood flow in the presence of previous arterial constriction or blockage may lead to enough reduction in mesenteric perfusion for intestinal ischaemia to develop. Using an electromagnetic flowmeter placed in the cranial mesenteric artery of the dog, it was shown that hypovolaemia may lead to 50-75% reduction in mesenteric blood flow without producing any significant change in the systemic blood pressure.