Nonocclusive Intestinal Ischemia

Intestinal ischemia is either occlusive or nonocclusive. Occlusive intestinal ischemia is caused by complete or very high grade obstruction of a major mesenteric artery or one or more of its principal segmental branches, usually by a thrombus (often on a plaque) or an embolus. Nonocclusive intestinal ischemia is associated with low flow states, mesenteric vasoconstriction, and mucosal hypoperfusion without actual obstruction to arterial inflow; it frequently coexists with congestive cardiac failure and generalized arteriosclerotic vascular disease (including arteriosclerosis of mesenteric arteries) but the degree of stenosis in the mesenteric vasculature is insufficient alone to account for the sudden development of this acute and often fatal ischemia. Another useful distinction is that of small intestinal ischemia as opposed to colonic ischemia. Either may be occlusive or nonocclusive. Ischemia of the small intestine is associated with a much poorer prognosis,¹ and may be the event that leads to irreversibility in many