THE EFFECT OF POLYCYTHEMIC HYPERVISCOSITY ON ISCHEMIC BOWEL NECROSIS

It is known that polycythemia decreases the fluidity of the blood and impairs tissue perfusion due to red-cell sludging in the microcirculat ion. In this study, the effect of polycythemic hyperviscosity (PH) on bowel necrosis was evaluated in an experimental model of intestinal is chemia. Twenty-eight Wistar albino rats (90-170 g) were divided into t wo groups: group 1 was transfused to create hyperviscosity and then in testinal ischemia was produced (n = 16); in group 2 ischemia was produ ced without transfusion (n = 12). Intestinal ischemia was produced by clamping the superior mesenteric artery and the collateral arcades of the right colic artery for 30 min. Gross and histopathologic evaluatio ns were performed by either immediate necropsy or relaparotomy 24 h la ter. Microscopic findings were graded from 0 to 3 according to the deg ree of ischemic changes. In group 1, 2 animals (12.5%) died before 24 h postoperatively; coagulation necrosis with grade 2 or 3 ischemic cha nges was observed in 10 animals (62.5%). In group 2 only a few hypertr ophied Peyer's patches and capillary dilation were found, and all hist opathologic changes were between grades 0 and 1. The difference betwee n the histopathologic gradings of the two groups was significant (P <0 .001). It appears that in addition to reduced splanchnic blood flow, a secondary effect of PH is needed to induce ischemic coagulation necro sis, PH of the newborn must be considered a risk factor for necrotizin g enterocolitis, so-called spontaneous intestinal perforations, and ev en intestinal atresia.