The effect of polycythemia and hyperviscosity on bowel ischemia.

Recent clinical reports suggest that newborn infants with polycythemia and other causes of hyperviscosity may be at risk for developing necrotizing enterocolitis (NEC). This study evaluates the relationship of polycythemia and increased blood viscosity on survival and bowel integrity and an ischemic bowel model in rats. Ninety-nine weanling Sprague Dawley rats underwent one-minute occlusion of the superior mesenteric artery. Animals were divided into five treatment groups. Group 1 (n = 40) ischemic controls had a mean hematocrit (HCT) of 44.3 +/- 3.3%. Group 2 (n = 19) rats were transfused with whole blood from donor rats followed by a dose of lasix (2mg/kg) intravenously (IV) 20 hours prior to ischemic injury, raising the HCT to 53.6 +/- 3.2%. Group 3 (n = 19) animals were transfused with whole blood X 2 and given lasix at 20 and 4 hours before operation, raising the HCT to 63.0 +/- 1.6%. Group 4 (n = 16) (HCT 68.6 +/- 2.55%) and group 5 (n = 15) rats (HCT 71.6 +/- 2.07%) were prepared with multiple blood transfusions and given lasix as group 3 animals to achieve those hematocrit levels. Animals were kept in individual cages and fed rat chow and water ad libitum. Survival, length of survival, and evidence of bowel perforation or necrosis were recorded at seven days following the ischemic insult. Blood viscosity was determined in each group. Survival at one week was 65% in group 1, 63% in group 2, and 63% in group 3.(ABSTRACT TRUNCATED AT 250 WORDS)