Heme compounds in the plasma in small bowel ischemia in the rat

The early diagnosis of acute mesenteric occlusion presents a difficult problem in abdominal surgery. In a study on rats the relation between graded small bowel ischemia and the concentration of heme compounds in the plasma was investigated. The ischemia was produced by ligation of terminal vessels at the mesenteric margin of the intestine (mesenteric end arcades) or the superior mesenteric artery. Heme compounds were assayed by a benzidine method developed by Crossby et al. The concentration of heme compounds in the plasma was higher in animals with various grades of intestinal ischemia than in animals subjected to laparotomy alone. This increase was noted as early as 4 hours after induction of moderate and severe grade of ischemia. The results indicate that an increase in plasma concentration of heme compounds takes place at an early stage of moderate and severe small bowel ischemia following mesenteric vascular occlusion but not until after 48 hours in mild ischemia. The clinical value of this method has to be tested in a clinical study.