Effect of collateral circulation on healing of small intestinal anastomosis in rabbits

In patients who have acute superior mesenteric artery occlusion and clearly gangrenous intestines, resection and anastomosis have been advised as the only surgical procedure. Distal and proximal bowel segments adjacent to this necrotic part have collateral blood supply although they have normal macroscopic appearance. After resection of necrotic segment, there will be a low flow at the anastomosis due to collateral circulation and the healing may therefore be impaired.

This situation was investigated in rabbits creating unilateral collateral circulation at the small bowel anastomosis. Bursting pressure, tissue hydroxyproline concentration and bursting sites were determined on days 4, 8, and 12. Findings were compared with the those of normal anastomosis.

There was significantly decreased mean bursting pressure(106 +/- 40.3 mmHg) in unilateral collateral circulation group as compared with the that of control group (158 +/- 26.6 mmHg) on day 8 (p < 0.05). On the same day mean hydroxyproline concentration of this group was also lower(7.06 +/- 0.5 mg/g tissue) than the value of control group(7.69 +/- 0.4 mg/g tissue), with the statistical significance on the border line(p = 0.05). The low values of these two parameters reached normal levels on day 12. Bursting sites were mostly on the anastomotic line in unilateral collateral circulation group, while they were mostly on the bowel wall in the control group on day 8.

These findings suggest an insufficient healing process in the bowel anastomosis with unilateral collateral circulation on day 8 in rabbits.