Transient profound mesenteric ischemia strongly affects the strength of intestinal anastomoses in the rat.

PURPOSE: Experimental data suggest that transient preoperative ischemia and reperfusion may compromise anastomotic strength. However, data on this subject are equivocal, in particular as to the onset and duration of this effect. This study was designed to comprehensively characterize the effects of profound transient intestinal ischemia on anastomotic healing during the first postoperative week.
METHODS: Ischemia was induced in rats by clamping both the superior mesenteric artery and ileal branches for 30 minutes. Immediately after declamping, anastomoses were constructed in both terminal ileum and descending colon. After three, five, or seven days, both bursting pressure and breaking strength were measured. Anastomotic collagen content, gelatinase activity, and histology were analyzed.
RESULTS: Anastomotic leakage rate was 13 percent in ischemia-reperfusion group and 0 percent (P=0.02) in controls. The breaking strength in ileum remained significantly (P<0.05) lower in the ischemic groups than in the control groups at all time points. Bursting pressure in the ileum was not significantly different between ischemic and control groups at either of the time points measured. However, at Day 7 the bursting site was significantly more frequent within the suture line in the ischemic groups. In the colon, at Day 3 the bursting pressure was 35 percent lower in the ischemic group than in the control group (P<0.05). Anastomotic collagen content and gelatinase activity were similar in ischemic and control groups.
CONCLUSIONS: Transient profound splanchnic ischemia compromises anastomotic strength throughout the entire first postoperative week. This effect does not seem to be caused by impaired accumulation of wound collagen.