Intraoperative Ischemia of the Distal End of Colon Anastomoses as Detected With Visible Light Spectroscopy Causes Reduction of Anastomotic Strength

BackgroundTo explore new methods for intraoperative evaluation of tissue oxygenation, we evaluated the use of visible light spectroscopy as a predictor of anastomotic strength in an experimental model with ischemic murine colon anastomoses.Materials and methodsMale rats (n = 34) were divided into 2 groups (ischemia and nonischemia). In the ischemia group the arteries of the distal colon were ligated until tissue oxygen saturation (StO2) dropped below 55%. A segment of the proximal part of the colon was resected until a well-perfused area was reached and an anastomosis was performed. In the nonischemia group, resection of a segment of descending colon and a colon anastomosis was performed. The animals were sacrificed on the 3rd or 7th postoperative d. The anastomosis was tested for bursting pressure and breaking strength.ResultsAfter ligation of the relevant mesenteric arteries, StO2 of the distal part of the colon decreased (54.6% SD 6.4% versus 71.2% SD 7.4%, P ≤ 0.05). On the 3rd or 7th postoperative d StO2 had normalized. Adhesion score in the ischemia group was higher compared to the nonischemia group (1.6 versus 0.4, P ≤ 0.05). There were no differences in bursting pressure between both groups. Breaking strength was lower in the ischemia group on the 3rd postoperative d (162.3 SD 47.3 versus 212.6 SD 41.2, P ≤ 0.05).ConclusionIschemia can intraoperatively accurately be detected by visible light spectroscopy. Partially ischemic anastomoses showed more adhesions and diminished breaking strength in the early phase of healing, whereas bursting pressure was not affected. Low StO2 of a distal colon anastomosis appeared to be a risk factor for anastomotic dehiscence at d 3 and beyond.