Surface Microdialysis for Detection of Colorectal Anastomosis Ischemia-An Experimental Study

Inadequate blood supply is one of the major risk factors for anastomotic leak after low anterior rectal resection. Early detection of ischemia might predict complicated healing and enable anastomotic salvage, which is associated with better outcomes. A microdialysis offers a real-time evaluation of adequate bowel perfusion through monitoring of tissue metabolism. In this experimental study, we assessed the role of microdialysis in detecting early ischemia after colorectal anastomosis.

Colorectal anastomosis was performed in six miniature pigs. A microdialysis catheter was placed on the bowel serosa 5 mm proximal to the anastomosis. Metabolic changes were monitored hourly before and after initiating ischemia, which was induced by ligation of the inferior mesenteric artery and skeletonization of the mesocolon.

Significant increase in tissue levels of lactate was detected after 60 min of ischemia (13.6 [10.4-16.1] versus 6.75 [1.8-9.6] mmol/L at baseline; P < 0.005). The lactate/pyruvate ratio increased accordingly. The concentration of glycerol increased significantly after 2 hours-from a baseline value of 29.5 (3-84) to 125 (79-201) mmol/L (P < 0.005). The decrease in glucose levels was also significant after 60 minutes-0 (0-0.2) versus 4.7 (3.3-6.8) mmol/L at baseline. However, its values started to decline before ischemia.

Surface microdialysis can detect ischemic changes early and may be a promising method in postoperative monitoring of colorectal anastomosis.