Intraoperative assessment of colonic perfusion using scanning laser Doppler flowmetry during colonic resection

Background: Ischemia occurring on mobilization and mesenteric division is t hought to be a major factor in the etiology of anastomotic dehiscence after colorectal resection. This study assessed the ability of the new technique of scanning laser Doppler flowmetry to measure changes in human colonic pe rfusion during mobilization at and adjacent to the anastomotic site. Study Design: Colonic perfusion was measured in 10 patients undergoing larg e-bowel resection by making laser Doppler scans of the proximal bowel befor e mobilization, after mobilization and mesenteric division, and after resec tion of the specimen. Mean perfusion was calculated within 1-cm(2) regions of interest, each of which contained 1,750 individual measurements of perfu sion. These regions represented the anastomosis site and adjacent areas 1 c m and 2 cm proximal and distal to this. The results were expressed as mean perfusion units (PUs). Results: After mobilization, there were significant decreases in perfusion in all the subjects between each time point and in all areas of the colon s canned. Median perfusion at the anastomosis site was 491 PUs before mobiliz ation, and this fell to 212 PUs after mobilization, representing a decrease of 57%; the median within-person decrease was also 57% (p < 0.01). There w as a gradient of reduced perfusion between the area 2 cm proximal to the me senteric division (median within-person fall 25%; p < 0.05) and the area 2 cm distal to the mesenteric division (median within-person fall 84%; p < 0. 01). After resection of the specimen, perfusion increased slightly at the a nastomosis site to a median of 240 PUs (median within-person fall 41%; p < 0.01), but 2 cm proximal to this, median perfusion remained depressed at 33 0 PUs. Conclusions: This new technique can be used intraoperatively and appears to overcome the limitations of single-point laser Doppler flowmetry. In this small preliminary study, it measured large decreases in colonic perfusion d uring mobilization, and it may have widespread clinical applications. (J Am Coll Surg 2000; 191:506-510. (C) 2000 by the American College of Surgeons) .