Abstracts
1998 Digestive Disease Week

#976 <Serial.>2793

ASSESSMENT OF COLONIC PERFUSION DURING COLONIC RESECTION USING SCANNING LASER DOPPLER FLOWMETRY. NH Boyle, WJ Owen, AC Pearce and RC Mason. UMDS, Guy's and St. Thomas' Hospitals, London, UK.

Aims Following colonic resection tissue ischaemia is thought to be important in the aetiology of anastomotic leak. Scanning laser Doppler flowmetry is a new non-invasive technique for rapidly assessing tissue blood flow over a large area. Up to 250 individual single point measurements of perfusion per second are made as a laser beam is scanned over a surface and we have assessed this technique to detect changes in colonic perfusion during surgery.

Methods 8 patients undergoing colonic resection for malignancy were studied. Measurements of colonic perfusion in the bowel being mobilised using laser Doppler scans were made prior to colonic mobilisation, after mesenteric division and after resection and preparation of the bowel for anastomosis. From each scan two images were produced and stored electronically. On the photographic images identical regions of interest(ROIs) each of 1.5cms2 were analysed these representing the area of anastomosis, and 1 and 2 centimetres proximal and distal to this site. These equated to a mean of over 1750 individual measurements on the corresponding colour perfusion images and mean perfusion units (PUs) from within each ROI and percentage changes were then calculated.

Results There were significant falls in perfusion measured with the scanning laser Doppler in all the subjects between each time point and in all areas of the colon scanned. Mean perfusion at the anastomosis site was 470 perfusion units (PUs) prior to mobilisation and this fell to 215 PUs after mobilisation representing a mean fall of 54%. There was a gradient of reduced perfusion between the area 2cms proximal to mesenteric division (fall 35% p_0.05) and the area 2cms distal to mesenteric division (mean fall 82% p_0.001). This gradient and a line of demarcation at the site of mesenteric division were clearly represented on the colour perfusion images created by the laser imager. After resection of the specimen perfusion increased slightly at the anastomosis site to a mean of 234 Pus (overall fall 50%) whilst 2cms proximal to this mean perfusion remained depressed at 354PUs, representing 78% of the pre-mobilisation value.

Conclusions This study confirms that scanning laser Doppler flowmetry is suitable for intra-operative use, creates easily interpreted colour images of tissue perfusion and has demonstrated large falls in colonic perfusion at the anastomosis site as well as proximally even after resection of the specimen. Further study is needed to assess if this method can be used to predict ischaemia related anastomotic complications.

Copyright 1996 - 1998, SSAT, Inc. Revised 29 June 1998.