Aims: Diagnosis of bowel ischaemia is difficult because of its non-specific presentations and the lack of simple diagnostic tests. Visible light spectrophotometry (VLS) is a new technique for assessment of bowel tissue oxygenation (SO2). The aim of this study is to explore the use of VLS in assessing bowel SO2 in the basal and ischaemic states and compare it with Laser Doppler flowmetry.
Methods: Nine patients undergoing elective left sided colon resections were included in this study. SO2 values were measured perioperatively with VLS in the serosal and the mucosal layers of the descending colon, sigmoid colon and the rectum on four occasions; at the beginning of the operation (baseline), after mobilisation of the sigmoid, after ligation of the inferior mesenteric artery (IMA) and after complete devascularisation of the sigmoid. The mucosal measurements were done by using catheter probe through a flexible sigmoidoscope. Laser Doppler flow was also measured on all these occasions.
Results: The results showed no significant difference in the baseline SO2 and flux between the different parts of the bowel. There was a significant decrease in the mean mucosal SO2 in the sigmoid after ligation of the IMA and after complete devascularisation. The mean (± sd) mucosal SO2 in the sigmoid decreased from a baseline value of 74% ± 5 to 57% ±12 (P = 0.012) after ligation of the IMA and to 36% ±15 (P = 0.012) after complete devascularisation. The serosal SO2 in the sigmoid decreased from a baseline value of 88% ±8 to 80% ±9 after complete devascularisation. There was significant drop in the laser Doppler flux in the serosal and the mucosal layer of the sigmoid following ligation of the IMA and complete devascularisation but the flux values had high variability.
Conclusion: Mucosal SO2 measurements using VLS can accurately diagnose ischaemic state of the colon and therefore may be a useful investigation in patients with suspected colonic ischaemia. If serosal measurements are required, VLS is not reliable and laser Doppler might be more useful.
Singh DB, Stansby GS, Harrison DK, Bain I. Visible spectrophotometry - The way forward in the diagnosis of bowel ischaemia? International Surgical Congress of the Association of Surgeons of Great Britain and Ireland, Bournemouth International Centre, 14th to 16th May 2008.
Dr. David K. Harrison, Durham Unit, Durham. Tel: +44 (0)191-333-2215.
Regional Medical Physics Department, Freeman Hospital, Newcastle upon Tyne, NE7 7DN, UK.
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