Abstracts
2000 Digestive Disease Week

# 2263 Prediction of Anastomotic Complications Following Oesophageal Resection Using Automated Measurement of Gastroplasty Carbon Dioxide GAP.
Peter C. Roberts, Angela McLuckie, William J. Owen, Richard J Beale, Robert C Mason, London, United Kingdom

Background: Gastric mucosal perfusion can be assessed tonometrically by measuring the intra-mucosal pH (pHi) and CO2 gap (tonometer pCO2-arterial pCO2) and its ability to predict outcome following surgery has been demonstrated in previous studies. This study employed automated gas tonometry to measure gastric CO2 gap and pHi following oesophagectomy to test the predictive ability of the technique for anastomotic complications. Method: Gastric tonometers were placed in the gastric tubes of 30 consecutive patients undergoing oesophageal resection and pro-peristaltic tubular gastroplasty. These were connected to a Tonocap analyser (Datex- Engstrom Division, Instrumentarium Corporation, Helsinki, Finland). The gastric CO2 gap and pHi were calculated at 12 hourly intervals up to 48 hours post-operatively. Results: 11 patients suffered an anastomotic leak or benign stricture. Because of balloon failure or re-operation within 48 hours of surgery data was not available for 1 patient from each of the complication and no complication groups. Mean (s.d.) CO2 gap and pHi over the first 48 post-operative hours were 1.7 kPa (0.8) and 7.26 (0.06) in the no complication group and 3.5 kPa (2.0) and 7.18 (0.11) in the complication group respectively. The difference in CO2 gap between the 2 groups was more significant than in pHi (p<0.005 and p<0.05). and the CO2 gap was a better predictor of outcome than the pHi, with areas under their respective ROC curves of 0.847 and 0.684. A mean CO2 gap of 2.5kPa or above had a sensitivity of 80% , a specificity of 82% and a likelihood ratio of 4.0 for predicting anastomotic complications. Conclusions: Gastric tube CO2 gap and pHi are easily measured using recirculating gas tonometry. Mean CO2 gap was higher and pHi lower over the first 48 hours following surgery in those patients in whom an anastomotic complication subsequently developed than in those in whom it did not. The CO2 gap proved to be a better predictor of complications than the pHi. These findings suggest that the CO2 gap may useful as a therapeutic goal if used in conjunction with measures to improve gastric tube CO2 gap post-operatively and that this might reduce the incidence of anastomotic failure.