Tonometric measurement of gastric intramucosal pH following oesophagectomy predicts postoperative complications

Background: Gastric mucosal hypoperfusion can be assessed tonometrically by measuring the gastric intramucosal pH (pH i ); its ability to predict outcome in the critically ill has been demonstrated previously. This study employed the new technique of recirculating gas tonometry to measure gastric pH i following oesophagectomy; its ability to predict anastomotic complications was tested, since ischaemia at the oesophagogastric anastomosis is thought to be an important factor in their aetiology. Methods: A gastric tonometer was placed in the gastric tube of 28 consecutive patients undergoing oesophageal resection. They were connected to a Tonacap analyser (Datex‐Engstrom Division, Instrumentarium Corporation, Helsinki, Finland) which automatically samples gas from the intragastric tonometer balloon and measures the carbon dioxide concentration within it. In conjunction with simultaneously taken arterial blood samples, gastric pH i was calculated at the end of the operation and then at 12‐h intervals for up to 48 h after operation. Patients who survived were followed for 3 months and all postoperative complications were recorded. Statistical comparison was made using the independent samples t test. Results: Eight patients suffered an anastomotic leak or benign stricture after operation; five others had a life‐threatening complication not thought to be related to the anastomosis, of whom two survived. Over the first 24 h after operation median gastric pH i was lower at all three measurement points in the complication group than in the no complication group ( P > 0·05 in all cases). However, at 36 and 48 h there were significant differences (in both cases P < 0·01); at these times median (range) pH i in the complication group was 7·19 (7·00–7·24) and 7·20 (7·03–7·49) respectively, and in the no complication group 7·28 (7·12–7·39) and 7·32 (7·25–7·44). A mean pH i at 36 and 48 h after operation of 7·25, with both measurements less than this value as a discriminating coefficient, was employed. This had a sensitivity of 92 per cent and a specificity of 92 per cent for predicting all complications. Applied specifically to anastomotic complications the sensitivity was 100 per cent and specificity 92 per cent. Conclusion: Gastric pH i is easily measured after operation using recirculating gas tonometry. By taking measurements at 36 and 48 h, it appears possible to predict postoperative complications following oesophagectomy and the technique may provide a useful adjunct to the monitoring of these patients. © 1999 British Journal of Surgery Society Ltd