ENDOTOXEMIA, THE GENERATION OF THE CYTOKINES AND THEIR RELATIONSHIP TO INTRAMUCOSAL ACIDOSIS OF THE SIGMOID COLON IN ELECTIVE ABDOMINAL AORTIC-ANEURYSM REPAIR

Ischaemia of the large bowel occasionally occurs following abdominal aortic aneurysm repair and may lead to multiple system organ failure (MSOF). Intramucosal acidosis of the sigmoid colon is a good indicator of sigmoid colonic ischaemia. Intramucosal pH of the sigmoid colon was measured using the silicone tonometer in 21 patients undergoing abdominal aortic aneurysmectomy. Samples were taken for plasma endotoxin, tumour necrosis factor (TNF) and interleukin-6 (IL-6) measurements preoperatively, half-hourly during the operation, 2-hourly for the next 12h, 4-hourly for a further 48 h and 8-hourly thereafter until the fifth day. The intramucosal pH of the sigmoid colon fell to less than 7.00 peri-operatively in 10 patients, four of whom developed diarrhoea; in comparison, this did not occur in any of the 11 whose pH remained greater than 7.00 (p = 0.036). Higher peak concentrations of endotoxin, TNF and IL-6 were found in those patients whose intramucosal pH fell to less than 7.00 compared to those whose pH remained greater than 7.00 (mean ± S.E.M. pg/ml, endotoxin = 112 ± 24 vs. 58 ± 6, p < 0.05; TNF = 26 ± 8 vs. 7 ± 2, p < 0.05; IL-6 = 213 ± 59 vs. 87 ± 12, p = 0.09). In the two patients who died, both from the group with pH level less than 7.00, concentrations of IL-6 were considerably higher than that in most of the other patients. Peri-operative intramucosal acidosis of the sigmoid colon in patients undergoing abdominal aortic aneurysm surgery is associated with higher post-operative concentrations of endotoxin, TNF and IL-6. Therefore, peri-operative intramucosal acidosis of the sigmoid colon may be a useful predictor of a patient's susceptibility to MSOF. © 1993 Grune & Stratton Ltd.