Enteral feeding causes an increase of intestinal oxygen demand depending on the amount administered. The aim of this study presented was to evaluate, whether intraoperative duodenal feeding might put patients at risk developing splanchnic O(2)-imbalance due to an intraoperatively compromised intestinal perfusion based on stress and unrecognized hypovolemia. In 18 severely burned patients, the CO(2)-gap between the arterial and gastric CO(2), as a parameter for the intestinal O(2)-balance, was measured during the first operation. All operations were performed on day 3-5 after admission and lasted for 4-5h. Half of the patients (nine patients) were fed intraoperatively, whereas in the other nine patients feeding was suspended beginning 1h prior to surgery until 6h after surgery. CO(2)-gap measurements were carried out prior to surgery, hourly during the operation and 5h postoperatively. Measurements 3 and 4h after beginning of the operation revealed significantly higher CO(2)-gap values in the fasting group. All other measurements showed no significant difference between both groups. Therefore, intraoperative enteral nutrition, at least in the early postburn phase, is not only necessary for reducing caloric deficits, but also seems to have a protective effect on gut oxygen balance.