Interleukin-6 (IL-6) is a major marker of tissue injury. Surgery induces a systemic
IL-6 response related to the magnitude of the operation. An exaggerated
IL-6 response is associated with the development of major complications after
aortic aneurysm repair.
Endotoxemia is a potent stimulus for
cytokine release and may occur during aortic surgery. This study attempted to examine whether the observed
IL-6 response during abdominal aortic surgery is related to the development of portal
endotoxemia. Serial samples of inferior mesenteric and systemic venous blood were obtained before, during, and after aortic cross-clamping in eight patients undergoing elective
aortic aneurysm surgery. Portal
endotoxemia was detected in only five of the eight patients during the surgery, and there was no correlation with the
IL-6 response. Both portal and systemic
IL-6 levels rose during the course of surgery, but, by the time of
abdominal wound closure, the mean portal
IL-6 levels were eight times higher than the systemic
IL-6 levels. These results suggest that the portal circulation draining the colon is a major source of the previously observed systemic
IL-6 response to aortic surgery. The
IL-6 response is not clearly related to portal
endotoxemia but may reflect occult cellular injury in the colon occurring during surgery.