Interleukin 6 production during abdominal aortic aneurysm repair arises from the gastrointestinal tract and not the legs

BACKGROUND: Abdominal aortic aneurysm (AAA) repair is associated with a systemic inflammatory response. This inflammatory response probably arises as a result of an ischaemia-reperfusion injury to the legs and gastrointestinal tract. In this study the relative contributions of these areas to the inflammatory response were assessed during elective AAA repair. METHODS: Blood was sampled from the femoral vein, portal vein and radial artery of 14 patients undergoing elective AAA repair at five time points during the procedure. Plasma was snap-frozen for subsequent batch analysis of interleukin (IL) 6. RESULTS: The plasma IL-6 concentration rose steadily throughout the procedure at all three locations. The increase in plasma IL-6 was significantly greater in the portal vein than in the radial artery during ischaemia (P = 0.020). The plasma IL-6 concentration was also significantly higher in the portal vein than in the femoral vein (P < 0.001) and radial artery (P < 0.001) during reperfusion. There were no significant differences between radial artery and femoral vein IL-6 levels at any time point. CONCLUSION: Ischaemia and reperfusion during AAA repair were associated with a marked increase in IL-6 concentration in the portal vein, suggesting that IL-6 was produced by the gastrointestinal tract.