Inferior mesenteric venous sampling, pulse oximetry, and assessment of colonic perfusion during aortic aneurysm surgery

Ischemic colitis is a serious complication of aortic surgery. The condition continues to be difficult to diagnose at an early stage. This study monito rs the biochemical changes in systemic and selective inferior mesenteric ve in (IMV) blood sampling during aortic surgery and compares the reproducibil ity of this method to intraoperative colonic pulse oximetry in a series of 18 patients undergoing infrarenal aortic aneurysm repair. Base excess, pH, pCO(2), and lactate were altered by aortic cross-clamping but returned to n ormal within 48 hr. IMV inorganic phosphate levels were higher than systemi c values, suggesting improved sensitivity with selective sampling. BE isoen zymes of creatine kinase remained normal in all patients. Pulse oximetry si gnals were inconsistently obtained from the colon. This study establishes t he physiological changes in IMV biochemistry during aortic surgery. Unlike intraoperative pulse oximetry, selective IMV sampling provides reproducible measurements of colonic perfusion. This simple and safe technique warrants further assessment of its accuracy at diagnosing ischemic colitis.