INTRAMUCOSAL ACIDOSIS AND SYSTEMIC HOST RESPONSES IN ABDOMINAL AORTIC-ANEURYSM SURGERY

Objectives: To assess the specific host responses to systemic endotoxe mia and tumor necrosis factor (TNF) activation after abdominal aortic aneurysm surgery by measuring antiendotoxin core antibodies (EndoCab) immunoglobulin (Ig)G and IgM, and soluble p55TNF receptor concentratio ns, The role of the gut in initiating these immune responses was evalu ated by correlating the systemic markers to changes in the intramucosa l pH of the sigmoid colon. Design: Retrospective, reevaluation study. Setting: Vascular unit of a university hospital. Patients: Eleven pati ents who underwent abdominal aortic aneurysm repair surgery were selec ted from a larger patient cohort (n = 42) on the basis of their clinic al outcome (four patients had fatal complications and seven patients h ad an uneventful recovery). Interventions: After induction of anesthes ia, intramucosal pH of the sigmoid colon was measured using tonometry, Blood samples were obtained from indwelling catheters or direct venip uncture preoperatively, during surgery, and daily until postoperative day 5. Measurements and Main Results: Those patients who died develope d intramucosal acidosis of the sigmoid colon intraoperatively. Signifi cant consumption of both IgG and IgM EndoCab antibodies was found in a ll patients, By measuring the concentration of antibodies to a neutral antigen, i.e., tetanus toxoid, the consumption of IgG EndoCab antibod y concentrations was shown to be a specific host response, In all pati ents, reciprocal changes in the serum concentrations of p55TNF recepto r and interleukin (IL)-6 were observed, The percentage increase in p55 TNF receptor and the concentration of IL-6 were significantly higher i n the nonsurvivor group by 48 hrs. There were significant correlations between, intramucosal pH and EndoCab antibodies, intramucosal pH and p55 TNF receptor, and p55 TNF receptor and IL-6. Conclusions: The deve lopment of colonic ischemia is associated with a significant consumpti on of IgG EndoCab antibodies and a simultaneous increase in soluble p5 5TNF receptor, This study provides further support for the concept tha t gut-derived endotoxin and the generation of TNF may play a role in t he pathogenesis of complications after abdominal aortic aneurysm surge ry.