Cardiopulmonary bypass in man: role of the intestine in a self-limiting inflammatory response with demonstrable bacterial translocation.

Background: Cardiopulmonary bypass provokes a systemic inflammatory reaction that, in 1% to 2% of all cases, leads to multiorgan disfunction. The aim of this study was to evaluate the possible role of the intestine in the pathogenesis and development of this reaction.

Methods: Eleven selected patients scheduled for elective coronary artery bypass graft surgery were enrolled in a open, prospective clinical study. Gastric tonometry, chromium-labeled test and double sugar intestinal absorption tests, polymerase chain reaction microbial DNA test, and measurement of cytokines and transcriptional factor (nuclear factor kappaB) activation were performed.

Results: During the postoperative period, gastric pH remained stable (range,7.2 to 7.3). The partial pressure for carbon dioxide gradient between the gastric mucosa and arterial blood increased significantly (from 1 to 23 mm Hg), peaking in the sixth postoperative hour. Interleukin 6 increased significantly over basal levels, peaking 3 hours after cardiopulmonary bypass (96.3 versus 24 pg/mL). Nuclear factor kappaB never reached levels higher than those observed after lipopolysaccharide stimulation. Escherichia coli translocation was documented in 10 patients: in eight cases from removal of aortic cross-clamps and in two cases from the first postoperative hour. With respect to basal value (6.4%), the urine collection revealed a significant increase in excretion of the radioisotope during the first 24 hours after surgery (39.1%), although there were no significant variations with the double sugar test.

Conclusions: The results obtained showed a correlation between the damage of the gastrointestinal mucosa, subsequent increased permeability, E coli bacteremia, and the activation of a self-limited inflammatory response in the absence of significant macrocirculatory changes and postoperative complications.