Bacterial translocation as a source of Dacron-graft contamination in experimental aortic operation: the importance of controlling SIRS.

BACKGROUND: Several experimental studies have shown the beneficial effects of nitric oxide (NO) in the modulation of the systemic inflammatory response syndrome (SIRS). Nitric oxide is involved in and affects almost all stages in the development of inflammation. We have attempted to ascertain whether the nitric oxide donor molsidomine prevents aortic graft contamination through control of the SIRS and a decrease in bacterial translocation (BT).
METHODS: Twenty-four mini-pigs were divided into 4 groups. The animals were subjected to suprarenal aortic/iliac cross-clamping (for 30 minutes) and by-pass with a Dacron-collagen prosthetic graft impregnated in rifampicin. Groups: 1) sham (aortic dissection alone); 2) cross-clamping and bypass; 3) hemorrhage of 40% of total blood volume before cross-clamping and by-pass; and 4) the same as in group 3 but also including the administration of the NO donor molsidomine (4 mg/kg) 5 minutes before cross-clamping. VARIABLES: 1) bacteriology of mesenteric lymph nodes (MLN), kidney, blood, and prosthesis; 2) serum TNF-alpha (ELISA); and 3) iNOS expression in kidney and liver (Western blot).
RESULTS: Aortic cross-clamping with or without hemorrhage was associated with BT in 80% and 100% of the animals, respectively. About 86% of the bacteria isolated in the graft were also present in MLN. This contamination coincided with an increase in TNF-alpha and with a greater expression of iNOS. Molsidomine administration decreased TNF-alpha and iNOS, decreased BT (from 100% to 20% of the animals), and decreased graft contamination (from 83% to 20%).
CONCLUSIONS: The present model induces high levels of BT and SIRS, both acted as sources of contamination for the implanted Dacron graft. Molsidomine administration decreased the presence of bacteria in the graft by controlling BT and modulating SIRS.