CAN SELECTIVE DIGESTIVE DECONTAMINATION AVOID THE ENDOTOXEMIA AND CYTOKINE ACTIVATION PROMOTED BY CARDIOPULMONARY BYPASS

Objective. To evaluate the effect of selective digestive decontaminati on on endotoxemia and cytokine activation during the ischemic phase of cardiopulmonary bypass surgery. Design: Prospective, open, randomized , controlled trial. Setting. Two multidisciplinary intensive care unit s in tertiary care hospitals. Patients: Eighty consecutive patients ra ndomly allocated to two groups: selective digestive decontamination (g roup 1, n = 40) and controls (group 2, n = 40). Interventions: Preoper ative administration of oral antibiotics (polymyxin E, tobramycin, and amphotericin B) vs. untreated controls. Measurements and Main Results : Assessment of decontamination by bacteriologic evaluation of rectal swabs (colony-forming units [cfu]/mL) were made in each group, along w ith circulating endotoxin, tumor necrosis factor and interleukin-6 (IL -6) determinations before surgery, during ischemic and reperfusion pha ses of bypass, and at 4 hrs and at 24 hrs after surgery. Group 1 patie nts showed that rectal bacteria decreased ten-fold after treatment for 24 hrs, thousand-fold after 48 hrs, and registered 0 cfu/mL after dig estive decontamination was administered for > 72 hrs. Endotoxin and IL -6 assays showed significantly lower values in this latter group vs. t hose circulating concentrations of control patients. On the other hand , both endotoxin and IL-6 concentrations correlated positively with th e duration of surgical ischemia. Conclusions: Selective digestive deco ntamination reduces the gut content of enterobacteria, with complete e limination after 3 days of treatment. This fact could explain the lowe r endotoxin and cytokine concentrations found in the blood samples of patients who had been fully decontaminated. Duration of aortic cross-c lamping is an important factor in generating endotoxemia and in the ac tivation of cytokines.