Endogenous endotoxemia of intestinal origin during cardiopulmonary bypass. Role of type of flow and protective effect of selective digestive decontamination.

OBJECTIVE: To evaluate the possible related factors to endotoxemia and cytokine activation during the ischemic phase of extracorporeal surgery, and the effect of selective digestive decontamination (SDD) as a preventive measure. DESIGN: Prospective, open, randomized trial. SETTING: Two multidisciplinary ICUs (tertiary care hospitals). PATIENTS: One hundred consecutive patients undergoing cardiopulmonary bypass (CPB), randomly allocated to two groups; gut decontamination (group I = 50 cases) and controls (group II = 50 cases). INTERVENTIONS: Preoperative administration of oral non-absorbable antibiotics (polymyxin E, tobramycin and amphotericin B) versus no administration. MEASUREMENTS AND RESULTS: The assessment of decontamination by means of the bacteriologic control of rectal swabs. Determinations of gastric intramucosal pH (gastric pHi) and plasma endotoxin, tumor necrosis factor (TNF) aNd interleukin-6 (IL-6) before surgery and during the ischemic and reperfusion phases of bypass. Rectal aerobic Gram-negative bacilli (AGNB) were significantly reduced in the treated patients and in 56% total eradication was achieved. Endotoxin, TNF and IL-6 plasma levels were significantly lower in this group. By contrast, both endotoxin and TNF/IL-6 levels and gastric pHi correlated with the type of surgical flow (pulsatile versus non-pulsatile). CONCLUSIONS: SDD reduces the gut content of enterobacteria. This may explain the lower endotoxin and cytokine levels detected in decontaminated patients. In addition to SDD, the type of flow employed during bypass seems to influence endotoxemia and cytokine levels.