Can selective digestive decontamination avoid the endotoxemia and cytokine activation promoted by cardiopulmonary bypass?

OBJECTIVE

To evaluate the effect of selective digestive decontamination on endotoxemia and cytokine activation during the ischemic phase of cardiopulmonary bypass surgery.

DESIGN

Prospective, open, randomized, controlled trial.

SETTING

Two multidisciplinary intensive care units in tertiary care hospitals.

PATIENTS

Eighty consecutive patients randomly allocated to two groups: selective digestive decontamination (group 1, n = 40) and controls (group 2, n = 40).

INTERVENTIONS

Preoperative 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 with circulating endotoxin, tumor necrosis factor and interleukin-6 (IL-6) determinations before surgery, during ischemic and reperfusion phases of bypass, and at 4 hrs and at 24 hrs after surgery. Group 1 patients showed that rectal bacteria decreased ten-fold after treatment for 24 hrs, thousand-fold after 48 hrs, and registered 0 cfu/mL after digestive decontamination was administered for > 72 hrs. Endotoxin and IL-6 assays showed significantly lower values in this latter group vs. those circulating concentrations of control patients. On the other hand, both endotoxin and IL-6 concentrations correlated positively with the duration of surgical ischemia.

CONCLUSIONS

Selective digestive decontamination reduces the gut content of enterobacteria, with complete elimination after 3 days of treatment. This fact could explain the lower endotoxin and cytokine concentrations found in the blood samples of patients who had been fully decontaminated. Duration of aortic cross-clamping is an important factor in generating endotoxemia and in the activation of cytokines.