Selective decontamination of the digestive tract in cardiac surgical patients.

Objective: To test the hypothesis that selective decontamination of the digestive tract improves outcome in cardiac surgical patients.

Design: Prospective, consecutive, controlled trial over two 4-month periods.

Setting: Eight-bed, open-plan postcardiac surgery ICU.

Patients: All patients undergoing cardiac bypass surgery were eligible. Patients requiring endotracheal intubation for greater than 4 days were included in the analysis. In the initial 4 months, 12 (8.5%) of 141 patients required greater than 4 days of intubation. These 12 patients were not treated with selective decontamination of the digestive tract. We therefore used these patients as the control group. In the second 4-month period, 12 (6.6%) of 180 patients were treated with selective decontamination of the digestive tract and formed the study group.

Main Outcome Measures: The primary measure was mortality. Secondary measures included oropharyngeal decontamination and the presence of lower airway infection.

Interventions: Cephradine prophylaxis. The study group received every 6 hrs 4 mL orally and 20 mL intragastrically a suspension of antimicrobial agents (tobramycin 80 mg, polymyxin E 100 mg, amphotericin B 500 mg), starting on postoperative day 1. The control group did not receive any oral antimicrobial agents.

Results: Mortality rate was significantly (p less than .05) reduced from eight (66%) of 12 patients in the control group to two (16.7%) of 12 patients in the selective decontamination of the digestive tract group. No differences in oropharyngeal decontamination or lower airway infection rates between the two groups were found.

Conclusions: There is a reduced mortality rate in patients receiving selective decontamination of the digestive tract. However, the reader should recognize the small sample size studied. A simple suspension of the antimicrobial agents failed to rid the oropharynx of bacteria.