Effect of dexmedetomidine on intestinal mucosal injury in patients undergoing cardiac valve replacement with CPB

Objective To evaluate the effect of dexmedetomidine on the intestinal mucosal injury in the patients undergoing cardiac valve replacement with cardiopulmonary bypass (CPB). Methods Forty patients of both sexes with rheumatic heart disease, aged 32-64 yr, weighing 40-75 kg, of ASA physical status Ⅱ or Ⅲ(NYHA class Ⅱ or Ⅲ), scheduled for elective cardiac valve replacement with CPB, were randomly divided into 2 groups (n=20 each) using a random number table: control group (group C) and dexmedetomidine group (group D). After induction of anesthesia, the patients were endotracheally intubated and mechanically ventilated. Anesthesia was maintained with 0.8%-2.0% sevoflurane inhalation and intermittent iv boluses of sufentanil 0.5-1.0 μg/kg and vecuronium 0.04-0.06 mg/kg. Before routine induction of anesthesia, a loading dose of dexmedetomidine 1 μg/kg was injected intravenously over 10 min, followed by continuous infusion at 0.3 μg·kg-1·h-1 until the end of surgery in group D, while the equal volume of normal saline was given in group C. Before CPB, at 30 min after aortic clamping, at the termination of CPB, at the end of surgery and at 6 and 24 h after surgery, central venous blood samples were taken for determination of concentrations of tumor necrosis factor-alpha, interleukin-6(IL-6) and IL-10 and intestinal fatty acid binding protein in plasma (by ELISA), and the plasma concentration of endotoxin (using turbidimetry). The time of postoperative mechanical ventilation and duration of ICU stay were recorded. Results Compared with group C, the concentrations of tumor necrosis factor-alpha, IL-6, IL-10 and endotoxin and intestinal fatty acid binding protein in plasma were significantly decreased, and the time of postoperative mechanical ventilation and duration of ICU stay were shortened in group D. Conclusion Dexmedetomidine infused continuously at 0.3 μg·kg-1·h-1(until the end of surgery) after a loading dose of 1 μg/kg before routine induction of anesthesia can reduce intestinal mucosal injury in the patients undergoing cardiac valve replacement with CPB. Key words: Dexmedetomidine; Cardiopulmonary bypass; Intestinal mucosa; Heart valve prosthesis implantation