Cerebral protective effect of remifentanil preconditioning during cardiopulmonary bypass in patients undergoing coronary artery bypass grafting

Objective To investigate the cerebral protective effect of remifentanil preconditioning during cardiopulmonary bypass in patients undergoing coronary artery bypass grafting (CABG). Methods Forty ASA Ⅱ or Ⅲ patients of both sexes aged 55-64 yr weighing 50-85 kg undergoing elective CABG were randomized into 4 groups (n = 10 each) : control group (group C) and remifentanil groups (group R_1, R_2, R_3). Anasthesia was induced with midazolam 0.04 mg/kg, remifentanil 1 μg/kg, propofol 1 mg/kg and pipecuronium 0.1 mg/kg and maintained with isoflurane inhalation,intravenous continuous propofol infusion at 6-10 mg·kg~(-1)·h~(-1) and intermittent iv boluses of sufentanil and pipecurpnium after tracheal intubation. The patients were mechanically ventilated. P_(ET) CO_2 was maintained at 35-45 mm Hg. A catheter was inserted into internal jugular vein and advanced cranially until jugular bulb for blood sampling. The remifentanil groups received three 5 min episodes of iv remifentanil infusion at 0.6 μg/kg~(-1) ·min(-1) (group R_1),1.2μg/kg~(-1) ·min(-1)(group R_2) and 1.8μg/kg~(-1) ·min(-1)(group R_3) at 5 min intervals after induction of anesthesia before operation.Blood samples were obtained from jugular bulb before induction of anesthesia (T_0, baseline), before CPB (T_1), 30 min after initiation of CPB (T_2) and at the end of CPB (T_3) for determination of plasma S-100βprotein and MDA concentrations arid SOD activity. Results Plasma S-100β protein and MDA concentrations were significantly increased while plasma SOD activity was significantly decreased at T as compared with the baseline values at T_0 in all 4 groups. Plasma S-100β protein and MDA concentrations were significantly lower while plasma SOD activity was significantly higher at T_2 and T_3 in group R_3 than in the other 3 groups. Conclusion Preconditioning with larger doses of remifentanil (1.8 μg/kg~(-1) ·min(-1)) can attenuate brain injury induced by CPB in patient undergoing CABG through inhibiting oxidative stress response. Key words: Piperidines;  Brain;  Cardiopulmonary bypass;  Coronary artery bypass