The Protective Effects Of Remifentanil Preconditioning On Cerebral Injury During Pump-assisted Beating Heart CABG

Objectives: To investigate the protective effects of remifentanil preconditioning on cerebral injury during pump-assisted beating heart coronary artery bypass grafting and to analysis the dose related effects of remifentanil and its mechanisms.Methods: 40 consecutive patients ( ASAⅡ～Ⅲ) aged 48-76 yr undergoing elective pump-assisted beating heart coronary artery bypass grafting were randomized into two groups: those receiving remifentanil preconditioning (group R) and those not receiving it (group C).There were three subgroups of 10 patients each according to different doses of remifentanil in group R: R1 (remifentanil 0.6μg/kg·min),R2(remifentanil 1.2μg/kg·min),R3(remifentanil 1.8μg/kg·min). All patients were injected with scopolamine hydro -bromide 0.3mg at the time 1h before operation. Arteria radialis and internal jugular vein pricking were performed with local anesthesia. Anesthesia was induced by remifentanil 1μg/kg, propofol 1mg/kg. Pipecuronium bromide 0.1mg/kg was administered to facilitate endotracheal intubation . Propofol, isoflurane, sufentanil and pipecuronium bromide were used during the maintenance of anesthesia for all patients. PETCO2 was kept at 35~45mmHg by mechanical ventilation. During 30 minutes after anesthesia induction patients received either pretreatment with remifentanil (remifentanil preconditioning, 5-min infusion,5-min resting×3) using 0.6,1.2,or 1.8μg/kg·min intravenously or preconditioning by 0.9%Sodium Chloride, performed with the same regime (3×5-min infusions). Levels of S-100βprotein ,SOD and MDA were evaluated in jugular bulb blood samples drawn before induction of anesthesia (T0), before CPB (T1), 30min after the initiation of CPB (T2),and at the end of CPB (T3). The neuropsychological tests, Mini-Mental State Examination (MMSE), was administered 24h prior to surgery and on 24th postoperative hours. SPSS10.0 software was used for statistical analyses. Normally distributed data were expressed as mean±standard and compared with 1-way analysis of variance.and Student-New-Keuls test. Linear regression analysis was performed to evaluate the value of S-100βlevel and both SOD and MDA.Results: There were no differences in scores of MMSE evaluated 24h before and after CABG among these four groups, but the difference of MMSE scores between 24h before and after operation at group R3 showed a statistically significant decline in the total performance. No significant differences of S-100β,SOD and MDA levels were found among these four groups before operation and all the markers were normal. A Significant increase in the median serum levels of S-100βand MDA were observed at T1-T3 (p<0.05) and at T2-T3(p<0.01) was noticeable, while SOD levels at T1-T3(p<0.05) were lower than T0 and at T2-T3(p<0.01)more obviously in all groups. In patients with groupR3 outcomes, S-100βand MDA levels were significantly higher than those in patients with other group outcome at T2-T3(p<0.05)and SOD was contradictory. Linear regression analysis revealed a significant relation between S-100βand MDA level at 30 minute of CPB(r=0.71,p< 0.01) and at the end of CPB(r=0.71,p<0.01). Furthermore, there is also a significant relation between S-100β(r=-0.762,p<0.01) level and SOD at 30 minute of CPB and at the end of CPB(r=-0.795,p<0.01).Conclusion:1.Remifentanil preconditioning with group high concentration can protects against brain injury. 2.Inhibitting oxidative stress reaction may be contribute to neuroprotection of remifentanil preconditioning.