不同麻醉下冠状动脉旁路移植术患者体外循环时脑内氨基酸水平的比较

目的 比较不同麻醉下冠状动脉旁路移植术患者体外循环(CPB)时脑内兴奋性氨基酸及抑制性氨基酸的水平.方法 择期CPB下冠状动脉旁路移植术患者80例,ASA Ⅱ或Ⅲ级,随机分为2组(n=40):异丙酚复合麻醉组(P组)和七氟烷复合麻醉组(S组).麻醉诱导后气管插管,机械通气.麻醉维持:P组气管插管后靶控输注异丙酚,血浆靶浓度1～2 μg/ml,静脉输注瑞芬太尼0.2～0.4 μg·kg-1·min-1,间断静脉注射维库溴铵0.15 mg/kg;S组静脉输注瑞芬太尼0.2-0.4 μg·kg-1·min-1,间断静脉注射维库溴铵0.15 mg/kg,吸入七氟烷(呼气末浓度0.5%～1.0%).CPB期间通过体外循环机输入新鲜气体及2%～3%七氟烷.术中维持脑电双频谱指数40～50.于切皮前即刻(T1)、CPB开始5 min(T2)、降温结束后5 min(T3)、复温至鼻咽温37℃即刻(T4)、30 min(T5)及60 min(T6)时取右颈内静脉球部血样,测定血浆谷氨酸(Glu)、甘氨酸(Gly)及γ-氨基丁酸(GABA)浓度,计算兴奋性毒性指数.结果 与S组比较,P组T4-6时Glu浓度及兴奋性毒性指数降低,GABA浓度升高,L时Gly浓度升高(P<0.01).结论 异丙酚复合麻醉可抑制CPB复温期脑内兴奋性氨基酸释放,有助于兴奋性氨基酸与抑制性氨基酸水平的平衡.

Comparison of amino add levels in brain during different anesthesias in patients undergoing coronary artery bypass grafting under CPB

Objective To compare the amino acid levels in brain during different anesthesias in patients undergoing coronary artery bypass grafting (CABG) under CPB. Methods Eighty ASA Ⅱ or Ⅲ patients aged 45-64 yr undergoing CABG under CPB were randomly divided into 2 groups (n=40 each) : group Ⅰ propefol (P) and group Ⅱ sevoflurane (S). The patients were premeditated with intransuscular morphine 0.2 mg/kg and scopolamine 0.3 mg. Anesthesia was induced with midazolam, etomidate, fentanyl and vecuronium. The patients were mechanically ventilated after tracheal intubation. Anesthesia was maintained with TCI of propofol (target plasma concentration was set at 1-2 μg/ml) in group P or sevoflurane inhalation (end-tidal concentration 0.5%-1.0% ) in group S combined with remifentanil infusion at 0.2-0.4 μg·kg-1 ·min-1 and intermittent iv boluses of vecuronium.Radial artery was cannulated for BP monitoring. Right internal jugular vein was retrogradely cannulated for blood sampling. BIS was maintained at 40-50. Blood samples were taken from right jugular bulb immediately before incision (T1), at 5 min after the beginning of CPB (T2), at 5 min after termination of cooling (T3), immediately and at 30 and 60 min after nasepharyngeal temperature was rewarmed to 37℃(T4-6) for determination of plasma concentrations of glutamic acid (Glu),γ-aminobytyric acid (GABA) and glycine (Gly). The excitatory toxicity index (ETI) was calculated. Results Glu concentration and ETI were significantly lower, GABA concentration was significantly higher at T4-6 and Gly concentration higher at T4 in group P than in group S (P<0.01).Conclusion Propofol can inhibit the release of excitatory amino acids in the brain leading to a new balance between excitatory and inhibitory amino acids.