RESUMEN
Objective To compare the effects of target-controlled infusion(TCI) of remifentanil in three different doses in thoracic patients undergoing total intravenous anesthesia.Methods Forty-five ASA Ⅰ～Ⅱ patients aged 40～60yr undergoing thoracic surgery were randomly divided into three groups.The patients were given midazolam 0.05mg/kg and artropine 0.5 mg/kg i.m.before anesthesia.Anesthesia was induced with remifentanil and propofol both given by TCI simultaneously.The target concentration of propofol was set at 3?g/ml and remifentanil at 4,6,8ng/ml(groupⅠ,Ⅱ,Ⅲ).When the patients lost conscionsness,rocuronium 0.6mg/kg was given i.v.to facilitate intubation.Anesthesia was maintained with TCI of propofol-remifentanil and intermittent i.v.boluses of rocuronium.Remifentanil target concentration maintained unchanged during anesthesia.BIS index was controlled at 45～55 by modify propofol target concentration.SBP,DBP,MAP,HR and BIS index was recorded in baseline(T0),before intubation(T1),intubation(T2),skin incision(T3),the opening of the chest(T4),skin closuer(T5),extubation(T6).Vein blood samples were taken for determination of plasma concentration of epinephrine(E) and norepinephrine(NE) by ELASA.Results SBP,DBP,MAP,HR and plasma NE concentration at T2,T3,T4,T5 were higher than T0 in group Ⅰ(P