Effects Of Different Doses Of Fentanyl On The Target Effect-site Concentration Of Tci Propofol And Bispectral Index During Anesthesia Induction

Objective: To investigate the effects of different doses of fentanyl on the effect-site concentration (Ce) of target controlled infusion (TCI) of propofol, bispectral index and hemodynamics during anesthesia induction and appropriate dose of fentanyl. Methods: Eigty four patients who scheduled for orthepedics surgery with general anesthesia were enrolled , ASAⅠorⅡ, aged 19~63 yr, weighting 47~91 kg, both sexes, were divided into 4 groups according to different induction doses of fentanyl : fentanyl 2μg/kg group ( group G1, n=21) , fentanyl 4μg/kg group ( group G2, n=21) , fentanyl 6μg/kg group ( group G3, n=21) , fentanyl 8μg/kg group ( group G4, n=21) . Anesthesia was induced with iv injection of fentanyl 2μg/kg , 4μg/kg , 6μg/kg and 8μg/kg within 1 min, 4 min later , TCI of propofol. The target effect-site concentration was set initially at 1. 5μg/ml followed by increasments of 0. 5μg/ml every 5 min until the BIS decreased to (45±5) . Tracheal intubation was facilitated with vecuronium 0. 1 mg/kg iv . The patients were mechanically ventilated . Systolic pressure (SBP) , heart rate (HR) , BIS were recorded before induction of anesthesia (T0) , at 4 min after injection of fentanyl (T1) , lost of consciouse (T2) , the BIS decreased to (45±5) (T3) , at 4 min after injection vecuronium (T4) , immediately (T5) and at 1 min (T6) , 3 min (T7) , 5 min (T8) after tracheal intubation . The Ce and consumption of propofol at T2 , T3 , the time from T1 to T2 (T1-2) , T1 to T3 (T1-3) and the devise cardiovascular events including bradycardia , tachycardia , hypertension , hypotension and cough and hiccup were also recorded . Results: The effect-site concentration (Ce) of TCI of propofol at T2 and T3 were significantly smaller in the groups of fentanyl G2, G3, G4 than G1 (P<0. 05) . The Ce value were no differences between the groups of fentanyl G2 and G3 (P>0. 05) at the time pionts of T2 and T3. There was significantly decrease between T0 and T1 about BIS in all groups (P<0. 05) . The decreases of BIS in G2, G3 , G4 were significantly more than G1 between T0 and T1 . The incidence of intubation response was significantly higher in the groups of G1 than in the orther 3 groups (P<0.05) . The incidences of bradycardia and cough, hiccup were significantly higher in the groups of G3 , G4 than in G1 , G2 (P<0.05) . Conclusion: Four doses of fentanyl could enhance the sedation of propofol and reduce the time of anesthesia induction. The synergism of fentanyl 4μg/kg is more significant and the hemodynamics and BIS are more stable.