Effect of target controlled infusion of remifentanil on bispectral index

Objective To evaluate the effect of target controlled infusion(TCI)remifentanil on bispectral index.Methods Sixty ASA class Ⅰ patients without premedication were randomly assigned to one of the four groups with 15 cases each,TCI of remifentanil was initiated 5 minutes after TCI of propofol given at the target plasma concentration of 3 μg/ml.After the loss of consciousness,vecuronium 0.1 mg/kg was administrated.Ventilation was adjusted to maintain end-tidal carbon dioxide partial pressure between 35-45 mmHg.Mean arterial pressure(MAP),heart rate(HR),bispectral index(BIS)were measured continuously from the baseline to 5 minutes after tracheal intubation.MAP,HR,BIS were obtained on the time points of before induction(T0),before remifentanil TCI(T1),before laryngoscopy(T2),and maximum values after intubation(T3).Results BIS values were not affected by remifentanil before laryngoscopy.In group R2(remifentanil 2 ng/ml),BIS,MAP,HR were significantly higher after intubation than those before,BIS changes were consistent with hemodynamic responses.Conclusion The addition of remifentanil to propofol did not affect BIS without a painful stimulus,BIS can guide the administration of propofol.4 ng/ml remifentanil TCI was the optimal dose for the intubation.