Effect of the laryngeal mask insertion during the induction of general anesthesia with remifentanil or different doses of dezocine on the half-effective target plasma concentration of propofol

Objective: To explore the effects of the laryngeal mask insertion during the induction of general anesthesia with remifentanil or different doses of dezocine on the half-effective target plasma concentration(Cp50) of propofol.Methods: One hundred and sixty patients scheduled by operation with general anesthesia were randomly divided into the group A,B,C and D(40 cases each group).The group B,C and D were treated with initial target controlled infusion of 3 μg/mL propofol,and group A were treated with initial target controlled infusion of 5 μg/mL propofol.The group B,C and D were treated with target controlled infusion of 2 ng/ml remifentanil,0.1 mg/kg dezocine and 0.15 mg/kg dezocine,respectively,and the group A were the same volume 0.9% sodium chloride injection.Laryngeal mask were placed after 20 minutes.The heart rate(HR),mean arterial pressure(MAP) and bispectral index(BIS) in all patients before induction of anesthesia,before laryngeal mask placing and at the time of laryngeal mask placement were recorded,and the propofol Cp50 were measured using the upper and lower cross method.Results: Before laryngeal mask,the HR in group A,C and D were significantly higher than that in group B(P<0.01),the HR in group C was significantly higher than that in group A and D(P<0.01),and the MAP in group B,C and D were significantly higher than that in group A(P<0.01).At the time of laryngeal mask placement,the HR in group B and D were significantly lower than that in group A and C(P<0.01).Compared with that of before induction of anesthesia,the HR in group B,C and D decreased significantly(P<0.01),and the MAP and BIS in all groups decreased significantly before laryngeal mask placing(P<0.01).Compared with that of before laryngeal mask placing,the HR,MAP and BIS in group A and B increased(P<0.05 to P<0.01),the MAP and BIS in group C increased(P<0.05),propofol Cp50 in groups B,C and D were significantly lower than that in group A(P<0.05),and propofol Cp50 in groups B and D were significantly lower than that in group C at the time of laryngeal mask placing(P<0.01).Conclusions: Remifentanil or 0.15 mg/kg dezocine can effective reduce the effective dose of propofol Cp50,but the dezocine in hemodynamics is more stable than that of remifentanil during the induction of general anesthesia and laryngeal mask.