Half Effective Dose Of Nalbuphine To Inhibit Responses To Laryngeal Mask Insertion In Different Patients

Objective:To determine the median effective dose(ED₅₀)and 95%confidence interval（CI）of nalbuphine inhibiting responses to laryngeal mask insertion.Methods:Patients scheduled for elective minor surgery under general anesthesia were divided into four groups according to gender and age:group F（female）,group M（male）,group O（50～70 years old）and group Y（18～49 years old）.Trials were conducted independently and simultaneously in the 4 groups.After nalbuphine was administered intravenously at an initial dose of 0.1 mg/kg for 3 min,propofol was infused by target-controlled infusion（TCI）until the target effect-site concentration reached 3.5ug/ml.The laryngeal mask airway（LMA）was inserted when bispectral index（BIS）value reached 50～60.The"three-level and six-point method"was used to evaluate whether the LMA was satisfying insert.If the insertion was satisfactory,the dose of nalbuphine for the next patient was reduced by 10%,otherwise,the dose was increased by 10%.The ED₅₀and 95%CI of nalbuphine inhibiting responses to LMA insertion were calculated by probit method.The mean blood pressure（MAP）and heart rate（HR）were recorded at admission（T₀）,3 min after nalbuphine injection（T₁）,before LMA insertion（T₂）and after LMA insertion（T₃）.Results:A total of 128 patients were examined in this experiment.The ED₅₀（95%CI）of nalbuphine inhibiting responses to LMA insertion were F group 0.073mg/kg（0.001～0.1mg/kg）,M group 0.070mg/kg（0.011～0.088 mg/kg）,O group 0.047mg/kg（0.013～0.064mg/kg）and Y group 0.088mg/kg（0.016～0.128 mg/kg）respectively.Comparison of MAP and HR at T₀ and T₁ in each group showed that nalbuphine reduced only HR in elderly patients（P=0.007）.Comparison of MAP and HR at T₂ and T₃ in each group showed that there was no significant change in MAP in each group when LMA was satisfying insert,but MAP and HR were higher in T₃ compared to T₂ in all groups with unsatisfactory laryngeal mask insertion.Conclusions:The ED₅₀and 95%CI of nalbuphine inhibiting responses to LMA insertion were F group 0.073mg/kg（0.001～0.1 mg/kg）,M group 0.070mg/kg（0.011～0.088 mg/kg）,O group 0.047mg/kg（0.013～0.064 mg/kg）and Ygroup 0.088mg/kg（0.016～0.128 mg/kg）respectively.Nalbuphine has little effect or no effect on hemodynamics and,at adequate doses,is effective in suppressing the response to LMA insertion and inhibiting sympathetic nerve stimulation triggered by LMA insertion.