Significance of bispectral index monitoring in selecting the dose of propofol for induction of general anesthesia

Objective To study the significance of bispectral index(BIS) monitoring in selecting the dose of propofol for induction of general anesthesia in the elderly.Methods Forty patients,aged 65 to 75 years old and ASA class Ⅰ or Ⅱ,were randomly divided into two groups.The patients in group A were given intravenous injection of propofol at the dose of making BIS of 40～50,while those in group B were given propofol at the dose of 1.5～2.0 mg/kg.All patients received BIS monitoring and intubation after fentanyl 3 μk/kg and vecuronium 0.1 mg/kg injection.Blood pressure(BP) and heart rate(HR) were monitored continuously and the amount of propofol used for induction was recorded.Results The average dose of propofol for induction in group A was(1.33±0.50) mg/kg,which was significantly less than (1.62±0.7) mg/kg in group B(P0.05).BP and BIS in group B were obviously lower than those in group A.Conclusion The reasonable dose of propofol for induction of general anesthesia can be selected by BIS monitoring,which is about(1.33±0.50) mg/kg for the elderly to maintain adequate depth of anesthesia and prevent hypotension.