title: Low dose of fentanyl reduces predicted effect-site concentration of propofol for flexible laryngeal mask airway insertion.
abstract: OBJECTIVE
  In contrast to reports on the classical laryngeal mask airway (classical LMA; CLMA), no report has calculated the 50% and 95% effect-site concentrations (EC(50) and EC(95), respectively) of propofol required for flexible LMA (FLMA) insertion. This study was designed to determine the EC(50) and EC(95) of propofol for FLMA insertion, using probit analysis, and to investigate whether supplemental 0.25 microg x kg(-1) fentanyl decreased these concentrations.
  
  
  METHODS
  Fifty-nine unpremedicated patients who were scheduled for elective minor oral surgery were randomly allocated to a saline-propofol group (S-P group; n = 30) or a fentanyl-propofol group (F-P group; n = 29). Each group was further divided into four subgroups, in which the propofol EC for FLMA insertion was set at 2.5, 3.0, 3.5, and 4.0 microg x ml(-1), respectively, in the S-P group and 1.8, 2.0, 2.5, and 3.0 microg x ml(-1), respectively, in the F-P group. The experiment was assessed as "successful" when FLMA insertion within 1 min was possible.
  
  
  RESULTS
  The EC(50) and EC(95) in the S-P group were 3.29 (95% confidence interval [CI], 2.83-3.93) and 4.73 (95% CI, 3.94-12.22) microg x ml(-1), and those in the F-P group were 2.13 (95% CI, 1.42-2.60) and 3.54 95% CI, (2.78-34.78) microg x ml(-1), respectively. The EC(50) in the F-P group was significantly lower than that in the S-P group. There were no significant differences in bispectral index (BIS), hemodynamic variables, respiratory rate, and arterial oxygen saturation (SpO2) between the S-P and F-P groups.
  
  
  CONCLUSIONS
  The propofol EC(50) for FLMA insertion was decreased by supplemental 0.25 microg x kg(-1) fentanyl without BIS, hemodynamic, or respiratory depression.
authors.affiliation: Department of Dental Anesthesiology, Tokyo Dental College, 1-2-2 Masago, Mihama-ku, Chiba, 261-8502, Japan.
authors.forename: Junko
authors.initials: J
authors.lastname: Yumura
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Koukita
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Fukuda
authors.forename: Yuzuru
authors.initials: Y
authors.lastname: Kaneko
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Ichinohe
mesh_terms: D000293:Adolescent; D000328:Adult; D000465:Algorithms; D018686:Anesthetics, Intravenous / Q000493:pharmacokinetics*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004569:Electroencephalography / Q000187:drug effects; D005260:Female; D005283:Fentanyl / Q000494:pharmacology*; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D006993:Hypnotics and Sedatives / Q000493:pharmacokinetics*; D017214:Laryngeal Masks; D008297:Male; D008875:Middle Aged; D019647:Oral Surgical Procedures; D010100:Oxygen / Q000097:blood; D011229:Preanesthetic Medication; D015742:Propofol / Q000493:pharmacokinetics*; D055815:Young Adult
chemical_list: D018686:Anesthetics, Intravenous; D006993:Hypnotics and Sedatives; D010100:Oxygen; D005283:Fentanyl; D015742:Propofol