title: Effects of epidural anesthesia with 0.2% and 1% ropivacaine on predicted propofol concentrations and bispectral index values at three clinical end points.
abstract: OBJECTIVE
  To compare the effects of 0.2% epidural ropivacaine and those of 1% epidural ropivacaine on predicted propofol concentrations and bispectral index scores (BISs) at three clinical end points.
  
  
  METHODS
  Randomized double-blind study.
  
  
  METHODS
  University hospital.
  
  
  METHODS
  Thirty-five (35) ASA physical status I and II patients scheduled for elective surgery of the lower abdomen.
  
  
  METHODS
  Patients were randomly divided into 2 groups to receive epidurally 8 mL of 0.2% or 1% ropivacaine followed by the same solution at a rate of 6 mL/h.
  
  
  METHODS
  Twenty minutes after starting ropivacaine, a target-controlled infusion of propofol was started to provide a predicted blood concentration of 3 microg/mL; it increased by 0.5 microg/mL every 60 seconds until all 3 clinical end points were reached, as follows: P1, when patients lost consciousness; P2, when patients failed to show pupillary dilation and skin vasomotor reflex to transcutaneous electric stimulation applied to the upper level of loss of cold sensation; and P3, when patients failed to show pupillary dilation and skin vasomotor reflex to transcutaneous electric stimulation applied to C5.
  
  
  RESULTS
  The effective concentration 50 values for both predicted blood and effect-site propofol concentrations were significantly larger in the 0.2% group than in the 1% group at all end points. The BIS at every end point was significantly smaller in the 0.2% group than in the 1% group.
  
  
  CONCLUSIONS
  During combined epidural-propofol anesthesia, unconsciousness and lack of response to noxious stimulation occurred at lower predicted concentrations with 1% epidural ropivacaine than with 0.2% epidural ropivacaine. The results also suggest that the BIS may not be a good indicator when propofol anesthesia is combined with epidural anesthesia.
authors.affiliation: Department of Anesthesiology, Shimane University School of Medicine, Izumo City 693-8501, Japan.
authors.forename: Kazue
authors.initials: K
authors.lastname: Kanata
authors.forename: Shinichi
authors.initials: S
authors.lastname: Sakura
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kushizaki
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Nakatani
authors.forename: Yoji
authors.initials: Y
authors.lastname: Saito
mesh_terms: D000328:Adult; D000577:Amides / Q000008:administration & dosage*; D000767:Anesthesia, Epidural; D000779:Anesthetics, Local / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004569:Electroencephalography / Q000187:drug effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015742:Propofol / Q000008:administration & dosage / Q000097:blood*; D000077212:Ropivacaine
chemical_list: D000577:Amides; D000779:Anesthetics, Local; D000077212:Ropivacaine; D015742:Propofol