title: Influence of atropine on the dose requirements of propofol in humans.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the effect of atropine on the dose requirement of propofol for induction of anesthesia and propofol concentrations during continuous infusion.
  
  
  METHODS
  Study 1: Forty patients were randomly allocated to the control or atropine groups. Induction of anesthesia commenced 3 min following the administration of 0.9% saline or atropine (0.01 mg kg(-1)), using a Diprifuser set to achieve propofol concentration of 6.0 microg mL(-1). The primary end point was the propofol dose per kg at the moment of loss of response to a command. Study 2: Fifteen patients undergoing elective surgery were enrolled. Propofol was administered to all subjects via target-controlled infusion to achieve a propofol concentration at 2.0 microg mL(-1) after intubation. Before and after administration of atropine (0.01 mg kg(-1)), cardiac output (CO) was measured using indocyanine green as an indicator and blood propofol concentration was determined using high-performance liquid chromatography.
  
  
  RESULTS
  Study 1: The propofol dose for each group was 2.22+/-0.21 mg kg(-1) for control group and 2.45+/-0.28 mg kg(-1) for atropine, respectively (p=0.014). Study 2: After the administration of atropine, CO was significantly increased from 4.28+/-0.83 to 5.76+/-1.55 l min(-1) (p<0.0001). Propofol concentration was significantly decreased from 2.12+/-0.28 to 1.69+/-0.27 microg mL(-1) (p<0.0001).
  
  
  CONCLUSIONS
  Following the administration of atropine, the propofol requirements for the induction of anesthesia were increased and propofol concentrations were decreased during continuous infusion by the administration of atropine.
authors.affiliation: Department of Anesthesiology, Graduate School of Medicine, Gunma University, Showa-machi, Maebashi, Japan.
authors.forename: Eri
authors.initials: E
authors.lastname: Takizawa
authors.forename: Daisuke
authors.initials: D
authors.lastname: Takizawa
authors.forename: Wael S
authors.initials: WS
authors.lastname: Al-Jahdari
authors.forename: Mitsue
authors.initials: M
authors.lastname: Miyazaki
authors.forename: Katsunori
authors.initials: K
authors.lastname: Nakamura
authors.forename: Koujirou
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Ryuya
authors.initials: R
authors.lastname: Horiuchi
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Hiraoka
mesh_terms: D000328:Adult; D000758:Anesthesia / Q000379:methods; D018686:Anesthetics, Intravenous / Q000008:administration & dosage / Q000493:pharmacokinetics; D001285:Atropine / Q000008:administration & dosage / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D002851:Chromatography, High Pressure Liquid; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D007552:Isotonic Solutions / Q000008:administration & dosage; D008297:Male; D008875:Middle Aged; D010276:Parasympatholytics / Q000008:administration & dosage / Q000494:pharmacology; D015742:Propofol / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics; D000077325:Ringer's Lactate
chemical_list: D018686:Anesthetics, Intravenous; D007552:Isotonic Solutions; D010276:Parasympatholytics; D000077325:Ringer's Lactate; D001285:Atropine; D015742:Propofol