title: A dopamine infusion decreases propofol concentration during epidural blockade under general anesthesia.
abstract: OBJECTIVE
  It is common clinical practice to use dopamine to manage the reduction in blood pressure accompanying epidural blockade. As propofol is a high-clearance drug, propofol concentrations can be influenced by cardiac output (CO). The purpose of the present study was to investigate the effects of dopamine infusions on propofol concentrations administered by a target-controlled infusion system during epidural block under general anesthesia.
  
  
  METHODS
  12 patients undergoing abdominal surgery were enrolled in this study. Anesthesia was induced with propofol and vecuronium 0.1 mg.kg(-1), and maintained using 67% nitrous oxide, sevoflurane in oxygen and constant infusion of propofol. Propofol was administered to all subjects via target-controlled infusion to achieve a propofol concentration at 6.0 microg.mL(-1) at intubation and 2.0 microg.mL(-1) after intubation. Before and after the administration of 10 mL of 1.5% mepivacaine from the epidural catheter and dopamine infusion at 5 microg.kg(-1).min(-1), CO and effective liver blood flow (LBF) were measured using indocyanine green. Blood propofol concentration was also determined using high-performance liquid chromatography.
  
  
  RESULTS
  At one hour after epidural block and dopamine infusion, CO was significantly increased from 4.30 +/- 1.07 L.min(-1) to 5.82 +/- 0.98 L.min(-1) (P < 0.0001), and effective LBF was increased 0.75 +/- 0.17 L.min(-1) to 0.96 +/- 0.18 L.min(-1) (P < 0.0001). Propofol concentration was significantly decreased from 2.13 +/- 0.24 microg.mL(-1) to 1.59 +/- 0.29 microg.mL(-1) (P < 0.0001).
  
  
  CONCLUSIONS
  Propofol concentrations decrease with an increase in CO, suggesting the possibility of inadequate anesthetic depth following catecholamine infusion during propofol anesthesia.
authors.affiliation: Department of Anesthesiology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi City 371-8511, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Takizawa
authors.forename: Koichi
authors.initials: K
authors.lastname: Nishikawa
authors.forename: Eri
authors.initials: E
authors.lastname: Sato
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Hiraoka
authors.forename: Koujirou
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Shigeru
authors.initials: S
authors.lastname: Saito
authors.forename: Ryuya
authors.initials: R
authors.lastname: Horiuchi
authors.forename: Fumio
authors.initials: F
authors.lastname: Goto
mesh_terms: D000368:Aged; D000767:Anesthesia, Epidural; D000768:Anesthesia, General; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D004298:Dopamine / Q000494:pharmacology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015742:Propofol / Q000008:administration & dosage / Q000493:pharmacokinetics*
chemical_list: D004298:Dopamine; D015742:Propofol