title: Dopamine or norepinephrine infusion during thoracic epidural anesthesia? Differences in hemodynamic effects and plasma catecholamine levels.
abstract: BACKGROUND
  During thoracic epidural anesthesia, an intravenous dopamine infusion augments the systemic pressure response and modifies plasma catecholamine levels. If such an altered response occurs when norepinephrine is infused is not clear. Therefore, dopamine and norepinephrine induced circulatory and catecholamine responses were studied before and during thoracic epidural anesthesia.
  
  
  METHODS
  Nine chloralose-anesthetized dogs were equipped with thoracic epidural catheters. Dopamine (5, 10, and 20 microg kg(-1) min(-1)), and norepinephrine (0.1, 0.25, and 0.5 microg kg(-1) min(-1)) were infused before and during epidural anesthesia, while cardiovascular performance and plasma catecholamine changes were studied.
  
  
  RESULTS
  Thoracic epidural anesthesia decreased arterial pressure, and cardiac contractility. The systemic pressure response induced by dopamine was augmented during epidural anesthesia. Norepinephrine did not increase arterial pressure and myocardial contractility as markedly as dopamine, and cardiac output was not altered. Thoracic epidural anesthesia attenuated the plasma norepinephrine level. Plasma dopamine levels were augmented by the dopamine infusion during epidural anesthesia, while plasma norepinephrine levels were attenuated. In contrast, norepinephrine augmented the plasma norepinephrine levels during epidural anesthesia. In general, plasma norepinephrine levels were three to six times higher during a norepinephrine infusion compared to a dopamine infusion.
  
  
  CONCLUSIONS
  The cardiovascular response to a graded dopamine infusion is augmented during thoracic epidural anesthesia, while norepinephrine-induced effects are unaltered. The modified plasma catecholamine levels may contribute to the hemodynamic differences between dopamine and norepinephrine infusions during thoracic epidural anesthesia.
authors.affiliation: Department of Anesthesiology and Intensive Care, University Hospital, Lund, Sweden. johan.lundberg@skane.se
authors.forename: J F
authors.initials: JF
authors.lastname: Lundberg
authors.forename: J
authors.initials: J
authors.lastname: Martner
authors.forename: C
authors.initials: C
authors.lastname: Raner
authors.forename: O
authors.initials: O
authors.lastname: Winsö
authors.forename: B
authors.initials: B
authors.lastname: Biber
mesh_terms: D000767:Anesthesia, Epidural; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D002395:Catecholamines / Q000097:blood*; D004285:Dogs; D004298:Dopamine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D008619:Mepivacaine / Q000097:blood; D009638:Norepinephrine / Q000494:pharmacology*; D013904:Thoracic Vertebrae; D016277:Ventricular Function, Left / Q000187:drug effects
chemical_list: D002395:Catecholamines; D008619:Mepivacaine; D004298:Dopamine; D009638:Norepinephrine