title: Metabolic effects of three different inotropic strategies in the newborn piglet myocardium.
abstract: BACKGROUND
  Neonates undergoing congenital heart surgery frequently need post-operative inotropic support. Knowledge about the effect of inotropes on myocardial metabolism in the newborn heart is limited, and the choice of inotropic therapy is based mainly on evidence from studies in adults. The aim of this study was to compare the effect of three inotropic strategies on the myocardial metabolism in a neonatal pig model.
  
  
  METHODS
  Newborn piglets were randomised to intravenous infusions with: adrenaline and milrinone; dopamine and milrinone; dobutamine in haemodynamically equivalent doses; or isotonic saline, through 3 h. Microdialysis catheters were inserted in the myocardium of the left and right ventricle, and concentrations of lactate, pyruvate, glycerol, and glucose were measured in the microdialysate. In myocardial biopsies, tissue lactate and intracellular glycogen concentrations were determined, and arterial blood samples were analysed for lactate and glucose.
  
  
  RESULTS
  No statistically significant differences were observed in haemodynamics between the three interventions. Metabolic variables demonstrated a consistent increase in lactate concentration in blood, myocardial dialysate, and biopsies in milrinone-adrenaline-treated animals. The lactate concentration remained stable in all other groups in all samples. The myocardial lactate/pyruvate ratio did not increase and was not significantly different between groups.
  
  
  CONCLUSIONS
  Milrinone and adrenaline induced significantly higher lactate levels in neonatal piglets. The increase was not caused by myocardial ischaemia, but rather due to a beta-stimulation-induced glycolysis.
authors.affiliation: Department of Anaesthesiology and Intensive Care Medicine, Aarhus University Hospital, Skejby, Denmark. piacolding@gmail.com
authors.forename: P D
authors.initials: PD
authors.lastname: Colding
authors.forename: L M
authors.initials: LM
authors.lastname: Kolstrup
authors.forename: J A
authors.initials: JA
authors.lastname: Hyldebrandt
authors.forename: M R
authors.initials: MR
authors.lastname: Schmidt
authors.forename: H E
authors.initials: HE
authors.lastname: Bøtker
authors.forename: H B
authors.initials: HB
authors.lastname: Ravn
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002316:Cardiotonic Agents / Q000008:administration & dosage*; D004280:Dobutamine / Q000008:administration & dosage; D004298:Dopamine / Q000494:pharmacology; D004837:Epinephrine / Q000008:administration & dosage; D006439:Hemodynamics / Q000187:drug effects; D019344:Lactic Acid / Q000378:metabolism; D017551:Microdialysis; D020105:Milrinone / Q000008:administration & dosage; D009206:Myocardium / Q000378:metabolism*; D019289:Pyruvic Acid / Q000378:metabolism; D013552:Swine
chemical_list: D002316:Cardiotonic Agents; D019344:Lactic Acid; D004280:Dobutamine; D019289:Pyruvic Acid; D020105:Milrinone; D004298:Dopamine; D004837:Epinephrine