title: Dopamine therapy does not affect cerebral autoregulation during hypotension in newborn piglets.
abstract: BACKGROUND
  Hypotensive neonates who have been treated with dopamine have poorer neurodevelopmental outcome than those who have not been treated with dopamine. We speculate that dopamine stimulates adrenoceptors on cerebral arteries causing cerebral vasoconstriction. This vasoconstriction might lead to a rightward shift of the cerebral autoregulatory curve; consequently, infants treated with dopamine would have a higher risk of low cerebral blood flow at a blood pressure that is otherwise considered "safe".
  
  
  METHODS
  In anaesthetized piglets, perfusion of the brain, monitored with laser-doppler flowmetry, and cerebral venous saturation was measured at different levels of hypotension. Each piglet was studied in two phases: a phase with stepwise decreases in MAP and a phase with stepwise increases in MAP. We randomized the order of the two phases, whether dopamine was given in the first or second phase, and the infusion rate of dopamine (10, 25, or 40 μg/kg/min). In/deflation of a balloon catheter, placed in vena cava, induced different levels of hypotension. At each level of hypotension, fluctuations in MAP were induced by in/deflations of a balloon catheter in descending aorta.
  
  
  RESULTS
  During measurements, PaCO2 and arterial saturation were stable. MAP levels ranged between 14 and 82 mmHg. Cerebral autoregulation (CA) capacity was calculated as the ratio between %-change in cerebrovascular resistance and %-change in MAP induced by the in/deflation of the arterial balloon. A breakpoint in CA capacity was identified at a MAP of 38±18 mmHg without dopamine and at 44±18, 31±14, and 24±14 mmHg with dopamine infusion rates of 10, 25, and 40 μg/kg/min (p = 0.057). Neither the index of steady-state cerebral perfusion nor cerebral venous saturation were affected by dopamine infusion.
  
  
  CONCLUSIONS
  Dopamine infusion tended to improve CA capacity at low blood pressures while an index of steady-state cerebral blood flow and cerebral venous saturation were unaffected by dopamine infusion. Thus, dopamine does not appear to impair CA in newborn piglets.
authors.affiliation: Department of Neonatology, Copenhagen University Hospital - Rigshospitalet, Copenhagen, Denmark.|University of Copenhagen, Faculty of Health and Medical Sciences, Copenhagen, Denmark.
authors.forename: Vibeke Ramsgaard
authors.initials: VR
authors.lastname: Eriksen
authors.affiliation: Department of Neonatology, Copenhagen University Hospital - Rigshospitalet, Copenhagen, Denmark.|University of Copenhagen, Faculty of Health and Medical Sciences, Copenhagen, Denmark.
authors.forename: Martin Bo
authors.initials: MB
authors.lastname: Rasmussen
authors.affiliation: Department of Neonatology, Copenhagen University Hospital - Rigshospitalet, Copenhagen, Denmark.|Department of Pediatrics, Copenhagen University Hospital - Hvidovre Hospital, Hvidovre, Denmark.
authors.forename: Gitte Holst
authors.initials: GH
authors.lastname: Hahn
authors.affiliation: Department of Neonatology, Copenhagen University Hospital - Rigshospitalet, Copenhagen, Denmark.
authors.forename: Gorm
authors.initials: G
authors.lastname: Greisen
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001794:Blood Pressure / Q000187:drug effects; D001921:Brain / Q000187:drug effects / Q000473:pathology* / Q000503:physiopathology; D002560:Cerebrovascular Circulation / Q000187:drug effects; D004298:Dopamine / Q000494:pharmacology / Q000627:therapeutic use*; D006706:Homeostasis / Q000187:drug effects; D007022:Hypotension / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology; D034421:Sus scrofa
chemical_list: D004298:Dopamine