title: Cerebral effects of commonly used vasopressor-inotropes: a study in newborn piglets.
abstract: BACKGROUND
  Despite widespread use in sick infants, it is still debated whether vasopressor-inotropes have direct cerebral effects that might affect neurological outcome. We aimed to test direct cerebrovascular effects of three commonly used vasopressor-inotropes (adrenaline, dopamine and noradrenaline) by comparing the responses to those of nonpharmacologically induced increases in blood pressure. We also searched for reasons for a mismatch between the response in perfusion and oxygenation.
  
  
  METHODS
  Twenty-four piglets had long and short infusions of the three vasopressor-inotropes titrated to raise mean arterial blood pressure (MAP) 10 mmHg in random order. Nonpharmacological increases in MAP were induced by inflation of a balloon in the descending aorta. We measured cerebral oxygenation (near-infrared spectroscopy), perfusion (laser-Doppler), oxygen consumption (co-oximetry of arterial and superior sagittal sinus blood), and microvascular heterogeneity (side stream dark field video microscopy).
  
  
  RESULTS
  Vasopressor-inotropes increased cerebral oxygenation significantly less (p≤0.01) compared to non-pharmacological MAP increases, whereas perfusion was similar. Furthermore, cerebral total hemoglobin concentration increased significantly less during vasopressor-inotrope infusions (p = 0.001). These physiologic responses were identical between the three vasopressor-inotropes (p>0.05). Furthermore, they induced a mild, although insignificant increase in cerebral metabolism and microvascular heterogeneity (p>0.05). Removal of the scalp tissue did not influence the mismatch (p>0.05).
  
  
  CONCLUSIONS
  We demonstrated a moderate vasopressor-inotrope induced mismatch between cerebral perfusion and oxygenation. Scalp removal did not affect this mismatch, why vasopressor-inotropes appear to have direct cerebral actions. The statistically nonsignificant increases in cerebral metabolism and/or microvascular heterogeneity may explain the mismatch. Alternatively, it may simply reflect a vasopressor-inotrope-induced decrease in the arterial-to-venous volume ratio as detected by near-infrared spectroscopy.
authors.affiliation: Department of Neonatology, Copenhagen University Hospital-Rigshospitalet, Copenhagen, Denmark. gitte.holst.hahn@gmail.com
authors.forename: Gitte H
authors.initials: GH
authors.lastname: Hahn
authors.forename: Simon
authors.initials: S
authors.lastname: Hyttel-Sorensen
authors.forename: Sandra M
authors.initials: SM
authors.lastname: Petersen
authors.forename: Ole
authors.initials: O
authors.lastname: Pryds
authors.forename: Gorm
authors.initials: G
authors.lastname: Greisen
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001794:Blood Pressure / Q000187:drug effects; D015687:Cell Hypoxia; D002540:Cerebral Cortex / Q000098:blood supply* / Q000187:drug effects / Q000378:metabolism; D004298:Dopamine / Q000494:pharmacology*; D004837:Epinephrine / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology; D009638:Norepinephrine / Q000494:pharmacology*; D010101:Oxygen Consumption / Q000187:drug effects; D012039:Regional Blood Flow / Q000187:drug effects; D034421:Sus scrofa; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
chemical_list: D014662:Vasoconstrictor Agents; D004298:Dopamine; D009638:Norepinephrine; D004837:Epinephrine