title: Direct comparison of cerebrovascular effects of norepinephrine and dopamine in head-injured patients.
abstract: OBJECTIVE
  To directly compare the cerebrovascular effects of norepinephrine and dopamine in patients with acute traumatic brain injury.
  
  
  METHODS
  Prospective randomized crossover trial.
  
  
  METHODS
  Neurosciences critical care unit of a university hospital.
  
  
  METHODS
  Ten acutely head-injured patients requiring vasoactive drugs to maintain a cerebral perfusion pressure of 65 mm Hg.
  
  
  METHODS
  Patients were randomized to start the protocol with either norepinephrine or dopamine. Using an infusion of the allocated drug, cerebral perfusion pressure was adjusted to 65 mm Hg. After 20 mins of data collection, cerebral perfusion pressure was increased to 75 mm Hg by increasing the infusion rate of the vasoactive agent. After 20 mins of data collection, cerebral perfusion pressure was increased to 85 mm Hg and again data were collected for 20 mins. Subsequently, the infusion rate of the vasoactive drug was reduced until a cerebral perfusion pressure of 65 mm Hg was reached and the drug was exchanged against the other agent. The protocol was then repeated.
  
  
  RESULTS
  Mean arterial pressure and intracranial pressure were monitored and cerebral blood flow was estimated with transcranial Doppler. Norepinephrine led to predictable and significant increases in flow velocity for each step increase in cerebral perfusion pressure (57.5+/-19.9 cm x sec, 61.3+/-22.3 cm x sec, and 68.4+/-24.8 cm x sec at 65, 75, and 85 mm Hg, respectively; p <.05 for all three comparisons), but changes with dopamine were variable and inconsistent. There were no differences between absolute values of flow velocity or intracranial pressure between the two drugs at any cerebral perfusion pressure level.
  
  
  CONCLUSIONS
  Norepinephrine may be more predictable and efficient to augment cerebral perfusion in patients with traumatic brain injury.
authors.affiliation: Academic Neurosurgery, Addenbrooke's Hospital, Cambridge, UK. lsteiner@uhbs.ch
authors.forename: Luzius A
authors.initials: LA
authors.lastname: Steiner
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Johnston
authors.forename: Marek
authors.initials: M
authors.lastname: Czosnyka
authors.forename: Doris A
authors.initials: DA
authors.lastname: Chatfield
authors.forename: Raymond
authors.initials: R
authors.lastname: Salvador
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Coles
authors.forename: Arun K
authors.initials: AK
authors.lastname: Gupta
authors.forename: John D
authors.initials: JD
authors.lastname: Pickard
authors.forename: David K
authors.initials: DK
authors.lastname: Menon
mesh_terms: D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D001930:Brain Injuries / Q000000981:diagnostic imaging / Q000188:drug therapy*; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D003422:Critical Care; D018592:Cross-Over Studies; D004298:Dopamine / Q000008:administration & dosage* / Q000009:adverse effects; D005260:Female; D015600:Glasgow Coma Scale; D006801:Humans; D007427:Intracranial Pressure / Q000187:drug effects; D008297:Male; D009638:Norepinephrine / Q000008:administration & dosage*; D012039:Regional Blood Flow / Q000187:drug effects; D013566:Sympathomimetics / Q000008:administration & dosage*; D016896:Treatment Outcome; D017585:Ultrasonography, Doppler, Transcranial; D014662:Vasoconstrictor Agents / Q000008:administration & dosage*
chemical_list: D013566:Sympathomimetics; D014662:Vasoconstrictor Agents; D004298:Dopamine; D009638:Norepinephrine