title: Resuscitation with pressors after traumatic brain injury.
abstract: BACKGROUND
  The purpose of the study was to compare initial resuscitation with arginine vasopressin (AVP), phenylephrine (PE), or isotonic crystalloid fluid alone after traumatic brain injury and vasodilatory shock.
  
  
  METHODS
  Anesthetized, ventilated swine (n = 39, 30 +/- 2 kg) underwent fluid percussion traumatic brain injury followed by hemorrhage (30 +/- 2mL/kg) to a mean arterial pressure < 30mmHg, then were randomized to 1 of 5 groups to maintain mean arterial pressure > 60mmHg for 30 to 60minutes, then cerebral perfusion pressure > 60mmHg for 60 to 300minutes, either unlimited crystalloid fluid only (n = 9), arginine vasopressin + fluid (n = 9), phenylephrine + fluid (n = 9), arginine vasopressin only (n = 5), or phenylephrine only (n = 5). Heterologous transfusions were administered if hematocrit was < 13, and mannitol was administered if intracranial pressure was > 20 mmHg. Cerebrovascular reactivity was evaluated with serial CO(2) challenges.
  
  
  RESULTS
  In all groups, physiologic variables were similar at baseline and at the end of shock. On resuscitation, all achieved mean arterial pressure and cerebral perfusion pressure goals. Brain tissue PO(2)s were similar. With fluid only, more blood and mannitol were required, intracranial pressure and peak inspiratory pressure were higher, and cerebrovascular reactivity was decreased (all p < 0.05 versus pressor + fluid). With either pressor + fluid, cardiac output, heart rate, lactate, and mixed venous O(2) saturation were similar to fluid only, but total fluid requirements and urine output were both reduced (p < 0.05). With either pressor only, intracranial pressure remained low, but mixed venous O(2) saturation, cardiac output, and urine output were decreased (all p < 0.05 versus other groups).
  
  
  CONCLUSIONS
  To correct vasodilatory shock after traumatic brain injury, a resuscitation strategy that combined either phenylephrine or arginine vasopressin plus crystalloid was superior to either fluid alone or pressor alone.
authors.affiliation: Dewitt-Daughtry Family Department of Surgery, Division of Trauma, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
authors.forename: Ara J
authors.initials: AJ
authors.lastname: Feinstein
authors.forename: Mayur B
authors.initials: MB
authors.lastname: Patel
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Sanui
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Cohn
authors.forename: Matthias
authors.initials: M
authors.lastname: Majetschak
authors.forename: Kenneth G
authors.initials: KG
authors.lastname: Proctor
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D001930:Brain Injuries / Q000628:therapy*; D000077324:Crystalloid Solutions; D007552:Isotonic Solutions; D010656:Phenylephrine / Q000494:pharmacology*; D010952:Plasma Substitutes / Q000494:pharmacology; D011897:Random Allocation; D012151:Resuscitation / Q000379:methods*; D012771:Shock, Hemorrhagic / Q000628:therapy*; D018709:Statistics, Nonparametric; D013552:Swine; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
chemical_list: D000077324:Crystalloid Solutions; D007552:Isotonic Solutions; D010952:Plasma Substitutes; D014662:Vasoconstrictor Agents; D001127:Arginine Vasopressin; D010656:Phenylephrine