title: Tissue oxygenation during management of cerebral perfusion pressure with phenylephrine or vasopressin.
abstract: OBJECTIVE
  Phenylephrine is often used for management of cerebral perfusion pressure after traumatic brain injury, but can have undesirable actions. Few studies have evaluated alternatives. The hypothesis was that arginine vasopressin was as effective as phenylephrine for maintaining tissue oxygenation during cerebral perfusion pressure management.
  
  
  METHODS
  Prospective randomized, blinded animal study.
  
  
  METHODS
  University laboratory.
  
  
  METHODS
  Thirty-five anesthetized swine (46 +/- 1 kg).
  
  
  METHODS
  Blunt trauma to the head and bilateral chests (estimated injury severity score was 25-32) was followed by hypoventilation. Resuscitation was divided into phases to simulate treatment in a typical prehospital, emergency room, and intensive care unit. For 30-45 mins postinjury, 1 L of normal saline was administered. For 45-120 mins, normal saline maintained systolic blood pressure >100 mm Hg plus mannitol for intracranial hypertension. After 120 mins, phenylephrine or arginine vasopressin was titrated to cerebral perfusion pressure >70 mm Hg (randomized and blinded) plus normal saline to maintain filling pressure >12 mm Hg plus glucose to maintain normoglycemia.
  
  
  RESULTS
  Mortality rate was 37% (13 of 35) within 2 hrs. Before resuscitation, mean arterial pressure was 61 +/- 5 mm Hg, heart rate was 110 +/- 6 beats/min, PaO2 was 46 +/- 2 mm Hg, and lactate was 5.0 +/- 0.4 mM. Intracranial pressure increased from 8 +/- 1 mm Hg to 20 +/- 1 mm Hg and brain tissue PO2 decreased from 19 +/- 1 mm Hg to 8 +/- 1 mm Hg. Resuscitation corrected most variables, as well as mixed venous, renal, portal, and muscle oxygen saturations, but 90% (20 of 22) required pressor support. After 6 hrs with either pressor, hemodynamics were stable. However, with phenylephrine vs. arginine vasopressin, intracranial pressure averaged >10 mm Hg higher and brain tissue PO2 was 6 mm Hg lower, whereas tissue oxygen saturations were >10% higher in the shoulder and hindlimb muscles (all p < 0.05).
  
  
  CONCLUSIONS
  Arginine vasopressin was as effective as phenylephrine for maintaining cerebral perfusion pressure, but intracranial pressure and brain tissue oxygenation were improved at the expense of the periphery.
authors.affiliation: Dewitt-Daughtry Family Department of Surgery, Division of Trauma, University of Miami Miller School of Medicine, Miami, FL, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Dudkiewicz
authors.forename: Kenneth G
authors.initials: KG
authors.lastname: Proctor
mesh_terms: D000818:Animals; D001127:Arginine Vasopressin / Q000627:therapeutic use*; D001772:Blood Cell Count; D001784:Blood Gas Analysis; D001921:Brain / Q000098:blood supply / Q000187:drug effects / Q000378:metabolism; D002560:Cerebrovascular Circulation / Q000187:drug effects; D005260:Female; D016489:Head Injuries, Closed / Q000188:drug therapy* / Q000503:physiopathology; D007427:Intracranial Pressure / Q000187:drug effects*; D008297:Male; D009104:Multiple Trauma / Q000188:drug therapy* / Q000503:physiopathology; D010100:Oxygen / Q000378:metabolism*; D010656:Phenylephrine / Q000627:therapeutic use*; D011897:Random Allocation; D015424:Reperfusion; D013552:Swine; D014662:Vasoconstrictor Agents / Q000627:therapeutic use*
chemical_list: D014662:Vasoconstrictor Agents; D001127:Arginine Vasopressin; D010656:Phenylephrine; D010100:Oxygen