title: Hyperoxic resuscitation improves survival but worsens neurologic outcome in a rat polytrauma model of traumatic brain injury plus hemorrhagic shock.
abstract: BACKGROUND
  Many traumatic brain injury (TBI) patients experience additional injuries, including those that result in hemorrhagic shock (HS). Interactions between HS and TBI can include reduced brain O2 delivery, resulting in partial cerebral ischemia and worse neurologic outcome. This study tested the hypothesis that inspiration of 100% O2 during resuscitation following TBI and HS improves survival, reduces brain lesion volume, and improves neurologic outcome compared with resuscitation in the absence of supplemental O2.
  
  
  METHODS
  The adult male rat polytrauma model consisted of controlled cortical impact-induced TBI followed by 30 minutes of HS (mean arterial pressure, 35-40 mm Hg) induced by blood withdrawal. The HS phase was followed by a 1-hour "prehospital" Hextend fluid resuscitation phase and then a 1-hour "hospital phase" when shed blood was reinfused. Rats were randomized on the day of surgery to three groups with 10 per group: sham, polytrauma normoxic, and polytrauma hyperoxic. Normoxic animals inspired room air, and hyperoxic animals inspired 100% O2 during both resuscitation phases. Neurobehavioral tests were conducted weekly until the rats were perfused with fixative at 30 days after injury. Brain sections were stained with Fluoro Jade B and used for quantification of contusion, penumbral, and healthy cortical volumes.
  
  
  RESULTS
  Survival was greater following hyperoxic compared with normoxic resuscitation. Composite neuroscores obtained at 2 weeks to 4 weeks following hyperoxic resuscitation were lower than those of shams. Balance beam foot faults measured at 2 weeks after injury were greater following hyperoxic resuscitation compared with normoxic resuscitation and those of shams. There was no significant difference in cerebrocortical pathology between the normoxic and hyperoxic polytrauma groups.
  
  
  CONCLUSIONS
  The survival of rats following controlled cortical impact plus HS was greater following hyperoxic resuscitation. In contrast, neurologic outcomes were better following normoxic resuscitation.
authors.affiliation: From the Department of Anesthesiology (J.L.P., D.S., Y.P., J.V., R.E.R., G.F.), Center for Shock, Trauma, and Anesthesiology Research (J.L.P., D.S., Y.P., J.V., R.E.R., G.F.), Department of Emergency Medicine (R.E.R.), and Department of Anatomy and Neuroscience (A.P.), University of Maryland School of Medicine, Baltimore, Maryland.
authors.forename: Julie L
authors.initials: JL
authors.lastname: Proctor
authors.forename: Dominique
authors.initials: D
authors.lastname: Scutella
authors.forename: Yan
authors.initials: Y
authors.lastname: Pan
authors.forename: Joshua
authors.initials: J
authors.lastname: Vaughan
authors.forename: Robert E
authors.initials: RE
authors.lastname: Rosenthal
authors.forename: Adam
authors.initials: A
authors.lastname: Puche
authors.forename: Gary
authors.initials: G
authors.lastname: Fiskum
mesh_terms: D000818:Animals; D001930:Brain Injuries / Q000503:physiopathology / Q000628:therapy*; D004195:Disease Models, Animal; D008297:Male; D009104:Multiple Trauma / Q000503:physiopathology / Q000628:therapy; D010102:Oxygen Inhalation Therapy; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012151:Resuscitation / Q000379:methods*; D012771:Shock, Hemorrhagic / Q000503:physiopathology / Q000628:therapy*; D015996:Survival Rate