title: Brain hypoxia is associated with short-term outcome after severe traumatic brain injury independently of intracranial hypertension and low cerebral perfusion pressure.
abstract: BACKGROUND
  Brain hypoxia (BH) can aggravate outcome after severe traumatic brain injury (TBI). Whether BH or reduced brain oxygen (Pbto(2)) is an independent outcome predictor or a marker of disease severity is not fully elucidated.
  
  
  OBJECTIVE
  To analyze the relationship between Pbto(2), intracranial pressure (ICP), and cerebral perfusion pressure (CPP) and to examine whether BH correlates with worse outcome independently of ICP and CPP.
  
  
  METHODS
  We studied 103 patients monitored with ICP and Pbto(2) for > 24 hours. Durations of BH (Pbto(2) < 15 mm Hg), ICP > 20 mm Hg, and CPP < 60 mm Hg were calculated with linear interpolation, and their associations with outcome within 30 days were analyzed.
  
  
  RESULTS
  Duration of BH was longer in patients with unfavorable (Glasgow Outcome Scale score, 1-3) than in those with favorable (Glasgow Outcome Scale, 4-5) outcome (8.3 ± 15.9 vs 1.7 ± 3.7 hours; P < .01). In patients with intracranial hypertension, those with BH had fewer favorable outcomes (46%) than those without (81%; P < .01); similarly, patients with low CPP and BH were less likely to have favorable outcome than those with low CPP but normal Pbto(2) (39% vs 83%; P < .01). After ICP, CPP, age, Glasgow Coma Scale score, Marshall computed tomography grade, and Acute Physiology and Chronic Health Evaluation II score were controlled for, BH was independently associated with poor prognosis (adjusted odds ratio for favorable outcome, 0.89 per hour of BH; 95% confidence interval, 0.79-0.99; P = .04).
  
  
  CONCLUSIONS
  Brain hypoxia is associated with poor short-term outcome after severe traumatic brain injury independently of elevated ICP, low CPP, and injury severity. Pbto(2) may be an important therapeutic target after severe traumatic brain injury.
authors.affiliation: Department of Neurosurgery, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania 19107, USA.
authors.forename: Mauro
authors.initials: M
authors.lastname: Oddo
authors.forename: Joshua M
authors.initials: JM
authors.lastname: Levine
authors.forename: Larami
authors.initials: L
authors.lastname: Mackenzie
authors.forename: Suzanne
authors.initials: S
authors.lastname: Frangos
authors.forename: François
authors.initials: F
authors.lastname: Feihl
authors.forename: Scott E
authors.initials: SE
authors.lastname: Kasner
authors.forename: Michael
authors.initials: M
authors.lastname: Katsnelson
authors.forename: Bryan
authors.initials: B
authors.lastname: Pukenas
authors.forename: Eileen
authors.initials: E
authors.lastname: Macmurtrie
authors.forename: Eileen
authors.initials: E
authors.lastname: Maloney-Wilensky
authors.forename: W Andrew
authors.initials: WA
authors.lastname: Kofke
authors.forename: Peter D
authors.initials: PD
authors.lastname: LeRoux
mesh_terms: D000328:Adult; D001930:Brain Injuries / Q000150:complications* / Q000401:mortality; D002560:Cerebrovascular Circulation / Q000502:physiology*; D002561:Cerebrovascular Disorders / Q000209:etiology* / Q000401:mortality; D005260:Female; D006801:Humans; D007022:Hypotension / Q000209:etiology* / Q000401:mortality; D002534:Hypoxia, Brain / Q000209:etiology* / Q000401:mortality; D007427:Intracranial Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012189:Retrospective Studies; D013997:Time Factors; D055815:Young Adult