title: Association between hyperoxia and mortality after stroke: a multicenter cohort study.
abstract: OBJECTIVE
  To test the hypothesis that hyperoxia was associated with higher in-hospital mortality in ventilated stroke patients admitted to the ICU.
  
  
  METHODS
  Retrospective multicenter cohort study.
  
  
  METHODS
  Primary admissions of ventilated stroke patients with acute ischemic stroke, subarachnoid hemorrhage, and intracerebral hemorrhage who had arterial blood gases within 24 hours of admission to the ICU at 84 U.S. ICUs between 2003 and 2008. Patients were divided into three exposure groups: hyperoxia was defined as PaO2 ≥ 300 mm Hg (39.99 kPa), hypoxia as any PaO2<60 mm Hg (7.99 kPa) or PaO2/FiO2 ratio ≤ 300, and normoxia, not defined as hyperoxia or hypoxia. The primary outcome was in-hospital mortality.
  
  
  METHODS
  Two thousand eight hundred ninety-four patients.
  
  
  METHODS
  Patients were divided into three exposure groups: hyperoxia was defined as PaO2 more than or equal to 300 mm Hg (39.99 kPa), hypoxia as any PaO2 less than 60 mm Hg (7.99 kPa) or PaO2/FIO2 ratio less than or equal to 300, and normoxia, not defined as hyperoxia or hypoxia. The primary outcome was in-hospital mortality.
  
  
  METHODS
  Exposure to hyperoxia.
  
  
  RESULTS
  Over the 5-year period, we identified 554 ventilated patients with acute ischemic stroke (19%), 936 ventilated patients with subarachnoid hemorrhage (32%), and 1,404 ventilated patients with intracerebral hemorrhage (49%) of whom 1,084 (38%) were normoxic, 1,316 (46%) were hypoxic, and 450 (16%) were hyperoxic. Mortality was higher in the hyperoxia group as compared with normoxia (crude odds ratio 1.7 [95% CI 1.3-2.1]; p < 0.0001) and hypoxia groups (crude odds ratio, 1.3 [95% CI, 1.1-1.7]; p < 0.01). In a multivariable analysis adjusted for admission diagnosis, other potential confounders, the probability of being exposed to hyperoxia, and hospital-specific effects, exposure to hyperoxia was independently associated with in-hospital mortality (adjusted odds ratio, 1.2 [95% CI, 1.04-1.5]).
  
  
  CONCLUSIONS
  In ventilated stroke patients admitted to the ICU, arterial hyperoxia was independently associated with in-hospital death as compared with either normoxia or hypoxia. These data underscore the need for studies of controlled reoxygenation in ventilated critically ill stroke populations. In the absence of results from clinical trials, unnecessary oxygen delivery should be avoided in ventilated stroke patients.
authors.affiliation: 1Department of Neurology, Thomas Jefferson University, Philadelphia, PA. 2Division of Critical Care and Neurotrauma, Department of Neurosurgery, Thomas Jefferson University, Philadelphia, PA. 3Division of Biostatistics, Rothman Institute of Thomas Jefferson University, Philadelphia, PA. 4Department of Medicine, Thomas Jefferson University, Philadelphia, PA. 5Division of Cerebrovascular Diseases, Thomas Jefferson University, Philadelphia, PA.
authors.forename: Fred
authors.initials: F
authors.lastname: Rincon
authors.forename: Joon
authors.initials: J
authors.lastname: Kang
authors.forename: Mitchell
authors.initials: M
authors.lastname: Maltenfort
authors.forename: Matthew
authors.initials: M
authors.lastname: Vibbert
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Urtecho
authors.forename: M Kamran
authors.initials: MK
authors.lastname: Athar
authors.forename: Jack
authors.initials: J
authors.lastname: Jallo
authors.forename: Carissa C
authors.initials: CC
authors.lastname: Pineda
authors.forename: Diana
authors.initials: D
authors.lastname: Tzeng
authors.forename: William
authors.initials: W
authors.lastname: McBride
authors.forename: Rodney
authors.initials: R
authors.lastname: Bell
mesh_terms: D015331:Cohort Studies; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D018496:Hyperoxia / Q000209:etiology* / Q000401:mortality*; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D020521:Stroke / Q000150:complications* / Q000401:mortality*