title: Practice of excessive F(IO(2)) and effect on pulmonary outcomes in mechanically ventilated patients with acute lung injury.
abstract: BACKGROUND
  Optimal titration of inspired oxygen is important to prevent hyperoxia in mechanically ventilated patients in ICUs. There is mounting evidence of the deleterious effects of hyperoxia; however, there is a paucity of data about F(IO(2)) practice and oxygen  exposure among patients in ICUs. We therefore sought to assess excessive F(IO(2)) exposure in mechanically ventilated patients with acute lung injury and to evaluate the effect on pulmonary outcomes.
  
  
  METHODS
  From a database of ICU patients with acute lung injury identified  by prospective electronic medical record screening, we identified those who underwent invasive mechanical ventilation for > 48 hours from January 1 to December 31, 2008. Ventilator settings, including F(IO(2)) and corresponding S(pO(2)), were collected  from the electronic medical record at 15-min intervals for the first 48 hours. Excessive F(IO(2)) was defined as F(IO(2)) > 0.5 despite S(pO(2)) > 92%. The association between the duration of excessive exposure and pulmonary outcomes  was assessed by change in oxygenation index from baseline to 48 hours and was analyzed by univariate and multivariate linear regression analysis.
  
  
  RESULTS
  Of 210 patients who met the inclusion criteria, 155 (74%) were exposed to excessive F(IO(2)) for a median duration of  17 hours (interquartile range 7.5-33 h). Prolonged exposure to excessive F(IO(2)) correlated with worse oxygenation index at 48 hours in a dose-response manner (P < .001.). Both exposure to higher F(IO(2)) and longer duration of exposure  were associated with worsening oxygenation index at 48 hours (P < .001), more days on mechanical ventilation, longer ICU stay, and longer hospital stay (P = .004). No mortality difference was noted.
  
  
  CONCLUSIONS
  Excessive oxygen supplementation is common in mechanically ventilated  patients with ALI and may be associated with worsening lung function.
authors.affiliation: Mayo Epidemiology and Translational Research in Intensive Care program, Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, MN 55905, USA. rachmale.sonal@mayo.edu
authors.forename: Sonal
authors.initials: S
authors.lastname: Rachmale
authors.forename: Guangxi
authors.initials: G
authors.lastname: Li
authors.forename: Gregory
authors.initials: G
authors.lastname: Wilson
authors.forename: Michael
authors.initials: M
authors.lastname: Malinchoc
authors.forename: Ognjen
authors.initials: O
authors.lastname: Gajic
mesh_terms: D055371:Acute Lung Injury / Q000503:physiopathology / Q000628:therapy*; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D010102:Oxygen Inhalation Therapy / Q000009:adverse effects*; D012121:Respiration, Artificial / Q000379:methods*; D018709:Statistics, Nonparametric; D016896:Treatment Outcome