title: Failure of non-invasive ventilation in patients with acute lung injury: observational cohort study.
abstract: BACKGROUND
  The role of non-invasive positive pressure ventilation (NIPPV) in the treatment of acute lung injury (ALI) is controversial. We sought to assess the outcome of ALI that was initially treated with NIPPV and to identify specific risk factors for NIPPV failure.
  
  
  METHODS
  In this observational cohort study at the two intensive care units of a tertiary center, we identified consecutive patients with ALI who were initially treated with NIPPV. Data on demographics, APACHE III scores, degree of hypoxemia, ALI risk factors and NIPPV respiratory parameters were recorded. Univariate and multivariate regression analyses were performed to identify risk factors for NIPPV failure.
  
  
  RESULTS
  Of 79 consecutive patients who met the inclusion criteria, 23 were excluded because of a do not resuscitate order and two did not give research authorization. Of the remaining 54 patients, 38 (70.3%) failed NIPPV, among them all 19 patients with shock. In a stepwise logistic regression restricted to patients without shock, metabolic acidosis (odds ratio 1.27, 95% confidence interval (CI) 1.03 to 0.07 per unit of base deficit) and severe hypoxemia (odds ratio 1.03, 95%CI 1.01 to 1.05 per unit decrease in ratio of arterial partial pressure of O2 and inspired O2 concentration--PaO2/FiO2) predicted NIPPV failure. In patients who failed NIPPV, the observed mortality was higher than APACHE predicted mortality (68% versus 39%, p < 0.01).
  
  
  CONCLUSIONS
  NIPPV should be tried very cautiously or not at all in patients with ALI who have shock, metabolic acidosis or profound hypoxemia.
authors.affiliation: Department of Internal Medicine, Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, Minnesota USA.
authors.forename: Sameer
authors.initials: S
authors.lastname: Rana
authors.forename: Hussam
authors.initials: H
authors.lastname: Jenad
authors.forename: Peter C
authors.initials: PC
authors.lastname: Gay
authors.forename: Curtis F
authors.initials: CF
authors.lastname: Buck
authors.forename: Rolf D
authors.initials: RD
authors.lastname: Hubmayr
authors.forename: Ognjen
authors.initials: O
authors.lastname: Gajic
mesh_terms: D000208:Acute Disease; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011175:Positive-Pressure Respiration; D011446:Prospective Studies; D012131:Respiratory Insufficiency / Q000401:mortality / Q000503:physiopathology / Q000628:therapy*; D012307:Risk Factors