title: SpO2/FiO2 ratio on hospital admission is an indicator of early acute respiratory distress syndrome development among patients at risk.
abstract: OBJECTIVE
  Oxygen saturation to fraction of inspired oxygen ratio (SpO(2)/FiO(2)) has been validated as a surrogate marker for partial pressure of oxygen to fraction of inspired oxygen ratio among mechanically ventilated patients with acute respiratory distress syndrome (ARDS). The validity of SpO(2)/FiO(2) measurements in predicting ARDS has not been studied. Recently, a Lung Injury Prediction Score (LIPS) has been developed to help identify patients at risk of developing ARDS.
  
  
  METHODS
  This was a secondary analysis of the LIPS-1 cohort. A multivariate logistic regression included all established variables for LIPS, Acute Physiology and Chronic Health Evaluation 2, age, and comorbid conditions that could affect SpO(2)/FiO(2). The primary outcome was development of ARDS in the hospital. The secondary outcomes included hospital mortality, hospital day of ARDS development, and hospital day of death.
  
  
  RESULTS
  Of the 5584 patients, we evaluated all 4646 with recorded SpO(2)/FiO(2) values. Median SpO(2)/FiO(2) in those who did and did not develop ARDS was 254 (100, 438) and 452 (329, 467), respectively. There was a significant association between SpO(2)/FiO(2) and ARDS (P ≤ .001). The SpO(2)/FiO(2) was found to be an independent predictor of ARDS in a "dose-dependent" manner; for SpO(2)/FiO(2) < 100--odds ratios (OR) 2.49 (1.69-3.64, P < .001), for SpO(2)/FiO(2) 100 < 200--OR 1.75 (1.16-2.58, P = .007), and for SpO(2)/FiO(2) 200 < 300--OR 1.62 (1.06-2.42, P = .025). The discriminatory characteristics of the multivariable model and SpO2/FiO2 as a single variable demonstrated area under the curve (AUC) of 0.81 and AUC of 0.74, respectively.
  
  
  CONCLUSIONS
  The SpO2/FiO2, measured within the first 6 hours after hospital admission, is an independent indicator of ARDS development among patients at risk.
authors.affiliation: Pulmonary and Critical Care Medicine, Mayo Clinic, Jacksonville, FL, USA festic.emir@mayo.edu.
authors.forename: Emir
authors.initials: E
authors.lastname: Festic
authors.affiliation: Critical Care Research, Mayo Clinic, Jacksonville, FL, USA.
authors.forename: Vikas
authors.initials: V
authors.lastname: Bansal
authors.affiliation: Anesthesiology and Critical Care, Mayo Clinic, Rochester, MN, USA.
authors.forename: Daryl J
authors.initials: DJ
authors.lastname: Kor
authors.affiliation: Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, MN, USA.
authors.forename: Ognjen
authors.initials: O
authors.lastname: Gajic
mesh_terms: D055371:Acute Lung Injury / Q000175:diagnosis* / Q000401:mortality; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D042241:Early Diagnosis; D005260:Female; D006305:Health Status Indicators; D017052:Hospital Mortality; D006760:Hospitalization; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D010100:Oxygen; D010313:Partial Pressure; D011175:Positive-Pressure Respiration / Q000706:statistics & numerical data*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results; D012128:Respiratory Distress Syndrome / Q000175:diagnosis* / Q000401:mortality; D012307:Risk Factors
chemical_list: D010100:Oxygen
keywords: ARDS; admission; oxygenation; prediction