title: Critical care ultrasonography differentiates ARDS, pulmonary edema, and other causes in the early course of acute hypoxemic respiratory failure.
abstract: BACKGROUND
  Pathogenic causes of acute hypoxemic respiratory failure (AHRF) can be difficult to identify at early clinical presentation. We evaluated the diagnostic utility of combined cardiac and thoracic critical care ultrasonography (CCUS).
  
  
  METHODS
  Adult patients in the ICU were prospectively enrolled from January through September 2010 with a Pao2/Fio2 ratio < 300 on arterial blood gas (ABG) analysis within 6 h of a new hypoxemic event or the ICU admission. Focused cardiac and thoracic CCUS was conducted within 6 h of ABG testing. Causes of AHRF were categorized into cardiogenic pulmonary edema (CPE), ARDS, and miscellaneous causes after reviewing the hospitalization course in electronic medical records.
  
  
  RESULTS
  One hundred thirty-four patients were enrolled (median Pao2/Fio2 ratio, 191; interquartile range, 122-253). Fifty-nine patients (44%) received a diagnosis of CPE; 42 (31%), ARDS; and 33 (25%), miscellaneous cause. Analysis of CCUS findings showed that a low B-line ratio (proportion of chest zones with positive B-lines relative to all zones examined) was predictive of miscellaneous cause vs CPE or ARDS (receiver operating characteristic area under the curve [AUC], 0.82; 95% CI, 0.75-0.88). For further differentiation of CPE from ARDS, left-sided pleural effusion (> 20 mm), moderately or severely decreased left ventricular function, and a large inferior vena cava minimal diameter (> 23 mm) were predictive of CPE (AUC, 0.79; 95% CI, 0.70-0.87).
  
  
  CONCLUSIONS
  Combined cardiac and thoracic CCUS assists in early bedside differential diagnosis of ARDS, CPE, and other causes of AHRF.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, MN. Electronic address: sekiguchi.hiroshi@mayo.edu.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sekiguchi
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, MN; Division of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, MN.
authors.forename: Louis A
authors.initials: LA
authors.lastname: Schenck
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, MN.
authors.forename: Ryohei
authors.initials: R
authors.lastname: Horie
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, MN.
authors.forename: Jun
authors.initials: J
authors.lastname: Suzuki
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, MN.
authors.forename: Edwin H
authors.initials: EH
authors.lastname: Lee
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, MN.
authors.forename: Brendan P
authors.initials: BP
authors.lastname: McMenomy
authors.affiliation: Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN.
authors.forename: Tien-En
authors.initials: TE
authors.lastname: Chen
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, MN.
authors.forename: Alexander
authors.initials: A
authors.lastname: Lekah
authors.affiliation: Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN.
authors.forename: Sunil V
authors.initials: SV
authors.lastname: Mankad
authors.affiliation: Division of Health Care Policy and Research, Mayo Clinic, Rochester, MN; Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, MN.
authors.forename: Ognjen
authors.initials: O
authors.lastname: Gajic
mesh_terms: D000208:Acute Disease; D000328:Adult; D001784:Blood Gas Analysis; D003422:Critical Care / Q000379:methods*; D003937:Diagnosis, Differential; D004867:Equipment Design; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D000860:Hypoxia / Q000150:complications* / Q000175:diagnosis; D008297:Male; D011446:Prospective Studies; D011654:Pulmonary Edema / Q000000981:diagnostic imaging* / Q000209:etiology; D012128:Respiratory Distress Syndrome / Q000000981:diagnostic imaging* / Q000209:etiology; D014463:Ultrasonography / Q000295:instrumentation* / Q000379:methods