title: The use of the radiographic appearance of the azygos vein to assess volume status in trauma patients.
abstract: BACKGROUND
  The assessment of hypovolemia in victims of trauma is a critical aspect of resuscitation and care in the initial presentation of a patient. This study attempted to validate the use of the appearance of the azygos vein (AV) on initial chest radiographs as a parameter that may add to this initial assessment.
  
  
  METHODS
  The design involved a blinded independent assessment of serial chest radiographs from consecutive trauma cases from January 21, 2008, until September 13, 2008, by a trained Radiologist and a Trauma Team Leader (TTL) and then comparing this assessment to mean arterial pressure (MAP) and heart rate estimates of volume status in serial severe trauma patients. This is an insensitive but specific measure of volume status.
  
  
  RESULTS
  In this population with high prevalence of hypovolemia, the presence of an AV ≤ 0.5 cm yielded a sensitivity of 4.9% and 9.8% for the TTL and Radiologist, respectively, in patients with a mean arterial pressure <70 and heart rate >100. The specificity was 98.8% and 91.6%, which translates into a positive likelihood ratio of 4.08 and 1.17 for the TTL and Radiologist, respectively. The Kappa score for agreement between the two readers was 0.4.
  
  
  CONCLUSIONS
  When a small AV can be seen by the TTL, it may be a useful adjunct to the assessment of volume status.
authors.affiliation: Department of Medicine, University of Alberta, Edmonton, Alberta, Canada. neil.gibson@ualberta.ca
authors.forename: Neil E
authors.initials: NE
authors.lastname: Gibson
authors.forename: Christine R
authors.initials: CR
authors.lastname: Stehman
authors.forename: Rennae
authors.initials: R
authors.lastname: Thiessen
authors.forename: Katherine J
authors.initials: KJ
authors.lastname: Gibson
mesh_terms: D000328:Adult; D000368:Aged; D001401:Azygos Vein / Q000000981:diagnostic imaging*; D002170:Canada / Q000453:epidemiology; D005260:Female; D006801:Humans; D020896:Hypovolemia / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000209:etiology; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D015995:Prevalence; D011379:Prognosis; D012372:ROC Curve; D013902:Radiography, Thoracic / Q000379:methods*; D012189:Retrospective Studies; D014949:Wounds, Nonpenetrating / Q000150:complications / Q000000981:diagnostic imaging*; D055815:Young Adult