title: Inferior vena cava assessment in the bedside diagnosis of acute heart failure.
abstract: OBJECTIVE
  The objective of this study was to determine the test characteristics of the caval index and caval-aortic ratio in predicting the diagnosis of acute heart failure in patients with undifferentiated dyspnea in the emergency department (ED).
  
  
  METHODS
  This prospective observational study was performed at an urban ED that enrolled patients, 50 years or older, with acute dyspnea. A sonographic caval index was calculated as the percentage decrease in the inferior vena cava (IVC) diameter during respiration. A caval-aortic ratio was defined by the maximum IVC diameter divided by the aortic diameter. The sensitivity, specificity, and likelihood ratios of these measurements associated with heart failure were estimated.
  
  
  RESULTS
  Eighty-nine patients were enrolled in the study with a mean age of 68 years. A caval index of less than 33% had 80% sensitivity (95% confidence interval [CI], 63%-91%) and 81% specificity (95% CI, 68%-90%) in diagnosing acute heart failure, whereas an index of less than 15% had a 37% sensitivity (95% CI, 22%-55%) and 96% specificity (95% CI, 86%-99%). The sensitivity of a caval-aortic ratio of more than 1.2 was 33% (95% CI, 18%-52%) and the specificity was 96% (95% CI, 86%-99%). Positive likelihood ratios were 10 for a caval index of less than 15%, 4.3 for an index of less than 33%, and 8.3 for a caval-aortic ratio of more than 1.2.
  
  
  CONCLUSIONS
  Bedside assessments of the caval index or caval-aortic ratio may be useful clinical adjuncts in establishing the diagnosis of acute heart failure in patients with undifferentiated dyspnea.
authors.affiliation: Department of Emergency Medicine, Henry Ford Hospital, Detroit, MI 48202, USA. jmiller6@hfhs.org
authors.forename: Joseph B
authors.initials: JB
authors.lastname: Miller
authors.forename: Ayan
authors.initials: A
authors.lastname: Sen
authors.forename: Seth R
authors.initials: SR
authors.lastname: Strote
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Hegg
authors.forename: Sarah
authors.initials: S
authors.lastname: Farris
authors.forename: Abigail
authors.initials: A
authors.lastname: Brackney
authors.forename: David
authors.initials: D
authors.lastname: Amponsah
authors.forename: Usamah
authors.initials: U
authors.lastname: Mossallam
mesh_terms: D000368:Aged; D003937:Diagnosis, Differential; D004417:Dyspnea / Q000000981:diagnostic imaging / Q000473:pathology; D004636:Emergency Service, Hospital; D005260:Female; D006333:Heart Failure / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D008297:Male; D009929:Organ Size; D019095:Point-of-Care Systems; D011446:Prospective Studies; D012372:ROC Curve; D012680:Sensitivity and Specificity; D014463:Ultrasonography; D014682:Vena Cava, Inferior / Q000000981:diagnostic imaging* / Q000473:pathology