title: Quantitative diagnosis of diffuse alveolar damage using extravascular lung water.
abstract: OBJECTIVE
  Acute respiratory distress syndrome is characterized by diffuse alveolar damage and increased extravascular lung water levels. However, there is no threshold extravascular lung water level that can indicate diffuse alveolar damage in lungs. We aimed to determine the threshold extravascular lung water level that discriminates between normal lungs and lungs affected with diffuse alveolar damage.
  
  
  METHODS
  A retrospective analysis of normal lungs and lungs affected with diffuse alveolar damage was performed.
  
  
  METHODS
  Normal lung cases were taken from published data. Lung cases with diffuse alveolar damage were taken from a nationwide autopsy database. All cases of autopsy followed hospital deaths in Japan from more than 800 hospitals between 2004 and 2009; complete autopsies with histopathologic examinations were performed by board-certified pathologists authorized by the Japanese Society of Pathology.
  
  
  METHODS
  Normal lungs: 534; lungs with diffuse alveolar damage: 1,688.
  
  
  METHODS
  We compared the postmortem weights of both lungs between the two groups. These lung weights were converted to extravascular lung water values using a validated equation. Finally, the extravascular lung water value that indicated diffuse alveolar damage was estimated using receiver operating characteristic analysis.
  
  
  RESULTS
  The extravascular lung water values of the lungs showing diffuse alveolar damage were approximately two-fold higher than those of normal lungs (normal group, 7.3±2.8 mL/kg vs diffuse alveolar damage group 13.7±4.5 mL/kg; p<0.001). An extravascular lung water level of 9.8 mL/kg allowed the diagnosis of diffuse alveolar damage to be established with a sensitivity of 81.3% and a specificity of 81.2% (area under the curve, 0.90; 95% CI, 0.88-0.91). An extravascular lung water level of 14.6 mL/kg represented a 99% positive predictive value.
  
  
  CONCLUSIONS
  This study may provide the first validated quantitative bedside diagnostic tool for diffuse alveolar damage. Extravascular lung water may allow the detection of diffuse alveolar damage and may support the clinical diagnosis of acute respiratory distress syndrome. The best extravascular lung water cut-off value to discriminate between normal lungs and lungs with diffuse alveolar damage is around 10 mL/kg.
authors.affiliation: Department of Emergency and Critical Care Medicine, Nippon Medical School, Tokyo, Japan. t-tagami@nms.ac.jp
authors.forename: Takashi
authors.initials: T
authors.lastname: Tagami
authors.forename: Motoji
authors.initials: M
authors.lastname: Sawabe
authors.forename: Shigeki
authors.initials: S
authors.lastname: Kushimoto
authors.forename: Paul E
authors.initials: PE
authors.lastname: Marik
authors.forename: Makiko N
authors.initials: MN
authors.lastname: Mieno
authors.forename: Takanori
authors.initials: T
authors.lastname: Kawaguchi
authors.forename: Takashi
authors.initials: T
authors.lastname: Kusakabe
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Tosa
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yokota
authors.forename: Yuh
authors.initials: Y
authors.lastname: Fukuda
mesh_terms: D055371:Acute Lung Injury; D001344:Autopsy; D016001:Confidence Intervals; D016208:Databases, Factual; D015633:Extravascular Lung Water; D005260:Female; D006801:Humans; D007564:Japan; D008297:Male; D011650:Pulmonary Alveoli / Q000473:pathology*; D012372:ROC Curve; D012128:Respiratory Distress Syndrome / Q000175:diagnosis*; D012189:Retrospective Studies; D012720:Severity of Illness Index