title: Radiographic lung density assessed by computed tomography is associated with extravascular lung water content.
abstract: BACKGROUND
  We hypothesized that in acute lung injury (ALI), the volume of pulmonary tissue with aqueous density, as determined by spiral computed tomography (CT), is associated with extravascular lung water content. Our aim was to compare tissue volume index, as assessed by CT, before and after oleic acid-induced ALI, with extravascular lung water indexes (EVLWI), determined with single transpulmonary thermodilution (EVLWI(STD)), thermal-dye dilution (EVLWI(TDD)), and postmortem gravimetry (EVLWI(G)).
  
  
  METHODS
  Seven instrumented sheep received an intravenous infusion of oleic acid 0.08 ml/kg (OA group) and four animals had vehicle only (Control group). The day before, and immediately after the experiment, sheep were anesthetized to undergo quantitative CT examinations during a short breath hold. Hemodynamics, oxygenation, EVLWI(STD), and EVLW(TDD) were registered. Linear regression analysis was used to assess the relationships between EVLWI(STD), EVLW(TDD), EVLWI(G), and lung tissue volume index (TVI(CT)) determined with CT.
  
  
  RESULTS
  In the OA group, total lung volume increased compared with Controls. Poorly and non-aerated lung volumes increased a 3.6- and 4.9-fold, respectively, and TVI(CT) almost doubled. EVLWI(STD), EVLWI(TDD), and TVI(CT) were associated significantly with EVLWI(G) (r=0.85, 0.90, and 0.88, respectively; P<0.001). TVI(CT) deviated from the reference EVLWI(G) values to the greatest extent with a mean bias +/- 2SD of 4.0 +/- 6.0 ml/kg.
  
  
  CONCLUSIONS
  In ovine oleic acid-induced ALI, lung tissue volume, as assessed by quantitative CT, is in close agreement with EVLWI, as determined by indicator dilution methods and postmortem gravimetry, but overestimates lung fluid content.
authors.affiliation: Department of Anaesthesiology, Institute of Clinical Medicine, Faculty of Health Sciences, University of Tromsø and University Hospital of North Norway, Tromsø, Norway.
authors.forename: V V
authors.initials: VV
authors.lastname: Kuzkov
authors.forename: E V
authors.initials: EV
authors.lastname: Suborov
authors.forename: M Y
authors.initials: MY
authors.lastname: Kirov
authors.forename: K
authors.initials: K
authors.lastname: Waerhaug
authors.forename: R
authors.initials: R
authors.lastname: Mortensen
authors.forename: V N
authors.initials: VN
authors.lastname: Kuklin
authors.forename: K C
authors.initials: KC
authors.lastname: Nordhus
authors.forename: L J
authors.initials: LJ
authors.lastname: Bjertnaes
mesh_terms: D055371:Acute Lung Injury / Q000139:chemically induced / Q000000981:diagnostic imaging; D000465:Algorithms; D000818:Animals; D004395:Dye Dilution Technique; D015633:Extravascular Lung Water / Q000000981:diagnostic imaging*; D006439:Hemodynamics / Q000502:physiology; D008168:Lung / Q000000981:diagnostic imaging*; D019301:Oleic Acid; D011659:Pulmonary Gas Exchange / Q000502:physiology; D015203:Reproducibility of Results; D012128:Respiratory Distress Syndrome; D012756:Sheep; D013815:Thermodilution; D014057:Tomography, X-Ray Computed
chemical_list: D019301:Oleic Acid