title: Electrical impedance tomography in the assessment of extravascular lung water in noncardiogenic acute respiratory failure.
abstract: OBJECTIVE
  To establish the value of electrical impedance tomography (EIT) in assessing pulmonary edema in noncardiogenic acute respiratory failure (ARF), as compared to the thermal dye double indicator dilution technique (TDD).
  
  
  METHODS
  Prospective clinical study.
  
  
  METHODS
  ICU of a general hospital.
  
  
  METHODS
  Fourteen ARF patients.
  
  
  METHODS
  In order to use the TDD to determine the amount of extravascular lung water (EVLW), a fiberoptic catheter was placed in the femoral artery.
  
  
  RESULTS
  Fourteen consecutive ARF patients receiving mechanical ventilation were measured by EIT and TDD. EIT visualizes the impedance changes caused by the ventilation in two-dimensional image planes. An impedance ratio (IR) of the ventilation-induced impedance changes of a posterior and an anterior part of the lungs was used to indicate the amount of EVLW. For the 29 measurements in 14 patients, a significant correlation between EIT and TDD (r = 0. 85; p < 0.001) was found. The EIT reproducibility was good. The diagnostic value of the method was tested by receiver operator characteristic analysis, with 10 mL/kg of EVLW considered as the upper limit of normal. At a cutoff level of the IR of 0.64, the IR had a sensitivity of 93%, a specificity of 87%, and a positive predictive value of 87% for a supranormal amount of EVLW. Follow-up measurements were performed in 11 patients. A significant correlation was found between the changes in EVLW measured with EIT and TDD (r = 0.85; p < 0.005).
  
  
  CONCLUSIONS
  We conclude that EIT is a noninvasive technique for reasonably estimating the amount of EVLW in noncardiogenic ARF.
authors.affiliation: Department of Pulmonary Medicine, Hospital Centre Apeldorn, The Netherlands.
authors.forename: P W
authors.initials: PW
authors.lastname: Kunst
authors.forename: A
authors.initials: A
authors.lastname: Vonk Noordegraaf
authors.forename: E
authors.initials: E
authors.lastname: Raaijmakers
authors.forename: J
authors.initials: J
authors.lastname: Bakker
authors.forename: A B
authors.initials: AB
authors.lastname: Groeneveld
authors.forename: P E
authors.initials: PE
authors.lastname: Postmus
authors.forename: P M
authors.initials: PM
authors.lastname: de Vries
mesh_terms: D000208:Acute Disease; D000328:Adult; D004395:Dye Dilution Technique; D017097:Electric Impedance; D015633:Extravascular Lung Water; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011175:Positive-Pressure Respiration; D011446:Prospective Studies; D012372:ROC Curve; D012131:Respiratory Insufficiency; D012680:Sensitivity and Specificity