title: Electrical impedance tomography (EIT) for quantification of pulmonary edema in acute lung injury.
abstract: BACKGROUND
  Assessment of pulmonary edema is a key factor in monitoring and guidance of therapy in critically ill patients. To date, methods available at the bedside for estimating the physiologic correlate of pulmonary edema, extravascular lung water, often are unreliable or require invasive measurements. The aim of the present study was to develop a novel approach to reliably assess extravascular lung water by making use of the functional imaging capabilities of electrical impedance tomography.
  
  
  METHODS
  Thirty domestic pigs were anesthetized and randomized to three different groups. Group 1 was a sham group with no lung injury. Group 2 had acute lung injury induced by saline lavage. Group 3 had vascular lung injury induced by intravenous injection of oleic acid. A novel, noninvasive technique using changes in thoracic electrical impedance with lateral body rotation was used to measure a new metric, the lung water ratioEIT, which reflects total extravascular lung water. The lung water ratioEIT was compared with postmortem gravimetric lung water analysis and transcardiopulmonary thermodilution measurements.
  
  
  RESULTS
  A significant correlation was found between extravascular lung water as measured by postmortem gravimetric analysis and electrical impedance tomography (r = 0.80; p < 0.05). Significant changes after lung injury were found in groups 2 and 3 in extravascular lung water derived from transcardiopulmonary thermodilution as well as in measurements derived by lung water ratioEIT.
  
  
  CONCLUSIONS
  Extravascular lung water could be determined noninvasively by assessing characteristic changes observed on electrical impedance tomograms during lateral body rotation. The novel lung water ratioEIT holds promise to become a noninvasive bedside measure of pulmonary edema.
authors.affiliation: Department of Anaesthesiology, Center for Anaesthesiology and Intensive Care Medicine, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, D-20246, Hamburg, Germany. c.trepte@uke.de.
authors.forename: Constantin J C
authors.initials: CJ
authors.lastname: Trepte
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Medicine, Center for Intensive Care Research, Oregon Health & Science University, Portland, OR, USA. cphillip3@hotmail.com.
authors.forename: Charles R
authors.initials: CR
authors.lastname: Phillips
authors.affiliation: CSEM Centre Suisse d'Electronique et de Microtechnique SA, Neuchâtel, Switzerland. josep.solaicaros@csem.ch.
authors.forename: Josep
authors.initials: J
authors.lastname: Solà
authors.affiliation: Systems and Computer Engineering, Carleton University, Ottawa, ON, Canada. adler@sce.carleton.ca.
authors.forename: Andy
authors.initials: A
authors.lastname: Adler
authors.affiliation: Department of Anaesthesiology, Center for Anaesthesiology and Intensive Care Medicine, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, D-20246, Hamburg, Germany. s.haas@uke.de.
authors.forename: Sebastian A
authors.initials: SA
authors.lastname: Haas
authors.affiliation: CSEM Centre Suisse d'Electronique et de Microtechnique SA, Neuchâtel, Switzerland. michael.rapin@csem.ch.
authors.forename: Michael
authors.initials: M
authors.lastname: Rapin
authors.affiliation: Swisstom AG, Landquart, Switzerland. shb@swisstom.com.
authors.forename: Stephan H
authors.initials: SH
authors.lastname: Böhm
authors.affiliation: Department of Anaesthesiology, Center for Anaesthesiology and Intensive Care Medicine, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, D-20246, Hamburg, Germany. dreuter@uke.de.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Reuter
mesh_terms: D055371:Acute Lung Injury / Q000150:complications*; D000818:Animals; D004195:Disease Models, Animal; D017097:Electric Impedance / Q000627:therapeutic use*; D015633:Extravascular Lung Water / Q000502:physiology; D019301:Oleic Acid / Q000009:adverse effects; D011654:Pulmonary Edema / Q000175:diagnosis*; D011897:Random Allocation; D012965:Sodium Chloride / Q000009:adverse effects; D013552:Swine; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D019301:Oleic Acid; D012965:Sodium Chloride