title: PEEP decreases atelectasis and extravascular lung water but not lung tissue volume in surfactant-washout lung injury.
abstract: OBJECTIVE
  To examine the effects of positive end-expiratory pressure (PEEP) on extravascular lung water (EVLW), lung tissue, and lung volume.
  
  
  METHODS
  Experimental animal study at a university research facility.
  
  
  METHODS
  Fifteen adult sheep.
  
  
  METHODS
  All animals were studied before and after saline washout-induced lung injury while ventilated with sequentially increasing PEEP (0, 7, 14, or 21 cmH(2)O).
  
  
  RESULTS
  Lung volume was determined by computed tomography and EVLW by the thermal dye dilution technique. Saline washout significantly increased lung tissue volume (21+/-3 to 37+/-5 ml/kg) and EVLW (9+/-2 to 36+/-9 ml/kg). While increasing levels of PEEP reduced EVLW (30+/-7, 24+/-8, and 18+/-4 ml/kg), lung tissue volume remained constant. Total lung volume significantly increased (50+/-8 ml/kg at PEEP 0 to 77+/-12 ml/kg at PEEP 21). Nonaerated lung volume significantly decreased and was closely correlated with the changes in EVLW ( r=0.67). In addition, a highly significant correlation was found between PEEP-induced decrease in nonaerated lung volume and decrease in transpulmonary shunt ( r=0.83).
  
  
  CONCLUSIONS
  The main findings are as follows: (a) PEEP effectively decreases EVLW. (b) The decrease in EVLW is closely correlated with the PEEP-induced decrease in nonaerated lung volume, making EVLW a valuable bedside parameter indicating alveolar recruitment, similar to measurements of transpulmonary shunt. (c) As excess tissue volume remained constant, however, EVLW may not be suitable to reflect overall severity of lung disease
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Faculty of Clinical Medicine, University Hospital, Theodor-Kutzer-Ufer, 68167, Mannheim, Germany. thomas.Luecke@anaes.ma.uni-heidelberg.de
authors.forename: Thomas
authors.initials: T
authors.lastname: Luecke
authors.forename: Harry
authors.initials: H
authors.lastname: Roth
authors.forename: Peter
authors.initials: P
authors.lastname: Herrmann
authors.forename: Alf
authors.initials: A
authors.lastname: Joachim
authors.forename: Gerald
authors.initials: G
authors.lastname: Weisser
authors.forename: Paolo
authors.initials: P
authors.lastname: Pelosi
authors.forename: Michael
authors.initials: M
authors.lastname: Quintel
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis; D004195:Disease Models, Animal; D004395:Dye Dilution Technique; D015633:Extravascular Lung Water; D006439:Hemodynamics; D008170:Lung Compliance; D008176:Lung Volume Measurements; D011175:Positive-Pressure Respiration / Q000379:methods*; D001261:Pulmonary Atelectasis / Q000209:etiology* / Q000517:prevention & control; D011652:Pulmonary Circulation; D011659:Pulmonary Gas Exchange; D012128:Respiratory Distress Syndrome / Q000139:chemically induced / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D015656:Respiratory Mechanics; D012720:Severity of Illness Index; D012756:Sheep; D012965:Sodium Chloride; D007507:Therapeutic Irrigation; D013815:Thermodilution; D014057:Tomography, X-Ray Computed
chemical_list: D015415:Biomarkers; D012965:Sodium Chloride