title: Dynamic alveolar mechanics in four models of lung injury.
abstract: OBJECTIVE
  To determine whether pathological alterations in alveolar mechanics (i.e., the dynamic change in alveolar size and shape with ventilation) at a similar level of lung injury vary depending on the cause of injury.
  
  
  METHODS
  Prospective controlled animal study in a university laboratory.
  
  
  METHODS
  30 male Sprague-Dawley rats (300-550 g).
  
  
  METHODS
  Rats were separated into one of four lung injury models or control (n=6): (a) 2% Tween-20 (Tween, n=6), (b) oleic acid (OA, n=6), (c) ventilator-induced lung injury (VILI, PIP 40/ZEEP, n=6), (d) endotoxin (LPS, n=6). Alveolar mechanics were assessed at baseline and after injury (PaO2/FIO2 <300 mmHg) by in vivo microscopy.
  
  
  METHODS
  Alveolar instability (proportional change in alveolar size during ventilation) was used as a measurement of alveolar mechanics.
  
  
  RESULTS
  Alveoli were unstable in Tween, OA, and VILI as hypoxemia developed (baseline vs. injury: Tween, 7+/-2% vs. 67+/-5%; OA: 3+/-2% vs. 82+/-9%; VILI, 4+/-2% vs. 72+/-5%). Hypoxemia after LPS was not associated with significant alveolar instability (baseline vs. injury: LPS, 3+/-2 vs. 8+/-5%).
  
  
  CONCLUSIONS
  These data demonstrate that multiple pathological changes occur in dynamic alveolar mechanics. The nature of these changes depends upon the mechanism of lung injury.
authors.affiliation: Department of Surgery, Upstate Medical University, 750 E Adams Street, Syracuse, NY 13210, USA. DiRoccoJ@upstate.edu
authors.forename: Joseph D
authors.initials: JD
authors.lastname: DiRocco
authors.forename: Lucio A
authors.initials: LA
authors.lastname: Pavone
authors.forename: David E
authors.initials: DE
authors.lastname: Carney
authors.forename: Charles J
authors.initials: CJ
authors.lastname: Lutz
authors.forename: Louis A
authors.initials: LA
authors.lastname: Gatto
authors.forename: Steve K
authors.initials: SK
authors.lastname: Landas
authors.forename: Gary F
authors.initials: GF
authors.lastname: Nieman
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D006439:Hemodynamics; D000860:Hypoxia / Q000503:physiopathology; D008070:Lipopolysaccharides; D008297:Male; D019301:Oleic Acid; D011446:Prospective Studies; D011650:Pulmonary Alveoli / Q000503:physiopathology*; D011654:Pulmonary Edema / Q000473:pathology; D011659:Pulmonary Gas Exchange; D051381:Rats; D017207:Rats, Sprague-Dawley; D012121:Respiration, Artificial / Q000009:adverse effects; D012128:Respiratory Distress Syndrome / Q000209:etiology / Q000503:physiopathology*; D015656:Respiratory Mechanics
chemical_list: D008070:Lipopolysaccharides; D019301:Oleic Acid