Dynamic alveolar mechanics in four models of lung injury.
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.
DiRocco
Joseph D
JD
Department of Surgery, Upstate Medical University, 750 E Adams Street, Syracuse, NY 13210, USA. DiRoccoJ@upstate.edu
Pavone
Lucio A
LA
Carney
David E
DE
Lutz
Charles J
CJ
Gatto
Louis A
LA
Landas
Steve K
SK
Nieman
Gary F
GF
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
D008070:Lipopolysaccharides; D019301:Oleic Acid