Oleic acid vs saline solution lung lavage-induced acute lung injury: effects on lung morphology, pressure-volume relationships, and response to positive end-expiratory pressure.
OBJECTIVE
To compare two lung injury models (oleic acid [OA] and saline solution washout [SW]) regarding lung morphology, regional inflation, and recruitment during static pressure-volume (PV) curves, and the effects of positive end-expiratory pressure (PEEP) below and above the lower inflection point (Pflex).


METHODS
Fourteen adult pigs underwent OA or SW lung injury. Lung volumes were measured using CT. PV curves were obtained with simultaneous CT scanning at lung apex and base. Fractional inflation and recruitment were compared to data on PEEP above and below Pflex.


RESULTS
Severity of lung injury was comparable. At zero PEEP, SW showed an increased amount of edema and poorly aerated lung volume, recruitment during inspiration, and a better oxygenation response with PEEP. Whole-lung PV curves were similar in both models, reflecting changes in alveolar inflation or deflation. On the inspiratory PV limb, recruitment and inflation were on the same line, while there was a substantial difference between deflation and derecruitment on the expiratory limb. PEEP-induced recruitment at lung apex and base was at or above the derecruitment line on the expiratory limb and showed no relationship to the whole-lung expiratory PV curve.


CONCLUSIONS
The following conclusions were made: (1) OA and SW models are comparable in mechanics but not in lung injury characteristics; (2) neither inspiratory nor expiratory whole-lung PV curves are useful to select PEEP in order to optimize recruitment; and (3) after recruitment, there is no difference in derecruitment between the models at high PEEP, while more collapse occurs at lower PEEP in the basal sections of SW lungs.
Luecke
Thomas
T
Department of Anesthesiology and Critical Care Medicine, University Hospital of Mannheim, Faculty of Clinical Medicine Mannheim, University of Heidelberg, Theodor-Kutzer Ufer, Germany. thomas.luecke@anaes.ma.uni-heidelberg.de
Meinhardt
Juergen P
JP
Herrmann
Peter
P
Weiss
Andreas
A
Quintel
Michael
M
Pelosi
Paolo
P
D000818:Animals; D004195:Disease Models, Animal; D008168:Lung / Q000473:pathology* / Q000503:physiopathology; D008176:Lung Volume Measurements; D019301:Oleic Acid / Q000633:toxicity; D011175:Positive-Pressure Respiration / Q000379:methods*; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012128:Respiratory Distress Syndrome / Q000139:chemically induced / Q000473:pathology / Q000628:therapy; D012720:Severity of Illness Index; D012965:Sodium Chloride / Q000633:toxicity; D013552:Swine; D007507:Therapeutic Irrigation / Q000009:adverse effects
D019301:Oleic Acid; D012965:Sodium Chloride