Est,L was reduced in both HYPO and HYPER groups when lungs were recruited. However, Est,L did not example change in NORMO group after RMs.Table 3Arterial blood gases and static lung elastanceThe fraction of alveolar collapse was higher in HYPER (42%) compared with HYPO (27%) and NORMO (28%) groups. RMs decreased alveolar collapse independently of volemic status; nevertheless, alveolar collapse was more frequent in HYPER (26%) than NORMO (17%) and HYPO (12%) groups. Hyperinflated areas were not detected in any group (Figure (Figure22).Figure 2Volume fraction of the lung occupied by collapsed alveoli (gray) or normal pulmonary areas (white). Animals were randomly assigned to hypovolemia (HYPO), normovolemia (NORMO) or hypervolemia (HYPER) with recruitment maneuver (RM-CPAP) or not (NR). All …

Lung W/D ratio was higher in HYPER than in HYPO and NORMO groups. Furthermore, lung W/D ratio was increased in NORMO and HYPER groups after RMs (Figure (Figure33).Figure 3Wet-to-dry ratio measured after one hour of mechanical ventilation. Animals were randomly assigned to hypovolemia (HYPO), normovolemia (NORMO) or hypervolemia (HYPER) with recruitment maneuver (RM-CPAP) or not (NR). Values are mean �� standard …In the NR groups, lung W/D ratio was positively correlated with the fraction area of alveolar collapse (r = 0.906, P < 0.001) and Est,L (r = 0.695, P < 0.001), and negatively correlated with PaO2 (r = -0.752, P < 0.001). Furthermore, the fraction area of alveolar collapse was positively correlated with Est,L (r = 0.681, P < 0.001) and negatively correlated with PaO2 (r = -0.

798, P < 0.001). In the RM-CPAP groups, lung W/D ratio was positively correlated with the fraction area of alveolar collapse (r = 0.862, P < 0.001) and Est,L (r = 0.704, P < 0.001), while there was no correlation with PaO2. In addition, the fraction area of alveolar collapse was positively correlated with Est,L (r = 0.803, P < 0.001), but not with PaO2.Figure Figure44 depicts typical electron microscopy findings in each group. ALI animals showed injury of cytoplasmic organelles in type II pneumocytes (PII) and aberrant lamellar bodies, as well as endothelial cell and neutrophil apoptosis. Detachment of the alveolar-capillary membrane and endothelial cell injury were more pronounced in HYPER compared with HYPO and NORMO groups (Table (Table4).4).

When RMs were applied, hypervolemia resulted in increased detachment of the alveolar capillary membrane, as well as injury of PII and endothelium, compared with normovolemia.Table 4Semiquantitative analysis of electron microscopyFigure 4Electron microscopy of lung parenchyma. Animals were randomly assigned to hypovolemia (HYPO), normovolemia (NORMO) or hypervolemia Batimastat (HYPER) with recruitment maneuver (RM-CPAP) or not (NR). Type II pneumocyte (PII) as well as alveolar capillary membrane …