Abstract

BACKGROUND
Experimentally, maintaining high pressure or high volume ventilation in animal models produces an acute lung injury, however, there was little information on remodeling. We investigated the collagen synthesis in a rat model of ventilator-induced lung injury.
METHODS
Rats were ventilated with room air at 85 breaths/minute for 2 hours either tidal volume 7 ml/kg or 20 ml/kg (V(T)7 or V(T)20, respectively). After 2 hours of ventilation, rats were placed in the chamber for 24 hours. Lung collagen was evaluated by immunohistochemistry (n=5) and collagen was quantitated by collagen assay (n=5). Static compliance (Csta) of the whole lung as obtained from the pressure volume curves.
RESULTS
Type I collagen was an increase in expression in the interstitium with large V(T) (20 ml/ kg) ventilation after 2 hours of mechanical ventilation (MV), and further increased expression after 24 hours of recovery period. Static lung compliance was significantly (p<0.05) decreased in the V(T)20 compared with V(T)7 (0.221+/-0.05 vs 0.305+/-0.06 ml/cm H2O) after 2 hours of MV. There was a further decrease in lung compliance after 24 hours of recovery period (0.144+/-0.07 vs 0.221+/-0.05, p<0.05) in the V(T)20.
CONCLUSIONS
Large tidal volume ventilation causes an increase in type 1 collagen expression with reduction of lung compliance.

• Keywords: Collagen;Lung compliance;Ventilator-induced lung injury;