ABSTRACT
Chronic lung diseases (CLD) of infants are diseases of the airways and parenchyma that progress from a phase of tissue injury and inflammation to scarring and distortion of the lung architecture. The most important disease in infants resulting in lung fibrosis is bronchopulmonary dysplasia (BPD). There is considerable circumstantial evidence that immaturity, barotrauma from mechanical ventilation, and exposure to high levels of O2 contribute to lung fibrosis. The processes that lead to fibrous tissue formation in BPD are analogous to wound healing, and involve formation of a provisional matrix at the site of injury, followed by reconstitution of normal tissue or scar formation if the injury is severe or smoldering. If severe, scar formation leads to distortion of lung parenchyma, impaired lung function, and clinical disease.
