LE BASI MORFOGENETICHE ULTRASTRUTTURALI DELLA 'ADULT RESPIRATORY DISTRESS SYNDROME' (ARDS)

Sequential study of the submicroscipic pathological events characterising the natural history of adult respiratory distress syndrome has pinpointed three different development stages related to clinical course and prognosis. In the first stage, the decisive biological element is represented by the increase in capillary permeability, whose morphological substrate consists of the distension of intercell junctions. The result is the formation of interstitial oedema with the characteristics of the exudate. In the second stage, when reversibility is still possible, fluid and proteins pass into the alveolus. Finally, in the third stage, the persisting stimulus of pulmonary capillaries leads to the formation of hyaline membranes and to a reactive lung response in the form of interstitial fibrinogenesis and hyperplasia of granular pneumocytes.