(W.B. Saunders, Philadelphia, PA)Evolution of Pulmonary Edema
Steps of alveolar edema. Initially (b) increased capillary pressure causes fluid transudation into the interstitial compartment. Tight junctions between alveolar epithelial cells prevent flooding of the alveolar space, and the fluid is drawn into the peribronchovascular adventitia for clearance by the lymphatics. A greater rise in intracapillary pressure can lead to "stress failure" of the alveolar capillary membrane, i.e. separation of the intercellular junctions between epithelial cells and endothelial cells. This does permit flooding of the alveolar space with fluid (c and d).
