[Lung histology in experimental drowning].

Experiments were carried out on anesthetized rats which had to aspirate actively watery fluids of different osmolarities (range: freshwater--2.9% NaCl solution) by a tracheotomy tube. The cytologic and histological alterations which are to be found are mainly of osmotic origin. In aspiration of hypotonic solutions macroscopy shows the well-known emphysema aquosum. Corresponding to the structure of the respiratory system, the histological alterations show areolar limitations. The influx of fluids causes a wide range of reactions from the development of an alveolar-interstitial edema in combination with intracellular and intercellular vesiculation, karyolysis with swollen homogenized nuclei of the subendothelial, septal, and epithelial cells to a necrosis of all the cellular elements. A pronounced microangiopathy with edema of the vascular walls, a hydrops of the myocytes containing large vacuoles and perivascular edema with dilated lymphatic channels are likewise to be found. The alveolar macrophages are considerably increased. Sporadic ruptures of the alveolar walls and microhemorrhages occur. In salt water drowning alterations of the shape of both the erythrocytes (thorn-apple form) and the alveolar epithelium in combination with a striking of the pneumocytes and villous transformation prevail. Besides, these are capillary hyperemia and sludge. In a careful specimen analysis a differentiation of the findings between vital reactions and postmortem fluid impact is possible.