[Pulmonary edemas. Anatomic study].

Whatever the etiology of pulmonary edema, i.e. increase in intrapulmonary water, edema passes through three, moreover intricate phases: 1- intracellular edema clearly visible in the type 1 pneumocyte. This intracellular edema appears at the same time as: 2- interstitial edema; that which appears when: 3- numerous vesicules of pinocytosis and separation of the capillary endothelial cells account for it; 4- intra-alveolar edema itself appears later and corresponds to the major clinical phase of pulmonary edema. There is nothing surprising about this as the cellular functions of pneumocytes are impervious as can be shown for example by studies carried out with tracers. This intracellular alveolar edema seems to have two different aspects depending on whether the experimental conditions create an acute or sub-acute pathology. In the acute form, the edema is poor in lipids and in proteins. In the sub-acute of chronic forms, it is on the contrary very rich in them. 5-In the last phase, a veritable desquamation of the pneumocytes then of the endothelial cells is produced which is very frequently lethal. If survival occurs, two sorts of lesions are found: -colonisation of the alveolar surface with type II pneumocytes; - occurrence of possible intersitial fibrosis. The remarkable fact is that such lesions are visible in a more or less identical manner in all cases of pulmonary edema, whether they be hemodynamic or lesional. The morphology does not confirm this physiopathological distinction which is moreover questionable as all pulmonary edema become lesional sooner or later.