Pulmonary Edema

Pulmonary Edema is accumulation of excess fluid in the interstitium or the alveolar airspaces of the lung parenchyma. The causes of Pulmonary Edema are mainly-

a. Cardiogenic- where backward venous congestion leads to accumulation of fluid in the interstitium and the alveoli. Examples- Left heart failure, Constrictive pericarditis etc.

b. Non cardiogenic- where primary injury to the alveolocapillary membrane leads to the edema. Examples- Pneumonia, any other toxin damaging the alveolocapillary membrane.

On microscopy, pink acellular fluid collection is seen in the interstitium initially and in long standing cases, in the alveoli. The lungs, on gross examination, are heavy and boggy in consistency.