Pulmonary Edema- CXR

"Early signs of pulmonary edema (intersticial edema) are the Kerley B lines, horizontal lines seen laterally in the lower zones, 2 cm long at last reach the lung edge. As the edema progress alveolar edema is observed with its "butterfly-batwing" pattern, characterized by the central predominance of shadows with a clear zone at periphery lobes. Other feature that may be seen is cardiac enlargement, in case of cardiac failure previously present. A helpful feature in distinguishing cardiac pulmonary edema from non cardiac pulmonary edema and from pneumonia, is the speed with which the edema appears and disappears. Substantial improvement in a 24 hour period is virtually diagnosis of cardiac pulmonary edema. These are two CXR done before and after decongestant therapy. "