The most common causes of pulmonary edema are cardiac failure, renal failure and injury edema (diffuse alveolar damage). The injury edema typically shows airspace consolidation due to exsudation of fluid in the periphery of the lung with air bronchograms, no interstitial fluid accumulation can be found and only rarely pleural effusions are present. Cardiac and renal edemas often show a mixed interstitial and alveolar transudation without air bronchograms. Pleural effusions are often present. Both usually have an increased heart-size and an increased vascular pedicle width. To distinguish them better one has to look at the distribution of the pulmonary edema: The cardiac edema typically shows a gravitational and the renal edema a central distribution.