Cardiogenic pulmonary edema occurs when the pressure inside the capillaries exceeds the vessel threshold. The fluid extravasates out of the vessels into the interstitial space and then into the alveoli. The fluid makes the interlobular septa swell and become irregular.

In the modern era, clinicians should inspect the internal organs just as they inspect the external organs. If a patient's leg is swollen, you should inspect the joints and skin. You should also inspect the leg veins with #pocus.