Beyond the Basics: Pulmonary Edema
There are several causes that lead to pulmonary edema, some permanent and some temporary. Pulmonary edema is due either to failure of the heart as a forward pump or maldistribution of fluid within the pulmonary circuit. The movement of excess fluid into the alveoli as a result of an alteration in one or more of Starling's forces (forces that cause interchange of fluids between the intravascular and interstitial spaces) is a key consideration in pulmonary edema. In cardiogenic pulmonary edema, high pulmonary capillary pressure (created by high pressure inside the left atrium) is responsible for the abnormal fluid movement. In contrast, noncardiogenic pulmonary edema occurs when factors other than elevated capillary pressure are responsible for changes in the internal environment of the alveoli.