Edema << ih DEE muh >> is the swelling of body tissues caused by fluid build-up between cells. Cells are bathed and nourished by fluid that continually seeps from the capillaries, the tiniest blood vessels. Normally, the seepage is balanced by reabsorption of fluid into the capillaries and by drainage into the lymphatic system (see Lymphatic system). When this balance is upset, edema results.
Edema may be local–that is, limited to one part of the body–or it may be general, affecting tissues throughout the body. Local edema commonly results when injured capillaries leak their contents into nearby tissue spaces. Such local edema is corrected by treating the injury and by elevating the affected body part.
The most common cause of general edema is heart failure. When a weak heart does not circulate the blood effectively, the kidneys cannot remove enough water and salt from the bloodstream. As a result, the blood volume increases, and excess liquid seeps into the body tissues, particularly the legs and lungs. The condition is called pulmonary edema when excess fluid accumulates in the lungs, causing shortness of breath. Physicians treat edema due to heart failure with drugs or surgery to improve heart function. Patients also receive diuretics, medicines that increase the amount of water and salt eliminated by the kidneys.
General edema also often results if poor diet, liver disease, or kidney disease causes a drop in the blood plasma’s protein content. Proteins in blood plasma play a major role in the blood’s ability to retain fluid. High-protein diets help correct this type of edema.
Problems with lymphatic drainage cause lymphedema. This condition often requires long periods of bed rest, with the affected body parts elevated and tightly wrapped to reduce swelling. The most dramatic form of lymphedema is elephantiasis, a disease in which parts of the body swell and the skin becomes rough and thickened like that of an elephant.
See also Congestive heart failure; Diuretic; Elephantiasis.
