Oedema

Oedema is the abnormal accumulation of fluid in body tissues, causing swelling. It occurs when fluid leaks from blood vessels into surrounding tissues at a greater rate than the lymphatic system can drain it away. Oedema can be localised (affecting one area) or generalised (affecting the whole body).

In cardiac conditions, oedema is most commonly a sign of heart failure. When the heart pumps ineffectively, fluid backs up in the venous system. In left heart failure, fluid accumulates in the lungs (pulmonary oedema), causing breathlessness. In right heart failure (or combined heart failure), fluid backs up into the systemic venous circulation, causing dependent oedema: swelling that accumulates in the lower legs, ankles, and feet in people who are upright, or in the sacral area in those who are bedbound. Facial and abdominal oedema (ascites) can also occur in severe cases.

Oedema is assessed clinically by examining for pitting, in which pressing a finger into the swollen area leaves a temporary indentation as the displaced fluid moves. The degree of pitting is graded and provides an indication of severity. It is monitored by daily weight measurement: a rapid weight gain of 1 to 2 kg over a few days often indicates fluid retention before visible swelling appears.

Treatment of cardiac oedema typically involves diuretic medication (such as furosemide) to increase fluid excretion through the kidneys, alongside treatment of the underlying heart condition. Fluid and salt restriction may also be advised. Monitoring electrolytes (particularly potassium) is important when diuretics are used, as imbalances can trigger cardiac arrhythmias.