In its harmless form, almost all of us have had edema at one time or another, for example, puffy eyelids in the morning after drinking too much alcohol, swollen feet in the summer, or even swelling after an insect bite. However, edema, also known as dropsy, can also be a symptom of a serious disease. What is edema and how is it treated? Find out here.
Edema: definition
Edema, often referred to as “dropsy,” is the retention of water from the vascular system in interstitial tissue, usually connective tissue. There is usually painless swelling in the affected area. Typical: If you press on the swelling with your finger, a dent remains that only gradually disappears. Edemas are not a disease in their own right, but symptoms of existing underlying diseases. They can occur sporadically, but also throughout the body and affect many other regions besides the skin, for example the lungs (pulmonary edema) or the brain (cerebral edema).
How does edema develop?
Normally, there is a balance between the transfer of fluid from the smallest blood vessels – the arterial capillaries – into the connective and supporting tissues and the outflow of tissue water into the venous capillaries and its drainage via the lymphatic vessels. In the case of edema, this fluid exchange between the capillaries and the tissue is disturbed, i.e. more water is transferred to the tissue than is removed. This is the case, for example, with all diseases that affect blood circulation, such as cardiac and renal insufficiency. In the former, the pumping capacity of the heart is impaired, so that the return flow to the heart is restricted and the water collects – in accordance with gravity – primarily in the area of both ankles and the backs of the feet. In kidney weakness, proteins are excreted in the urine that would otherwise attract and thus retain the water in the blood. Other common causes of edema are cirrhosis of the liver (leading to edema in the abdomen = ascites), allergies, and medications such as calcium channel blockers used for heart disease. Some congenital diseases are also associated with edema.
Common forms of edema
Common forms and types of edema include:
- Leg edema
- Pulmonary edema
- Brain edema
- Angioedema
A special form is lymphedema, in which the lymph nodes are not functional or have been destroyed or removed due to disease (for example, cancer). As a result, tissue fluid and degradation products can no longer be sufficiently removed. Swelling of the tissue occurs, which can affect only individual limbs, but also the entire body. The tissue appears bloated and doughy, and the swellings are – in contrast to “normal” edema – difficult to compress.
Leg edema: water in the legs
Leg edema, which is an accumulation of water in the legs, is caused, for example, by weak veins whose venous valves no longer function well enough. The used blood, which should actually be transported to the heart, pools in the legs. As a result, high pressure builds up in the vessels, too much fluid is pressed out of the blood into the surrounding tissue; the leg swells. Other causes include heart and kidney weakness.
Pulmonary edema – water in the lungs
The transfer of fluid from the capillary vessels to the lungs most often occurs due to chronic weakness of the left ventricle – the blood is not sufficiently pumped on into the large circulation and backs up into the pulmonary circulation. Other causes of pulmonary edema include kidney weakness, lung disease and altitude sickness.
Cerebral edema: life-threatening water retention.
Life-threatening increased fluid retention or redistribution in brain tissue results from various external and internal disorders, for example:
- Tumors
- Inflammations
- Poisonings
- Vascular damage
- Brain diseases
- Injuries
- Operations or
- Altitude sickness
Because the bony skull has no way to expand, cerebral edema can compress important brain areas and supplying vessels, leading to decreased blood flow and tissue death.
Angioedema: edema in different parts of the body
Formerly called Quincke’s edema, this accumulation of water in subcutaneous tissues presents as transient, often massive swellings, especially on the face (lips and eyelids), and less commonly on the tongue, genitals, and other organs. They usually do not itch, but they can be painful, depending on the severity of the swelling. If the larynx is affected, there is even a risk of suffocation. Normally, angioedema resolves within one to three days. It occurs either in the context of an allergic reaction (mediated by the messenger substance histamine) or – much more rarely – as a result of the insufficient function of a certain molecule (C1 inhibitor), which slows down the immune system in uncontrolled reactions. This form is usually congenital (hereditary angioedema).
Therapy of “dropsy”
Because edema is an expression of an underlying disease, its treatment is the first priority. Often, the extent of edema (or its decrease) is a good indicator of whether therapy for heart or kidney failure, for example, is effective. Depending on the location and severity of the edema, intensive medical treatment may be necessary – for example, in the case of cerebral edema and pulmonary edema. The swelling in lymphedema is treated with special compression stockings or gloves and sleeves that exert pressure on the limbs; the affected limbs are elevated. Special massages (lymphatic drainage) and physiotherapy provide additional relief.
