Edema


Edema, also spelled oedema, and also known as fluid retention, swelling, dropsy and hydropsy, is the build-up of fluid in the body's tissue. Most commonly, the legs or arms are affected. Symptoms may include skin that feels tight, the area feeling heavy, and joint stiffness. Other symptoms depend on the underlying cause.
Causes may include venous insufficiency, heart failure, kidney problems, low protein levels, liver problems, deep vein thrombosis, infections, kwashiorkor, angioedema, certain medications, and lymphedema. It may also occur in immobile patients, or with temporary immobility such as prolonged sitting or standing, and during menstruation or pregnancy. The condition is more concerning if it starts suddenly, or pain or shortness of breath is present.
Treatment depends on the underlying cause. If the underlying mechanism involves sodium retention, decreased salt intake and a diuretic may be used. Elevating the legs and support stockings may be useful for edema of the legs. Older people are more commonly affected. The word is from the Ancient Greek οἴδημα oídēma meaning 'swelling'.

Signs and symptoms

Specific area

An edema will occur in specific organs as part of inflammation, tendinitis or pancreatitis. Certain organs develop edema through tissue specific mechanisms. Examples of edema in specific organs:
  • Peripheral edema is extracellular fluid accumulation in the lower extremities caused by the effects of gravity, and occurs when fluid pools in the lower parts of the body, including the feet, legs, or hands. This often occurs in immobile people, such as paraplegics or quadriplegics, pregnant women, or in otherwise healthy people due to hypervolemia or maintaining a standing or seated posture for an extended time. It can occur due to diminished venous return of blood to the heart due to congestive heart failure or pulmonary hypertension. It can also occur in people with increased hydrostatic venous pressure or decreased oncotic venous pressure, due to obstruction of lymphatic or venous vessels draining the lower extremity. Certain drugs can cause edema of the feet.
  • Cerebral edema is extracellular fluid accumulation in the brain. It can occur in toxic or abnormal metabolic states and conditions such as systemic lupus or reduced oxygen at high altitudes. It causes drowsiness or loss of consciousness, leading to brain herniation and death.
  • Pulmonary edema occurs when the pressure in blood vessels in the lung is raised because of obstruction to the removal of blood via the pulmonary veins. This is usually due to failure of the left ventricle of the heart. It can also occur in altitude sickness or on inhalation of toxic chemicals. Pulmonary edema produces shortness of breath. Pleural effusions may occur when fluid also accumulates in the pleural cavity.
  • Edema may also be found in the cornea of the eye with glaucoma, severe conjunctivitis, keratitis, or after surgery. Affected people may perceive coloured haloes around bright lights.
  • Edema surrounding the eyes is called periorbital edema . The periorbital tissues are most noticeably swollen immediately after waking, perhaps as a result of the gravitational redistribution of fluid in the horizontal position.
  • Common appearances of cutaneous edema are observed with mosquito bites, spider bites, bee stings, and skin contact with certain plants such as poison ivy or western poison oak, the latter of which are termed contact dermatitis.
  • Another cutaneous form of edema is myxedema, which is caused by increased deposition of connective tissue. In myxedema edema is caused by an increased tendency of the tissue to hold water within its extracellular space. In myxedema, this is due to an increase in hydrophilic carbohydrate-rich molecules deposited in the tissue matrix. Edema forms more easily in dependent areas in the elderly and this is not well understood. Estrogens alter body weight in part through changes in tissue water content. There may be a variety of poorly understood situations in which transfer of water from tissue matrix to lymphatics is impaired because of changes in the hydrophilicity of the tissue or failure of the 'wicking' function of terminal lymphatic capillaries.
  • Myoedema is localized mounding of muscle tissue due to percussive pressure, such as flicking the relaxed muscle with the forefinger and thumb. It produces a mound, visible, firm and non-tender at the point of tactile stimulus approximately 1–2 seconds after stimulus, subsiding back to normal after 5–10 seconds. It is a sign in hypothyroid myopathy, such as Hoffmann syndrome.
  • In lymphedema, abnormal removal of interstitial fluid is caused by failure of the lymphatic system. This is most commonly due to a failure of normal pumping action of muscles due to immobility—most strikingly in conditions such as multiple sclerosis or paraplegia. Or it may be due to obstruction by a cancer or by enlarged lymph nodes; or to destruction of lymph vessels or nodes by radiotherapy; or from infiltration of the lymphatic system by infection. It has been suggested that the edema that occurs following use of aspirin-like cyclo-oxygenase inhibitors, such as ibuprofen or indomethacin, may be due to inhibition of lymph heart action.

    Generalized

A rise in hydrostatic pressure occurs in cardiac failure. A fall in osmotic pressure occurs in nephrotic syndrome and liver failure.
Causes of edema that are generalized to the whole body can cause edema in multiple organs and peripherally. For example, severe heart failure can cause pulmonary edema, pleural effusions, ascites and peripheral edema. Such severe systemic edema is called anasarca. In rare cases, a parvovirus B19 infection may cause generalized edemas.
Although a low plasma oncotic pressure is widely cited for the edema of nephrotic syndrome, most physicians note that the edema may occur before there is any significant protein in the urine or fall in plasma protein level. Most forms of nephrotic syndrome are due to biochemical and structural changes in the basement membrane of capillaries in the kidney glomeruli, and these changes occur, if to a lesser degree, in the vessels of most other tissues of the body. Thus the resulting increase in permeability that leads to protein in the urine can explain the edema if all other vessels are more permeable as well.
As well as the previously mentioned conditions, edemas often occur during the late stages of pregnancy in some women. This is more common with those of a history of pulmonary problems or poor circulation also being intensified if arthritis is already present in that particular woman. Women who already have arthritic problems most often have to seek medical help for pain caused from over-reactive swelling. Edemas that occur during pregnancy are usually found in the lower part of the leg, usually from the calf down.
Hydrops fetalis is a condition in a baby characterized by an accumulation of fluid in at least two body compartments.

Cause

Heart

The pumping force of the heart should help to keep a normal pressure within the blood vessels. But if the heart begins to fail the pressure changes can cause very severe water retention. In this condition water retention is mostly visible in the legs, feet and ankles, but water also collects in the lungs, where it causes a chronic cough. This condition is usually treated with diuretics; otherwise, the water retention may cause breathing problems and additional stress on the heart.

Kidneys

Another cause of severe water retention is kidney failure, where the kidneys are no longer able to filter fluid out of the blood and turn it into urine. Kidney disease often starts with inflammation, for instance in the case of diseases such as nephrotic syndrome or lupus. This type of water retention is usually visible in the form of swollen legs and ankles.

Liver

of the liver is a common cause of edema in the legs and abdominal cavity.

Veins

Phlebetic lymphedema is seen in untreated chronic venous insufficiency and is the most common type of edema. It is a combination venous/lymphatic disorder that originates in defective "leaky" veins that allows the blood to back flow, slowing the return of the blood to the heart. The venous pressure in the legs changes dramatically while standing compared to lying down. How much pressure there is depends on the person's height, in the average adult person, it is 8 mm Hg while lying down and 100 mm Hg while standing.
In venous insufficiency, venous stasis results in abnormally high venous pressure and greater permeability of blood capillaries, to drain the blood through the lymphatic system. The lymphatic system slowly removes excess fluid and proteins from the veins in the lower legs towards the upper body; however, as it is not as efficient as an unimpaired circulatory system, swelling is visible, particularly in the ankles and lower leg. The chronic increased fluid in the lymphatic system and capillary hyperpermeability causes an inflammatory response which leads to tissue fibrosis of both veins and lymphatic system, opening of arteriovenous shunts, all of which then worsens the condition in a vicious cycle.

Others

Swollen legs, feet and ankles are common in late pregnancy. The problem is partly caused by the weight of the uterus on the major veins of the pelvis. It usually clears up after delivery of the baby, and is mostly not a cause for concern, though it should always be reported to a doctor.
Lack of exercise is another common cause of water retention in the legs. Exercise helps the leg veins work against gravity to return blood to the heart. If blood travels too slowly and starts to pool in the leg veins, the pressure can force too much fluid out of the leg capillaries into the tissue spaces. The capillaries may break, leaving small blood marks under the skin. The veins themselves can become swollen, painful and distorted – a condition known as varicose veins.
Causes of bilateral pedal edema:.
  • Drugs like CCBs, gabapentin, pregabalin, NSAIDs, steroids, IL-6 inhibitors.
  • Chronic leg vein insufficiency.
  • Reduced mobility > reduced calf muscle activity>dependent edema/ gravitational edema
  • IVC obstruction/ other causes of venous stasis
  • Capillary leakage: acute endothelial dysfunction, sepsis, dengue, systemic capillary leakage syndrome .
  • Inflammatory edema: vasculitis/ arthritis / dermatomyositis/panniculitis
  • Vasomotor dysregulation like sympathetic denervation in diabetes, spinal cord injury, double hemiplegia, paraplegia, chronic stress related.
  • Heat edema- in patients returning from cold climate
  • Early lymphatic dysfunction including obesity
  • Other endocrine- Cushing/Conn/PMS
  • Idiopathic cyclical edema
Muscle action is needed not only to keep blood flowing through the veins but also to stimulate the lymphatic system to fulfil its "overflow" function. Long-haul flights, lengthy bed-rest, immobility caused by disability and so on, are all potential causes of water retention. Even very small exercises such as rotating ankles and wiggling toes can help to reduce it.
Certain medications are prone to causing water retention. These include estrogens, thereby including drugs for hormone replacement therapy or the combined oral contraceptive pill, as well as non-steroidal anti-inflammatory drugs and beta-blockers.
Premenstrual water retention, causing bloating and breast tenderness, is common.