The term oedema(swelling)refers to accumulation of fluid in tissue spaces. Oedema can occur nearly anywhere in the body. The location of the edema will depend, in part, on the underlying cause.
What causes oedema?
In most cases, the process of oedema formation begins when fluid leaks from the body’s smallest blood vessels, called capillaries, into the surrounding tissues. The leakage can occur because of changes in pressure in the capillaries, weakening of the capillary wall from disease, or other factors. This leakage of fluid from the blood compartment will result in a reduction of the effective blood volume. Kidney senses it and reduces the excretion of salt and water. This salt and water retention by the kidney ultimately maintains the volume of fluid circulating in the blood vessels. This will lead to further leakage of fluid from the capillaries. This causes accumulation of fluid in the body tissues (oedema develops).
What are the conditions, which cause oedema?
A number of conditions can result in oedema. For example, damage to the veins in the legs (venous insufficiency or varicose veins) can cause abnormal pooling or clotting of blood in these vessels, leading to edema. Pregnancy, drug (mostly blood pressure medications and pain killers medicines) and obstruction to lymphatic drainage can also cause peripheral edema. Diseases commonly associated with edema are kidney disease, heart failure, cirrhosis of the liver and low albumin level in the blood and reduced function of the thyroid gland.
a. Kidney disease
The oedema due to kidney disease is caused by an increase in pressure in the blood vessels that occurs when the kidneys fail to excrete the normal amount of sodium (salt) and water. The extra fluid (water) exerts pressure on the blood vessel walls, setting up the conditions for edema. Albumin in the blood is responsible for holding fluid in the vascular space (inside blood vessels) by preventing leakage of fluid through capillaries. Low levels of the albumin in the blood (as a result of leakage of albumin in the urine) in some people with kidney disease may contribute to the leakage of fluid from the capillaries. Oedema in acute nephritis and nephrotic syndrome characteristically makes the first appearance around the eyes and is followed by swelling of legs.
b. Heart failure
In heart failure, also called congestive heart failure, the heart is weakened and its pumping action is reduced. It can affect the right heart chambers, which receive blood from the body and pump it to the lungs to be filled with oxygen; or it can affect the left heart chambers, which pump oxygenated blood to the rest of the body.Heart failure develops as a result of other conditions that damage the heart. These include heart attacks due to coronary heart disease, diseases of the heart valves, and hypertension (high blood pressure).In right heart failure, pressure builds in the right chambers because they fail to pump blood efficiently. The pressure is reflected back to the blood vessels in the body that lead to the right chambers, frequently causing peripheral edema and, sometimes, ascites (accumulation of fluid in the abdomen). The patient therefore notices swelling in the legs and abdomen, as well as other symptoms.
In left heart failure, pressure builds in the left chambers because they are failing to pump blood efficiently. This time, the increased pressure is reflected in the large blood vessels that connect the left side of the heart with the lungs. This causes oedema in the lungs, or pulmonary oedema, and the patient feels shortness of breath.Some patients have heart failure in both the left and right chambers; others have primarily one or the other.
c. Cirrhosis (Chronic disease of the liver)
With cirrhosis, congestion in the liver leads to an increase in pressure within the blood vessels in the liver and, subsequently, in the blood vessels leading into the liver, causing ascites. The patient may have pronounced swelling in the abdomen, as well as oedema in the feet or, if the patient is lying down most of the day, swelling in the lower back (also called sacral oedema).
d. Venous insufficiency (Varicose veins)
A common cause of peripheral oedema in clinical practice is venous insufficiency, one cause of which is a syndrome that may occur after an episode of venous blood clots (called deep vein thrombosis). The oedema is usually limited to the lower extremities and may be unilateral, a finding that is not seen in those with other conditions.
Oedema can be a side effect of a wide variety of medications. Typical examples include blood pressure medications such as amlodipine and nifedipine. Nonsteroidal anti-inflammatory drugs (pain killer medications such as Ibuprofen, Voveran) can also result in the development of oedema.
Decreased function of the thyroid gland can cause salt and water accumulation in the body resulting in oedema.
Pregnant women retain a significant amount of sodium and water. Some of this excess fluid is required by the fetus and placenta, but mild edema is also commonly seen.
h. Ideopathic oedema
Ideopathic oedema is a condition, which usually affects women. Cause this clinical entity has not been clearly identified although several theories have been postulated. Diagnosis of idiopathic oedema can be made only after excluding other conditions.
How is edema treated?
Treatment is directed at the underlying disease. If possible, removing the excess fluid with diuretics, and minimizing further fluid accumulation by restricting sodium intake and other measures.
Diuretics (Lasix, Aldactone and Dytide) are medicines that stimulate the kidneys to remove fluid. Diuretics must be used carefully fluid removal decreases the circulating blood volume. In some patients, this can result in a decrease in blood pressure and other problems. Diuretics should be used in small doses initially and dose may be increased if required. It is better to use diuretics twice a day than once a day as it is more effective.
Although diuretics are beneficial in many types of edema, they are not appropriate in every case. In particular, diuretics are generally not recommended for edema caused by pregnancy, where fluid retention is generally normal, or venous insufficiency.
Restriction of sodium (Salt) and water in the diet
In most cases, the patient is advised to restrict dietary salt and foods containing sodium. Sodium can cause the kidneys to retain more fluid, worsening the edema. Water (fluid) intake should also be reduced.
Leg edema can be improved by elevating the legs and the use of elastic stockings, which can help drain excess fluid.
Treatment of the primary disease
Treatment of the primary disease, which has caused the oedema is the only thing, which can permanently solve the problem of oedema. However, in some situation this may be difficult in which case other supportive may have to be continued indefinitely.