Pitting Edema Causes And Treatment: Edema Formation Mechanism

Edema is a swelling caused due to accumulation of the fluid (water) in the interstitial space or serous cavities. The space between the skin and soft tissue in the body is called interstitial space. Edema becomes evident only when there is huge collection of fluid in the tissue space. At least 5 to 6 liters of water or fluid accumulate in the water depots.

Edema can be of two types, non-pitting edema and the pitting edema.

In pitting edema, there is a pit or a depression left for some time after applying pressure with a finger on the affected part, generally on the limbs. Pitting on pressure occurs when the circumference of the limb is increased by 10%. In non pitting edema, there is no depression left behind after applying pressure. Pitting edema can occur in a specific local area, for example in left lower leg. It can also be generalized, meaning it may involve the whole body.

Mechanism Of Edema Formation

In normal circumstances water is present in the cells and outside the cell in the interstitial space and the blood vessels.

Constant exchange of fluid takes place between the intravascular and extra vascular compartments. This physiological process maintains the equilibrium of fluid in the body. However, when there is an imbalance in this equilibrium, fluid accumulates in the interstitial space. Following factors are responsible for Edema:

  • Increased permeability of tiny blood vessels called capillaries as a result of their damage. Example: Acute inflammation.
  • Increase of pressure inside the capillaries. Example: heart failure.
  • Decreased osmotic pressure of the blood. Example: hypoproteinemia meaning low level of blood protein.
  • Damage of lymph vessels.

Edema generally occurs as a result of retention of salt in the body. In order to compensate excess of salt, body retains more water which gives rise to swelling in the interstitial space. In normal circumstance, people may suffer from mild pitting edema when they stand for long hours in one place, or in hot weather, in pregnancy.

However, serious illnesses can also cause pitting edema. In fact many times it becomes an indicator for the patient that something is wrong in his body and he needs a doctor’s consultation. Several ailments can cause pitting edema, such as

Causes Of Pitting Edema

Cardiac causes:

  • Congestive cardiac failure: pitting edema is present in most dependent part of the body. Hence if the patient is ambulatory, pitting edema is present in the ankles, foot, and legs. If the patient is lying down or recumbent, edema is generally present at the back and in the genitals.
  • Left ventricular failure: here the fluid gets accumulated in the lungs much earlier than in the limbs, giving rise to breathlessness, cough and peculiar type of sound while breathing.

Kidney causes:

In kidney disease, the pitting edema is generalized and not limited to the dependent parts of the body. It is more noticeable on the face and around the eyes. The cause of such edema is due to disturbance of water and salt excretion. Even low serum protein is responsible for renal edema.

Liver disease:

Cirrhosis of liver damage leads to abnormal function of the liver. As a result, fluid gets collected in the abdomen giving rise to a condition called Ascites. Ascites causes pressure on the veins which leads to pitting edema of legs.

Several other causes which can give rise to pitting edema are: inferior vena cava obstruction, nutritional deficiency, sudden stoppage of diuretic, polyarthritis, angioneurotic edema, gout, venous thrombosis, premenstrual fluid retention, infection such as a boil, cellulitis, pregnancy induced hypertension, intake of certain drugs such as NSAID, calcium channel blockers, Vasodilators, liquorice, estrogen, trauma etc.

Pitting Edema Treatment

The therapeutic goal of treating pitting edema is to mobilize the interstitial fluid and thereafter maintain equilibrium in fluid inside and outside the cells.

In most cases, treating the underlying cause which is triggering the development of pitting edema may reduce the swelling. If the cause is temporary, pitting edema will recede permanently after the cause is treated.

However in chronic condition, edema may often come back after initial cure. In many cases physician prescribe low dose of diuretics. Diuretics are drugs that cause excess of urine.

If the cause is venous blockage medications are given to dissolve the blockage and sometime surgery may be necessary.

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