dictionary

Edema

See also: exudate - bumps

What is Edema?

Edema is an accumulation of fluids in the interstitial spaces of the body. The most obvious symptom of this condition is the swelling which, as everyone knows, characterizes various pathologies.

A simple but objective diagnostic criterion is based on the local compression of the swelling with a finger. If a dimple is formed, called "fovea", the examination has had a positive outcome and one can speak of pathological edema. The fovea is more evident if the maneuver is performed at a bony prominence, such as the anterior edge of the tibia and the sacrum. If instead the edema is the consequence of a trauma or is caused by an accumulation of mucopolysaccharides (myxedema), typical of hypothyroidism, the tissues immediately return to the original position.

Causes

Edema can be linked to local causes (circulatory difficulties such as varicose veins of the legs, skin inflammation, etc.) or to extend to the whole organism. Kwashiorkor, a disease caused by an extremely low protein intake, manifests itself, among other things, with the appearance of diffuse edema. This aspect gives the abdomen a swollen appearance (ascites), particularly evident in malnourished children who live in developing countries.

Why do the legs swell?

From a physiological point of view, edema is the result of alterations in capillary exchange.

Under normal conditions, the capillaries tend to filter at the level of the arterial extremity and reabsorb at the level of the venous extremity. The blood that circulates very slowly inside them, can thus transfer oxygen and useful substances to the arterial end and charge itself with waste products towards the venous end. These passages are favored by a very thin pressure gradient, because it is influenced by numerous factors, such as venous pressure and the concentration of proteins in the plasma and interstitial fluid.

When we stand for a long time our feet swell. Standing means a venous pressure increase (gravity hinders the return of blood from the lower limbs to the heart). Because of this increase in blood pressure, the entire capillary tends to filter, both at the venous and arterial ends, lacking resorption and this causes the accumulation of liquids (edema). An analogous speech if a vein is occluded by a thrombus (phlebitis): the blood fails to pass, the venous pressure increases, the capillary reabsorbs with difficulty, liquid accumulates in the interstitial space and edema is formed.

All this would occur much more often than when it actually happens, were it not for the action of the lymphatic system, responsible for the reabsorption of the interstitial fluid present in excess. An inadequate lymphatic drainage can in turn be responsible for edema and swelling (for example due to parasites, the growth of tumors, the removal of lymph nodes or the growth of fibrous tissue consequent to radiation therapy).

Arterial hypertension, on the other hand, does not cause edema, as it is regulated by the arterioles that are upstream of the capillary.

Another cause of edema is heart failure . If one of the two ventricles cannot pump all the blood that comes from the other, the blood accumulates in the systemic or pulmonary circulation. Again, there will be an increase in venous pressure, filtration will exceed resorption and edema will occur. Renal failure, on the other hand, causes edema because the kidneys are unable to perform an effective filtering action and there is a loss of protein in the blood.

Malnutrition, a strongly hypoproteic diet or the dietary and metabolic changes induced by alcoholism, as seen for Kwashiorkor, decrease the concentration of proteins in the plasma. Since these proteins invoke water generating a pressure, called colloidosmotica, the decrease in their plasma concentration reduces capillary reabsorption, causing edema. Also liver failure (in particular cirrhosis ) leads to the same pathological manifestation, as the liver is the main site of synthesis of plasma proteins.

Finally, edema is a typical consequence of inflammation, which can arise from agents of a physical nature (trauma, heat), chemical (acid, etc.) or biological (bacteria, viruses, etc.). Because of the lesion and some microcirculation changes induced by the inflammatory response, there is an increase in capillary permeability, with consequent accumulation of proteins in the interstitial fluids (present in the extracellular space, ie between the capillary and the cell). Similar to what was seen for malnutrition, there is a decrease in plasma colloid-osmotic pressure and an increase in filtration at the level of the capillaries. Once again the result is the appearance of edema.

Care

Edema is cured by addressing the disease that generated it.

To learn more about each topic, see: physiology of the capillary circle and varicose veins. For natural remedies: horse chestnut, centella, blueberry, butcher's broom and natural diuretics.