What Causes Lymphedema In The Obese?
Obesity should be considered an aggravating factor when there is lymphedema because it makes more difficult the lymphatic and venous return, weight control, measurement of the affected limb, physical activity, skin care and correction of diseases such as phlebitis, diabetes, hypertension, heart or kidney disease which are related to it.1
Lymphedema management in the obese consists of a correct prevention and adequate treatment. It is important to perform early detection of patients with risk of lymphedema and provide appropriate instruction about the state of nutrition. since obesity should be considered an aggravating factor when there is lymphedema because it makes more difficult the lymphatic and venous return, weight control, measurement of the affected limb, physical activity, skin care and correction of diseases such as phlebitis, diabetes, hypertension, heart or kidney disease. The patient should be informed that after lymph node dissection or radiotherapy surgery, patient may develop lymphedema within 15 years after the surgery, therefore the “risk” members should be carefully observed.2
Edema can be defined as the accumulation of liquids in tissues. Depending on the pathologies that occur in the body, there are several mechanisms that can trigger an edema. An increase in capillary pressure, either due to an increase in venous pressure, blood pressure or obstruction of the venous system, can cause edema. On other occasions, the edema will be caused by a decrease in the colloid osmotic pressure of the plasma, as happens in all those circumstances in which the concentration of plasma proteins decreases.
But what happens in the lymphatic system? How does it participate in the production of edema? Experts establish a series of concepts that allow us to understand the participation of lymphatics in the development of edema.3 Thus, they understand as lymphatic protein load to the amount of extravascular plasma proteins that are supposed to be reabsorbed by the lymphatics in the unit of time. On the other hand, it refers to the lymphatic aqueous load, to the amount of water that leaves the blood capillaries by filtration and direct reabsorption in the bloodstream. Based on these principles, experts establish two fundamental groups of lymphatic insufficiency: dynamic insufficiency and mechanical insufficiency.
Dynamic insufficiency of the lymphatic system would occur when the carrying capacity of the lymphatic load is exceeded. This occurs for example in venous edema.
In the mechanical insufficiency of the lymphatic system, the cause is an obstacle that prevents the reabsorption of the lymph, which brings as a consequence a deficiency in the function and capacity of the lymphatic collectors with the consequent increase of the intralymphatic pressure, dilation of the vessels and valvular incompetence. In this situation we find a rich in proteins lymphedema.
Within this mechanical insufficiency two circumstances can occur: that the cause is an alteration of the lymph nodes and / or vessels or that there has been a decrease or abolition of the carrying capacity of the lymph. When an obstruction of the lymphatic vessels occurs, the organism puts into operation those compensatory mechanisms to supply this obstacle.
The most frequent causes of mechanical insufficiency are produced by organic alterations of the vessels and lymph nodes.
The primary lymphedemas with their variants of dilatation, hypoplasia or aplasia of the lymphatic collectors along with the lymphedemas secondary to inflammatory processes, surgery, radiation, neoplastic processes, etc. are undoubtedly the main exponents of mechanical lymphatic insufficiency.4
The mechanisms of edema production include an increase in capillary filtration and a decrease in interstitial fluid reabsorption.
The causes of increased capillary leakage are increased hydrostatic pressure, decreased tissue pressure, and increased permeability of the capillary membrane. The reduction of the interstitial fluid absorption may be due to the reduction of the plasma oncotic pressure or the lymphatic obstruction.5
The function of the lymphatic system is to take back the excess of fluid and proteins that are in the interstitial space towards the blood vascular system. When the lymphatic system is damaged or blocked, it does not function properly in its absorption (it is considered that for a man or woman of 60 Kg, 3 liters of fluid filter from the blood vessels to the tissues and is normally captured by the lymphatic system). If the patient is obese, the situation gets harder.6