What do compression stockings do?

The pressure necessary for the stockings to comply with an adequate compression will depend on the support material used and the surface on which they act. Both, complying with some physical principles, must allow the stockings to exert a balanced pressure capable of compensating for disorders caused by failure of venous or lymphatic circulation, without altering arterial circulation.

Compressive therapy applied should influence venous volume, the spacing between venous valves leading to reflux, venous capacitance, venous drainage speed, and their return time.

Differences between graduated compression stockings and those that are not

Unlike traditional stockings and non-compression sports socks, graduated compression stockings use stronger elastics, especially fabrics to create significant pressure on the legs, ankles, and feet.

Compression stockings are orthotics and aesthetic stockings are not. An orthosis is an external device that is applied to the body to modify its functional or structural aspects, which in the case at hand seeks to promote flow in the venous and lymphatic system both at rest and in activity.

The law governing the operation of graduated stockings

Compressive therapy will exert greater pressure on the ankles – the area most affected by venous hypertension – thanks to the fact that this is an area with a smaller perimeter (and therefore less radius) than the rest of the limb.

It should be noted that the ankle does not exactly have a circular shape, therefore when we speak of “ankle radius” it is an approximation that allows us to approach a useful mathematical model rather than an exact mathematical reality.

If we follow the Law of Laplace we will see that with surface tension a zone with a smaller radius will receive greater pressure thanks to the fact that this reduction in radius will have less influence on the force of the surface tension exerted (Laplace’s Law: Pressure = Tension / radius). Conversely, increases in radius versus constant tension lead to a decrease in pressure. This explains that in the lower extremities, the lower the stockings are, the more pressure they exert because the radius of the segment is progressively reduced, which is very good to fight against the increased pressure inside the veins that would otherwise be very high.

Dynamic Effects of Stockings During Exercise

The compression stockings due to their characteristics exert different pressures (cyclical gradients) in the situations of rest or muscle contraction associated with their adaptability by stretching and subsequent elastic recovery.

In this way, an active compression is generated by variation of muscle volume during exercise and a passive compression, and also therapeutic, during rest.

Effects on tissue adjacent to veins

The compression exerted by the stockings is greater in the skin tissue, more superficial, and decreases towards the deep tissue.

The reduction of edema (swelling) through compression stockings, as long as it is not excessive, will facilitate perfusion from the capillary, thereby favoring the nutritional supply of the limb.

Analysis of the arterial supply condition prior to the indication of elastocompression

Given the importance of the nutritional supply of the limb, it is necessary before indicating compression stockings to know the state of arterial perfusion, evaluating the presence of distal pulses, which can be supplemented if necessary with perfusion studies. In general, when there is a relationship between ankle and arm pressure (called the ankle-arm ratio) equal to or above 0.8, compression therapy is not expected to cause problems with arterial flow.

CONCLUSION

In summary, with the use of graduated compression stockings, the following is pursued:

• They counteract high venous pressure by reducing it from distal to proximal.
• Reduce the diameter of the superficial veins.
• Increase the velocity of venous blood in the lower extremities by reducing stasis.
• Restore or improve valve function.
• Control edema.
• Improve the function of the vein wall and act on coagulability.
• Improve the patient’s conditions that will lead to improving their quality of life.