Principles of Compression Therapy
The concept of compression therapy lies on a simple and efficient mechanical principle: the application of an elastic garment around the leg.
By compressing the limb with graduated compression -- strongest at the ankle and decreasing up the leg -- the compression stocking helps venous return, decreases venous pressure, prevents venous stasis, reduces edema and deterioration of venous walls, and efficiently relieves aching and heavy legs by aiding the body in moving blood up the leg.
This treatment is prescribed by a clinician to treat lymphedema, phlebitis, thrombosis, aftercare following surgery, sclerotherapy, and any other forms of varicose vein treatment. It is also prescribed to relieve all conditions of chronic venous disease (heavy legs, varicose veins, edema, and leg ulcers). It can also be prescribed to prevent venous issues during pregnancy and long distance travel. If no contraindications like severe arterial insufficiency are present, you may even buy compression stockings of lower pressure without prescription.
Depending on the pathology, medical compression therapy can be applied in different forms: socks, stockings, tights, or bandages.
The current new textures and fashion designs of SIGVARIS® compression products encourage better patient concordance due to the efficacy and comfort of the garments.
The principle of this therapy is to exert a controlled pressure on the limb. The pressure unit is the millimeter of mercury (mmHg) or the hecto Pascals (hPa). 1 mmHg = 1.33 hPa.
The pressure is exerted by the application of a device on the limb.
Stockings or bandages are called medical devices. They must meet strict requirements. The devices are called orthesis meaning that their action is to support or to reinforce a part of the human body, and not to be a substitute like a prothesis.
The action of the device is mechanical. It utilizes the principle of hysteresis that is defined by the stretch-relaxation curve of an elastic body. The transmission of the pressure to the vascular system by those devices is indirect.
The principle stands against the hyperpressure induced by a defective venous system
The pressure is stronger at ankle level. The compression device must exert a contra-pressure where the pressure level is the strongest : at the ankle.
The pressure is degressive. The direction of the blood stream must be respected. Therefore the pressure must be degressive. The gradual pressure decrease is defined in the requirements of the devices, and depends on the compression classes.
The pressure is determined by the elastic recoil force of the hosiery and the form of the leg.
- Pollack A.A. et Wood E.H. Venous pressure in the saphenous vein at the ankle in man during exercise and changes in posture. J Appl Physicl. 1949,1: 649.
- Partsch H., Rabe E., Stemmer R. Compression. Chaptre 5. In: Compression of the extremities. Editions Phlébologiques Françaises. 2000. Paris. Pages 57-134.
Effects of compression
1. Hemodynamics effect
- Increases venous blood flow
- Decreases venous blood volume
- Reduces reflux in diseased superficial and/or deep veins
- Reduces a pathologically elevated venous pressure
2. Effect on tissue
- Reduces an elevated edema of the tissue
- Increases the drainage of noxious substances
- Reduces inflammation
- Sustains reparative processes
- Improves movement of tendons and joints