Compression therapy - what is it and why use it?

Compression stockings and support hosiery are the simplest form of compression therapy - squeezing your legs to improve the flow of blood up your veins.

An analogy is a river in a narrow gorge then out onto a delta. The same amount of water is flowing in both parts in a given time, but it has to speed up greatly to all get through the gorge in that time.

Squashing your leg veins flat with compression, speeds up the blood flow, reducing the risk of clotting during a bus or plane trip.

It is possible that it also approximates the leaves of valves in stretched varicose veins, allowing them to work again.

Our veins have valves to prevent backflow, which break up the column of blood returning to our heart from our legs. The pressure at the bottom of a 4ft column of blood is considerable and would make it hard to prevent oedema fluid leaking out under our skin.

Oedema of the feet and ankles in fit military men during a voyage on a troopship, was called deck oedema. The was little room to sit down on the crowded ships. Even prolonged sitting will cause this, and without adequate movement compression therapy is less effective¹.

Our calf muscle pump has a big effect on the return of blood from our legs.

Wearing compression to reduce oedema, it is still important to use your calf muscles if you can. This means using your foot plus toes, with spring in your step. Calf muscle stretching may be a first step, as adequate ankle movement is needed to allow one to do this.

Swollen legs may be a sign of serious kidney, liver or heart disease. Blood tests, chest X-ray and echocardiography may be needed.

Safety aspects - assessment of leg arterial blood supply²

"Before compression therapy is commenced, thorough vascular assessment to exclude significant peripheral arterial disease is essential.
If foot pulses are weakened or absent, an ankle/brachial pressure index should be calculated.
Divide the ankle systolic pressure of the dorsalis pedis or posterior tibial artery (the greater value taken as the ankle pressure) by the brachial systolic pressure.

If the patient has arteriosclerosis or diabetes, it is imperative that a great toe pressure index (photoplethysmography) also be performed."

This is to ensure that you don't have the blood supply to your leg cut off by the bandages - fairly important. This assessment is done by properly trained and equipped professionals, when it is thought necessary.

Systolic is the top reading of the blood pressure, with each beat of the heart. Diastolic is the bottom reading just before the next beat (pressure wave) comes through.

If the ankle-brachial index is greater than 0.8, compression is considered safe.

References

2. Vicaretti M Compression-therapy for venous disease Australian Prescriber 33(6) Dec 2010
http://www.australianprescriber.com/upload/pdf/articles/1151.pdf
This pdf is a complete review including good illustrations.

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