Compression therapy has been widely used as a treatment modality to alleviate symptoms associated with swelling of limbs.

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When the affected area (e.g. the legs) are compressed, the increased pressure forces the blood to return to the heart. This pressure gradient also ensures there is no back flow of blood that would have been present due to the valves within the veins not closing tightly. This increase in circulation would significantly bring down swelling and reduce the pain felt by the patient.

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In the case of lymphedema, swelling is a result of the accumulation of lymph due to the local or regional failure of the lymphatic system. Hence, to reduce the swelling, the accumulated lymph needs to be moved out back into a region where the lymphatic system is working normally (John Hopkins Medical)

 

Compressions socks apply statically graded pressure distribution in the lower limbs, with the highest pressure being applied to the distal regions. In order to see any significant improvement in circulation due to the compression provided by static socks, they need to be worn for a long period, which brings about significant discomfort. However, in order to preserve this effect, the static compression garment needs to be worn throughout the day.

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Another method of applying compression to improve blood flow is the use of Pneumatic Compression Devices (PCD). These devices pump air into a bladder that inflates around the affected area thus applying pressure on to it. PCD allows the higher-pressure values to be achieved in a shorter time, reducing the overall treatment time. However, currently available PCD devices are not ergonomic; they are tethered, bulky and require the user to be stationary for the duration of the compression session.

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The external compression within the inflatable bladders could be applied axially uniformly or as a graded axial pressure gradient. When axially uniform compression is applied to the affected region, the entire region under compression is taken to a high-pressure state. Once the bladders decompress, the fluid would flow to the region of lower pressure (i.e. regions of the body that were not compressed). However, static compression is not able to fully control the direction of blood flow; for instance if the calf was the region under compression, once the pressure applied is removed there is a possibility of the blood flow increasing towards the foot as opposed to going towards the heart.

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This could be avoided using graded application of pressure. Compressing the distal region of the limb to higher pressure relative to the pressure applied at the proximal regions would ensure the fluid flow towards the required region of the body. This is achieved by sequentially pressurising the limb by use of multi chambered pressure bladders