BLOG 5 Compression bandages

Therapeutic compression bandaging is a very important topic and the subject of much debate within the health sector. In the previous blog post, we discussed bandage elasticity, and as we will see in this post, compression is one of the physically measurable parameters that characterize the elastic behavior that governs medical compression.

What is compression?

The dictionary tells us that compression is “pressure to which a body is subjected by the action of opposing forces that tend to reduce its volume.” If we apply this to the case of bandages, we are talking about the active action exerted by a bandage when it is applied to a limb by means of the action of the professional who performs the bandaging and/or the compression of the bandage itself.

In this definition can be found another basic concept necessary to understand bandage compression, which is that compression can be generated in two different ways: first, there is the compression generated by the health professional when applying the bandage and, second, the compression produced by the bandage itself due to the composition of its yarn.

If a health professional applies a compressive bandage that is not very elastic, but exerts pressure when doing so, this bandage will be a compression bandage where the pressure is exerted by the health professional.

If a health professional applies a bandage using hardly any pressure and stretching the bandage only 25%, with a bandage made of elastic and compressive yarn, the bandage will generate compression as time goes by because it will try to return to its initial length and will compress the bandaged area.

As we have seen, we are analyzing two very different bandages, but both generating compression.

While compression can be achieved with any type of bandage, if what we are looking for is a therapeutic effect, we must pay attention to two aspects. On the one hand, there are the laws of physics that govern it, such as Laplace’s Law (interface pressure) and Pascal’s Law (transmission of pressure to the subcutaneous tissue), which we will discuss in later blog posts. And on the other hand, there are the parameters that control it, such as elasticity, hysteresis and stiffness, which we will deal with in a very general way in this post.

Parameters governing medical compression

Compression in bandages is determined by the three parameters that govern it: elasticity, hysteresis and stiffness.

Figure 5.1 Triangle of properties governing medical compression (hysteresis, elasticity and stiffness)

First there is elasticity, which is considered a parameter within that of compression, as well as one of its properties already discussed in previous blogs. We will not dwell too much on elasticity here, but simply mention that it is the ability of a bandage to stretch and return to its normal position. This should not be confused with saying that an elastic bandage generates compression. An elastic bandage may or may not generate compression; greater elasticity does not necessarily mean greater compression, nor the opposite.

The next key property is hysteresis. In clinical terms, hysteresis is the ability of the bandage to return to its initial elongation once it has ceased to undergo the stimulus that generated its stretching. This parameter is also known as “rebound or resilience”.

In relation to hysteresis, Professor Partsch refers to it as a measure of the loss of energy that occurs between loading (stretching) and unloading (relaxation). Yarns with minimal hysteresis are the best because they have maximum holding power with minimal resistance to stretching.

Figure 5.2 Hysteresis curves of different bandage materials

As can be seen in Figure 5.2, to achieve the same level of pressure on the leg (blue dashed line), elastic bandages (right) need more stretch than inelastic bandages (left). At the same time, highly elastic bandages have a higher hysteresis than less elastic bandages. This means that inelastic bandages, when you exert force and then stop exerting force, behave the same and stretch the same. This symmetrical behavior is positive when it comes to therapeutic compression treatments.

Finally, there is the property of stiffness. When we talk about stiffness in compression bandages, it refers to the resistance of the bandage itself to lengthening or shortening when the muscular volume of the compressed area increases. An example would be the case of venous ulcer bandages where the stiffness would be the resistance of the bandage to stretching when the calf muscle increases in volume when walking, or with exercise.

Produced by the Technical Department of Calvo Izquierdo S.L.

With the collaboration of Carmen Alba Moratilla.

 

Bibliography:

– https://dle.rae.es/compresi%C3%B3n

– Partsch H, Rabe E, Stemmer R. Compression therapy of the extremities. Paris: Editions Phlébologiques Françaises; 1999.) (1) (2)

– A. Coull, D. Tolson, and J. Mcintosh. Class-3c compression bandaging for venous ulcers: comparison of spiral and figure-of-eight techniques. Journal of Advanced Nursing, 54(3):274–283, May 2006

– Partsch, Hugo. (2014). Compression for the management of venous leg ulcers: Which material do we have? Phlebology / Venous Forum of the Royal Society of Medicine. 29. 140-145. 10.1177/0268355514528129

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