Abstract
Background
The terminology in compression therapy is not always consistent. Confusion arises from layers, components, materials, whether elastic or inelastic, stiff or not stiff, compression class, and other terms. The aim of this paper is to define a standard terminology for compression therapy.
Method
the International Compression Club (ICC) board members prepared a draft consensus paper, which was circulated among the ICC members and refined by GM according to the comments and suggestions received.
Results
All the terms used in compression therapy, from the definition to the materials, compression kits or systems, their physical properties, compression pressure, compression characteristics, and components and layers, were considered and agreed upon.
Conclusions
The given definitions allow for consistent classification of compression materials or devices. The International Compression Club hopes that the proposed terminology will be widely accepted and that papers and congress presentations on compression will use precise terminology.
Introduction
Compression therapy (CT) is widely used worldwide and is often reported in publications and meeting presentations. Unfortunately, the terminology used in papers and presentations is not always consistent. Therefore, it is recommended that proper terms be uniformly and widely accepted.
This paper aims to report a consensus among International Compression Club (ICC) members on the correct terms regarding CT.
Method
The ICC board members prepared a draft of this consensus paper, which was circulated to all ICC members. They returned comments and suggestions that were integrated into the document by GM. The final document was agreed upon and approved by the ICC board members.
Results
A general agreement was reached on the following terms and definitions.
Compression therapy consists of applying a compression device around a body segment to exert external pressure
It can treat symptoms and signs of chronic venous disease, lymphedema, lipedema and vascular malformations. It can also be used in other indications such as muscle trauma, contusions, sprains, tendon injuries, joint dislocations, Baker cyst rupture. 1
Compression material: Every material that can be used to apply a compression therapy
Physical properties: compression materials can be classified as elastic or inelastic. 2
The elastic material is characterized by the ability to regain its initial length after stretch release
Elastic material contains elastic fibers and can be long stretched (elongation >100%). For this reason, it is also called long stretch. It gives way to muscle expansion when standing or walking. Its static stiffness index (SSI) is < 10 mmHg. Elastic bandages and medical compression stockings are typical elastic materials.
The inelastic material has no elastic fiber in the textile
It can be non-stretchable (zinc paste bandage) or slightly stretchable (short-stretch). Depending on its hysteresis curve, the material may or may not return to its initial shape after being deformed. Inelastic material does not give way to muscle expansion (the leg gives way). Its static stiffness index (SSI) > 10 mmHg. Non-stretch or short-stretch bandages, adjustable compression wraps, and pumps are typical inelastic materials.
Medical compression stockings: Compression garments knitted with elastic material
1. “Standard” or round knit stockings are produced seamlessly and spirally by a circular knitting machine. They can be ready-to-wear to fit multiple leg sizes or made-to-measure in case of dysmorphic legs. They are classified according to the exerted pressure but this classification is different in different countries. For instance, a stocking exerting 20 mmHg is class 1 in German-speaking countries and in Italy but ti is class 2 in France and in England. Therefore, we suggest defining elastic stockings only by their exerted pressure and not by classification. These stockings are used mainly in patients with venous disorders. 2. Flat knit stockings: they are knitted in a row with a flat knitting machine and need to be sewn in their posterior part to be worn. They come in ready-to-wear or can be made-to-measure, specifically prepared for a single patient to fit his/her leg perfectly. These stockings are mainly used in patients with lymphedema and lipedema but also in patients with venous disease with dysmorphic legs. 3. Support stockings or thrombo-embolic deterrent (TED) stockings have no defined pressure distribution; the dose of compression is expressed in deniers or as light, medium, or strong. Finally, the exerted pressure is not guaranteed. These stockings cannot be considered medical products because they do not have the properties of medical aids. They are usually prescribed to people with healthy veins to prevent occupational edema or deep vein thrombosis.
Hosiery kits or elastic kits: Kits made up with a liner and an overstocking
They are used on top of each other and provide pressure according to their defined compression class.
Compression bandages: A strip of stretchable textile that can be wrapped around the leg/arm/midline region
They can be made of elastic or inelastic material.
Adjustable compression wraps or simply wraps: Compression sleeves made with inelastic material (non-stretch or short-stretch) applied around a leg or arm and closed by hook-and-loop fasteners
The term adjustable compression comes from its ability to exert different compression pressures according to the stretch given to the fasteners.
Compression device or compression system: Has to be used when different materials are applied together
For example, composite bandages, including padding materials. Wraps are also defined as devices.
Intermittent pneumatic compression (IPC) is a compression modality exerted by a pump device
A sleeve with a built-in air bladder covers a body segment. It is provided with a pump that inflates the bladder at a preset time and pressure. The sleeve can cover only the foot, the foot with the calf and the thigh, or the arm and the hand.
Compression or interface pressure: The pressure exerted by a compression material/device
It can be measured in the laboratory and in vivo at the interface between the compression material and a limb experimental model or between the compression material and the skin.
3
Pressure values are provided in millimeters of mercury (mmHg). i. Resting pressure (also called supine pressure): the interface pressure at rest in the supine position with complete muscular relaxation. ii. Working pressure (also called standing pressure): the interface pressure in a standing immobile position. iii. Pressure peaks: the pressure peaks during muscle activity. iv. Compression pressure measuring device (or instrument): device (or instrument) to measure the compression pressure.
The most widely used are based on pneumatic or piezoelectric technology. v. B1: the site for measuring the compression pressure in the lower leg.
A consensus stated that the compression pressure in the leg must be measured, at least, at B1, the medial area where the gastrocnemius tendon turns into the calf muscles (usually about 10–15 cm above the medial malleolus). Even when measured at other leg points, the measurement at B1 cannot be missed to obtain consistent data. There are no recommended measuring locations for the thigh or arm.
Compression characteristics
i. Elastic power: the force of an elastic material to return to its original length after the stretch is released.
Elasticity was already defined as the property of a material to return to its original length after stretch removal. The force of the elastic material to regain its initial length is the elastic power, which depends on the number of elastic fibers in the thread and the amount of stretch given to the bandage: the more the elastic fibers and the stretch, the stronger the elastic power. ii. Stretch/Elongation: the ability of a compression material (specifically bandages) to be extended or stretched to its maximum.
Based on this characteristic, compression materials are distinguished as non-stretchable (elongation<10%), short stretch (elongation between 10 and 100%), or long stretch (elongation >100%). iii. Hysteresis: the loss in the ability of a compression device to recoil to its original length after exposure to repeated stretch-relaxation maneuvers. iv. Stiffness is the pressure increase produced by a compression material or device per 1 cm increase in limb circumference.
The definition comes from the European Committee for Standardization (CEN) for medical compression hosiery.
4
It can be defined as an elasticity coefficient. v. Static Stiffness Index: the difference between the standing and the resting pressure.
5
When calculating the static stiffness index (SSI), we conventionally assume that the calf circumference increases by 1 cm moving from the supine to the standing position. 10 mmHg is the cutoff between elastic and inelastic material. Actually, the calf circumference never increases by 1 cm when standing up. However, the contraction of the junction between the gastrocnemius tendon and muscle reduces the radius of this area, increasing the pressure according to the Laplace law.
6
The SSI is a valuable parameter for characterizing the elastic properties of compression materials. The dynamic stiffness index (DSI) and walking pressure amplitudes (WPA) are used for the same aim. However, DSI and WPA are used less and, consequently, are less reported in the literature and less supported by clinical evidence/relevance. vi. Dynamic Stiffness Index (DSI): the difference between the maximal and minimal interface pressure during maximal foot dorsiflexions in the supine position or tiptoeing.
The calculation of a dynamic stiffness index previously described
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is so complicated that it can be measured only in the laboratory by very complicated instruments. We proposed a simplified calculation of the dynamic stiffness index. 20 mmHg is the cutoff between elastic and inelastic material. vii. Walking Pressure Amplitude (WPA): the difference between the maximal and minimal interface pressure during walking or walking on the spot.
Ten mmHg is the cutoff between elastic and inelastic material.
Compression components: compression therapy can be exerted by a single component or multiple components (compression devices or compression kits)
i. Single component: compression is exerted by only one material. ii. Multiple components or multi-component: compression is exerted by more than one component forming a kit.
All the components can be elastic or inelastic. A combination of elastic and inelastic materials is also possible. Multicomponent compression devices are usually called multilayer. This is a mistake. For instance, some compression systems are traditionally called two-layer while they are made up of two components. Similarly, another compression system is traditionally called “four-layer” while it comprises four components and should be, more appropriately, called “multi-component.” They are applied in multiple layers, indeed more than two or four, respectively. Additionally, superimposing different components changes the properties of the final bandage as the friction between several layers comes into play, changing its elastic properties. Consequently, the so-called “four-layer,” comprising four elastic bandages, is characterized by an SSI >10 mmHg in the inelastic range. 8 Therefore, the terms elastic and inelastic should be restricted to the single compression component. Stiff or non-stiff are the proper definitions for multicomponent bandages. However, in the daily language, inelastic and stiff and elastic and non-stiff are considered synonyms.
Layers: Compression materials/devices can be applied as single or multiple layers
i. Single layer: just one layer is applied.
A single layer is only possible with elastic stockings. ii. Multiple layer or multilayer: compression material or device applied in more than one layer.
All the bandages are multilayer. It is just enough to superimpose the turns of a single bandage by 50% and we will already have two layers. When superimposing a single bandage by 60%–70%, the bandage can result in three layers. The result will be four layers by applying one bandage in figure-of-eight mode. In conclusion, all of them are single component/multilayer, and the term multilayer compression is incorrect and could be avoided when referring to bandages.
Summary of compression terms.
Discussion
A common language is always requested in the scientific literature and during scientific presentations so that misinterpretations cannot occur. Some terms, commonly used incorrectly in published papers and meetings, led the ICC members to refine compression terminology. Just to give some examples: - In many countries, compression therapy is mistakenly called elastic compression,9,10 when the correct term is compression therapy. Elastic compression is just one kind of compression therapy that also includes materials exerting inelastic or stiff compression. - Elasticity and long stretch are usually confused. However, elasticity refers to a material’s ability to regain its initial length when stretch is released, while long stretch refers to its specific elongation property. - The terms multilayer and multicomponent are often used as synonyms.11,12 However, all bandages are multilayer and can be classified as single components or multicomponents. Therefore, we suggest eliminating the term multilayer when speaking about bandages that will be classified only as single components or multicomponents. The terms two-layer, three-layer, and four-layer should be abandoned because these multicomponent bandages are applied in many more than 2,3 or four layers.
If all the terms are accepted, everybody will use the same language and understand what we are speaking about.
Below are some examples of correct definitions of compression devices. However, based on the proposed suggestions, all compression devices can be consistently classified. Regarding bandages, one can wonder what “when correctly applied” means. We believe a bandage is correctly applied when wrapped according to the manufacturer’s instructions. • Medical compression stockings: single-component, elastic stocking exerting a supine pressure between 10 and 50 mmHg. • Hosiery (or elastic) kit: multicomponent, non-stiff (or elastic) kit, exerting a supine pressure of around 40 mmHg. • Rosidal®K, Putter binde®, Comprilan®: single component, inelastic bandage exerting a supine pressure ≥40 mmHg when correctly applied. • Profore®: multicomponent, stiff (or inelastic) compression device (or system) exerting a supine pressure ≥40 mmHg when correctly applied. The term multilayer is pleonastic and should be eliminated. • Urgo K2®: multicomponent, stiff (or inelastic) compression device (or system) exerting a supine pressure ≥40 mmHg when correctly applied. The term multilayer is pleonastic and should be eliminated. • Urgo K1®: multicomponent in a single bandage, stiff (or inelastic) compression device (or system) exerting a supine pressure ≥40 mmHg when correctly applied. The term multilayer is pleonastic and should be eliminated. • Rosidal sys®: multicomponent, stiff (or inelastic) compression device (or system), exerting a supine pressure ≥50 mmHg when correctly applied. The term multilayer is pleonastic and should be eliminated. • Wraps: single-component, stiff (or inelastic) compression device exerting a wide supine pressure range depending on the stretch of hook-and-loop straps. Some devices are provided with an undersock, tubular bandage, or cover-up, which will be classified as multi-component. • Intermittent pneumatic compression: stiff (or inelastic) compression device exerting programmable uniform or sequential compression pressure and compression intervals.
Conclusions
We intend to provide common terminology for all involved in compression therapy to report their experience and data in the English literature.
All publications evaluating these compression systems should systematically report on the above-mentioned terms: the single-component or multi-component system, its supine and standing pressure, its stiffness, and all the other necessary details.
We hope the scientific community will accept this consensus, making compression therapy terminology more precise.
Footnotes
Author contribution
Giovanni Mosti Contributorship: All the authors contributed to preparing the first draft of thedocument. GM received the inputs from the ICC members and refined the document that all the authors then approved
Declaration of conflicting interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
