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Advanced textiles for wound compression
6 Advanced textiles for wound compression S. R A J E N DR A N and S. C. A NA N D, University of Bolton, UK
Abstract: The application of compression textiles in managing venous leg ulcers is discussed. The classification of compression bandages, merits and limitations of the current compression therapy regimen, and the research into the development of novel orthopaedic padding and compression bandages are highlighted. The role of compression therapy in the treatment of oedema, varicose veins and deep vein thrombosis (DVT) is outlined. Research and development of a novel single-layer 3D spacer bandage, which replaces the existing multilayer bandage regime, is discussed. Key words: wound, venous leg ulcer, padding bandage, compression bandage, 3D spacer bandage.
6.1
Introduction
It has been predicted that there is a substantial market potential for advanced wound dressings. The woundcare industry generated between US$3.5 and 4.5 billion for the period from 2003 to 2006, mostly from the US and Europe. The European advanced wound management market was valued at US$544.4 million in 2004 and is expected to grow by an average of 12.4% a year to US$1.23 billion in 2010. The forecast for annual growth is between 10 and 15% in 2012. An ageing population creates an increased demand for ulcer treatment. The pressure ulcer treatment accounts for 4% of the National Health Service (NHS) annual budget. The annual cost of treating diabetic foot ulceration accounts for 5% of the total NHS budget. The treatment of venous leg ulcers creates considerable demands upon healthcare professionals throughout the world. The total cost to the NHS for venous leg ulcers treatment is about £650 million per annum, which is 1–2% of the total healthcare expenditure. Costs per patient have recently been estimated to be between £1200 and £1400. In the US, venous leg ulcers affect 3.5% of people over the age of 65 and the estimated annual cost is from $1.9 to $2.5 billion. In the EU, the annual cost for treating patients with venous leg ulcers accounts for 1–2% of the overall healthcare expenditure. In Australia, around 1% of the adult population suffer from venous ulceration. 153
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Venous ulcers are the most common type of chronic leg ulceration. Chronic ulcers are defi ned as those lasting six weeks or more.1 In the UK alone, about 1% of the adult population suffers from active ulceration during their life time. 2 Approximately 400 000 patients have the initial symptoms of leg ulcers and 100 000 have open leg ulcers that require treatment. 3 About 80% of patients who have leg ulceration suffer with a venous ulcer. Some patients may have more than one episode of venous ulceration with estimated recurrence rates ranging from 6 to 15%.4 The prevalence of leg ulcers increases with age affecting 1.69% of patients aged between 65 and 95 years. The incidence rate for patients in this age group is estimated at 0.76% for men and 1.42% for women. 5 It has been established that compression therapy, by making use of compression bandages, is an efficient treatment for healing various leg ulcers, despite surgical strategies, electromagnetic therapy and intermittent pneumatic compression.
6.2
Elastic compression bandages
Bandages can be used for many purposes and include retention, support and compression: • Retention bandages are used to retain dressings in the correct position. • Support bandages provide retention and prevent the development of a deformity or change in shape of a mass of tissue due to swelling or sagging. • Compression bandages are employed mainly for the treatment of leg ulcers and varicose veins. Elastomeric compression bandages made with rubber were fi rst used in the late 19th century. However, these have now been replaced by lighter, stronger, more comfortable and washable bandages made from Lycra or other elastane fibres. Modern bandages are either woven or knitted and are designed to provide prescribed levels of compression in accordance with specified performance-based standards (Table 6.1).
Table 6.1 Types of bandages Bandage
Commercial name
Remark
Retention bandage
Slinky®, Stayform ®, K-Band ®, Easifix®, Slinky®, Crinx®, Tensofix® Crepe BP®, Elastocrepe ®
Exerts very little pressure on a limb
Support bandage
Prevents formation of oedema and supports joints
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Table 6.1 Continued Bandage
Commercial name
Compression bandages Light compression (3a)
J-Plus ®, K-Crepe ®
Moderate compression (3b)
Veinopress ®, Granuflex adhesive Compression ® Setopress ®, Tensopress ® Surepress ® Bilastic Forte ®, Blue line webbing ® Zincaband ®, Tarband ®, Quinaband ®, Icthaband ®
High compression (3c) Extra high compression (3d) Paste bandages
Tubular bandages Elasticated Foam padded
6.3
Tubifast®, Tubigrip ® Netelast® Tubipad ®
Remark Exert various pressure, according to the type on a limb Gives sub-bandage pressures of 14– 17 mm Hg at the ankle Sub-bandage pressures 18–24 mm Hg 25–35 mm Hg
Up to 60 mm Hg Woven cotton fabric impregnated with a medicated cream or paste. Used for the treatment of eczema and dermatitis Dressing on awkward sites Provides padding and protection against physical damage
Venous leg ulcers
6.3.1 Venous leg ulcers: problem It is important that the arterial and venous systems should work properly without causing problems to blood circulation around the body. Pure blood flows from the heart to the legs through arteries taking oxygen and food to the muscles, skin and other tissues. Blood then flows back to the heart carrying away waste products through veins. The valves in the veins are unidirectional which means that they allow the venous blood to flow in an upward direction only. If the valves do not work properly or there is not enough pressure in the veins to push back the venous blood towards the heart (chronic venous insufficiency, CVI), the pooling of blood in the veins takes place and this leads to higher pressure on the skin. Because of high pressure and lack of availability of oxygen and food, the skin deteriorates and eventually the ulcer occurs. The high venous pressure causes oedema followed by tissue breakdown. The initial indications of venous leg ulcers
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are oedema, swollen veins (varicose veins), stasis eczema, fibrosis, lipodermatosclerosis, atrophie blanche, ankle flare and blood clots in veins (deep vein thrombosis, DVT). DVT is a growing problem for passengers on longhaul fl ights. DVT blocks blood from flowing towards the heart. Venous ulcers appear in the gaiter area of the lower limb between the ankle and mid-calf. They can vary in size ranging from very small to large ulcers that extend beyond the gaiter area. The wound is characteristically shallow, irregular in shape, and has sloping well-defi ned borders. Typically, the skin surrounding the wound is thickened and hyperpigmented indicating lipodermatosclerosis.6 With chronic ulcers a yellow– white exudate is observed signifying the presence of slough. A shiny appearance indicates a fibrinous base, which inhibits new tissue formation and wound healing. Varicose veins and ankle oedema often accompany a venous ulcer.7 Approximately 80% of patients who have a venous leg ulcer suffer from some form of discomfort, while 20% experience severe or unremitting pain. 8
6.3.2 Diagnosis of venous leg ulcers The diagnosis of lower limb ulceration must start by determining the patient’s full clinical history together with a physical examination of the condition. It is essential to identify possible risk factors that could cause ulceration or impact on the treatment of the ulcer. These risk factors could include arterial disease, trauma and malignancy.9 A number of non-invasive test methods are available to the clinician for investigating the cause of leg ulceration and venous insufficiency. These test methods help to assess the arterial and venous circulation of the patient and can provide information on the location of blood reflux or an obstruction within the veins. Doppler ultrasonography Doppler ultrasonography is used to measure the ankle-to-brachial blood pressure index (ABPI) of the patient. The ultrasound technique produces a signal that identifies the presence of blood flow within the arteries. The ABPI is obtained by measuring the systolic blood pressure within the dorsalis pedis or posterior tibial artery of the lower limb and the ipsilateral brachial artery of the arm.10 The ratio between the ankle systolic pressure and the brachial systolic pressure provides the ABPI value. Measurement of the ABPI is important in order to exclude arterial disease as the cause of ulceration or as a possible risk factor that might inhibit treatment. An ABPI of >0.80 leads to diagnosis of a venous leg ulcer, whereas patients with the ABPI of <0.92 indicates the presence of arterial disease.11 An
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index of about 0.8 or below is generally considered indicative of significant arterial disease. These patients should be excluded from high-compression bandage therapy since its use could lead to further ulcer complications or even limb amputation.12 The Doppler ultrasonic measurement technique produces elevated readings when diagnosing patients that may have diabetes and other conditions with calcified arteries.13 Ultrasound scanning Colour duplex ultrasound scanning is currently the technique of choice in order to assess the venous system of the lower limb. The technique combines ultrasound imaging with pulsated Doppler ultrasound and provides detailed anatomic information of the superficial, deep, and perforating venous systems. It can identify specific veins in which blood reflux occurs or obstructions which may be contributing to venous hypertension. Photoplethysmography and air plethysmography Photoplethysmography and air plethysmography are simple tests designed to evaluate calf muscle dysfunction and degree of venous reflux. The techniques are used to observe the change in blood volume within the lower limb before and after exercise. Application of a tourniquet to restrict blood flow within the superficial system allows the deep venous system to be assessed for a potential obstruction. Invasive venous tests such as ascending and descending phlebography are also used to assess venous insufficiency. Phlebography combines electromagnetic radiation (X-rays) and fluorescent materials to provide a technique that allows the veins to be clearly visualised. These immunofluorescence methods can detect venous outflow obstructions, provide information of valvular incompetence, and also highlight the presence of pericapillary fibrin.14 Phlebography is usually used before a patient undergoes valvular surgery.
6.4
Venous leg ulcer treatment
It should be stated that venous leg ulcers are chronic and there is no medication to cure the disease other than the compression therapy. A sustained graduated compression mainly enhances the flow of blood back to the heart, improves the functioning of valves and calf muscle pumps, reduces oedema and prevents the swelling of veins. Mostly elderly people are prone to develop DVT, varicose veins and venous leg ulcers. Venous leg ulcers are the most frequently occurring type of chronic wound accounting for 80 to 90% of all lower extremity ulceration and compression remains the
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mainstay of treatment.15 Compression treatment has been extensively covered in a Cochrane review.16
6.4.1 Compression bandages Compression bandaging is the ‘Gold standard’ for managing venous leg ulceration and treating the underlying venous insufficiency.17 The main function of a compression bandage is to exert external pressure onto the leg, and this is determined by its elastic properties. A recent study investigated the degree of pressure required to narrow and occlude the superficial and deep veins of the calf when a subject is in different body positions. For compression therapy to be effective, it has to exceed the hydrostatic pressure within the veins in order to narrow the vessels and achieve a subsequent increase in blood flow. Initial narrowing of the veins occurred at a pressure of 30–40 mm Hg in both the sitting and standing positions and complete occlusion occurred at 20–25 mm Hg (supine position), 50–60 mm Hg (sitting position), and at 70 mm Hg (standing position).18 In a further study, Partsch19 compared the different haemodynamic effects that are achieved when using compression stockings and compression bandages. The study concluded that compression stockings which exert external pressures of up to 40 mm Hg are effective in increasing blood flow velocity (supine position), and reducing oedema after extended periods of sitting and standing. In addition, short-stretch and multi-layered compression bandages which exert pressures of over 40 mm Hg reduce venous hypertension during walking and improve the venous pumping function. Classification Compression bandages are mainly classified as elastic and non-elastic. Elastic compression bandages (Table 6.2) are categorised according to the level of pressure generated on the angle of an average leg. Class 3a bandages provide light compression of 14–17 mm Hg, moderate compression (18–24 mm Hg) is imparted by class 3b bandages, and 3c type bandages impart high compression between 25 and 35 mm Hg. 20 The 3d type extrahigh-compression bandages (up to 60 mm Hg) are not often used because the very high pressure generated will reduce the blood supply to the skin. It must be stated that approximately 30–40 mm Hg at the ankle which reduces to 15–20 mm Hg at the calf is generally adequate for healing most types of venous leg ulcers. 21 Compression stockings provide support to treat DVT and varicose veins, and to prevent venous leg ulcers. They are classified as light support (Class 1), medium support (Class 2) and strong support (Class 3). 22
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Table 6.2 Elastic Bandage Classification Class
Bandage type
Bandage function
1
Lightweight conforming
2
Light support
3a
Light compression
3b
Moderate compression
3c
High compression
3d
Extra high compression
Apply very low levels of sub-bandage pressure and are used to hold dressings in place Apply moderate sub-bandage pressure and are used to prevent oedema or for the treatment of mixed aetiology ulcers Exert a pressure range of 14–17 mm Hg at the ankle Exert a pressure range of 18–24 mm Hg at the ankle Exert a pressure range of 25–35 mm Hg at the ankle Exert a pressure of up to 60 mm Hg at the ankle
Compression hosiery Elastic stockings are used for the treatment of DVT which is associated with a risk of pulmonary embolism and post thrombotic syndrome (PTS). 23 The recent introduction of two-layered high-compression hosiery kits may have provided an alternative solution for the treatment of venous ulceration since they are easier and safer to apply than traditional compression bandages and improve patient concordance. 24 The hosiery kits consist of two knee-high garments; a light compression (10 mm Hg) understocking and a Class 3 compression-hosiery overstocking providing 25–35 mm Hg. The understocking is applied on to the leg fi rst and owing to its smooth surface allows the overstocking to slip over it for ease of application. Compression stockings (antiembolism stockings) are the most commonly available and accepted methods for DVT treatment. Compression hosiery contains elastomeric yarns that are capable of recovering their size and shape after extension giving similar performance properties to long-stretch compression bandages. There are three classification Standards for graduated compression hosiery: the British Standard, 25 French Standard, 26 and German Standard. 27 Attempts were made to produce a European Standard (draft ENV 12718:2001) but consensus could not be achieved and consequently the Standard was cancelled. 28 The above Standards generally classify compression hosiery according to the level of pressure exerted around the ankle (Table 6.3). 25–27 Patients are advised to wear elastic stockings every day after the ulcer has healed in order to prevent recurrence. 29 However, in everyday practice
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Table 6.3 European Classification of Compression Hosiery Class
Support
British Standard BS 6612:1985
French Standard ASQUAL
German Standard RAL-GZ 387:2000
1 2 3 4
Light Medium Strong Heavy
14–17 mm Hg 18–24 mm Hg 25–35 mm Hg Not reported
10–15 mm Hg 15–20 mm Hg 20–36 mm Hg >36 mm Hg
18–21 mm Hg 23–32 mm Hg 34–46 mm Hg >49 mm Hg
patients are reluctant to wear compression hosiery on a long-term basis. 30 A systematic review concluded that there is circumstantial evidence to suggest that compression hosiery does reduce ulcer recurrence but there is no strong evidence to support this. In addition, high-compression stockings may be more effective than moderate compression in preventing ulcer recurrence. 31 Compression system Compression can be exerted to the leg either by a single-layer bandage or multilayer bandages. In the UK, a four-layer bandaging system is widely used whilst in Europe and Australia the non-elastic two-layer short stretch bandage regime is the standard treatment. A typical four-layer compression bandage system comprises of padding bandage, crepe bandage, highcompression bandage and cohesive bandage. Both the two layer and four layer systems require padding bandage (wadding or orthopaedic wool) that is applied next to the skin and underneath the short stretch or compression bandages. A plaster type non-elastic bandage, Unna’s boot is favoured in the USA. However, compression would be achieved by three-layer dressing that consists of Unna’s boot, continuous gauze dressing, followed by an outer layer of elastic wrap. It should be realised that Unna’s boot, being rigid, is uncomfortable to wear and medical professionals are unable to monitor the ulcer after the boot is applied. Unna’s Boot provides a high working pressure when the calf muscle contracts, but very little pressure while the patient is at rest. 32 The high working pressure serves to increase blood flow, while the low resting pressure facilitates deep venous fi lling. The Unna’s Boot is only effective in ambulatory patients and requires constant re-application as leg volume decreases owing to a reduction in oedema. Used widely in the USA, the Unna’s Boot system is uncomfortable to wear because of its rigidity and is both expensive and difficult to apply.
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A multi-centre study compared the venous ulcer healing rates between Unna’s Boot and CircAid® in 38 patients. 33 The time to heal for the Unna’s Boot group of patients was 9.69 ± 3.28 weeks in comparison to the CircAid® device group which was 7.98 ± 4.41 weeks. The study data supported a trend towards more rapid ulcer healing in the CircAid® device group but the results did not reach statistical significance owing to the small number of patients studied. Short-stretch bandages function in a similar manner to the rigid/inelastic Unna’s Boot. They consist of 100% high twisted cotton yarns and are applied onto the limb at full extension. Unlike elastic bandages, short-stretch bandages firmly hold the calf thereby providing a high working pressure when the patient walks. 34
6.4.2 Padding bandages (orthopaedic wool or wadding) Padding bandages play a significant role in the successful treatment of venous leg ulcers. A variety of padding bandages are used beneath the compression bandage system as padding layers in order to evenly distribute pressure and give protection. They absorb high pressure created at the tibia and fibula regions. It will be noticed that the structure of a padding bandage is regarded as an important factor in producing a uniform pressure distribution. Research has shown that the majority of the commercially available bandages do not provide uniform pressure distribution. 35,36 A padding at least 2.5 cm thick is placed between the limb and the compression bandage to distribute the pressure evenly at the ankle as well as the calf region. Wadding helps to protect the vulnerable areas of the leg from the high compression levels required along the rest of the leg. 37 Padding can also be used to reshape legs which are not narrower at the ankle than the calf. It makes the limb more like a cone-shape so that the pressure is distributed over a pressure gradient with more pressure at the foot and less at the leg. Generally, the longer a compression bandage system is to remain in place, the greater is the amount of padding needed. An ideal padding bandage should be: • lightweight and easy to handle; • soft and impart cushioning effect to the limb; • capable of preventing tissue damage; • capable of distributing pressure evenly around the leg; • a good absorbent and have good wicking properties; • comfortable and should not produce irritation or any allergic reaction to the skin on prolonged contact; • easily tearable by hand; and • cheap.
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6.4.3 Ideal compression bandages It should be noted that compression bandages may be harmful if not applied properly. They provide high tension as well as high pressure. A thorough assessment involving several criteria is therefore essential before applying a compression bandage on a limb. For example, it is important to consider the magnitude of the pressure, the distribution of the pressure, the duration of the pressure, the radius of the limb and the number of bandage layers. The ability of a bandage to provide compression is determined by its construction and the tensile force generated in the elastomeric fibres when extended. Compression can be calculated by Laplace’s Law, which states that the sub-bandage pressure is directly proportional to the bandage tension during application and the number of layers applied but inversely proportional to limb radius. 38 Sub-bandage pressure is a function of the tension induced into the compression bandage during application. Applying the bandage with a 50% overlap effectively produces two layers, which generates twice the pressure. When a compression bandage is applied at a constant tension on a limb of increasing circumference, it will produce a sub-bandage pressure gradient with the highest pressure exerted on the ankle. The sub-bandage pressure will increase for people with smaller ankles. The ability of a bandage to maintain sub-bandage pressure is determined by the elastomeric properties of the yarns, the fabric structure, as well as the fi nishing treatments applied to the fabric. The structure of a compression bandage is regarded as an important factor in producing a uniform pressure distribution. An ideal compression bandage should: • provide compression appropriate for the individual; • provide pressure evenly distributed over the anatomical contours; • provide a gradient pressure diminishing from the angle to the upper calf; • maintain pressure and remain in position until the next change of dressing; • extend from the base of the toes to the tibial tuberosity without gap; • function in a complimentary way with the dressing; and • possess non-irritant and non-allergenic properties.
6.4.4 Ideal bandage pressure Compression bandages are mostly used during the initial therapy phase where the aim of treatment is to reduce oedema and overcome venous insufficiency. A number of different types of compression bandage systems are commercially available and, as discussed, the bandages are classified as either rigid/inelastic, short-stretch, long-stretch, or multilayered. The type of fabric construction influences the degree of extensibility that the bandage
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will have. At some point, the bandage will not be able to extend or stretch any further (lock-out) under a predetermined tension. Evidence suggests that a sub-bandage pressure of 35–40 mm Hg at the ankle, which gradually reduces to 17–20 mm Hg at the knee, is required to overcome venous hypertension and successfully treat venous leg ulcers. 39 A recent study investigated the degree of pressure that is required to narrow and occlude leg veins when a subject is in different body positions. The authors found that initial narrowing of the veins occurred at a pressure of 30–40 mm Hg in both the sitting and standing positions. Complete occlusion of the superficial and deep leg veins occurred at 20–25 mm Hg (supine position), 50–60 mm Hg (sitting position), and at 70 mm Hg (standing position).18
6.5
Applications of bandages
The elastic properties of the bandages help to provide a high recoiling force, which serves to increase venous flow and reduce venous hypertension. In addition, they conform easily around the lower limb and allow for frequent dressing changes. Skill is required to apply compression bandages at the correct tension and to avoid excessive sub-bandage pressures.40 Application of high sub-bandage pressure on patients with any type of micro-vascular disease can lead to further occlusion and pressure necrosis of these vessels.41 Some manufacturers supply compression bandages with a series of geometric markers printed onto the bandage surface. The markers assist in the application of a predetermined level of compression by visually distorting when the bandage is stretched to a specific tension. For example, printed rectangles become squares when the correct bandage tension is reached. In a multilayer bandaging system, three or four layers of different types of bandage are used to provide external compression. A multilayer system may include a combination of nonwoven padding bandage, inelastic creep bandage, elastic compression bandages and cohesive (adhesive) bandage. The different properties of each bandage type contribute to the overall effectiveness of the bandage system. The elastic bandage component provides sustained compression while the cohesive bandage offers rigidity thereby enhancing calf muscle pump function. The four-layer high compression system developed by a clinical group at Charing Cross Hospital (London) has gained wide acceptance for use in UK hospitals. The fourlayer system was developed specifically to incorporate different bandage types and properties in order to overcome the clinical issues of exudate, protection of bony prominences, and the ability to sustain sub-bandage pressure over a period of time.42 In addition, the system was designed to apply the required 40 mm Hg of pressure at the ankle, overcome disproportionate limb size and shape, and to remain in position on the leg without
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slippage. Application of the four-layer system involves fi rst applying a padding bandage layer from the base of the toes to just below the knee. A crepe bandage is applied next followed by an elastic compression bandage. Finally, a cohesive layer is applied in order to add durability and to complete the overall pressure profi le. Examples of different types of compression bandages, cohesive bandages, padding bandages, and multilayer compression systems are shown in Table 6.4. A multilayer high compression bandage system has been shown to provide a safe and effective treatment option for uncomplicated venous leg ulcers. Ulcer healing rates of up to 70% at twelve weeks have been obtained.43 The four-layer bandaging technique has been shown to heal chronic ulcers that have failed to respond with traditional adhesive plaster bandage systems.44 A recent review on compression therapy for venous leg ulcers concluded that a multilayer compression system is more effective than low compression or single-layer compression.45 Table 6.4 Illustration of bandages used in compression therapy Bandage name
Function
Manufacturer
Tensopress Setopress SurePress Adva-co Dauerbinde K Silkolan Tensolan Comprilan Actiban Actico (Cohesive) Rosidal K Co-Plus Tensoplus Coban Surepress Soffban K-soft Softexe Advasoft Flexi-ban Cellona Ultra-soft Ortho-band Formflex Profore Proguide Ultra Four System 4 K-four
Type 3c long stretch bandage Type 3c long stretch bandage Type 3c long stretch bandage Type 3c long stretch bandage Long stretch bandage Type 2 short stretch bandage Type 2 short stretch bandage Type 2 short stretch bandage Type 2 short stretch bandage Type 2 short stretch bandage Type 2 short stretch bandage Cohesive bandage Cohesive bandage Cohesive bandage Padding bandage Padding bandage Padding bandage Padding bandage Padding bandage Padding bandage Padding bandage Padding bandage Padding bandage Padding bandage Multilayer compression system Multilayer compression system Multilayer compression system Multilayer compression system Multilayer compression system
Smith + Nephew Medlock Medical ConvaTec Advancis Medical Lohmann + Rauscher Urgo Limited Smith + Nephew Smith + Nephew Activa Healthcare Activa Healthcare Lohmann + Rauscher Smith + Nephew Smith + Nephew 3M ConvaTec Smith + Nephew Urgo Limited Medlock Medical Advancis Medical Activa Healthcare Lohmann + Rauscher Robinsons Healthcare Millpledge Healthcare Lantor (UK) Limited Smith + Nephew Smith + Nephew Robinsons Healthcare Medlock Medical Urgo Limited
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6.6
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Present problems and novel bandages
During the past few years, there have been increasing concerns relating to the performance of bandages especially pressure distribution properties for the treatment of venous leg ulcers. This is because compression therapy is a complex system and requires two or multilayer bandages, and the performance properties of each layer differ from those of other layers. The widely accepted sustained graduated compression mainly depends on the uniform pressure distribution of different layers of bandages in which textile fibres and bandage structure play a major role. The padding bandages commercially available are nonwovens that are mainly used to distribute the pressure, exerted by the short stretch or compression bandages, evenly around the leg. Otherwise higher pressure at any one point not only damages the venous system but also promotes arterial disease. Therefore, there is a need to distribute the pressure equally and uniformly at all points of the lower limb and this can be achieved by applying an effective padding layer around the leg beneath the compression bandage. In addition, padding bandages should be capable of absorbing the high pressure created at the tibia and fibula regions. Wadding also helps to protect the vulnerable areas of the leg from generating extremely high pressure levels as compared with those required along the rest of the leg. The research carried out at the University of Bolton involving 10 most commonly used commercial padding bandages produced by major medical companies showed that there are significant variations in properties of commercial padding bandages, 35,36 more importantly the commercial bandages do not distribute the pressure evenly at the ankle as well as the calf region (Fig. 6.1). In addition, the integrity of the non-woven bandages is also of great concern. When pres60.00
Measured pressure (mm Hg)
50.00
PB1 PB2 PB3 PB4 PB5 PB6 PB7 PB8 PB9 PB10
40.00
30.00
20.00
10.00
0.00
2.93 5.86 8.79 11.72 14.6517.58 20.5123.4426.3729.22 32.1535.08 38.0140.9443.8746.8049.73 52.6655.6658.5259.99
Applied pressure (mm Hg)
6.1 Pressure distribution of commercial padding bandages.
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sure is applied using compression bandages, the structure of the non-woven bandages may collapse and the bandage would not impart a cushioning effect to the limb. Comfort and a cushioning effect are considered to be essential properties for padding bandages because they stay on the limb for several days. Twelve padding bandages, which consisted of single-component fibres, binary blends and tertiary blends incorporating polyester, bicomponent fibres and natural fibres such as cotton and viscose, have been designed and developed at the University of Bolton (Table 6.5). The salient properties of the developed bandages are: • all the developed padding bandages possess suitable bulkiness; • none of the bandages has lower tensile strength or breaking extension that hinders its performance characteristics as an ideal padding bandage; • the tear resistance of bandages, except 100% hollow viscose (NPB5) is high and this means that the bandage cannot be easily torn by hand after wrapping around the leg. However, making perforations at regular intervals across the bandage facilitates easy tearing; • the absorption of solution containing Na+ and Ca2+ ions (artificial blood) is significantly high, irrespective of fibre type and structure; • the rate of absorption of all the developed bandages is also high; and • the pressure distribution of all the novel bandages is good up to 60 mm Hg (Fig. 6.2). In the UK, multilayer compression systems are recommended for the treatment of venous leg ulcers.46 Although multilayer compression bandages are more effective than single-layer bandages in healing venous leg ulcers,45 it is generally agreed by clinicians that multilayer bandages are too bulky for patients and the cost involved is high. A wide range of compression bandages is available for the treatment of leg ulcers but each of them has a different structure and properties and this influences the variation in performance properties of bandages. In addition, long stretch compression bandages tend to expand when the calf muscle pump is exercised, and the beneficial effect of the calf muscle pump is dissipated. It is a wellestablished practice that elastic compression bandages that extend up to 200% are applied at 50% extension and at 50% overlap to achieve the desired pressure on the limb. It has always been a problem for nurses to exactly stretch the bandages at 50% and apply without losing the stretch from ankle to calf, although there are indicators for the desired stretch (rectangles become squares) in the bandages. Elastic compression bandages are classified into four groups (Table 6.3) according to their ability to produce predetermined levels of compression and it has always been a problem to select the right compression bandage for the treatment. The
Table 6.5 Novel padding bandages Identification code
Product
Fibre type
Fibre dtex; length (mm)
Blend ratio (%)
Structure
NPB1 NPB2 NPB3 NPB4 NPB5 NPB6 NPB7 NPB8 NPB9 NPB10
Single component Single component Single component Single component Single component Single component Binary blends Binary blends Binary blends Binary blends
Polyester Polyester (bleached) Hollow polyester Viscose Hollow viscose Lyocell Polyester/viscose Polyester/viscose Polyester/viscose Polyolefin/viscose
3.3;40 5.3;60 3.3;50 3.3;40 3.3;40 3.3;38 3.3;40/3.3;40 3.3;40/3.3;40 3.3;40/3.3;40 2.2;40/3.3;40
100 100 100 100 100 100 75 : 25 50 : 50 25 : 75 20 : 80
NPB11
Tertiary blends
3.3;40/3.3;40/1.8;22
33 : 33 : 33
NPB12
Tertiary blends
Polyester/viscose/cotton (bleached) Polyester/viscose/polyolefin
Needlepunched (both sides) Needlepunched (both sides) Needlepunched (both sides) Needlepunched (both sides) Needlepunched (both sides) Needlepunched (both sides) Needlepunched (both sides) Needlepunched (both sides) Needlepunched (both sides) Needlepunched (both sides) and thermal bonded Needlepunched (both sides)
3.3;40/3.3;40/2.2;40
60 : 25 : 15
Needlepunched (both sides) and thermal bonded
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Measured pressure (mm Hg)
60.00
50.00
NPB1 NPB2 NPB3
40.00
NPB4 NPB5 NPB6
30.00
NPB7 NPB8 NPB9
20.00
NPB10 NPB11 NPB12
10.00
0.00 2.93 5.86 8.79 11.72 14.6517.58 20.5123.44 26.37 29.2232.1535.08 38.0140.9443.8746.8049.7352.6655.6658.5259.99
Applied pressure (mm Hg)
6.2 Pressure distribution of novel padding bandages.
inelastic short stretch bandage (Type 2) system, which has started to appear in the UK market, has the advantage of applying at full stretch (up to 90% extension) around the limb. Short stretch bandages do not expand when the calf muscle pump is exercised and the force of the muscle is directed back into the leg which promotes venous return. The limitations of short stretch bandages are that a small increase in the volume of the leg will result in a large increase in compression and this means the bandage provides high compression in the upright position and little or no compression in the recumbent position when it is not required. During walking and other exercises the sub-bandage pressure rises steeply and while at rest the pressure comparatively drops. Therefore, patients must be mobile to achieve effective compression and exercise is a vital part of this form of compression. Moreover, the compression bandage is not in contact with the skin when there is a reduction in limb swelling because the short stretch bandage is inelastic, and it has already been stretched to its full. The application of a multilayer bandage system requires expertise and knowledge. Nurses must undergo significant practice-based training in order to develop appropriate bandage application skills needed for multilayer compression system. Successful bandaging relies upon adopting good technique in both stretching the bandage to the correct tension and ensuring proper overlap between layers. In addition, nurses need to have knowledge of the different performance properties of each bandage within the multilayer system, and how the performance each bandage combines is to achieve safe and adequate compression. The ability of multilayer bandage systems to maintain adequate compression levels for up to one week has
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reduced the necessity for frequent dressing changes and has therefore, decreased treatment costs. However, the cost of a multilayer compression system is still relatively high owing to the requirement for a specific bandage for each layer. Tolerance to multilayer compression system is generally good but non-compliance in some patients often results in prolonged or ineffective treatment. Some patients are unable to wear footwear due to the bulkiness of multilayer compression regime. These patients often refuse treatment since the requirement to remain house-bound is totally unacceptable. At night patients fi nd compression bandages too uncomfortable and often remove them in order to sleep. Since the application of multilayer compression systems is complex most patients are unable to re-apply the bandages themselves. In order to address some of the problems mentioned above, a novel nonwoven vari-stretch compression bandages (NVCB) has been designed and developed at the University of Bolton. The principal features of the NVCB are:47,48 • novel non-woven technology was used to develop the variable compression bandages. It should be mentioned that no non-woven compression bandages are listed in Drug Tariff. In the UK, the availability of wound dressings and bandages for use in patients’ homes is dictated by the Drug Tariff; • the performance and properties of the novel bandages are superior to existing multilayer commercial compression bandages. This fulfi ls the requirement of ideal variable pressure from ankle to below knee positions of the limb for the treatment of venous leg ulcers; and • vari-stretch non-woven bandages also meet the standards and the tolerances stipulated by BS 7505.
6.7
Three-dimensional spacer compression bandages
Recently, spacer technology has been increasingly used to produce threedimensional materials for technical textiles sectors such as the automotive, medical, sports and industrial market. The spacer technology is flexible, versatile, cost effective and an ideal route to produce 3D materials for medical use. It is identified that spacer is the right technology to produce novel compression bandages that meet the prerequisites of both ideal padding and compression bandages. The main reasons for the current interest in 3D spacer fabrics for producing novel compression bandages are several-fold. In 3D spacer fabrics, two separate fabric layers are combined with an inner spacer yarn or yarns using either the warp knitting or weft knitting route (Fig. 6.3). The two layers can be produced from different fibre types such as polyester, polyamide, polypropylene, cotton, viscose,
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6.3 A spacer structure.
lyocell and wool and can have completely different structures.49 It is also possible to produce low modulus spacer fabrics by making use of elastic yarns. Elastic compression could be achieved by altering the fabric structure. It should be mentioned that 3D structure allows greater control over elasticity and these structures can be engineered to be uni-directional, bi-directional and multi-directional. Uni-directional elasticity is one of the desired properties for compression bandages. The three-dimensional nature of spacer fabrics makes them ideal for application next to the skin because they have desirable properties that are ideal for the human body. 50 The 3D fabrics are soft, have good resilience that provides a cushioning effect to the body, are breathable, and are able to control heat and moisture transfer.49 For venous leg ulcer applications, such attributes, together with improved elasticity and recovery, promote faster healing. It must be stated that 3D spacer fabrics can also be produced using double-jersey weft knitting machines.49 The main advantages of weft-knitted spacer fabrics over warp-knitted fabrics include cost effectiveness because there is no need to prepare a number of warp beams and spun yarns, and coarser count hairy yarns can be used on weft-knitting machines. Because of the problems associated with the currently available bandages for the treatment of venous leg ulcers as discussed in section 6.6, it is vital to research and develop an alternative bandaging regime that meets all the requirements of an ideal compression system. The research and development programme currently in progress at the University of Bolton has the ultimate aim of developing a single-layer compression-therapy regime for the treatment of venous leg ulcers. The research programme imposes significant challenge in developing 3D spacer
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bandages for compression therapy. There is no doubt that there would be substantial savings for the NHS in the UK and other health services in the world because the ultimate goal of the research programme is to replace the multilayer bandages with a single-layer bandage. A single-layer system simplifies and standardises the application of compression, is more patient friendly, reduces the nursing time, and significantly decreases the treatment cost.
6.7.1
Effect of pressure transference of spacer bandages
Four spacer fabrics identified as black (1), white (2), white (3) and blue (4) were used to study the pressure transference at various pressure ranges. Four padding bandages (PB1a to PB4a) recently available at Drug Tariff were also used for comparison. Pressure transference apparatus and an extension test rig were used to study the pressure transference of spacer bandages both at unrestrained and stretch conditions. It can be observed in Fig. 6.4 that the pressure transference of different spacer bandages at any one point varies, and it mainly depends on the structure and fibre content of the material. It is interesting to note that spacer bandages distributed the applied pressure more uniformly around the leg than did commercial padding bandages (Fig. 6.5). For instance, the white (2) spacer bandage absorbed an applied pressure of 43.9 mm Hg and a pressure of transfer 2 mm Hg at one point. In other words, the absorbed pressure of 41.9 mm Hg is uniformly
Measured pressure (mm Hg)
12.00 10.00 8.00 Black (1) White (2) White (3) Blue (4)
6.00 4.00 2.00 0.00
7.3
14.6
21.9 29.3 36.6 43.9 Applied pressure (mm Hg)
51.2
58.6
6.4 Pressure transference of spacer bandages (relaxed).
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60
Measured pressure (mm Hg)
50
40
30
PB1a PB2a PB3a PB4a
20
10
0
0 2.94 5.9 8.81 11.8 14.7 17.6 20.6 23.5 26.4 29.3 32.2 35.2 38.1 41.1 44 46.9 49.9 52.8 55.7 58.6 60.1
Applied pressure (mm Hg)
6.5 Pressure transference of commercial padding bandages.
distributed inside the fabric structure which is one of the essential requirements for venous leg ulcer treatment. On the other hand, the commercial padding bandage (PB4a) absorbed 43.9 mm Hg and transferred 35 mm Hg at one point (Fig. 6.5) and this means the bandage distributed only 8.9 mm Hg uniformly inside the structure. The higher output pressure from the bandage at one point is undesirable and may slow down and/or block the blood flow in arteries. Figures 6.6 to 6.9 represent the pressure transference of spacer bandages at known pressures under extension up to 120%. It is noticed that an increase in applied pressure does not influence the pressure transference at any one point and the variation is marginal in all the samples. This affi rms that these spacer fabrics can be used as ideal padding bandages and, by controlling the tension, it will be possible to generate the required pressure for the treatment of venous leg ulcers. As discussed in section 6.4.3, the pressure generated on the limb by a bandage is directly proportional to the tension of the bandage and the number of layers but inversely proportional to the width of the bandage and the circumference of the limb. This Laplace’s concept is being applied in the research and development programme into the mathematical modelling of spacer bandages to achieve the required pressure mapping for the treatment of venous leg ulcers at the University of Bolton.
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7.00
Pressure transference (mm Hg)
6.00 5.00 4.00 7.3 (mm Hg) 14.6 (mm Hg) 21.9 (mm Hg) 29.3 (mm Hg) 36.6 (mm Hg) 43.9 (mm Hg) 51.2 (mm Hg) 58.6 (mm Hg)
3.00 2.00 1.00 0.00
0
10
20
30
40
50
60
70
80
90
100
110 120
Fabric extension (%)
6.6 Effect of extension on pressure transference of spacer bandages – black (1).
4.50
Pressure transference (mm Hg)
4.00 3.50 3.00 2.50
7.3 (mm Hg) 14.6 (mm Hg) 21.9 (mm Hg) 29.3 (mm Hg) 36.6 (mm Hg) 43.9 (mm Hg) 51.2 (mm Hg) 58.6 (mm Hg)
2.00 1.50 1.00 0.50 0.00
0
10
20
30
40
50
60
70
80
90
100
Fabric extension (%)
6.7 Effect of extension on pressure transference of spacer bandages – white (2).
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Pressure transference (mm Hg)
6.00 5.00 7.3 (mm Hg) 14.6 (mm Hg) 21.9 (mm Hg) 29.3 (mm Hg) 36.6 (mm Hg) 43.9 (mm Hg) 51.2 (mm Hg) 58.6 (mm Hg)
4.00 3.00 2.00 1.00 0.00
0
10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 Fabric extension (%)
6.8 Effect of extension on pressure transference of spacer bandages – white (3).
10.00
Pressure transference (mm Hg)
9.00 8.00 7.00 6.00 7.3 (mm Hg) 14.6 (mm Hg) 21.9 (mm Hg) 29.3 (mm Hg) 36.6 (mm Hg) 43.9 (mm Hg) 51.2 (mm Hg) 58.6 (mm Hg)
5.00 4.00 3.00 2.00 1.00 0.00
0
10
20
30
40
50
60
70
80
90
Fabric extension (%)
6.9 Effect of extension on pressure transference of spacer bandages – blue (4).
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6.8
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Conclusions
Compression-delivery systems have an important role in the treatment of venous leg ulceration since they can reduce venous reflux, increase venous and arterial blood flow, improve microcirculation, and reduce ankle oedema. There is a variety of compression bandaging systems available, the advantages and disadvantages of each are constantly reviewed and debated. In the UK, for example, a four-layer bandaging system is popular and has been shown to provide a safe and effective treatment option. Other countries, such as the USA, prefer the rigid characteristics of the Unna’s Boot. The success of any compression bandage system relies upon the skill and expertise of the clinician applying it. Moreover, the effective management of venous leg ulcer involves careful selection of bandages to reverse the venous blood flow back to the heart. The contribution of padding as well as compression bandages in healing the ulcer is significant. The advantages and limitations of the existing two-layer and four-layer bandaging regimens have been discussed. It is obvious that the pressure transference of commercial padding bandages varied and none of the padding bandages investigated satisfied the requirements of an ideal padding bandage. On the other hand, the novel padding bandages exhibited a uniform pressure distribution around the leg. The paper also demonstrated the need for developing a single-layer bandaging regime for the benefit of the elderly and to cut the cost of treatment. The use of 3D spacer technology has been investigated and the results affirmed that spacer bandages would be utilised to design and develop a single-layer system that could replace the currently used cumbersome four-layer system. A suitable spacer structure can combine the desirable attributes of both the padding and two-dimensional compression bandages into one composite three-dimensional structure.
6.9
References
1. reichenburg, j., davis, m. Venous Ulcers. Semin Cutan Med Surg 2005; 24(4): 216–226. 2. martson, w.a., carlin, r.e., passman, m.a., farber, m.a., keagy, b.a., parent iii, f.n. Healing rates and cost efficacy of outpatient compression treatment for leg ulcers associated with venous insufficiency. J Vasc Surg 1999; 30(3): 491–498. 3. sarkar, p.k., ballentyne, s. Management of leg ulcers. Postgrad Med J 2000; 76: 674–682. 4. nicholaides, a.n. Investigation of chronic venous insufficiency: a consensus statement (France, March 5–9, 1997). Circulation 2000; 102(20): E126– E163.
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5. margolis, d.j., bilker, w., santanna, j., baumgarten, m. Venous leg ulcer: incidence and prevalence in the elderly. J Am Acad Dermatol 2002; 46(3): 381–386. 6. naschitz, j.e., yeshurun, d., misselevich i., boss j.h. The pathogenesis of lipodermatosclerosis: facts, uncertainties and theories. J Eur Acad Dermatol Venereol 1997; 9(3): 209–214. 7. zimmet, s.e. Venous leg ulcers: modern evaluation and management. Dermatol Surg 1999; 25(3): 236–241. 8. franks, p.j., moffatt, c.j., bosanquet, n., oldroyd, m., greenhalgh, r.m., mccollum, c.n. connolly, m. Community leg ulcer clinics: effect on quality of life. Phlebology 1994; 9(2): 83–86. 9. london, n.j.l., donnelly, r. Ulcerated lower limb. BMJ 2000; 320: 1589–1591. 10. sibbald, r.g. Venous leg ulcers. Ostomy Wound Manage 1998; 44(9): 52–64. 11. sumner, d.s. Non-invasive assessment of peripheral arterial occlusive disease. In: Rutherford, K.S, editor. Vascular Surgery (3rd edition) Philadelphia: WB Saunders, 1998; 41–60. 12. callam, m.j., ruckley, c.v., harper. dale, j.j. Chronic ulceration of the leg: extent of the problem and provision of care. Br Med J (Clin Res Ed) 1985; 290(6485): 1855–1856. 13. mcguckin, m., stineman, m., goin, j., williams, s. Draft guideline: diagnosis and treatment of venous leg ulcers. Ostomy Wound Manage 1996; 42(4): 48–54. 14. valencia, i.c., falabella, a., kirsner, r.s. eaglstein, w.h. Chronic venous insufficiency and venous leg ulceration. J Am Acad Dermatol 2001; 44(3): 401–424. 15. blair, s.d., wright, d.d.i., backhouse, c.m., riddle, e., mccollum, c.n. Sustained compression and the healing of chronic ulcers. BMJ 1988; 297: 1159–1161. 16. cullum, n., nelson, e.a., fletcher, a.w., sheldon, t.a. Compression for venous leg ulcers. Cochrane Database Syst Rev 2004; (2): CD000265. 17. choucair, m., phillips, t.j. Compression therapy. Dermatol Surg 1998; 24(1): 141–148. 18. partsch, b., partsch, h. Calf compression pressure required to achieve venous closure from supine to standing positions. J Vasc Surg 2005; 42(4): 734–738. 19. partsch, h. Do we still need compression bandages? Haemodynamic effects of compression stockings and bandages. Phlebology 2006; 21(3): 132–138. 20. thomas, s. Bandages and bandaging: the science behind the art. Care Sci Pract 1990; 8(2): 56–60. 21. simon, d. Approaches to venous leg ulcer care within the community: compression, pinch skin grafts and simple venous surgery. Ostomy Wound Manage 1996; 42(2): 34–40. 22. anon. The complete Scholl guide to health care for legs. Luton: Scholl, 1996. 23. hach-wunderle, v. düx, m., hoffmann, a., präve, f., zegelman, m., hach, w. Treatment of deep vein thrombosis in the pelvis and leg. Deutsch Ärztebl 2008; 105: 23–34.
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24. polignano, r., guarnera, g., bonadeo, p. Evaluation of SurePress comfort: a new compression system for the management of venous leg ulcers. J Wound Care 2004; 13(9): 387–391. 25. british standards institution. Specification for graduated compression hosiery. BS 6612:1985; London: BSI, 1985. 26. certificat de qualite-produits. Referentiel technique prescrit pourles ortheses elastiques de contention des membres. 1999; Paris: ASQUAL. 27. deutsches institut für gütesicherung und kennzeichnung. Medizinische Kompressionsstrümpfe RAL-GZ 387. 2000; Berlin: Beuth. 28. clark, m., krimmel, g. Lymphoedema and the construction and classification of compression hosiery. Lymphoedema Framework. Template for Practice: compression hosiery in lymphoedema. 2006; London: MEP Ltd. 29. williams, c. Leg ulcer after care: the role of compression hosiery. Br J Nurs 2000; 9(13): 822–828. 30. vowden, k.r., vowder, p. Preventing venous ulcer recurrence: a review. Int Wound J 2006; 3(1): 11–21. 31. nelson, e.a., bell-syer, s.e.m., cullum, n.a. Compression for preventing recurrence of venous ulcers. Cochrane Database System Rev 2000; (4): CD002303. DOI: 10.1002/14651858.CD002303. 32. partsch, h. Compression therapy of the legs: a review. J Dermatol Surg Oncol 1991; 17(10): 799–805. 33. depalma, r.g., kowallek, d., spence, r.k. Comparison of costs and healing rates of two forms of compression in treating venous ulcers. Vasc Surg 1999; 33(6): 683–690. 34. hampton, l. Venous leg ulcers: short stretch bandages for compression therapy. Br J Nurs 1997; 6(17): 990–998. 35. rajendran, s., anand, s.c. Design and development of novel bandages for compression therapy. Br J Nurs (Tissue Viability Supplement) 2003; 12(17): S20–S29. 36. rajendran, s., anand, s.c. Development of novel bandages for compression therapy, Wounds UK 2002, Harrogate, 19–20 November 2002. 37. gibson, b., duncan, v., armstrong, s. Know how: ischaemic leg ulcer. Nurs Times 1997; 93(36): 34–36. 38. moffat, c., harper, p. Leg ulcers. Churchill Livingstone, Edinburgh, 1997. 39. stemmer, r. Ambulatory-elasto-compressive treatment of the lower extremities particularly with elastic stockings. Derm Kassenarzt 1969; 9: 1–8. 40. logan, r.a., thomas, s., harding, e.f., collyer, g. A comparison of sub-bandage pressures produced by experienced and inexperienced bandagers. J Wound Care 1992; 1(3): 23–26. 41. simon, d.a., freak, l., williams, i.m. et al. Progression of arterial disease in patients with healed venous ulcers. J Wound Care 1994; 3(4): 179–180. 42. moffatt, c.j., dickson, d. The Charing Cross high compression four-layer bandaging system. J Wound Care 1993; 2(2): 91–94. 43. nelzen, o., bergqvist, d., lindhagen, a. Leg ulcer etiology – a cross sectional population study. J Vasc Surg 1991; 14(4): 557–564.
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44. buchbinder, d., mccullough, g.m., melick, c.f. Patients evaluated for venous disease may have other pathological considerations contributing to symptomatology. Am J Surg 1993; 166: 211–215. 45. cullum, n., nelson, e.a., fletcher, a.w. sheldon, t.a. Compression for venous leg ulcers. Cochrane Database System Rev 2001; (2): CD000265. DOI:10.1002/ 14651858.CD000265. 46. nhs centre for review and dissemination. University of York. Compression therapy for venous leg ulcers. Effect Healthcare 1997; 3(4): 1–12. 47. rajendran, s., anand, s.c. The contribution of textiles to medical and healthcare products and developing innovative medical devices. Indian J Fibre Text Res 2006; 31: 215–229. 48. rajendran, s., anand, s.c. Challenges in development of woundcare medical devices, FiberMed 06, Tampere, Finland, 7–9 June, 2006. 49. anand, s.c. Spacers – at the technical frontier. Knit Int 2003; 110: 38–41. 50. anon. Spacer fabric focus. Knit Int 2002; 109: 20–22.
Abstract: The application of compression textiles in managing venous leg ulcers is discussed. The classification of compression bandages, merits and limitations of the current compression therapy regimen, and the research into the development of novel orthopaedic padding and compression bandages are highlighted. The role of compression therapy in the treatment of oedema, varicose veins and deep vein thrombosis (DVT) is outlined. Research and development of a novel single-layer 3D spacer bandage, which replaces the existing multilayer bandage regime, is discussed. Key words: wound, venous leg ulcer, padding bandage, compression bandage, 3D spacer bandage.
6.1
Introduction
It has been predicted that there is a substantial market potential for advanced wound dressings. The woundcare industry generated between US$3.5 and 4.5 billion for the period from 2003 to 2006, mostly from the US and Europe. The European advanced wound management market was valued at US$544.4 million in 2004 and is expected to grow by an average of 12.4% a year to US$1.23 billion in 2010. The forecast for annual growth is between 10 and 15% in 2012. An ageing population creates an increased demand for ulcer treatment. The pressure ulcer treatment accounts for 4% of the National Health Service (NHS) annual budget. The annual cost of treating diabetic foot ulceration accounts for 5% of the total NHS budget. The treatment of venous leg ulcers creates considerable demands upon healthcare professionals throughout the world. The total cost to the NHS for venous leg ulcers treatment is about £650 million per annum, which is 1–2% of the total healthcare expenditure. Costs per patient have recently been estimated to be between £1200 and £1400. In the US, venous leg ulcers affect 3.5% of people over the age of 65 and the estimated annual cost is from $1.9 to $2.5 billion. In the EU, the annual cost for treating patients with venous leg ulcers accounts for 1–2% of the overall healthcare expenditure. In Australia, around 1% of the adult population suffer from venous ulceration. 153
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Venous ulcers are the most common type of chronic leg ulceration. Chronic ulcers are defi ned as those lasting six weeks or more.1 In the UK alone, about 1% of the adult population suffers from active ulceration during their life time. 2 Approximately 400 000 patients have the initial symptoms of leg ulcers and 100 000 have open leg ulcers that require treatment. 3 About 80% of patients who have leg ulceration suffer with a venous ulcer. Some patients may have more than one episode of venous ulceration with estimated recurrence rates ranging from 6 to 15%.4 The prevalence of leg ulcers increases with age affecting 1.69% of patients aged between 65 and 95 years. The incidence rate for patients in this age group is estimated at 0.76% for men and 1.42% for women. 5 It has been established that compression therapy, by making use of compression bandages, is an efficient treatment for healing various leg ulcers, despite surgical strategies, electromagnetic therapy and intermittent pneumatic compression.
6.2
Elastic compression bandages
Bandages can be used for many purposes and include retention, support and compression: • Retention bandages are used to retain dressings in the correct position. • Support bandages provide retention and prevent the development of a deformity or change in shape of a mass of tissue due to swelling or sagging. • Compression bandages are employed mainly for the treatment of leg ulcers and varicose veins. Elastomeric compression bandages made with rubber were fi rst used in the late 19th century. However, these have now been replaced by lighter, stronger, more comfortable and washable bandages made from Lycra or other elastane fibres. Modern bandages are either woven or knitted and are designed to provide prescribed levels of compression in accordance with specified performance-based standards (Table 6.1).
Table 6.1 Types of bandages Bandage
Commercial name
Remark
Retention bandage
Slinky®, Stayform ®, K-Band ®, Easifix®, Slinky®, Crinx®, Tensofix® Crepe BP®, Elastocrepe ®
Exerts very little pressure on a limb
Support bandage
Prevents formation of oedema and supports joints
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Table 6.1 Continued Bandage
Commercial name
Compression bandages Light compression (3a)
J-Plus ®, K-Crepe ®
Moderate compression (3b)
Veinopress ®, Granuflex adhesive Compression ® Setopress ®, Tensopress ® Surepress ® Bilastic Forte ®, Blue line webbing ® Zincaband ®, Tarband ®, Quinaband ®, Icthaband ®
High compression (3c) Extra high compression (3d) Paste bandages
Tubular bandages Elasticated Foam padded
6.3
Tubifast®, Tubigrip ® Netelast® Tubipad ®
Remark Exert various pressure, according to the type on a limb Gives sub-bandage pressures of 14– 17 mm Hg at the ankle Sub-bandage pressures 18–24 mm Hg 25–35 mm Hg
Up to 60 mm Hg Woven cotton fabric impregnated with a medicated cream or paste. Used for the treatment of eczema and dermatitis Dressing on awkward sites Provides padding and protection against physical damage
Venous leg ulcers
6.3.1 Venous leg ulcers: problem It is important that the arterial and venous systems should work properly without causing problems to blood circulation around the body. Pure blood flows from the heart to the legs through arteries taking oxygen and food to the muscles, skin and other tissues. Blood then flows back to the heart carrying away waste products through veins. The valves in the veins are unidirectional which means that they allow the venous blood to flow in an upward direction only. If the valves do not work properly or there is not enough pressure in the veins to push back the venous blood towards the heart (chronic venous insufficiency, CVI), the pooling of blood in the veins takes place and this leads to higher pressure on the skin. Because of high pressure and lack of availability of oxygen and food, the skin deteriorates and eventually the ulcer occurs. The high venous pressure causes oedema followed by tissue breakdown. The initial indications of venous leg ulcers
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are oedema, swollen veins (varicose veins), stasis eczema, fibrosis, lipodermatosclerosis, atrophie blanche, ankle flare and blood clots in veins (deep vein thrombosis, DVT). DVT is a growing problem for passengers on longhaul fl ights. DVT blocks blood from flowing towards the heart. Venous ulcers appear in the gaiter area of the lower limb between the ankle and mid-calf. They can vary in size ranging from very small to large ulcers that extend beyond the gaiter area. The wound is characteristically shallow, irregular in shape, and has sloping well-defi ned borders. Typically, the skin surrounding the wound is thickened and hyperpigmented indicating lipodermatosclerosis.6 With chronic ulcers a yellow– white exudate is observed signifying the presence of slough. A shiny appearance indicates a fibrinous base, which inhibits new tissue formation and wound healing. Varicose veins and ankle oedema often accompany a venous ulcer.7 Approximately 80% of patients who have a venous leg ulcer suffer from some form of discomfort, while 20% experience severe or unremitting pain. 8
6.3.2 Diagnosis of venous leg ulcers The diagnosis of lower limb ulceration must start by determining the patient’s full clinical history together with a physical examination of the condition. It is essential to identify possible risk factors that could cause ulceration or impact on the treatment of the ulcer. These risk factors could include arterial disease, trauma and malignancy.9 A number of non-invasive test methods are available to the clinician for investigating the cause of leg ulceration and venous insufficiency. These test methods help to assess the arterial and venous circulation of the patient and can provide information on the location of blood reflux or an obstruction within the veins. Doppler ultrasonography Doppler ultrasonography is used to measure the ankle-to-brachial blood pressure index (ABPI) of the patient. The ultrasound technique produces a signal that identifies the presence of blood flow within the arteries. The ABPI is obtained by measuring the systolic blood pressure within the dorsalis pedis or posterior tibial artery of the lower limb and the ipsilateral brachial artery of the arm.10 The ratio between the ankle systolic pressure and the brachial systolic pressure provides the ABPI value. Measurement of the ABPI is important in order to exclude arterial disease as the cause of ulceration or as a possible risk factor that might inhibit treatment. An ABPI of >0.80 leads to diagnosis of a venous leg ulcer, whereas patients with the ABPI of <0.92 indicates the presence of arterial disease.11 An
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index of about 0.8 or below is generally considered indicative of significant arterial disease. These patients should be excluded from high-compression bandage therapy since its use could lead to further ulcer complications or even limb amputation.12 The Doppler ultrasonic measurement technique produces elevated readings when diagnosing patients that may have diabetes and other conditions with calcified arteries.13 Ultrasound scanning Colour duplex ultrasound scanning is currently the technique of choice in order to assess the venous system of the lower limb. The technique combines ultrasound imaging with pulsated Doppler ultrasound and provides detailed anatomic information of the superficial, deep, and perforating venous systems. It can identify specific veins in which blood reflux occurs or obstructions which may be contributing to venous hypertension. Photoplethysmography and air plethysmography Photoplethysmography and air plethysmography are simple tests designed to evaluate calf muscle dysfunction and degree of venous reflux. The techniques are used to observe the change in blood volume within the lower limb before and after exercise. Application of a tourniquet to restrict blood flow within the superficial system allows the deep venous system to be assessed for a potential obstruction. Invasive venous tests such as ascending and descending phlebography are also used to assess venous insufficiency. Phlebography combines electromagnetic radiation (X-rays) and fluorescent materials to provide a technique that allows the veins to be clearly visualised. These immunofluorescence methods can detect venous outflow obstructions, provide information of valvular incompetence, and also highlight the presence of pericapillary fibrin.14 Phlebography is usually used before a patient undergoes valvular surgery.
6.4
Venous leg ulcer treatment
It should be stated that venous leg ulcers are chronic and there is no medication to cure the disease other than the compression therapy. A sustained graduated compression mainly enhances the flow of blood back to the heart, improves the functioning of valves and calf muscle pumps, reduces oedema and prevents the swelling of veins. Mostly elderly people are prone to develop DVT, varicose veins and venous leg ulcers. Venous leg ulcers are the most frequently occurring type of chronic wound accounting for 80 to 90% of all lower extremity ulceration and compression remains the
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mainstay of treatment.15 Compression treatment has been extensively covered in a Cochrane review.16
6.4.1 Compression bandages Compression bandaging is the ‘Gold standard’ for managing venous leg ulceration and treating the underlying venous insufficiency.17 The main function of a compression bandage is to exert external pressure onto the leg, and this is determined by its elastic properties. A recent study investigated the degree of pressure required to narrow and occlude the superficial and deep veins of the calf when a subject is in different body positions. For compression therapy to be effective, it has to exceed the hydrostatic pressure within the veins in order to narrow the vessels and achieve a subsequent increase in blood flow. Initial narrowing of the veins occurred at a pressure of 30–40 mm Hg in both the sitting and standing positions and complete occlusion occurred at 20–25 mm Hg (supine position), 50–60 mm Hg (sitting position), and at 70 mm Hg (standing position).18 In a further study, Partsch19 compared the different haemodynamic effects that are achieved when using compression stockings and compression bandages. The study concluded that compression stockings which exert external pressures of up to 40 mm Hg are effective in increasing blood flow velocity (supine position), and reducing oedema after extended periods of sitting and standing. In addition, short-stretch and multi-layered compression bandages which exert pressures of over 40 mm Hg reduce venous hypertension during walking and improve the venous pumping function. Classification Compression bandages are mainly classified as elastic and non-elastic. Elastic compression bandages (Table 6.2) are categorised according to the level of pressure generated on the angle of an average leg. Class 3a bandages provide light compression of 14–17 mm Hg, moderate compression (18–24 mm Hg) is imparted by class 3b bandages, and 3c type bandages impart high compression between 25 and 35 mm Hg. 20 The 3d type extrahigh-compression bandages (up to 60 mm Hg) are not often used because the very high pressure generated will reduce the blood supply to the skin. It must be stated that approximately 30–40 mm Hg at the ankle which reduces to 15–20 mm Hg at the calf is generally adequate for healing most types of venous leg ulcers. 21 Compression stockings provide support to treat DVT and varicose veins, and to prevent venous leg ulcers. They are classified as light support (Class 1), medium support (Class 2) and strong support (Class 3). 22
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Table 6.2 Elastic Bandage Classification Class
Bandage type
Bandage function
1
Lightweight conforming
2
Light support
3a
Light compression
3b
Moderate compression
3c
High compression
3d
Extra high compression
Apply very low levels of sub-bandage pressure and are used to hold dressings in place Apply moderate sub-bandage pressure and are used to prevent oedema or for the treatment of mixed aetiology ulcers Exert a pressure range of 14–17 mm Hg at the ankle Exert a pressure range of 18–24 mm Hg at the ankle Exert a pressure range of 25–35 mm Hg at the ankle Exert a pressure of up to 60 mm Hg at the ankle
Compression hosiery Elastic stockings are used for the treatment of DVT which is associated with a risk of pulmonary embolism and post thrombotic syndrome (PTS). 23 The recent introduction of two-layered high-compression hosiery kits may have provided an alternative solution for the treatment of venous ulceration since they are easier and safer to apply than traditional compression bandages and improve patient concordance. 24 The hosiery kits consist of two knee-high garments; a light compression (10 mm Hg) understocking and a Class 3 compression-hosiery overstocking providing 25–35 mm Hg. The understocking is applied on to the leg fi rst and owing to its smooth surface allows the overstocking to slip over it for ease of application. Compression stockings (antiembolism stockings) are the most commonly available and accepted methods for DVT treatment. Compression hosiery contains elastomeric yarns that are capable of recovering their size and shape after extension giving similar performance properties to long-stretch compression bandages. There are three classification Standards for graduated compression hosiery: the British Standard, 25 French Standard, 26 and German Standard. 27 Attempts were made to produce a European Standard (draft ENV 12718:2001) but consensus could not be achieved and consequently the Standard was cancelled. 28 The above Standards generally classify compression hosiery according to the level of pressure exerted around the ankle (Table 6.3). 25–27 Patients are advised to wear elastic stockings every day after the ulcer has healed in order to prevent recurrence. 29 However, in everyday practice
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Table 6.3 European Classification of Compression Hosiery Class
Support
British Standard BS 6612:1985
French Standard ASQUAL
German Standard RAL-GZ 387:2000
1 2 3 4
Light Medium Strong Heavy
14–17 mm Hg 18–24 mm Hg 25–35 mm Hg Not reported
10–15 mm Hg 15–20 mm Hg 20–36 mm Hg >36 mm Hg
18–21 mm Hg 23–32 mm Hg 34–46 mm Hg >49 mm Hg
patients are reluctant to wear compression hosiery on a long-term basis. 30 A systematic review concluded that there is circumstantial evidence to suggest that compression hosiery does reduce ulcer recurrence but there is no strong evidence to support this. In addition, high-compression stockings may be more effective than moderate compression in preventing ulcer recurrence. 31 Compression system Compression can be exerted to the leg either by a single-layer bandage or multilayer bandages. In the UK, a four-layer bandaging system is widely used whilst in Europe and Australia the non-elastic two-layer short stretch bandage regime is the standard treatment. A typical four-layer compression bandage system comprises of padding bandage, crepe bandage, highcompression bandage and cohesive bandage. Both the two layer and four layer systems require padding bandage (wadding or orthopaedic wool) that is applied next to the skin and underneath the short stretch or compression bandages. A plaster type non-elastic bandage, Unna’s boot is favoured in the USA. However, compression would be achieved by three-layer dressing that consists of Unna’s boot, continuous gauze dressing, followed by an outer layer of elastic wrap. It should be realised that Unna’s boot, being rigid, is uncomfortable to wear and medical professionals are unable to monitor the ulcer after the boot is applied. Unna’s Boot provides a high working pressure when the calf muscle contracts, but very little pressure while the patient is at rest. 32 The high working pressure serves to increase blood flow, while the low resting pressure facilitates deep venous fi lling. The Unna’s Boot is only effective in ambulatory patients and requires constant re-application as leg volume decreases owing to a reduction in oedema. Used widely in the USA, the Unna’s Boot system is uncomfortable to wear because of its rigidity and is both expensive and difficult to apply.
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A multi-centre study compared the venous ulcer healing rates between Unna’s Boot and CircAid® in 38 patients. 33 The time to heal for the Unna’s Boot group of patients was 9.69 ± 3.28 weeks in comparison to the CircAid® device group which was 7.98 ± 4.41 weeks. The study data supported a trend towards more rapid ulcer healing in the CircAid® device group but the results did not reach statistical significance owing to the small number of patients studied. Short-stretch bandages function in a similar manner to the rigid/inelastic Unna’s Boot. They consist of 100% high twisted cotton yarns and are applied onto the limb at full extension. Unlike elastic bandages, short-stretch bandages firmly hold the calf thereby providing a high working pressure when the patient walks. 34
6.4.2 Padding bandages (orthopaedic wool or wadding) Padding bandages play a significant role in the successful treatment of venous leg ulcers. A variety of padding bandages are used beneath the compression bandage system as padding layers in order to evenly distribute pressure and give protection. They absorb high pressure created at the tibia and fibula regions. It will be noticed that the structure of a padding bandage is regarded as an important factor in producing a uniform pressure distribution. Research has shown that the majority of the commercially available bandages do not provide uniform pressure distribution. 35,36 A padding at least 2.5 cm thick is placed between the limb and the compression bandage to distribute the pressure evenly at the ankle as well as the calf region. Wadding helps to protect the vulnerable areas of the leg from the high compression levels required along the rest of the leg. 37 Padding can also be used to reshape legs which are not narrower at the ankle than the calf. It makes the limb more like a cone-shape so that the pressure is distributed over a pressure gradient with more pressure at the foot and less at the leg. Generally, the longer a compression bandage system is to remain in place, the greater is the amount of padding needed. An ideal padding bandage should be: • lightweight and easy to handle; • soft and impart cushioning effect to the limb; • capable of preventing tissue damage; • capable of distributing pressure evenly around the leg; • a good absorbent and have good wicking properties; • comfortable and should not produce irritation or any allergic reaction to the skin on prolonged contact; • easily tearable by hand; and • cheap.
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6.4.3 Ideal compression bandages It should be noted that compression bandages may be harmful if not applied properly. They provide high tension as well as high pressure. A thorough assessment involving several criteria is therefore essential before applying a compression bandage on a limb. For example, it is important to consider the magnitude of the pressure, the distribution of the pressure, the duration of the pressure, the radius of the limb and the number of bandage layers. The ability of a bandage to provide compression is determined by its construction and the tensile force generated in the elastomeric fibres when extended. Compression can be calculated by Laplace’s Law, which states that the sub-bandage pressure is directly proportional to the bandage tension during application and the number of layers applied but inversely proportional to limb radius. 38 Sub-bandage pressure is a function of the tension induced into the compression bandage during application. Applying the bandage with a 50% overlap effectively produces two layers, which generates twice the pressure. When a compression bandage is applied at a constant tension on a limb of increasing circumference, it will produce a sub-bandage pressure gradient with the highest pressure exerted on the ankle. The sub-bandage pressure will increase for people with smaller ankles. The ability of a bandage to maintain sub-bandage pressure is determined by the elastomeric properties of the yarns, the fabric structure, as well as the fi nishing treatments applied to the fabric. The structure of a compression bandage is regarded as an important factor in producing a uniform pressure distribution. An ideal compression bandage should: • provide compression appropriate for the individual; • provide pressure evenly distributed over the anatomical contours; • provide a gradient pressure diminishing from the angle to the upper calf; • maintain pressure and remain in position until the next change of dressing; • extend from the base of the toes to the tibial tuberosity without gap; • function in a complimentary way with the dressing; and • possess non-irritant and non-allergenic properties.
6.4.4 Ideal bandage pressure Compression bandages are mostly used during the initial therapy phase where the aim of treatment is to reduce oedema and overcome venous insufficiency. A number of different types of compression bandage systems are commercially available and, as discussed, the bandages are classified as either rigid/inelastic, short-stretch, long-stretch, or multilayered. The type of fabric construction influences the degree of extensibility that the bandage
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will have. At some point, the bandage will not be able to extend or stretch any further (lock-out) under a predetermined tension. Evidence suggests that a sub-bandage pressure of 35–40 mm Hg at the ankle, which gradually reduces to 17–20 mm Hg at the knee, is required to overcome venous hypertension and successfully treat venous leg ulcers. 39 A recent study investigated the degree of pressure that is required to narrow and occlude leg veins when a subject is in different body positions. The authors found that initial narrowing of the veins occurred at a pressure of 30–40 mm Hg in both the sitting and standing positions. Complete occlusion of the superficial and deep leg veins occurred at 20–25 mm Hg (supine position), 50–60 mm Hg (sitting position), and at 70 mm Hg (standing position).18
6.5
Applications of bandages
The elastic properties of the bandages help to provide a high recoiling force, which serves to increase venous flow and reduce venous hypertension. In addition, they conform easily around the lower limb and allow for frequent dressing changes. Skill is required to apply compression bandages at the correct tension and to avoid excessive sub-bandage pressures.40 Application of high sub-bandage pressure on patients with any type of micro-vascular disease can lead to further occlusion and pressure necrosis of these vessels.41 Some manufacturers supply compression bandages with a series of geometric markers printed onto the bandage surface. The markers assist in the application of a predetermined level of compression by visually distorting when the bandage is stretched to a specific tension. For example, printed rectangles become squares when the correct bandage tension is reached. In a multilayer bandaging system, three or four layers of different types of bandage are used to provide external compression. A multilayer system may include a combination of nonwoven padding bandage, inelastic creep bandage, elastic compression bandages and cohesive (adhesive) bandage. The different properties of each bandage type contribute to the overall effectiveness of the bandage system. The elastic bandage component provides sustained compression while the cohesive bandage offers rigidity thereby enhancing calf muscle pump function. The four-layer high compression system developed by a clinical group at Charing Cross Hospital (London) has gained wide acceptance for use in UK hospitals. The fourlayer system was developed specifically to incorporate different bandage types and properties in order to overcome the clinical issues of exudate, protection of bony prominences, and the ability to sustain sub-bandage pressure over a period of time.42 In addition, the system was designed to apply the required 40 mm Hg of pressure at the ankle, overcome disproportionate limb size and shape, and to remain in position on the leg without
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slippage. Application of the four-layer system involves fi rst applying a padding bandage layer from the base of the toes to just below the knee. A crepe bandage is applied next followed by an elastic compression bandage. Finally, a cohesive layer is applied in order to add durability and to complete the overall pressure profi le. Examples of different types of compression bandages, cohesive bandages, padding bandages, and multilayer compression systems are shown in Table 6.4. A multilayer high compression bandage system has been shown to provide a safe and effective treatment option for uncomplicated venous leg ulcers. Ulcer healing rates of up to 70% at twelve weeks have been obtained.43 The four-layer bandaging technique has been shown to heal chronic ulcers that have failed to respond with traditional adhesive plaster bandage systems.44 A recent review on compression therapy for venous leg ulcers concluded that a multilayer compression system is more effective than low compression or single-layer compression.45 Table 6.4 Illustration of bandages used in compression therapy Bandage name
Function
Manufacturer
Tensopress Setopress SurePress Adva-co Dauerbinde K Silkolan Tensolan Comprilan Actiban Actico (Cohesive) Rosidal K Co-Plus Tensoplus Coban Surepress Soffban K-soft Softexe Advasoft Flexi-ban Cellona Ultra-soft Ortho-band Formflex Profore Proguide Ultra Four System 4 K-four
Type 3c long stretch bandage Type 3c long stretch bandage Type 3c long stretch bandage Type 3c long stretch bandage Long stretch bandage Type 2 short stretch bandage Type 2 short stretch bandage Type 2 short stretch bandage Type 2 short stretch bandage Type 2 short stretch bandage Type 2 short stretch bandage Cohesive bandage Cohesive bandage Cohesive bandage Padding bandage Padding bandage Padding bandage Padding bandage Padding bandage Padding bandage Padding bandage Padding bandage Padding bandage Padding bandage Multilayer compression system Multilayer compression system Multilayer compression system Multilayer compression system Multilayer compression system
Smith + Nephew Medlock Medical ConvaTec Advancis Medical Lohmann + Rauscher Urgo Limited Smith + Nephew Smith + Nephew Activa Healthcare Activa Healthcare Lohmann + Rauscher Smith + Nephew Smith + Nephew 3M ConvaTec Smith + Nephew Urgo Limited Medlock Medical Advancis Medical Activa Healthcare Lohmann + Rauscher Robinsons Healthcare Millpledge Healthcare Lantor (UK) Limited Smith + Nephew Smith + Nephew Robinsons Healthcare Medlock Medical Urgo Limited
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6.6
165
Present problems and novel bandages
During the past few years, there have been increasing concerns relating to the performance of bandages especially pressure distribution properties for the treatment of venous leg ulcers. This is because compression therapy is a complex system and requires two or multilayer bandages, and the performance properties of each layer differ from those of other layers. The widely accepted sustained graduated compression mainly depends on the uniform pressure distribution of different layers of bandages in which textile fibres and bandage structure play a major role. The padding bandages commercially available are nonwovens that are mainly used to distribute the pressure, exerted by the short stretch or compression bandages, evenly around the leg. Otherwise higher pressure at any one point not only damages the venous system but also promotes arterial disease. Therefore, there is a need to distribute the pressure equally and uniformly at all points of the lower limb and this can be achieved by applying an effective padding layer around the leg beneath the compression bandage. In addition, padding bandages should be capable of absorbing the high pressure created at the tibia and fibula regions. Wadding also helps to protect the vulnerable areas of the leg from generating extremely high pressure levels as compared with those required along the rest of the leg. The research carried out at the University of Bolton involving 10 most commonly used commercial padding bandages produced by major medical companies showed that there are significant variations in properties of commercial padding bandages, 35,36 more importantly the commercial bandages do not distribute the pressure evenly at the ankle as well as the calf region (Fig. 6.1). In addition, the integrity of the non-woven bandages is also of great concern. When pres60.00
Measured pressure (mm Hg)
50.00
PB1 PB2 PB3 PB4 PB5 PB6 PB7 PB8 PB9 PB10
40.00
30.00
20.00
10.00
0.00
2.93 5.86 8.79 11.72 14.6517.58 20.5123.4426.3729.22 32.1535.08 38.0140.9443.8746.8049.73 52.6655.6658.5259.99
Applied pressure (mm Hg)
6.1 Pressure distribution of commercial padding bandages.
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sure is applied using compression bandages, the structure of the non-woven bandages may collapse and the bandage would not impart a cushioning effect to the limb. Comfort and a cushioning effect are considered to be essential properties for padding bandages because they stay on the limb for several days. Twelve padding bandages, which consisted of single-component fibres, binary blends and tertiary blends incorporating polyester, bicomponent fibres and natural fibres such as cotton and viscose, have been designed and developed at the University of Bolton (Table 6.5). The salient properties of the developed bandages are: • all the developed padding bandages possess suitable bulkiness; • none of the bandages has lower tensile strength or breaking extension that hinders its performance characteristics as an ideal padding bandage; • the tear resistance of bandages, except 100% hollow viscose (NPB5) is high and this means that the bandage cannot be easily torn by hand after wrapping around the leg. However, making perforations at regular intervals across the bandage facilitates easy tearing; • the absorption of solution containing Na+ and Ca2+ ions (artificial blood) is significantly high, irrespective of fibre type and structure; • the rate of absorption of all the developed bandages is also high; and • the pressure distribution of all the novel bandages is good up to 60 mm Hg (Fig. 6.2). In the UK, multilayer compression systems are recommended for the treatment of venous leg ulcers.46 Although multilayer compression bandages are more effective than single-layer bandages in healing venous leg ulcers,45 it is generally agreed by clinicians that multilayer bandages are too bulky for patients and the cost involved is high. A wide range of compression bandages is available for the treatment of leg ulcers but each of them has a different structure and properties and this influences the variation in performance properties of bandages. In addition, long stretch compression bandages tend to expand when the calf muscle pump is exercised, and the beneficial effect of the calf muscle pump is dissipated. It is a wellestablished practice that elastic compression bandages that extend up to 200% are applied at 50% extension and at 50% overlap to achieve the desired pressure on the limb. It has always been a problem for nurses to exactly stretch the bandages at 50% and apply without losing the stretch from ankle to calf, although there are indicators for the desired stretch (rectangles become squares) in the bandages. Elastic compression bandages are classified into four groups (Table 6.3) according to their ability to produce predetermined levels of compression and it has always been a problem to select the right compression bandage for the treatment. The
Table 6.5 Novel padding bandages Identification code
Product
Fibre type
Fibre dtex; length (mm)
Blend ratio (%)
Structure
NPB1 NPB2 NPB3 NPB4 NPB5 NPB6 NPB7 NPB8 NPB9 NPB10
Single component Single component Single component Single component Single component Single component Binary blends Binary blends Binary blends Binary blends
Polyester Polyester (bleached) Hollow polyester Viscose Hollow viscose Lyocell Polyester/viscose Polyester/viscose Polyester/viscose Polyolefin/viscose
3.3;40 5.3;60 3.3;50 3.3;40 3.3;40 3.3;38 3.3;40/3.3;40 3.3;40/3.3;40 3.3;40/3.3;40 2.2;40/3.3;40
100 100 100 100 100 100 75 : 25 50 : 50 25 : 75 20 : 80
NPB11
Tertiary blends
3.3;40/3.3;40/1.8;22
33 : 33 : 33
NPB12
Tertiary blends
Polyester/viscose/cotton (bleached) Polyester/viscose/polyolefin
Needlepunched (both sides) Needlepunched (both sides) Needlepunched (both sides) Needlepunched (both sides) Needlepunched (both sides) Needlepunched (both sides) Needlepunched (both sides) Needlepunched (both sides) Needlepunched (both sides) Needlepunched (both sides) and thermal bonded Needlepunched (both sides)
3.3;40/3.3;40/2.2;40
60 : 25 : 15
Needlepunched (both sides) and thermal bonded
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Measured pressure (mm Hg)
60.00
50.00
NPB1 NPB2 NPB3
40.00
NPB4 NPB5 NPB6
30.00
NPB7 NPB8 NPB9
20.00
NPB10 NPB11 NPB12
10.00
0.00 2.93 5.86 8.79 11.72 14.6517.58 20.5123.44 26.37 29.2232.1535.08 38.0140.9443.8746.8049.7352.6655.6658.5259.99
Applied pressure (mm Hg)
6.2 Pressure distribution of novel padding bandages.
inelastic short stretch bandage (Type 2) system, which has started to appear in the UK market, has the advantage of applying at full stretch (up to 90% extension) around the limb. Short stretch bandages do not expand when the calf muscle pump is exercised and the force of the muscle is directed back into the leg which promotes venous return. The limitations of short stretch bandages are that a small increase in the volume of the leg will result in a large increase in compression and this means the bandage provides high compression in the upright position and little or no compression in the recumbent position when it is not required. During walking and other exercises the sub-bandage pressure rises steeply and while at rest the pressure comparatively drops. Therefore, patients must be mobile to achieve effective compression and exercise is a vital part of this form of compression. Moreover, the compression bandage is not in contact with the skin when there is a reduction in limb swelling because the short stretch bandage is inelastic, and it has already been stretched to its full. The application of a multilayer bandage system requires expertise and knowledge. Nurses must undergo significant practice-based training in order to develop appropriate bandage application skills needed for multilayer compression system. Successful bandaging relies upon adopting good technique in both stretching the bandage to the correct tension and ensuring proper overlap between layers. In addition, nurses need to have knowledge of the different performance properties of each bandage within the multilayer system, and how the performance each bandage combines is to achieve safe and adequate compression. The ability of multilayer bandage systems to maintain adequate compression levels for up to one week has
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reduced the necessity for frequent dressing changes and has therefore, decreased treatment costs. However, the cost of a multilayer compression system is still relatively high owing to the requirement for a specific bandage for each layer. Tolerance to multilayer compression system is generally good but non-compliance in some patients often results in prolonged or ineffective treatment. Some patients are unable to wear footwear due to the bulkiness of multilayer compression regime. These patients often refuse treatment since the requirement to remain house-bound is totally unacceptable. At night patients fi nd compression bandages too uncomfortable and often remove them in order to sleep. Since the application of multilayer compression systems is complex most patients are unable to re-apply the bandages themselves. In order to address some of the problems mentioned above, a novel nonwoven vari-stretch compression bandages (NVCB) has been designed and developed at the University of Bolton. The principal features of the NVCB are:47,48 • novel non-woven technology was used to develop the variable compression bandages. It should be mentioned that no non-woven compression bandages are listed in Drug Tariff. In the UK, the availability of wound dressings and bandages for use in patients’ homes is dictated by the Drug Tariff; • the performance and properties of the novel bandages are superior to existing multilayer commercial compression bandages. This fulfi ls the requirement of ideal variable pressure from ankle to below knee positions of the limb for the treatment of venous leg ulcers; and • vari-stretch non-woven bandages also meet the standards and the tolerances stipulated by BS 7505.
6.7
Three-dimensional spacer compression bandages
Recently, spacer technology has been increasingly used to produce threedimensional materials for technical textiles sectors such as the automotive, medical, sports and industrial market. The spacer technology is flexible, versatile, cost effective and an ideal route to produce 3D materials for medical use. It is identified that spacer is the right technology to produce novel compression bandages that meet the prerequisites of both ideal padding and compression bandages. The main reasons for the current interest in 3D spacer fabrics for producing novel compression bandages are several-fold. In 3D spacer fabrics, two separate fabric layers are combined with an inner spacer yarn or yarns using either the warp knitting or weft knitting route (Fig. 6.3). The two layers can be produced from different fibre types such as polyester, polyamide, polypropylene, cotton, viscose,
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6.3 A spacer structure.
lyocell and wool and can have completely different structures.49 It is also possible to produce low modulus spacer fabrics by making use of elastic yarns. Elastic compression could be achieved by altering the fabric structure. It should be mentioned that 3D structure allows greater control over elasticity and these structures can be engineered to be uni-directional, bi-directional and multi-directional. Uni-directional elasticity is one of the desired properties for compression bandages. The three-dimensional nature of spacer fabrics makes them ideal for application next to the skin because they have desirable properties that are ideal for the human body. 50 The 3D fabrics are soft, have good resilience that provides a cushioning effect to the body, are breathable, and are able to control heat and moisture transfer.49 For venous leg ulcer applications, such attributes, together with improved elasticity and recovery, promote faster healing. It must be stated that 3D spacer fabrics can also be produced using double-jersey weft knitting machines.49 The main advantages of weft-knitted spacer fabrics over warp-knitted fabrics include cost effectiveness because there is no need to prepare a number of warp beams and spun yarns, and coarser count hairy yarns can be used on weft-knitting machines. Because of the problems associated with the currently available bandages for the treatment of venous leg ulcers as discussed in section 6.6, it is vital to research and develop an alternative bandaging regime that meets all the requirements of an ideal compression system. The research and development programme currently in progress at the University of Bolton has the ultimate aim of developing a single-layer compression-therapy regime for the treatment of venous leg ulcers. The research programme imposes significant challenge in developing 3D spacer
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bandages for compression therapy. There is no doubt that there would be substantial savings for the NHS in the UK and other health services in the world because the ultimate goal of the research programme is to replace the multilayer bandages with a single-layer bandage. A single-layer system simplifies and standardises the application of compression, is more patient friendly, reduces the nursing time, and significantly decreases the treatment cost.
6.7.1
Effect of pressure transference of spacer bandages
Four spacer fabrics identified as black (1), white (2), white (3) and blue (4) were used to study the pressure transference at various pressure ranges. Four padding bandages (PB1a to PB4a) recently available at Drug Tariff were also used for comparison. Pressure transference apparatus and an extension test rig were used to study the pressure transference of spacer bandages both at unrestrained and stretch conditions. It can be observed in Fig. 6.4 that the pressure transference of different spacer bandages at any one point varies, and it mainly depends on the structure and fibre content of the material. It is interesting to note that spacer bandages distributed the applied pressure more uniformly around the leg than did commercial padding bandages (Fig. 6.5). For instance, the white (2) spacer bandage absorbed an applied pressure of 43.9 mm Hg and a pressure of transfer 2 mm Hg at one point. In other words, the absorbed pressure of 41.9 mm Hg is uniformly
Measured pressure (mm Hg)
12.00 10.00 8.00 Black (1) White (2) White (3) Blue (4)
6.00 4.00 2.00 0.00
7.3
14.6
21.9 29.3 36.6 43.9 Applied pressure (mm Hg)
51.2
58.6
6.4 Pressure transference of spacer bandages (relaxed).
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60
Measured pressure (mm Hg)
50
40
30
PB1a PB2a PB3a PB4a
20
10
0
0 2.94 5.9 8.81 11.8 14.7 17.6 20.6 23.5 26.4 29.3 32.2 35.2 38.1 41.1 44 46.9 49.9 52.8 55.7 58.6 60.1
Applied pressure (mm Hg)
6.5 Pressure transference of commercial padding bandages.
distributed inside the fabric structure which is one of the essential requirements for venous leg ulcer treatment. On the other hand, the commercial padding bandage (PB4a) absorbed 43.9 mm Hg and transferred 35 mm Hg at one point (Fig. 6.5) and this means the bandage distributed only 8.9 mm Hg uniformly inside the structure. The higher output pressure from the bandage at one point is undesirable and may slow down and/or block the blood flow in arteries. Figures 6.6 to 6.9 represent the pressure transference of spacer bandages at known pressures under extension up to 120%. It is noticed that an increase in applied pressure does not influence the pressure transference at any one point and the variation is marginal in all the samples. This affi rms that these spacer fabrics can be used as ideal padding bandages and, by controlling the tension, it will be possible to generate the required pressure for the treatment of venous leg ulcers. As discussed in section 6.4.3, the pressure generated on the limb by a bandage is directly proportional to the tension of the bandage and the number of layers but inversely proportional to the width of the bandage and the circumference of the limb. This Laplace’s concept is being applied in the research and development programme into the mathematical modelling of spacer bandages to achieve the required pressure mapping for the treatment of venous leg ulcers at the University of Bolton.
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7.00
Pressure transference (mm Hg)
6.00 5.00 4.00 7.3 (mm Hg) 14.6 (mm Hg) 21.9 (mm Hg) 29.3 (mm Hg) 36.6 (mm Hg) 43.9 (mm Hg) 51.2 (mm Hg) 58.6 (mm Hg)
3.00 2.00 1.00 0.00
0
10
20
30
40
50
60
70
80
90
100
110 120
Fabric extension (%)
6.6 Effect of extension on pressure transference of spacer bandages – black (1).
4.50
Pressure transference (mm Hg)
4.00 3.50 3.00 2.50
7.3 (mm Hg) 14.6 (mm Hg) 21.9 (mm Hg) 29.3 (mm Hg) 36.6 (mm Hg) 43.9 (mm Hg) 51.2 (mm Hg) 58.6 (mm Hg)
2.00 1.50 1.00 0.50 0.00
0
10
20
30
40
50
60
70
80
90
100
Fabric extension (%)
6.7 Effect of extension on pressure transference of spacer bandages – white (2).
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Pressure transference (mm Hg)
6.00 5.00 7.3 (mm Hg) 14.6 (mm Hg) 21.9 (mm Hg) 29.3 (mm Hg) 36.6 (mm Hg) 43.9 (mm Hg) 51.2 (mm Hg) 58.6 (mm Hg)
4.00 3.00 2.00 1.00 0.00
0
10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 Fabric extension (%)
6.8 Effect of extension on pressure transference of spacer bandages – white (3).
10.00
Pressure transference (mm Hg)
9.00 8.00 7.00 6.00 7.3 (mm Hg) 14.6 (mm Hg) 21.9 (mm Hg) 29.3 (mm Hg) 36.6 (mm Hg) 43.9 (mm Hg) 51.2 (mm Hg) 58.6 (mm Hg)
5.00 4.00 3.00 2.00 1.00 0.00
0
10
20
30
40
50
60
70
80
90
Fabric extension (%)
6.9 Effect of extension on pressure transference of spacer bandages – blue (4).
Advanced textiles for wound compression
6.8
175
Conclusions
Compression-delivery systems have an important role in the treatment of venous leg ulceration since they can reduce venous reflux, increase venous and arterial blood flow, improve microcirculation, and reduce ankle oedema. There is a variety of compression bandaging systems available, the advantages and disadvantages of each are constantly reviewed and debated. In the UK, for example, a four-layer bandaging system is popular and has been shown to provide a safe and effective treatment option. Other countries, such as the USA, prefer the rigid characteristics of the Unna’s Boot. The success of any compression bandage system relies upon the skill and expertise of the clinician applying it. Moreover, the effective management of venous leg ulcer involves careful selection of bandages to reverse the venous blood flow back to the heart. The contribution of padding as well as compression bandages in healing the ulcer is significant. The advantages and limitations of the existing two-layer and four-layer bandaging regimens have been discussed. It is obvious that the pressure transference of commercial padding bandages varied and none of the padding bandages investigated satisfied the requirements of an ideal padding bandage. On the other hand, the novel padding bandages exhibited a uniform pressure distribution around the leg. The paper also demonstrated the need for developing a single-layer bandaging regime for the benefit of the elderly and to cut the cost of treatment. The use of 3D spacer technology has been investigated and the results affirmed that spacer bandages would be utilised to design and develop a single-layer system that could replace the currently used cumbersome four-layer system. A suitable spacer structure can combine the desirable attributes of both the padding and two-dimensional compression bandages into one composite three-dimensional structure.
6.9
References
1. reichenburg, j., davis, m. Venous Ulcers. Semin Cutan Med Surg 2005; 24(4): 216–226. 2. martson, w.a., carlin, r.e., passman, m.a., farber, m.a., keagy, b.a., parent iii, f.n. Healing rates and cost efficacy of outpatient compression treatment for leg ulcers associated with venous insufficiency. J Vasc Surg 1999; 30(3): 491–498. 3. sarkar, p.k., ballentyne, s. Management of leg ulcers. Postgrad Med J 2000; 76: 674–682. 4. nicholaides, a.n. Investigation of chronic venous insufficiency: a consensus statement (France, March 5–9, 1997). Circulation 2000; 102(20): E126– E163.
176
Advanced textiles for wound care
5. margolis, d.j., bilker, w., santanna, j., baumgarten, m. Venous leg ulcer: incidence and prevalence in the elderly. J Am Acad Dermatol 2002; 46(3): 381–386. 6. naschitz, j.e., yeshurun, d., misselevich i., boss j.h. The pathogenesis of lipodermatosclerosis: facts, uncertainties and theories. J Eur Acad Dermatol Venereol 1997; 9(3): 209–214. 7. zimmet, s.e. Venous leg ulcers: modern evaluation and management. Dermatol Surg 1999; 25(3): 236–241. 8. franks, p.j., moffatt, c.j., bosanquet, n., oldroyd, m., greenhalgh, r.m., mccollum, c.n. connolly, m. Community leg ulcer clinics: effect on quality of life. Phlebology 1994; 9(2): 83–86. 9. london, n.j.l., donnelly, r. Ulcerated lower limb. BMJ 2000; 320: 1589–1591. 10. sibbald, r.g. Venous leg ulcers. Ostomy Wound Manage 1998; 44(9): 52–64. 11. sumner, d.s. Non-invasive assessment of peripheral arterial occlusive disease. In: Rutherford, K.S, editor. Vascular Surgery (3rd edition) Philadelphia: WB Saunders, 1998; 41–60. 12. callam, m.j., ruckley, c.v., harper. dale, j.j. Chronic ulceration of the leg: extent of the problem and provision of care. Br Med J (Clin Res Ed) 1985; 290(6485): 1855–1856. 13. mcguckin, m., stineman, m., goin, j., williams, s. Draft guideline: diagnosis and treatment of venous leg ulcers. Ostomy Wound Manage 1996; 42(4): 48–54. 14. valencia, i.c., falabella, a., kirsner, r.s. eaglstein, w.h. Chronic venous insufficiency and venous leg ulceration. J Am Acad Dermatol 2001; 44(3): 401–424. 15. blair, s.d., wright, d.d.i., backhouse, c.m., riddle, e., mccollum, c.n. Sustained compression and the healing of chronic ulcers. BMJ 1988; 297: 1159–1161. 16. cullum, n., nelson, e.a., fletcher, a.w., sheldon, t.a. Compression for venous leg ulcers. Cochrane Database Syst Rev 2004; (2): CD000265. 17. choucair, m., phillips, t.j. Compression therapy. Dermatol Surg 1998; 24(1): 141–148. 18. partsch, b., partsch, h. Calf compression pressure required to achieve venous closure from supine to standing positions. J Vasc Surg 2005; 42(4): 734–738. 19. partsch, h. Do we still need compression bandages? Haemodynamic effects of compression stockings and bandages. Phlebology 2006; 21(3): 132–138. 20. thomas, s. Bandages and bandaging: the science behind the art. Care Sci Pract 1990; 8(2): 56–60. 21. simon, d. Approaches to venous leg ulcer care within the community: compression, pinch skin grafts and simple venous surgery. Ostomy Wound Manage 1996; 42(2): 34–40. 22. anon. The complete Scholl guide to health care for legs. Luton: Scholl, 1996. 23. hach-wunderle, v. düx, m., hoffmann, a., präve, f., zegelman, m., hach, w. Treatment of deep vein thrombosis in the pelvis and leg. Deutsch Ärztebl 2008; 105: 23–34.
Advanced textiles for wound compression
177
24. polignano, r., guarnera, g., bonadeo, p. Evaluation of SurePress comfort: a new compression system for the management of venous leg ulcers. J Wound Care 2004; 13(9): 387–391. 25. british standards institution. Specification for graduated compression hosiery. BS 6612:1985; London: BSI, 1985. 26. certificat de qualite-produits. Referentiel technique prescrit pourles ortheses elastiques de contention des membres. 1999; Paris: ASQUAL. 27. deutsches institut für gütesicherung und kennzeichnung. Medizinische Kompressionsstrümpfe RAL-GZ 387. 2000; Berlin: Beuth. 28. clark, m., krimmel, g. Lymphoedema and the construction and classification of compression hosiery. Lymphoedema Framework. Template for Practice: compression hosiery in lymphoedema. 2006; London: MEP Ltd. 29. williams, c. Leg ulcer after care: the role of compression hosiery. Br J Nurs 2000; 9(13): 822–828. 30. vowden, k.r., vowder, p. Preventing venous ulcer recurrence: a review. Int Wound J 2006; 3(1): 11–21. 31. nelson, e.a., bell-syer, s.e.m., cullum, n.a. Compression for preventing recurrence of venous ulcers. Cochrane Database System Rev 2000; (4): CD002303. DOI: 10.1002/14651858.CD002303. 32. partsch, h. Compression therapy of the legs: a review. J Dermatol Surg Oncol 1991; 17(10): 799–805. 33. depalma, r.g., kowallek, d., spence, r.k. Comparison of costs and healing rates of two forms of compression in treating venous ulcers. Vasc Surg 1999; 33(6): 683–690. 34. hampton, l. Venous leg ulcers: short stretch bandages for compression therapy. Br J Nurs 1997; 6(17): 990–998. 35. rajendran, s., anand, s.c. Design and development of novel bandages for compression therapy. Br J Nurs (Tissue Viability Supplement) 2003; 12(17): S20–S29. 36. rajendran, s., anand, s.c. Development of novel bandages for compression therapy, Wounds UK 2002, Harrogate, 19–20 November 2002. 37. gibson, b., duncan, v., armstrong, s. Know how: ischaemic leg ulcer. Nurs Times 1997; 93(36): 34–36. 38. moffat, c., harper, p. Leg ulcers. Churchill Livingstone, Edinburgh, 1997. 39. stemmer, r. Ambulatory-elasto-compressive treatment of the lower extremities particularly with elastic stockings. Derm Kassenarzt 1969; 9: 1–8. 40. logan, r.a., thomas, s., harding, e.f., collyer, g. A comparison of sub-bandage pressures produced by experienced and inexperienced bandagers. J Wound Care 1992; 1(3): 23–26. 41. simon, d.a., freak, l., williams, i.m. et al. Progression of arterial disease in patients with healed venous ulcers. J Wound Care 1994; 3(4): 179–180. 42. moffatt, c.j., dickson, d. The Charing Cross high compression four-layer bandaging system. J Wound Care 1993; 2(2): 91–94. 43. nelzen, o., bergqvist, d., lindhagen, a. Leg ulcer etiology – a cross sectional population study. J Vasc Surg 1991; 14(4): 557–564.
178
Advanced textiles for wound care
44. buchbinder, d., mccullough, g.m., melick, c.f. Patients evaluated for venous disease may have other pathological considerations contributing to symptomatology. Am J Surg 1993; 166: 211–215. 45. cullum, n., nelson, e.a., fletcher, a.w. sheldon, t.a. Compression for venous leg ulcers. Cochrane Database System Rev 2001; (2): CD000265. DOI:10.1002/ 14651858.CD000265. 46. nhs centre for review and dissemination. University of York. Compression therapy for venous leg ulcers. Effect Healthcare 1997; 3(4): 1–12. 47. rajendran, s., anand, s.c. The contribution of textiles to medical and healthcare products and developing innovative medical devices. Indian J Fibre Text Res 2006; 31: 215–229. 48. rajendran, s., anand, s.c. Challenges in development of woundcare medical devices, FiberMed 06, Tampere, Finland, 7–9 June, 2006. 49. anand, s.c. Spacers – at the technical frontier. Knit Int 2003; 110: 38–41. 50. anon. Spacer fabric focus. Knit Int 2002; 109: 20–22.