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Compression hosiery for venous leg ulceration

Therapeutic compression is a keystone in the management of venous leg ulceration and can be delivered using bandaging or hosiery. Una Adderley explains how compression hosiery works and when it should be used

Una Adderley
DN RGN MSc BSc BA
Community Tissue Viability Prescribing Nurse
North Yorkshire and York PCT

Compression hosiery is the term used for stockings, tights or socks that are designed to apply therapeutic compression to the lower limbs. Therapeutic compression may be prescribed for a variety of clinical indications. It can be an effective intervention for reversing venous hypertension to promote healing of venous leg ulceration or to reduce the risk of leg ulcer recurrence. Therapeutic compression may also be prescribed to manage lower leg lymphoedema or to reduce the risk of thrombus formation, but this article will focus on the use of compression hosiery around venous leg ulceration.

What is venous leg ulceration?
The British Association of Dermatologists defines a venous leg ulcer as "an open sore in the skin of the lower leg due to high pressure of the blood in the leg veins".(1) Venous leg ulceration occurs when the venous circulation is compromised by failures within the deep, superficial or perforator vein systems that enable venous return from the feet and legs. These systems contain valves that allow blood to flow up towards the heart and prevent back flow down the leg. Blood flows towards the heart in response to increased pressure from the pumping of the heart, combined with the calf and foot pump mechanisms, which function when the ankle is flexed, such as during walking. When the valves are faulty they allow the backward flow of blood down the leg, which leads to increased pressure within the veins. This damages tiny blood vessels in the skin, which becomes vulnerable and may eventually break down spontaneously or fail to heal following an injury. The resulting open lesion is known as a venous leg ulcer. 
Venous leg ulceration is relatively common. Between 1% and 2% of the total adult population will experience venous leg ulceration at some stage in their lives, and between 0.1% and 0.2% of the total adult population will have an open ulcer at some point in time with increased prevalence in the older population. Some people are born with poor valves, while some acquire valve damage following venous thrombosis (a blood clot that forms within a vein) or as a result of reduced mobility or aging.(2)
 
The role of compression in venous leg ulceration
There is robust research evidence in favour of graduated multilayer high compression systems for healing venous leg ulcers that are not complicated by arterial insufficiency (with an ABPI [ankle brachial pressure index] greater than 0.8). Graduated multilayer high compression systems include bandaging systems such as four layer bandaging, short stretch bandaging and compression hosiery. Better healing rates are associated with high compression systems compared with low compression systems, but there is no reliable evidence that any particular high compression system is better than another.(3)
Venous leg ulceration is a long-term chronic condition and between 59% and 67% of patients will experience recurrence following healing.(4) Therefore prevention of recurrence is important and evidence and expert opinion suggest that wearing compression hosiery reduces ulcer recurrence.(5,6) 
Both compression bandaging systems and compression hosiery systems are based on the concept that graduated compression encourages the return of blood to the heart and the return of lymph to the lymph nodes, thus restoring balance in the skin. The term "graduated" refers to the fact that when the bandaging or stocking is correctly applied, there will be greater pressure at the ankle than at the calf (and greater pressure at the calf than at the thigh). It is thought that for elastic compression systems, the optimum pressure for promoting healing is 40 mmHg at the ankle.  
Compression bandaging has traditionally been the treatment choice for healing venous leg ulceration with compression hosiery reserved for prevention of recurrence. However, this distinction is not clear cut. Some patients with healed leg ulceration are unable to tolerate compression hosiery or can only maintain healing in compression bandaging. Furthermore, the recent introduction of compression hosiery kits designed to achieve healing offers an alternative to bandaging systems in terms of ulcer healing, although as yet, no robust research evidence exists to compare their effectiveness with that of bandaging systems.
Before using any compression system, it is essential to establish whether the patient has sufficient arterial supply to cope with the application of compression. The application of compression therapy to an arterially impaired limb can result in pressure damage, limb ischaemia and even amputation. All patients should receive Doppler ultrasound measurement of ABPI (ankle brachial pressure index) to check for arterial insufficiency. Doppler assessment should be repeated when: an ulcer is deteriorating; if an ulcer has not fully healed by 12 weeks; if an ulcer recurs; if new symptoms present that suggest arterial insufficiency; and three monthly as part of ongoing assessment.(6)
If the patient has an adequate arterial supply, then the decision to use compression hosiery or compression bandaging will depend on a variety of factors. Compression hosiery systems are reasonably straightforward to apply compared with bandage systems, which demand much higher levels of skill and judgment from the clinician. Poorly applied bandaging is potentially dangerous as it can lead to pressure damage and compromised circulation.
Compression hosiery systems can also have huge quality-of-life benefits for patients - they may enable many patients to apply their own compression and thus regain some control over their own care. Furthermore, since hosiery is slimmer than bandaging systems, patients should be able to fit into their usual footwear and their mobility may increase as a result. Some patients will find compression hosiery more comfortable than compression bandaging and most will view compression hosiery as more aesthetically pleasing than compression bandaging.  
However, a venous leg ulcer with copious exudate will require the absorbency of the wadding layer of a multilayer compression bandage system, at least until the venous hypertension has been controlled and exudate levels have reduced. Patients with very bony prominences may risk pressure damage from compression hosiery, whereas the wadding in multilayer bandage systems can be tailored to the individual anatomy of each patient. 
Hosiery is classified according to the level of compression achieved at the ankle. However, the classification system is potentially very confusing since in the UK compression hosiery is classified using two separate systems: the British Standard Class compression system or the European Class compression system (see Table 1).

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In the community, the most commonly prescribed compression hosiery for venous leg ulceration is classified using British Standard Class compression system. However, in secondary care, European Class compression is often prescribed for venous hypertension. Therefore when a patient is prescribed compression hosiery via an outpatient clinic it is important to establish exactly what has been prescribed, as "hospital class 2" may differ significantly from "community class 2". Compression hosiery for lymphoedema has recently become available on the Drug Tariff, but is classified using the European classification levels. Again, it is essential to clarify exactly what level of compression has been prescribed in order to promote continuity of care.
If graduated compression hosiery is to be effective, it must be the correct size in order to be comfortable and to apply the right amount of pressure. Careful measurements should be taken in order to determine the appropriate size of the garment. Many patients with venous hypertension will experience worsening ankle oedema during the day so it is best to measure the limbs in the morning and, if possible, to have the patient standing. 
For most patients, below-knee compression is sufficient to reverse venous hypertension, but if the patient has significant varicose veins behind the knees, they may find thigh-length hosiery more comfortable. It is usual to measure around the narrowest part of the ankle and the widest part of the calf (and also thigh if thigh-length hosiery is being prescribed), but to note if the patient has exceptionally long or small feet. These measurements should then be considered in relation to the hosiery manufacturers' sizing chart.
Selecting the appropriate size of hosiery is complicated. At present there is no standard sizing system and a patient's leg dimensions may require size "small" in one make, but size "medium" in another. Although this adds complexity to prescribing there are some advantages. Since all British Standard Class compression hosiery costs the same on the Drug Tariff, there is no incentive to choose the cheapest make. Therefore the variety on offer means most patient dimensions can be met within the ready-to-wear range. If, however, the patient has exceptionally large or small ankles, they may require made-to-measure hosiery (which is also available on prescription). 
Whether compression hosiery is being prescribed to heal leg ulceration or to prevent recurrence, it is essential that the patient is comfortable. Although the evidence suggests that higher compression levels are associated with higher levels of healing or prevention of recurrence, it is also recognised that if hosiery is too uncomfortable or difficult to apply then patients simply will not wear it. Therefore, the current advice is that patients with adequate arterial supply should be encouraged to wear British Class 3 compression hosiery if they can tolerate it; otherwise they should be prescribed the highest level of compression that they can tolerate.

Conclusion
Compression hosiery is a hugely complex subject and this article can only act as an introduction. However, since adequate compression can have such a major impact on patients' quality of life, healing rates, recurrence rates and costs to healthcare providers in terms of nursing time saved and the reduction in dressing costs, clinicians working with patients with leg ulcers have a duty to develop advanced skills and knowledge in this area.

References

  1. British Association of Dermatologists. Venous leg ulcers. London: BAD; 2004. Available from: http://www.bad.org.uk/public/leaflets/venous.asp
  2. Morison M, Moffatt C. Causes of leg ulcers. A colour guide to the assessment and management of leg ulcers. 2nd ed. London: Mosby; 1994.
  3. Cullum N, Nelson EA, Fletcher AW, Sheldon T. Compression for venous leg ulcers. Cochrane Database Syst Rev 2001;2:CD000265.
  4. Briggs M, Closs J. The prevalence of leg ulceration: a review of the literature. EWMA J 2003;3:14-20.
  5. Vandongen YK, Stacey MC. Graduated compression elastic compression stockings reduce lipodermatosclerosis and ulcer recurrence. Phlebology 2000;15:33-7.
  6. Royal College of Nursing. The management of patients with venous leg ulcers. London: RCN; 2006.


Resource

RCN Clinical Guidelines
W: www.rcn.org.uk/development/practice/clinicalguidelines/venous_leg_ulcers