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All you need to … leg ulcers

Leg ulcers are a major problem to both the patients and health services. Maureen Benbow discusses the pathophysiology of leg ulceration, diagnostic investigations, evidence-based management and prevention of recurrence

Maureen Benbow
MSc BA RGN HERC
Senior Lecturer University of Chester

It is universally agreed that the key to successfully treating any wound is thorough patient and wound assessment. This is even more important when managing patients presenting with a wound on their lower leg as mismanagement can result in serious complications or even amputation. With over 40 recognised underlying causes of leg ulceration the most common underlying problems are alteration to blood flow or inadequate blood flow.(1) Patients with leg ulceration are mainly treated in the community setting, but more frequently are attending secondary care for treatment or hospitalisation.(2)

Background
Leg ulcers remain a major problem to both patients and health services, but little is known about the size and the cost of this problem. The use of unclear operational definitions within studies and the methods of measurement create difficulties in prevalence estimation.(3) However, estimates of point prevalence of patients with open ulcers ranges from 0.1% to 0.3%, and 1-2% of the population will suffer from leg ulceration overall.(3) There are between 70,000 and 190,000 people with an active ulcer at any given time in the UK, which is likely to increase as the population ages.(1) Over 85 years of age the ratio of venous leg ulceration increases to 1:10.3 male to female; this is attributed to the fact that women live longer than men and the increased risk of deep vein thrombosis during pregnancy in women.(4) Further inaccuracies relate to the number of people with leg ulceration who self-treat and are therefore unknown to healthcare services.
It was estimated that chronic wounds, including leg ulcers, cost the UK over £ 1bn a year, with venous leg ulceration estimated to cost the NHS £400m.(5-7) This figure has been reviewed and is now estimated to be around £200m a year.(1) The management of patients with leg ulcers is time-consuming and long term with the cost of nursing care accounting for a large proportion of the expenditure. Other costs are associated with the high recurrence rate of venous leg ulcers despite the standard treatment of graduated compression therapy, leg elevation and exercise, and compression stockings. Soloway found a 26-28% recurrence rate for venous leg ulcers at one year.8 There are also the psychological and social costs to the patient as it is now well-recognised that leg ulceration causes pain, affects sleep, restricts mobility and adversely affects self-esteem, possibly resulting in depression, emotional reactions and social isolation.(9-13)

Leg ulcer pathophysiology
Leg ulcers are chronic wounds arising from predisposing conditions that impair the ability of the tissue to maintain its integrity or heal damage.(14) The most common are venous (37-81% depending on the diagnostic methods used), arterial (10%) and mixed venous and arterial (7%), while others may result from diabetes, rheumatoid arthritis or malignancy.(15) Patients can have leg ulcers with a single aetiology or with multiple causes. Other causes include injuries leading to traumatic ulcers, certain skin conditions, tumours and infections.
Accurate identification of the pathophysiology of venous leg ulceration is elusive, and various theories have been proposed to attempt to explain why it happens. It is widely accepted that it results from underlying chronic venous hypertension leading to venous insufficiency, sometimes secondary to damage to the venous system following deep vein thrombosis. The damage to the valves in the deep veins permits blood returning to the heart to flow backwards or in the wrong direction. Other explanations include the fibrin cuff theory, white cell trapping theory and chronic inflammation due to ischaemia reperfusion injury. The fibrin cuff theory suggests that venous hypertension allows fibrin to escape through the capillary wall preventing oxygen and nutrients from reaching the tissues and waste being carried away.(16) The white cell trapping theory assumes that the white cells damage the cell wall and larger molecules are released from the capillaries.(16) Each theory is proposed in an attempt to explain the skin and tissue changes associated with leg ulceration. Neither theory, however, satisfactorily explains why leg ulcers occur, but treatment is aimed at correcting or avoiding venous hypertension and compensating for venous incompetence.(1)
Arterial leg ulceration results from reduced arterial circulation that interferes with normal cell metabolism and leads to local and limb ischaemia. Common causes include atherosclerotic changes in the main vessels and small emboli (blockages), not uncommonly the result of hypertension.
 
Contributing factors
In patients with venous ulcers there may be a history of varicose veins, deep vein thrombosis or phlebitis, previous fracture, trauma or surgery and/or a family history of venous disease. Symptoms of venous insufficiency include leg pain, heavy legs, aching, itching, swelling, skin breakdown, pigmentation and eczema. While in nonvenous disease there may be a history of ischaemic heart disease, stroke, transient ischaemic attack, peripheral vascular disease/intermittent claudication, cigarette smoking, diabetes or rheumatoid disease.(15) Other factors that have been linked to leg ulceration are raised BMI, number of pregnancies, standing for long periods and straining at stool.(17) However, there is no conclusive evidence that these underlying conditions are directly linked as causal factors for leg ulceration as many people have these conditions and never develop leg ulceration.
The incidence of intermittent claudication, critical ischaemia and leg ulceration increases with age, and many leg ulcer patients are elderly females with a history (or undetected) deep vein thrombosis or varicose veins in pregnancy.(18) Venous stasis secondary to leg ulceration can often be traced back to occupations that involve prolonged standing. Patients with leg ulceration spend long periods at home with their legs dependent, which contributes to poor venous return and results in swelling. Assessment of ankle mobility is important to ascertain the ability to use the calf muscle pump to aid venous return.(19)
It has been noted that many leg ulcer patients are grossly overweight, which reduces mobility and induces strain on the ulcerated limb, while poor diet hinders the healing process.(20,21) Nutritional assessment will reveal whether there should be any concerns about appropriate nutritional intake. Weight reduction may be indicated in the obese and morbidly obese patient to aid mobility and thus improve perfusion locally and systemically. Smoking is known to exacerbate arterial constriction and will delay healing.(22,23) The patient's past medical history and medications will also provide clues to leg ulcer aetiology.
Patients with leg ulceration will normally experience pain of differing types, and the pain may be restricted to the ulcer or throughout the leg. One significant characteristic of arterial ulceration is pain, which is experienced on elevation and at night when in bed, and can only be relieved by hanging the leg over the side. Pain on walking in the calf, thigh or buttock, which is relieved by resting, is also indicative of arterial disease. Pain in venous disease is relieved by elevation, and the associated night cramps improved by walking about.
The assessment should also identify any psychological or social factors that could have an impact on treatment, concordance and quality of life as well as the patient's understanding of the disease process.

Patient assessment
A thorough assessment to determine the underlying aetiology is the first step towards identifying why the patient has a nonhealing wound. This can only be determined through a full clinical history together with a physical examination, as well as appropriate laboratory tests and haemodynamic assessment.(24,25) Visual assessment alone cannot diagnose a leg ulcer; just as an assessment without Doppler ultrasound studies to determine ulcer aetiology is potentially hazardous.(26-29) The most important part of the assessment is exploring possible contributing factors within the patient; the wound assessment is secondary to this process.
Basic biographical information and details of the patient's general medical condition, medications, lifestyle, limitations, pain and attitude to having a chronic wound are all important issues to assess. Physical examination consists of an assessment of both lower limbs (irrespective of whether both have ulceration), together with Doppler ultrasound assessment. Finally, the ulcer should be examined.

Assessment of both limbs
It is important that both legs are examined lying and standing. Doppler ultrasonography is used to assess the blood supply to the lower leg. The handheld Doppler to record the patient's ankle/brachial pressure index (ABPI) in both legs forms the basis of arterial assessment, but can only be used as part of the holistic assessment. Doppler assessment is not a diagnostic tool, but helps to screen those patients with any degree of arterial impairment for whom compression therapy would not only be inappropriate but potentially hazardous. The ABPI for each leg is calculated by dividing the highest of the ankle pressures by the higher of the two brachial pressures. Service guidelines tend to recommend that a patient with an ABPI of less than 0.8 should be referred for a further vascular assessment; an ABPI of Assessment of the skin combined with patient report can provide useful information about allergies, sensitivities and compliance to proposed therapy; contact dermatitis is a problem commonly associated with leg ulceration.(30)

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Wound management
A clear understanding of the aetiology of the ulcer and physiology of wound healing, the appropriate therapy and type of dressing, and patient acceptance in each specific stage of the condition can make or break the therapeutic process. The principles of wound management must be followed, and can be summarised using the acronym TIME:(31)
Tissue: Is the tissue nonviable or deficient? The dressing selected should manage exudate levels, support healing and be acceptable to the patient. Necrotic tissue or slough in the wound is an ideal environment for the proliferation of bacteria and its presence is believed to impede the growth of granulation tissue and, therefore, healing.(32) This material must be removed using dressings (promoting autolysis), sharp debridement or larval therapy.
Infection or inflammation: a clean dressing technique must be employed, but tap water may be used for cleansing the wound and leg in the home. Sterile primary dressings, however, are the norm and, if strike-through occurs, the dressings/bandages should be changed as soon after as is reasonable to prevent the passage of pathogens to the wound. Rising exudate levels may indicate infection particularly in an elderly person. Appropriate systemic antibiotic therapy will be necessary plus the use of topical antimicrobial dressings to treat the infection if appropriate.
Moisture imbalance: optimum moisture balance will increase cell proliferation, decrease inflammation and enhance re-epithelialisation. Foam, alginate or hydrofibre dressings absorb large amounts of exudate.
Edge of wound: undermining of the wound edge or lack of advancement of the wound edge may be a result of poor fibroblastic activity, vascular deficiency or impaired re-epithelialisation. If the wound is failing to improve with standard care, it might be necessary to refer to secondary care for possible advanced interventions such as to surgically trim the wound edge, or use skin grafting or a human dermal substitute to promote healing.
When a venous leg ulcer has been confirmed the priorities for care will be:

  • Compression therapy in the form of multilayer, graduated compression bandages or hosiery to counteract abnormal internal venous pressures. External bandage pressures of 40 mmHg are needed to manage venous ulceration, but these should only be applied by a trained, competent practitioner.(33) Short-stretch bandage systems or compression hosiery may be suitable options for those unable to tolerate the multilayer bandage systems in patients that are mobile. Ideally, compression bandages should be left in place for a week so; on removal, the leg should be washed with warm tap water and the skin moisturised to prevent the build-up of dry, scaly skin.
  • To manage the underlying venous disease, if possible with medication or surgery.
  • Control oedema with exercise (which should be encouraged in able patients) and elevation above the heart when sitting, providing that the patient does not suffer from a cardiac or pulmonary condition, and is able to tolerate it. Podiatry care may be needed to remove callosities or suggest ways of correcting other mechanical factors that interfere with walking. 
  • Care of the surrounding skin; known sensitisers should be avoided; low allergy emollients such as soft white paraffin/liquid paraffin 50/50 should be applied to keep the skin hydrated and aid removal of skin scales after washing.
  • Patient compliance - many patients have difficulty adjusting to thick, hot, tight bandaging and resent not being able to wear their normal shoes for the sake of a small ulcer. This will, in turn, affect their compliance with treatment. They should be given verbal and written information to help them to understand why the treatment and prevention of recurrence is so important to them.
  • Nutritional assessment, which will reveal whether there should be any concerns about appropriate nutritional intake. Weight reduction may be indicated in the obese and morbidly obese patient to aid mobility and thus improve perfusion locally and systemically.
  • To discourage smoking, as it is known to impede healing. The carbon monoxide binds to haemoglobin instead of oxygen, significantly reducing the amount of circulating oxygen.(23)

Ongoing assessment will include measurement and tracing of the wound at one to two-weekly intervals and photographs if possible. Compression therapy is the "gold standard" treatment for healing leg ulceration so patients should be encouraged to persist with their treatment both during and after healing for best results. Recurrence rates are very high so patients with healed ulcers should be reviewed at regular intervals to check for vascular deterioration and whether they are complying with wearing compression hosiery.

Recurrence of leg ulceration
A major problem associated with leg ulcers is the high recurrence rate. As we become more proficient at healing leg ulcers, the rate of recurrence increases. The rate is estimated at 26% at one year and 31% at 18 months.(34) Recurrence rates may be reduced if higher compression is used, but there is little evidence.35 The introduction of Leg Clubs has illustrated dramatic reductions in both nonconcordance and posthealing recurrence combined with significant savings compared with conventional home visits.36 The philosophy behind such clinics promotes a social rather than medical environment in which patients are empowered to participate and take ownership of their problem and gain peer support from others in similar situations. The evidence of high recurrence is recognised and any initiative that promotes patient "power" as well as improved outcomes must be applauded.

Conclusion
Many venous leg ulcers would heal if the patient was confined to bed with their legs elevated for the duration, but this is neither cost-effective nor practical in times of bed shortage and other constraints on healthcare funding. The care of patients with venous leg ulceration is rightly placed in the community where individuals can retain some independence and quality of life. Leg ulcers are not going to disappear, but many of the problems associated with them can be managed more cost-effectively and effectively using the skills of leg ulcer and tissue viability nurse specialists and their teams.

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