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Risk factor assessment for patients with peripheral arterial disease

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Sharon Goodall, BSc (Hons), RN, Dip (HE), PGCert (Research).

Vascular Nurse Consultant, Burnley Healthcare NHS Trust, Burnley, Lancashire

It is estimated that 50 000 patients a year in England and Wales are admitted to hospital for the treatment of peripheral arterial disease (PAD) (Fowkes, 1988). The symptoms of PAD include intermittent claudication (a cramping pain in the leg), rest pain and critical limb ischaemia. In a population survey of people aged between 55 and 74 years, 4.5% had symptomatic claudication and 8% had major asymptomatic disease (Leng et al, 1996).

The presence of PAD leads to a significant risk of other conditions caused by vascular ischaemia, including increased all-cause mortality, increased cardiovascular mortality and increased non-fatal cardiovascular events. The condition also limits functional independence. Therefore, a major factor to consider when treating patients with PAD is the implementation of measures to reduce the progression of arteriosclerosis, a degenerative arterial disease. The benefits of assessing and managing cardiovascular risk factors in this patient group (Shearman and Chulakadabba, 1999) include:

- Reduced cardiovascular mortality and morbidity

- Preventing deterioration of the local disease

- Improving the long-term benefit of revascularisation procedures.

However, widespread application of medical management has often been limited by:

- Lack of direct evidence of benefit

- Problems with patient compliance

- Cost-effectiveness.

Responsibility for the assessment and subsequent treatment of this patient group lies with a variety of health professionals in both primary and secondary care settings. Developments such as the National Service Framework for Coronary Heart Disease (DoH, 2000), the national treatment guidelines from groups such as the British Hypertension Society (1999), and government health targets will have an impact on services. Health professionals cannot ignore their responsibility to ensure that patients with PAD receive the appropriate interventions and education regarding this disease. Nurses in all areas, including practice nurses, ward-based vascular nurses and vascular nurse specialists, play an essential role in health education. All nurses need to have an awareness of the risk factors and, along with other members of the vascular team, take on the challenge of risk-factor management for these patients.

Atherosclerosis

Atherosclerosis is a complex and insidious condition and one of the primary causes of death in the UK. Fatty material (plaque) is deposited in the lining of medium- and large-sized arteries. This plaque protrudes into the artery lumen, which consequently narrows (stenosis). Some degree of PAD is potentially present in most of the adult population (Beaver, 1986). The major arteries in the lower limbs are usually affected. In approximately 90% of cases, atherosclerosis is insidious, with no symptoms presenting for about a decade after onset (Camilleri et al, 1989).

Intermittent claudication

Reduced blood supply to the lower limbs and effort-related cramp in the calves, thighs and buttocks, which disappears at rest, is known as intermittent claudication (Dumas, 1995). The pain, muscular in origin, is the result of reduced blood flow and inability of the collateral circulation to meet the oxygen demands of the exercising muscles (Dumas, 1995). Intermittent claudication is experienced by approximately 50% of patients whose arteries have narrowed by 60% or more (Hiatt, 1998) and is the commonest manifestation of PAD (Ruckley, 1986).

Many adults have some degree of atherosclerosis on reaching middle age. An estimated 5% of males and 2.5% of females aged over 50 years are affected by intermittent claudication (Ruckley, 1986; Jelnes et al, 1986; Reunanen et al; 1982). In only 1% of this group will the disease progress to necessitate limb amputation and, for about 70%, symptoms will remain stable or improve at five years (Cronenwett, 1980). The life expectancy of patients with PAD is, however, characterised by a two- to three-fold excess mortality (Jager and Ricketts, 1985), and death in about 80% of cases occurs as a result of myocardial infarction and cerebrovascular disease (Kannel and McGee, 1985).

Treatment options

Options for treating intermittent claudication include drug therapy, percutaneous transluminal angioplasty (PTA), bypass surgery and lifestyle modification. Surgical and radiological interventions can be costly both in financial terms, and with regard to their impact on quality of life, and they are not without risk. Therefore lifestyle advice, summed up as ‘stop smoking and keep walking’ (Housley, 1988), is often the preferred treatment plan (Khaira et al, 1996; Coffman, 1991).

A major obstacle to successful long-term lifestyle intervention is the achievement of adequate patient compliance. To achieve successful therapeutic outcomes in terms of smoking cessation and adherence to lipid-lowering, antiplatelet, antihypertensive and diabetic treatments, a trusting, long-term relationship between the vascular team and the patient is essential. In order to motivate the patient, nurses need to provide guidance, explain the rationale for the required changes in lifestyle and offer specific tools to help. The patient’s psychosocial state should also be considered at the initial assessment, as responses to diagnosis and chronicity of vascular disease vary among patients and their families and may affect an individual’s ability to adapt to altered function and adhere to treatment (Fahey, 1999).

Risk factors

The atherosclerosis risk profile of individuals with PAD is similar, but not identical, to that of those with other forms of atherosclerosis associated with cerebral and cardiovascular events. Nurses need to explain the reasons for risk factor assessment and emphasise that PAD is associated with tangible risks of other vascular ischaemic events and deaths. An assessment of the patient should include documenting existing risk factors and current treatments. Risk assessment is discussed in Box 1.

The nurse should then focus on determining the patient’s goals and expectations regarding lifestyle changes. For some patients, the incentive for lifestyle modification may be a desire to avoid surgery, or to ensure that the disease does not deteriorate. Goals have to be specific, measurable, achievable, realistic and set within a suitable timeframe (SMART). The initial assessment of all the risk factors takes time - approximately one hour - and will require regular follow-up to aid the evaluation and setting of new goals. The rationale for assessment of each risk factor is given below and should be explained in terms understood by the patient to aid understanding and adherence to recommendations.

Cigarette smoking - Smoking damages the vascular endothelium and accelerates the rate of atherosclerosis progression (Ekers and Hirsch, 1999). Smoking is the single most important risk factor for PAD. Each year smoking causes more than 120 000 deaths in the UK and remains the largest single preventable cause of death and disability in the country, costing the NHS about £1500 million a year (Parrott et al, 1998). Approximately 70-90% of people with intermittent claudication smoke or are ex-smokers (Belch et al, 1984). Smoking tobacco increases the risk of developing atherosclerotic plaques. Continuing to smoke worsens the outcome of vascular interventions (Krupski, 1991).

Nurses play a crucial part in helping to improve rates of long-term tobacco abstinence and should educate patients about the effects of smoking on the arterial system. Nicotine causes constriction of the blood vessels, which leads to a further reduction in blood flow. The carbon monoxide in cigarettes replaces the oxygen in red blood cells and the reduction of oxygen to the leg muscles results in claudication pain (Bryant and Turkoski, 2000).

In order to promote the success of smoking cessation initiatives, the points listed in Box 2. should be considered.

Cholesterol - Cholesterol in the blood comes from two sources: 80% is manufactured by the liver and 20% is derived from saturated fat, excess dietary cholesterol and excess calories (Hiatt, 1998). Raised levels of serum cholesterol lead to enhanced plaque formation and stenotic disease and thus attention to a patient’s lipid profile is essential.

Plasma lipids are transported in the blood attached to lipoproteins, which modulate the efficient transfer of cholesterol and triglycerides from the gut to the liver and to peripheral tissues. Raised plasma levels of low-density lipoprotein (LDL) is associated with an increased risk of atheroma development and ischaemic events. (For people with PAD, the goal is total cholesterol <5mmol/l and LDL <3mmol/l (Belch, 1999). High density-lipoproteins (HDL) protect against an increased risk of plaque formation and CHD.

A patient’s lipid profile may be affected by smoking; smokers may have a 3% higher serum cholesterol level than non-smokers (McGill, 1988). The lipid profile can contribute to developing intermittent claudication in three ways. First, raised lipid levels can lead to early vascular damage (fatty streaks). Second, cholesterol-rich plaques can occlude and stenose vessels. Third, endothelial function is disturbed, which affects flow in the microcirculation (Belch et al, 1999)

A Cochrane systematic review examining lipid-lowering therapy in peripheral arterial disease concluded that lipid-lowering therapy may improve leg symptoms and reduce mortality (Leng et al, 1998). The nurse should:

- Be aware of the need for a lipid profile to have been undertaken within the past 12 months or a new one undertaken

- Check patient adherence to taking cholesterol-lowering medication if prescribed, emphasising that it is medication that must be taken for life and not a short course of treatment. Record any reported side-effects

- Ensure recommended follow-up of patients on statins to monitor required lowering cholesterol

- Accompany any prescription of medication with dietary advice

- Consider that information alone may not ensure healthier food choices. Intervention methods using behaviour change strategies may be useful.

Exercise - Atherosclerosis is more common in industrialised countries, where people tend to lead more sedentary lifestyles. There is general acceptance that patients can obtain significant health benefits by undertaking exercise (Ernst, 1992) and reverse some of the effects of the condition. The National Service Framework on Coronary Heart Disease (NIH, 1996) recommends that adults undertake 30 minutes of moderate-intensity activity (such as brisk walking or cycling) at least five times a week.

Patients with PAD often need a great deal of support and encouragement to undertake increased levels of activity because of the pain experienced when walking and/or exercising. Various options that can be discussed include hospital- or home-based exercise or community-led sports programmes.

The patient may be reluctant to begin exercising and any worries should be discussed. For example, some hospital classes may be held too far from home. In this case, community sports centres may offer more accessible and convenient programmes. A patient may be the main carer for another relative, necessitating a home-based programme or may simply prefer to exercise alone. An alternative plan should also be available in case exercise fails to improve walking distance.

Hypertension - Studies have shown that reducing blood pressure in patients with hypertension decreases mortality and morbidity from cardiovascular and cerebrovascular disease (Fowkes et al, 1998) Therefore the main aim of treatment should be to reduce and maintain the person’s blood pressure at optimum levels: systolic >140mmHg and diastolic >85mmHg (British Hypertension Society, 1999). In order to achieve this, contributing factors for hypertension should be assessed, including family history, smoking, high salt intake, high alcohol intake and stress. Blood pressure readings should be recorded at regular intervals to assess whether intervention is required and educational input is needed to show how stopping smoking and increasing exercise can reduce blood pressure.

Diabetes - The increased risk of atherosclerosis in coronary, cerebrovascular and limb circulation in individuals with diabetes is well known (Ekers and Hirsch, 1999). Diabetes is associated with more premature and rapid progression of PAD. Diabetic neuropathy increases the risk of the development of foot ulcers, which will be slow to heal because of reduced vascular supply. Optimal diabetic management improves the rate of lower-extremity disease progression, incidence of ischaemic events and the incidence of wound infection, gangrene and amputation (Ekers and Hirsch, 1999).

Studies have indicated that almost 40% of people with diabetes over the age of 40 have PAD (Beach et al 1988). As early diagnosis and intervention reduce morbidity and mortality from this disease, nurses should ensure that a recent fasting glucose test and urinalysis have been performed. If results are within the normal range, intervention should focus on educating the patient and family regarding the signs and symptoms of diabetes for future awareness. Any abnormalities will require referral to the diabetes care team for further assessment.

Patient education

Nurses need to take every opportunity to assess patients’ learning needs, and choose ways to educate and increase awareness of PAD and the associated risk factors. One way of motivating patients to modify their behaviour is to help them understand the nature of PAD, its prognosis and ways to control disease progression. Group education sessions may be helpful (Ekers and Hirsch, 1999). Unfortunately, personal experience suggests that large group sessions may not be appropriate for all levels of understanding and learning ability, and some people may be reluctant to ask questions when in a large group.

To reinforce information given in clinics or in wards, a variety of other teaching methods should be used, including leaflets, videos and audiotapes. Patients need basic information on the anatomy and physiology of the cardiovascular system and a simple explanation of the pathophysiology of atherosclerosis and the risk factors that contribute to the disease. Nurses need to educate patients on the key points of each risk factor and how it contributes to the disease process.

Nurses evaluating the patient’s progress at follow-up sessions should discuss their commitment, attitude, physical improvement and knowledge. If no improvement has been made the reasons for this need to be considered. If the patient chooses not to comply with advice given, he or she should be viewed not as a failure, but as someone who needs reinforcement, re-evaluation and support (Beaver, 1986).

Conclusion

PAD is a chronic disorder that first manifests as intermittent claudication. The factors which contribute to the disease are smoking, an abnormal lipid profile, a sedentary lifestyle and hypertension. Management of this patient group is shared between a number of disciplines, and nurses in primary and secondary care settings can play a significant role in assisting with lifestyle modification. Patient and family involvement is an essential part of this process.

Case study

John Green, aged 49, visited his GP following a six-month history of pain in his left thigh, which increased in severity when walking uphill. He smoked 10 cigarettes a day.

A vascular specialist opinion was sought by John’s GP. The consultant referred John to the vascular specialist nurse for full risk factor assessment and lifestyle advice.

The nurse discussed his cigarette intake at length. John described himself as ‘not a heavy smoker’ and his father ‘smoked 20 cigarettes a day and lived until he was 82’. His fasting total serum cholesterol was 7.5mmol/l, which required the prescription of a statin and dietary advice. Investigations revealed marked atheromatous disease.

John and his family expressed surprise and concern at the extent of the disease. The possibility of surgical intervention was discussed; however, John was keen to try lifestyle modification as first-line intervention.

It was at this stage that he considered the implications of smoking and asked for assistance in trying to quit. He was also advised to try to increase his exercise level and, as he worked full time, a home-based walking programme was discussed and written advice was provided.

Four months later John reported that he was now eating a healthier diet and walked daily with his wife. He had found stopping smoking very difficult. His fear of ‘needing an amputation in later life’ had initially caused his cigarette intake to increase. Praise was given at the clinic for the lifestyle changes he did achieve. Discussion centred on the effective use of nicotine replacement therapy patches and a further follow-up appointment was made.

 

 

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