Lower limb assessment

Risk factors

Venous insufficiency includes a broad spectrum of venous complaints which range from telangiectasias or ‘spider veins’ (named for their spider web appearance) and varicose veins, to chronic venous ulcers and deep vein thrombosis (DVT) (Ballard and Bergan, 2000). The majority of the research indicates that women are more likely than men to have varicose veins (Ballard and Bergan, 2000). The risk factors for venous insufficiency include increasing age, in both men and women, genetics, occupation (prolonged standing or heavy lifting), pregnancy, and diet; some evidence suggests that a western diet of reduced fibre and refined foods leads to constipation and intra-abdominal pressure from straining is transmitted to the veins in the legs (Ballard and Bergan, 2000). Other risk factors are obesity, smoking, reduced mobility and haematological factors (Woods, 2019). Increased venous pressure over time leads to a chronic inflammatory response, which can cause the breakdown of tissue resulting in venous leg ulceration (Wounds UK, 2016).

Assessment

Early assessment, diagnosis and intervention is essential to reduce the burden of CVI and improve quality of life. The CEAP (Clinical-Etiological-Anatomical-Pathophysiological) classification tool is a standardised method used in the management of CVI (Eklöf et al, 2004) (Table 1). Originally established as a tool to assess for recurrent varicose veins, it identifies early signs of venous disease. The tool was modified in 2004 to include chronic venous disorders. CEAP is a descriptive classification and can be used in conjunction with other venous severity scoring tools.

Ankle–brachial pressure index

Following full visual assessment nurses should consider a level one assessment of the venous system with a handheld continuous-wave Doppler for an ankle-brachial pressure index (ABPI) assessment (Ballard and Bergan, 2000). The ABPI assessment is not intended for diagnosis of venous disease but rather excludes significant arterial disease by comparing systolic blood pressure between the arm and ankle (Wounds UK, 2019).

This procedure must be carried out by a competent clinician who understands and is able to interpret results to confirm safe practice. A list of contraindications to Doppler assessment is shown in Box 1.

Contraindications to Doppler assessment

The ABPI ratio is usually above 1. A value below 0.92 is considered abnormal and an indication of peripheral arterial disease (Vowden and Vowden, 2018). Early intervention with class I or class II compression garments when C1 or C2 venous disease has been confirmed significantly reduces further complications associated with venous disease. Patients who are managed with compression should have regular vascular assessments to ensure their arterial status has not worsened (Wounds UK, 2016). Patients with a ABPI of less than 0.5 are not suitable for compression and should be referred to a vascular surgeon. Patients with an ABPI of 0.5–0.8 may be suitable for reduced compression but this must only be applied by competent nurses who have received the correct education and training.

Before carrying out an assessment it is essential to correctly assemble all the necessary equipment.

Procedure for ABPI assessment

Confirm the patient's identity, explain and discuss the full procedure and obtain consent

Wash hands and put on apron and gloves

Help the patient to lie down. To record the best resting ABPI the patient should be asked to remain as still as possible for 30 minutes. This is a crucial part of the assessment and should not be rushed (Moffatt et al, 2007; Whayman, 2014)

Ensure the patient is lying as flat as possible to reduce hydrostatic pressure inaccuracies, which can lead to falsely high ABPI readings. If the patient is unable to lie flat, try to bring their legs as close to heart level as possible. Document the position of the patient to ensure consistency for future readings

Observe the lower limb for any previous leg ulcer scars and ask the patient about their venous history. Check whether the patient has had any surgery for varicose veins involving ligation (tying off) and stripping (removal), or endothermal ablation (energy from high-frequency waves or lasers to seal the affected veins) (NICE, 2013)

Observe the lower limb for signs of telangiectasias (spider veins)—these are commonly found on the back of the leg. Spider veins are small superficial veins or arterioles. Spider veins measure less than 1.0 mm in diameter and occur mainly in the lower extremities. Reticular veins are located in the subcutaneous tissue, they measure less than 3 mm in diameter and are often tortuous (twisted) and widened (Nakano et al, 2017)

Check for visible, palpable varicose veins larger than 3 mm. These are the most significant indicator of venous insufficiency. It is important to explain to patients that once chronic venous disease begins, the delivery of nutrients and oxygen to the skin is being compromised and complications can easily develop

Assess lower limb for swelling, oedema and lymphorrhea (lymphatic leak). Pitting oedema is the result of applied pressure over oedematous subcutaneous tissue. This results in a depressed area caused by displaced interstitial fluid and typically worsens throughout the day (Brodovicz et al, 2009). This can be assessed by firmly pressing your thumb onto the skin for at least 2 seconds on each limb

Observe the limb for any skin changes:

Lipodermatosclerosis: defined as areas of painful, tight skin with hardened subcutaneous tissue just above the ankle (NICE, 2019). This is due to infiltration of fibrin and inflammation and results in an altered limb shape resembling an inverted champagne bottle

Hyperpigmentation: identified by a reddish-brown discolouration of the skin due to the deposition of haemosiderin

Varicose eczema: itchy, red, flaky and scaly skin, which may blister with surface crusts (NICE, 2019)

Atrophie blanche: white, star-shaped scarred areas with surrounding pigmentation (NICE, 2019)

Examine the foot, locating the dorsalis pedis, anterior tibial, peroneal and posterior tibial pulses. Palpate foot pulses. Reduced or absent pulses may indicate peripheral arterial disease (Londero et al, 2016). It is important to note that 10% of the population have an absent dorsalis pedis (Figure 2)

Measure brachial systolic blood pressure in both arms (unless contraindicated). This is the fundamental principle underpinning ABPI calculation and supports identification and management of a number of medical conditions (Vowden and Vowden, 2018)

Place an appropriately sized cuff around the upper arm. It is essential to use the appropriate cuff size for the patient. A cuff that is too small can result in an overestimation of pressure, a cuff that is too big can lead to an underestimation of pressure (Vowden and Vowden, 2018). Try to avoid repeatedly inflating the cuff before it has fully deflated as this can alter pressures (Whayman, 2014)

Locate the brachial pulse and apply ultrasound gel

Hold the Doppler probe at 45 degrees to the arm in the direction of the heart. Move the probe around until a pulse is located. If a continual ‘whoosh’ sound is heard, this is a vein and should not be used to calculate the ABPI (Whayman, 2014)

Slowly inflate the cuff until the signal is no longer heard. Slowly deflate the cuff and record the pressure when the signal returns. Avoid rapidly deflating the cuff. This may result in the highest pressure being missed (Vowden and Vowden, 2018)

Repeat this procedure on the other arm

Place an appropriately sized cuff around the ankle just above the malleoli. If required and for infection control purposes, cover leg ulcers or other wounds with clean film before the application of the blood pressure cuff

Apply ultrasound gel to the foot pulses and continue as for brachial pressure, recording in the same way. A minimum of two pulses should be used for each leg to calculate an ABPI. The anterior tibial and dorsalis pedis should not both be used in the same assessment as they form part of the same artery

Listen to the Doppler sounds to assess the level of arterial disease. A triphasic sound, where three beats are heard, is the sound of a healthy artery. Biphasic sound is where two beats are heard, often in older patients who have altered physiology due to the normal ageing process. Monophasic or a single beat heard indicates that the vessel is diseased. It is important that nurses have good knowledge of the anatomy of the four foot pulses and arterial sounds to comprehend the state of the vessel (Whayman, 2014)

Repeat for the other leg

To calculate an ABPI the highest reading on the right foot should be divided by the highest systolic brachial. This should be repeated with the left foot, taking the highest reading on the left foot and dividing by the highest systolic brachial reading. This gives ABPI for the arterial vessels in both legs (Staines, 2018) (Box 2).

Refer to local policy for interpretation of the ABPI values (NICE, 2019)

Document the assessment in the patients' records

Give the patient lifestyle advice to relieve symptoms of CVI and reduce risk factors. This should include advice around weight (obesity predisposes individuals to venous stasis—slow blood flow in the veins—which can trigger DVT and CVI) (Willenberg et al, 2010). They should be advised to engage in moderate physical activity including calf muscle pump exercises (Padberg et al, 2004; NICE, 2013) and avoid activities that require sitting or standing for prolonged periods of time (NICE, 2013). Advise the patient to elevate legs when sitting to improve blood flow back to the heart. If compression is indicated, establish safe practice.

Automated devices can simplify and speed up accurate recording of ABPI and facilitate early detection of peripheral arterial disease compared with the traditional Doppler testing. These machines can be used as second-line assessment if the patient requires extensive assessment or for reassessment (Wounds UK, 2019).

Box 2.

Calculating ABPI

ABPI (Right) = P(R)/P(B)

ABPI (Left) = P(L)/P(B)

P(R) = Highest systolic pressure obtained from the vessels in the right ankle

P(L) = Highest systolic pressure obtained from the vessels in the left ankle

P(B) = Highest of the two brachial pressures

Source: Vowden and Vowden, 2018

Summary

In summary, the most common cause of CVI is venous reflux. Early assessment, diagnosis and intervention can reduce complications of CVI and prevent further deterioration, which can lead to leg ulceration. Nurses should be competent in recognising early signs of venous disease and provide patients with information to relieve symptoms and reduce risk factors. ABPI assessment is used to ensure safe practising of compression, or it can confirm peripheral arterial disease, which can trigger appropriate referrals and treatment.

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