Background: Chronic leg ulcers (CLU) are very difficult to heal. Along with history and clinical examination, the ankle brachial index (ABI) is a simple, non-invasive tool used to screen peripheral arterial disease (PAD).

Objective: This study sought to evaluate the association between abnormal ABI and clinical outcomes in patients with lower limb ulcers.

Material and methods: A thorough review of the available medical literature was undertaken, exploring the full range of investigations available to screen the peripheral arterial disease. This article reviews the procedure for measuring ankle brachial pressure indices using Doppler.

Results and conclusion: ABI is a safe, non-invasive, relatively cheaper and reliable method of screening of PAD. All patients with an ABI of less than 0.8 should be referred for specialist assessment to avoid future complications.

Keywords: Chronic leg ulcers (CLU), Ankle brachial index (ABI), Peripheral arterial disease (PAD)

Lower-extremity ulceration does not only affect the patient directly but also has a great impact on the economy of the country since significant healthcare  resources are spent to treat, prevent or decrease the progression of the disease. It decreases the productivity by debilitating the person [1-3].

Foot ulcers are especially common in people who have one or more of the following health problems:

Circulatory problems: Venous/arterial (PAD)

Risk factors for PAD: Age>70 years; Age>50 years if atherosclerosis risk (Smoking, Diabetes, Hypertension, Dyslipidemia).

Peripheral neuropathy: Diabetes is the most common cause in middle aged and elderly. Abnormalities in the bones or muscles of the feet [4-7]

Abnormalities in the bones or muscles of the feet [4-7]

Clinical examination of the lower extremities must be combined with noninvasive or invasive assessment of the circulation to solidify the clinical impression [8,9].

Major international medical societies recommend calculating the ABI by dividing the highest pressure in the leg by the highest pressure in the arm. PAD severity in each leg is assessed according to the levels of ABI [13-18]:

0.91-1.30: normal;

0.70-0.90: mild occlusion;

0.40-0.69: moderate occlusion;

<0.40: severe occlusion; and

>1.30: poorly compressible vessels.

Mostly this occlusion is due to atheromatous plaques/thrombus in the lumen, until this obstruction is managed the ulcer would not heal.

The American Diabetes Association recommends measuring ABI in all diabetic patients older than 50 years or in any patient suffering from PAD symptoms or having other CV risk factors [8,9].

OBJECTIVES

The present study was undertaken:

•              To study the clinical profile of patients of lower leg and foot ulcers

•              To establish the role of ABI in prediction of vascular insufficiency

MATERIALS AND METHODS

An extensive review of the available medical literature was undertaken, exploring the full range of investigations to screen the peripheral arterial disease. The keywords Chronic leg ulcers (CLU), chronic wounds, Ankle brachial index (ABI), Peripheral arterial disease (PAD) were used as search strings, and secondary references found via bibliographic links were also retrieved. Non-English language papers were excluded from the review. A total of 35 articles reporting on technique of ABI, its availability, feasibility ,showing association between abnormal ABI and clinical outcomes in patients with lower limb ulcers were found—all were included in the review.

ABI CALCULATION

Tools needed for measuring ABI:

•              Sphygmomanometer with appropriately sized cuff(s) for both arm and ankle

•              Handheld Doppler device with vascular probe

•              Conductivity gel compatible with the Doppler device

•              Software package for recording of velocity/time waveforms of arteries.

Each ankle systolic pressure is divided by the brachial systolic pressure [16,17].

ABI Key: Abnormal: <0.9 or >1.3

REVIEW OF LITERATURE

Chronic ulceration of the lower limbs is a relatively common condition amongst adults. Chronic leg ulcers are usually associated with significant morbidity, high cost of healthcare, loss of productivity and reduced quality of life.

Peripheral artery disease is a serious health condition that increases an individual’s risk for heart attack, stroke, and leg amputation. While PAD is highly prevalent in primary care settings and is easily detected with the ABI during a routine OPD visit, the procedure is underutilized. ABI is a low cost and effective screening technique for identifying PAD in patients with cardiovascular risk factors. It should be adopted into primary care and specialty care settings. Furthermore, newly identified PAD patients could be targeted for prevention measures such as treatment with antiplatelet drugs, ACE inhibitors, and statins, decreasing their overall risk of cardiovascular events while increasing functionality and quality of life. With the combined high risk that PAD represents and the availability of effective treatment, systematic use of screening using the ABI to identify patients with asymptomatic PAD is warranted in patients with cardiovascular risk, and is critical to reduce overall morbidity and mortality. Peripheral artery disease (PAD) is characterized by symptoms of intermittent claudication or critical limb ischemia [19-32].

As per literature available these are the factors that increase risk of developing peripheral artery disease

•              Smoking

•              Diabetes

•              High blood pressure

•              Increasing age, especially after 50 years of age

•              A family history of peripheral artery disease, heart disease or stroke [28-33].

The Ankle Brachial Pressure Index (ABPI/ABI) using a hand held Doppler ultrasound and sphygmomanometer can be carried out for more accurate assessment of arterial perfusion. The results are used to determine the likelihood of arterial insufficiency and can be used to guide the management plan. The ABI is an accurate and reliable test of PAD. The sensitivity, specificity and accuracy of the ABI as a PAD diagnostic tool are well documented. Lijmer et al. [28] demonstrated a sensitivity of 79% and specificity of 96%.

An abnormal ABI may be an independent predictor of mortality, as it reflects the burden of atherosclerosis. A low ABI is not only diagnostic of PAD, but is also an effective biomarker or measure of more systemic atherosclerotic disease. Majority agree that a normal ABI is >0.9. An ABI <0.9 suggests significant narrowing of one or more blood vessels in the leg. The majority of patients with claudication have ABIs ranging from 0.3 to 0.9. Rest pain or severe occlusive disease typically occurs with an ABI<0.5. ABIs<0.2 are associated with ischemic or gangrenous extremities. Conditions such as diabetes mellitus or end stage-renal disease can give falsely elevated ABIs (1.3-1.5). The ABI test approaches 95% accuracy in detecting PAD. However, a normal ABI value does not absolutely rule out the possibility of PAD. Some patients with normal or near-normal ABI results may have symptoms suggesting PAD. If the resting ABI is normal, an exercise ABI can be conducted [9,16,18].

The evidence from the medical literature indicates that a "normal" ABPI is 0.92 or greater, a ratio below this indicating arterial disease. Cornwall et al. [24] suggested the use of Doppler ABPI measurement in the assessment of patients with leg ulceration. These suggestions were supported by Kulozik et al. [10] from Oxford.

Cornwall et al. [24] considered that an ulcer occurring in a limb with an ABPI of less than 0.9 should be considered ischaemic and that a pressure index below 0.75 had a significant impact on clinical management. This paper was the first reference linking ABPI to compression therapy.

Callam et al. [5] reported on the incidence of skin necrosis and amputation due to compression and recognized both the concept of "mixed" ulceration, i.e., venous ulceration in a limb with arterial disease, and the need for reducing the compression levels in patients with an ABPI of 0.7 or less.

According to the study conducted by O’Brien et al. [19] in Ireland the prevalence of chronic leg ulcers was 0.12% but it was 1.03% in the patients aged 70 years and over. Women were twice as likely to be affected. Venous disease accounted for 81% of ulcers and arterial disease for 16.3%, while ulceration due to diabetic neuropathy and rheumatoid vasculitis was unusual. Leg ulcers are an important source of morbidity in the ageing population. While there are few Indian studies on the epidemiology of chronic wounds, Shukla et al. [34] estimated the prevalence at 4.5 per 1000 population. The incidence of acute wounds was more than double at 10.5 per 1000 population.

Vowden [17] performed a study on Doppler assessment and ABPI. Interpretation in the management of leg ulceration and concluded that Doppler ABPI remains one of the cornerstones of the assessment process. This study aimed at reducing bandage pressure damage, but it is only one element in the overall assessment of the patient and must not be used in isolation. An ankle brachial pressure Grail of leg ulcer index (ABPI) of 0.8 is seen by some as a definitive decision-making number and it has almost become the ‘Holy assessment’.

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