Ankle Brachial Index (ABI)

An ankle brachial index (ABI) is a simple, non-invasive test used to assess the blood pressure in the lower extremities. It compares the blood pressure measurements taken at the ankle with those taken at the arm (brachial artery) to determine the ratio between the two.

During the ABI test, blood pressure cuffs are placed on both arms and ankles. The systolic blood pressure (the highest pressure when the heart beats) is measured in both locations using a Doppler ultrasound device. The ankle pressure is divided by the brachial (arm) pressure to calculate the ABI.

 

A normal ABI value typically falls between 0.90 and 1. An ABI below 0.90 indicates peripheral artery disease (PAD), a condition characterised by narrowed or blocked arteries in the legs. Values above 1.2 may suggest calcification or stiffening of the arteries.

 

The ABI test is primarily used to diagnose PAD, evaluate its severity, and assess the risk of complications such as ulcers, infections, or poor wound healing in individuals with lower extremity arterial disease. It is a useful screening tool to identify patients who may require further evaluation or intervention to improve blood flow in their legs.

 

It's important to note that tan ABI is just one component of the diagnostic process and additional tests or examinations may be needed to confirm a diagnosis or determine the best course of treatment for peripheral artery disease.

This test usually takes between 15-20 minutes to complete.

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An Ankle Brachial Index Pressure Study (ABI) assesses the ratio between the blood pressure in your arm compared to the arteries in your feet at rest. A hand held doppler with a pencil probe will be used for this study. We will require you to remove your shoes and socks, as well as your jumper. We will ask you to lie down on the examination bed. We will place a blood pressure cuff around your lower calf and apply gel to the top of your foot and under your ankle. We will use the hand-held Doppler to find the arteries and then inflate/deflate the blood pressure cuff to determine the blood pressure. We will repeat this process on your arm as well.

An ankle brachial index test is a non-invasive and quantitative assessment of blood flow in the lower extremities and is a valuable tool in diagnosing, managing, and monitoring peripheral artery disease. The ankle-brachial index (ABI) is done for several reasons, primarily to assess the blood flow and circulation in the lower extremities.

 

Diagnosing Peripheral Artery Disease (PAD)

An ankle brachial index is a commonly used test to diagnose peripheral arterial disease, a condition characterised by narrowed or blocked arteries in the legs. A low ABI value indicates reduced blood flow to the lower extremities, suggesting the presence of peripheral arterial disease.

 

Evaluating the Severity of PAD

An ankle brachial index can help determine the extent or severity of peripheral arterial disease. The lower the ABI value, the more severely the blood flow has been compromised.

 

Assessing the Risk of Complications

Individuals with peripheral arterial disease are at an increased risk of complications such as non-healing ulcers, infections, or tissue damage in the legs and feet. An ABI can help assess the risk of these complications by providing information about the adequacy of blood supply to the lower extremities.

 

Monitoring Disease Progression

The ABI can be used over time to monitor the progression of PAD or the effectiveness of treatment interventions. Regular ABI measurements can help determine if the condition is stable, improving, or worsening.

 

Guiding Treatment Decisions

ABI results can assist healthcare providers in determining the appropriate treatment approach for individuals with PAD. It helps identify patients who may benefit from interventions such as lifestyle modifications, medications, angioplasty, stenting, or bypass surgery to improve blood flow in the legs.