Ankle Brachial Pressure Index
What is an ankle brachial pressure index (ABPI)?
Ankle brachial pressure index (ABPI) is a non-invasive method of quantifying the severity of arterial disease in the legs. It is measured by inflating a blood pressure cuff placed around your calf, whilst simultaneously listening to the quality of the flow signals from the foot arteries with a hand held Doppler device. The maximum pressure at which the signal can still be heard is termed the ankle systolic pressure. This is then divided by the brachial (arm) systolic pressure to create a ratio, with normal being in the range 0.9-1.3. A ratio less than 0.7 is diagnostic for the presence of peripheral arterial disease.
When would an ankle brachial pressure index be performed?
For patients presenting with leg ulceration or leg pain, ABPI measurement is a rapid screening tool for detecting the presence of underlying arterial disease. With this additional information your surgeon will be better placed to decide on the most appropriate next investigation and/or treatment.
How accurate is the ankle brachial pressure index?
There are certain clinical conditions, such as diabetes, that may render an ABPI measurement inaccurate and falsely reassuring. For these conditions we would recommend combining ABPI measurement with an alternative method of perfusion assessment, like a duplex Doppler ultrasound scan to ensure subtle underlying disease is not overlooked.