Ankle Brachial Index

1. The ankle-brachial index (ABI) is a simple, reliable means for diagnosing peripheral arterial disease (PAD). The ABI can predict how severe an individual's atherosclerosis is and the risk of future leg problems (such as developing future leg rest pain, poor healing of foot wounds). It can also predict the risk of future problems from atherosclerosis in other parts of the body (such as heart attack and stroke). Lower ABI values are associated with a higher risk.

2. You will be asked to lie on your back while standard blood pressure cuffs are placed around your ankles and arms. These cuffs will be inflated briefly above your normal systolic blood pressure. Once the cuffs are deflated, blood pressure measurements are taken using the Doppler instrument. The arm and ankle systolic blood pressure measurements are recorded. Then the ankle systolic pressures are divided by the highest arm pressure to establish an ABI measurement for each leg. The ABI range that is generally considered normal is .90 to 1.2.

3. Although the ABI is extremely reliable, this test may not be accurate in all patients. Some patients with long-standing diabetes, kidney disease, or some elderly patients, may have rigid blood vessels. These may be difficult to compress with the blood pressure cuff and, in these patients, the ABI reading may not be accurate.