Ankle Brachial Pressure Index (ABPI), also known as Ankle Brachial Index (ABI), is a blood pressure measurement to assess the circulation in lower extremities.
The normal range for the ankle-brachial index is between 0.90 and 1.30. An index under 0.90 means that blood is having a hard time getting to the legs and feet: 0.41 to 0.90 indicates mild to moderate peripheral artery disease; 0.40 and lower indicates severe disease.
An ankle-brachial index over 1.30 is usually a sign of stiff, calcium-encrusted arteries. These often occur in people with diabetes or chronic kidney disease. In such cases, blood pressure should be measured at the toe, where arteries are less likely to be rigid.