What is Ankle-Brachial Index?
The ankle-brachial index test is a quick, painless, noninvasive way to check for peripheral artery disease (PAD) of the lower extremities. Peripheral artery disease is a condition in which the arteries in the legs or arms are narrowed or blocked, mostly by atherosclerotic plaque, leading to inadequate blood supply to the effected part. They may cause symptoms of legs pain called claudication and may cause chronic ulcer of the legs or loss limb. People with peripheral artery disease has higher chance of having the same disease in other part of circulation and are at a high risk of heart attack or stroke. The ankle-brachial index test compares the blood pressure measured at the ankle (Ankle) with the blood pressure measured from the arm (Brachial).
Risk
There is no risk from this test, just like having blood pressure measurement.
Preparing for the test
No specific preparation is required for the test
During the test
Patient will be placed on supine horizontal position. There will be the standard blood pressure measurement from both arms and from arteries just distal to both ankles.
- Measure highest systolic reading in both arms
- Record first doppler sound as cuff is deflated
- Record at the radial pulse
- Use highest of the two arm pressures
- Measure systolic readings in both legs
- Cuff applied to calf, just above the malleoli
- Avoid applying over a distal bypass site (risk of bypass thrombosis)
- Use doppler Ultrasound device
- Record first doppler sound as cuff is deflated
- Record dorsalis pedis (DP) pressure (absent in 2-3% of normal patients)
- Record posterior tibial (PT) pressure
- Use highest ankle pressure (DP or PT) for each leg
- Calculate ratio of each ankle to brachial pressure
- Divide each ankle pressure by highest brachial pressure
