An Ankle Brachial Index (ABI) study is a simple vascular study commonly used to diagnose Peripheral Arterial Disease (PAD). The ABI uses an ultrasound Doppler to determine the ratio of the highest systolic pressure at the arm to the systolic pressure at the ankle.
Ankle Brachial Index studies are performed using a bidirectional Dopplers such as the Huntleigh Dopplex ABIlity, DopplexABPI, Dopplex PAD.
The ABI Exam
An Ankle Brachial Index study is performed by placing the patient in a supine position and wrapping pressure cuffs around both arms and both ankles.
Using a noninvasive ultrasound vascular Doppler, pressures are taken at both arms, and the posterior tibial and dorsalis pedis arteries on each leg by inflating the pressure cuffs past the point where Doppler sounds cease, then slowly deflating the cuffs until Doppler sounds return.
Interpreting the Results of an Ankle Brachial Index (ABI)
The ABI is calculated by dividing the ankle pressure by the highest arm pressure.
When calculating the ABI ratio use the highest arm pressure to rule out subclavean steal syndrome.
Greater than 1.40 = Noncompressible 1.00 - 1.40 = Normal 0.91 - 0.99 = Borderline 0.00 - 0.90 = Abnormal