A Non-Invasive Physiological Study of the upper and lower extremity arteries. The ankle brachial pressure is the ratio of the blood pressure in the lower legs to the blood pressure in the arms. Compared to the arm, lower blood pressure in the leg is a symptom of blocked arteries (peripheral vascular disease). The ABI is calculated by dividing the systolic blood pressure in the arteries at the ankles and foot by the higher of the two systolic blood pressures in the arms.
A Doppler ultrasound blood flow detector, commonly called Doppler Wand or Doppler probe, is used to register the peripheral pulse while the sphygmomanometer (blood pressure cuff) is inflated over the artery until the pulse ceases, proximal to the Doppler probe.
The cuff is slowly deflated, and the corresponding sphygmomanometer pressure at the instant the pulse returns provides the systolic blood pressure reading, for the given artery. The ABI test is a popular tool for the non-invasive assessment of PVD. Studies have shown the sensitivity of the ABI is 90% with the corresponding 98% specificity for detecting hemodynamically significant (Serious) stenosis.