Description

The ABI (Ankle-Brachial-Index) is an evaluation criterion of the perfusion in the extremities based on the pressures in the arteries. It is mainly used to determine blood flow disorders related to peripheral arterial occlusive disease (PAOD).

Historically, the systolic blood pressures are taken manually on each extremity individually by applying a pressure cuff and a vascular Doppler. The pressure is then slowly released using a handheld manometer.

The modern approach is the oscillometric method, in which pressures are recorded by applying four simultaneous measurement cuffs on upper arms and ankles using an automated system. This approach is operator independent, time efficient and allows a direct side-by-side comparison of the pulse waves (where a time difference can be an indicator for an arterial occlusion). Additionally, the pulse wave shape is recorded and can be further examined.

For the oscillometric ABI measurement (oABI), the perfusion of the vessels is recorded using pressure cuffs on ankles and upper arms (alternatively on wrists), which register the oscillations of all underlying vessels in each extremity. Those collective pressure signals of the arteries and collaterals are used for the calculation of the oABI.

Measurement Principle