What is Ankle Brachial Index?
The Ankle Brachial Index is a standard and common method of physiologic assessment of vascular pathology in the lower limbs in a fast and simple manner.
Systolic pressures are measured in each of the right and left brachials, as well as at the level of the right and left ankles. Ankle Brachial Index, or ABI, is determined as the ratio between the higher brachial systolic pressure and each of the ankle pressures. Thus, a separate ABI value is obtained for the Right side and the Left sides.
Unlike ultrasound imaging modalities which provide anatomical information, ABI assessment provides a direct indication of the physiological severity of the vascular pathology. ABI testing machines are often used for fast and simple screening of the lower limbs, prior to determining if ultrasound imaging is required.
How to Measure Ankle Brachial Index
Measuring the Systolic blood pressure with an ABI machine is simple. Once a pressure cuff is wrapped around the measured site, a distal Doppler or Photoplethysmograph (PPG) waveform is obtained. The cuff is then inflated until the distal signal disappears as a result of the total occlusion. The pressure cuff is then deflated in a controlled manner, and the pressure at which the distal signal re-appears is determined as the systolic pressure.
Using Doppler to measure the distal waveform is the traditional and clinically accepted method, although PPG sensors are also used in specific conditions or locations.
Using the Falcon for ABI measurements
The Falcon is considered to be the best ankle brachial index machine as it allows very simple and fast diagnosis of ABI. Simply place 4 color-coded pressure cuffs on each of the right/left brachial and ankle sites, select the ABI protocol, and you are ready to go. The ABI test can be completed in just a couple of minutes.
The Falcon is also known as a peripheral vascular diagnosis system as it allows you to select from a wide variety of Doppler probes and PPG sensors for best outcome. All Doppler probes, PPG sensors and pressure tubes are color coded to allow optimal user interface and correlation with the dedicated software. The target inflation pressure, as well as the deflate rate and various other parameters can be customized by the user for optimal measurements.
Numerous other features and options of the Falcon system, such as automatic cuff inflation once a signal is identified, or simultaneous measurements, display of contralateral results, and many more options, are designed to simplify the use of the Falcon ABI physiologic system in a fast and efficient way.
Once the distal Doppler or PPG waveform reappears during the deflation phase of the pressure cuff, the measurement can be stopped, and the Falcon places a cursor to mark a potential systolic pressure. The user may move the cursor to a different location, and the systolic pressure is changed accordingly. R/L ABI are calculated automatically by the Falcon and presented clearly on the screen and in the report layout.
Expected Results of ABI Test
|ABI ≥ 1.4||Non compressible arteries|
|1 ≤ ABI < 1.4||Normal|
|0.9 ≤ ABI < 1||Borderline|
|ABI ≤ 0.9||Abnormal|
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