AnkleBrachial Index Test The AnkleBrachial Index one of

Ankle-Brachial Index Test

The Ankle-Brachial Index • one of the most useful objective parameters to assess lower extremity arterial perfusion is the Ankle-Brachial Index (ABI) • Compares the systolic blood pressure of the ankle (dorsalis pedis) to that of the arm (Brachial) • Done to measure blood pressure at the ankle and in the arm while the patient is at rest

The Ankle-Brachial Index • Why is this done? – This test is done to screen for peripheral vascular disease – Can be used to determine increasing pressure in extremities (compartment syndrome) • ABI – used to predict the severity of peripheral vascular disease that may be present – a decrease in the ABI result with exercise is a sensitive indicator that significant PVD exists – if both ankle pressure and brachial pressure are relatively the same, one can assume there is little or no peripheral vascular disease (occlusion).

Interpretation • Ankle-Brachial ratio >0. 9: – Normal • Ankle-Brachial ratio 0. 75 to 0. 9: – Mild disease, • Ankle-Brachial ratio <0. 5 to 0. 75: – moderate disease, some Claudication

Interpretation • 0. 9 to 1 ABI Normal • 0. 75 to 0. 9 ABI Mild disease • 0. 5 to 0. 75 ABI Moderate disease • 0. 35 to 0. 5 ABI Severe disease • 0. 25 to 0. 35 ABI resting ischemic pain • less than 0. 25 ABI Gangrenous extremity, consistent with nonhealing, severe limb threatening ischemia

False Negative Test • Vessels in diabetics – This is NOT a reliable test for those with diabetes(noncompressible vessels) – arterial calcification causes false readings (high) • Unproper size cuff (large leg, standard cuff = erroneously high pressure**) – ** 11/2 times-greater-than-limb diameter rule

The Ankle-Brachial Index • Calculation – by dividing the blood pressure at the ankle by the pressure in the arm – ABI = Ankle pressure – Brachial pressure

The Ankle-Brachial Index • Procedure – patient placed in supine position – brachial and ankle systolic pressures are obtained – take bilateral upper extremity pressure readings – the higher of the systolic pressures is used to calculate the ABI

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 – record first doppler sound as cuff is deflated – use doppler ultrasound device • record dorsalis pedis pressure • record posterior tibial pressure • use highest ankle pressure (DP or PT) for each leg

Calculate ratio of each ankle to brachial pressure • Divide each ankle by highest brachial pressure