Performing Ankle Brachial Index (ABI) Measurement

Sensitive and Specific + Inexpensive Test for Diagnosing PAD [In Patients with Clinical History and Exam Suggestive of Chronic Peripheral Arterial Disease]

Measuring Resting ABI Accurately:

 • Patient should be resting >5-10 Minutes

 • Use Appropriate Cuff Size Place Cuff - 2cm Above (width be at least > 40% circumference of limb)

 • Place cuff ~2cm above medial malleolus

 • Recommend CW Doppler to Measure SBP 

 • Inflate Cuff Slowly to ~20 mmHg above loss of flow signal

 • Slowly Deflate Until Signal Returns (Repeat Measurement in Other Vessel in Same Limb)

 • Same Sequence Each Time (Right Brachial → Right PT/DP → Left PT/DP → Left Brachial)

ABI = Highest Pressure in Lower Limb (DP or PT) / Highest Pressure in Both Arms

ABI ≤ 0.9:

 • In patients with s/sx of PAD, diagnostic (Se of 95%, Sp 100%) for occlusive lesion >50%

ABI: 0.91-0.99:

 • Considered "Borderline" and further diagnostic testing suggested (e.g., Exercise ABI)

ABI: 1.0-1.4:

 • Considered normal. However, if s/sx highly suggestive of PAD, further testing recommended

ABI > 1.4:

 • Indicative of calcified Non-Compressible Vessels. Toe-Brachial Index (TBI) can be used



- Karan Desai MD @karanpdesai via CardioNerds @cardionerds



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