Ankle Brachial Index

Other Names

Ankle-Brachial Index measurement

Ankle brachial index (ABI)

Measurement of Ankle Brachial Index

• ABI
• Ankle–Brachial Pressure Index
• Ankle–Arm Index
• Ankle–Brachial Pressure Ratio
• Ankle Brachial Pressure Index (ABPI)
• Ankle–Brachial Ratio

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Purpose

• Screen for, diagnose, and assess the severity of peripheral arterial disease (PAD)
• Done by comparing systolic blood pressure at the ankle to that of the arm
• First described in the 1950s by physician Travis Winsor

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Description

Setup

• Patient Position: Lying supine for at least 5–10 minutes to stabilize blood pressures
• Equipment: Blood pressure cuff and Doppler ultrasound probe
• Measurement Sites
  • Upper: Brachial artery (both arms)
  • Lower: Dorsalis pedis artery (both feet), Posterior tibial artery (both feet)

Procedure

• Place a cuff around the arm and measure systolic pressure using a Doppler probe
• Repeat for the opposite arm
• Place cuff around the ankle and measure systolic pressure at dorsalis pedis and posterior tibial arteries

Calculation

• ABI = Higher ankle systolic pressure ÷ Higher brachial systolic pressure

Interpretation

• 1.0–1.3: Normal
• 0.91–0.99: Borderline
• 0.41–0.90: Mild to moderate PAD
• ≤0.40: Severe PAD
• >1.3: Non-compressible arteries (may indicate calcification)

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Pathology

• Peripheral Vascular Disease
• Peripheral Arterial Disease

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Evidence

Peripheral Arterial Disease

• Xu et al
  • Sensitivity: 15-79%
  • Specificity: 83-99%

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See Also

• Physical Exam Main
• Vascular Anatomy
• Vascular Disease Main

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