1. What is the Ankle-Brachial Index (ABI)?

The Ankle-Brachial Index (ABI) is a simple, non-invasive test used to assess peripheral arterial disease (PAD). It compares the blood pressure in your ankle with the blood pressure in your arm to evaluate circulation in your limbs.

2. How Does the Calculator Work?

The calculator uses the ABI formula:

Where:

• Ankle Pressure — Highest systolic pressure from either dorsalis pedis or posterior tibial arteries (mmHg)
• Brachial Pressure — Highest systolic pressure from either arm (mmHg)

Interpretation:

• >1.4: Abnormal (possibly non-compressible vessels)
• 1.0-1.4: Normal
• 0.9-1.0: Borderline
• 0.5-0.9: Mild to moderate PAD
• <0.5: Severe PAD

3. Importance of ABI Calculation

Details: ABI is crucial for diagnosing peripheral arterial disease, assessing its severity, and predicting cardiovascular risk. It's recommended for patients with leg pain, non-healing wounds, or cardiovascular risk factors.

4. Using the Calculator

Tips:

• Measure blood pressure in both arms and both ankles
• Use the higher of the two brachial pressures
• Use the higher of the two ankle pressures for each leg
• Calculate ABI separately for each leg
• Patient should rest for 5-10 minutes before measurement

5. Frequently Asked Questions (FAQ)

Q1: What is a normal ABI range?
A: Normal ABI ranges from 1.0 to 1.4. Values below 0.9 suggest PAD, while values above 1.4 may indicate non-compressible vessels.

Q2: How often should ABI be measured?
A: For patients with risk factors, every 1-2 years. For diagnosed PAD, frequency depends on symptoms and treatment.

Q3: Can ABI be falsely elevated?
A: Yes, in patients with diabetes or chronic kidney disease due to arterial calcification.

Q4: What if the ABI is different between legs?
A: Significant differences (>0.15) may indicate unilateral arterial disease.

Q5: Are there alternatives to ABI?
A: For patients with non-compressible vessels, toe-brachial index (TBI) or pulse volume recordings may be used.