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

The Ankle-Brachial Index (ABI) is a simple, non-invasive test that compares the blood pressure in the upper and lower limbs to assess peripheral arterial disease (PAD). It's calculated by dividing the systolic blood pressure measured at the ankle by the systolic blood pressure measured at the arm.

2. How Does the Calculator Work?

The calculator uses the ABI formula:

Where:

• Ankle Pressure — Highest systolic pressure from either ankle (mmHg)
• Brachial Pressure — Highest systolic pressure from either arm (mmHg)

Interpretation:

• ABI > 1.3: Non-compressible vessels (possible calcification)
• 0.9-1.3: Normal
• 0.7-0.9: Mild arterial disease
• 0.4-0.7: Moderate arterial disease
• < 0.4: Severe arterial disease

3. Importance of ABI Measurement

Details: ABI is a reliable screening tool for peripheral arterial disease (PAD). It helps identify patients at risk for cardiovascular events and guides treatment decisions.

4. Using the Calculator

Tips: Enter the highest systolic pressure from either ankle and the highest systolic pressure from either arm (both in mmHg). The calculator will determine the ABI and provide an interpretation.

5. Frequently Asked Questions (FAQ)

Q1: How should blood pressures be measured for ABI?
A: Use a Doppler ultrasound device to measure systolic pressures in both arms and both ankles (dorsalis pedis and posterior tibial arteries).

Q2: What if my ABI is >1.3?
A: Values >1.3 suggest non-compressible arteries, often due to calcification in diabetic patients or those with chronic kidney disease.

Q3: How often should ABI be measured?
A: For PAD patients, annually; for high-risk patients without PAD, every 2-5 years depending on risk factors.

Q4: Can ABI be used during pregnancy?
A: ABI interpretation may be less reliable during pregnancy due to hemodynamic changes.

Q5: What are the limitations of ABI?
A: ABI may be less accurate in patients with non-compressible vessels, acute limb ischemia, or severe arterial calcification.