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) in the legs. It compares the blood pressure in the ankle with the blood pressure in the arm to determine how well blood is flowing in your limbs.

2. How Is ABI Calculated?

The ABI is calculated using the following formula:

Where:

• Ankle Pressure — The highest systolic blood pressure measured at either the dorsalis pedis or posterior tibial artery
• Brachial Pressure — The highest systolic blood pressure measured in either arm

Explanation: The ratio compares the blood pressure in your lower legs to the blood pressure in your arms. A lower ratio suggests possible peripheral artery disease.

3. Importance of ABI Measurement

Details: ABI is a valuable screening tool for peripheral artery disease. It helps identify individuals at risk for cardiovascular events and can guide treatment decisions for PAD.

4. Using the Calculator

Tips: Enter the highest systolic pressure from either ankle and the highest systolic pressure from either arm. Both values must be valid (greater than 0 mmHg).

5. Frequently Asked Questions (FAQ)

Q1: What is a normal ABI value?
A: A normal ABI ranges from 0.9 to 1.3. Values below 0.9 suggest PAD, while values above 1.3 may indicate non-compressible vessels.

Q2: How should ABI measurements be taken?
A: The patient should rest for 5-10 minutes before measurement. Blood pressure cuffs are placed on both arms and ankles, with Doppler used to detect pulses.

Q3: What does an ABI less than 0.9 mean?
A: An ABI < 0.9 suggests PAD, with lower values indicating more severe disease. Values < 0.5 suggest critical limb ischemia.

Q4: Why might ABI be greater than 1.3?
A: ABI > 1.3 suggests non-compressible vessels, often due to arterial calcification (common in diabetes or renal failure).

Q5: How often should ABI be measured?
A: For PAD screening, every 5 years in high-risk patients. More frequently if known PAD or symptoms develop.