Home
Back
ABI Formula:
| From: | To: |
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.
The calculator uses the ABI formula:
Where:
Explanation: The ratio compares the blood pressure in your lower legs to the blood pressure in your arms to detect potential circulation problems.
Details: ABI is crucial for diagnosing peripheral artery disease (PAD), assessing its severity, and predicting cardiovascular risk. It's recommended for patients with leg pain, non-healing wounds, or cardiovascular risk factors.
Tips: Enter the highest systolic pressure from either ankle (dorsalis pedis or posterior tibial artery) and the highest systolic pressure from either arm. Both values must be greater than 0 mmHg.
Q1: What is a normal ABI value?
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 is ABI measured clinically?
A: A blood pressure cuff is used to measure systolic pressures at the brachial artery and at both ankle arteries (dorsalis pedis and posterior tibial).
Q3: When should ABI be measured?
A: ABI should be measured when PAD is suspected (leg pain with walking, non-healing wounds) or in patients with cardiovascular risk factors.
Q4: Can ABI be falsely elevated?
A: Yes, in patients with diabetes or chronic kidney disease due to arterial calcification, which makes arteries non-compressible.
Q5: What's the difference between ABI and TBI?
A: Toe-Brachial Index (TBI) measures pressure in the toe instead of the ankle and is used when ABI is unreliable (e.g., in diabetic patients with calcified arteries).