How to Calculate an Abi

Ankle-Brachial Index (ABI) Calculator

function calculateABI() { var rightAnklePressure = parseFloat(document.getElementById('rightAnklePressure').value); var leftAnklePressure = parseFloat(document.getElementById('leftAnklePressure').value); var rightArmPressure = parseFloat(document.getElementById('rightArmPressure').value); var leftArmPressure = parseFloat(document.getElementById('leftArmPressure').value); var resultDiv = document.getElementById('abiResult'); resultDiv.style.display = 'none'; // Hide previous result // Input validation if (isNaN(rightAnklePressure) || isNaN(leftAnklePressure) || isNaN(rightArmPressure) || isNaN(leftArmPressure) || rightAnklePressure <= 0 || leftAnklePressure <= 0 || rightArmPressure <= 0 || leftArmPressure 1.30) { interpretation = 'Non-compressible arteries (often indicates arterial calcification, requires further investigation).'; resultColor = '#ffc107'; // Warning yellow } else if (abi >= 1.00 && abi = 0.91 && abi <= 0.99) { interpretation = 'Borderline ABI. Suggests borderline PAD, consider re-evaluation or further testing.'; resultColor = '#ffc107'; // Warning yellow } else if (abi = 0.70) { interpretation += ' (Mild PAD)'; } else if (abi >= 0.40) { interpretation += ' (Moderate PAD)'; } else { interpretation += ' (Severe PAD)'; } } else { interpretation = 'Could not determine interpretation.'; resultColor = '#6c757d'; // Grey } resultDiv.style.backgroundColor = '#e9f7ef'; resultDiv.style.borderColor = '#d4edda'; resultDiv.style.color = '#155724'; resultDiv.innerHTML = 'Calculated ABI: ' + abi.toFixed(2) + 'Interpretation: ' + interpretation + ''; resultDiv.style.display = 'block'; }

Understanding the Ankle-Brachial Index (ABI)

The Ankle-Brachial Index (ABI) is a simple, non-invasive test used to compare the blood pressure in your ankles with the blood pressure in your arms. This comparison helps healthcare professionals assess the blood flow in your legs and detect Peripheral Artery Disease (PAD).

What is Peripheral Artery Disease (PAD)?

PAD is a common circulatory problem in which narrowed arteries reduce blood flow to your limbs, most commonly your legs. When you develop PAD, your legs don't receive enough blood flow to keep up with demand, causing symptoms such as leg pain when walking (claudication). PAD is a sign of more widespread atherosclerotic disease, which can increase your risk of heart attack and stroke.

How is ABI Measured?

The ABI test is typically performed in a doctor's office using a standard blood pressure cuff and a handheld ultrasound device (Doppler). The systolic blood pressure (the top number in a blood pressure reading) is measured in both arms and both ankles. The highest systolic pressure from each ankle is then divided by the highest systolic pressure from either arm to calculate the ABI for each leg.

Our calculator simplifies this by taking the highest ankle pressure and dividing it by the highest arm pressure to give you a single overall ABI value, which is a common clinical practice for initial screening.

Interpreting Your ABI Results

The ABI value provides crucial information about the health of your arteries:

• ABI > 1.30: Non-compressible arteries. This often indicates arterial calcification, which can occur in individuals with diabetes or chronic kidney disease. It means the arteries are stiff and cannot be compressed, making the ABI unreliable for PAD diagnosis. Further vascular testing is usually recommended.
• ABI 1.00 – 1.30: Normal. This range suggests healthy blood flow and no significant PAD.
• ABI 0.91 – 0.99: Borderline. This indicates a borderline risk of PAD. It's often recommended to repeat the test or consider additional evaluations, especially if symptoms are present.
• ABI ≤ 0.90: Abnormal. This is diagnostic of PAD. The lower the number, the more severe the PAD:
  • 0.70 – 0.90: Mild PAD
  • 0.40 – 0.69: Moderate PAD
  • < 0.40: Severe PAD

Who Should Get an ABI Test?

An ABI test is often recommended for individuals who:

• Are over 65 years old.
• Are over 50 years old with a history of diabetes or smoking.
• Have risk factors for PAD, such as high blood pressure, high cholesterol, or a family history of PAD.
• Experience symptoms of PAD, such as leg pain during exercise, numbness, or coldness in the lower legs or feet.

Disclaimer: This calculator is for informational purposes only and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always consult with a qualified healthcare provider for any health concerns or before making any decisions related to your health or treatment.