Texas Innovative Vascular Care

ABI-TBI Study

The Ankle Brachial Index (ABI) and Toe Brachial Index (TBI) are non-invasive tests used to assess blood flow in the lower extremities and help diagnose peripheral artery disease (PAD). Both tests compare blood pressure measurements in different parts of the body to evaluate arterial health and detect blockages or narrowing in the arteries.

ANKLE BRACHIAL INDEX (ABI)

How ABI Works

Blood Pressure Measurement

Blood pressure cuffs are placed on the arms and ankles.

Doppler Ultrasound

A Doppler ultrasound device is used to measure systolic blood pressure at the brachial artery (in the arm) and at the ankle.

Calculation

The ABI is calculated by dividing the systolic blood pressure at the ankle by the systolic blood pressure at the arm.

ABI Interpretation

Normal ABI: 1.0 to 1.4

(indicating no significant blockage)

Borderline ABI: 0.91 to 0.99

(suggesting possible mild PAD)

Abnormal ABI: Less than 0.90

(indicating PAD), or greater than 1.4

Severely Abnormal ABI: Less than 0.40

(indicating severe PAD)

Toe Brachial Index (TBI)

How TBI Works

Blood Pressure Measurement

A smaller blood pressure cuff is placed on the toe, and another on the arm.

Doppler Ultrasound

These devices measure systolic blood pressure at the toe and at the arm.

Calculation

The TBI is calculated by dividing the systolic blood pressure at the toe by the systolic blood pressure at the arm.

TBI Interpretation

Normal TBI: Greater than or equal to 0.7

(indicating no significant blockage)

Abnormal TBI: Less than 0.7

(indicating PAD)

Applications Of ABI And TBI

Assessment of Severity

ABI and TBI help determine the severity of arterial blockages.

Diagnosis of PAD

Both tests are commonly used to diagnose peripheral artery disease, especially in patients with symptoms like leg pain, claudication, or non-healing wounds.

Guiding Treatment Decisions

Results from ABI and TBI tests guide treatment plans, including lifestyle changes, medications, and potential surgical interventions.

Monitoring Disease Progression

These tests can be repeated over time to monitor the progression of PAD.

Benefits Of ABI And TBI

Non-Invasive: Both tests are painless and do not require needles or incisions.
Quick and Simple: They can be performed in a short amount of time, often in a doctor's office or vascular lab.
Early Detection: These tests help in the early detection and management of PAD, improving patient outcomes.

Drawbacks Of ABI And TBI

Calcified arteries may give erroneously normal results which can be further evaluated with doppler ultrasound.
ABI is typically preferred for initial screening of PAD, while TBI is useful in cases where ABI results may be unreliable, such as in patients with diabetes or calcified arteries.
Click Here for Additional Information

ABI-TBI Exa