toe-brachial index
Ratio of toe to arm blood pressure used to assess arterial circulation in patients with diabetes or calcified vessels.
Full Definition
The toe-brachial index (TBI) is a diagnostic measurement calculated as the ratio of systolic blood pressure in the great toe to the highest brachial systolic pressure, providing assessment of arterial circulation when standard ankle-brachial index measurements may be unreliable. This test is particularly valuable in patients with diabetes mellitus or chronic kidney disease, where vessel calcification can produce falsely elevated ankle pressures. In vascular medicine documentation, TBI values below 0.7 typically indicate significant arterial disease, and accurate reporting of both numerator and denominator pressures is essential for clinical interpretation.
Usage
Usage note: Essential when ankle-brachial index is unreliable due to vessel calcification; always report as decimal ratio.
In Context
- "The toe-brachial index of 0.5 confirmed significant arterial disease despite normal ankle-brachial measurements." — Vascular laboratory report
- "TBI measurement was performed using photoplethysmography due to the patient's heavily calcified vessels." — Diagnostic procedure documentation