Toe-brachial index
A diagnostic ratio comparing toe systolic pressure to brachial systolic pressure, particularly useful in patients with non-compressible vessels.
Full Definition
The toe-brachial index (TBI) is calculated by dividing the systolic pressure at the great toe by the brachial systolic pressure. Normal values are typically above 0.7, with values below 0.7 suggesting significant peripheral arterial disease. The TBI is especially valuable in diabetic patients or those with chronic kidney disease where ankle vessels may be calcified and non-compressible, making the ankle-brachial index unreliable. Digital arteries are generally spared from medial sclerosis, providing more accurate perfusion assessment.
Usage
Usage note: Abbreviate as TBI after first use. Particularly important to document in diabetic patients.
In Context
- "Despite a normal ankle-brachial index, the toe-brachial index of 0.4 confirmed significant distal disease." — Diabetic foot assessment
- "Toe-brachial index measurement is recommended when ankle-brachial index exceeds 1.4 or appears falsely elevated." — Clinical guidelines