Peripheral arterial disease (PAD) is a leading cause of impaired circulation and can significantly increase the risk of chronic wounds, critical limb ischemia and amputation if left undetected.
While the ankle-brachial index (ABI) is the standard screening method for PAD, it has limitations—particularly in patients with diabetes, chronic kidney disease or medial arterial calcification. In these cases, toe pressure and the toe-brachial index (TBI) provide valuable additional information about distal perfusion.
This guide explains how toe pressure and TBI are measured, why they matter and how standardized testing supports reliable vascular assessment.
What Are Toe Pressure and TBI?
Toe pressure is the systolic blood pressure measured at the toe, reflecting blood flow in the small digital arteries. Because these vessels are less affected by arterial calcification than ankle arteries, toe pressure is often more reliable in high-risk patients.
The Toe-Brachial Index (TBI) compares toe systolic pressure with brachial systolic pressure and is calculated using the following formula:
TBI = Toe Systolic Pressure / Brachial Systolic Pressure
A TBI below 0.7 is commonly considered indicative of peripheral arterial disease, although interpretation should always be made in the clinical context.
When Should Toe Pressure Be Measured?
Toe pressure measurement is particularly useful in patients where ABI may be unreliable, including those with:
- Diabetes mellitus
- Chronic kidney disease
- Non-compressible ankle arteries
- Chronic foot ulcers
- Suspected critical limb ischemia (CLI)
It is also frequently used to assess wound-healing potential and to monitor perfusion before and after revascularization procedures.
Step 1 – Prepare the Patient
Accurate measurements begin with proper patient preparation.
The patient should rest in the supine position for approximately 10 minutes before testing. The examination room should be comfortably warm to avoid vasoconstriction, and the patient should remain relaxed throughout the procedure.
Jewelry, compression garments or anything that may interfere with circulation should be removed from the feet.
Step 2 – Measure Brachial Blood Pressure
Before measuring toe pressure, systolic blood pressure should be recorded at the brachial artery.
This value serves as the reference for calculating the Toe-Brachial Index and should be measured according to standardized vascular assessment protocols.
Step 3 – Measure Toe Pressure
A small toe cuff is placed around the base of the great toe. An optical photoplethysmography (PPG) sensor is attached to detect pulse wave signals.
The cuff is inflated until blood flow temporarily stops and is then slowly deflated. The pressure at which the pulse waveform reappears corresponds to the toe systolic pressure.
Using PPG enables objective and reproducible detection of blood flow at the toe.
Step 4 – Calculate the Toe-Brachial Index
Once both values have been obtained, the TBI is calculated by dividing toe systolic pressure by brachial systolic pressure.
Interpreting the result together with the patient’s symptoms and clinical findings provides valuable insight into distal perfusion and vascular health.
Why Standardized Measurement Matters
Reliable toe pressure measurement depends on standardized testing conditions and consistent measurement techniques.
Factors such as room temperature, patient positioning and sensor placement can influence results. Following a structured protocol helps improve reproducibility and supports confident clinical decision-making.
Integrated Toe Pressure Assessment
Modern vascular diagnostic systems combine oscillometric blood pressure measurement with optical PPG technology, enabling standardized assessment of ABI, toe pressure and TBI within a single workflow.
This integrated approach supports efficient vascular screening and provides clinicians with objective information on both large-vessel circulation and distal perfusion.
👉 Learn more about integrated vascular assessment with AngE™ ABI+.
Conclusion
Toe pressure and the Toe-Brachial Index are valuable tools for assessing peripheral circulation, particularly in patients where ABI alone may not provide reliable results.
By following a standardized measurement protocol and combining toe pressure with clinical evaluation, healthcare professionals can improve the detection of peripheral arterial disease, support treatment decisions and monitor vascular interventions more effectively.
Sources:
https://www.ahajournals.org/doi/10.1161/cir.0000000000000470
