Early detection of peripheral vascular disease is a key factor in successful prevention and treatment. But which parameter or diagnostic tool is right for which situation? What does the classic ABI offer – and where are its limitations? And what role do more modern parameters like TBI or PWI™ play?
Our Know Your Indices series on social media touched on these questions – here’s a more in-depth look: compact, evidence-based, and practical.
ABI: The Classic Parameter – But Not Always Enough
The Ankle-Brachial Index (ABI) has been a standard parameter in the diagnosis of peripheral arterial disease (PAD) for decades. It’s calculated as the ratio between systolic blood pressure at the ankle and upper arm.
A normal ABI ranges from 0.9 to 1.3. Values below 0.9 suggest impaired blood flow.
However, ABI can be misleading. In patients with medial arterial calcification (MAC), diabetes mellitus, or hypertension, arteries are often stiffened – leading to falsely elevated ankle pressures and seemingly “normal” ABI results. The consequence: PAD goes undetected.
Conclusion: ABI is a solid starting point – but not sufficient for risk populations.
TBI: The More Sensitive Parameter for At-Risk Patients
The Toe-Brachial Index (TBI) operates on the same principle as ABI but is measured at the big toe. The advantage? Toe arteries are far less affected by MAC, making TBI a highly reliable indicator – even in stiffened vessels.
A TBI value below 0.7 is considered pathological. Especially in diabetic patients, TBI often provides critical clues before clinical symptoms appear.
Conclusion: Ideal for early diagnostics in patients with MAC, diabetes, or chronic kidney disease.
PWI™: An Innovative, Sensitive Index – Independent of Blood Pressure
The Pulse Wave Index (PWI™) is a modern parameter developed by SOT Medical Systems to assess vascular function. It doesn’t measure absolute pressure values but analyzes the shape of the pulse wave – particularly its rise time and amplitude.
The big advantage: PWI™ is independent of blood pressure and less affected by vascular stiffness, while still delivering highly sensitive data on post-stenotic changes.
A study by Mayr et al. (2019) confirmed that PWI™ detects relevant PAD cases that would not have been identified using ABI alone.¹
Conclusion: PWI™ is an excellent complementary parameter for early detection of vascular changes – especially in complex risk profiles.
This Is What Modern Vascular Diagnostics Looks Like
SOT Medical Systems’ Vascular Academy shares precisely this knowledge in hands-on trainings: when each index makes sense, how to combine parameters, and how to implement vascular diagnostics in a structured, efficient, and delegable workflow in both clinics and private practice.
AngE™ systems record ABI, TBI, PWI™, and more – all in a single, standardized examination process. This provides a holistic picture of vascular health – fast, validated, and reproducible.
Conclusion: Knowledge Makes the Difference
The key to better diagnostics lies in combination: no single value decides, but rather a differentiated view of multiple indices.
With the expertise from the Vascular Academy and powerful tools like the AngE™ systems, healthcare providers can take vascular diagnostics to the next level – multiparametric, efficient, delegable, and evidence-based.
📩 Want to learn more? Visit our Vascular Academy now: https://vascular-academy.com
Source:
Mayr, V., Hirschl, M., Klein‑Weigel, P., Girardi, L., & Kundi, M. (2019): A randomized cross-over trial in patients suspected of PAD on diagnostic accuracy of ankle-brachial index by Doppler-based versus four-point oscillometry based measurements. VASA – European Journal of Vascular Medicine, 48(6), 516–522. https://pubmed.ncbi.nlm.nih.gov/31274388/
