Home / Applications / Clinical exams / Toe pressure and TBI

Toe pressure and TBI

Toe pressure and TBI are noninvasive macrocirculation measurements for evaluating blood perfusion in the toes, providing critical insight into vascular health. Toe pressure measurements are useful in wound healing, detecting and managing peripheral artery disease (PAD) and chronic limb-threatening ischemia (CLTI) — especially when ankle pressure may be unreliable due to noncompressible arteries.

toe pressure

Toe pressure versus TBI

Toe pressure is the absolute measurement of local blood perfusion in the toes and its thresholds are used in a variety of clinical assessments. TBI is the ratio of toe pressure to brachial (arm) pressure. By accounting for variations in systemic blood pressure, TBI normalizes toe pressure which helps clinicians interpret low toe perfusion values. 

Clinical significance of toe pressure

The small arteries in the toes are less likely to be calcified than larger vessels like those in the ankle [1]. This makes toe pressure and TBI measurements useful when diagnosing patients with diabetes or chronic kidney disease — where arterial calcification can render ankle-brachial index (ABI) measurements inaccurate.

Toe pressure provides insights into:

  • Peripheral blood perfusion — helps evaluate the severity of arterial disease.
  • Wound healing potential — indicates whether blood perfusion is sufficient to support tissue repair.
  • Revascularization outcomes — assess change in circulation after surgical or endovascular interventions.

Low toe pressures (<30 mmHg) are strongly associated with critical ischemia [2]. Early detection through toe pressure measurement helps guide timely interventions, reducing the risk of complications.

PAD and wound-healing reference values[2]

Diagnosis
ABI 0.9 – 1.3
} PAD is less likely
TBI ≥ 0.7
Prognosis
AP (mmHg) < 50 impaired healing
ABI < 0.5 impaired healing
TP (mmHg) ≥ 30 healing probability increases up to 30%
Treatment
Ischemia (a) Severe isc. (b)
AP (mmHg) < 100 < 50
ABI < 0.4
TP (mmHg) < 60 < 30

According to [2], people with diabetes should undergo toe pressure exams. If toe pressure and ABI do not correlate, toe pressure is the primary determinant of ischemia grade. If arterial calcification precludes reliable ABI or toe pressure, ischemia should be documented by Tcp02, SPP, or PVR.

Accurate and repeatable toe pressures with PeriFlux 6000

PeriFlux 6000 solutions are designed for clinicians to carry out pressure measurements easily. Attach the laser Doppler probe to the toe with double-sided tape, wrap a toe cuff around the toe, and start occlusion. 

Our thermostatic laser Doppler probes promote measurement reliability in cases of low toe pressure caused by vasoconstriction and is a more sensitive technology than photoplethysmography (PPG).

References

  1. Mills, J. L., Sr, Conte, M. S., Armstrong, D. G., Pomposelli, F. B., Schanzer, A., Sidawy, A. N., Andros, G., & Society for Vascular Surgery Lower Extremity Guidelines Committee (2014). The Society for Vascular Surgery Lower Extremity Threatened Limb Classification System: risk stratification based on wound, ischemia, and foot infection (WIfI). Journal of vascular surgery, 59(1), 220–34.e342. https://doi.org/10.1016/j.jvs.2013.08.003
  2. International Working Group on the Diabetic Foot (IWGDF). Guidelines on the prevention and management of diabetic foot disease (2023 update). https://iwgdfguidelines.org