1. TBI or not TBI with Diabetic patients The Question for Vascular labs
Liz Lawrence, RDMS, RDCS, RVT

2. TBI or not TBI: that is the question
TBI or not TBI: that is the question. Is it better to measure toe pressure than ankle pressure in diabetic patients?
Brooks B, Dean R, Patel S, Wu B, Molyneaux L, Yue DK.
Diabet Med Jul;18(7):528-32

3. requirement is Blood Pressure cuff and doppler probe
ANKLE BRACHIAL INDEX
requirement is Blood Pressure cuff and doppler probe

4. Diagnostic criteria for abi
Table 1.
Interpretation Of Ankle-Brachial Pressure Index (ABI) Worksheet
Clinical Presentation
Ankle-Brachial Index
Normal
> 0.95
Claudication
Rest pain
Tissue loss
< 0.21
This is the typical chart for categorizing arterial
disease based on the ankle brachial index.
Note that ‘normal’ is a value greater than .95

5. ABI VALUES > 1.3 DIABETIC arteries
The hardening of the artery is due to the stiffening of the media layer of the arterial wall, but in contrast to intimal artery calcification, it does not obstruct the arterial lumen. The vessel may be resistant to collapse by the blood pressure cuff, and a signal may be heard at high cuff pressures. The persistence of a signal at a high pressure in these individuals results in an artifactually elevated blood pressure value. Rigid arteries (more than 1.3). If your ankle-brachial index number is higher than 1.3, this may mean that your arteries are rigid and don't compress when the blood pressure cuff is inflated. You may need an ultrasound test to check for peripheral artery disease instead of an ankle-brachial index test, or a toe-brachial index test, in which the blood pressures in your arm and big toe are compared.
Media calcifications
ABI VALUES > 1.3

6. P P G Photo - Pleths - moGraphy
PPG assesses blood flow by emitting an infrared light that is reflected by the red blood cells in superficial vessels and detected by the transducer. The amount of reflected light corresponds to pulsatile changes and tissue blood volume. PPG does not measure absolute blood flow, but it does provide a functional assessment of perfusion status.

7. Blood Pressure of the Toe is an alternative to ABI
Expensive Physiological
Testing Equipment
New Affordable TBI equipment
Although, the toe systolic pressure can be measured in the clinical setting using PPG, it has not been widely available or routinely performed in general clinical practice as it can be expensive. But new office based equipment is now available
Blood Pressure of the Toe is an alternative to ABI

8. Diagnostic Criteria for TBI
Toe Brachial Index
for reliable data
Diagnostic Criteria for TBI
Range Interpretation
> Normal
Mild
Moderate
< toe pressure 40 mmHg Moderate-Severe
<0.35 toe pressure < 30 mmHg Severe
From the Mayo Clinic Vascular Lab

9. ARTICLE REVIEWED
TBI or not TBI: that is the question. Is it better to measure toe pressure than ankle pressure in diabetic patients?

10. ….agreement between the tests (ABI vs TBI) when ABI is low or normal
>.7
.50 – .94
84% and 78% agreement in examining 227 subjects with Diabetes when the ABI is under 1.3

11. Patients with ABI > 1.3 have ABI-TBI differences outside this range
>1.3

12. Conclusion
In the majority of patients with diabetes, assessment of TBI conveys no advantage over ABI in determining perfusion pressure of the lower limbs. Only in those patients with overt calcification, which gives an ABI > or = 1.3, are toe pressure measurements superior.

13. Diabetes is the dominant risk factor for a high
The association between elevated ankle systolic pressures
and peripheral occlusive arterial disease
in diabetic and nondiabetic subjects.
Aboyans V, Ho E, Denenberg JO,
Ho LA, Natarajan L, Criqui MH.
J Vasc Surg Nov;48(5):
Diabetes is the dominant risk factor for a high
(> or =1.40) ABI. Occlusive PAD is highly prevalent in subjects with high ABI, and these subjects should be considered as PAD-equivalent.
Continued literature search on the topic of elevated ABI and TBI gave additional information about increased ABI and Arterial disease

14. Use and utility of ankle brachial index
in patients with diabetes.
Potier L, Abi Khalil C, Mohammedi K, Roussel R.
Eur J Vasc Endovasc Surg Jan;41(1):110-6.
….Therefore, ABI thresholds of less than 0.9 and more than 1.3 are highly suspicious for PAD and high CV risk in diabetic patients.
….the efficiency of ABI seems to be limited. In this case, other methods should be applied, toe pressure, in particular. Thus, the ABI could be used in patients with diabetes, but values should be interpreted with precision, according to the clinical situation.

15. Considerations
TBI is most reliable for monitoring patients with Diabetes
If TBI is not available, any patient with increased ABI > 1.3 should be suspected of having PAD
Duplex Arterial Scanning can help with identifying PAD in Diabetics with increased ABI