Study by University of Helsinki finds high reliability and repeatability of the MESI mTABLET TBI compared to Doppler

Study authors: Laamanen P, Laivuori M, Noronen K, Venermo M. The authors come from the
Department of vascular surgery, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.

The University of Helsinki and the Helsinki University Hospital carried out a study to assess the reliability of a toe pressure photoplethysmography (PPG) device in comparison to a stationary laser Doppler flowmeter. In this, the MESI mTABLET TBI was used as the PPG device, and compared to a Doppler flowmeter device.

The study found that the MESI mTABLET TBI showed excellent repeatability, with the results of two measurements on the same toe differing by only 4 mmHg on average. It also recognised 9 out 10 patients with ischemia when the threshold was 60 mmHg. It was therefore denoted as a practical, affordable option for assessing lower limb arterial insufficiency and reducing unnecessary referrals to secondary care. In this, a holistic approach to the patient is recommended: the results should always be interpreted in consideration of the patient’s clinical status. [1]

You can take a look at the study here.

The background

Accurate and timely diagnosis of Peripheral Arterial Disease (PAD) is critical for preventing severe health consequences such as amputations, strokes, and cardiovascular events. In this, Ankle-Brachial Index (ABI) is extensively used, also in primary care, but has some limitations. [1]

Firstly, it can be unreliable in certain patient groups, e.g. in diabetic patients who have non-compressible crural arteries. In this case, Toe-Brachial Index (TBI) measurement can be used because mediocalcinosis in digit arteries is less prevalent. Secondly, even with normal ABI results, any suspicion of chronic limb-threatening ischemia (CLTI) should be investigated with TBI. [1]

Toe-Brachial Index (TBI) helps confirm the diagnosis of PAD in primary care, and is also used in the assessment of cardiovascular risk factors; it has been suggested that TBI measurement should take place routinely because TBI is predictive of cardiovascular mortality. [3] [4] However, the use of TBI is not so common in primary care although automated photoplethysmography-based TBI devices are easily portable. TBI measurement is chiefly performed in secondary care, which is problematic as it means harder and delayed access to this diagnostic test. Early detection of conditions like CLTI is namely crucial for patients with diabetic foot, who need vascular treatment referral as soon as possible. [1]

For the above reasons, the study by the University of Helsinki and the University Hospital of Helsinki focused on the reliability and reliability of photoplethysmography (PPG) devices compared to laser Doppler flowmeter, regarded as gold standard for superficial microvascular assessment. [2]

The study consisted of measuring 102 toes of 54 participants, who were mostly pre- and post-surgical patients from the department of vascular surgery at the Helsinki University Hospital. The measurements on each patient took place on the same day with both devices, mostly within an hour of each other. To assess the reliability of the MESI mTABLET TBI, the Toe-Brachial Index was measured twice, with 15 minutes in-between the measurements. If they differed by more than 10 mmHg, a third measurement was performed. [1]

The findings

The Toe-Brachial Index measurements using the MESI mTABLET TBI identified 9 out of 10 patients with significant ischemia (TP <60 mmHg) when compared to the laser Doppler flowmeter. The MESI mTABLET TBI was able to detect 87.5% of patients with significant arterial insufficiency (TP <60 mmHg) identified by the laser Doppler flowmeter. Conversely, 84.8% of limbs without ischemia according to the laser Doppler flowmeter also had a TP of ≥60 mmHg when using the MESI mTABLET TBI. [1]

The study concludes that the use of portable PPG devices like the MESI mTABLET TBI may improve the accuracy of PAD diagnosis in primary care, reduce the number of unnecessary referrals for vascular treatment, and thus contribute to treatment cost-effectiveness. However, the results must be interpreted in consideration of the patient’s clinical status. [1]

What is Toe-Brachial Index?

The Toe-Brachial Index (TBI) is a diagnostic method used for the diagnosis of Peripheral Artery Disease (PAD). It is used when the Ankle-Brachial Index (ABI) measurement is uninterpretable or insufficient. Read more

When to do Toe-Brachial Index?

TBI measurement is recommended for diabetic patients, patients undergoing dialysis, patients with advanced age, patients with extensive wounds, and patients with lymphoedema. Read more

How to measure Toe-Brachial Index?

The Toe-Brachial Index (TBI) is measured by comparing the blood pressure in the (usually large) toe to the blood pressure in the arm (brachial artery).