New device for assessing the toe-brachial index and a pilot cross-sectional study in diabetic patients.

Background: Blood pressure measurements in the hallux and fingers are important in evaluation of patients with diabetes, obese patients, dialysis patients, and those with peripheral artery disease.

Objectives: In this article, we tested a prototype of an automatic device for measuring systolic pressure in fingers and toes, combining optical plethysmography and a pressure sensor, with a cuff encircling the finger or toe, and controlled by a microcontroller.

Methods: The prototypes (a total of 3 identical devices) were tested for initial validation (with a group of participants who already had symptoms of peripheral arterial disease [PAD], n=30) and also in clinical comparisons between controls (n=15) and participants with diabetes (n=15). The following variables were tested: Ankle-brachial index; Toe-finger index; Toe-brachial index, and toe pressure in isolation. For validation, the toe pressure in isolation was measured with two devices (the prototype under test and the SysToe® device), to analyze the correlation between the two measurements.

Results: The correlation between the two devices was strong (R=0.88) in the group with symptoms of PAD. Toe-brachial index was lower in patients with diabetes than in control participants (p=0.005) as was the Toe-finger index (p=0.03), however, the Ankle-brachial index was similar in these two groups (p=0.92).

Conclusions: The findings show the feasibility of the device for measuring finger and toe pressures, and possibly indicate greater sensitivity for detecting early-stage arterial disease using this type of measurement.