Valitrack study: Objective evaluation of medical compression wearing time and patient activity with the Accutrack® by Sigvaris Group sensor.

INTRODUCTION: Objective measurement of compliance is mandatory to evaluate therapeutic effects and clinical benefits of medical compression stockings. This Valitrack study evaluates the Accutrack sensor equipped with an accelerometer. The evaluation is done under controlled and free conditions and during washing. RESULTS: Global accordance results are excellent: Sensitivity (98.6%) and specificity (95.2%) and 92% of patients are not disturbed by the sensors when putting on the stockings. DISCUSSION: Thanks to its specificities one sensor per patient is sufficient. Its sensitivity distinguishes still and active positions. Only hand washing remains a false positive. The Accutrack sensor objectively measures compliance and will not be a bias because 96% of patients forget it. CONCLUSIONS: Objective compliance measurement with Accutrack allows us to evaluate the efficacity of compression, the reasons of non-compliance, and the patient's actual physical activity according to its accelerometer time-stamped.

Comparison between bioelectrical impedance spectroscopy measurements and water volume displacement of ankle oedema variations during the course of a day.

OBJECTIVE: The purpose of this study was to find relationships between variations in bioelectrical impedance spectroscopy (BIS) measurements and those obtained by water displacement (WD) and calf (C) and ankle (A) perimetry on legs of patients with venous insufficiency and lower limb oedema, some with positive pitting test (PPT), others with negative pitting test (NPT). APPROACH: Twenty-nine (29) female subjects were clinically examined prior to inclusion in the trial. Measurements were taken once in the morning and then 6 h later, using perimetry, WD, and then BIS; subjects were standing. Leg volume was assessed using two WD volumeters, one 'Tall' (TWD) and one 'Short' (SWD). BIS was performed using a SFB7 impedance meter device (Impedimed®). MAIN RESULTS: Forty-three (43) legs with oedema were included. The results showed that 61% of the TWD variations variance was explained by SWD variations; less than 30% of the TWD variations variance was explained using BIS or perimetry alone, and 45% at best when used in combination. R0, related to extracellular water, was the key BIS parameter. For NPT subpopulation (32 legs), the composite parameter (C2 - A2)/R0 explained more than 60% of the TWD variations variance. For PPT subpopulation (11 legs), small or statistically non-significant variance explanations were found. SIGNIFICANCE: Combination of anthropometric and BIS parameters gave a better forecast of WD results than using only one or other. A novel composite parameter, (C2 - A2)/R0, better predicted TWD changes than other parameters hitherto used in literature, with improved estimates for the NPT subpopulation. Study n°ANSM 2017-A01063-50.

Ambulatory sensor for circumference monitoring of lower limbs.

The continuous monitoring of edema in the lower limbs of the human body is presently not possible as suitable devices are not available. This paper presents the characterization and the testing of a novel ambulatory device dedicated to the monitoring of circumference variations in the lower limb. The sensor, based on an inductive loop integrated into a textile band, is connected to a miniaturized electronic system which wirelessly sends the calculated perimeter value of the leg to a smart mobile device. In-vitro tests have demonstrated that the device enables the measurement of perimeters ranging from 25 cm to 33 cm with an accuracy of 0.3 cm. This result was obtained using a circular loop, which assumes that the shape of the leg remains circular at the location where the loop is positioned. To investigate the influence of the loop shape on the sensor response, three physical models of different shapes (circular, elliptic and triangular) were tested. It was found that self-inductance values of the loop can be predicted in an acceptable way using a theoretical model for the three different shapes. Experimental tests showed that the error in the perimeter value is around 5% of the full scale when changing the geometry from circular to elliptic but can reach 11 % from circular to triangular. The application interface developed for a smartphone is presented, which will enable the ambulatory monitoring of leg edemic swelling during daily activity and facilitate its assessment by the clinician.

Local effect of compression stockings on skin microcirculatory activity through the measurement of skin effective thermal conductivity.

This paper presents a preliminary study to demonstrate the instantaneous local effect of compression stocking (Class 2) on skin microcirculatory activity. The measurement needs to be carefully performed as the sensor is placed under the garment. To assess the local effect of compression stockings, we use the ambulatory device Hematron located on the calf under the garment. Skin microcirculatory activity is assessed through the skin's effective thermal conductivity measurement. A specific housing for the sensor has been designed to avoid excessive pressure induced by the sensor when squeezed by stockings. The experiment, conducted on ten healthy subjects, comprised two stages: without and with compression stockings. Skin effective thermal conductivity was recorded at three successive positions (supine, sitting and standing). Significant improvement in skin microcirculatory activity was recorded by the Hematron device for the three positions. We have also demonstrated that Hematron sensor can be used under compression stockings.

ActimedARM - design of a wearable system to monitor daily actimetry.

We developed a low power kinematic sensor, ActimedARM, incorporating three-axis accelerometer and magnetometer, a microcontroller ARM3, a ZigBee wireless communication and µSD memory storage. With embedded algorithms it can detect in real time the postures of the subject. A preliminary assessment conducted on 12 subjects reached a 97% correct classification rate. The device exhibits 32 days of autonomy on a 3600 mAh capacity battery, which makes it convenient for field experiments in true daily life.

Introducing knowledge of wearing compression stockings on the skin blood flow by using microHematron device.

The aim of this preliminary study was to review the actual state of knowledge concerning the mechanisms underlying compression medical stockings action on the skin blood flow (SBF) in capillaries. SBF was assessed by measuring the thermal conductivity of living-tissues using microHematron ambulatory device. The investigation was performed for different postures using three standard French classes (10-15 mmHg, 15-20 mmHg and 20-36 mmHg) of Medical compression stockings (MCS) on six healthy subjects without chronic venous insufficiency. The experiment was divided into four stages (supine, sitting, standing and walking) and was repeated for each class of compression stockings and without MCS. The results showed a significant improvement of SBF depending on the class of MCS used. Best results were obtained for the Class III, which exerts to the highest level of pressure exerted around the ankle. Due to the low number of subjects, which therefore reduces the statistical relevance of results, a non-significant difference in SBF due to the subject's posture was observed. Nonetheless, a positive action by all the classes of MCS on SBF was measured for the supine position. This is a very important result; with patients with chronic venous insufficiency have often some mobility reduction, MCS may enhance their microcirculation even at rest.