Bertrand Lun

Leg symptoms of healthy people and their treatment with compression hosiery

Objectives Occasional leg symptoms, like feelings of heaviness and tension, and occupational or evening oedema are considered typical features of a venous disorder but show low specificity in epidemiological and observational studies. We evaluated the prevalence and nature of such symptoms in subjects with no history or signs of venous disease and investigated the optimal strength that medical compression stockings (MCS) should exert in order to alleviate the symptoms and to prevent leg swelling. Methods Specifically designed questionnaires were used to assess the symptoms of 40 healthy employees of a factory producing MCS. Lower leg volumes were quantified in the morning and evening. Calf size hosiery providing documented ankle pressures of 4–9 (mean 7.3), 12–18 (mean 14.9) and 18–22 (mean 19.5) mmHg, respectively, were tested in a prospective, open-label, randomized trial lasting three weeks. Endpoints were the relief of symptoms, prevention of vesperal oedema and comfort in wearing the stockings. Results Sixty-five percent of the participants reported at least occasional leg symptoms and oedema. Somatic-type symptoms (i.e. pain, heaviness, swelling, unattractive legs) were present in two, psychic-type symptoms (i.e. leg- and personality-related unrest and stress) in 17 and both components in seven of the 40 subjects. MCS exerting 15 and 20 mmHg prevented the symptoms and oedema. Stockings providing <10 mmHg were ineffective and those providing >19 mmHg were not well-tolerated. The effect on the somatic-type symptoms was strongly correlated with the amount of lower leg volume which could be reduced by wearing stockings (P = 0.005). No correlation was found between the efficacy of compression and the emotional component of the symptoms. Conclusion The cause of occasional pain in the legs of apparently healthy people is unknown. Some features of the syndrome reflect an emotional disorder while others mirror venous insufficiency. MCS of 15 mmHg effectively relieve the symptoms resembling venous insufficiency, prevent oedema and are well-tolerated.

Biomechanical response of varicose veins to elastic compression: A numerical study

A patient-specific finite-element (FE) model of the human leg is developed to model the stress distribution in and around a vein wall in order to determine the biomechanical response of varicose veins to compression treatment. The aim is to investigate the relationship between the local pressure on the soft tissues induced by wearing the compression garment and the development and evolution of varicose veins and various skin-related diseases such as varicose veins and ulcers. Because experimental data on the mechanical properties of healthy superficial veins and varicose veins are scarce in literature, ultrasound images of in vivo varicose veins are acquired and analysed to extract the material constants using Finite Element Model Updating. The decrease in trans-mural pressure, which conditions the effectiveness of compressive treatments, is computed from the simulation results. This constitutes the original added value of the developed model as decrease in trans-mural pressures cannot be assessed experimentally by any other means. Results show that external compression is effective in decreasing the trans-mural pressure, thereby having a positive effect in the control and treatment of vein-related diseases.

Prediction of the Biomechanical Effects of Compression Therapy on Deep Veins Using Finite Element Modelling

Clinicians generally assume that Medical Compression Stockings (MCS) work by reducing vein luminal diameter and, in this way, help to prevent blood pooling. Conflicting results have been reported however in the case of lower leg deep veins which call into question this hypothesis. The purpose of this contribution is to study the biomechanical response of the main lower leg deep veins to elastic compression and muscle contraction with the objective of improving our current understanding of the mechanism by which MCS convey their benefits. The development of a finite-element model of a slice of the lower leg from MR images is detailed. Analysis of the finite-element model shows that the contribution of the MCS to the deep vein diameter reduction is rather small, and in fact negligible, compared to that of the contracting muscle (3 and 9% decrease in the vein cross-sectional area with a grade II compression stocking in the supine and standing positions respectively, while complete collapse was obtained at the end of muscle activation). A more accurate representation of the muscle activation is eventually proposed to study the effect of muscle contraction on a vein wall. The impact on the venous blood draining is discussed.

Ease of Application of Medical Compression-stocking Systems for the Treatment of Venous Ulcers

OBJECTIVE To evaluate the ease of application of two-piece, graduated, compression systems for the treatment of venous ulcers. METHODS Four kits used to provide limb compression in the management of venous ulcers were evaluated. These have been proven to be non-inferior to various types of bandages in clinical trials. The interface pressure exerted above the ankle by the under-stocking and the complete compression system and the force required to pull the over-stocking off were assessed in vitro. Ease of application of the four kits was evaluated in four sessions by five nurses who put stockings on their own legs in a blinded manner. They expressed their assessment of the stockings using a series of visual analogue scales (VASs). RESULTS The Sigvaris Ulcer X((R)) kit provided a mean interface pressure of 46 mmHg and required a force in the range of 60-90 N to remove it. The Mediven ulcer kit exerted the same pressure but required force in the range of 150-190 N to remove it. Two kits (SurePress Comfort and VenoTrain Ulcertec) exerted a mean pressure of only 25 mmHg and needed a force in the range of 100-160 N to remove them. Nurses judged the Ulcer X and SurePress kits easiest to apply. Application of the VenoTrain kit was found slightly more difficult. The Mediven kit was judged to be difficult to use. CONCLUSIONS Comparison of ease of application of compression-stocking kits in normal legs revealed marked differences between them. Only one system exerted a high pressure and was easy to apply. Direct comparison of these compression kits in leg-ulcer patients is required to assess whether our laboratory findings correlate with patient compliance and ulcer healing.

Introducing knowledge of wearing compression stockings on the skin blood flow by using μHematron 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 μHematron ambulatory device. The investigation was performed for different postures using three standard French classes (10–15mmHg, 15–20mmHg and 20–36mmHg) 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 subjects 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.

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 skins 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.

Effect of compression stockings on cutaneous microcirculation: Evaluation based on measurements of the skin thermal conductivity

Objective To study of the microcirculatory effects of elastic compression stockings. Materials and methods In phlebology, laser Doppler techniques (flux or imaging) are widely used to investigate cutaneous microcirculation. It is a method used to explore microcirculation by detecting blood flow in skin capillaries. Flux and imaging instruments evaluate, non-invasively in real-time, the perfusion of cutaneous micro vessels. Such tools, well known by the vascular community, are not really suitable to our protocol which requires evaluation through the elastic compression stockings fabric. Therefore, we involve another instrument, called the Hematron (developed by Insa-Lyon, Biomedical Sensor Group, Nanotechnologies Institute of Lyon), to investigate the relationship between skin microcirculatory activities and external compression provided by elastic compression stockings. The Hematron measurement principle is based on the monitoring of the skin’s thermal conductivity. This clinical study examined a group of 30 female subjects, aged 42 years ±2 years, who suffer from minor symptoms of chronic venous disease, classified as C0s, and C1s (CEAP). Results The resulting figures show, subsequent to the pressure exerted by elastic compression stockings, an improvement of microcirculatory activities observed in 83% of the subjects, and a decreased effect was detected in the remaining 17%. Among the total population, the global average increase of the skin’s microcirculatory activities is evaluated at 7.63% ± 1.80% (p < 0.0001). Conclusion The results from this study show that the pressure effects of elastic compression stockings has a direct influence on the skin’s microcirculation within this female sample group having minor chronic venous insufficiency signs. Further investigations are required for a deeper understanding of the elastic compression stockings effects on the microcirculatory activity in venous diseases at other stages of pathology.

A new hybrid protocol enabling to evaluate the pressure level of medical compression stocking in patients: "ex-vivo procedures".

Introduction Medical compression treatment using stockings exerts a pressure to the vascular system which represents the therapeutic dose. This pressure is indirectly measured according to heavy laboratory tests based on calibrated artificial leg markings. The objectives of this work were to elaborate and test a new dynamometer which allows direct measurement of pressure from how the stocking is applied by the patient and whatever the leg curvature radius are. Method A portable mini dynamometer (Modyn) that reproduces the testing in textile laboratories was elaborated. To test the reliability of this device four sizes, each size available in three lengths, of anti-thromboembolic medical compression stockings were measured at the ankle level using both the Modyn and the reference textile laboratory dynamometer. All the measurements were blindly performed. The measurement procedure followed the G 30 102 B French norm. Results On a total of 72 measurements, the explained variance between both methods was r= 0.92 and the correlation coefficient r= 0.96. The intra-operator repeatability of the Modyn provided a mean value of 22.12 mmHg, SD 0.74. Conclusion This portable, easy to use, pressure measurement device using the dynamometer principle, is a reliable field tool that should be used in future clinical trials to measure more precisely what the patients treated by compression stockings really receive as therapeutic pressure.