Hrev_master Veins and Lymphatics 2018; volume 7:7628 [Veins and Lymphatics 2018; 7:7628] [page 69] A new stocking compression system with a low well-defined resting pressure and a high working pressure Andreas Nilsson,1 Torbjörn Lundh1,2 1PressCise, Herrljunga; 2Chalmers University of Technology, Gothenburg, Sweden Abstract Compression stockings should prefer- ably apply the intended pressure regardless of leg shape and circumference. This may require custom fitting.1 Today’s sizing sys- tem is focusing on the exerted pressure at the ankle region. A ready-made stocking may therefore exert correct pressure at the ankle, but the pressure at the calf may be well exceeded due to the actual size of the calf, leading to a tourniquet effect, ischemia or even increased risk of thrombosis.2 Even with a perfectly-fitted stocking, the problem with changes in leg circumference due to the increase/decrease in oedema is not resolved.3,4 Stocking donning problems vary with compression class and elasticity of the material used. Added pressure over the calf area has been reported to improve venous pumping function more than gradu- ated compression.5,6 Adding stiffness over the calf area may also improve the pumping function.7 Häfner et.al. stated that “Hemodynamically optimal compression products will make medical compression therapy an even more useful tool in the field of phlebology”.8 With new smart textiles, the pressure can be controlled.9 The aim was therefore to evaluate a prototype of a stocking compression system with specified well-defined target resting pressure and supposedly high working pressure created by stiffness. Materials and Methods Included in this limited study were eight healthy subjects (5 women and 3 men). A novel compression system (Lundatex® Stocking System, PressCise, Sweden) con- sisting of a highly elastic stocking designed for 18 20 mmHg resting pressure without graduated pressure was used as a first layer. The stocking consisted of a patented smart textile with pressure specified to be well- defined regardless of leg circumference and shape. As a second layer, patches consisting of hook-material (similar functionality to Velcro) was applied. The second layer con- verts the system from elastic to stiff. The transformation of an elastic first layer into a stiff system has previously been studied with respect to interface pressure, stiffness, and haemodynamic effectiveness10. The patches were applied from about 5 cm above the malleoli to a point 3 cm below the top of the stocking. Interface pressure between stocking and skin were recorded (Picopress®, Microlab, Italy) unilaterally on all subjects. To evaluate the pressure pro- file as well as the pressure with respect to leg circumference, the interface pressure was measured at the B1 point which is defined as the point where the medial gas- trocnemius muscle turns into the tendinous part and the C point at maximum leg-cir- cumference. The static stiffness index (SSI)11 was calculated. A Mann-Whitney U- test was used for comparisons and signifi- cance was set at P < 0.05. Correlations are given with Pearson’s r. Unless otherwise stated, all results are given as the mean and standard deviation (SD). Results The first layer, the stocking, with speci- fied pressure 18-20 mmHg exerted well- defined target pressure (Table1). The pres- sure was uniform and showed low correla- tion to leg circumference (r=0.2) despite circumferences varying from 23 to 39.5 cm [Fig1]. A pressure increase was noted in supine position when patches were applied, 5 mmHg (P<0.003) at B1 and 6 mmHg (P<0.001) at C. With the second layer the system turned from an elastic system with low SSI (Table1) to a stiff product with high SSI (Table2). Discussion The compression system applies a well- defined resting pressure regardless of the circumference of the leg, despite the fact that the same stocking was used on all sub- jects. This indicates that a limited number of stocking sizes may cover the whole range of leg sizes, and that custom fitting will not be required. A high working pressure was achieved by the stiff second layer. The low resting pressure and high working pressure gives the system a high SSI. The moderate increase in pressure when the patches were applied may be reduced by instructions to the applier of the system to avoid using extra stretch when putting on the patches. The subjects found the stocking easy to put on. A probable reason for this is the high elasticity of the stocking. There is reason to assume that the low resting pressure and high working pressure may be maintained over time even after reduction of oedema by opening and closing the front patch on the system, since this approach has successfully been used previously.12 Future studies should investigate the pressure over time as well as the haemodynamic effectiveness of the system. Correspondence: Andreas Nilsson, PressCise, Herrljunga, Sweden. E-mail: andreas@presscise.com Conference presentation: International Compression Club (ICC) Meeting, Paris, 2017. This work is licensed under a Creative Commons Attribution 4.0 License (by-nc 4.0). ©Copyright A. Nilsson and T. Lundh, 2018 Licensee PAGEPress, Italy Veins and Lymphatics 2018; 7:7628 doi:10.4081/vl.2018.7628 Figure 1. First layer-stocking only. Low correlation was found between Interface pressure measured in supine position and leg circumference. No n- co mm er cia l u se on ly Conference Presentation [page 70] [Veins and Lymphatics 2018; 7:7628] Conclusions This new prototype stocking compres- sion system shows promising properties, with low defined resting pressure and high working pressure independent of leg cir- cumference and shape, despite a minimum of measuring and fitting requirements. References 1. Liu, Rong, et al. "Stratified body shape- driven sizing system via three-dimen- sional digital anthropometry for com- pression textiles of lower extremities." Textile Research Journal (2017): 0040517517715094. 2. Classification of compression stock- ings, ICC derived 120118 from: http://www.tagungsmanagement.org/ic c/images/stories/PDF/pressureranges.p df. 3. Nørregaard, Bermark, and Gottrup. "Do ready-made compression stockings fit the anatomy of the venous leg ulcer patient?." Journal of wound care 23.3 (2014): 128-135. 4. van der Wegen-Franken, C. P. M., et al. "Changes in the pressure and the dynamic stiffness index of medical elas- tic compression stockings after having been worn for eight hours: a pilot study." Phlebology 24.1 (2009): 31-37. 5. Mosti and Partsch, (2014) "Improvement of venous pumping function by double progressive com- pression stockings: higher pressure over the calf is more important than a gradu- ated pressure profile." European Journal of Vascular and Endovascular Surgery 47.5:545-549. 6. Mosti and Partsch (2012) "High com- pression pressure over the calf is more effective than graduated compression in enhancing venous pump function." European Journal of Vascular and Endovascular Surgery 44.3:332-336. 7. Partsch H, Mezinger G, Mostbeck A. Inelastic leg compression is more effec- tive to reduce deep venous refluxes that elastic bandages. Dermatol Surg. 1999;25:695-700 8. Häfner, Piche and Jünger. The ratio of working pressure to resting pressure under compression stockings: its signif- icance for the development of venous perfusion in the legs. Phlebologie 2001;30:88-93. 9. Wiklander, Erichsen Andersson and Källman.(2015) "An investigation of the ability to produce a defined ‘target pressure’ using the PressCise compres- sion bandage." International wound journal. 10. Mosti and Partsch (2017). A New Two Component Compression System Turning an Elastic Bandage into an Inelastic Compression Device: Interface Pressure, Stiffness, and Haemodynamic Effectiveness. European Journal of Vascular and Endovascular Surgery. 11. Partsch. The static stiffness index: A simple method to assess the elastic property of compression material in vivo. Derm Surg 2005;31:625e30. 12. Damm, Lundh, Partsch and Mosti. An innovative compression system provid- ing low, sustained resting pressure and high, efficient working pressure. Veins Lymphatics 2017;6:6627. Table 1. First layer-stocking only. Interface pressures (mmHg) in supine and standing position with SSI. Sensor position Supine Standing SSI Mean SD Mean SD Mean SD B1 18 1.1 18 2.2 0.1 2.4 C 19 1.4 19 1.5 0.4 0.5 Table 2. System-stocking with patches. Interface pressures (mmHg) in supine and standing position with SSI. Sensor position Supine Standing SSI Mean SD Mean SD Mean SD B1 23 3.3 44 14 21 13 C 25 2.3 40 9.2 23 7 No n- co mm er cia l u se on ly