An in vitro Study Investigating the Impact of Perspiration on the Coefficient of Friction Between Multilayered Wound Dressings and a Skin Substitute

Introduction: A high coefficient of friction (COF) between dressings and skin can increase soft tissue exposure to shear forces, raising the risk of pressure injuries. Many dressings used for pressure injury preven- tion (PIP) include an adhesive silicone skin-contact layer that transfers frictional forces inward, potentially counteracting their PIP effect. This study compared COFs of two multilayer dressings, one with a silicone skin-contact layer and one with a Hydrofiber skin-contact layer, in an in vitro model which accounted for perspiration. Methods: COFs were measured using a sled test based on ASTM D1894- 14. Dragon skin was cast at 3.5 mm. Dressings were applied to a 63.5x63.5 mm sled weighing 200 g, with an additional 3 kg for silicone dressings due to their high COFs. Simulated perspiration used a water/sodium/calcium ions solution, sprayed at 0.3 g increments. Sled speed was 150 mm/min. Results: At 5% and 10% dressing saturation, Hydrofiber COFs were 0.52 ± 0.05 and 0.28 ± 0.03 (static), and 0.47 ± 0.05 and 0.25 ± 0.02 (kinetic), showing no statistically significant changes as moisture levels increased. Regardless of dressing saturation level the COF values were significantly higher for silicone, at a 100% dressing saturation the COF values were 2.07 ± 0.20 (static) and 1.47 ± 0.17 (kinetic). Discussion: A novel multilayer dressing with Hydrofiber skin-contact layer* demonstrated lower COFs compared to silicone, reducing tissue shear exposure. Even in low-sweat areas, natural moisture accumulation could further minimise Hydrofiber COFs, making this beneficial for direct skin contact in a PIP dressing.