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. 2018 Dec;15(6):866-874.
doi: 10.1111/iwj.12937. Epub 2018 May 24.

Effects of humidity on skin friction against medical textiles as related to prevention of pressure injuries

Danit Schwartz  1 , Yana Katsman Magen  1 , Ayelet Levy  1 , Amit Gefen  1
Affiliations

Effects of humidity on skin friction against medical textiles as related to prevention of pressure injuries

Danit Schwartz et al. Int Wound J. 2018 Dec.

Abstract

Sustained pressure, shear forces, and friction, as well as elevated humidity/moisture, are decisive physical factors in the development of pressure injuries (PIs). To date, further research is needed in order to understand the influence of humidity and moisture on the coefficient of friction (COF) of skin against different types of medical textiles. The aim of this work was to investigate the effects of moisture caused by sweat, urine, or saline on the resulting COF of skin against different textiles used in the medical setting in the context of PI prevention. For that purpose, we performed physical measurements of static COFs of porcine skin followed by finite element (FE) computational modelling in order to illustrate the effect of increased COF at the skin on the resulting strains and stresses deep within the soft tissues of the buttocks. The COF of dry skin obtained for the 3 textiles varied between 0.59 (adult diaper) and 0.91 (polyurethane dressing). In addition, the COF increased with the added moisture in all of the tested cases. The results of the FE simulations further showed that increased COF results in elevated strain energy density and shear strain values in the skin and deeper tissues and, hence, in an increased risk for PI development. We conclude that moisture may accelerate PI formation by increasing the COF between the skin and the medical textile, regardless of the type of the liquid that is present. Hence, reduction of the wetness/moisture between the skin and fabrics in patients at a high risk of developing PIs is a key measure in PI prevention.

Keywords: computational modelling; finite element analysis; pressure injuries; skin friction.

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Figures

Figure 1
Figure 1
Mechanical measurements of the porcine skin. A, The uniaxial compression testing setup. B, The 2‐bulb psychrometer used for relative humidity (RH) measurements. C, The tilting‐table tribometer used for friction measurements of the porcine skin against the different types of medical textiles
Figure 2
Figure 2
Computational model of the seated buttocks. A, A graphical illustration of the buttocks, showing the pelvic bones, muscles, fat, and skin tissues. The volume of interest is marked using a dasher red line. B, The boundary and loading conditions of the thin slice model. C, Zoom‐in on the tetrahedral mesh
Figure 3
Figure 3
Stress–strain curves of the 4 porcine skin samples that were experimentally tested in uniaxial unconfined compression
Figure 4
Figure 4
Comparisons of the coefficients of friction of porcine skin, dry and wet, with saline, sweat, or urine, rubbing against a standard cotton hospital bed sheet, a standard adult diaper, or a standard polyurethane foam dressing. Results are expressed as means ±1 SD
Figure 5
Figure 5
A, Distributions of strain energy density (SED) in the soft tissues of the buttocks, with the use of a high coefficient of friction (1.2, left) and a low coefficient of friction (0.6, right). B, An example time course of the distributions of shear strains, which develop under the influence of high coefficient of friction during sitting, from the time of initial skin‐cushion contact (t = 0) to full weight bearing (t = 1)
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