The biomechanical efficacy of a hydrogel-based dressing in preventing facial medical device-related pressure ulcers

Abstract

Continuous positive airway pressure masks for breathing assistance are used widely during the coronavirus pandemic. Nonetheless, these masks endanger the viability of facial tissues even after a few hours because of the sustained tissue deformations and extreme microclimate conditions. The risk of developing such device-related pressure ulcers/injuries can be reduced through suitable cushioning materials at the mask-skin interface, to alleviate localised contact forces. Here, we determined the facial tissue loading state under an oral-nasal mask while using hydrogel-based dressing cuts (Paul Hartmann AG, Heidenheim, Germany) for prophylaxis, which is a new concept in prevention of device-related injuries. For this purpose, we measured the compressive mask-skin contact forces at the nasal bridge, cheeks, and chin with vs without these dressing cuts and fed these data to a finite element, adult head model. Model variants were developed to compare strain energy densities and effective stresses in skin and through the facial tissue depth, with vs without the dressing cuts. We found that the dry (new) dressing cuts reduced tissue exposures to loads (above the median loading level) by at least 30% at the nasal bridge and by up to 99% at the cheeks, across the tissue depth. These dressing cuts were further able to maintain at least 65% and 89% of their protective capacity under moisture at the nasal bridge and cheeks, respectively. The hydrogel-based dressings demonstrated protective efficacy at all the tested facial sites but performed the best at the nasal bridge and cheeks, which are at the greatest injury risk.

Keywords: MDRPUs; biomechanical model; computer finite element simulations; pressure injury prophylaxis; prophylactic dressings.

FIGURE 1

Determination of the contact forces generated by a continuous positive airway pressure (CPAP) mask on facial skin and their application in the computational modelling: A, Experimental measurements of the contact forces with the CPAP mask in five head sites, namely, the nasal bridge (Position #1), the two cheeks (Positions #2 and #3), the chin (Position #4), and the back of the head (Position #5). The latter sensor position was used to ensure a good fit of the CPAP mask for each subject. The contact forces were measured in Positions #1 to 4 with and without application of the hydrogel‐based dressing cuts (as depicted in the left frame). B, Two corresponding computational finite element model variants were developed, with vs without the applied dressing cuts. The measured contact forces at the nasal bridge (F _nose ), the cheeks (F _cheek ), and the chin (F _chin ) were used as force boundary conditions to simulate the strapping of the CPAP mask onto the head

FIGURE 2

The contact force data measured in the subject group at the three facial sites of interest, with vs without the protection of the hydrogel‐based dressing cuts. The error bars show the standard deviations (N = 6) and the asterisk is for P < 0.05

FIGURE 3

The distributions of facial tissue loads determined by means of the computational finite element modelling: A, Strain energy density (SED) and B, effective stresses in skin. Both the SED and effective stress data exhibit greater values for the “no dressing” case with respect to the ‘dressing’ cases, either in dry or moist conditions

FIGURE 4

Model calculations of the exposure of facial skin (only) to strain energy density and effective stresses in the A, chin, B, nasal bridge, and C, cheeks, with vs without the protection of hydrogel‐based dressing cuts in their dry and moist conditions

FIGURE 5

Model calculations of the exposure of facial skin and subcutaneous fat (“pooled soft tissues”) to strain energy density and effective stresses in the A, chin, B, nasal bridge, and C, cheeks, with vs without the protection of hydrogel‐based dressing cuts in their dry and moist conditions