Improving the effect of shear on skin viability with wound dressings

Pressure ulcers are a major healthcare problem and caused by pressure and shear-forces. Although shear-force is understood to be a major contributing factor, no preventive interventions are specifically aimed at relieving the effect of shear on skin to improve skin viability.

A physical model was used to apply a combined loading of 2.4kPa pressure and 14.5N shear-force on skin in humans. Loading was applied on the volar aspect of both forearms for 30min in ten healthy volunteers. One arm received loading on skin with a wound dressing, the other arm (control) received loading directly on skin. The following parameters were determined before and after loading: IL-1α/Total Protein-ratio (used as a measure of skin damage); Cutaneous blood cell flux ((CBF) measure of reactive hyperaemia); Lactate concentration (measure of tissue ischemia). Three different dressings were tested on three different days. The order of dressing application, dressing arm and start of the intervention were randomized.

Participants mean age was 22.5±1.6 year with a BMI of 22.3±2.4kg/m(2). IL-1α/Total Protein-ratio of the skin was significantly lower after the application of pressure and shear when the Mepilex® (P<0.01), Allevyn (P<0.05) or Aquacel(TM) dressing (P<0.01) was used compared with the control measurement. The Mepilex® dressing was more effective in reducing post-load IL-1α/Total Protein-ratio compared to the Allevyn dressing (P<0.01). Post-load CBF was significantly lower when the Mepilex® or Aquacel dressing was used (P<0.001). Both dressings induced significantly less post-load CBF than the Allevyn dressing (P<0.01 and P<0.001, respectively). The concentration of lactate was not significantly increased after the application of pressure and shear and could not be used as a measure with this model.

This is the first in vivo study to demonstrate that the effects of pressure in combination with shear on skin viability can be improved with foam dressings. In this study, the multi-layered dressings perform better than the single-layered dressing.