Skin Care

The benefits of wool-based products for tissue integrity

Wool contains unique properties that make it an effective tool for pressure-ulcer prevention

Gefen (2011) showed that skin breakdown increases with increased skin temperature, increased ambient temperature, increased relative humidity, increased skin contact pressure, and decreased permeability of materials touching the skin. Wool-based products are the ideal basis for tissue integrity solutions to meet these challenges, in that they minimise the influence of these elements identified by Gefen.

Moisture Reduction

Moisture build up next to the skin can lead to maceration of the skin at the surface, affecting the properties of the skin. Wool is hydrophilic, meaning that it takes up or wicks away moisture from the skin. Wool can hold up to a third of its weight of water vapour before ‘feeling’ wet, and therefore helps to protect against maceration, and leads to greater comfort.

Temperature Regulation

Temperature affects at the skin are important. Resting humans eliminate 25% of their basal metabolic rate through the skin. Sitting on a cold surface results in capillary closure, which in turn results in reduced supply and exchange of nutrients to the cells of the skin. As body temperatures rise, sweating increases. The air zone encapsulated by the fibres in wool insulates against the cold, while allowing the air to circulate when it gets hot. Wool’s ability to wick moisture assists the body’s natural cooling mechanism of sweating.

Friction and Shear Reduction

Friction from movement across surfaces causes shear displacement of body soft tissues, which can lead to long term tissue damage. The outer protein layer of the wool fibre is very smooth making the fibres slippery. This means the skin can move across a wool surface with lessened resistance. This also allows the fibres to move past one another easily, moving with the user rather than pulling on the skin, thereby reducing frictional forces. The ability of the wool pile to collapse sideways under pressure also reduces the shear forces. This varies according to the ‘nap’ of the wool in the support surface: there is less resistance in one direction than the other This is similar to the pile of an animal’s fur, which feels smooth when you stroke it one direction, and rough when the direction is reversed.

Pressure Redistribution

Pressure has been shown to be a major contributor to pressure ulcer incidence, with ulcers typically occurring in body areas which are subjected to high pressure.  
The high density of wool fibres found in medical sheepskin and in our XD1900 do a great job of redistributing pressure. This is because each fibre acts as a small spring: when multiplied out this produces a very supportive surface.

The benefits of wool-based products for tissue integrity
What is XD1900?

What is XD1900?

Extra Density, Extra Benefits

Healthcare Innovations Australia (HIA), following years of research, has brought XD1900 to the market. XD1900 is an extra high density woven wool material specially developed for skin and pressure care. Medical grade sheepskin has been proven to reduce the occurrence of pressure ulcers, but HIA wanted to go one step further and improve upon what nature could produce. Sheepskins are natural products, but Nature is variable. Natural sheepskin wool density varies from animal to animal, and can range from 800 to 1200 grams per square metre (GSM).

Our proprietary manufacturing techniques are able to take natural wool, and weave it into a density of 1900 GSM. Thereby we boosted the already impressive capabilities of natural sheepskin, and are able to manufacture a product that is consistent from batch to batch, and across the whole surface area. We can manufacture overlays up to the width of a bed without the need to join sections together,with less wastage and therefore cost savings for our customers. An additional benefit is that because we no longer have a leather or skin backing, XD1900 can be washed with standard detergents, for example in an institutional wash, at up to 100°C.

This novel process is also beneficial for the sheep, that can be shorn for their wool rather than being used for their skins. XD1900 also has less of an environmental impact, as it is a leather-free product so there are no chemical tanning agents needed to produce it.  

Natural vs Synthetic

XD1900 uses natural wool and a manufacturing process to achieve the extra density. It is the natural properties of wool that provide the protective and therapeutic benefits of our overlays.

  • Polyester and other artificial fibres were brought to the market because of their ease of washing at high temperatures, but they do not provide the resilience of wool fibres and are easily compressed and have minimal pressure redistribution properties.
  • Synthetic materials are also hydrophobic, so cannot provide the moisture absorbing properties of wool.
  • The high compressibility of synthetic products squeezes out trapped air, losing the temperature regulatory properties of natural materials.
  • Wool processing techniques have improved in the meantime, meaning that many wool based products such as XD1900 can be washed at or above 80°C. 

Synthetic 'fleece' products provide none of the health benefits of natural wool products.

Density

Accepting that wool is a more beneficial material than synthetics, the density of the wool fibres in an overlay is still very important for the therapeutic properties of the sheepskin. Lower densities compress too easily, removing the pressure redistribution, shear reduction, and temperature/moisture regulation properties of sheepskin. Over the years, low density (under 500 GSM), low-cost sheepskins have tarnished the image of natural sheepskins. Indeed these low density products have very limited clinical application. In our pressure mapping images you can see the comparison between the pressure distribution properties of a lower density woven wool product (700 GSM) and a Shear Comfort™ XD1900 (1900 GSM)

Clinical evidence - wool based products for tissue integrity

Clinical evidence demonstrates the effectiveness of medical sheepskin in preventing pressure ulcers

Three randomised clinical trials (RCTs) have been recently published which have demonstrated a positive impact on pressure ulcer (PU) rates comparing a significant number of patients using medical grade sheepskins with those without:

  • Mistiaen et al (2010) demonstrated a significant reduction of PU rates from 14.7 to 8.9% in a RCT with 588 subjects
  • Jolley et al (2004) in an open label randomized trial with 441 subjects demonstrated a 16.6% risk of PU without sheepskin vs 9.6% with a medical sheepskin (CL 95%)
  • McGowan et al (2000) showed in a trial with 297 subjects, a reduced PU rate of 9% on sheepskin, and as compared with 30% for those without.

Stacey (2004) wisely proposed that no individual strategy or device will completely resolve PU incidence. It is therefore appropriate to consider the physical properties that contribute to the observed beneficial effects of sheepskin in PU prevention.

Current views are that shear, heat, and water vapour, are significant contributing factors, together with pressure, in causes of tissue breakdown (NPUAP and EPUAP, 2009). Bain et al (2004) showed that natural sheepskin was comparable with plastic air-filled products for pressure redistribution, but had much better characteristics in relation to heat and water vapour dissipation.

Call et al (2010) confirmed these physical characteristics (which have a relevance for clinical benefits for tissue integrity) of natural sheepskins, but also the greater benefits of Shear Comfort™ XD1900 material in, for example, reducing the relative humidity against the skin.

Bain, C et al (2004) Pressure reducing overlays. MHRA Evaluation Reports
MHRA 04101-0.
Call, E et al (2010) ISO 16840 Testing for shear comfort XD1900 skin care material Proc EPUAP Sept 2010.
Jolley, DJ et al (2004) Preventing pressure ulcers with the Australian Medical
Sheepskin: an open-label randomised controlled trial. Med J Aust 180,324-327.
McGowan, S et al (2000) The role of sheepskins in preventing pressure
ulcers in elderly orthopaedic patients Primary Intention 8, 127-134.
Mistiaen, P et al (2010) The effectiveness of the Australian Medical Sheepskin for
the prevention of pressure ulcers in somatic nursing home patients: a prospective
multicenter randomized-controlled trial Wound Repair Regen 8, 572-9.
National Pressure Ulcer Advisory Panel and European Pressure Ulcer
Advisory Panel (2009) Prevention and treatment of pressure ulcers: clinical
practice guidelines National Pressure Ulcer Advisory Panel.
Stacey, MC (2004) Preventing pressure ulcers Med J Austr 180, 316-318.

Clinical evidence - wool based products for tissue integrity
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