Pressure Distribution

The wool fibres and staples, held intact by the tanned skin, enable the Australian Medical Sheepskin to provide support while relieving pressure by distributing the load of a patient over a large area, minimizing interface pressures.

The pressure distribution must be as uniform as possible with a highly deformable interface and a constant resistance to compression (1).

The fibre density and length must be such that the patient does not 'bottom out' on the skin surface and create localized pressure increases.

The following points support the claim for pressure relieving properties of sheepskins:

• At the simplest level, there is an enormous difference between sitting or lying on a mattress and sitting or lying on a sheepskin with a 30mm pile depth - the peak interface pressure, especially at pressure points such as bony prominences (eg. areas of the back, heels and elbows), is considerably reduced on the sheepskin.
• From a physical point of view, a woolskin deformed due to the weight of a patient supports a greater area of patient's skin than a mattress interface - the force per unit area on the patient's skin is therefore less on the sheepskin resulting in pressure reduction.
• The reduction in interfacial pressure between a patient and a mattress surface or sheepskin can be measured objectively (1) with a pressure sensor (2). It has been demonstrated (3) that the pressure reduction from a mattress interface to a sheepskin interface is greater than 50%.

In addition to pressure relief, woolskins could also be claimed to be of value for patient well-being and stress relief. Most patients find the sheepskins extremely comfortable, and many are reluctant to part with their sheepskin on discharge.

The increased wool-length now incorporated in the Australian Standard is a direct result of real-life comfort studies where the longer wool was statistically more comfortable than the shorter wool-lengths (20mm & 25mm).

1. Denne, Rheumatology and Rehabilitation, 1979, 18, 23. An objective assessment of the sheepskins used for decubitus sore prophylaxis.
2. Clark, CARE - Science and Practice, 1987, 5, 5. Continuous interface pressure measurement using an electropneumatic sensor: The SCP Monitor.
3. Montgomery, Reddie and Truong, Unpublished work, CSIRO Leather Research Centre, 1996.