A new way of measuring the performance of support surfaces: the Pressure Distribution Quotient

A new way of measuring the performance of support surfaces: the Pressure Distribution Quotient

Pressure and shear are among the main determinants that contribute to the development of pressure ulcers. Together with regular turning of a patient to alternate those anatomical areas that bear the bodyweight in a supine position, support surfaces play a crucial role in reducing both pressure and shear.

Performance of a support surface can be measured using pressure mapping. With this technique pressure redistribution as well as, within one anatomical area, the peak shear pressure (the difference between the highest and lowest pressure in that area) can be analyzed.

Envelopment also plays an important role in reducing pressure: the larger the surface over which a given weight is distributed, the lower the average pressure over that surface.

Given the importance of shear, pressure per se and envelopment, we propose a new way of analyzing shear, pressure and envelopment, the Pressure Distribution Quotient: data for all three elements are plotted in one graph, where the X-axis represents the peak pressure, the Y-axis the level of envelopment and the size of a plotted dot the shear pressure.

The coordinates on the graph indicate immediately the different properties of a surface (closer to the left and higher is superior) and this type of performance presentation allows for a better comparison of different types of support surfaces and, consequently, for a scientifically based decision on the choice of a support surface.