Fontaine et al developed the pressure/shear factor (PSF) to compare pressure and shear forces on a skin surface using different support surfaces. This can help select the support surface that is optimum for a patient. The authors are from the RIK Medical in Boulder, Colorado.


Basis: Both vertical pressure and shear forces can contribute to wound development by restricting blood flow and causing tissue breakdown.



(1) pressure in mm Hg

(2) shear force in grams



= ROUND(pressure in mm Hg) + (4 * ROUND(shear force))


When comparing 2 support surfaces, the surface with the lower PSF would be less likely to cause tissue injury.


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