This invention relates to patient support surfaces and positioners and more particularly to pressure management and skin shear-reducing surfaces and positioners. 
Care providers are well aware that patient support surfaces and positioners can play a significant role in the creation or prevention of pressure ulcers.  Patients undergoing surgical procedures, medical procedures, or recovery from the same, have their entire body and/or portions of their body supported by patient support surfaces and positioners.  Portions of the patient""s skin may be subjected to very high pressures and shear forces exerted by the material underlining skin resulting in tissue loads that restrict blood flow to a particular area of the skin resulting in tissue damage or necrosis.  This is a major cause of pressure ulcers. 
The described invention reduces the risk of skin shear and decreases tissue load.  The disclosed surfaces and positioners distribute the patient""s weight more evenly across the surface to significantly decrease pressure on the body""s bony prominences.  The disclosed surfaces are designed to cradle the patient and reduce pressure on the bony prominences, thus reducing patient interface pressure.  This facilitates effective distribution of the patient""s tissue load evenly over the surface.  This is accomplished in certain preferred embodiments by using a highly stretchable cover overlying the patient supporting surface of a cushion adapted to more evenly distribute the patient""s weight.  The cushion may be an air cushion, a foam pad, or a combination of foam pads having different densities and recovery ratings, an air impregnated gel, or any combination of these cushioning materials. 
Decreasing interface pressure between the support surface and the patient does not necessarily reduce skin shear.  Similarly, it is known that common gel overlays which significantly reduce skin shear can actually increase interface pressure.  The present invention comprises an anti-shear liner or layer which combines the four-way stretch cover material with a friction-reducing and anti-shear layer. 
A patient support surface or positioner according to the present invention includes an anti-shear liner, a cover, and a cushion layer.  The anti-shear liner is disposed in selected areas between the cover and the cushion layer to allow the cover to slip in such selected areas relative to the cushion layer.  The cover is preferably configured to be highly stretchable.  The cover preferably may be a rubber-like material which is characterized by its stretchability in one direction being greater than its stretchability in an orthogonal direction.  When the patient support is longitudinally extending with a foot end and a head end, a stretchable cover may be positioned on the support so that it is more stretchable in the longitudinal direction. 
The cushion may be formed by a plurality of air cavities, a plurality of foam layers, gel material, or any combination thereof.  The foam layers may be selected from a group of slow recovery foam, low density foam, high density foam, reduced density foam, medium density foam, and closed cell foam.  The air cushion may include a plurality of sealed air bladders in combination with inflatable bladders.  Foam layers may be used in different combinations in different areas of the support, to support different areas of the patient""s body differently.  Likewise sealed air bladders and inflatable air bladders may be used in different combinations and in different areas of the surface, to support different parts of the patient""s body differently.  The anti-shear layer may be disposed under the entire patient supporting surface of the cover or under selected portions of the cover, depending upon the surface characteristics desired. 
A process of distributing patient weight and minimizing shear on the patient""s skin includes the steps of providing a cover, providing a cushion, and providing an anti-shear layer over selected portions of the cushion.  The combination of the cover, anti-shear layer, and cushion, with the anti-shear layer disposed between the cover and the cushion, is placed on a patient support such as a surgery table, bed or stretcher.  The anti-shear layer is preferably selectively positioned under the cover to provide an area having less resistance to cover stretching and movement relative to the cushion. 
According to another aspect of the disclosed invention.  A patient support includes air bladders made of anti-shear material and a stretchable cover placed over the air bladders. 
According to still another aspect of the disclosed invention, a surface for a patient support or part thereof includes a series of inflatable air bladders made from anti-shear material which are disposed to provide a cushion under the patient with the highly stretchable cover over the air bladders.  A viscoelastic foam layer may be disposed between the cover and the air bladder.  At least one of the plurality of inflatable air bladders may be disposed within a permanently sealed and inflated bladder. 
In some embodiments of the present invention a cover may not be highly stretchable as that term is hereinafter defined.  Thus, in this specification and particularly in the claims, unless the cover is specified as xe2x80x9chighly stretchablexe2x80x9d, it shall not be limited to such characteristics. 
Additional features of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of the preferred embodiment exemplifying the best mode of carrying out the invention as presently perceived.