Body supporting mattress

Claim 1

A body supporting mattress which, when used by bedridden patients, minimizes formation of decubitis ulcers, said mattress comprising: a first plastic unit which is flat and horizontal and is adapted to be placed upon a bed, said first unit being provided with a peripherally disposed horizontal endless hollow air filled inflatable tube, said tube defining a raised peripheral border surrounding and enclosing an inner flat horizontal central area of the first unit, said tube being hard when filled with air and having a first vertical height above said central area; and at least one second plastic unit which is removably disposed on top of said central area, said second unit having an upper section having oppositely disposed inner and outer surfaces, the outer surface being disposed above the inner surface and permanently defining a plurality of closely spaced raised regions which are interconnected by channels disposed below the top surfaces of the regions, the inner surface permanently defining a like plurality of deep recesses, each deep recess constituting the inside of a corresponding region, the deep recesses being interconnected by shallow recesses, each shallow recess constituting the inside of a corresponding channel, said second unit having a lower section which is essentially flat and horizontal and is sealed to the inner surface of the first section in such manner that the deep and shallow recesses communicate with each other but do not communicate with said tube, said deep and shallow recesses being filled with water, said raised regions having a second vertical height above said central area, the second height being lower than said first height, the water filled regions and channels being softer than said air filled tube.