Dynamic foam mattress adapted for use with a variable length hospital bed

1. A patient support apparatus comprising:

a foam frame defining a space;

a bladder assembly positioned in the space, the bladder assembly including a plurality of foam-filled bladders, each of the foam filled bladders interconnected by a manifold, the manifold having an unpowered relief valve configured to release air from the bladder assembly if the pressure in the bladder assembly exceeds a predetermined limit of the relief valve; and

a cover enclosing the frame structure and the bladder assembly, the cover adapted to engage an articulated frame to control movement of portions of the foam frame and the bladder assembly in response to movement of the articulated frame,

wherein the cover includes a plurality of protrusions extending from a bottom surface of the cover, the protrusions adapted to be received in receivers formed in portions of the articulated frame to secure the cover to the articulated frame at a plurality of points, and

wherein a first at least one of the protrusions is secured to the foam frame and a second at least one of the protrusions is secured to the bladder assembly and the second at least one protrusion not secured to the cover.

2. The patient support apparatus of claim 1 , wherein the bladder assembly is secured to the cover at a second location spaced apart from a protrusion.

3. The patient support apparatus of claim 1 , wherein the cover is configured to include pockets that receive a portion of the bladder assembly to secure the bladder assembly to the cover at a second location spaced apart from a protrusion.

4. The patient support apparatus of claim 3 , wherein the bladder assembly includes a plate that floats relative to the remainder of the bladder assembly, the plate interconnecting the bladder assembly and cover at the second location.

5. The patient support apparatus of claim 4 , wherein the plate is semi-rigid but sufficiently pliable to be positioned in the pockets.

6. The patient support apparatus of claim 4 , wherein the bladder assembly further includes a bladder assembly cover that includes a sleeve formed in the bladder assembly cover and the plate is positioned in the sleeve and moveable relative thereto.

7. The patient support apparatus of claim 6 , wherein the second protrusion is secured to the bladder assembly cover.

8. The patient support apparatus of claim 1 , wherein the first protrusion is connected to a plate secured to the foam frame.

9. The patient support apparatus of claim 8 , wherein the plate is secured to the foam frame by a sleeve such that the plate floats within the sleeve.

10. The patient support apparatus of claim 9 , wherein the sleeve is secured to the foam frame by glue.

11. The patient support apparatus of claim 10 , wherein the foam frame includes a perforated foot section that is variable in length.

12. The patient support apparatus of claim 1 , wherein the foam-filled bladders each include a first layer and a second layer.

13. The patient support apparatus of claim 1 , wherein a first group of the plurality of foam-filled bladders has a first performance and a second group of foam-filled bladders has a second performance, different from the first performance, and wherein the difference in performance varies the support for a patient supported on the patient support apparatus between a head portion and a torso portion of the patient support apparatus.

14. The patient support apparatus of claim 1 , wherein the foam frame includes a perforated foot section that is variable in length.

15. The patient support apparatus of claim 1 , wherein each of the plurality of foam-filled bladders includes an unpowered check valve configured to open and permit atmospheric air to enter the respective bladder if the pressure in the bladder assembly is lower than the pressure of atmospheric air.

16. A patient support apparatus comprising:

a foam frame defining a space;

a bladder assembly positioned in the space, the bladder assembly including a plurality of foam-filled bladders, each of the foam filled bladders interconnected by a manifold, the manifold having an unpowered relief valve configured to release air from the bladder assembly if the pressure in the bladder assembly exceeds a predetermined limit of the relief valve; and

a cover enclosing the frame structure and the bladder assembly, the cover adapted to engage an articulated frame to control movement of portions of the foam frame and the bladder assembly in response to movement of the articulated frame,

wherein the foam-filled bladders each include a first layer and a second layer, wherein a first group of the plurality of foam-filled bladders has a first performance and a second group of foam-filled bladders has a second performance, different from the first performance,

wherein each of the bladders incudes a transparent window formed in a wall of an enclosure of the bladder,

wherein the cover includes a plurality of protrusions extending from a bottom surface of the cover, the protrusions adapted to be received in receivers formed in portions of the articulated frame to secure the cover to the articulated frame at a plurality of points, and

wherein a first at least one of the protrusions is secured to the foam frame and a second at least one of the protrusions is secured to the bladder assembly and the second at least one protrusion not secured to the cover.

17. The patient support apparatus of claim 16 , wherein the performance of a particular bladder is color coded and the transparent window is positioned to allow a user to identify the color of the bladder to identify the performance of the particular bladder by associating the color.

18. The patient support apparatus of claim 16 , wherein the bladder assembly is secured to the cover at a second location spaced apart from a protrusion.

19. The patient support apparatus of claim 16 , wherein the cover is configured to include pockets that receive a portion of the bladder assembly to secure the bladder assembly to the cover at a second location spaced apart from a protrusion.