Mattress and method for preventing accumulation of carbon dioxide in bedding

Abstract

A mattress assembly, comprising: substantially nonporous bottom and side walls forming a mattress foundation; a mattress inner core disposed in the mattress foundation being permeable to air; nonporous top cover covering the mattress inner core, the nonporous top cover having apertures at predetermined locations to allow the flow of air therethrough; and a fan disposed with the mattress assembly for forcing air into the mattress inner core whereby the air is forced out the top cover so as to reduce the accumulation of carbon dioxide in bedding on the top cover of the mattress.

Description

BACKGROUND OF THE INVENTION

The present invention relates to an apparatus and method for preventing the accumulation of carbon dioxide in bedding which is believed to be a cause or contributing factor in Sudden Infant Death Syndrome (SIDS).

Many efforts have been made to produce a mattress assembly which will prevent or reduce the occurrence of SIDS. Unfortunately, most of these approaches do not offer a good solution. The present invention solves many of the problems or shortcomings of the prior art mattress assemblies.

SUMMARY OF THE INVENTION

The present invention relates to an apparatus and method for preventing the accumulation of carbon dioxide in bedding which is believed to be a cause or contributing factor in Sudden Infant Death Syndrome (SIDS).

In one embodiment, the invention relates to a mattress assembly, comprising: substantially nonporous bottom and side walls forming a mattress foundation; a mattress inner core disposed in the mattress foundation being permeable to air; a nonporous top cover covering the mattress inner core, the nonporous top cover having apertures at predetermined locations to allow the flow of air therethrough; and a fan disposed with the mattress assembly for forcing air into the mattress inner core whereby the air is forced out the top cover so as to reduce the accumulation of carbon dioxide in bedding on the top cover of the mattress.

In another embodiment, the invention relates to a method of reducing the accumulation of carbon dioxide in bedding, comprising the steps of: forming a mattress having substantially nonporous bottom and side walls and a nonporous top cover having apertures at predetermined locations to allow the flow of air therethrough; and forcing air into an interior area of the mattress at a sufficient rate to percolate air through the top cover of the mattress.

In yet another embodiment, the invention relates to a mattress assembly having molded retaining means thereon, an inner core within the mattress assembly, a top cover and bedding attachable to the mattress foundation by the retaining means, and a fan in the mattress assembly for forcing fresh air through the mattress assembly.

These and various other advantages and features of novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the accompanying drawings and descriptive matter, which form a further part hereof, and in which there is illustrated and described a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings wherein like reference numerals indicate corresponding parts throughout the several views:

FIG. 1 is a perspective view of a preferred embodiment of a mattress assembly in accordance with the principles of the present invention disposed in a crib, an infant being illustrated as resting on the mattress assembly;

FIG. 2 is an exploded view of the mattress assembly shown in FIG. 1;

FIG. 3 is an enlarged partial sectional view illustrating air flow from the innerspring of the mattress assembly through the frame and bumper assembly and out the side walls of the frame and bumper assembly into the infant sleeping area;

FIG. 4 is a partial perspective view illustrating an embodiment of a latch mechanism for latching the frame assembly onto the sidewalls of the mattress assembly foundation;

FIG. 5 is a partial perspective view illustrating the frame assembly being pivoted into an open position whereby it is no longer resting on top of the sidewalls of the mattress assembly foundation;

FIG. 6 is a partial side view of fastener mechanism for fastening the bumper assembly onto the frame assembly;

FIG. 7 is a partial cross sectional view illustrating an embodiment of the fan assembly disposed in a sidewall of the mattress assembly foundation;

FIG. 8 is a planar view of a top cover of the mattress assembly;

FIG. 9 is an alternate embodiment of an apparatus for attaching the top surface of the mattress assembly and the mattress bedding onto the mattress foundation;

FIG. 10A is an exploded view of an alternate embodiment of the mattress assembly; and

FIGS. 10B and 10C are partial cross-section views illustrating alternative methods of fastening the mattress bedding.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings there is shown a preferred embodiment of a mattress assembly in accordance with the principles of the present invention, the mattress assembly being generally referred to by the reference numeral 30. The mattress assembly 30 is shown in FIG. 1 as being disposed in a conventional crib 32 with an infant 34 resting on the mattress assembly 30. It will be appreciated that the mattress assembly 30 might be used with or without a conventional crib 32 as shown.

Illustrated in FIG. 2 is an exploded view of the embodiment of the mattress assembly 30 shown in FIG. 1. The mattress assembly 30 shown includes a foundation 40, an innerspring 50, a top cover 60, mattress bedding 70, a frame assembly 80, and a bumper assembly 90.

The foundation 40 includes substantially nonporous side walls 41 and a bottom wall 42 so as to form an air impermeable foundation for the mattress. The walls 41,42 might be molded as a single piece from plastic or the like. Angle brackets 47 are shown disposed on the bottom wall 42 for centering the inner spring 50. These angle brackets 47 might be separate pieces or they might be integrally molded with the foundation 40.

As shown in FIGS. 1-2, 4 & 7, disposed in the side walls 41 is a fan assembly housing 43 housing a fan 49. As shown in FIG. 2, disposed on a top surface of the bottom wall is a heater 45. As shown in FIG. 7, in other embodiments, a heater might be present in the fan housing 43 as a heater coil 46 or the like.

The fan housing 43 will include suitable circuitry for controlling operation of the fan 49 and the heater 45/46. In the embodiment shown there are two switches 44a,b. Switch 44a is a master on off switch for the fan 49 and the heater 45/46 and switch 44b is for the heater 45/46 only.

As shown in FIGS. 2 and 3, the inner spring 50 is removably mounted in the mattress foundation 40. The inner spring 50 includes a plurality of coils 54 defining an open area for air flow. Air flow in the several views is generally illustrated by the arrows 56. In addition to or as opposed to the angle brackets 47, the mattress foundation 40 might further include individual guides or receptors (not shown) disposed on the bottom wall 42 for receiving each of the coils 54 to further assist in positioning of the inner spring 50. The inner spring 50 is preferably made of non-corrosive, washable material because of possible contact with saliva, sputum, urine, etc. A preferred material is galvanized spring steel.

As illustrated in FIG. 8, the top cover 60 is preferably made of a soft, nonporous material such as natural or synthetic rubber, vinyl, etc. so as to not harbor and provide a growth environment for bacteria or the like. Holes 61 are spaced preferably less than 2 cm apart, more preferably less than 1.5 cm apart, and most preferably on 1 cm staggered centers or less to insure that air is delivered from the innerspring 50 through the top cover 60 to at least one nostril of the infant. The diameter of the holes 61 must be large enough to prevent closing from lint, dust, etc. and yet small enough to build static pressure adequate to force air with sufficient velocity through the bedding. Over pressurizing will create air flow volumes that may cause hypothermia in infants. Under pressurizing will not have the desired effect on the bedding. Hole diameter should preferably be 3/16 inches when using fan volumes of 100 cubic feet per minute (cfm) to 170 cfm at static pressures of 0.04 inches H.sub.2 O to 0.08 inches H.sub.2 O and most preferably 1/8 inch diameter when used with total air flow of 25 cfm to 55 cfm at 0.01 inches H.sub.2 O to 0.05 inches H.sub.2 O static.

As illustrated in FIG. 2, the top cover 60 of the mattress includes apertures 62, such as eyelets or grommets, which are receivable on spaced apart projections 64 disposed on top of the side walls 41, whereby the top cover 60 is attached to the mattress foundation 40 in a taut condition. Likewise the bedding 70 is shown as including elasticized straps 72 about its periphery with apertures 74, such as eyelets or grommets, which are receivable on the projections 64, whereby the mattress bedding 70 is attached to the mattress foundation in a taut condition. In the embodiment shown, the projections are angled outward so as to facilitate retention of the top cover 60 and the bedding 70. In the preferred embodiment, the top cover 60 and the bedding 70 are taut when secured onto the projections 64. As can be seen the top cover 60 is readily removable to facilitate the cleaning of its top and bottom surfaces of saliva, sputum, urine, etc. that may collect on the top cover 60 or pass through the apertures 61 to the bottom surface of the top cover 60. The top cover 60 is simply removed or placed in position by sliding it off of and onto the projections 64.

It will be appreciated that other structures or methods might be utilized to removably mount and remove the top cover 60 without requiring tools. For example, as illustrated in FIG. 9, the top cover 60 and likewise the bedding 70, might include hooks 75 for engaging an overhanging portion 77 of the foundation 40 created by an indentation 73 disposed about the perimeter of the foundation 40 in the outside surface of the side walls 41. Preferably the hooks 75 of the bedding 70 and the top cover 60 would be spaced apart from one another so they do not overlap. This arrangement would allow the hooks 75 to be attached at any location about the perimeter of the foundation 40. Of course, in alternate embodiments tools might be required.

In the preferred embodiment, the mattress bedding 70 functions both as a mattress pad and sheet. Preferably the bedding 70 is of sufficient thickness to assure infant comfort yet be constructed of a material that when used in conjunction with the specified air flow and velocity prevents dangerous accumulations of carbon dioxide. A preferred embodiment shall be a coarsely woven, linen-like outer layer sandwiching a natural cotton batting interior devoid of resins or glues. In alternate embodiments, other porous materials might be used.

As noted above, the mattress bedding 70 is attached to the projections 64 on the foundation 40 and then the frame assembly 80 is disposed over the straps 72. The edges of the mattress bedding 70 might then be suitably attached to the frame assembly 80 and/or bumper assembly 90 by the use of straps of material 76 suitably secured to the bedding 70 which can be wrapped up and over the frame assembly 80 and/or the bumper assembly 90 and fastened thereto by VELCRO.TM. strips 93 or the like. In an alternate embodiment, the mattress bedding 70 might attach directly to the frame assembly 80 and/or the bumper assembly 90 so as to obviate the need to remove and replace the frame/bumper assembly when changing sheets.

The mattress foundation 40 preferably shall include rigid, impermeable, nonporous material such as plastic or wood. This will provide rigidity for keeping the top cover 60 and the mattress bedding 70 taut. As shown in FIGS. 2 and 7, it will provide a rigid compartment for installing the fan housing 43. The mattress foundation is preferably made of a material which is easily cleaned and resistant to harboring bacteria.

In the preferred embodiment, the innerspring 50 has a slightly smaller outer dimension than the inner dimension of the frame assembly 80 and is slightly higher so that when the frame assembly 80 and/or bumper assembly 90 is attached, the top cover 60 and the mattress bedding 70 are pulled down over the edges of the innerspring 50 thereby forming a slightly convex top surface.

The frame assembly 80 and the bumper assembly 90 might be a single assembly as opposed to two separate assemblies. The frame assembly 80 preferably has a height of 1.5 inches or less while the bumper assembly 90 preferably has a height of 4 to 6 inches. As shown in FIG. 3, both assemblies preferably comprise a rigid frame 81 and 91 respectively covered with a nonporous material 82 and 92, respectively, having a plurality of apertures in it. The configuration and arrangement of the apertures is preferably the same as that for the top cover 60.

As shown in FIG. 3, a bottom edge of the frame assembly 80 is preferably open to allow flow of air from the innerspring 50 through the top cover 60 and into a cavity in the frame assembly 80. The air will then pass out the apertures in the material 82 and into a cavity of the bumper assembly 90 where in turn the air will then pass out the apertures in the material 92 as generally illustrated by the arrows 56. The frame assembly 80 will provide a seal with the top surface of the mattress foundation to prevent air leakage out the sides of the mattress assembly. As shown in FIG. 3, the frame assembly 80 includes cavities 88 in alignment with and positionable over the projections 64 so as to allow the frame assembly 80 to form a seal with the mattress foundation 40.

As shown in FIGS. 4 and 5, mechanical latches 86 preferably requiring no tools, attach the frame assembly 80 to the mattress foundation 40 and allow the frame assembly 80 to be removed and/or pivoted upward as shown in FIG. 5. Latches 96, preferably requiring no tools, attach the bumper assembly 90 to the frame assembly 80. In the preferred embodiment the latches 96 can be moved laterally to avoid interference with crib pickets.

The fan assembly is preferably a modularized assembly for easy removal by hand and without the aid of tools. In this way, the mattress assembly 30 can be sold with or without the fan assembly. The fan assembly preferably can be readily added or replaced as needed. Preferably the fan assembly is compatible with future portable mattresses such as those used in bassinets or other types of portable playpens. As shown in FIG. 2, upon removal of the frame assembly 80 the fan housing 43 can be preferably slid into place without the aid of tools. The wall of the mattress foundation 40 is open at the top so as to allow the fan housing 43 to be inserted and removed through the top of the foundation wall. The off/on switches 44a,b shall be inaccessible to infants or made tamperproof to prevent inadvertent stoppage of the fan. Options could include controls recessed under a latching cover or "lock-lever" type switches.

The heater 45 is preferably non-adjustable to maintain fixed air temperature at the low end of the infant's thermoneutral range of 23-27 degrees Centigrade. This is important to prevent accidental overheating which is known to contribute to SIDS while also preventing hypothermia when using unconditioned room air. A preferred embodiment will include an integral fixed temperature thermostat.

Preferably an inlet of the fan 49 will include a media filter 53 to reduce the possibility of the top surface perforations plugging with lint or dirt. Standard finger guards shall be used on the inlet and outlet of the media filter 53. This arrangement will filter the air before it reaches the compartment where the fan is located.

Preferably the fan's electrical cord will have a tamperproof plug that fastens or locks securely to a wall outlet so as to prevent inadvertent stoppage of the fan 49. The tamperproof plug might also include a transformer to convert to low voltage AC or DC current.

FIG. 10A illustrates an exploded view of an alternative embodiment of the mattress assembly. The mattress foundation 140 is preferably molded as a single unit from tough-skinned, closed cell foam. A low voltage fan 149 is positioned in a sidewall of the mattress foundation 140, and has a child resistant switch 148 for operation thereof. Slot 145 in the side of the mattress foundation 140 opposite from the fan 149 is provided to conduct the electrical wire from the fan 149 to the "back" of the mattress. Molded hooks 154 are provided at corners and midpoints of the side sections of the mattress foundation 140 to retain portions of the bedding 170 and thus hold the bedding 170 taut across the mattress assembly. A slot 147 runs around the periphery of the mattress foundation 140, and may hold the cuff 174 of the bedding 170. Raised shoulders 144 may be provided on either side of the fan 149 to move the cuff 174 of the bedding 170 away from the intake of the fan 149, so as to avoid reducing the flow of air through the mattress assembly. The upper surface of the sidewalls of the mattress foundation 140 are provided with a plurality of fastener receptacles 152.

A mattress inner core 150, including a plurality of springs on a wire frame, preferably formed from non-corroding material or having a non-corrosive coating, thereon rests within the mattress foundation 140. The mattress foundation 140 may be provided with rails, stops, or angle brackets for locating the inner core 150 in a desired position within the mattress foundation, as described hereinabove.

The top cover 160 is positioned on top of the inner spring 150 and is preferably attached to the mattress foundation 140 by passing fasteners 162 through peripheral holes 165 which correspond to the fastener receptacles 152 in the mattress foundation 140. The top cover 160 is provided with a plurality of apertures 161 for allowing the free flow of air therethrough. The top cover 160 is preferably provided with cuttings 164 along either side in order to allow clearance for the attachment loops 172 of the bedding 170 be reach the hooks 154 positioned at mid-points along the side of the mattress foundation 140. The cuttings may also be used as handles to facilitate easy removal of the top cover 160 from the mattress foundation 140.

The bedding 170 is placed above the top cover 160. Attachment loops 172, preferably elasticized, are provided at the corners of the bedding 170 and midpoints along the sides thereof for looping over the hooks 154 of the mattress foundation 140 to attach the bedding 170 to the mattress assembly. The bedding 170 is preferably fabricated from a porous material to allow the passage of air therethrough. The bedding 170 is provided with a cuff 174 having elastic or a drawstring therein for attaching the bedding 170 to the bumper assembly 180 or the mattress foundation 140.

A free standing bumper assembly 180, preferably fabricated from the same type of material as the mattress assembly 140 may be provided to sit on top of the mattress foundation 140. Slits 182 in the corners of the bumper assembly 180 are provided to tuck the cuff 174 of the bedding 170 and so reduce bunching of the cuff 174 at the corners.

FIG. 10B illustrates a partial cross-section through the mattress assembly when the bumper pad 180 is in place. The cuff 174 of the bedding 170 is stretched over the top of the bedding 170 and held by the lip 184. Air passing up through the top cover 160 may travel up between the cuff 174 and the bumper assembly 180 and pass through the material of the cuff 174 in a direction inwards from the bumper assembly 180. This advantageously provides side ventilation without requiring that the bumper assembly 180 itself be ventilated. When the bumper assembly 180 is not in use, the cuff 174 of the bedding 170 may be inserted in the slot 147 on the periphery of the mattress foundation 140, as is illustrated in FIG. 10C. The embodiment illustrated in FIGS. 10A-10C may be readily taken disassembled to permit access to all components for cleaning or other maintenance.

Having read the foregoing description, it is to be understood, that even though numerous characteristics and advantages of various embodiments in accordance with the principles of the invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of the parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

Claims

1. A mattress assembly, comprising:

substantially nonporous bottom and side walls forming a mattress foundation;

a mattress inner core, having a frame structure including resilient support elements integral therewith, disposed in the mattress foundation as an integrally removable and insertable unit and being permeable to air;

a top cover of nonporous material covering the mattress inner core, the nonporous top cover having apertures at predetermined locations spaced apart by less than 2 cm to allow the flow of air therethrough,

releasable attachment mechanisms disposed to attach the top cover about its periphery to the side walls of the mattress foundation, and to permit repeated removal and reattachment of the top cover; and

a fan disposed with the mattress assembly for forcing air into the mattress inner core;

whereby the frame structure is readily removable as a unit for cleaning and the air is forced out the top cover so as to reduce the accumulation of carbon dioxide in bedding on the top cover.

2. A mattress assembly in accordance with claim 1, wherein the fan is disposed in the side wall of the mattress assembly.

3. A mattress assembly in accordance with claim 1, wherein the bottom and side walls are formed as an integrated, unitary plastic body.

4. A mattress assembly in accordance with claim 1, wherein the resilient support elements include coiled springs.

5. A mattress assembly in accordance with claim 1, wherein the inner core comprises corrosive resistant springs.

6. A mattress assembly in accordance with claim 1, further including hand holds for lifting the mattress.

7. A mattress assembly in accordance with claim 1, further comprising a handle on the top cover.

8. A mattress assembly in accordance with claim 1, wherein the attaching means comprises hooks on the side walls and the bedding comprises loop means for catching on the hooks.

9. A mattress assembly in accordance with claim 1, further comprising a bumper assembly disposed on the top cover, around a perimeter of the mattress assembly.

10. A mattress assembly in accordance with claim 8, further comprising a bumper assembly disposed on the top cover, around a perimeter of the mattress assembly, held in place by the bedding.

11. The mattress assembly of claim 1, further comprising guide means for positioning the inner core in a desired location within the mattress foundation.

12. A mattress assembly in accordance with claim 1, wherein the bedding includes a cuff fittable into a recess around the mattress assembly.

13. A mattress assembly in accordance with claim 1, wherein the top cover is removably attached to upper surfaces of the side walls.

14. A mattress assembly in accordance with claim 1, wherein the bottom wall of the mattress foundation includes centering guide members to center the mattress inner core.

15. A mattress assembly in accordance with claim 1, further comprising a heater to heat the air forced by the fan into the mattress inner core.

16. A mattress assembly in accordance with claim 1, wherein the apertures in the top cover have a dimension less than or equal to 3/16 inch.

17. A mattress assembly in accordance with claim 1, wherein the apertures have a diameter of around 1/8 inch and static pressure between the inner core and outside the mattress assembly is in the range between 0.01 inches and 0.05 inches H.sub.2 O.

18. A mattress assembly in accordance with claim 1, wherein the apertures have a diameter of around 3/16 inch and static pressure between the inner core and outside the mattress assembly is in the range between 0.04 inches and 0.08 inches H.sub.2 O.

19. A mattress assembly in accordance with claim 1, wherein the fan introduces air into the mattress foundation at a rate in the range between 25 and 100 cubic feet per minute.

20. A mattress assembly in accordance with claim 10, wherein the bumper assembly has a lipped portion around an outside perimeter thereof, and the bedding further comprises a cuff fittable into the lipped portion to hold the bumper assembly to the mattress assembly.

21. A mattress assembly in accordance with claim 1, wherein the side walls extend substantially to an upper surface of the mattress assembly.

22. A mattress assembly in accordance with claim 1, wherein the releasable attachment mechanisms include reusable fasteners.

23. A mattress assembly, comprising:

substantially nonporous bottom and side walls forming a mattress foundation;

a mattress inner core, having a frame structure including resilient support elements integral therewith, disposed in the mattress foundation as an integrally removable and insertable unit and defining an open area for the flow of air;

a top cover of nonporous material covering the mattress inner core, the top cover having apertures at predetermined locations to allow the flow of air therethrough, said top cover being removable to allow cleaning of the top and bottom surfaces;

attachment means for attaching the top cover about its periphery to the side walls of the mattress foundation, the attachment means being reusable so as to permit repeated removal and reattachment of the top cover;

means for attaching bedding to the mattress foundation for maintaining the bedding in a taut condition, said means including a plurality of retaining mechanisms provided on the side walls of the mattress foundation;

bedding attachable to the mattress assembly by attaching mechanisms operating co-operatively with respective retaining mechanisms of the mattress foundation; and

a fan disposed with the mattress assembly for forcing air into the mattress inner core whereby the air is forced out through the top cover.

24. The mattress assembly of claim 23, further comprising a bumper assembly positionable on top of the mattress foundation and held in place by the bedding.

25. The mattress assembly of claim 24, the bedding comprising a cuff portion around a perimeter thereof, and the bumper assembly comprising a lip around an outside surface, the cuff fittable into the lip so as to hold the bumper assembly to the mattress assembly.

26. The mattress assembly of claim 25, wherein the mattress assembly further comprises a recessed portion on outsides of the side walls, the cuff fittable into the recessed portion so as to partially cover the side walls with the bedding.

27. The mattress assembly of claim 23, wherein the top cover comprises a handle along a side thereof.

28. The mattress assembly of claim 27, further comprising a bumper assembly, positionable on top of the mattress foundation and bedding attachable to the mattress assembly by attaching mechanisms operating co-operatively with respective retaining mechanisms of the mattress foundation, the bedding being further attachable to the bumper assembly.

29. The mattress assembly of claim 28, wherein the bumper assembly has a lip around an outside surface and the bedding includes a cuff portion around a perimeter thereof, the cuff portion being fittable into the lip on the bumper assembly so as to hold the bumper assembly to the mattress assembly.

30. A crib assembly comprising:

a mattress including

substantially nonporous bottom and side walls forming a mattress foundation;

a mattress inner core, having a frame structure including resilient support elements integral therewith, disposed in the mattress foundation as an integrally removable and insertable unit and defining an open area for the flow of air;

a top cover of nonporous material covering the mattress inner core, the top cover having apertures at predetermined locations spaced apart by less than 2 cm to allow the flow of air therethrough, the top cover being removably attachable about its periphery to the mattress foundation to allow cleaning of the top and bottom surfaces;

releasable attachment mechanisms disposed to attach the top cover about its periphery to the side walls of the mattress foundation, and to permit repeated removal and reattachment of the top cover; and

a fan disposed with the mattress assembly for forcing air into the mattress inner core whereby the air is forced out through the top cover; and

a crib supporting the mattress.

31. The mattress assembly of claim 30, further comprising bedding attachable to the mattress assembly by attaching mechanisms operating co-operatively with respective retaining mechanisms of the mattress foundation.

32. A crib assembly in accordance with claim 30, wherein the releasable attachment mechanisms include reusable fasteners.

33. A method of reducing the accumulation of carbon dioxide in bedding, comprising:

forming a mattress having substantially nonporous bottom and side walls and a removable top cover which is nonporous except for apertures at predetermined locations to allow the flow of air therethrough;

disposing an integrated mattress inner core within the mattress, the inner core including a frame structure and resilient support elements integral therewith, and being integrally removable and insertable;

releasably attaching the top cover to the side walls of the mattress so as to maintain the top cover in position over the mattress and to permit repeated removal and replacement of the inner core; and

forcing air into an interior area of the mattress at a sufficient rate to percolate air through the top cover of the mattress.