Abstract:
A two-mode therapeutic mattress system is provided, including a non-powered air mattress, a pressure dispersion cushion, and a selectively operable air diffusion coverlet in a common modular assembly for improved medical management of skin care. The non-powered air mattress includes longitudinal air cylinders providing a static air support system inflated to predetermined pressure. The longitudinal air cylinders are in pressure communication with elasticized reservoirs, in that the air level in the elasticized reservoirs dynamically reacts to changes in pressure in the longitudinal air cylinders, for example upon receipt of a patient upon the mattress system. The pressure dispersion cushion facilitates pressure relief with a number of lateral and longitudinal cuts resulting in a plurality of separate upright support cells, the size and construction of which may vary over the surface of the pressure dispersion cushion so as to provide selective support characteristics. The air diffusion coverlet contains a plurality of air pockets. The air diffusion coverlet operates in two modes: a “therapy mode” such that compressed air from an air compressor is pumped to the air diffusion coverlet, and an “off” mode in which the air pockets collapse to provide a suitable and relatively smooth bedding component to the therapeutic mattress system. The non-powered air mattress, pressure dispersion cushion, and selectively operable air diffusion coverlet cooperate to provide a single product that addresses localized pressure, maceration, shear stress, and dynamic changes in a patient&#39;s condition during the course of time.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims benefit of U.S. Provisional Application No. 60/512,882, filed Oct. 21, 2003. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     This invention concerns a therapeutic mattress system that may be operated in two modes. More specifically, this invention concerns a two-mode therapeutic mattress system including a non-powered air mattress, a pressure dispersion cushion, and a selectively operable air diffusion coverlet in a common modular assembly for improved medical management of skin care.  
         [0003]     Bedridden, non-ambulatory, or immobile patients are at increased risks for the development of breakdown of the integrity of the skin. Such breakdown may lead to the development of lesions, ulcers, sores, and the like. Such maladies may result in part from physiological causes such as decreased circulation, impaired nutrition, reduced skin thickness and viability, and other bodily weaknesses. However, external factors may also contribute to the development of such maladies. For example, localized pressure to the skin occurs from support of the patient&#39;s weight upon a bedding system. Because different portions of the human body have different weights, and have different surface areas for distribution of that weight upon a bedding system, different pressure can be brought to bear at various locations along the body. Localized points of relatively great pressure are particularly troublesome in the management of skin care and the prevention of skin ulcers. The dispersion specifically of localized points of greater pressure, and generally of the weight of the body, to as broad a surface area as possible is helpful in avoiding the development and/or progression of skin ulcers, and also to promote the healing of existing skin ulcers.  
         [0004]     Another external cause that may exacerbate the development of skin ulcers is maceration, a softening of the skin by soaking or steeping in moisture. As a person lies in a bed, perspiration from skin in contact with the bedding surface may tend to accumulate rather than evaporate, inasmuch as air circulation to the location of the accumulation is inhibited or limited by the very occurrence that caused the accumulation—skin in contact with the bedding surface. By remaining in contact with the skin, the moisture softens the skin and makes it more susceptible to breakdown, and thereby more susceptible to the development of skin ulcers. However, management of maceration across a spectrum of patients, even within a single facility such as a hospital or a nursing home, is not simple. While one particular patient may have a tendency for maceration, perhaps from an individual tendency to perspire more, a second particular individual may suffer from quite dry, frangible skin, perhaps from a tendency to perspire less. It would be useful for such a facility to have a uniform system, in part for the reduction of costs, that would nevertheless allow for selective employment or avoidance of modalities for the management of maceration, depending upon the particular needs of individual patients.  
         [0005]     Still a third external exacerbation of the tendency of the development of skin ulcers is shear stress upon the skin. Shear stress occurs, in part, from the friction of rubbing the surface of the skin. For the bed-bound person, shear most often occurs specifically between the person&#39;s skin and the bed linens upon the mattress. However, the degree and extent of that shear stress is influenced by the surface features of the mattress or padding beneath the bed linens. It is helpful in the management of skin care to employ bedding systems with technologies adapted for the reduction of shear between the skin of a patient and the bedding system.  
         [0006]     Healthcare costs are another factor that must be recognized for the management of skin care in the avoidance of skin ulcers. Skin ulcers, which potentially may lead to infections, bleeding, and secondary maladies and complications, increase the cost of care to the patient. At the same time, however, increased costs are associated with avoiding the development of such maladies and with treating existing ulcerations. For example, systems to address the exacerbation of localized pressure as a contributor to skin ulcers may not also address maceration as a factor; for a facility to warehouse both systems increases the cost to the facility for such services. Still further, a system for reducing shear stress to the skin may not be ideal for addressing either localized pressure or maceration, or both, and thereby increase costs still further. Furthermore, it must be recognized that the skills of the caregivers called upon to employ such systems may not be uniform such that simplicity in using any such system would be desirable as lowering the likelihood of mistake or misuse.  
         [0007]     It may be found also that, as any two patients may have varying needs, a particular individual patient may have needs that change over time, even during the course of a single day. For example, a particular patient may have a tendency toward perspiring during the afternoon hours, at the hottest part of the day, but toward dry skin, or even overly dry skin, during the evening and night hours. For such a patient, a system that is not adjustable to therapeutically address the perspiration during the afternoon hours so as to thereby reduce maceration, yet allow for normal perspiration or even externally-applied moisturizers and emollients during the evening, may tend to worsen rather than improve that particular patient&#39;s condition.  
         [0008]     It must also be recognized that patient care is far more expansive than simply providing for the prevention or improvement of skin sores. For example, patients may tend to move about upon the surface of a bed, including involuntary movements during sleep. Many bed systems have large metal rails or similar devices to prevent the patient from accidentally rolling out of the bed, but such barriers may prove awkward and obstructive otherwise, and may tend to provide psychological detriment to the patient. Furthermore, such systems interfere with entry upon and egress from the bed when needed.  
         [0009]     Higher localized pressures on the heels of a supine patient upon a bed are still another particular aspect of the interplay between the patient support surface and the development of pressure sores. The relatively excessive pressures focused on the heels are often difficult to reduce, in part simply from the configuration of the human anatomy—a supine patient upon a relatively flat bedding surface tends to generate higher localized pressure upon the heels.  
         [0010]     To combat the development of skin ulcers, the medical practice has employed the use of various mattress systems, including foam mattresses and air mattresses. However, while addressing particular causes of the development of skin ulcers, such products have not provided a solution in a single product that addresses localized pressure, maceration, shear stress, and dynamic changes in a patient&#39;s condition during the course of time.  
       SUMMARY  
       [0011]     In response to the discussed difficulties and problems, a new two-mode therapeutic mattress system has been discovered.  
         [0012]     According to the present invention, an integrated mattress system is provided that includes the combination of non-powered air mattress bladders, foam cushioning providing systematized pressure dispersion, and selectively operable low volume air diffusion to the skin of a patient reclined thereon, along with improved heel comfort and internal bolsters for prompting a patient away from the edges of the bed system.  
         [0013]     The present invention includes a mattress system adapted for fast, easy setup by caregivers. It includes a vapor permeable, yet fluid impermeable, exterior cover comprised of material easily cleaned, which may be bacteriostatically treated, may have antistatic construction and materials, may be treated with anti-fungal modalities, and may provide for flammability prevention or reduction.  
         [0014]     The present invention includes beneath the exterior cover an air diffusion coverlet. According to the invention, the air diffusion coverlet is constructed of air permeable material. Such material is formed into inflatable pockets about the surface of the air diffusion coverlet. Such pockets may be disposed about the entirety of the surface for acceptance of a patient thereon, or disposed only in preselected locations of the surface. The pockets are inflated by means of an external air compressor. The air compressor may be operable in therapy mode, such as to provide compressed air to the air diffusion coverlet. Alternatively, the air compressor may be selectively inoperable, such that compressed air is not provided to the air diffusion coverlet. In the first operation, with compressed air provided by the air compressor to the air diffusion coverlet, compressed air is provided to the inflatable pockets of the air diffusion coverlet. Under pressure, the compressed air is allowed to slowly escape from the inflatable pockets through small orifices in the pocket material, or through the weave of the material, or through the structure of nonwoven substrates; the compressed air is directed toward the patient upon the bed, thereby resulting in transfer or evaporation of any accumulated moisture as well as reduction of heat buildup. In the second operation, with the air compressor selectively turned off, no such air flow is provided to the patient via the air diffusion coverlet, but nevertheless the air diffusion coverlet need not be removed from the bedding system, as it provides a suitable and therapeutic component to the mattress system even in its non-powered mode.  
         [0015]     The present invention also includes a pressure dispersion cushion beneath the air diffusion coverlet. The pressure dispersion cushion may be formed of compressible material, such as polyurethane foam. The pressure dispersion cushion may include lateral cuts, from side to side, along its surface, of varying or constant depth, so as to create ribs in the pressure dispersion cushion. Such ribs would provide individually responsive support to the patient reclined upon the mattress system, allowing for reduction of localized pressure upon the skin of the patient. Additionally, the pressure dispersion cushion may include not only lateral cuts but also longitudinal cuts, perpendicular to the lateral cuts, upon its surface. Likewise, the longitudinal cuts may be of varying or uniform depth. So configured with lateral and longitudinal cuts, individual cells would be created, the cells being individually responsive to pressure from bearing the weight of a patient reclined upon the mattress system. About the perimeter of the pressure dispersion cushion, a bolster may also be provided in the present invention. The bolster, too, is comprised of compressible material, such as polyurethane foam, but is less compressible, and may be more dense, than the material used for the pressure dispersion cushion described here and above. As such, the perimeter bolster is firmer and would thereby gently prompt a patient reclined upon the bed away from the edges of the bed, without awkward obstructions from other devices, such as bed rails or gates, interfering with entry to and egress from the bed surface.  
         [0016]     The pressure dispersion cushion described hereinabove may also include a heel relief incline portion. The heel relief incline portion would reside in a plane slightly inclined as compared to the general plane of the other aspects of the pressure dispersion cushion. So configured, the heel relief incline would redistribute load from the heels of a patient reclined upon the bed to the calves, while providing complete foot support.  
         [0017]     Beneath the pressure dispersion cushion of the present invention lies a plurality of compressed air cylinders. The compressed air cylinders are comprised of a resilient substrate and lie longitudinally along the length of the therapeutic mattress system. The longitudinal air cylinders are inflated upon manufacture and sealed for permanent retention of the air held therein, thereby providing a static air system for permanent use in a therapeutic setting. So configured, the longitudinal air cylinders remain compressed during the life of the mattress system, and do not deflate during power outages or accidental disruption of electrical power to the mattress system. The longitudinal air cylinders are in pressure communication with one or more elasticized reservoirs disposed beneath the pressure dispersion cushion. The elasticized reservoirs may be partially enclosed within elastic sleeves, providing for compression of the air disposed within the reservoirs. In pressure communication with the longitudinal air cylinders, the elasticized reservoirs receive air displaced from the longitudinal air cylinders by the weight of a person upon the mattress system, thereby accommodating the load upon the bedding system and re-equalizing pressures. Furthermore, the air in the longitudinal air cylinders is injected to a predetermined pressure that, in cooperation with the elasticized reservoirs, prevent the longitudinal air cylinders from bottoming out upon receipt of the weight of a person upon the bed.  
         [0018]     Additional objects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned from practice of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]     The aspects described above, as well as other apparent aspects, advantages, and objectives of the present invention are apparent from the detailed description below in combination with the drawings, in which:  
         [0020]      FIG. 1  is a perspective view generally from the foot and right side of the mattress system, in partial cutaway, with sectional lines for reference in other figures;  
         [0021]      FIG. 2  is a perspective view generally from the foot and right side of the mattress system;  
         [0022]      FIG. 3  is a partial perspective view of the mattress system generally from the foot and right side, particularly showing the air diffusion coverlet;  
         [0023]      FIG. 4  is a partial perspective view of the mattress according to the present invention, generally from the foot of the system, particularly showing the air diffusion coverlet folded back to reveal the pressure dispersion cushion;  
         [0024]      FIG. 5  is a partial perspective view of the mattress system according to the present invention, generally from the foot and right side of the system, particularly showing the air diffusion coverlet and pressure dispersion cushion removed to reveal the longitudinal air cylinders, elasticized reservoirs, and other components;  
         [0025]      FIG. 6  is a partial perspective exploded view, showing portions of the pressure dispersion cushion, longitudinal air cylinders, and elasticized reservoirs, along with other components;  
         [0026]      FIG. 7A  is a cross-sectional view, taken along line A-A in  FIG. 1 , illustrating a first exemplary air diffusion coverlet, pressure dispersion cushion, longitudinal air cylinder, and elasticized reservoirs;  
         [0027]      FIG. 7B  is a cross-sectional view, taken along line A-A in  FIG. 1 , illustrating a second exemplary air diffusion coverlet, pressure dispersion cushion, longitudinal air cylinder, and elasticized reservoirs;  
         [0028]      FIG. 8  is a cross-sectional view, taken along line B-B in  FIG. 2 , illustrating an exemplary air diffusion coverlet, pressure dispersion cushion, and longitudinal air cylinder;  
         [0029]      FIG. 9  is a cross-sectional view, taken along line A-A in  FIG. 1 , showing in dashed lines a diagrammatic of a patient disposed upon the mattress system; and  
         [0030]      FIG. 10  is an isolated, enlarged side elevational view of a sloping heel pressure relief section in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0031]     Reference will now be made in detail to the presently preferred embodiments of the invention, one or more examples which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not by way of limitation of the invention. For example, features illustrated or described as part of one embodiment may be used on another embodiment to yield a still third embodiment. It is intended that the present application include such modifications and variations as come within the scope and spirit of the invention. The same numerals are used to refer to the same features throughout the drawings and the text that follows.  
         [0032]     As shown in  FIG. 1 , the therapeutic mattress system generally  20  includes an air diffusion coverlet  30  atop a pressure dispersion cushion  50 , which in turn is atop longitudinal air cylinders  70 , configured to provide the widest array of treatment options available at commercially reasonable prices.  FIG. 1  is a perspective view, in partial cutaway, showing the relative locations of each of these three component subsystems. The therapeutic mattress system  20  generally would be used with a hospital-type bed, shown in dash lines in  FIG. 1 , but may be used on any suitable platform and its therapeutic advantages may be realized independent of the type of specific platform employed.  
         [0033]     As shown in  FIG. 2 , the therapeutic mattress system  20  typically would be enclosed within a vapor permeable exterior fitted cover  22 . Also as depicted in  FIG. 2 , an air compressor  85  is used to provide compressed air to the air diffusion coverlet by means of an air hose  87 .  
         [0034]      FIG. 3  depicts the therapeutic mattress system  20  with the exterior fitted cover  22  folded back to reveal the air diffusion coverlet  30 . As depicted in  FIG. 3 , the air diffusion coverlet  30  is in “therapy mode” such that compressed air from the air compressor  85  is being pumped to the air diffusion coverlet  30 , inflating the inflatable pockets  35 .  
         [0035]      FIG. 4  is a partial perspective view of the therapeutic mattress system  20  showing the air diffusion coverlet  30  folded back to reveal the pressure dispersion cushion  50 . As will be described in greater detail hereinbelow, the pressure dispersion cushion  50  is comprised of compressible foam, such as polyurethane foam. However, various subcomponents of the pressure dispersion cushion  50  may be made from foams of differing compressabilities, for advantageous reasons.  
         [0036]      FIG. 5  is a perspective view of the therapeutic mattress system  20  with the air diffusion coverlet  30  and the pressure dispersion cushion  50  removed, with the longitudinal air cylinders  70  and elasticized reservoirs  73  revealed. As depicted in  FIG. 5 , the longitudinal air cylinders  70  are disposed lengthwise along the therapeutic mattress system  20 . In the exemplary embodiment depicted in  FIG. 5 , the elasticized reservoirs  73  are disposed toward the foot of the therapeutic mattress system  20 .  
         [0037]      FIG. 6  is a partial perspective exploded view showing portions of the pressure dispersion cushion  50 , the longitudinal air cylinders  70 , the elasticized reservoirs  73 , and the air lines  76  that provide pressure communication between the elasticized reservoir  73  and the longitudinal air cylinders  70 . Also depicted in  FIG. 6  is a portion of the pressure dispersion cushion  50 .  
         [0038]      FIG. 7A  is a cross-sectional view illustrating a first exemplary air diffusion coverlet  30 , pressure dispersion cushion  50 , longitudinal air cylinders  70 , and elasticized reservoirs  73 . As depicted in  FIG. 7A , the inflatable pockets  35  of the air diffusion coverlet  30  may be lateral relative to the orientation of the therapeutic mattress  20 , or may be individual pockets as explained in more detail herein below.  
         [0039]      FIG. 7B  is a cross-sectional view illustrating a second exemplary embodiment of the therapeutic mattress system  20 , in which the inflatable pockets  35  of the air diffusion coverlet  30  are longitudinal along the length of the therapeutic mattress system  20 .  
         [0040]      FIG. 8  is a cross-sectional view illustrating an exemplary air diffusion coverlet  30 , pressure dispersion cushion  50 , and longitudinal air cylinders  70 .  FIG. 8  also depicts the perimeter bolsters  58  along the lateral sides of the pressure dispersion cushion  50 ; the pressure dispersion cushion  50  is represented by crosshatching of a given direction, whereas the perimeter bolsters  58  are represented by crosshatching of a different orientation.  
         [0041]      FIG. 9  is a cross-sectional view showing in dashed lines a diagrammatic representation of a patient  95  disposed upon the therapeutic mattress  20 , received upon the inflatable pockets  35  of the air diffusion coverlet  30 . As depicted in  FIG. 9 , the air diffusion coverlet  30 , the pressure dispersion cushion  50 , and the longitudinal air cylinders  70  conform under the weight of a patient  95  to the shape of the patient  95  disposed upon the therapeutic mattress  20 .  
         [0042]     Finally,  FIG. 10  is an enlarged side elevational view of an isolated portion of the pressure dispersion cushion  50 , showing the heel relief incline  64  for redistributing pressure from the heels of the patient  95  to the patient&#39;s calves.  
         [0043]     In greater detail, it may be understood that the exterior fitted cover  22  may comprise various fabrics, such as a stretch fabric of different materials. Such fabric may be provided with other technological features, for example treated so as to be easily cleaned. Furthermore, the exterior fitted cover  22  may be treated with bacteriostatic agents, anti-static agents, anti-fungal agents, and flame retardants. The exterior fitted cover  22  is vapor permeable, so as to allow diffusion of compressed air from the inflatable pockets  35  of the air diffusion coverlet  30  to reach the patient  95  so as to provide evaporation of accumulated moisture and dissipation of built-up heat. Cover  22  comprises material that, though vapor permeable, is fluid impermeable, or at least largely fluid resistant, such that perspiration and/or accidental bodily waste upon the therapeutic mattress system  20  will not penetrate through the cover  22  so as to reach the air diffusion coverlet  30 . Such fluid impermeability or resistance may be realized by any number of known commercial means, including weaving techniques and surface treatments.  
         [0044]     The air diffusion coverlet  30  likewise comprises fabric, either woven or nonwoven, providing for air permeability. Such air permeability may be realized through the relative tightness of the weave of woven fabric, the relative interconnectedness of the fibers of nonwoven fabric, or even by the mechanical perforation of the fabric to create small holes there through. The air diffusion coverlet  30  receives compressed air from the air compressor  85  via an air hose  87 . The air diffusion coverlet  30  is a “low air loss” system, meaning that compressed air within the inflatable pockets  35  escapes the inflatable pockets  35  slowly so as to provide gentle, non-disruptive air flow to the skin of the patient  95 .  
         [0045]     The air diffusion coverlet  30  may have inflatable pockets  35  of various configurations. As illustrated in  FIGS. 1 and 3 , the inflatable pockets  35  may be configured to be relatively smaller individual, rectangular pockets, such that individual pockets may be observed not only laterally across the therapeutic mattress system  20 , but also longitudinally so as to create a grid of such inflatable pockets  35  upon the air diffusion coverlet  30 . Alternatively, and as illustrated in  FIG. 7B , the inflatable pockets  35  may be longitudinal members of a longitudinal length approximating that of the therapeutic mattress system  20 . In either event, the inflatable pockets  35  are in air communication with one another, such that compressed air from the air compressor  85  will be transferred from one inflatable pocket  35  to another, such that, once the pressure from the air compressor  85  within the air diffusion coverlet  30  reaches equilibrium, each inflatable pocket  35  will have substantially the same internal positive pressure of air compressed therein. It is to be understood that the air diffusion coverlet  30  includes at least two layers of substrate, with the inflatable pockets  35  defined between the two substrates; the inflatable pockets  35  may be formed by selective gluing, heat welding, stitching, or the like between the two layers of substrate to form the inflatable pockets  35 . Regardless of the method of construction, provision is made for air communication between and amongst the inflatable pockets  35  by predetermined locations of no gluing, no heat welding, no stitching, or the like so as to create vapor pathways between the inflatable pockets  35 .  
         [0046]     It is also to be understood that the billow of the inflatable pockets  35  shown in the Figures is depicted for illustration purposes only. Different sized inflatable pockets  35  may be practiced, including particularly different dimensions of the internal chambers  36  of the inflatable pockets  35 , with different amounts of billowing of the individual inflatable pockets  35 .  
         [0047]     The air compressor  85  provides compressed air to the air diffusion coverlet  30  via the air hose  87 . The air hose  87  connects with the air diffusion coverlet  30  by any of a number of conventional means already known in commerce, all of which are intended to be quick and uncomplicated. As such, the air compressor  85  and the air hose  87  may be brought to a particular therapeutic mattress system  20  and connected simply, with minimal disruption to the patient  95  received upon the mattress system  20 . The air compressor  85  is selectively operable between a “therapy mode” in which it provides compressed air to the air diffusion coverlet  30 , and an off mode in which no such air is provided. When the air compressor  85  is in off mode, the internal chambers  36  of the air diffusion coverlet  30  contain no compressed air, and collapse to provide a suitable and relatively smooth bedding component to the therapeutic mattress system  20 . When the air compressor  85  is in therapy mode, the flow rate of air from the compressor  85  to the air diffusion coverlet  30  via the air hose  87  may be varied, either by valving or by adjusting the speed of operation of the air compressor  85 . In such way, the therapeutic effect of the air diffusion coverlet may be regulated for individual patient needs. In another embodiment, the air flow from the air compressor  85  to the air diffusion coverlet  30  may be cooled or heated, as might be medically advantageous in particular treatment cases. Still further, the composition of the air flow to the air diffusion coverlet  30  may be modified, such that air compressor  85  provides humidified air to the air diffusion coverlet  30 , or provides air impregnated with medicinal agents such as topical antibiotics, emollients, fragrances, decongestants, or antiseptics; such agents may be introduced into such air flow at the air compressor  85 , or along the length of the air hose  87 .  
         [0048]     The pressure dispersion cushion  50  may include a variety of constructions designed and intended to facilitate pressure relief. Pressure relief, for example, may be provided by a number of lateral cuts  54  formed in such surface, along with a number of longitudinal cuts  52  that may also optionally be provided. Such lateral and longitudinal cuts  54 ,  52  may be practiced in any of the embodiments herewith, although for clarity they are represented only in  FIGS. 1 and 4 . The combination of lateral cuts  54  and longitudinal cuts  52  results in a plurality of separate upright support cells  56 , the size and construction of which may vary over the surface of the pressure dispersion cushion  50  so as to provide selective support characteristics. Examples of such various arrangements as may be practiced in combination with the subject invention are discussed in commonly owned U.S. Pat. Nos. 4,862,538; 5,025,519; 5,252,278; 5,580,504, the complete disclosures of which are fully incorporated herein by reference. It should be understood that the appended Figures, for example  FIG. 8 , depict a thickness of pressure dispersion cushion  50  relative to a thickness of longitudinal air cylinders  70  for illustration purposes only. Pressure dispersion cushion  50  may have any advantageous thickness relative to the thickness of longitudinal air cylinders  70 , for example less than one-half, as may be found therapeutically beneficial in individual circumstances.  
         [0049]     As depicted, for example, in  FIG. 4 , the pressure dispersion cushion  50  also includes perimeter bolsters  58 . The perimeter bolsters  58  are fabricated of compressible material, but are less compressible than the pressure dispersion cushion  50 . It is understood in the art that various nomenclatures may describe support characteristics of given mixtures of compressible foam. For example, “IFD” is intended to refer to the known characteristic of so-called indentation force deflection. Indentation force deflection (IFD) may be defined as the number of pounds of pressure needed to compress a fifty square inch circular plate into a pad of a given percentage deflection thereof. For example, a 25% IFD of 30 lbs. would mean that 30 lbs. of pressure is required to push a 50 square inch circular plate into a 4″ pad a distance of 1″ (that is, 25% of the original, unloaded thickness). Using a 25% IFD characteristic for description purposes, the perimeter bolsters  58  may exhibit a 50-58 lb. IFD, for example 54 pounds, while the pressure dispersion cushion  50  may exhibit an IFD of less than 44 pounds, for example, 35 pounds. So configured, the mattress system  20  provides a number of features that maintains a stable support environment for a patient ingressing to egressing from the mattress system  20 . The resulting structure and practice of the invention results in roll protection, such that a patient might detect, consciously or subconsciously, the greater density of the perimeter bolsters  58  about the perimeter of the mattress system  20  and thereby be prompted away from the edge of the mattress system  20 . Additionally, the system provides safer patient entry upon an egress from the mattress system  20  by providing a more solid, less compressible boundary around the outer dimensions of the mattress system  20 .  
         [0050]     As depicted in the exemplary embodiment shown in  FIG. 6 , the bottom surface of pressure dispersion cushion  50  may alternatively be cut to provide predetermined ridges  51  to act as retainers for the longitudinal air cylinders  70 , providing inter-locking between the two subsystems and thereby improving structural integrity.  
         [0051]     As depicted in  FIG. 10 , the therapeutic mattress system  20  may also include a heel relief incline  64 . The heel relief incline  64  is a sloping heel pressure relief section for redistributing load from relatively less tolerant heel areas of a patient reclined upon mattress system  20  to relatively more pressure-tolerant lower legs and calves. At the heel relief incline  64 , an overall angular slope is introduced to a portion of the pressure dispersion cushion  50 , as represented by an angle generally  66 . The heel relief incline  64  may practice various ranges of angle  66 , such as for example 6 degrees, to achieve improved patient heel health in different situations. As represented in  FIG. 10 , the sloping portion of the heel relief incline  64  is primarily achieved by reduction in the size and/or shape of the respective cells  56 . In such way, a minimum base thickness of the pressure dispersion cushion  50  is maintained, despite the angled surface for the heel relief incline  64 .  
         [0052]     As depicted in  FIGS. 1 and 6 , among others, beneath the pressure dispersion cushion  50  of the mattress system  20  lie longitudinal air cylinders  70 . Together with the elasticized reservoirs  73 , the longitudinal air cylinders represent a static air support system inflated to predetermined pressure at manufacture, for example 0.10 pounds per square inch, to suit original manufacturing specifications. Different numbers and sizes of the longitudinal air cylinders  70  may be practiced, for example four. Additionally, different numbers and sizes of the elasticized reservoirs  73  may be practiced, for example two. The longitudinal air cylinders  70  are in pressure communication with the elasticized reservoirs  73  by the air lines  76  connecting there between. The longitudinal air cylinders  70  are integrally formed from polymeric film. Moreover, the longitudinal air cylinders  70  are independent of one another, reacting independently to patient movement upon the mattress system  20 . While the exemplary embodiment shown in  FIGS. 1 and 6  are longitudinal cylinders, it will be appreciated that laterally-positioned air cylinders may also be practiced within variations of this invention.  
         [0053]     The elasticized reservoirs  73  are resiliently actuated, in that the air level in the elasticized reservoir  73  dynamically reacts to changes in pressure in the longitudinal air cylinder  70 . For example, upon receipt of a patient upon the mattress system  20 , air will be displaced from the longitudinal air cylinders  70  into one or more of the respectively connected elasticized reservoirs  73  through the air lines  76 . However, because of the predetermined pressures and elasticities of the longitudinal air cylinders  70  and the elasticized reservoirs  73 , and because the elasticized reservoirs  73  each include an annular elastic sleeve  73 , all of the air within a particular longitudinal air cylinder  70  will not be displaced. Instead, the pressure level between the longitudinal air cylinder  70  and its inner connected elasticized reservoir  73  will reach a pressure equilibrium that provides residual support to the patient.  
         [0054]     So configured, it will be appreciated that the subcomponent system of the longitudinal air cylinders  70 , elasticized reservoir  73 , and annular elastic sleeve  74  function to redistribute air from the longitudinal air cylinders  70  to the elasticized reservoirs  73  to accommodate load upon the mattress system  20  re-equalized pressures within the system, and support the patient accepted upon the mattress system  20  without bottoming out. Opposing longitudinal elements  60 , in concert with the ridges  51 , retain the longitudinal air cylinders  70  in proper position.  
         [0055]     Various modifications and variations can be made in the embodiments of the present invention without departing from the scope and spirit of the invention. It is intended that the present invention include such modifications as come within the scope of the within disclosure, and their equivalents.