Abstract:
An air inflatable mattress and mattress coverlet are provided for the prevention and treatment of decubitus ulcers (i.e., pressure sores or bedsores). The mattress incorporates a user selectable static or alternating air powered support surface for more uniformly redistributing pressure exerted on a patient&#39;s skin. The mattress coverlet encompasses a low air loss feature independent of the mattress&#39;s user selectable air powered support surface. Such low air loss feature provides a patient contact surface exhibiting a high moisture vapor transfer ratio in conjunction with a forced air flow to aid in reducing the moisture and heat near the patient&#39;s body. Both the mattress and mattress coverlet are driven by an external control system which houses the user controls, as well as the necessary pumps, regulators, and valving.

Description:
PRIORITY CLAIM 
       [0001]    This application is a divisional application of U.S. patent application Ser. No. 14/177,351 filed Feb. 11, 2014, which is a continuation application of U.S. patent application Ser. No. 11/809,079, filed May 31, 2007 (now abandoned), which is a divisional application of U.S. patent application Ser. No. 10/929,311 filed Aug. 30, 2004, which matured into U.S. Pat. No. 7,296,315 issued Nov. 20, 2007, and which is a continuation of U.S. patent application Ser. No. 09/907,954 filed Jul. 18, 2001 entitled “AIR-POWERED LOW INTERFACE PRESSURE SUPPORT SURFACE” which matured into U.S. Pat. No. 6,782,574 issued Aug. 31, 2004, which, in turn, claimed benefit of U.S. Provisional Application No. 60/219,074, filed Jul. 18, 2000, all of which are incorporated herein by reference for all purposes. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    This invention generally relates to mattresses and mattress coverlets for preventing, reducing, and/or treating decubitus ulcers, also known as pressure sores or bedsores. More particularly, this invention concerns therapeutic mattresses or mattress coverlets capable of transferring or dissipating moisture vapor and heat from a patient&#39;s skin. 
         [0003]    Often, patients that are bedridden or immobile can develop decubitus ulcers (pressure sores or bedsores). Such ulcers are often caused by pressure, friction, shear, moisture, and heat. Pressure results in a reduction of blood flow to the soft tissues of the body, particularly the skin. Continuous lack of blood flow, and the resultant lack of oxygen, can cause the skin to die and ulcers or sores to form. Friction and shear of the skin against the support surface can lead to skin tears and decubitus ulcers. Moisture and heat may lead to skin maceration. Other factors play a part in determining the speed with which such ulcers will form or heal including the overall health of the patient and such patient&#39;s nutritional status. 
         [0004]    To insure normal (or, at least, relatively improved) blood flow to such areas of potentially problematic contact, patients are often turned or repositioned regularly by medical personnel. Turning or repositioning of patients, however, is not always possible, particularly where trained medical staff are not available. Additionally, repositioning can be painful and disruptive for the patient. In an effort to overcome such difficulties, numerous mattresses and mattress coverlets have been developed to more evenly distribute, across the patient&#39;s skin, the pressure generated by the weight of the body. At least two methods have been used to redistribute skin pressure. The first is the use of static supports such as foam, air or water mattresses. The second method involves the use of alternating pressure inflatable mattresses or mattress coverlets that dynamically shift the location of support under the patient. Two examples of alternating pressure inflatable surfaces are illustrated in U.S. Pat. Nos. 5,509,155 and 5,926,884, the disclosures of which are fully incorporated herein by reference. 
         [0005]    In addition to such two methods of redistribution of skin pressure, an additional feature has been utilized to help address other of the aforementioned factors important to the healing process. In particular, a low air loss feature has been used to aid in the removal of both moisture vapor and heat thereby reducing both at the patient-bed boundary. This has been done in an effort to prevent skin maceration, keep wounds dry and to promote healing. 
         [0006]    There have been essentially three approaches to achieving a low air loss support surface. First, relatively tiny holes can be provided in the top surface of inflatable air cells of an air mattress having a vapor-permeable top surface. Such holes allow extra air to circulate inside the mattress to assist in drying moisture vapor passing through the top surface from the patient. 
         [0007]    Second, relatively tiny holes can be provided in the top surface of the mattress so that the air venting from the air cells can transfer through the top surface to the patient in order to remove both heat and moisture from the area immediately surrounding the patient. 
         [0008]    Finally, a multi-layer mattress coverlet can be used wherein the top layer is perforated to allow air flowing between the top layer and a middle vapor-permeable layer to exhaust across the patient thus aiding in removing both moisture and heat from the area immediately surrounding the patient. The third layer of such a three-layer approach may be a three-dimensional fabric, which allows for additional moisture vapor to be carried away from the patient. 
         [0009]    While each of these approaches is useful for its purpose, there are various disadvantages with these approaches and in particular, with using them individually. The first and second referenced approaches to obtaining a low air loss feature requires a large compressor pump to maintain sufficient air to inflate the air cells of the mattress. Such large compressor pumps tend to be very noisy, require high electrical consumption and generate significant heat in a relatively confined area. Such high electrical consumption, and the additional need for continuous blower operation, has, in the past, resulted in over-heating of the air used to circulate about the patient. Conversely, in the case of an elderly patient, airflow directly across their body could result in an uncomfortable reduction in body temperature or even a drying out of the skin beyond that which is helpful. 
         [0010]    Additionally, having holes in air cells of an inflatable air system results in a support surface that will deflate if there is a loss of electrical power or if no such power supply is available. Further, having perforations in the patient-bed contact surface results in a mattress that is not fluid-proof. This allows for potential contamination of the interior of such mattress by bodily fluids, products used to treat the patient and/or products used to clean such mattress itself. All three referenced approaches fail to allow air to flow under load (i.e., underneath the patient or through the top surface to the patient&#39;s skin when supporting the weight of the patient). 
         [0011]    Similarly, some prior art mattresses and mattress coverlets have had difficulty in controlling billowing. Billowing is the uncontrolled inflation of the upper surface of a mattress or mattress coverlet in the area immediately surrounding the outline of a patient&#39;s body when the patient lies on the mattress. In essence, the mattress or mattress coverlet fails to fully support a patient and instead seemingly envelops them when the patient&#39;s weight is applied thereto. Thus further illustrating the failure of some prior mattresses and/or mattress coverlets to fully support the patient and thus resulting in the air flow through the mattress, mattress top layer, or through the coverlet (i.e., the three aforementioned approaches) to flow around the patient, rather than flowing underneath the patient to aid in controlling moisture and heat. 
         [0012]    With all of the above approaches, it is further unknown to have the capability to turn on or off the low air loss option while retaining through the use of powered air cells the redistribution of skin pressure feature of the mattresses or mattress coverlets. If a low air loss therapy is not desired, a different system must be utilized with an alternative controller and air cell array. 
       SUMMARY OF THE INVENTION 
       [0013]    The present invention recognizes and addresses various of the foregoing limitations and drawbacks, and others, concerning the prevention and/or treatment of decubitus ulcers. It is, therefore, a principle object of the subject invention to provide an improved mattress and/or mattress coverlet for use in the prevention and treatment of decubitus ulcers. More particularly, it is a principle object of the subject invention to provide a mattress and/or mattress coverlet incorporating an air circulation system that does not exhaust its air directly across the patient. 
         [0014]    Another more particular object of the subject invention is to provide a new air flotation mattress and/or mattress coverlet including a low air loss feature. In such context, it is a further object to provide a mattress and/or mattress coverlet wherein the low air loss feature can be turned on or off as desired for the treatment of the patient, independently of how the basic patient support surface is operated. 
         [0015]    It is still a further object of the present invention to provide a mattress and/or mattress coverlet including a three-dimensional non-crush fabric to allow for the airflow of such a low air loss feature to flow under load. 
         [0016]    Another general object of the subject invention is to provide a mattress capable of selectively providing either an alternating pressure inflatable support or a floatation support for the redistribution of skin pressure. 
         [0017]    It is still a further object of the subject invention to provide a self contained external control system (ECS) including at least two pumps which are required to respectively maintain both the inflation of the mattress support and, if desired, the low air loss feature of the mattress coverlet. In such context, it is a further object of the present invention to provide a mattress or mattress coverlet capable of maintaining inflation of the patient support surface during a loss or unavailability of electrical power. 
         [0018]    Another object of the present invention is to provide an independently usable low air loss coverlet, which may be combined with various support scenarios, such as with preexisting mattress support systems, patient positioners, and/or wheelchair/seating cushions (as a retrofit or as original equipment combined with a prior design), regardless of whether such prior systems incorporate an air powered patient support surface. 
         [0019]    Additional objects and advantages of the invention are set forth in, or will be apparent to those with ordinary skill in the art from the detailed description herein. Also, it should be further appreciated that modifications and variation to the specifically illustrated, referenced, and discussed features, materials, or devices hereof may be practiced in various uses and embodiments of this invention without departing from the spirit and scope thereof, by virtue of present reference thereto. Such variations may include, but are not limited to, substitution of equivalent materials, means, or features for those shown, referenced or discussed, and the functional, operational, or positional reversal of various features, parts or the like. 
         [0020]    Still further, it is to be understood that different embodiments, as well as different presently preferred embodiments, of this invention may include various combinations or configurations of presently disclosed features, or elements, or their equivalents (including combinations of features or configurations thereof not expressly shown in the figures or stated in the detailed description). 
         [0021]    One exemplary embodiment of the present invention includes an air flotation mattress with an ECS. The support surface of such air flotation mattress may include a foam shell with a surface treatment on its upper surface. An exemplary GEO-MATT® surface treatment is illustrated in commonly owned U.S. Pat. No. 4,862,538, which is fully incorporated herein by reference. Such surface treatment aids in redistributing skin pressure. Additionally, the air floatation mattress includes a plurality of air cells running side-to-side providing the ability to sub-divide the mattress support into pre-designated zones. 
         [0022]    Included with such an exemplary air flotation mattress may be a low air loss coverlet in accordance with the subject invention. Such air flotation mattress serves as the primary support surface offering both a flotation and alternating pressure treatment option. Such low air loss coverlet provides an option to enhance the process of removing moist warm air from the area around the skin of the patient. It achieves such function by employing a patient-contact fabric top layer possessing a high moisture vapor transfer ratio enhanced by airflow through an inner layer of the coverlet. 
         [0023]    Such a mattress coverlet preferably comprises three layers. The first layer (on the top, facing the patient interface) is a vapor permeable layer, which allows moisture vapor and heat to travel away from the patient&#39;s body. Such moisture vapor enters the second layer, which may comprise a non-crush three-dimensional fabric, such as a specialty knit. The ECS forces air through the second (i.e., middle) layer to aid in carrying away the warm moist air. The final layer of such mattress coverlet (furthest from the patient interface) is a waterproof, vapor impermeable layer that acts as a boundary to protect the underlying mattress. 
         [0024]    The mattress coverlet&#39;s third layer may additionally comprise a coverlet-mattress topper such as a zippered sheath for encasing a mattress. Such construction advantageously enables the coverlet to effectively function with any mattress and not just the air flotation mattress as disclosed herein. Accordingly, various embodiments of the subject invention may comprise a mattress coverlet in accordance with the subject invention, combined with a variety of underlying patient support surfaces, including a mattress, patient positioner, and/or wheelchair/seating cushion (regardless of whether pre-existing, disclosed herewith, or later developed). 
         [0025]    Yet another exemplary embodiment of the present invention includes an air flotation mattress with an ECS. The air flotation mattress includes a plurality of air cells running head-to-foot. A foam shell topper with foam bolsters and foam sides running the length of the mattress on either side forms the air flotation mattress. At each end of the air flotation mattress and capping the foam bolsters and sides is either a foam header or foam footer, which along with the bolsters form a cavity in the mattress. This cavity is for positioning of the air cells. 
         [0026]    Included with such an exemplary air flotation mattress may be a low air loss coverlet in accordance with the subject invention. Such air flotation mattress serves as the primary patient support surface. Such low air loss coverlet provides an option to enhance the process of removing moist warm air from the area around the skin of the patient. It achieves such function by employing a patient-contact fabric top layer possessing a high moisture vapor transfer ratio enhanced by airflow through an inner layer of the coverlet. 
         [0027]    Such a mattress coverlet preferably comprises two layers. The first layer (on the top, facing the patient interface) is a vapor permeable layer, which allows moisture vapor and heat to travel away from the patient&#39;s body. Such moisture vapor enters the second layer, which may comprise a non-crush three-dimensional fabric. The ECS forces air through the second layer of such mattress coverlet to aid in carrying away the warm moist air. 
         [0028]    The air floatation mattress additionally comprises a multi-layer mattress topper comprising three layers. The first layer of such multi-layer mattress topper (adjacent such a mattress coverlet) is a waterproof, vapor impermeable layer that performs as a boundary to protect the underlying mattress. The second layer may comprise a non-crush three-dimensional fabric. The ECS forces air through the second (i.e., middle) layer in addition to providing airflow through the second layer of such a companion low air loss mattress coverlet. 
         [0029]    The multi-layer mattress topper&#39;s third layer may comprise a waterproof, vapor impermeable layer that performs as a boundary to protect the underlying mattress. The topper&#39;s third layer serves as the basis for a zippered sheath for encasing such a foam-based portion of the mattress. The multi-layer mattress topper&#39;s first and third layers are welded around their perimeter so as to secure their construction. 
         [0030]    Similarly, the two layers of such a coverlet are sewn together around their perimeter and may utilize an elasticized band there-around for securing the coverlet to the mattress. Such construction advantageously enables the coverlet to effectively function with any mattress and not just the air flotation mattress as disclosed herein. Accordingly, various embodiments of the subject invention may comprise a mattress coverlet in accordance with the subject invention, combined with a variety of underlying patient support surfaces, including a mattress, patient positioner, and/or wheelchair/seating cushion (regardless of whether pre-existing, disclosed herewith, or later developed). 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0031]    A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which: 
           [0032]      FIG. 1  is a bottom elevational view of an exemplary air flotation mattress in accordance with the subject invention with exemplary foam bolsters, sides, header, and footer, and individual air cell features of such exemplary mattress running side-to-side; 
           [0033]      FIG. 2  is a cross-sectional view of the exemplary air flotation mattress shown in  FIG. 1 , taken along line A-A in  FIG. 1 , illustrating an exemplary foam shell topper ( 20 ) with a specific surface treatment, a foam header and footer, and including a foam block with a hole there-through for connection of air passageways to the exemplary air cells of the mattress; 
           [0034]      FIG. 3  is a cross-sectional view of the exemplary air flotation mattress shown in  FIG. 1 , taken along line B-B in  FIG. 1 , illustrating the construction of an exemplary foam shell of the mattress including an exemplary foam shell topper ( 20 ), bolsters and sides. 
           [0035]      FIG. 4  is a top elevational view of the construction of an exemplary mattress coverlet showing numerous spot welds used in accordance with the subject invention to aid in the prevention of billowing, and showing exemplary air exhaust ports that provide an exit for the air flowing through the mattress coverlet during low air loss operation; 
           [0036]      FIG. 5  is a cross-sectional view of the exemplary air flotation mattress shown in  FIG. 1 , taken along line A-A in  FIG. 1 , showing an exemplary three-layer mattress coverlet in accordance with the subject invention and otherwise illustrating exemplary foam shell topper ( 20 ), header and footer, and air cells of the mattress; 
           [0037]      FIG. 6  is a schematic view of exemplary air flotation mattress air cell zones and the ECS which controls their inflation/deflation, and which in accordance with the subject invention separately provides for independent operation of the subject low air loss feature; 
           [0038]      FIG. 7  is a schematic view of an exemplary arrangement of air flotation mattress air cells and their respective inflation tubing; 
           [0039]      FIG. 8  is an exemplary internal schematic view of an ECS in accordance with the subject invention showing the two exemplary pumps used to respectively provide air for the air flotation mattress and the mattress coverlet, and showing an exemplary rotary valve which may be practiced in accordance with the subject invention; 
           [0040]      FIG. 9  is an external view of an exemplary ECS showing exemplary hanging hooks and rubber feet for supporting the ECS respectively on either the bedframe or the floor, as well as exemplary connection points for air flow passageways; 
           [0041]      FIG. 10  is a bottom elevational view of an exemplary air flotation mattress in accordance with the subject invention with exemplary foam bolsters, sides, header, and footer, and individual air cell features of such exemplary mattress running head-to-foot; and 
           [0042]      FIG. 11  is a cross-sectional view of the exemplary air flotation mattress shown in  FIG. 10 , taken along line C-C in  FIG. 10 , showing an exemplary multi-layer mattress coverlet and a multi-layer mattress topper in accordance with the subject invention and otherwise illustrating an exemplary foam shell topper ( 20 ), header and footer, and such head-to-foot air cells of the mattress 
       
    
    
       [0043]    Repeat use of reference characters throughout the present specification and appended drawings is intended to represent same or analogous features, aspects, or elements of the invention. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0044]    Reference will now be made in detail to a presently preferred embodiment of the invention, an example of which is discussed in conjunction with the accompanying drawings. Such example is provided by way of an explanation of the invention, not limitation thereof. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention, without departing from the spirit and scope thereof. For instance, features illustrated or described as part of one embodiment can be used on or in another embodiment to yield a still further embodiment. Still further, variations in selection of materials and/or characteristics may be practiced, to satisfy particular desired user criteria. Thus, it is intended that the present invention cover such modifications and variations as come within the scope of the present features and their equivalents. 
         [0045]    As referenced above, the present invention is particularly concerned with, in exemplary broad terms, an air flotation mattress  100  and mattress coverlet  200  for the prevention and treatment of decubitus ulcers (pressure sores and bedsores). The air flotation mattress  100  provides a user selectable flotation or alternating pressure support surface. The mattress coverlet  200  provides a low air loss feature that can be turned on or off as desired by the user (here, broadly referencing a patient or person resting on such coverlet and/or a caregiver therefore). 
         [0046]    As shown in the bottom elevational view of  FIG. 1 , the air flotation mattress  100  is formed by a foam shell topper  20  (best seen in  FIGS. 2 and 3 ) with foam bolsters  22  and foam sides  24  running the length of the mattress  100  on either side. At the respective ends of the air flotation mattress  100  and capping the foam bolsters and sides  22  and  24 , respectively, are a foam header  26  and foam footer  28 , which along with the bolsters  22  form a cavity in the mattress  100 . This cavity is for positioning of air cells, such as the exemplary grouped (i.e., zoned) air cells  30 ,  32 ,  34  and  36 . 
         [0047]    The cavity formed by the foam bolsters  22 , header  26 , and footer  28 , contains the air cells  30 ,  32 ,  34  and  34 . The air cells  30 ,  32 ,  34 , and  36  are essentially inflatable air bladders connected directly to an external control system  300  via passageways  76 ,  78 , and  80  (see  FIGS. 6 and 7  and corresponding discussion) for their inflation/deflation. Such air cells  30 ,  32 ,  34 , and  36  may be operated to provide the primary support surface for the patient. 
         [0048]    There are twelve exemplary air cells  30 ,  32 ,  34  and  36 . Other numbers thereof (or none at all) may be practiced in various embodiments of the subject invention. Such air cells  30 ,  32 ,  34 , and  36  are divided into four separate zones. The first exemplary zone (hereinafter the head zone) comprises three air cells  30  each of which may be maintained in an equal state of inflation/deflation relative to each other. The second exemplary zone (hereinafter the foot zone) comprises three air cells  36  each of which may be maintained in an equal state of inflation/deflation relative to each other. 
         [0049]    Exemplary zones three and four together (all of the remaining cells) comprise the central or torso zone. Each of zones three and four comprise an alternating set of three air cells  32  and  34 , respectively, within the torso zone. The torso zone (i.e., all six air cells  32  and  34 ) may be maintained at an equal state of inflation/deflation. As part of the capability of air flotation mattress  100  to provide alternating pressure support, zones three and four can alternate between specific states of inflation/deflation, thus dynamically changing the location of the support for the patient&#39;s torso. As part of the ECS  300 , a firmness control may be provided which allows the user to specify the level of inflation of the air cells  30 ,  32 ,  34 , and  36  both during the flotation and alternating pressure support treatment cycles. 
         [0050]    As represented to those of ordinary skill in the art by the cross-sectional view of  FIG. 2 , the foam shell topper  20  of such air flotation mattress  100  may have on its upper surface  38  a GEO-MATT® surface treatment to aid in redistributing skin pressure. The bottom surface  40  of such foam shell topper  20  may be cut to provide predetermined ridges  42  running side-to-side to act as retainers for such air flotation mattress respective air cells  30 ,  32 ,  34  and  36 . 
         [0051]    In order for the mechanical connections between the ECS  300  and both the mattress  100  and mattress coverlet  200  to be made an exemplary foam block  44  with a hole there-through may be located at the end of one foam bolster and side  22  and  24 , respectively. 
         [0052]    As best seen in the cross-sectional views of  FIGS. 2 and 3 , the foam shell topper  20  extends across almost the entire width and substantially the entire length of such mattress  100 . The foam shell topper&#39;s  20  width extends from each foam side  24 . Similarly, the topper&#39;s  20  length is terminated only by the foam header  26  and the foam footer  28 . The bolsters  22  act as both supports for the connection between the topper  20  and the sides  24  and as retainers for the air cells  30 ,  32 ,  34 , and  36 . 
         [0053]    The exemplary mattress coverlet  200  is comprised of three separate layers. As seen in  FIGS. 4 and 5 , the first layer  46  of such mattress coverlet  200  is a sheet of waterproof, vapor permeable material. It is designed to allow moisture-vapor and heat from the patient&#39;s body or relatively immediately adjacent thereto to pass through to the second (i.e., middle) layer  48 . The second layer  48  of such mattress coverlet  200  is a non-crush three-dimensional fabric that is moisture resistant and vapor and air permeable. It is through this middle layer  48  of the mattress coverlet  200  that the low air loss feature of the present invention forces air, which aids in removing the warm moist air generated by the patient. An exemplary depiction of the direction of airflow through the mattress coverlet  200  is indicated by exemplary airflow  50 . 
         [0054]    In accordance with the present preferred embodiment, the third layer  52  of the mattress coverlet  200  is a waterproof, vapor impermeable sheet. This final layer  52  acts as a retainer of the warm moist air generated by the patient and transmitted through the first layer  46  to the second layer  48 . It maintains the warm moist air within the second layer  48  so it can be removed by the low air loss airflow (as indicated in  FIG. 5  by exemplary air flow  50 ). Similarly, it acts as a boundary to prevent heat transfer from the air within the air flotation mattress&#39;s air cells  30 ,  32 ,  34 , and  36 , to the patient. Such third layer  52  may additionally comprise a zippered coverlet-mattress topper for encasing a mattress. 
         [0055]    In other embodiments, an exemplary coverlet  200  in accordance with the subject invention may be modularly applied to other supports including mattresses, wheelchair/seating cushions, and/or patient positioners (whether air powered, pre-existing, disclosed herewith, or later developed). Several exemplary such support surfaces can be found in commonly owned U.S. Pat. No. 5,568,660 to Raburn et al.; U.S. Pat. No. 5,797,155 to Maier et al.; and Des. 355,488 to Hargest et al., the disclosures of which are full incorporated herein by reference. 
         [0056]    Some former mattress coverlets have suffered from the problem of billowing. As further represented in the top elevational view of present  FIG. 4 , in accordance with the present invention the occurrence of billowing may be reduced through the use of spot welds  54  of the first layer  46  to the third layer  52  in locations throughout the surface of the mattress coverlet  200 . In making such spot-welds  54 , small sections of the material of the second layer  48  of the mattress coverlet  200  have been removed to allow for an unimpeded welding of the first and third layers ( 46  and  52 , respectively). 
         [0057]    The mattress coverlet  200  is preferably constructed of a first layer  46  comprising a polyurethane coated polyester which is perimeter welded  58  to the third layer  52 . Along the head end of the coverlet  200 , where the first and third layer  46  and  52 , respectively, are connected the perimeter weld  58  is intermittent to provide for exhaust air ports  60 . It is through these exhaust air ports  60  that the warm moist air trapped within the second layer  48  is disposed. 
         [0058]    The third layer  52  of the coverlet  200  preferably comprises a polyurethane coated nylon so as to be moisture and vapor impermeable. The second (i.e., middle) layer  48  is preferably a non-crush three-dimensional fabric. The third layer  52  additionally may have skirt welds  63  along substantially the entire perimeter of the material. 
         [0059]    As best seen in  FIG. 5 , in the presently preferred exemplary embodiment the third layer  52  forms a coverlet-mattress topper, which may encase a mattress. The coverlet-mattress topper comprises an upper (i.e., the third layer  52  of the mattress coverlet  200 ) and lower sheet connected to two side panels, a head panel, and a foot panel in a bag-like configuration. Around the perimeter of the coverlet-mattress topper, running along the middle of the side, head, and foot panels is a zipper  56  for encasing a mattress within the topper. It is this coverlet-mattress topper that may maintain the mattress coverlet  200  in place despite the movement of the patient while on the support surface. 
         [0060]    As will be clear to those of ordinary skill in the art from  FIGS. 6-9  and their associated discussion, the air flotation mattress  100  and the mattress coverlet  200  are regulated by the ECS  300 . The exemplary ECS  300  comprises two pumps  62  and  64 , a regulator  66 , a rotary valve  68 , a single quick-disconnect connector  70  for connection of air passageway  72  to the mattress coverlet  200 , and three quick-disconnect connectors  74  for connecting air passageways  76 ,  78 , and  80  to the air flotation mattress air cells  30 ,  32 ,  34 , and  36 . Air is provided to the head and foot zones via air passageway  76  and is provided to zones three and four (i.e., the central or torso zone) via air passageways  78  and  80 , respectively. The ECS features are preferably all within a stand-alone housing  82 . The housing  82  is provided with rubber feet  84  for positioning the housing on the floor and with hooks  86  for hanging the ECS  300  from a bedframe. 
         [0061]    The ECS  300  has two pumps  62  and  64  for separate operation of the air flotation mattress  100  and the mattress coverlet  200 . The first pump  62  operates the air flotation mattress  100 . It is preferably a pump which provides quiet operation and a quick response to an inflation request. The second pump  64  functions to provide air for the low air loss system in the mattress coverlet  200 . The low air loss system pump  64  is preferably a pump which provides a higher air flow rate for the mattress coverlet  200  than would be provided by the air flotation mattress pump  62 . 
         [0062]    The first pump  62  operates in connection with a regulator  66  and a rotary valve system  68  to provide air for the air flotation mattress  100 . In operation of this exemplary embodiment, the air provided to the head and foot zones (i.e., exemplary air cells  30  and  36 , respectively) is delivered through a first passageway  76 . This first passageway  76  serves to interconnect the head and foot zones to insure consistent inflation/deflation. The air provided to the torso zone, exemplary air cells  32  and  34 , respectively, enters through separate passageways  78  and  80 , respectively. With each of the passageways  78  and  80  associated with the torso zone are control valves  88  to either allow inflation/deflation or to maintain the current state of inflation/deflation of the air cells  32  and/or  34 . Such valves  88  are separately operable which allows for the provision of an alternating pressure support surface within the air flotation mattress  100 . When the control valves  88  within passageways  78  and  80  are set to mimic the inflation/deflation of the head and foot zones, the air flotation mattress  100  is able to provide a static support surface. The construction of such valves  88  and pumps  62  and  64  are well known to those of ordinary skill in the art, and details thereof form no particular part of the subject invention. 
         [0063]    The second pump  64  may be operated in accordance with the subject invention to provide a continuous flow of air to the low air loss mattress coverlet  200 . As shown in  FIG. 4 , the first layer  46  of the mattress coverlet  200  contains air exhaust ports  60  for the expulsion of the low air loss air flow through the mattress coverlet  200 . An air input port (not shown) is preferably generally located at the foot end of the mattress coverlet  200  and the air exhaust ports  60  are preferably located at the opposite end of the mattress coverlet  200 . However, one of ordinary skill in the art will recognize that alternative configurations of such features fall within the scope and spirit of the present invention. 
         [0064]    In operation, the ECS  300  functions to provide the user the widest variety of treatment options. The user can select from either a static pressure support surface, in which the air flotation mattress  100  maintains a consistent inflated state across all zones, or an alternating pressure support surface, in which the head and foot zones maintain a consistent inflation state and zones three and four within the torso zone dynamically fluctuate between opposed states of inflation/deflation, respectively. In addition to the choice of support surface function to be provided by the air flotation mattress  100 , the ECS  300  allows the user to choose whether or not to allow the operation of the low air loss mattress coverlet  200  to aid in removing warm moist air away from the patient&#39;s skin. It is this wide range of user (and/or caregiver) choice in treatment methods and its modularity that allows the system, the air flotation mattress  100 , the low air loss mattress coverlet  200  and the ECS  300 , to be so flexible. 
         [0065]    Additionally, in emergency operations, the system is designed to be as flexible as possible in order to aid in the treatment of the patient. Should the need arise to quickly provide a more sturdy surface for the patient, such as in the case where a patient suffers a heart attack and requires chest compression, the present invention provides the user three options: inflate the air flotation mattress  100  fully by utilizing the static support surface feature, terminate the operation of the pumps and allow the air flotation mattress to deflate, or to utilize the quick-disconnect connectors  74  between the ECS  300  and the air passageways  76 ,  78 , and  80  to allow for complete deflation of the air flotation mattress  100 . 
         [0066]    Similarly, when there is a loss of power to the ECS  300 , the system is designed to retain its functionality to aid in the treatment of the patient. The air flotation mattress is designed to maintain the inflation pressure within the air cells  30 ,  32 ,  34 , and  36 . It performs such function by allowing the pressure across all the cells  30 ,  32 ,  34 , and  36  to even out and become consistent (as when utilizing the static pressure support surface feature). The system is able to maintain the air within the cells through the use of several three-way control valves  88  which open to allow communication between the air cells  30 ,  32 ,  34 , and  36  and through the use of a two-way control valve  90  which closes to deny an exit path for the air already in the system. 
         [0067]    An alternative presently preferred embodiment may comprise an air flotation mattress  100  with a multi-layer mattress topper  400  and/or mattress coverlet  200  for the prevention and treatment, of decubitus ulcers (pressure sores and bedsores). The mattress coverlet  200  provides a low air loss feature that can be turned on or off as desired by the user (here, broadly referencing a patient or person resting on such coverlet and/or a caregiver therefor). 
         [0068]    As best seen in  FIG. 10 , a foam shell topper  20  with foam bolsters  22  and foam sides  24  running the length of the mattress  100  on either side forms the air flotation mattress  100 . At the respective ends of the air flotation mattress  100  and capping the foam bolsters and sides  22  and  24 , respectively, are a foam header  26  and foam footer  28 , which along with the bolsters  22  form a cavity in the mattress  100 . This cavity is for positioning of air cells  35 . Unlike the above-preferred embodiment, the air cells  35  of the presently preferred embodiment run head-to-foot with such cavity. 
         [0069]    As above, the cavity formed by the foam bolsters  22 , header  26 , and footer  28 , contains the air cells  35 . The air cells  35  are essentially inflatable air bladders connected directly to an external control system  300  as above described for their inflation/deflation. Such air cells  35  are operated to provide the primary support surface for the patient. 
         [0070]    As represented to those of ordinary skill in the art by the cross-sectional view of  FIG. 2 , the foam shell topper  20  of such air flotation mattress  100  may have on its upper surface  38  a GEO-MATT® surface treatment to aid in redistributing skin pressure. The bottom surface  40  of such foam shell topper  20  may be alternatively cut to provide predetermined ridges  42  running head-to-foot to act as retainers for such air flotation mattress&#39; respective air cells  35 . 
         [0071]    In accordance with this alternative presently preferred embodiment, the mattress coverlet  200  may be additionally sheathed in a multi-layer mattress topper  400 . The first layer  51  of the multi-layer mattress topper  400  is a waterproof, vapor impermeable sheet. The second (i.e., middle) layer  53  may comprise a non-crush three-dimensional fabric, such as a knit, cloth, polymeric film, foam or extruded woven fibers. Finally, the third layer  52  may additionally comprise a waterproof, vapor impermeable sheet for protection of the underlying mattress coverlet  200 . Such third layer  52  may additionally comprise a zippered sheath for encasing the mattress coverlet  200 . 
         [0072]    The exemplary mattress coverlet  200  is comprised of two separate layers. As seen in  FIG. 11 , the first layer  47  of such mattress coverlet  200  is a sheet of waterproof, vapor permeable material. It is designed to allow moisture-vapor and heat from the patient&#39;s body or relatively immediately adjacent thereto to pass through (such as perforations or relatively small holes  59  in layer  47 ) to the second layer  49 . The second layer  49  of such mattress coverlet  200  is a non-crush three-dimensional fabric that is moisture resistant and vapor and air permeable. It is through this middle layer  49  of the mattress coverlet  200  that the low air loss feature of the present invention forces air, which aids in removing the warm moist air generated by the patient. An exemplary depiction of the direction of airflow through the mattress coverlet  200  is indicated by exemplary airflow  50 . 
         [0073]    The two layers  47  and  49  of the mattress coverlet  200  are sewn together around their perimeter. Various methods of attaching such a coverlet  200  may be utilized. For example, said coverlet  200  may be formed with an elastic band sewn around its outer perimeter so as to envelop such a mattress  100  as would a fitted sheet. 
         [0074]    In the case of a “fitted-sheet” style coverlet  200 , the entirety, of the outer perimeter of the first and second layers  47  and  49 , respectively, may be sewn together. In such an embodiment, the forced air from the ECS  300  along with the warmth and moisture from the air in the second layer  49  of the coverlet may escape around the entire perimeter through the loose friction fit of the elastic band of the coverlet  200 . As described above, this alternative presently preferred embodiment may be regulated by an ECS  300 . The two pumps  62  and  64  of the ECS  300  serve to provide the airflow for both the primary patient support (i.e., the mattress  100  and the airflow through the middle layer  53  of the multi-layer mattress topper  400 ) and for the mattress coverlet  200 . The method of connection of the ECS  300 , its operation and features is as discussed in detail above. 
         [0075]    As in other embodiments, the exemplary coverlet  200  in accordance with the subject invention may be modularly applied to other supports including mattresses, wheelchair/seating cushions, and/or patient positioners (whether air powered, pre-existing, disclosed herewith, or later developed). 
         [0076]    It is to be understood that the present invention may be practiced in conjunction with combinations of additional features, not necessarily shown or discussed in detail. In particular, the size, shape and support characteristics of the air flotation mattress  100 , the multi-layer mattress topper  400  and/or the mattress coverlet  200  may vary as desired or as needed. Additionally, both the mattress coverlet  200  and the multi-layer mattress topper  400  may be utilized with mattresses of various size and shape (regardless of whether air powered, pre-existing, disclosed herewith, or later developed), in addition to being useful with other support devices such as patient positioner and wheelchair/seating cushions. All such variations, as would be understood by one ordinarily skilled in the art are intended to fall within the spirit and scope of the present invention. Likewise, the foregoing presently preferred embodiments are exemplary only, and their attendant descriptions are similarly intended to be examples of the present invention rather than words of limitation.