Abstract:
A therapeutic mattress for bed ridden patients comprises a plurality of inflatable tubular elements fabricated from a low air loss material which are disposed in side by side, transverse relationship to a mattress supporting surface. The air pressure within the various tubular elements is cyclically varied to produce a wave-like deformation of the patient supporting surfaces of the tubular elements which progresses longitudinally along a selected portion of the length of the mattress.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a mattress for supporting bedridden patients in a manner that helps prevent and treat complications of immobility such as skin breakdown and decubitus ulcers. More particularly, this relates to a patient supporting mattress overlay or other support employing a plurality of transverse inflatable tubular elements sequentially inflated and deflated to provide a therapeutic wave beneath the patient. 
     2. Background Art 
     It has long been known that bedridden patients may be spared the discomfort of bed sores and other complications by providing frequent changes and periodic reductions in the pressure points of the patient supporting mattress against the patient&#39;s body. A number of prior patents disclose patient supporting mattresses formed by a plurality of inflatable bag or sack elements formed from a low loss air material. See for example, U.S. Pat. No. 5,003,654 wherein a plurality of inflatable sacks, having a complex top surface configuration when inflated, are disposed in side by side transverse relationship on a mattress supporting surface of a hospital bed. When alternate sacks are inflated, accompanied by current deflation of the intermediate sacks, the patient is moved with a rolling motion from a position wherein one side of the patient&#39;s body is supporting most of the weight of the body, to an alternate position wherein the other side of the patient&#39;s body provides the primary support. While this mattress arrangement is very effective in eliminating bed sores, the complexity of the transversely disposed, inflatable bag elements makes the total mattress more costly than desired. 
     There is a need, therefore, for a therapeutic mattress employing a plurality of transversely disposed inflatable elements which are capable of producing a desired movement of the mattress supporting points relative to the patient&#39;s body, and which can be manufactured at a cost substantially less than that of prior art constructions. 
     SUMMARY OF THE INVENTION 
     This invention provides a therapeutic mattress for prevention of bed sores on bed ridden patients, comprising a plurality of simple tubular inflatable elements formed of a low air loss material. The inflatable tubular elements are mounted in transverse, side by side relationship on the top of a generally rectangular foam pad whose dimensions conform to that of the mattress supporting surface of the hospital bed. The foam pad has an upstanding wall of fabric perimetrically secured to its edges. The inflatable tubular elements are disposed within the confines of the upstanding wall, extending transversely across the entire pad surface and lying in side by side relationship to cover the full length of the underlying foam pad mattress base. Detachable connectors are provided between the ends of the inflatable tubular elements and the upstanding wall. 
     A box-like housing is provided which may be conveniently hung on the footboard of the bed and which contains an electric motor driven pump for producing an output of pressured air. The pressured air is directed to a manifold wherein it is divided into a plurality of streams, preferably three. The three streams of pressured air are then directed through three electrically variable, pressure reducing valves and the outputs of such valves are respectively connected to three flexible primary conduits which pass along one side of the array of inflatable elements, being disposed intermediate the ends of the elements and the upstanding retaining wall and, if desired, restrained by the detachable connectors. 
     Each conduit supplies fluid pressure to a group of longitudinally spaced inflatable tubular elements. In a preferred embodiment of the invention, the first tubular inflatable element adjacent the footboard, the fourth tubular inflatable element from the footboard, the seventh, etc. are interconnected by flexible secondary conduits and connected to one of the three primary conduits supplying pressured air. The second primary pressured air conduit is connected to the second, fifth, eighth, etc. inflatable tubular element, while the third primary pressured air conduit is connected to the third, sixth, ninth, etc. inflatable tubular element spaced from the footboard. In other words, groups of longitudinally spaced, inflatable tubular elements are respectively supplied with a variable air pressure from the air pressure controlling valves, preferably in a manner that produces a wave-like progression beneath the patient. The resulting waves rythmically massage the patient&#39;s skin to further stimulate blood circulation and oxygenation in the skin. 
     As previously mentioned, each of the air pressure controlling valves are electrically operated, as by a small motor, and an appropriate electrical control circuit permits the sequential actuation of such valves so that the pressure in each group of longitudinally spaced, inflatable tubular elements may be sequentially and cyclically increased and decreased. The net result of such sequential pressure cycling is to cause the upper or patient supporting surface of each tubular element to slightly raise and lower in sequence, resulting in a wave of movement of the patient supporting surface that progresses from the foot of the bed to the head of the bed or vice versa. Such wave action may be continuous or intermittent, depending on the manual setting of the control circuit. The actual amount of pressure increase or decrease is preferably kept at a minimum because all that is desired, for elimination of bed sores, is a periodic reduction in the amount of pressure exerted on each part of the patient&#39;s body which is supported by the inflatable tubular elements. It is also thought that sequential pressure fluctuations create a therapeutic wave which rythmically massages the patient to stimulate circulation. 
     A therapeutic mattress embodying this invention will obviously be much less costly to manufacture than the aforementioned prior art mattresses and yet will produce equally efficient results in minimizing the occurrence of bed sores on a bed ridden patient. 
     Further objects and advantages of the invention will be readily apparent to those skilled in the art from the following detailed description, taken in conjunction with the annexed sheets of drawings, on which is shown a preferred embodiment of the invention. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 a perspective view of a conventional hospital bed on which a therapeutic mattress embodying this invention is mounted. 
     FIG. 2A is a schematic vertical sectional view of the inflatable tubular air bags assembled on the bed of FIG. 1, illustrating a normal or level position of the patient supporting inflatable air bags. 
     FIG. 2B is a view similar to FIG. 1 but illustrating in exagerated dimensions a first change in the relative inflation of longitudinally spaced groups of inflatable, patient supporting bags. 
     FIG. 2C a view similar to FIG. 1 but illustrating in exaggerated dimensions a second change in the relative inflation of longitudially spaced groups of inflatable, patient supporting bags. 
     FIG. 2D is a view similar to FIG. 1 but illustrating in exaggerated dimensions a third change in the relative inflation of longitudinally spaced groups of inflatable, patient supporting bags. 
     FIG. 2E is a view similar to FIG. 1 but illustrating in exaggerated dimensions a fourth change in the relative inflation of longitudinally spaced groups of inflatable patient support air bags. 
     FIG. 2F is a view similar to FIG. 1 but illustrating in exaggerated dimensions a fifth change in the relative inflation of longitudinally spaced groups of inflatable, patient supporting air bags. 
     FIG. 2G is a view similar to FIG. 1 but illustrating in exaggerated dimensions a sixth change in the relative inflation of longitudinally spaced groups of inflatable, patient supporting air bags. 
     FIG. 3 is a partial perspective view of a foam pad on which the inflatable patient supporting air bags are mounted. 
     FIG. 4 is a vertical sectional view taken through one of the inflatable patient supporting air bags and the underlying foam pad. 
     FIG. 5A is a perspective view of a patient supporting inflatable air bag. 
     FIG. 5B is a perspective view of a patient supporting inflatable bag constructed to provide a greater air loss than the bag of FIG. 5A. 
     FIG. 6 is a schematic diagram of the piping for supplying pressured air to the various groups of inflatable tubular elements. 
     FIG. 7 is an exploded perspective view of the air pump, pressure control valves and control circuitry contained in the control box for the therapeutic mattress. 
     FIG. 8 is an enlarged scale elevational view of the three control valves for controlling air pressure in the three primary air supply conduits for three groups of patient supporting air bags. 
     FIG. 9 is a partial sectional view taken on the plane 9--9 of FIG. 8. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring to FIG. 1, there is shown a conventional hospital bed 1 having a main frame 1a supported on a plurality of depending wheels 2. Headboard 3 and footboard 4 are secured in upstanding relation to main frame 1a. Side rail guards 5 are pivotally mounted to the sides of main frame 1a and are shown in their lowered position. A mattress supporting surface 6 is mounted on main frame 1a. 
     A fabric enclosed rectangular foam pad 7 is positioned in overlying relation to mattress supporting surface 6. An upstanding fabric wall 7a is secured to at least the two longitudinal sides of the foam pad 7 and preferably extends around the entire periphery of pad 7 to define a peripheral wall. 
     A plurality of inflatable tubular elements or bags 10 formed of low air loss material are provided, one of which is shown in FIG. 5a. The length of tubular elements 10 corresponds to the width of the pad 7 and the inflated diameters are in the range of 4 to 6 inches, so that 12, 15 or 18 of the inflated elements 10 may be disposed in side by side relationship within the peripheral wall 7 to cover the entire area of a normal adult bed and form a patient supporting surface. 
     Each end of the inflatable tubular elements 10 are detachably secured to the adjacent portion of the upstanding wall 7a. While snap fasteners could be employed, the preferred embodiment of this invention utilizes a pair of fabric hook and loop fastener strips 11a and 11b sold under the trademark VELCRO respectively secured to the top and bottom edges of the ends 10a of each inflatable tubular element 10, which cooperate with a VELCRO strip 12 secured to the wall 7a at each position of the inflatable elements 10. See FIGS. 4 and 5A. Near the bottom of the upstanding wall 7a, beneath the location of each VELCRO strip 12, a slot 7a is provided through the wall 7a. The top VELCRO strip 11a has VELCRO fabric hooks on both of its faces. Each top strip 11a is folded downwardly around wall 7a to engage VELCRO strip 12. The bottom VELCRO strip 11b is inserted through the adjacent slot 7a and secured to the VELCRO strip on the outer face of top strip 11a of each inflatable element 10. Thus the inflatable tubular elements 10 are individually secured in position within the upstanding wall 7 a. 
     Other alternative means for connecting the tubular elements 10 to pad 7 may also be preferred. For instance, tabls 11a and 11b may both be substituted with double-sided VELCRO loop material; and hook strips 12 may be modified to envelope tabs 11a and 11b once they are secured thereto. 
     If desired, for protection of the inflatable elements 10 from body fluids and to provide a smooth surface for overlaying a sheet thereon, a plastic or fabric cover 13 may be applied in the manner indicated in FIG. 1 and secured by snap fasteners 13a to the side of bed frame 1a. 
     As shown in FIG. 5A, each of the tubular inflatable elements 10 is inflated through a projecting filler tube 10b. In accordance with this invention, a plurality of longitudinally spaced inflatable elements 10 are interconnected to form a group receiving pressured air from a common supply conduit. The number of inflatable elements in each group may vary in accordance with the total number of inflatable elements. Preferably, 15 inflatable elements are utilized for the conventional adult hospital bed, so three sets of five elements in each group are formed. Thus as schematically shown in FIG. 6, starting at the footboard, the first, fourth, seventh, tenth and thirteenth elements would be interconnected by conduits 16 to a first primary conduit 20a. The second, fifth, eighth, eleventh and fourteenth inflatable elements would be connected by conduits 17 to a second primary conduit 20b. The remaining five inflatable elements would be connected by conduits 18 to a third primary conduit 20c. Similar groupings of sets of two, four or more may be substituted with corresponding changes in the air supply system, although primary aspects of the invention are best represented in the preferred embodiment. 
     The three primary conduits 20a, 20b and 20c extend from their respective connection points with secondary conduits 16, 17 and 18 to three sources of variable air pressure disposed in a box 22 which may be conveniently hung on the footboard 3. Within the box 22, as illustrated by FIG. 7, there is an electric motor driven air pump 24 which supplies pressured air to a header 26 having three flexible outlet pipes 26a, 26b and 26c. These flexible pipes respectively extend through motor controlled valves 31, 32, and 33. See FIGS. 8 and 9. The valves respectively have motors 31a, 32a, and 33a. Such motors are controlled to respectively provide differing degrees of axial movement of internally threaded blocks 31b, 32b and 33b, which compress the respective flexible outlet pipes 26a, 26b and 26c to vary the output pressures available at such pipes. Pipes 26a, 26b and 26c are respectively connected to the primary conduits 20a, 20b  and 20c. Thus the three groups of inflatable tubular elements may be expanded or contracted by varying the outlet pressures of flexible pipes 26a, 26b and 26c. 
     Conventional manually operable controls are provided in control box 22 to provide the desired sequence of raising and lowering the fluid pressures in the various groups of inflatable tubular elements. Only a slight periodic increase or decrease in pressure from a normal median pressure is required to reduce the possibility of bed sores. Many sequences of pressure variation are possible. FIGS. 2A-2G schematically indicate a desirable sequence. In these Figures, the numeral M indicates a median inflatable pressure, H indicates a slightly higher pressure than the median, and L indicates a slightly lower pressure than the median. Thus all of the patient supporting surfaces may be periodically moved vertically in a wave-like configuration along the length of the bed to vary the pressure on those portions of the patient&#39;s body supported by a particular group of inflated tubular elements. FIG. 2A is a schematic vertical sectional view of the inflatable tubular air bags assembled on the bed of FIG. 1, illustrating a normal or level position of the patient supporting inflatable air bags. FIG. 2B is a view similar to FIG. 1 but illustrating in exaggerated dimensions a first change in the relative inflation of longitudinally spaced groups of inflatable, patient supporting bags. FIG. 2C is a view similar to FIG. 1 but illustrating in exaggerated dimensions a second change in the relative inflation of longitudially spaced groups of inflatable, patient supporting bags. FIG. 2D is a view similar to FIG. 1 but illustrating in exaggerated dimensions a third change in the relative inflation of longitudinally spaced groups of inflatable, patient supporting bags. FIG. 2E is a view similar to FIG. 1 but illustrating in exaggerated dimensions a fourth change in the relative inflation of longitudinally spaced groups of inflatable patient support air bags. FIG. 2F is a view similar to FIG. 1 but illustrating in exaggerated dimensions a fifth change in the relative inflation of longitudinally spaced groups of inflatable, patient supporting air bags. FIG. 2G is a view similar to FIG. 1 but illustrating in exaggerated dimensions a sixth change in the relative inflation of longitudinally spaced groups of inflatable, patient supporting air bags. Note, though, that other inflation sequences will still fall within certain aspects of the present invention. For instance, the cycle can be adjusted to start with all cushions partially or fully deflated and still other changes can be made, without falling outside the scope of all aspects of the invention. 
     While all of the inflatable tubular elements may be formed of a low air loss material, in a preferred embodiment of the invention the three inflatable elements which provide support for the buttocks and lower back portions of the patient&#39;s body are each provided with a strip of high air loss or perforated material 11, as shown in FIG. 5B, thus providing an increased flow of air, particularly heated air, to those portions of the patient&#39;s body resting thereon. 
     Those skilled in the art will recognize that variations in construction of the inflatable tubular elements are readily possible, and some variations have been pointed out herein. It is intended that all such variations fall within the scope of the appended claims.