Abstract:
A foam cushion suitable for use such as with a wheelchair provides a combination of general pressure relief and positioning control over legs of a patient possibly otherwise having reduced or impaired motor control skills. A desired leg position is achieved by separating the legs and supporting them in a generally parallel position. Two base pieces have predetermined upper profiles and are glued to an upper support element having integrated cubic elements for pressure relief. Channels between adjacent cubic elements facilitate flexure of the upper element to conform to the contours of the two base pieces. Relatively high ILD foam characteristics and relatively high foam densities combined with the subject structure give good results for support and for product life, including compression fatigue considerations.

Description:
PRIORITY CLAIM 
     This application is based on Provisional Application having U.S. Ser. No. 60/036,037 filed Jan. 22, 1997, and priority is hereby claimed therefrom. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to improved support apparatus and methodology in general, and in particular to improved multi-section foam positioning technology. 
     A significant problem for immobile patients, such as wheelchair patients or others confined by limited walking ability, is the occurrence of pressure sores and related tissue damage. Hence, there is a general need for pressure relief in such immobile patients. 
     A particular problem for typical patients in a prolonged seating environment is that the patients may suffer from a loss of motor skills or other abilities to manipulate their legs. This, and other general aspects of their condition, can also lead to positioning problems. For example, the legs of a patient may be excessively abducted (drawn apart or separated) or excessively adducted (drawn together or closed). The more ideal position is for the legs to be separated and generally parallel to one another as they project forwardly from the lower torso of the patient. 
     As generally well known, the projecting ischial aspect at the base of the spine provides another comfort concern point for long term seated patients. 
     Another aspect of pressure relief deals not just with the vertical components of pressure, but the lateral or horizontal components, often referred to as shear pressures. Oftentimes, a support arrangement designed to address vertical pressures will address shear or lateral pressure forces less well, or vice versa. Still further, introducing lateral forces for the purpose of controlling leg position, or positioning of other bodily features, raises the possibility of interjecting undesired shear forces. 
     Yet another aspect of modern health care demands is an issue of providing combinations of advantageous features with an embodiment and technology which is also cost effective. 
     To an extent, improved pressure dispersion can be achieved with a multi-section approach having respective areas specialized for support of different physical characteristics. See, for example, commonly owned U.S. Pat. No. 4,862,538, entitled “MULTI-SECTION MATTRESS OVERLAY FOR SYSTEMATIZED PRESSURE DISPERSION,” the complete disclosure of which is fully incorporated herein by reference. One challenge of the technical aspects of wheelchair cushions and similar environments is finding practical ways to achieve advantageous results in smaller spaces as have been achieved with larger scale technologies designed for full mattress overlays, such as in the above-referenced &#39;538patent. 
     SUMMARY OF THE INVENTION 
     The present invention recognizes and addresses various of the foregoing problems, and others, concerning support of long term confined patients, or others for whom improved seating comfort is desired. Thus, broadly speaking, a principal object of this invention is improved cushion technology. More particularly, a main concern is improved apparatus and methodology for multi-section foam positioning cushions. 
     It is therefore another particular object of the present invention to provide a foam apparatus adapted for simultaneously providing general pressure relief and positioning control for the user. 
     It is another general object of the present invention to provide an apparatus achieved with methodology which is cost effective, while still achieving advances in practical performance. 
     Still a further more particular object is to provide an improved foam-based apparatus for comfortably seating long term care patients with their legs guided to an ideal position (i.e., generally separated and parallel to one another). 
     Additional objects and advantages of the invention are set forth in, or will be apparent to those of ordinary skill in the art from, the detailed description herein. Also, it should be further appreciated that modifications and variations to the specifically illustrated and discussed features, steps, materials, or devices hereof may be practiced in various embodiments and uses 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 means, features, materials, or steps for those shown or discussed, and the functional or positional reversal of various parts, features, steps, or the like. 
     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, steps, or elements, or their equivalents (including combinations of features or steps or configurations thereof not expressly shown in the figures or stated in the detailed description). One exemplary such embodiment of the present invention relates to an improved apparatus comprised of plural elements, including two respective forward and rear base pieces, having predetermined contoured upper surfaces in support of an upper support element having respective elements for general pressure relief, in contact of a patient seated thereon. 
     Other aspects of the present exemplary embodiments concern use of plural sections joined to form a base, having respective upper contoured surfaces which are used to transmit the respective contours thereof onto larger, respective support elements integrally formed in an upper support element otherwise adhered to the base elements. With such apparatus and methodology, respective base elements may be efficiently manufactured and joined together to form a composite base having respective sections with different support contours. 
     Such apparatus and methodology is particularly advantageous for producing a support contour which varies in front to back profile as well as lateral or side to side profile. At the same time, such varying profiles may be advantageously achieved with cutting technology which operates in a single plane (i.e., either front to back or side to side). It is by combining such respective base multiple sections and upper support element that such additional advantage is achieved. 
     It is to be understood that the present invention applies equally to present methodology in association with manufacturing such improved apparatus as otherwise described herein. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     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: 
     FIG. 1 is a generally top and rear perspective view of exemplary embodiments of two base pieces, forward and rear, respectively, in exploded view before being joined in accordance with the invention; 
     FIG. 2 is a generally top and rear perspective view as in FIG. 1, but with the base pieces joined, and illustrating thereabove in exploded view an exemplary upper support element to be further joined to such two base pieces in accordance with this invention; 
     FIG. 3 is a generally top and rear perspective view similar to that as in present FIGS. 1 and 2, but with the respective exemplary base pieces and upper support element joined in accordance with the invention; 
     FIG. 4 is a generally top and front perspective, partial view of a typical conventional wheelchair sling-type seat arrangement, such as with which the present invention may be practiced; 
     FIG. 5 is a generally front elevational view of an exemplary embodiment of the subject invention as would be seen per the view line  5 — 5  indicated in present FIG. 4, when used with the typical wheelchair configuration generally and partially represented; 
     FIG. 6 is a rear elevational view of an exemplary embodiment of the present invention, focused on the foreground aspects of such view as would be seen per the view line  6 — 6  indicated in present FIG. 3, and also representing (partially) use thereof with a typical conventional wheelchair; 
     FIG. 7 is a generally front elevational view of the forward base element as otherwise represented in the present exemplary embodiment of the subject invention; and 
     FIG. 8 is a rear elevational view of the rearward base element otherwise represented in the present exemplary embodiment of the present invention. 
     Repeat use of reference characters throughout the present specification and appended drawings is intended to represent same or analogous features, elements, or steps of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     It is to be understood by those of ordinary skill in the art that the features and aspects of the subject invention, both as to apparatus and methodology as disclosed herein, may be practiced in various embodiments. Hence, the present description of an exemplary preferred embodiment is by way of example only, and not intended to limit the spirit or scope of the subject invention. 
     FIG. 1 illustrates a generally top and rear perspective view of two base pieces in accordance with an exemplary embodiment of the subject invention. A relatively forward base piece  10  is designed and situated so as to be joined to a generally rearward base piece  12  along respective angled joining surfaces  14  and  16 . While various angles may be practiced, an angle in a range of from about 40 degrees to about 60degrees provides an effective gradual sloping to an area generally  18 , forming a trailing edge surface of a central or projecting pommel generally  20  associated with the upper surface of base piece  10 . 
     In general, forward edge  22  of base piece  10  is turned towards the forward edge of a supporting wheelchair or similar. As will be understood by those of ordinary skill in the art, sides  24  and  26  comprise left and right, respectively, lateral edges of piece  10 , such that regions  28  and  30  of the upper surface of piece  10  respectively support left and right legs of a patient or user of the present embodiment. 
     Generally rearward base piece  12  has a central reduced area  32  relative to its lateral upper support surfaces  34  and  36 . Such reduced region  32  forms an ischial cavity which, together with a general front to rear reduction in the overall height of the apparatus, helps transfer support pressures from the buttocks and ischial area to the lower surfaces of the legs received above support areas  28  and  30 . 
     Those of ordinary skill in the art will appreciate that various commercial glues generally  38  may be applied between adjacent contact surfaces  14  and  16  so as to join the foamed material together. 
     Collectively, the respective surface profiles of the forward base piece  10  and rearward base piece  12  define an overall predetermined contoured approach to support of a patient thereon. However, it is preferred that a further support element be interposed between a patient and such upper surfaces of base elements  10  and  12 . 
     More particularly, FIG. 2 represents bonding of an upper support element generally  40  to the respective upper surfaces of base elements  10  and  12  as referenced above. As represented in the generally top and rear perspective view of present FIG. 2, various commercially available glues  38  or similar may be simply used between mutual contact surfaces for adhering element  40  to the respective base elements  10  and  12 . As shown, element  40  has relatively flat lower and upper surfaces  39  and  41 , respectively, prior to being secured to base elements  10  and  12 . 
     While various thicknesses may be practiced, the nominal thickness or “height” of upper support surface  40  is preferably about two inches, while the nominal thickness of the respective base elements  10  and  12  is preferably about one inch. 
     FIG. 3 represents an exemplary completed combination of upper support element  40  with base elements  10  and  12 . As may be seen in such generally top and rear perspective view, the previously relatively flat support element  40  has now assumed the contours of the respective base pieces  10  and  12 . With such approach, a readily manufactured element such as support element  40  is transformed into a much more complex support morphology, as well illustrated in present FIG.  3 . 
     FIG. 3 also represents a preferred embodiment of support element  40 , comprising an integral arrangement of adjacent protrusions  42 . As shown, preferably a plurality of such protrusions may be provided in generally cubic form, with cuts  44  defined therebetween, and further preferably with channels or ringed openings generally  46  formed in the bottom of the respective cuts  44 . As illustrated, operation of such cuts  44  and channels  46  very effectively enable the upper surface  41  of upper support element  40  to be contoured in accordance with the lower support pieces  10  and  12 , while the respective independent support elements  42  are substantially maintained in a generally vertical position, relative to the horizontal plane of the overall apparatus  48  in accordance with the subject invention. It is to be understood that different numbers and/or sizes of such elements  42 , and different depths of cuts and radius of curvature for channels  46  may be practiced, generally in keeping with the subject invention. 
     FIG. 4 shows a generally top and front perspective view of a typical conventional wheelchair configuration generally  50 , having respective lateral support bars  52  and  54 , and with a sling-type seat generally  56  supported therebetween. Such arrangement is most typical in relation to folding wheelchairs. The back support generally  58  may be similarly provided for folding, as illustrated, and as well known to those of ordinary skill in the art. 
     FIG. 5 shows a generally front elevational view of an exemplary embodiment generally  48  of the subject invention used in combination with a typical underslung wheelchair support  56 , generally as seen along the view line  5 — 5  of present FIG.  4 . As shown in such FIG. 5, the central ridge or pommel  20  is prominent, as are the respective support areas  28  and  30  for receiving the user&#39;s legs. With such arrangement, the pommel element  20  abducts the user&#39;s legs, while the respective lateral edges  26  and  24  of the base elements combine with the upper support element  40  to provide desired adduction of the user&#39;s legs to prevent them being excessively splayed open. 
     FIG. 6 illustrates a generally rear elevational view of the apparatus as illustrated in present FIG. 5, but with only the foreground portions of the upper support element  40  illustrated for the sake of clarity. As illustrated, the prominent rearward feature is the resulting depressed area  32  and relative higher regions  34  and  36 , which result from the profile of the generally rearward base piece  12 , as referenced above. Together they help form an ischial receiving area and help position the patient or user accordingly. 
     Both FIGS. 5 and 6 show an additional aspect of an exemplary feature preferred for wheelchair embodiments of the subject invention for use with typical wheelchair arrangements such as illustrated in present FIG.  4 . Such features are shown by the angled lower cut edges  64 / 66  and  60 / 62  adjacent lateral portions of respective base pieces  10  and  12 . Such lateral or angle cut surfaces  60 / 62  and  64 / 66  facilitate adaptation of the device generally  48  when under pressure between a user and the generally curved lower-slung support surface  56  of wheelchair  50 . Outline  57  shows the position which the bottom of apparatus  48  and the sling seat  56  would tend to take on if there were no pressure from a user. Seat  56  is shown in dotted line in both FIGS. 5 and 6, representing the position assumed generally by both the seat  56  and the bottom of apparatus  48  when in use, i.e., when under loading pressure. 
     FIG. 7 illustrates a front elevational view of an exemplary generally forward base element  10 . The central pommel generally  20  resides between regions  28  and  30 . Angled edges  64  and  66  are also provided generally for alignment with and function similar to cut edges  60  and  62  of base piece  12 , as referenced above. 
     A rear elevational view of the rearward base element  12  is represented in present FIG.  8 . Such FIG. 8 also shows the relative different thickness regions  32 ,  34 , and  36  of such base piece  12 . 
     As will be further understood by those of ordinary skill in the art from the collective disclosure herewith, there are different surface profiles achieved on a front to back basis with practice of the subject invention, as well as different lateral surface profiles. The invention, in a cost effective manner, provides simultaneous variations in both front to back and lateral modes, with such surface translations being transmitted to an otherwise generally flat upper support element. 
     Another advantage of practice of the present invention, both apparatus and methodology, is that the center pommel abducts the legs, but without any abduction pressures being carried to the rear quarters of the patient, due to the split profile feature. 
     It will be further understood by those of ordinary skill in the art that the two piece base simultaneously provides a filler for support structure while also serving as a base for contoured support of the upper support element. Such combination may be formed through use of variously commercially available glues, such as for use with open cell polyurethane materials. 
     As referenced above, the collective target nominal thickness of an exemplary preferred embodiment would be about three inches. While different cubes or other shapes may be practiced, an approximate two inch square nominal element (including gaps therebetween) could be used on the upper surface of element  40 . 
     Generally longer life of the product is obtained from preferably higher rated materials used. For example, to provide an overall device having dimensions of about 16 inches by 18 inches, and with a nominal three inch thickness, certain foam densities and ILD characteristics are preferred. ILD characteristic is the indentation load deflection of the foam body, and is defined as the number of pounds of pressure needed to push a 50 square inch circular plate into such main body an amount adequate to deflect such body a given percentage distance of its non-loaded thickness. For example, a 25% ILD rating would be the number of pounds of pressure needed to push a 50 square inch circular plate into the foam body to a point only 75% of its original thickness. 
     In the present exemplary embodiment, upper foam support element  40  may preferably have a density of about 2.8 pounds per cubic foot and a 25% ILD rating of about 55 pounds or higher. Such relatively higher readings provide good support and product life, especially against compression fatigue. It is to be understood that some variations in such numbers, resulting in an acceptable range, may be practiced in accordance with the invention, so long as relatively higher ranges are maintained. For example, a product with a 25% ILD characteristic lowered to about 35 pounds may under certain circumstances suffer “bottoming out,” which is a condition which fails to provide the desired patient support. 
     Similarly, the two base pieces may be provided with preferred characteristics which are in relatively higher ranges. Preferably, the two base pieces are of the same foam material, though differences could be practiced. When of the same material, a foam density of about 2.4 pounds per cubic foot and a 25 percent ILD characteristic of about 125 pounds or higher is preferred in some embodiments. The 25% ILD characteristic may also be stated in a range, with the low end of such range being generally down to about 90 to 100 pounds. Preferably, the density is maintained at at least 2.0 pounds per cubic foot, with higher densities also falling within the spirit and scope of the subject invention, so long as performance is maintained. 
     In addition to variations in the foam characteristics, dimensional variations may be practiced. Preferably, the base elements  10  and  12  have a nominal height of about 1 inch, tapering to 0.25 inches in the rear (central region  32  of base element  12 ). The pommel  20  or raised central point of forward base piece  10  may be about 1.5 inches thick, while the adjacent “valley” depth for areas  28  and  30  may be about 0.5 inches. In general, the front thickness of the base pieces is greater than at the rear, to help form the ischial pocket in region  32 . As understood by those of ordinary skill in the art, the contour of upper support element  40  then generally conforms with the contours of the respective base pieces  10  and  12 . 
     It is to be further understood that such upper support element  40  may be comprised of different embodiments than presently illustrated, combined with the same or different base pieces  10  and  12 . With such variations, different combinations of various respective embodiments of pieces  10 ,  12 , and  40  may themselves comprise different embodiments of the subject inventive apparatus  48  for use with a wheelchair  50  or in other desired support arrangement. 
     Also, different numbers of multiple sections (upper support elements or base pieces) may be joined together in some embodiments. As will be understood, the use for example of three base pieces obtains additional opportunities for varying the resulting complexity of the support profile of upper element(s)  40 . 
     It is to be further understood that variations and modifications not shown, such as wheelchair cushion covers or the like, may be practiced as desired or practical, so long as not to interfere with the advantageous functions of the subject invention herein otherwise described. 
     The foregoing presently preferred embodiments of both apparatus and methodology are exemplary only, and the attendant description thereof likewise is by way of words of example rather than words of limitation, and their use, does not preclude inclusion of such modifications, variations, and/or additions to the present invention as would be readily apparent to one of ordinary skill in the art, the full scope of the present invention being otherwise set forth throughout the present specification.