Abstract:
A pressure reducing cushion with selective pressure point relief features at least two air bladders, and a foam outer layer covering the air bladders. Each air bladder consists of an impervious to air sheet material which surrounds an open celled compressible foam material. Attached to the air bladder is an air flow tube and attached to the air flow tube is a flow control element. When the flow control element is open air from the atmosphere is able to communicate with the interior of the open celled compressible foam material through the air flow tube in combination with the flow control element. The open celled compressible foam material is of such a characteristic that once it is deformed it tends to regain its original shape, thus filling the air bladder with air, if the flow control element is open. Such a structure allows the cushion to be adjusted for maximum firmness, by not allowing air to leave the air bladders; minimum firmness is achieved by leaving the flow control element open, thus allowing air to be expelled from the air bladder; and selective pressure point relief is achieved by expelling air from an air bladder, closing its flow control element to prevent re-inflation, and allowing adjacent air bladders to be either filled with air and closing their flow control elements for maximum surrounding support, or left open for a more flotation-like support.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention concerns cushioning pads used in the field of health care to provide pressure reduction for the patient. The invention more particularly concerns cushion pads for patient care in wheelchairs, recliners, and other chairs used by patients in a health care environment. 
     2. Discussion of the Background 
     Previously existing cushioning pads have a number of shortcomings which can result in patient discomfort, and in a prolonged recovery period for the patient. Ideally, cushioning pads provide the lowest possible pressure on the supported surface of the patient and are able to substantially eliminate the pressure on the supported surface at selected locations on the patient. 
     One prior art device (Jacobson et al., U.S. Pat. No. 4,688,283) is constructed of a plurality of airtight air bladders each filled with foam material. Each air bladder is in contact with adjacent air bladders. The characteristic of the foam material is such that if it is compressed it will expand on its own, thus filling the bladder with air. Each air bladder has a valve connected to it, to individually regulate the amount of air that can flow into the air bladder. However, it produces an abrupt transition zone between an air bladder that is fully pressurized and an adjacent one that is completely evacuated, which creates patient discomfort. 
     Another prior art construction (Williams, U.S. Pat. No. 3,600,727) is similar to the prior art construction discussed above, but instead being filled with air, the air bladder is filled with a liquid. The bladders filled with a liquid tend to conduct body heat away from the patient which reduces blood flow and hence reduces the ability of the body to heal itself. Furthermore, this prior art construction contains all the disadvantages of the device described above, namely that the patient experiences discomfort due to the abrupt transition zone between pressurized and unpressurized fluid bladders. 
     Another prior art construction (Navach et al., U.S. Pat. No. 5,163,737) consists of a seat cushion and a backrest cushion. The seat cushion portion consists of a plurality of airtight, air bladders filled with a foam material. Adjacent air bladders are not in contact with each other. The air bladders are covered with a flexible polymer upholstery layer. Additionally this prior art construction contains an air valve for each air bladder to restrict the flow of air into and out of its respective air bladder. However, this prior art construction requires the use of an external pump or compressor to fill air bladders with air. 
     Thus, there is a need for a simple to use cushioning device that applies a substantially uniform pressure to the patient and which can selectively reduce the pressure at a point on the patient&#39;s body. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide a cushioning device that applies a substantially uniform pressure to the supported surface of a patient&#39;s body and which can also selectively reduce the pressure at a point on the patient&#39;s body. 
     In one form of the invention the pressure reducing cushion with selective pressure point relief takes the form of a cushion consisting of at least two air bladders which are covered with a foam outer layer. The air bladders are filled with an open celled compressible foam material. Each air bladder is connected to an air flow control element, which independently regulates the flow of air into and out of each air bladder. 
     In yet another form of the invention the pressure reducing cushion with selective pressure point relief takes the form of a cushion consisting of at least two air bladders attached to a cushion base layer, which are covered with a foam outer layer. The outer surface of the foam outer layer is surrounded by a cushion cover. The air bladders are filled with an open celled compressible foam material; and adjacent air bladders are in contact with each other. Each air bladder is connected to an air flow control element, which independently regulates the flow of air into and out of each air bladder. 
     In still another form of the invention the pressure reducing cushion with selective pressure point relief takes the form of a cushion consisting of at least two air bladders which are covered with a means for providing a reduction of any abrupt pressure transition between inflated and uninflated air bladders. The air bladders are filled with an open celled compressible foam material. Each air bladder is provided with a means for independently regulating the flow of air into and out of each air bladder. 
     Thus, Applicant&#39;s invention is superior to the prior art. Applicant&#39;s invention provides a cushioning device that produces a substantially uniform pressure on the supported surface of a patient and which can also selectively reduce the pressure at a point on the patient&#39;s surface, by using a foam outer layer in conjunction with the air bladders to achieve the desired objectives. The prior art fails to disclose the use of a foam outer layer covering air bladders, which provides the desired result. Furthermore, the prior art fails to disclose the use of a foam outer layer covering air bladders that are in contact with adjacent air bladders, which provides superior results. Such structural features distinguish Applicant&#39;s invention, structurally and functionally, over the prior art of Jacobson et al, Williams, and Navach et al. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
     FIG. 1 is a perspective view of a seat cushion with the foam outer layer removed and with the seat cushion cover removed, showing the seat cushion air bladders, the flow control elements, and the seat cushion base layer; 
     FIG. 2 is a partial cross-sectional view taken along the line  2 — 2  of FIG. 1, showing some of the elements interior of the cushion, and also showing the foam outer layer; 
     FIG. 3 is an exploded, perspective view of the seat cushion; 
     FIG. 4 is an exploded, perspective view of the backrest cushion; 
     FIG. 5 is an exploded, perspective view of the leg-rest cushion; 
     FIG. 6 is a top plan view of the combination of a leg-rest cushion, seat cushion, and a backrest cushion, all cushions having their respective outer layers removed and their respective covers removed; 
     FIG. 7 is a side view of the leg-rest cushion, seat cushion, and backrest cushion combination; 
     FIG. 8 is a side view of the leg-rest cushion, seat cushion, and backrest cushion combination, with respective covers and outer layers removed, shown in use to support a patient illustrated in phantom lines; and 
     FIG. 9 is a perspective view of the leg-rest cushion, seat cushion, and backrest cushion in combination, with respective covers and outer layers removed. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, and more particularly to FIG. 1 thereof, A seat cushion  20  has been created which provides for pressure reduction and selective pressure point relief on the surface of the patient. The embodiment of this invention is displayed in FIGS. 1,  2 , and  3 . FIG. 1 is a perspective view of the seat cushion  20  with the foam outer layer  180  removed and the seat cushion cover  186  removed, showing the placement of the parts. FIG. 1 illustrates the seat cushion base layer  22  to which are attached seat cushion air bladders: the rear seat cushion air bladder  98 , the rear left seat cushion air bladder  62 , the rear right seat cushion air bladder  80 , the front left seat cushion air bladder  128 , and the front right seat cushion air bladder  154 . As shown in FIGS. 1 and 3, the rear left seat cushion air bladder  62  is inserted into a cavity  114  provided for in the rear seat cushion air bladder  98 , and the rear right seat cushion air bladder  80  is inserted into a cavity  112  which is provided for in the rear seat cushion air bladder  98 , the front right seat cushion air bladder  154  is attached to the seat cushion base layer top side  24  near the corner defined by the seat cushion base layer front side  28  and the seat cushion base layer right side  30  and is in contact with the rear seat cushion air bladder  98  and the front left seat cushion air bladder  128 , the front left seat cushion air bladder  128  is attached to the seat cushion base layer top side  24  near the corner defined by the seat cushion base layer front side  28  and the seat cushion base layer left side  26  and is in contact with the rear seat cushion air bladder  98  and the front right seat cushion air bladder  154 . The air bladders are attached to the substantially rigid cushion base layer so as to maintain their relative positions. The air bladders are sized, shaped and arranged relative to one another so as to provide support for the uneven body surface contours of a single individual. 
     FIG. 1 further illustrates an air flow tube  76  connected to the rear left seat cushion air bladder  62  and a flow control element  78  connected to the air flow tube  76 , an air flow tube  94  connected to the rear right seat cushion air bladder  80  and a flow control element  96  connected to the air flow tube  94 , an air flow tube  124  connected to the rear seat cushion air bladder  98  and a flow control element  126  connected to the air flow tube  124 , an air flow tube  150  connected to the front left seat cushion air bladder  128  and a flow control element  152  connected to the air flow tube  150 , and an air flow tube  176  connected to the front right seat cushion air bladder  154  and a flow control element  178  connected to the air flow tube  176 . 
     FIG. 2 is a partial cross-sectional view taken along section line  2 — 2  of FIG.  1 . FIG. 2 displays the use of the foam outer layer  180  covering the top sides of the seat cushion air bladders  64 ,  82 ,  110 ,  140 ,  166 , and the rear seat cushion air bladder rear side  106 , the rear seat cushion air bladder left side  100 , the rear seat cushion air bladder right side  104 , the front left seat cushion air bladder left side  130 , the front left seat cushion air bladder front side  132 , the front right seat cushion air bladder front side  158 , and the front right seat cushion air bladder right side  160 . FIG. 2 further illustrates the use of the seat cushion cover  186  which envelops the foam outer layer outer surface  182 . Further, FIG. 2 shows the front left seat cushion air bladder  128  in an expanded state, the rear seat cushion air bladder  98  in an expanded state, and the rear left seat cushion air bladder  62  in a compressed state. 
     FIG. 3 is an exploded pictorial view of the seat cushion  20 . Illustrated in FIG. 3 is the seat cushion base layer  22  which contains a rear seat cushion air bladder channel  36 , a rear left seat cushion air bladder channel  38 , a rear right seat cushion air bladder channel  40 , a front left seat cushion air bladder channel  42 , and a front right seat cushion air bladder channel  44 . Attached to the seat cushion base layer  22  are a rear right seat cushion fabric strip  46  attached near the seat cushion base layer rear side  32  and near the seat cushion base layer right side  30  towards the seat cushion base layer bottom side  34  and attached to the rear right seat cushion fabric strip  46  is a rear right seat cushion fabric strip fastener means  48 , a rear left seat cushion fabric strip  50  attached near the seat cushion base layer rear side  32  and near the seat cushion base layer left side  26  towards the seat cushion base layer bottom side  34  and attached to the rear left seat cushion fabric strip  50  is a rear left seat cushion fabric strip fastener means  52 , a front right seat cushion fabric strip  54  connected near the seat cushion base layer front side  28  near the seat cushion base layer right side  30  towards the seat cushion base layer bottom side  34  and attached to the front right seat cushion fabric strip  54  is a front layer seat cushion fabric strip fastener mean  56 , and a front left seat cushion fabric strip  58  connected near the seat cushion base layer front side  28  and near the seat cushion base layer left side  26  towards the seat cushion base layer bottom side  34  and attached to the front left seat cushion fabric strip  58  is a front left seat cushion fabric strip fastener means  60 . 
     The rear seat cushion air bladder  98  is illustrated in FIG. 3 showing its left side  100 , front side  102 , right side  104 , rear side  106 , bottom side  108 , top side  110 , and having a rear right seat cushion air bladder cavity  112  and a rear left seat cushion air bladder cavity  114 . The interior region  118  is filled with an open celled compressible foam material  122 . Connected to the rear seat cushion air bladder  98  is an airflow tube  124 , and a flow control element  126  is connected to the airflow tube  124 . The rear seat cushion air bladder bottom side  108  is attached to the seat cushion base layer top side  24  such that the rear seat cushion air bladder air flow tube  124  is situated in the seat cushion base layer rear seat cushion air bladder channel  36 . 
     The rear left seat cushion air bladder  62  has a top side  64 , a bottom side  66 , an exterior surface  68 , and an interior region  70  which is filled with an open celled compressible foam material  74 . The rear left seat cushion air bladder  62  is situated in the rear left seat cushion air bladder cavity  114  and the rear left seat cushion air bladder air flow tube  76  is situated in the rear left seat cushion air bladder channel  38 , the rear left seat cushion air bladder exterior surface  68  is in contact with the exterior surface  116  of the rear seat cushion air bladder  98 , and the rear left seat cushion air bladder bottom side  66  is in contact with the seat cushion base layer top side  24 . 
     The rear right seat cushion air bladder  80  has a top side  82 , a bottom side  84 , an exterior surface  86 , and an interior region  88  which is filled with an open celled compressible foam material  92 . The rear right seat cushion air bladder  80  is situated in the rear right seat cushion air bladder cavity  112  and the rear right seat cushion air bladder air flow tube  94  is situated in the rear right seat cushion air bladder channel  40 ; the rear right seat cushion air bladder exterior surface  86  is in contact with the exterior surface  116  of the rear seat cushion air bladder  98 , and the rear right seat cushion air bladder bottom side  84  is in contact with the seat cushion base layer top side  24 . 
     The front left seat cushion air bladder  128  has a left side  130 , a front side  132 , a right side  134 , a rear side  136 , a bottom side  138 , and a top side  140 , and an interior region  144  which is filled with an open celled compressible foam material  148 . Connected to the front left seat cushion air bladder  128  is an air flow tube  150 , and a flow control element  152  is connected to the air flow tube  150 . The front left seat cushion air bladder bottom side  138  is attached to the seat cushion base layer top side  24 , the front left seat cushion air bladder rear side  136  is in contact with the rear seat cushion air bladder front side  102 , and the front left seat cushion air bladder right side  134  is in contact with the front right seat cushion air bladder left side  156 , and the front left seat cushion air bladder air flow tube  150  is situated in the front left seat cushion air bladder channel  42 . 
     The front right seat cushion air bladder  154  has a left side  156 , a front side  158 , a right side  160 , a rear side  162 , a bottom side  164 , a top side  166 , and an interior region  170  which is filled with an open celled compressible foam material  174 . Connected to the front right seat cushion air bladder  154  is an airflow tube  176 , and a flow control element  178  is connected to the airflow tube  176 . The front right seat cushion air bladder bottom side  164  is in contact with the seat cushion base layer top side  24 , the front right seat cushion air bladder left side  156  is in contact with the front left seat cushion air bladder right side  134 , the front right seat cushion air bladder rear side  162  is in contact with the rear seat cushion air bladder front side  102 , and the front right seat cushion air bladder air flow tube  176  is situated in the front right seat cushion air bladder channel  44 . 
     A foam outer layer  180 , has an outer surface  182  and an inner surface  184 , covers the exposed surfaces of the seat cushion air bladders and the seat cushion base layer which includes: the seat cushion base layer left side  26 , the seat cushion base layer front side  28 , the seat cushion base layer right side  30 , the seat cushion base layer rear side  32 , the rear left seat cushion air bladder top side  64 , the rear right seat cushion air bladder top side  82 , the rear seat cushion air bladder top side  110 , the rear seat cushion air bladder left side  100 , the rear seat cushion air bladder right side  104 , the rear seat cushion air bladder rear side  106 , the front left seat cushion air bladder left side  130 , the front left seat cushion air bladder top side  140 , the front left seat cushion air bladder front side  132 , the front right seat cushion air bladder front side  158 , the front right seat cushion air bladder front side  160 , the front right seat cushion air bladder top side  166 . A seat cushion cover  186  envelopes the seat cushion foam outer layer outer surface  182 . 
     The seat cushion base layer  22  is preferably made of a rigid, waterproof, closed cell, polyurethane foam material. The foam outer layer  180  is preferably made of a soft, highly resilient foam material such as polyurethane or a vaso-elastic material, having a thickness between 1 inch and 1.5 inches, a density of 2.4 pounds per cubic foot, and an Indentation Force Deflection in the range of 15 to 18 pounds. The seat cushion cover  186  is preferably made of a flexible fabric such as nylon, nylon spandex, cotton-Lycra, or cotton-spandex, which is water proof, water repellant, or breathable cloth and may be laminated with a polyurethane foam material. The open celled compressible foam material  74 ,  92 ,  122 ,  148 , and  174 , of the seat cushion air bladders  62 ,  80 ,  98 ,  128 , and  154 , is preferably made of an open celled polyurethane foam material and is dye-cut into the preferred shapes, having a thickness of 1.5 inches, a density of 1.8 pounds per cubic foot, and an Indentation Force Deflection in the range of 35 to 45 pounds. The seat cushion air bladder exterior surfaces  68 ,  86 ,  116 ,  142 , and  168 , are preferably made of an impervious to air vinyl or urethane sheeting material. These seat cushion air bladders  62 ,  80 ,  98 ,  128 , and  154 , are constructed by, but not limited to, heat sealing the vinyl or urethane sheeting material that comprises the exterior surfaces  68 ,  86 ,  116 ,  142 , and  168 , of the seat cushion air bladders  62 ,  80 ,  98 ,  128 , and  154 , around the dye-cut open celled polyurethane foam material sections  74 ,  92 ,  122 ,  148 , and  174 , creating a unified body of independent seat cushion air bladders. The seat cushion air bladders  62 ,  80 ,  98 ,  128 , and  154 , are secured to the seat cushion base layer  22  through use of an adhesive glue. The seat cushion fabric strip fastener means  48 ,  52 ,  56 , and  60 , are preferably constructed of snaps, full width zippers, or hook fastening elements which become embedded in loop fastening elements. The fastenings of this type, hook and loop, are marketed under the trademark “VELCRO.” The air flow control elements  78 ,  96 ,  126 ,  152 , and  178 , are preferably constructed of an open and close valve. 
     The seat cushion air bladders  62 ,  80 ,  98 ,  128 , and  154 , are connected to their respective air flow tubes  76 ,  94 ,  124 ,  150 , and  176 , in such a way that when the air bladder is compressed, air is expelled from the seat cushion air bladder through the respective air flow tube and through the respective flow control element. When pressure is removed or reduced from the seat cushion air bladders  62 ,  80 ,  98 ,  128 , and  154 , the respective open celled compressible foam materials  74 ,  92 ,  122 ,  148 , and  174 , in an effort to return to its normal shape, provides the force to draw air in through the respective air flow tube  76 ,  94 ,  124 ,  150 , and  176 , and through the respective flow control elements  78 ,  96 ,  126 ,  152 , and  178 , to refill the seat cushion air bladders  62 ,  80 ,  98 ,  128 , and  154 , with air. 
     The seat cushion  20  provides pressure reduction since the seat cushion air bladders  62 ,  80 ,  98 ,  128 , and  154 , are in contact with each other, thus maximizing the surface area of the seat cushion  20  which is supported by air bladders. If gaps were present between the air bladders attached to the seat cushion base layer  22  then a smaller surface area would support the patient, thus resulting in a larger contact pressure on the patient&#39;s supported surface. The seat cushion  20  may be placed on any surface such as a wheelchair, a recliner, or any other chair. The soft, resilient seat cushion foam outer layer  180  also provides the patient with a surface that helps to distribute the pressure. Each seat cushion air bladder  62 ,  80 ,  98 ,  128 , and  154 , are individually controlled due to their respective flow control elements  78 ,  96 ,  126 ,  152 , and  178 , to be adjusted for the patient&#39;s comfort, and wound treatment. The seat cushion air bladders  62 ,  80 ,  98 ,  128 , and  154 , are adjusted by compressing the selected seat cushion air bladder while its respective flow control element is in an open state so that air may flow out of the selected seat cushion air bladder through the respective seat cushion air bladder air flow tube and out the respective seat cushion air bladder flow control element into the atmosphere, at the desired depth of compression the respective seat cushion air bladder flow control element is closed; thus preventing the selected seat cushion air bladder from expelling air or being filled with air. 
     In another mode of operation a selected seat cushion air bladder or all seat cushion air bladders may have their respective flow control elements  78 ,  96 ,  126 ,  152 , and  178 , left in the open position, thus providing “floatation”. Floatation provides for large deflections of the surface of the seat cushion  20 . When the patient sits on the seat cushion  20  the seat cushion air bladders underneath the patient become compressed, thus expelling air from the effected seat cushion air bladders to the atmosphere. When the patient moves, leans, gets up, or repositions themselves the effected seat cushion air bladders will either expand, if pressure has been removed from them, or become compressed, if pressure has been applied to them. In the flotation mode, the support pressure reacted on the patient&#39;s surface is provided by the spring rate of the open celled compressible foam material of the seat cushion air bladders  74 ,  92 ,  122 ,  148 , and  174 . This mode of operation provides for a large cushioning effect. 
     As an example of the selective pressure point relief that can be provided by using the seat cushion  20  it will be shown how such relief will be provided to the left ischial tuberosity of the patient. Covering the seat cushion air bladders  62 ,  80 ,  98 ,  128 , and  154 , are the seat cushion top layer  180  and the seat cushion cover  186 . The combined use of the seat cushion foam outer layer  180  and the seat cushion cover  186  provides a soft and comfortable surface for the patient to sit on. In this example, the rear left seat cushion air bladder flow control element  78  is opened, then the rear left seat cushion air bladder  62  is manually compressed expelling the contained air, the rear left seat cushion air bladder flow control element  78  is then closed off, then the flow control element of the adjacent seat cushion air bladder, the rear seat cushion air bladder  98  flow control element  126  is opened, the opened cell compressible foam material  122  of the rear seat cushion air bladder  98  is allowed to expand, thus filling the rear seat cushion air bladder  98  with air, and then the rear seat cushion air bladder flow control element  126  is closed. The seat cushion foam outer layer  180  which encases the seat cushion air bladders  62 ,  80 ,  98 ,  128 , and  154 , creates a gradual support pressure transition region. The gradual support pressure transition region spans from a location on top of the fully expanded rear seat cushion air bladder  98  and extends across the edge of that seat cushion air bladder to the region above the fully compressed rear left seat cushion air bladder  62  then across to the rear seat cushion air bladder  98  which is fully inflated. The portion of the seat cushion top layer  180  situated above the fully inflated rear seat cushion air bladder  98  provides full weight carrying ability, thus the pressure on the patient&#39;s surface is high. The portion of the seat cushion foam outer layer  180  spanning the edge between the fully inflated rear seat cushion air bladder  98  and the compressed rear left seat cushion bladder  62  provides a smooth transition into a region where the support pressure on the patient&#39;s surface reaches a minimum. Such a combination of inflated and deflated seat cushion air bladders results in selective pressure point relief underneath the patient&#39;s left ischial tuberosity. Such selective pressure point relief enhances wound healing and can help prevent the creation of sores. This is just one example of the selective pressure point relief that can be provided with the seat cushion  20 , any combination of inflated and deflated seat cushion air bladders can be used to provide patient comfort and wound healing, while the bony prominence and surrounding tissue rest in a desirable position without excessive pressure. 
     All of the above-mentioned modes of operation are provided without the use of an external pump to either fill or evacuate the seat cushion air bladders  62 ,  80 ,  98 ,  128 , and  154 , with air. 
     In another embodiment of the invention a backrest cushion  188  has been created which provides for pressure reduction and selective pressure point relief on the surface of the patient&#39;s back. The embodiment of this invention is displayed in FIG.  4 . FIG. 4 is an exploded pictorial view of the backrest cushion  188 . Illustrated in FIG. 4 is the backrest cushion base layer  190 , the right side backrest cushion air bladder  246 , the left side backrest cushion air bladder  220 , the upper center backrest cushion air bladder  272 , the lower center backrest cushion air bladder  298 , the foam outer layer  324 , and the backrest cushion cover  330 . Attached to the backrest cushion base layer  190  are a bottom right backrest cushion fabric strip  212 , and a bottom left backrest cushion fabric strip  216 . Attached to each backrest cushion fabric strip  212 ,  216 , is a fabric strip fastener means  214 ,  218 . 
     Each backrest cushion air bladder  246 ,  272 ,  298 , and  220 , is filled with an open celled compressible foam material  266 ,  318 ,  292 , and  240 , is connected to an airflow tube  268 ,  294 ,  320 , and  242 , and a flow control element  270 ,  296 ,  322 , and  244 , is attached to each airflow tube  268 ,  294 ,  320 , and  242 . 
     The construction and operation of the backrest cushion  188  is similar to that of the seat cushion  20 . As such, it is believed that the structure and operation of the backrest cushion  188  have been fully disclosed. 
     In another embodiment of the invention, a leg-rest cushion  332  has been created which provides for pressure reduction and selective pressure point relief on the surface of the patient&#39;s legs. The embodiment of this invention is displayed in FIG.  5 . FIG. 5 is an exploded pictorial view of the leg-rest cushion  332 . Illustrated in FIG. 5 is the leg-rest cushion base layer  334 , six identical substantially horizontal air bladders  358 , the leg-rest cushion foam outer layer  384 , and the leg-rest cushion cover  390 . 
     Attached to the leg-rest cushion base layer  334  are a top right leg-rest cushion fabric strip  350 , and a top left leg-rest cushion fabric strip  354 . Attached to each leg-rest cushion fabric strip  350 ,  354 , is a leg-rest cushion fabric strip fastener means  352 ,  356 . 
     Each of the six leg-rest cushion air bladders is identical. Each leg-rest cushion air bladder  358  is filled with an open celled compressible foam material  378 , is connected to an airflow tube  380 , and a flow control element  382  is connected to the airflow tube  380 . 
     The construction and operation of the leg-rest cushion  332  is similar to that of the seat cushion  20 . As such, it is believed that the structure and operation of the leg-rest cushion  332  have been fully disclosed. 
     FIG. 6 is a top plan view of the combination of a leg-rest cushion  332 , a seat cushion  20 , and a backrest cushion  188 , all cushions having their respective foam outer layers removed and their respective covers removed. FIG. 6 further illustrates the locations of the air bladders  220 ,  246 ,  272 ,  298 ,  98 ,  62 ,  80 ,  128 ,  159 , and  358 . 
     FIG. 7 is a side view of FIG. 6, showing the leg-rest cushion  332 , the seat cushion  20 , and the backrest cushion  188  combination. Again, as in FIG. 6 the foam outer layers of the cushions are removed as are the respective covers. FIG. 6 additionally shows the right side cushion fabric strips  212 ,  46 ,  54 , and  350  and their associated fastener means  214 ,  48 ,  56 , and  352 . 
     FIG. 8, is a side view as in FIG. 7 showing the combination of a leg-rest cushion  332 , a seat cushion  20 , and a backrest cushion  188 , with their respective covers and foam outer layers removed. FIG. 8 additionally shows a patient illustrated in phantom lines. 
     FIG. 9 is a perspective view of the leg-rest cushion  332 , the seat cushion  20 , and the backrest cushion  188  in combination, with their respective covers and foam outer layers removed. 
     Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.