Patent Publication Number: US-6668405-B1

Title: Variable pressure relief inflated cushion

Description:
This application claims the benefit of U.S. provisional patent application Serial No. 60/260,561 filed Jan. 9, 2001 
    
    
     BACKGROUND 
     Persons with limited mobility, such as the elderly or persons confined to a wheelchair are susceptible to the development of pressure sores. Pressure sores are formed when the tissue is compressed for extended periods of time causing a restriction in the flow of blood. The exchange of nutrients and waste in the compressed tissue cells is slowed, resulting in skin breakdown and the formation of pressure sores. The retention of heat and moisture are two additional factors that contribute to the formation of pressure sores. Areas most vulnerable to pressure sore formation are bony areas having little tissue between the bone and the skin, including such areas as the ischial tuberosities, coccyx and sacrum. 
     U.S. Pat. No. 6,216,299 discloses a wheelchair cushion system wherein the cushion includes an array of inflatable square pockets including first and second interconnected groupings of pockets interspersed throughout the array which are independently inflated and deflated on a predetermined schedule in order to vary the location of contact between the cushion and the body of a person seated on the cushion. 
     While providing a significant advance in efforts to reduce the development of pressure sores on persons confined to wheel chairs, pressure sores remain a persistent problem for those with limited mobility and a continuing need exists for further improvements in devices capable of reducing or eliminating the development of pressure sores caused by daily prolonged seating. 
     SUMMARY OF THE INVENTION 
     The invention is a cushion having a plurality of inflatable and deflatable cells useful for periodically shifting the points of contact between the cushion and a body supported by the cushion in order to reduce or eliminate the development of pressure sores. 
     A first embodiment of the cushion has at least two encircling cells shaped so as to define a central concavity in the upper surface of each of the encircling cells. 
     A second embodiment of the cushion has at least one cell repositionably attached to the first major surface of a base for allowing repositioning of the cell on the base. It is generally preferred that at least one of the encircling cells is repositionably attached to the first major surface of the base. Such repositionability of the cells allows positioning of the cells to correspond with the location of one of more of the ischial tuberosities, coccyx, and sacrum of each specific user and thereby provide appropriate pressure relief. 
     A third embodiment of the cushion has at least two contoured cells with each contoured cell independently defining a longitudinally extending laterally concave channel on the upper surface of the contoured cell. 
     A fourth embodiment of the cushion has a majority of the cells symmetrically configured and arranged on opposite sides of a central longitudinal axis wherein (i) a first set of the symmetrically configured and arranged cells are jointly inflatable and deflatable, (ii) a second set of the symmetrically configured and arranged cells are jointly inflatable and deflatable, and (iii) the first set of jointly inflatable and deflatable cells are asymmetrically configured and arranged relative to the second set of jointly inflatable and deflatable cells on opposite sides of the central longitudinal axis. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top view of one embodiment of a seating cushion with the cover and an encircling cell removed to facilitate viewing of internal components. 
     FIG. 2 is a schematic view of one embodiment of a control unit for timed inflation and deflation of the cells. 
     FIG. 3 is an end view of a pair of fluidly interconnected cells on a seating cushion. 
     FIG. 4 is a perspective view of one embodiment of a covered seating cushion. 
     FIG. 5 is an exploded perspective view of a platform area; a pair of peripheral cells and an encircling cell. 
     FIG. 6 is a top view of one embodiment of an evaporative cooling system. 
     FIG. 7 is a top view of another embodiment of a seating cushion with the cover and an encircling cell removed to facilitate viewing of internal components. 
     FIG. 8 is a top view of one embodiment of a back support cushion with the cover removed to facilitate viewing of internal components. 
     FIG. 9 is an end view of a pair of fluidly interconnected cells on a back support cushion. 
     FIG. 10 is a perspective view of one embodiment of a covered back support cushion. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION INCLUDING A BEST MODE 
     Nomenclature 
     x Central Longitudinal Axis 
     y Central Latitudinal Axis 
     z Central Transverse Axis 
       10  Seating Cushion 
       11  Top of Seating Cushion 
       12  Bottom of Seating Cushion 
       13  First Side of Seating Cushion 
       14  Second Side of Seating Cushion 
       15  Front End of Seating Cushion 
       16  Back End of Seating Cushion 
       20  Base 
       21  Platform Area 
       30  Cells 
       30   e  Encircling Cells 
       30   p  Peripheral Cells 
       31  First Group of Cells 
       32  Second Group of Cells 
       33  Upper Surface of Cells 
       34  Lower Surface of Cells 
       35  Access Orifice 
       38  Concave Channel 
       39  Void or Cavity 
       40  Connecting Tunnel 
       41  Connecting Tunnels Connecting the First Group of Cells 
       42  Connecting Tunnels Connecting the Second Group of Cells 
       50  Hook and Loop Tape 
       51  First Half of Hook and Loop Tape 
       52  Second Half of Hook and Loop Tape 
       61   d  First Delivery Tube 
       61   r  First Return Tube 
       62   d  Second Delivery Tube 
       62   r  Second Return Tube 
       63  T-Fitting 
       70  Cover 
       71  Top of Cover 
       72  Bottom of Cover 
       73  First Side of Cover 
       74  Second Side of Cover 
       75  Front of Cover 
       76  Back of Cover 
       77  Opening 
       78  Zipper 
       80  Control Box 
       81  Housing 
       82  Power Switch 
       83  Battery 
       84  Recharging Socket 
       85  Recharging Unit 
       86  Pump Timer 
       87  First Cycle Timer 
       88  Second Cycle Timer 
       89  Pressure Switch 
       90  Buzzer 
       91  Air Pump 
       92  Check Valve 
       93  Main Delivery Tube 
       94  First Valve 
       95  Discharge Port 
       96  Second Valve 
       97  Second Discharge Port 
       99  Manual Pump 
       100  Evaporation and Cooling System 
       110  Control Box 
       112  Power Switch 
       113  Battery 
       114  Recharging Socket 
       115  Recharging Unit 
       116  AirPump 
       120  Air Delivery Tube 
       121  Holes 
       200  Back support Cushion 
       220  Base 
       230  Cells 
       231  First Group of Cells 
       232  Second Group of Cells 
       233  Upper Surface of Cells 
       235  Access Orifice 
       240  Connecting Tunnel 
       241  Connecting Tunnels Connecting the First Group of Cells 
       242  Connecting Tunnels Connecting the Second Group of Cells 
       261   d  First Delivery Tube 
       261   r  First Return Tube 
       262   d  Second Delivery Tube 
       262   r  Second Return Tube 
       270  Air Supply Tube 
       280  Cover 
       281  Top of Cover 
       282  Bottom of Cover 
       283  First Side of Cover 
       284  Second Side of Cover 
       285  Front of Cover 
       286  Back of Cover 
       287  Retaining Straps 
       288  Zipper 
     Definitions 
     As utilized herein, including the claims, the phrase “encircling cell” means a cell configured and arranged with an upper surface which defines a completely (100%) or partially (at least 60%) surrounded void or cavity. Encircling cells permit positioning of a protuberance or selected area, such as an ischial tuberosity, within the void or cavity so that the cell while reducing or eliminating pressure can provide support exerted upon the protuberance or selected area positioned within the void or cavity. 
     As utilized herein, including the claims, the phrase “hollow cell” means a cell having a central transversely open cavity. 
     As utilized herein, including the claims, the term “majority” means greater than 50%. 
     As utilized herein, including the claims, the phrase “uninterrupted fluid communication” means an interconnection allowing for the free, unrestrained and uncontrolled conveyance of fluid from one location to another. 
     As utilized herein, including the claims, the phrase “substantially different size or shape” means (i) a volume differential of at least 20%, or (ii) a maximum common volume of less than 80%. 
     As utilized herein, including the claims, the phrase “maximum common volume” is calculated by dividing the greatest volume capable of being occupied by both objects when the objects are permitted to occupy the same three dimensional space, divided by the combined volume of the two objects. 
     Construction 
     Seating Cushion 
     The seating cushion  10  includes a base  20 , cells  30  and a control box  80 . The seating cushion  10  can be used in connection with any type of seating including standard residential and office chairs, airplane seats, vehicle seating, etc., but is particularly suited for use with wheelchairs (not shown). 
     The base  20  is preferably a planar sheet of material having sufficient structural integrity, such as rubber, neoprene, urethane, vinyl, or plastisol. 
     The cells  30  must be constructed from a material having sufficient structural integrity to support an individual in a seated or prone position upon the inflated cells  30 . 
     In addition, the cells  30  must be capable of withstanding repeated inflation and deflation cycles. The cells  30  are preferably constructed of a resilient material such as, but not limited to rubber, neoprene, urethane, vinyl, or plastisol. 
     The cells  30  are connected to a base  20  by any conventional means, including specifically, but not exclusively heat sealing or adhesive bonding. 
     As shown in FIGS. 1 and 7, the cushion  10  preferably includes a pair of laterally spaced encircling cells  30   e  having the same or different shapes. The encircling cells  30   e  include a void or cavity  39  in the upper surface  33 , such as a continuous central passage as shown in FIG. 1 or a sector-shaped cut-out as shown in FIG.  7 . The void or cavity  39  in the encircling cells  30   e  allows the encircling cells  30   e  to support the perimeter of an area or protuberance (not shown) on the posterior (not shown) of a user (not shown), such as an ischial tuberosity (not shown), without directly touching the area or protuberance. Suitable shapes for an encircling cell  30   e  include any of a wide variety of hollows, notched, indented, or otherwise voided, regular or irregular shapes. Such shapes include specifically, but not exclusively, a transversely extending U, a hollow cube, a hollow rectangle, a hollow right cylinder, a hollow frustum of right cone, a torus, a hollow spherical sector, a hollow conical ring, a cube with a concave upper surface, a rectangle with a concave upper surface, a right cylinder with a concave upper surface, a frustum of right cone with a concave upper surface, a side notched cube, a side notched rectangle, a side notched right cylinder, a side notched frustum of right cone, etc. 
     In one embodiment, the encircling cells  30   e  are repositionably attached to the base  20  within a platform area  21  so as to allow repositioning of the encircling cells  30   e  to corresponding with the specific location of a user&#39;s ischial tuberosities (not shown). A particularly suitable means for respositionably attaching the encircling cells  30   e  to the base  20  is with hook and loop tape  50  wherein a first half  51  of the hook and loop tape  50  is secured to the base  20  so as to cover substantially the entire area constituting the platform area  21 , and a second half  52  of the hook and loop tape  50  secured to the lower surface  34  of the encircling cells  30   e . A respositionable pressure sensitive adhesive may also be employed. Other cells  30  may also be repositionably attached to the base  20 . 
     As shown in FIGS. 1 and 7, the cushion  10  also preferably includes peripheral cells  30   p  extending concentrically or radially from each encircling cell  30   e . The peripheral cells  30   p  may have the same or different shapes. As shown in FIG. 1, the cushion  10  can include several rows of peripheral cells  30   p  extending along several different concentric lines so as to define inner, outer and intermediate levels of peripheral cells  30   p.    
     The configuration and arrangement of the cells  30 , including the encircling cells  30   e  and peripheral cells  30   p , facilitates pressure relief in the areas of greatest concern for the development of pressure sores, including the ischial tuberosities, coccyx, and sacrum. 
     The cells  30 , especially the encircling cells  30   e , are preferably symmetrically configured and arranged on opposite sides of a central longitudinal axis x. 
     In one aspect, shown in FIG. 1, only selected cells  30  are equipped with an access orifice  35  and the cells  30  are interconnected by connecting tunnels  40  into individually inflatable and deflatable cell groups (e.g., a first group of cells  31  and a second group of cells  32  with the first group of cells  31  fluidly connected to one another by a plurality of first connecting tunnels  41 , and the second group of cells  32  fluidly connected to one another by a plurality of second connecting tunnels  42 ). 
     In another aspect, shown in FIG. 7, each cell  30  is equipped with an access orifice  35  and the cells  30  are interconnected by tubing into individually inflatable and deflatable cell groups (e.g., a first group of cells  31  and a second group of cells  32  with the first group of cells  31  fluidly connected to one another by a branched first delivery tube  61   d , and the second group of cells  32  fluidly connected to one another by a branched second delivery tube  62   d ). 
     The first  31  and second  32  cell groups are symmetrically or asymmetrically distributed throughout the base  20  so that each cell group can individually support a user (not shown) seated upon the seating cushion  10 . The two encircling cells  30   e  may be placed together in the same cell group or in separate cell groups as desired. In a preferred embodiment, the encircling cells  30   e  are split between the two cell groups with one of the encircling cells  30   e  in the first group  31  and the other encircling cell  30   e  in the second group  32 . 
     The aspect shown in FIG. 7 facilitates last minute customization of cell groupings, including grouping of the encircling cells  30   e , to accommodate the specific needs and desires of a particular user (not shown). The aspect shown in FIG. 7 also permits selected cells  30  to be fluidly disconnected from both the first  31  and second  32  cell groups and connected to a manual pump  99 , such as an inflation bulb, for independent inflation and deflation by the user. 
     As shown in FIG. 3, at least some and desirably all of the peripheral cells  30   p  preferably have an upper surface  33  contoured with a longitudinally extending laterally concave channel  38  designed to match the natural curves of the human body and provide a more comfortable and stable seating area. 
     The base  20  and cells  30  are preferably surrounded with a removable cover  70 . At least the top  71  of the cover  70  should be permeable so that air flowing from the return tubes  61   r  and  62   r  and/or air delivery tube  120  into the cover  70  can flow through the top  71  of the cover  70  and thereby ventilate the areas of contact between a user (not shown) and the cushion  10 . The cover  70  can be constructed from a perforated material but is preferably constructed from a permeable fabric such as cotton or a cotton/polyester blend. If desired the cover  70  can be constructed from a gas permeable moisture impermeable material such as Gortex®. 
     The cover  70  is preferably provided with a zipper  78  so that the cover  70  may be removed and laundered or replaced. An opening  77 , preferably along a seam (not shown) permits passage of the delivery tubes  61   d  and  62   d , return tubes  61   r  and  62   r , and cooling air delivery tube  120  through the cover  70 . 
     A suitable control box  80  is disclosed in U.S. Letters Pat. No. 6,216,299, the disclosure of which is hereby incorporated by reference. Briefly, the control box  80  described in United States Letters Pat. No. 6,216,299 and shown in FIG. 2 includes (i) an air pump  91 , (ii) a battery  83 , (iii) a power switch  82  electrically connected to the battery  83 , (iv) a pump timer  86  electrically connected to the power switch  82  and the air pump  91 , (v) a first cycle timer  87  electrically connected to the power switch  82  and a first valve  94  wherein the first valve  94  is fluidly connected between the air pump  91  and the first group of cells  31 , and (vi) a second cycle timer  88  electrically connected to the power switch  82  and a second valve  96  wherein the second valve  96  is fluidly connected between the air pump  91  and the second group of cells  32 . 
     A check valve  92  is preferably positioned along the main delivery tube  93  between the air pump  91  and the valves  94  and  96  for preventing airflow from reversing and entering the air pump  91  when operation of the air pump  91  is terminated. 
     A differential pressure switch  89  is preferably placed in fluid communication with the main delivery tube  93  downstream from the check valve  92  for detecting fluid pressure within the main delivery tube  93  and thereby detecting fluid pressure within the currently inflated group of cells  31  or  32 . The pressure switch  89  is electrically connected to a suitable device for generating a perceptible signal, such as a buzzer  90  for activating the buzzer  90  and emitting an audible warning when low pressure is detected by the pressure switch  89 . Alternatively, separate pressure switches  89  may be placed in fluid communication with each of the first  31  and second  32  cell groups. 
     The control box  80  allows the user (not shown) to control the amount of fluid pressure within the cells  30  by adjusting the pump timer  86 , which controls the duration of operation of the air pump  91 . The control box  80  also allows the user (not shown) to control the amount of time that each of the first  31  and second  32  cell groups are inflated by adjusting the first cycle timer  87  and second cycle timer  88  respectively. 
     A recharging socket  84  can be provided for electrically connecting the battery  83  to a recharging unit  85  so as to allow recharging of the battery  83 . 
     A housing  81  supports and encloses all of the electrical components of the control box  80 . Support straps (not shown) are preferably attached to the housing  81  for selectively engaging and supporting the housing  81  to a wheelchair (not shown) or other suitable structure. 
     A first delivery tube  61 d fluidly connects the first valve  94  to the first group of cells  31  for delivering pressurized fluid to the first group of cells  31  when air pump  91  is operating and the first valve  94  is open. A second delivery tube  62   d  fluidly connects the second valve  96  to the second group of cells  32  for delivering pressurized fluid to the second group of cells  32  when air pump  91  is operating and the second valve  96  is open. 
     The first cycle timer  87  is adjustable by the user (not shown) and determines the period of time that the first valve  94  is open. The first valve  94  includes a first discharge port  95  that is closed when the first valve  94  is open. The first discharge port  95  opens when the first valve  94  is closed. 
     The second cycle timer  88  is similarly adjustable by the user (not shown) and determines the period of time that the second valve  96  is open. The second valve  96  includes a second discharge port  97  that is closed when the second valve  96  is open. The second discharge port  97  opens when the second valve  96  is closed. 
     A first return tube  61   r  is fluidly connected to the first discharge port  95  of the first valve  94 . A second return tube  62   r  is fluidly connected to the second discharge port  97  of the second valve  96 . A distal end (unnumbered) of each return tube  61   r  and  62   r  is positioned between the cells  30 . The return tubes  61   r  and  62   r  each include a plurality of holes (unnumbered) through the return tube  61   r  and  62   r  over that length of the return tube  61   r  and  62   r  positioned within the cover  70  for the purpose of dispersing fluid received from the respective discharge port  95  and  97  when the respective valve  94  and  96  is closed. The return tubes  61   r  and  62   r  may extend between the cells  30  in any desired configuration to achieve the desired ventilation between the cushion  10  and a user (not shown) seated upon the cushion  10 . 
     Alternating the load bearing responsibility between the first group of cells  31  and the second group of cells  32  alternates the pressure contact points between the user (not shown) and the cushion  10  and thereby helps prevent the formation of pressure sores. 
     Evaporative Cooling System 
     The cushion  10  may optionally be equipped with an active evaporative cooling system  100  which includes a control box  110  and an evaporative cooling air delivery tube  120  for preventing the build-up of heat and moisture between the cushion  10  and user (not shown) seated on the cushion  10 . The control box  110  includes (i) an air pump  116  fluidly connected to the evaporative cooling air delivery tube  120 , (ii) a battery  113 , and (iii) a power switch  112  electrically connected to the air pump  116  and the battery  113 . 
     A recharging socket  114  can be provided for electrically connecting the battery  113  to a recharging unit  115  so as to allow recharging of the battery  113 . 
     The evaporative cooling air delivery tube  120  is fluidly connected to the air pump  116  at one end with the opposite end positioned within the cover  70  between the cells  30 . The evaporative cooling air delivery tube  120  has a plurality of holes  121  over that length of the tube  120  positioned within the cover  70  for the purpose of dispersing air pumped by the air pump  116  into the cover  70  and out through the air permeable top  71  of the cover  70 . 
     Back Support Cushion 
     A back support cushion  200  may optionally be used in conjunction with the seat cushion  10 . The back support cushion  200  includes a base  220 , cells  230  and a control box (not shown). 
     The base  220  is preferably a planar sheet of material having sufficient structural integrity, such as rubber, neoprene, urethane, vinyl, or plastisol. 
     The cells  230  must be constructed from a material having sufficient structural integrity to support the back of a seated individual upon the inflated cells  230 . In addition, the cells  230  must be capable of withstanding repeated inflation and deflation cycles. The cells  230  are preferably constructed of a resilient material such as, but not limited to rubber, neoprene, urethane, vinyl, or plastisol. 
     The cells  230  are connected to a base  220  by any conventional means, including specifically, but not exclusively heat sealing or adhesive bonding. 
     As shown in FIG. 8, the back cushion  200  preferably includes at least two longitudinal columns and three lateral rows of rectangular cells  230 . The cells  230  may be repositionably attached to the base  220  so as to allow customized repositioning of the cells  230 . The configuration and arrangement of the cells  230  provides maximum comfort and support to the back, including the lumbar region of the back. 
     In one aspect, all cells  230  are fluidly interconnected by connection tunnels  240  such that all cells  230  are inflated and deflated together. 
     In another aspect, only selected cells  230  have an access orifice  235  and the cells  230  are interconnected by connection tunnels  240  into a first group of cells  231  and a second group of cells  232  with the first group of cells  231  fluidly connected to one another by first connecting tunnel(s)  241 , and the second group of cells  232  fluidly connected to one another by second connecting tunnel(s)  242 . 
     In yet another aspect, each cell  230  has an access orifice  235  and the cells  230  are interconnected into a first group of cells  231  and a second group of cells  232  with the first group of cells  231  fluidly connected to one another by a branched first delivery tube  261   d , and the second group of cells  232  fluidly connected to one another by a branched second delivery tube  262   d.    
     When the cells  230  are grouped into first  231  and second  232  cell groups, the first  231  and second  232  cell groups are distributed throughout the base  220  so that each group can individually comfortably support the back (not shown) of a user (not shown) resting upon the cushion  200 . 
     The aspect in which each cell  230  has an access orifice  235  facilitates customization of cell grouping in order to suit the particular needs and desired of a specific user. 
     At least some, and desirably all, of the cells  230  preferably have an upper surface  233  contoured to match the natural shape and curves of the human body and thereby provide a more comfortable and stable back support. 
     The base  220  and cells  230  are preferably surrounded with a removable cover  280 . At least the front  285  of the cover  280  should be permeable so that air flowing from the return tubes  261   r  and  262   r  and/or evaporative cooling air supply tube  270  into the cover  280  can flow through the cover  280  and thereby ventilate the areas of contact between the cushion  200  and a user (not shown) resting upon the back cushion  200 . The cover  280  can be constructed from a perforated material but is preferably constructed from a permeable fabric such as cotton or a cotton/polyester blend. The cover  280  can be constructed from a gas permeable and moisture impermeable material such as Gortex®. 
     The cover  280  is preferably provided with a zipper  288  so that the cover  280  may be removed and laundered or replaced. An open area (not shown), preferably along a seam (not shown) permits passage of the delivery tubes  261   d  and  262   d , return tubes  261   r  and  262   r , and cooling air supply tube  270  through the cover  280 . 
     The cover  280  preferably includes straps  287  for securing the back support cushion  200  to the back (not shown) of a chair (not shown) 
     Those control boxes  80  described as suitable for use in connection with the seating cushion  10  are also suitable for use with the back support cushion  200 . 
     The fluid connection system described as suitable for use in connection with the seating cushion  10  for the delivery and return of pressurizing fluid to the cells  30  is also suitable for use with the back support cushion  200 . 
     The evaporative cooling system  100  described as suitable for use in connection with the seating cushion  10  for the delivery of evaporative cooling air to the cushion  10  is also suitable for use with the back support cushion  200 . 
     Use 
     A user (not shown) adjusts the pump timer  86  to the desired amount of time depending upon the weight and personal preference of the user (not shown). Generally, pumping time should increase as the user&#39;s weight increases. The user (not shown) then adjusts the first cycle timer  87  and the second cycle timer  88  to the desired time intervals between inflation and deflation cycles. The user then positions the base  20  of the seat cushion  10  upon the seat (not shown) of the chair (not shown) and connects the control box  80  to the chair (not shown). 
     To initiate cycling, the user (not shown) closes the power switch  82  and thereby provides electrical power to the pump timer  86  and the first cycle timer  87 . The air pump  91  will operate for the period of time (T 1 ) specified by the pump timer  86  while the first cycle timer  87  opens the first valve  94  for a period of time (T 2 ) specified by the first cycle timer  87  so as to allow air pumped by the air pump  91  to enter and inflate the first group of cells  31 . When time period T 1  is reached, operation of the air pump  91  is terminated. During the time the first valve  94  is open, the second valve  96  should be closed. 
     When time period T 2  is reached, the first valve  94  is closed. Closing of the first valve  94  causes the first discharge port  95  to open and release the air pressure from within the first group of cells  31  through the now open first discharge port  95  and into the first return tube  61   r  where it is dissipated through holes (unnumbered) so as to dry and cool the user&#39;s body in contact with the cushion  10 . 
     The air pump  91  then operates again for the period of time (T 1 ) specified by the pump timer  86  while the second cycle timer  88  opens the second valve  96  for the period of time (T 3 ) specified by the second cycle timer  88  so as to allow air pumped by the air pump  91  to enter and inflate the second group of cells  32 . When time period T 1  is reached, operation of the air pump  91  is terminated. During the time the second valve  96  is open, the first valve  94  should be closed. 
     When time period (T 3 ) is reached, the second valve  96  is closed. Closing of the second valve  96  causes the second discharge port  97  to open and releases the air pressure from within the second group of cells  32  through the second discharge port  97  and into the second return tube  62   r  where it is dissipated through holes (unnumbered) so as to again dry and cool the user&#39;s body in contact with the cushion  10 . 
     The process is repeated until the power switch  82  is opened. 
     When a manual pump  99  is connected to one or more of the cells  30 , the user may inflate and deflate those cells  30  as desired. 
     The same process applies to use of the back cushion  200 .