Abstract:
A stand for a medical fluid treatment, a system for supporting multi-chamber medical fluid bags and a method for testing whether the multi-chamber bags have been preset properly for therapy are provided. In one embodiment a multi-section stand is provided that is folded in a number of places to produce a structure upon which fluid from a properly preset solution bag flows readily to a patient, but upon which a dual-chamber bag that has not been modified properly for treatment collapses, folds or falls to a position providing visual indication that the chamber seal needs to be released or opened.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention generally relates to dialysis systems. More specifically, the present invention relates to an apparatus and method for coordinating and testing multiple dialysis fluid chamber bags.  
         [0002]     Due to disease, injury or other causes, a person&#39;s renal system can fail. In renal failure of any cause, there are several physiological derangements. The balance of water, minerals and the excretion of daily metabolic load is no longer possible in renal failure. During renal failure, toxic end products of nitrogen metabolism (urea, creatinine, uric acid, and others) can accumulate in blood and tissues.  
         [0003]     Kidney failure and reduced kidney function have been treated with dialysis. Dialysis removes waste, toxins and excess water from the body that would otherwise have been removed by normal functioning kidneys. Dialysis treatment for replacement of kidney functions is critical to many people because the treatment is life sustaining. One who has failed kidneys could not continue to live without replacing at least the filtration functions of the kidneys.  
         [0004]     Hemodialysis and peritoneal dialysis are two types of dialysis therapies commonly used to treat loss of kidney function. Hemodialysis treatment utilizes the patient&#39;s blood to remove waste, toxins and excess water from the patient. The patient is connected to a hemodialysis machine and the patient&#39;s blood is pumped through the machine. Catheters are inserted into the patient&#39;s veins and arteries to connect the blood flow to and from the hemodialysis machine. As blood passes through a dialyzer in the hemodialysis machine, the dialyzer removes the waste, toxins and excess water from the patient&#39;s blood and returns the blood back to the patient. A large amount of dialysate, for example about 120 liters, is used to dialyze the blood during a single hemodialysis therapy. The spent dialysate is then discarded. Hemodialysis treatment lasts several hours and is generally performed in a treatment center about three or four times per week.  
         [0005]     Peritoneal dialysis utilizes a dialysis solution or “dialysate”, which is infused into a patient&#39;s peritoneal cavity through a catheter implanted in the cavity. The dialysate contacts the patient&#39;s peritoneal membrane in the peritoneal cavity. Waste, toxins and excess water pass from the patient&#39;s bloodstream through the peritoneal membrane and into the dialysate. The transfer of waste, toxins, and water from the bloodstream into the dialysate occurs due to diffusion and osmosis, i.e., an osmotic gradient occurs across the membrane. The spent dialysate drains from the patient&#39;s peritoneal cavity and removes the waste, toxins and excess water from the patient. This cycle is repeated.  
         [0006]     There are various types of peritoneal dialysis therapies, including continuous ambulatory peritoneal dialysis (“CAPD”), automated peritoneal dialysis and continuous flow peritoneal dialysis. CAPD is a manual dialysis treatment, in which the patient connects an implanted catheter to a drain and allows a spent dialysate fluid to drain from the peritoneal cavity. The patient then connects the catheter to a bag of fresh dialysate and manually infuses fresh dialysate through the catheter and into the patient&#39;s peritoneal cavity. The patient disconnects the catheter from the fresh dialysate bag and allows the dialysate to dwell within the cavity to transfer waste, toxins and excess water from the patient&#39;s bloodstream to the dialysate solution. After a dwell period, the patient repeats the manual dialysis procedure.  
         [0007]     In CAPD the patient performs several drain, fill, and dwell cycles during the day, for example, about four times per day. Each treatment cycle typically takes about an hour. Manual peritoneal dialysis performed by the patient requires a significant amount of time and effort from the patient.  
         [0008]     Automated peritoneal dialysis (“APD”) is similar to CAPD in that the dialysis treatment includes a drain, fill, and dwell cycle. APD machines, however, automatically perform three to four cycles of peritoneal dialysis treatment, typically overnight while the patient sleeps. The APD machines are fluidly connected to a catheter implanted in the patient. The APD machines are also fluidly connected to a source or bag of fresh dialysate and to a fluid drain.  
         [0009]     The APD machines pump fresh dialysate from the dialysate source, through the catheter, into the patient&#39;s peritoneal cavity and allow the dialysate to dwell within the cavity so that the transfer of waste, toxins and excess water from the patient&#39;s bloodstream to the dialysate solution can take place. The APD machines then pump spent dialysate from the peritoneal cavity, though the catheter, to the drain. APD machines are typically computer controlled so that the dialysis treatment occurs automatically when the patient is connected to the dialysis machine, for example, when the patient sleeps. That is, the APD systems automatically and sequentially pump fluid into the peritoneal cavity, allow for a dwell, pump fluid out of the peritoneal cavity and repeat the procedure.  
         [0010]     As with the manual process, several drain, fill, and dwell cycles will occur during APD. A “last fill” is typically used at the end of APD, which remains in the peritoneal cavity of the patient when the patient disconnects from the dialysis machine for the day. APD frees the patient from having to manually performing the drain, dwell, and fill steps.  
         [0011]     For each of the above-described dialysis therapies, each of the associated cycles typically consumes a separate bag of solution or dialysate. Over the course of therapy, multiple bags of such solution are used. In many instances, solution bags with a single chamber or pouch are used. In such a case, the solution is completely premixed, sterilized and ready to use. In other instances, the bags include multiple chambers that divide a base solution from an additive. With multi-chamber bags, the patient must break a seal to enable the additive to run to the base solution. It happens sometimes that the patient does not properly open the seal or forgets to open the seal completely. In such a case, therapy does not take place properly.  
         [0012]     It is therefore desirable to have a ready apparatus to organize and support multiple solutions bags sequentially or simultaneously.  
         [0013]     It is also desirable to have an apparatus that ensures that the patient has properly preset or opened a multi-chamber bag for use.  
       SUMMARY OF THE INVENTION  
       [0014]     The present invention includes an apparatus and method for holding or supporting medical fluid therapy supply bags and for ensuring that if a multiple or dual chamber supply bag is used, that the bag has been properly preset for therapy. Multiple chamber or dual chamber supply bags are known and popular medical fluid supply devices. The bags house different components of an overall solution that is delivered to a patient for therapy. For example, a dual chamber dialysis fluid or dialysate bag can include one chamber with sterile fluid, such as sterile water with electrolytes, wherein a separate chamber includes an additive such as dextrose. The components are stored separately until time of use. At that time the patient or caregiver is required to break a seal, such as the Easy to Peal Seal™ of dual chamber bags provided by the assignee of the present invention. It is important that such opening of the seal is preformed prior to therapy. The present invention provides not only a stand that supports the supply bags at an angle suitable for delivering the overall solution throughout therapy, the stand also provides an apparatus and method for visually indicating to the patient or caregiver whether the seal has been opened properly or not.  
         [0015]     In one aspect of the present invention, a supply bag stand is provided that has a seat portion and a back portion. The seat portion and back portion are positioned at an angle with respect to one another. That angle is well-suited for enabling medical fluid, such as dialysate, to flow from the bag to the medical fluid apparatus, such as an APD machine. The angle is also set so that if the seal between two chambers of a multi-chamber bag has not been properly opened, a chamber that has been propped or positioned up against the back of the stand falls over onto a chamber that has been set onto the seat portion of the stand. That action provides a readily seen visual cue that the solution bag is not properly preset for therapy. On the other hand, if the seal between the dual chambers has been opened properly, the bag remains in position, so that the first chamber remains propped or positioned against the back portion, while the other chamber remains situated on the seat portion, enabling the properly mixed solution to flow to the patient.  
         [0016]     In one embodiment, the chamber that rests on the seat portion of the stand has an outlet tube or stem that connects fluidly to the medical fluid therapy apparatus. The present invention is expressly not limited to dialysis systems. The present invention is however well-suited for renal failure therapy treatment as well as congestive heart failure treatment. The medical fluid apparatus can therefore be a CAPD apparatus APD apparatus, hemofiltration apparatus, hemodiafiltration apparatus or any combination thereof.  
         [0017]     It is contemplated to provide the stand in a number of different ways using different components. One preferred apparatus includes a series of sections or boards that are hinged sequentially together. In particular, in one embodiment the stand includes two inner boards and two outer boards, wherein the outer boards are hingedly connected to the inner boards. The inner boards are then separated by a middle portion, which can be flexible, semi-flexible, semi-rigid or rigid. To create a stand, the sections or boards are folded to create a sturdy structure with the back portion set at an angle with respect to the seat portion. The back portion includes the middle portion separating the inner sections. The patient or caregiver sets the multi-chamber solution bag on the stand constructed from the multiple folded sections described above, so that one bag rests on the seat portion, while the other bag rests on the middle, e.g., flexible portion of the back. That flexible portion is movable so that if the seal between the chambers of the bag is not broken, fluid in the upper section is pulled downward by gravity, causing the upper chamber to fall down onto the lower chamber.  
         [0018]     The foldable boards or rigid sections are plastic, metal, wood or composite structures that are coated in one embodiment with a flexible water impermeable coating, such as a thin plastic coating. The plastic coating also creates hinge seams between the inner and outer sections as well as between the middle portion and the inner boards. Such material and configuration is cost effective, light weight, sturdy, easy to clean and safe.  
         [0019]     In another embodiment, two rigid pieces are hinged together, such that the back portion folds away from the seat portion to create the desired angle between the two members. The seat portion is also angled slightly relative to a horizontal plane, so that fluid flows properly out of the supply bag to the patient. This alternative embodiment may or may not use a flexible backing section or piece described above for the folded embodiment. Nevertheless, the angle created between the two members in this alternative embodiment is sufficient so that if the seal is not properly opened, the upper fluid chamber falls down onto the lower fluid chamber and thereby provides visual indication that the bag is not properly preset for therapy. If, however, the seal has been opened, the angle of the alternative apparatus allows the fluid from the upper chamber to flow through the lower chamber, combining with the fluid in same to create an overall mixture that is delivered to the patient. The alternative stand is likewise made of one or more materials selected from the group consisting of plastic, metal, wood, a composite material and any combination thereof.  
         [0020]     In any of the embodiments described herein, the stand can be sized to hold a single solution bag or multiple solution bags. If the stand is sized to hold multiple solution bags, each of those bags can be tested sequentially or simultaneously to ensure that the seal separating dual or multiple chambers is opened properly prior to therapy. Additionally, if the solution bags have not been properly preset for therapy, the stand supporting the multiple solution bags provides visual indication of same, for one or more or all of the supply bags. If the bags have been properly preset for therapy, the stand enables fluid to flow as designed through the multipe chambers of each multi-chamber bag.  
         [0021]     It is therefore an advantage of the present invention to provide a supply bag medical stand that enables fluid from a bag set thereon to flow properly to a medical fluid therapy device.  
         [0022]     It is also an advantage of the present invention to provide a supply bag stand that is operable with multiple renal failure therapy apparatuses, such as a CAPD apparatus, APD apparatus, hemodialysis apparatus, hemofiltration apparatus, hemodiafiltration apparatus and any combination thereof.  
         [0023]     It is a further advantage of the present invention to provide a stand that indicates when one or more bags set thereon has not been properly preset for therapy.  
         [0024]     Further still, it is an advantage of the present invention to provide a stand operable so that when one or more solution bags set thereon has not been properly opened to allow fluid to flow from one chamber to another, such failure is visually indicated.  
         [0025]     Moreover, it is an advantage of the present invention to provide a medical fluid supply bag stand that enables fluid to: (i) flow properly from one chamber through another chamber; (ii) mix with fluid in the other chamber; and (iii) flow as a mixed fluid properly to the patient.  
         [0026]     Still further, it is an advantage of the present invention to provide a lightweight, compact, safe, water impermeable, sturdy and cost effective medical fluid supply bag stand.  
         [0027]     Yet another advantage of the present invention is to provide a medical fluid supply bag stand that is readily assembled and disassembled.  
         [0028]     Additional features and advantages of the present invention are described in, and will be apparent from, the following Detailed Description of the Invention and the figures. 
     
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0029]      FIG. 1  illustrates one embodiment of the stand of the present invention shown in the flat, with multiple foldable sections.  
         [0030]      FIG. 2  illustrates the stand of  FIG. 1  at one point in the assembly thereof.  
         [0031]      FIG. 3  illustrates the stand of  FIG. 1  in a second point in the assembly thereof.  
         [0032]      FIG. 4  illustrates the assembled stand of  FIG. 1  placed on a horizontal surface.  
         [0033]      FIGS. 5 and 6  illustrate the stand test method and visual indication provided when the multiple chamber solution bag has not been opened properly.  
         [0034]      FIGS. 7 and 8  illustrate the stand test method and the flow of fluid from one chamber to another and from the dual chambers to the patient when the multiple chamber bag has been properly preset for therapy.  
         [0035]      FIG. 9  illustrates an alternative embodiment of the stand apparatus of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0036]     The present invention includes an apparatus and method for supporting one or more medical fluid supply bags during treatment as well as testing such bags to determine whether a seal or flow restriction has been opened to allow fluids from one chamber to enter a second chamber to thereafter provide a ready therapy fluid for treatment. The stand and method of testing described herein apply to any medical fluid treatment using supply bags having multiple chambers, wherein fluids or constituents within the chambers are mixed at the time of therapy. In particular, the stand and test method are well suited for renal failure or congestive heart failure treatment. For example, the stand and test method are well suited for CAPD, APD, hemodialysis, hemofiltration, hemodiofiltration and any combination thereof.  
         [0037]     Referring now to the drawings and in particular to FIGS.  1  to  4 , one embodiment of the supply bag stand of the present invention is illustrated by stand  10 . Stand  10  is shown in various stages of formation in FIGS.  1  to  4 .  FIG. 1  illustrates stand  10  flattened out and before the stand is folded. As illustrated, stand  10  includes two inner sections or boards  12  and  14  and two outer sections or outer boards  16  and  18 . Sections or boards  12  to  18  are relatively rigid. A flexible, sheet-like or cloth-like central section  20  is provided between inner sections  12  and  14 . In alternative embodiments, central section  20  is semi-flexible, semi-rigid or rigid. Outer section  16  and inner section  12  are separated by hinge seam  22 . Inner section  14  and outer section  18  are separated by hinge seam  24 . Hinge seams  22  and  24  enable outer sections  16  and  18  to rotate in either direction relative to inner sections  12  and  14 . Thus outer sections  16  and  18  can be folded in either direction and to any suitable angle relative to inner sections  12  and  14 , respectively.  
         [0038]     Inner sections  12  and  14  can both in turn rotate or bend in either direction and to any suitable angle with respect to central flexible, semi-rigid or rigid portion  20 . It should be appreciated therefore that relatively rigid sections  16 ,  12 ,  14  and  18  and the, e.g., flexible, central portion  20  can be bent in a myriad of combinations of ways.  
         [0039]     The relatively rigid portions  12 ,  14 ,  16 , and  18  in one embodiment include semi-rigid or rigid pieces that are covered with and connected by a thin coating. In one embodiment, the inside semi-rigid or rigid structures are made of plastic, pasteboard, wood, metal, a composite material and any combination thereof. The thin outer coating in one embodiment is a strong, water resistant and easily cleaned polymer material, such as vinyl. Alternatively, the outer coating is soft cloth, a woven material or other strong and water resistant or impermeable fabric or material. The outer coating material is also crimped, heat sealed or otherwise bonded together to form the hinge seams  22  and  24 . Similar seals, crimps or other type of connections are also made along the inside edges of inner sections  12  and  14  to separate same from central portion  20 . Central portion  20  can be comprised of one or more plies of the outer coating or include alternatively a semi-flexible, semi-rigid or rigid inside structure, such as that used for portions  12 ,  14 ,  16  and  18 .  
         [0040]     As seen in  FIG. 1 , sections  12  through  20  each have the same or substantially same width w in one embodiment. Width w can be varied to support one or a plurality of supply bags. Such support is shown in detail below.  FIG. 1  also shows that the sections  12  to  20  have varying lengths l 12  to l 20 . Lengths l 12  to l 20  are set so that when corresponding sections  12  to  20  are bent to form stand  10 , the proper or desired structure having the sections set at the desired angles is formed.  
         [0041]     Referring now to  FIGS. 2 and 3 , stand  10 , shown in partially bent forms, illustrates how the stand is formed from the flat shown in  FIG. 1 .  FIGS. 2 and 3  show that inner section  12  and outer sections  16  and  18  are bent to form a base or seat portion of stand  10 , while flexible central portion  20  and inner section  14  are bent to form the back or side portion of stand  10 . In an alternative embodiment, portion  20  and inner section  14  are adhered or otherwise fastened together. As seen in  FIGS. 2 and 3 , outer section  16  is bent downward from inner section  12  around the end of outer section  18 , which is bent towards seam  22  with respect to inner portion  14 . Outer portion  18  is bent as illustrated along hinge seam  24 .  
         [0042]     In one embodiment, the weight of rigid boards  12 ,  14 ,  16  and  18  as well as the flexible portion  20  is enough to hold the structure in place. Alternatively, fasteners such as snaps, Velcro™ fasteners, tabs and/or slits are provided on outer portions  16  and  18  to hold the finished structure shown in  FIG. 4  in place. Section  18  abutted against hinge seam  22  between sections  12  and  16  and the lengths l 12 , l 14  and l 20  collectively cause board  14  to be positioned at least somewhat vertically, so that board  14  and central portion  20  form a back or side wall at an angle α shown in  FIGS. 2 through 4 .  
         [0043]      FIG. 4  shows that the completed structure  10  is placed by a person  26  onto a horizontal surface  28 , such as a table, night stand, floor or other substantially horizontal structure. Once the formed stand  10  is placed onto the flat surface  28 , the stand is ready for use. It should be appreciated that not only does angle α exist between inner section  12  and central flexible portion  20 , a second angle β is formed between inner section  12  and outer section  18 . As seen in  FIG. 4 , outer section  18  and mating section  16  are substantially parallel to and indeed lay on top of horizontal surface  28 . Angle β is provided so that when one or more solution bag is properly preset, e.g., the seal of the dual chamber bag is opened, the fluid flows from the bag due to the slight downward grade of inner section  12  from angle β towards the horizontal surface  28 .  
         [0044]     Referring now to FIGS.  5  to  8 , one embodiment for performing the supply bag test procedure of the present invention is illustrated using stand  10  as previously described. FIGS.  5  to  8  each illustrate a multi-chamber or dual chamber bag  30 . Bag  30  includes lower chamber  32  and upper chamber  34 , which are separated via a seal or removable partition  36 . In one embodiment, lower chamber  32  holds the main supply of medical fluid and upper chamber  34  holds an additive, which for any suitable purpose is advantageously kept separate from the main fluid in chamber  32  until use. To that end, multiple additive chambers, such as chamber  34  can be provided, wherein each such chamber holds a separate additive, which is advantageously kept separate from the main fluid within chamber  32  and from the other additives in other additive chambers  34 . It should be appreciated however that dual chamber or multi-chamber supply bag  30  in an alternative embodiment is configured so that the main portion or base solution is kept in upper chamber  34 , while an additive is kept in lower chamber  32 .  
         [0045]     In one preferred embodiment, dual chamber bag  30  holds the components of a dialysis solution or dialysate, which is used for peritoneal dialysis, hemodialysis, hemofiltration or hemodiafiltration. In such a case, lower chamber  32  can hold the base liquid portion of the dialysate, which is largely sterile water plus electrolytes, such as potassium, calcium, sodium, chloride and the like. Upper chamber  34  holds an additive, such as dextrose, one or more of the above electrolytes, an NaCI powder or concentrate and the like, which is advantageously kept separate from the base fluid in chamber  32 . Chamber  34  can alternatively hold any desirable type of additive, which can be in solid particle form, liquid form, concentrate form or any other form in which material can flow from chamber  34  to chamber  32  due at least in part to the force of gravity.  
         [0046]      FIGS. 5 and 6  illustrate the test sequence in which seal  36  has not been opened or has not been opened properly. In  FIG. 5 , patient or operator  26  places bag  30  on stand  10  as illustrated so that lower chamber  32  sets and rests on inner section  12  of stand  10 , while upper chamber  34  sets or rests on central, e.g., flexible, portion  20 . In an embodiment, section  12  and portion  20  will both move slightly due to the weight of the liquid inside lower chamber  32  and upper chamber  34 . Relatively rigid section  12  will pivot slightly about hinge seam  22  and may also flex or bow slightly in the middle. Flexible portion  20  may also pivot slightly about the seam connecting portion  20  to inner portion  14 . The flexible material will also move to conform with the movement of fluid inside upper chamber  34 . The angle a between inner rigid section  12  and flexible section  20  may also change slightly.  
         [0047]      FIG. 6  illustrates that angle a and the angle of inner portion  14  with respect to the horizontal surface  28  are preset via the formation of stand  10  so that if seal  36  is not opened or not opened properly, the weight of fluid within upper chamber  34  causes the upper chamber to fall forward or tip about the axis of seal  36  onto lower chamber  32 . Such action is a distinct visual cue that is likely to be noticed by patient or operator  26 . Indeed, because the patient or operator must connect connector  40  located at the end of stem  38  to the medical fluid apparatus, it would be highly unlikely that the patient or operator would not notice the upper chamber  34  laying on lower chamber  32 . Therefore, the configuration of stand  10  provides an effective visual test and tool for the patient or operator to ensure that the multi-chamber or dual chamber bag  30  is properly preset before therapy.  
         [0048]      FIGS. 7 and 8  illustrate the test outcome when seal  36  has been opened properly. In such a case, fluid such as additive fluid, flows from upper chamber  34 , through the opened seal  36 , into lower chamber  32  and mixes with the fluid therein. Thereafter, the properly mixed fluid, such as dialysis fluid, flows through stem  38  and connector  40  to the medical fluid therapy apparatus. As discussed above, the angle β between inner section  12  and outer section  18 /surface  28  enables the fluids mixed from chamber  34  and chamber  32  to flow smoothly out of stem  38 , connector  40  into the medical fluid therapy device.  
         [0049]     Since the fluid in  FIGS. 7 and 8  is able to flow from upper chamber  34  to lower chamber  32 , the weight of fluid in upper chamber  34  does not cause the upper chamber to fall or fold over onto lower chamber  32 . Instead, upper chamber  34  is seen to shrink or decrease in fluid volume. When seal  36  is properly opened, stand  10  operates to hold chambers  32  and  34  of bag  30  in place properly throughout therapy. After therapy, stand  10  is folded conveniently into a flat structure that is easily stored and consumes little space. Stand  10  in at least certain embodiments is also collapsible, allowing energy from a collision, for example by a running or falling child, to be absorbed through such collapse, reducing the likelihood of harm or injury from the collision.  
         [0050]     As discussed above, stand  10  may have a width w so that multiple dual chamber bags  30  can be placed thereon. The test provided by stand  10  would therefore be performed on each of the multiple chamber bags  30 . That is, any multi-chamber bag on stand  10  that is not properly opened or preset for therapy, fails the test as seen when its upper chamber  34  falls onto its lower chamber  32 . It should therefore be appreciated that the test provided by stand  10  of the present invention can test a plurality of multi-chamber bags at once.  
         [0051]     Stand  10  in one embodiment also displays graphical and/or textual instructions to: (i) fold stand  10  properly; and (ii) explain the dual or multi-bag test procedure. Those same instructions can be provided on bag  30  for operation with stand  10 .  
         [0052]      FIG. 9  illustrates an alterative embodiment for the stand of the present invention. Alternative stand  50  includes a seat portion  52  and a back or rear portion  54 . In one embodiment, both seat  52  and back  54  are single pieces of formed plastic, paste board, metal, composite material or any combination thereof. Seat  52  and back  54  can also have a thin water impermeable coating, such as a plastic, e.g., vinyl, coating.  
         [0053]     As illustrated in  FIG. 9 , seat  52  is angled at angle β with respect to the horizontal surface on which stand  50  is placed. In use, back  54  is rotated up from seat  52  to the desired angle α for performing the test described above. Stand  50 : (i) enables proper flow; (ii) tests one or more multi-chamber solution bags (iii) and performs each of the functions described above for stand  10 . That is, angles α and β are selected so that the weight of additive or fluid in an upper chamber causes the upper chamber to tip over onto lower chamber if the seal between chambers is not opened properly.  
         [0054]     In the illustrated embodiment, seat  52  defines or includes sides  56 . Sides  56  each define an aperture  58 . A hinge pin or hinge device  60  is inserted through aperture  58  to a mating aperture defined by back  54 . Back  54  is thereby hingedly connected to side  56  and seat  52 . A stop, not illustrated, can be provided so that seat  54  is opened automatically to the desired angle α. That stop in one embodiment is adjustable to fine tune the setting of angle α.  
         [0055]     It should be appreciated that those of skill in the art can develop other methods and apparatus for hingedly connecting back  54  to seat  52 . For example, it is possible to place a plurality of detents on sides  56  so that back  54  can be rotated and held at multiple angles for angle α. In any case, when stand  50  is not in use, back  54  folds conveniently into seat  52  and stand  50  is readily stored away as a flat item. Stand  50  can also be provided with suitable instructional graphics and/or indicia.  
         [0056]     It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.