Abstract:
A mask assembly for a patient includes a frame having a lateral flange portion with at least a first hole therethrough. The mask assembly further includes a cushion having a lateral flange portion with at least a second hole therethrough. In addition, the mask assembly includes a cushion clip having a lateral flange with at least one rod that passes through the first and second holes, the rod having a distal end that is secured to the frame when the rod passes through the first and second holes, to thereby sandwich the cushion flange between the flanges of the frame and the cushion clip.

Description:
CROSS-REFERENCE TO APPLICATIONS 
       [0001]    This application is a continuation of U.S. application Ser. No. 13/110,281, filed May 18, 2011, now allowed, which is a divisional of U.S. application Ser. No. 10/585,091, filed Jun. 30, 2006, now U.S. Pat. No. 7,967,013, which is the U.S. national phase of International Application No. PCT/AU2004/001813, filed Dec. 22, 2004 which designated the U.S. and claims priority to U.S. Provisional Application Nos. 60/533,229, filed Dec. 31, 2003, 60/571,488, filed May 17, 2004, 60/588,341, filed Jul. 16, 2004, and 60/619,022, filed Oct. 18, 2004, and International Application No. PCT/AU2004/001760, filed Dec. 15, 2004, each of which is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a disposable mask system for use with patients, e.g., adult patients, for the treatment of obstructive sleep apnea (OSA) or the provision of non-invasive positive pressure ventilation (NIPPY) support using continuous positive airway pressure (CPAP), bi-level, or other pressure support ventilators. The mask is intended for single patient, short-term use having a life span, e.g., of about 7-14 days. Preferably, the mask is only usable for up to 7 days. 
         [0004]    2. Description of Related Art 
         [0005]    ResMed&#39;s Mirage® Disposable Full Face mask is formed of a frame with a double wall silicone cushion. The cushion, elbow, and/or vent components can be disassembled from the frame. While this mask performs strongly for seal and comfort, it may not display characteristics that are most amenable for hospital and clinical use, which can differ from the characteristics most suitable for home or other uses. 
         [0006]    Another related art disposable mask is ResMed&#39;s Disposable Nasal Mask® which has a PVC bubble cushion and a styrene frame. The Image3 Disposable Full Face Mask from Respironics has a frame and a silicone cushion. Yet another full face disposable mask is the Respironics Spectrum Disposable Full Face Mask that has a single PVC cushion and a frame. The Med Series 2100 Disposable Full Face Mask has a PVC frame and a foam cushion. Still another mask is the “Performa Trak,” a single use full face mask from Respironics. 
         [0007]    These related art masks do not provide fully adequate and/or optimum solutions for use of mask systems in a hospital or clinical environment. For example, these masks exhibit one or more properties that are typically associated with re-useable masks. Therefore, these masks can be accidentally re-used in a manner that could be dangerous to the patient, e.g., the risk of spread of germs, etc. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    One aspect of the invention is to provide a mask system which is at least partially capable of overcoming the problems of the related art. 
         [0009]    Another aspect of the invention is to provide a disposable mask which has a useful life of either a single use or can be used over a short period of time, e.g., 7-10 days or more. Preferably, the mask can be used only up to 7 days. 
         [0010]    Another aspect of the invention is to provide a mask which provides an indication, e.g., a visual indication, that the mask has been used once, more than once or more than the recommended number of times or period of time. 
         [0011]    Yet another aspect of the invention is to provide a mask assembly which is difficult to disassemble without breaking, thereby discouraging multiple use and preventing removal of safety components such as an anti-asphyxia valve. 
         [0012]    Still another aspect of the invention is to provide a mask which is disposable and/or which satisfies the needs of the clinical or hospital environment, which often differ from the needs of a mask used in a home environment. 
         [0013]    In another aspect, the mask is designed to be fitted by a clinician or nurse. 
         [0014]    Another aspect of the invention is to provide a low cost mask with high differentiation between disposable and reusable products, in terms of functionality, aesthetics and/or durability. 
         [0015]    These and other aspects of the present invention are described in or apparent from the following description of preferred embodiments. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a perspective view from the front left side illustrating a first preferred embodiment of the present invention; 
           [0017]      FIG. 2  is a rear view thereof; 
           [0018]      FIG. 3  is a front perspective exploded view of a portion of the assembly shown in  FIG. 1 ; 
           [0019]      FIG. 4  is a rear perspective exploded view of a portion of the assembly shown in  FIG. 1 ; 
           [0020]      FIG. 5  is a bottom view of the mask assembly shown in  FIG. 1 ; 
           [0021]      FIG. 6  is a top view thereof; 
           [0022]      FIG. 7  is a right side view thereof; 
           [0023]      FIG. 8  is a perspective view of a frame according to an embodiment of the present invention; 
           [0024]      FIG. 9  is a rear view thereof; 
           [0025]      FIG. 10  is a top view thereof; 
           [0026]      FIG. 11  is a bottom view thereof; 
           [0027]      FIG. 12  is a side view thereof; 
           [0028]      FIG. 12A  is a perspective view of a frame according to another embodiment of the present invention; 
           [0029]      FIG. 13  is a front perspective view of a cushion according to the present invention; 
           [0030]      FIG. 14  is a front view thereof; 
           [0031]      FIG. 15  is a rear view thereof; 
           [0032]      FIG. 16  is a rear perspective view of a cushion clip according to the present invention; 
           [0033]      FIG. 17  is a side view thereof; 
           [0034]      FIG. 18  is a partial exploded cross-sectional view showing assembly of the frame, cushion and cushion clip; 
           [0035]      FIG. 19  is an assembled partial cross-sectional view thereof; 
           [0036]      FIG. 20  is a partial exploded cross-sectional perspective view like that shown in  FIG. 18 ; 
           [0037]      FIG. 21  is an exploded perspective view of a swivel elbow assembly according to the present invention; 
           [0038]      FIG. 22  is an assembled view thereof; 
           [0039]      FIG. 23  is a cross-sectional view thereof; 
           [0040]      FIG. 23A  is an enlarged detail view of a portion of  FIG. 23 ; 
           [0041]      FIG. 23B  is a perspective and cross-sectional view of an elbow according to an embodiment of the invention; 
           [0042]      FIG. 24  is a rear perspective view of a swivel elbow according to an embodiment of the present invention; 
           [0043]      FIG. 25  is a front perspective view thereof; 
           [0044]      FIG. 26  is a rear view thereof; 
           [0045]      FIG. 27  is a bottom view thereof; 
           [0046]      FIG. 28  is a side view thereof; 
           [0047]      FIG. 28A  illustrates a perspective view of a swivel elbow according to another embodiment of the present invention; 
           [0048]      FIGS. 28A-1-28A-2  illustrate views of an elbow according to still another embodiment of the present invention; 
           [0049]      FIGS. 28B-28C  illustrate views of an elbow according to an alternative embodiment of the present invention; 
           [0050]      FIGS. 28D-28H  illustrate views of an elbow according to yet another embodiment of the present invention; 
           [0051]      FIG. 29  is a front perspective view of an anti-asphyxia valve membrane according to the present invention; 
           [0052]      FIG. 30  is a front view thereof; 
           [0053]      FIG. 31  is a side view thereof; 
           [0054]      FIGS. 31 -A to  31 -I illustrate a mask assembly, elbow, swivel and/or anti-asphyxia valve member in accordance with an embodiment of the present invention; 
           [0055]      FIG. 32  is a front view of a headgear clip according to the present invention; 
           [0056]      FIG. 33  is a perspective view thereof; 
           [0057]      FIG. 34  is a rear view thereof; 
           [0058]      FIGS. 34A and 34B  illustrate front and rear perspective views of a headgear clip according to another embodiment of the present invention; 
           [0059]      FIG. 35  illustrates a perspective view of headgear according to one embodiment of the present invention; 
           [0060]      FIG. 36  is a front perspective view of the headgear of  FIG. 35  in position on a human head; 
           [0061]      FIG. 37  is a rear perspective view of the headgear of  FIG. 35  on a human head; 
           [0062]      FIG. 38  illustrates yet another embodiment of headgear according to the present invention; 
           [0063]      FIG. 39  illustrates the headgear of  FIG. 38  from front perspective view on a human head; 
           [0064]      FIG. 40  illustrates the headgear of  FIG. 38  in rear perspective view on a human head; 
           [0065]      FIG. 41  illustrates a perspective view of headgear according to still another embodiment of the present invention; and 
           [0066]      FIG. 42  is a perspective view of the headgear of  FIG. 41  on a model patient&#39;s head. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0067]    Preferred embodiments of the present invention will be described in relation to the appended figures, in which like reference numerals refer to like parts. 
         [0068]      FIG. 1  shows a mask assembly  10  which includes a frame  12  in the form of a shell, and a cushion  14  that is provided, e.g., attached, to the frame  12 . A swivel elbow  16  is rotatably coupled or provided to the frame  12 . The swivel elbow  16  includes an inlet conduit  18  that receives pressurized breathable gas from a suitable source of pressurized air, as is known in the art. The swivel elbow  16  includes one or more apertures  20  which serve to continually wash out exhaled CO 2  gas from a breathing chamber formed by the frame  12  and the cushion  14 . The frame  12  includes at least a pair of lateral outriggers  22  which support connector clip receptacles  24  designed to receive connector clips (see, e.g.,  FIGS. 32-34 ) associated with headgear (see, e.g.,  FIGS. 35-40 ). The frame  12  includes a centrally located upper extension  38  including various structure intended to interlock with a headgear strap of headgear. 
         [0069]    Frame  12  also includes at least one port  26  that allows for the introduction of a pressure monitoring probe, or a separate gas such as oxygen (O 2 ) to be introduced (via a tube) into the interior of the breathing chamber. The port  26  may be suitably covered by a port cap  28  which is shown in the disconnected position in  FIG. 1 . As described and shown below, the port cap  28  may be formed as an integral part of the cushion  14 . 
         [0070]      FIG. 2  illustrates a patient&#39;s side or rear view of the mask assembly  10 . The face contacting portion of the cushion  14  preferably includes a double layer, spaced wall configuration as described in U.S. Pat. No. 6,513,526 assigned to ResMed Limited and incorporated herein by reference in its entirety. However, other cushion configurations such as single or triple layer cushion configurations could also be employed without departing from the spirit and scope of the present invention. In addition, the cushion can be made of silicone, foam, gel, etc., or combinations thereof. 
         [0071]      FIG. 2  also illustrates an aperture  30  which communicates the inlet conduit  18  of swivel elbow  16  to the breathing chamber. Surrounding aperture  30  is a generally circular support  32  formed as part of the frame  12 . The support  32  forms a surface for an anti-asphyxia valve membrane  34  (shown in detail in  FIGS. 29-31 ). As described in more detail below, the anti-asphyxia valve membrane  34  is positioned between the support  32  and the swivel elbow  16 . 
         [0072]      FIGS. 3 and 4  illustrate front and rear exploded views of the mask assembly  10  shown in  FIG. 1 , without the swivel elbow  16  or its associated anti-asphyxia valve membrane  34 . As shown in  FIG. 3 , the anti-asphyxia valve membrane  34  would be positioned adjacent circular support surface  36  of frame  12 . 
         [0073]    Frame  12  includes at least one and preferably a plurality of through holes  40  which are intended to align with complimentary through holes  42  provided on cushion  14 . The cushion  14  is intended to be sandwiched between frame  12  and a cushion clip  44 . The cushion clip  44  includes a corresponding number of fasteners or rods  46 , e.g., provided along a flanged perimeter portion  48  of the cushion clip  44 . The rods  46  are intended to align with and pass through the holes  42  and  40  of the cushion  14  and frame  12 , respectively. Tips of rods  46  may be snap-fitted, melted or ultrasonically deformed so as to lock with respect to apertures  40 , thereby effectively sandwiching the cushion  14  in place between the frame  12  and the cushion clip  44 . Rods  46  may include enlarged head portions that are tapered to allow penetration through holes  40 ,  42  for assembly purposes. However, enlarged heads help prevent disassembly of the frame, clip and cushion. Therefore, the cushion  14  may be permanently sandwiched in place, i.e., it is difficult to disassemble, which may be a benefit in a hospital or clinical environment. However, the cushion could be structured to allow for selective disassembly, if desired. The cushion  14  includes a lateral perimeter flange  50  which may also be sandwiched or clamped between the frame  12  and the cushion clip  44 .  FIG. 3  also shows that the flange  50  may provide a support surface for integral connection with port cap  28  via bridge  29 . In an alternative, the frame may be provided with the rods, and the cushion clip could be provided with holes. 
         [0074]      FIG. 4  best shows an inside surface  52  of the frame  12 . Provided adjacent inside surface  52  is an upstanding wall member  54  which preferably extends along the entire perimeter to define the opening of the frame  12 . The wall  54  provides support for the side walls of the cushion  14  as well as the interior side walls of cushion clip  44 .  FIGS. 5-7  illustrate further assembly views of the frame  12 , cushion  14  and swivel elbow  16 . 
         [0075]      FIGS. 8-12  illustrate further views of the frame  12  in isolation.  FIG. 8  shows that the frame  12  includes a notch  56  provided to facilitate passage of bridge  29  (see  FIGS. 3, 14 and 15 ) from the cushion side to the frame side. The frame  12  also includes a plurality of protrusions or castellations  60 , e.g.,  8  castellations, for the purposes of assisting with retention of anti-asphyxia valve membrane  34  in elbow assembly (see  FIGS. 22, 23 and 29 ). As shown in  FIG. 12 , the frame  12  includes a perimeter flange  64  which defines a groove  66  by which the swivel elbow  16  is secured to the frame  12 . 
         [0076]      FIG. 8  shows that the outrigger  22  includes legs  68 , each of which includes a first end attached or otherwise provided to main portion of the frame  12 , and a second end attached to or otherwise provided to the connector clip receptacle  24 . Preferably, the outriggers are formed as an integral piece with frame  12  and connector clip receptacle  24 . In addition, the outriggers  22 , e.g., legs  68 , may resiliently bend, and/or resiliently flex about an axis  72 , as indicated in  FIGS. 8 and 9 . Legs  68  can also be structured so as to pivot in a hinge-like manner. The provision of this type of movement allows for certain benefits, e.g., headgear strap self-tensioning and/or age/usage indication, more fully described below.  FIGS. 10-12  show top, bottom and side views of the frame  12 , respectively.  FIGS. 10 and 11  have bidirectional arrows which schematically indicate the bending, pivoting and/or flexing of legs  68  about axis  72 . 
         [0077]      FIG. 12A  illustrates a perspective view of an alternative embodiment of a frame  12 ′. The frame in  FIG. 12A  is very similar to the frame shown in  FIG. 8 , the only main difference being that frame  12 ′ includes 16 instead of 8 castellations  60 . The increased number of castellations helps to reduce leak between the elbows and anti-asphyxia valve membrane. However, the number of castellations may vary, and may, for example, include any number above or below 16. 
         [0078]    In another embodiment, one or both ends of legs  68  may include a portion  70  about which the leg(s) may pivot, bend and/or flex. This would allow the mask to assume various configurations, e.g., by moving the outrigger vertically up or down with respect to the main body of the frame, as schematically illustrated by arrows in  FIG. 9 . Preferably, the legs  68  should be parallel to one another to allow this adjustment, even though the legs are seen as non-parallel (i.e., trapezoidal) in  FIGS. 8 and 9 . 
         [0079]      FIGS. 13 through 15  illustrate various views of the cushion  14  in isolation, while  FIGS. 16 and 17  illustrate various views of the cushion clip  44  in isolation. 
         [0080]      FIG. 18  illustrates a partial cross-sectional and exploded view to highlight the connection between frame  12 , cushion  14 , and cushion clip  44 .  FIG. 19  is an assembled view of the components illustrated in  FIG. 18 , while  FIG. 20  is a perspective version of the exploded view shown in  FIG. 18 . As seen in  FIGS. 18-20 , frame  12  includes a bead-like member  13 , which helps to establish and ensure a reliable seal between frame  12  and cushion  14 .  FIG. 19  shows bead member  13  embedded within cushion  14 , although cushion  14  could also include a groove or aperture to receive bead member  13 . Bead member  13  can also be seen in  FIG. 4 . 
         [0081]      FIG. 21  illustrates an exploded view of a swivel elbow assembly  73 , including swivel elbow  16 , anti-asphyxia valve membrane  34  and swivel joint  76 . Swivel joint  76  includes first end  78  provided to inlet conduit  18  and second end  80  provided to an air delivery tube in communication with a source of pressurized breathable gas. 
         [0082]      FIG. 22  illustrates an assembled view of the components shown in  FIG. 21 , while  FIG. 23  shows a cross-sectional view of the assembled swivel elbow assembly. As shown in  FIG. 23 , the anti-asphyxia valve membrane  34  is preferably made of an elastomeric material. The swivel elbow  16  includes a generally cylindrical inner tube  82 . The cylindrical tube  82  may provide a baffle between incoming air delivered via swivel joint  76  and vented air, as indicated by the directional arrows in  FIG. 23 .  FIG. 23A  shows an enlarged detailed view of a portion of the assembly shown in  FIG. 23 , while  FIG. 23B  is a partial cross-sectional view illustrating the elbow as connected to frame with member  34  in position. 
         [0083]    The anti-asphyxia valve membrane  34  includes a main body  84  which seals and/or interlocks, e.g., via friction, with upstanding wall member  86  formed as part of swivel elbow  16 . Anti-asphyxia valve membrane  34  also includes an aperture  88  ( FIG. 21 ) which includes an inner shoulder  90  ( FIG. 23 ) for sealing against the outer surface of cylindrical tube  82  of swivel elbow  16 . The anti-asphyxia valve membrane  34  includes an outer shoulder  94  that prevents over-insertion of the membrane  34  within the swivel elbow  16  and allows for a snug fit with upstanding wall member  86  of swivel elbow  16 . 
         [0084]      FIG. 24  illustrates a perspective view of swivel elbow  16  as seen from the patient&#39;s side. Air is delivered via inlet conduit  18  into dome portion  98  of swivel elbow  16 . The swivel elbow includes a plurality of friction enhancing members  100  designed to ensure that the anti-asphyxia valve membrane  34  stays frictionally engaged with the swivel elbow  16 . 
         [0085]    The swivel elbow  16  also includes a plurality of slots or apertures  102  adjacent to which a plurality of tab members  104  are positioned, as seen in  FIGS. 24 and 25 . The tab members  104  are inclined ( FIG. 24 ) so that they slightly expand or cam-out upon engaging flange  64  as shown in  FIG. 12 , until overcoming the flange  64  and seating the tab members  104  within groove or undercut  66 , at which point the parts snap-fit to establish a connection. The provision of apertures  102  helps to weaken the swivel elbow  16  such that upon an attempt to disassemble the swivel elbow from the mask, the portion supporting the tab members or the tab members themselves deform and/or break away from the swivel elbow  16 , thereby rendering the mask unusable, in which case a new mask would be required for the patient. However, the selective weakening does not adversely impact the performance of the mask. Apertures  102  may also act as windows for breathing to atmosphere when the anti-asphyxia valve member is de-activated. 
         [0086]      FIGS. 26 through 28  illustrate various views of the swivel elbow  16  in isolation, while  FIGS. 29 through 31  illustrate various views of the anti-asphyxia valve member  34  in isolation. 
         [0087]      FIG. 28A  illustrates another embodiment of the invention, including a swivel elbow  16 ′ which is similar to elbow  16  shown in  FIG. 22 . One of the main differences is that elbow  16 ′ includes a single aperture  20 ′ provided for washout of exhaled CO 2  gas. Aperture  20 ′ may be fitted with a duck bill valve  23 , which is known in the art. 
         [0088]      FIGS. 28A-1 and 28A-2  illustrate an elbow according to a slight modification, in which the aperture  20 ″ is raised and a valve member  23 ′ is attached thereto. 
         [0089]    In the embodiments of  FIG. 28A  and  FIGS. 28A-1 and 28A-2 , members  23 ,  23 ′ constitute valve members. In another embodiment, members  23 ,  23 ′ could constitute plugs that selectively seal the aperture. When the plug is in place, the aperture is sealed and the elbow is non-vented. When the plug is removed, the aperture is exposed, thereby serving as an access port to receive a tube, e.g., naso-gastric in nature. 
         [0090]      FIGS. 28B and 28C  illustrate a swivel elbow  200  according to yet another embodiment of the present invention. Elbow  200  is intended to include an anti-asphyxia valve membrane (not shown) as described above. As shown in  FIG. 28B , elbow  200  includes a dome portion  202  and a cylindrical center tube member  204 . Upstanding wall  206  and tube member  204  are structured to support anti-asphyxia valve member. Dome is provided with a plurality of slots or apertures  208  and tab members  209 , each of which function as described herein. Provided to a peak portion of the dome  202  is a tube  210  having a first end  212  that extends through central aperture of anti-asphyxia valve membrane. Tube  210  includes a second end (not visible) which is integrally connected or provided to the peak of dome  202 . As such, dome will include only a single aperture, like that shown in  FIG. 28A . 
         [0091]    As shown in  FIG. 28C , tube member  204  includes an aperture  214  which is provided at a base of tube member  204 . Aperture  214  in this example is eye-shaped, although it could have any shape. 
         [0092]      FIGS. 28D-28H  illustrate an elbow  300  according to another embodiment of the present invention, which is similar to the embodiment of  FIGS. 28B and 28C . As shown in  FIGS. 28D and 28E , dome portion  302  includes a plurality of concentric, raised rings  303 . As shown in  FIGS. 28E-28H , center tube portion  304  extends just outside dome portion  302 , but ends before reaching the lower end of the elbow housing which helps with CO 2  gas washout. An inner tube  310  extends from the top of the dome portion  302  and past the end of the elbow housing. The top  311  of the inner tube  310  is profiled, as shown in  FIGS. 28E-28G . The opening  313  leading to atmosphere is of smaller cross-section than the central portion  315  of tube  310 . A transition  317  is formed between the opening  313  and central portion  315 . Transition, e.g., may take the form of a tapered conical section. Like the embodiment of  FIGS. 28B and 28C , central tube  302  includes an aperture  314  to allow the flow of gas from the air delivery conduit to the inside of tube  302 , which helps to lower impedance. 
         [0093]      FIGS. 31 -A to  31 -I illustrate a mask assembly  10  according to another embodiment of the present invention.  FIG. 31 -A is a front view of the mask assembly  10 , while  FIG. 31 -B is a side view of mask assembly  10 . The illustrated reference numbers denote components or parts that have been described in relation to one or more embodiments described above, e.g.,  FIG. 1 . 
         [0094]    Mask assembly  10  includes a swivel elbow  16 ′ that is more specifically discussed in relation to  FIGS. 31 -C- 31 -F. Elbow  16 ′ includes an inlet conduit  18  ( FIG. 31F ) having a hose end  18   a  with a plurality of resiliently deformable tabs  18   b  that are structured to allow selective attachment to and detachment from a swivel  76 . Each tab  18   b  includes a radially extending protrusion  18   c  that locks in place within an interior of groove  76   a  of swivel  76 .  FIG. 31 -E shows the assembled position. The elbow  16  is preferably made from a polyester, e.g., natural POCAN®, a Bayer product, although other materials are possible. The swivel  76  may be made of clear polycarbonate, although other materials are possible. This assembly allows for removal of the hose (not shown) without compromising the integrity of the frame. The internal geometry and functioning of the dome portion of elbow  16 ′ is similar to or the same as that described above or in relation to  FIGS. 28D-28H . Elbow  16 ′ may be used in conjunction with anti-asphyxia valve member  34 ′, as shown in  FIGS. 31 -G to  31 -I, whose function is similar to the member  34  described in relation to  FIGS. 29-31 . 
         [0095]      FIG. 32  illustrates a headgear clip  106  according to one embodiment of the present invention. The headgear clip  106  includes a first end  108  for engagement with headgear clip receptacle  24  shown in  FIGS. 1 and 2  and a second end  110  for engagement with a headgear strap of headgear assembly. The first end  108  includes first and second arms  112  which may be flexed toward one another in the plane of the paper so as to squeeze into receptacle  24 . The receptacle  24  includes an appropriate protrusion or catch  114  ( FIG. 1 ) in a locked position. To unlock the arms  112  from the catch  114 , each receptacle  24  includes a pair of opposed arm members  116  which may be pressed toward one another to thereby compress the arms  112  towards one another, thereby placing the headgear clip  106  in a position such that it can be removed from the outrigger  22  and the receptacle  24 . The geometry of clips  106  allows them to spring out of receptacles  24  when opposing arms  116  of receptacle are pressed. Each headgear clip  106  includes a central leg  118  including a groove  120  which is designed to receive a protrusion  122 , shown in  FIG. 2 .  FIG. 33  is a front perspective view of the headgear clip  106 , while  FIG. 34  is a rear view of the headgear clip  106 . Of course, different headgear clip and clip receptacles can be used instead. 
         [0096]      FIGS. 34A and 34B  illustrate another embodiment of a headgear clip  106 ′ which is similar to the clip  106  shown in  FIGS. 32-34 . Several changes have been made which may reduce manufacturing costs, facilitate manufacture, and/or enhance performance. 
         [0097]      FIG. 35  illustrates a first embodiment of headgear  124  according to the present invention. Headgear  124  may be manufactured by starting with a substantially flat piece of appropriate material, such as polyester loop material, Breathoprene®, leather, cloth, plastic, etc., and then cutting, scoring or weakening the headgear along predetermined cut lines  126  whereby the headgear  124  may be repositioned to approximate the shape of the patient&#39;s head. The headgear  124  may include side straps  128  and front strap  130 . Side straps  28  may be created with a single slit  126 . Also, in this example, main body  127  of strap has an appropriate amount of slits, e.g., 2-5 slits or more, to optimize coverage and stability of the headgear  124  or patient&#39;s head. Generally speaking, each of slits  126  expand in use to form a plurality of open spaces  126 ′, when the headgear is placed on the patient&#39;s head. 
         [0098]    The positioning of the headgear  124 , including the side straps  128  and front strap  130 , in relation to the mask assembly  10  and the patient&#39;s head is shown in  FIG. 36 .  FIG. 37  illustrates a rear perspective view of the patient&#39;s head with the headgear  124  provided thereto. This position cups the occiput of the head to thereby create stability. As can be seen from  FIGS. 36 and 37 , the headgear includes a plurality of fold lines  132  which are created due to repositioning of the headgear  124  from the position shown in  FIG. 35  to the position shown in  FIGS. 36 and 37 . These predetermined fold lines  132  are acceptable for use in a clinical or hospital environment. However, they do not adversely affect the performance of the headgear  124 . 
         [0099]      FIG. 38  illustrates a second embodiment of headgear  134  according to the present invention. Headgear  134  includes side straps  136  and front strap  138 . Again, the headgear  134  may be manufactured by providing a flat piece of material appropriate for use as headgear on a patient. Each side strap  136  is created by cutting the material along a predetermined cut line  140 . The headgear  134  may include a plurality of additional cut lines  142 , which creates a net-like configuration on the patient&#39;s head, as shown in  FIGS. 39 and 40 . Each cut line  142  forms an open area  142 ′, to effectively cup the patient&#39;s head. Open areas  142 ′ provide for ventilation of the patient&#39;s head. Open areas  142 ′ may be in the shape of a polygon, e.g., a triangle or a diamond. Of course, other headgear arrangement may also be used to support mask assembly on the patient&#39;s head. 
         [0100]      FIG. 41  illustrates headgear  400  according to another embodiment of the present invention. Headgear includes side straps  402 ,  404  and a top strap  406 , such that it can be used with the mask shown in  FIG. 1 . Headgear  400  includes cutouts  408  which help with ventilation and ensure that the headgear is fully retained. Cutouts  408  help headgear to conform to the patient&#39;s head. Headgear  400  includes a unidirectional stretch back piece  410 . Cutouts  408  may be separated by a divider  409  which may be detachably connected, e.g., via stitching and/or Velcro®, etc.  FIG. 42  shows the headgear in position on a model patient&#39;s head. 
       Disposable Characteristics 
       [0101]    The mask assembly  10  is intended to be used by a single patient for a limited life span and not reused on further patients. This removes the time and expense of cleaning and reassembling the product. In addition, it removes the difficulties found when components can be lost or assembled incorrectly. For safety reasons, and to avoid cross-infection, the product should have both the function and/or aesthetics of a disposable product in order to alert the user and discourage extended use or use on more than one patient. 
         [0102]    The mask assembly has been configured so as to satisfy needs of a clinical or hospital staff. This has been achieved while retaining mask performance desired by patients, which performance includes comfort, minimized leaks, etc., and therefore facilitates patient compliance with treatment. 
         [0103]    The mask appears to be disposable from the feeling that it is less durable than a reusable mask. The mask is purposely prone to distortion through handling because it is made from materials that have an expected service life, e.g., of about 7-14 days, and preferably no more than 7 days. In addition, the mask has the characteristic of displaying its “age”, e.g., via stress whitening (described in more detail below), and therefore provides an indication to users of the mask system&#39;s aging and approaching end-of-life. This aging characteristic is in contrast to prior art disposable masks that typically, without warning, fail in use, for example, when they are stressed while undergoing the procedures of disassembly, washing, assembly or fitting. 
         [0104]    The mask system provides a warning to users of approaching end-of-life. In addition, the aging characteristic is intended to serve the safety function of dissuading cross-patient use—the second intended user is disinclined to select or don a used mask. In this way, the aging characteristic facilitates the control of cross-infection and is therefore particularly useful in a clinical multi-patient environment. 
       Frame 
       [0105]    The frame may be formed by polypropylene, polyethylene, PETE, etc., and may be manufactured using a molding process, e.g., injection molding. Preferably, the frame is made of polypropylene with a thin walled section (approximately 0.25-1 mm, preferably about 0.5 mm) that gives it the characteristic of being more flexible than typical multi-use mask frames. Flexibility is desirable because it gives the feeling of being less durable. 
         [0106]    In the present embodiment, aging is achieved through the exhibition of “stress whitening.” Stress whitening occurs as a result of excessive or repeated deformation of polypropylene and other materials such as polyethylene or PETE. Such excessive and/or repeated deformation will eventually cause the frame material to turn white, ergo the term “stress whitening.” 
         [0107]    The present embodiment incorporates the characteristic to display stress whitening through an appropriate combination of design and/or components. For example, the wall thickness and stress loading can be designed so as to control stress whitening to occur in those portions of the mask which are most visible to the clinician. For example, the outriggers  22 , e.g., legs  68 , shown in  FIG. 8  may be designed such that they will deform when the headgear is fitted and as such they will exhibit stress whitening with use. As described above, the outriggers  22  include legs  68  which are intended to bend, flex or pivot about axis  72 , as shown in  FIGS. 8 and 9 . Repeated and/or excessive such movement can cause stress whitening. In other embodiments, stress whitening can be used to form a readable text message (e.g., “replace mask” or “discard”) which appears only after stress whitening has occurred. Of course, the mask could be designed such that stress whitening occurs in other locations. 
         [0108]    Stress whitening will give the visual indication that the mask system has been used. If the mask frame is configured so that the development of stress whitening (e.g., increase in intensity or area displaying stress whitening, or both) occurs as a result of repeated deformation during use, then the mask will also provide a visual indication of aging and approaching end-of-life. 
         [0109]    The development of stress whitening will also serve to provide a safety warning to users. By warning of imminent end-of-life, it thereby cautions against use of the mask where it can be expected to fail in use. 
         [0110]    Although the mask may exhibit some degree of stress whitening, stress whitening alone will not cause breakage, thereby causing a catastrophic failure. By contrast, the state of the prior art is that masks exhibit a tendency toward unexpected catastrophic failure, e.g., a component snapping, without warning. 
         [0111]    A complimentary but independent feature further enhances the frame&#39;s disposable characteristic. Some and preferably all components are configured to assemble with a one-way snap action. Once the mask frame/vent and anti-asphyxia valve and cushion components are assembled, they cannot be disassembled without breakage occurring. Further, disposable characteristics of a mask system are that the mask cannot effectively be cleaned as it cannot be disassembled which is a further indication that it is disposable, it is low cost, it has white headgear that is likely to show dirt, grime and wear, and/or it is appropriately labeled. 
         [0112]    The frame may include a headgear strap with a self-tensioning feature. This will facilitate a clinical party (i.e., non-patient) fitting of the mask without assistance of the patient. The flexible legs  68  that extend from the frame include attachment points for the lower two headgear straps. The flexibility allows for the legs to fold towards the back of the patient&#39;s head and thereby provide extra length to the headgear straps/flexible arms combination when fitting the mask system, thus allowing for the headgear to be located over the patient&#39;s head. Then, when the mask and headgear are in place, the legs spring forward, i.e., away from the patient&#39;s face, thereby placing some tension to the headgear mask assembly. This helps to avoid the need for cooperation of the patient. 
       Cushion 
       [0113]    The cushion  14  disclosed herein may adopt at least some of the same geometry as is available in the current Mirage® Full Face mask, which includes an upper membrane and an underlying profile. See U.S. Pat. No. 6,513,526 incorporated herein by reference in its entirety. 
         [0114]    The cushion  14  is attached to the frame  12  by sandwiching the cushion between the cushion clip  44  and the frame  12 . However, the cushion  14  may be attached to the frame  12  using mechanical (e.g., tongue and groove) and/or adhesive techniques. 
         [0115]    In an alternative assembly, the cushion can be molded directly to the frame, e.g., via over-molding, with the frame being made of polypropylene and the cushion being made of TPE. 
         [0000]    Anti-Asphyxia and/or Back Flow Reduction Valve 
         [0116]    The anti-asphyxia valve situated in the swivel elbow  16  functions as both an anti-asphyxia valve and a back flow reduction device. The valve is permanently assembled from three components—the elbow, the valve membrane  34  and the frame  12 . To assemble, the membrane  34  is an interference fit with the elbow  16  (see, e.g.,  FIGS. 23, 23A, 23B ) which is then a permanent snap fit to the frame  12 . The snap fit includes an undercut on the frame, e.g., groove  66  in  FIG. 12 , which connects with six tab members  104 , for example, on the elbow  16 . 
         [0117]    When the flow generator is switched off, or in the case of malfunction such as a power cut, the valve membrane  34  sits in the original or unextended position. The edge of the membrane forms a seal against the inner tube  82  of the elbow  16  and thus prevents flow from the mask reaching the inlet conduit  18  and consequently the flow generator. Thus, the valve prevents gas flow back to the flow generator which is particularly useful in circumstances where O 2  is ported into the mask. Any O 2  that is supplied to the mask cannot reach the flow generator, i.e., the valve acts as an O 2  divertor valve (ODV) and removes a potential fire hazard. In addition, see U.S. Patent Application Publication 2004/0094157 A1 assigned to ResMed Limited and incorporated by reference in its entirety. 
         [0118]    In the unpressurized state, air reaches the mask through the six slots  102  ( FIGS. 23B, 24 and 25 ) in the elbow  16  which connects with the circular inlet in the frame. Ambient air is channeled between the lower surface of valve member  34  and surface  36  ( FIG. 3 ) of frame  12 . Thus, the valve is also acting as an anti-asphyxia device. This embodiment has an advantage over ResMed&#39;s anti-asphyxia valve mentioned above in that it closes the flow to the inlet conduit  18 . This prevents air from be rebreathed from the inlet conduit  18 . 
         [0119]    When the flow generator is switched on and pressure is applied, the membrane  34  extends from its original position and forms a seal against the circular inlet (e.g., surface  36  in  FIG. 3 ) of the frame  12 . This pressurized air from the inlet conduit  18  can flow around the elbow inner tube  82  and directly through the circular inlet of the frame. The inner shoulder  90  may separate from the end of tube  82 , as shown in phantom in  FIG. 23A . In this position, the valve member is configured such that it may provide an audible noise, e.g., a whistle. This may provide comfort or a positive feedback signal to the patient/clinician that the device is assembled properly and/or that pressurized gas is being properly channeled. The audible signal, e.g., whistle, can be created by vibrations in a manner similar to that created when playing the reed of a musical instrument. Alternatively, a small gap may be designed to create the whistle effect. The device, e.g., the anti-asphyxia valve, may be arranged such that a noise is created if the system is not correctly assembled, to thereby provide a warning to the user or clinician. In general, the mask can be designed to include or not include noise, depending on preference. 
         [0120]    This design achieves a lower profile elbow, which is desirable both for aesthetic reasons and it improves the stability of the mask. Another factor to consider when designing the elbow is the entry impedance of the mask. It is desirable to minimize impedance in order to prevent pressure swings occurring during breaths. 
         [0121]    The lower profile elbow is achieved by a number of factors. Firstly, the elbow acts as the housing for the membrane and the valve is placed at the interface of the elbow in the frame. This reduces the number of components that are required (and associated manufacturing costs) as well as removing the bulk of a further interface. Secondly, the inlet conduit  18  is at an angle from the mask of greater than 90°, e.g., 100°-120°. Thirdly, the diameter of the inlet cavity has been increased. This increases the cross-sectional area presented to the inlet flow (and thus reduces the entry impedance) for a given elbow inlet angle. 
         [0122]    The valve is physically larger than the existing ResMed anti-asphyxia valve mentioned above to achieve a reduced impedance in the elbow compared to the currently available ODV. 
       Mask Vent 
       [0123]    The mask vent is incorporated in the elbow. Existing ResMed full face masks have their vents incorporated in the mask frame. 
         [0124]    Inadvertent leak is virtually zero due to the configuration of the vent and anti-asphyxia valve. This performance is achieved partly by configuring the anti-asphyxia valve to include a relatively soft part, e.g., membrane  34  made, e.g., of silicone, to seal between the frame and the swivel elbow. 
         [0125]    When a vented mask is adopted to be used with a ventilator there is a requirement to calibrate the vent. This process typically requires blocking of all the pathways to atmosphere so that the path to atmosphere occurring at the vent may be isolated and thereby characterized. 
         [0126]    By putting the vent in the elbow it is relatively easy to block the orifice joining the mask chamber and the elbow downstream of the vent so as to achieve the required isolation. This configuration avoids the difficult to perform blocking of the large path to atmosphere that occurs at the mask aperture, i.e., the mask chamber entry point which receives the patient&#39;s face. A plug may be used to block the orifice between the elbow and the mask chamber, but it may be also easily achieved in the clinical setting by placing a finger over the orifice. 
         [0127]    This is an advantage in a situation as compared to the prior art, which includes three sizes of frames with a vent in each frame, thereby requiring different tools for each frame/vent for calibration. This embodiment of the invention simply has a single elbow to calibrate for flow, independent of the mask frame size. 
         [0128]    The anti-asphyxia valve may be adopted for use in a multiple use full face mask as it is made from silicone where it will be robust, washable and capable of reassembly. The anti-asphyxia valve is then a common part, requiring less inventory and there will be no need to develop a new anti-asphyxia valve for a new face mask. 
       Frame Port and Port Cap 
       [0129]    The frame port cap is configured to meet clinical needs. The port cap is integrated into the cushion configuration, which allows the port cap to be formed at the time of cushion manufacture, thereby eliminating the need for separate manufacturing. This allows for a one molding operation to make the cushion and mask components. It also allows the port cap to pass through manufacturing and distribution chain as one component with the cushion. This simplifies handling and inventory logistics, and reduces manufacturing and warehousing costs. 
         [0130]    The location of the port cap in relation to the cushion are such that when the cushion is attached to the frame, the port cap is conveniently positioned to be attached to the frame port. 
         [0131]    These features are particularly welcome in the clinical setting where there is need to frequently attach and detach a port cap (e.g., when attaching or detaching lines to the frame port or for the measurement of treatment pressure, servo control of flow generator or delivering treatment gas such as O 2 ). With the port caps attached to the cushion it is always conveniently available to be attached to the frame port. 
         [0132]    In addition, the port cap has one or more large grip wings to facilitate convenient manipulation. A problem identified by the inventors is that the typical small port caps supplied with prior art masks are an annoyance to the regular clinical user. Grip wings may be supplied for a group of port caps or individually associated with each port cap. 
         [0133]    Preferably, the port and port cap are located at the bottom of the mask so as to avoid interference with other components of the mask assembly, as described in U.S. Pat. No. 6,439,230, assigned to ResMed Limited and incorporated herein by reference in its entirety. Of course, the port and port cap could be located in other convenient positions around the mask frame. In addition, multiple ports and caps could be provided to the same mask. 
       Headgear 
       [0134]    The headgear performs in a manner that contributes to the systems aging characteristic. This performance is achieved by use of material that gives a display of its accumulation of grime, i.e., soiling. The chosen material accumulates and displays its accumulation of grime, e.g., by visual and tactile signals. Preferably, the headgear when first brought into service is generally white or other a light shade of color. 
         [0135]    In addition to the objective visual signal, the aging characteristic achieved through the perception of soiling will provide a useful psychological signal. Potential users will not want to don a seriously soiled headgear while a clinical staff will be prompted to choose a fresh mask system for patients especially when fitting a patient new to the mask. 
         [0136]    Grime may be attributable to skin, sweat, oils, facial secretions, etc. The aging characteristic may be incorporated into the headgear and/or mask frame in such a way that the headgear or mask frame exhibits age due to exposure with such sources of grime. In other words, grime may provide a visual indication on the headgear frame to signal the clinician that it is time to replace the mask system. 
         [0137]    In another alternative, the aging characteristic can be provided with headgear which frays or otherwise decomposes after repeated use beyond the nominal set limits. 
         [0138]    The headgear strap configurations allow for more consistent location of straps under the patient&#39;s ear and thereby avoid the annoying contact of the strap with the lower portion of ear. 
         [0139]    Headgear may be configured from a die cut side piece, e.g., a laminated material which in its unassembled form is shaped to minimize waste and thus reduce costs/control. The waffle pattern, when expanded, will allow for expansion and correct placement on the head. This design achieves a three-point fitting configuration. A two-dimensional piece of material is used to achieve a three-point headgear which achieves the performance of a four or five-point headgear. This allows for placement of the top strap to follow a line which is low on the ears and resembles what is achievable with a four strap headgear, which allows for desirable distribution of forces but with the convenience of one top strap. 
       Headgear Clip 
       [0140]    The headgear clip mechanism includes a housing which incorporates release tabs and that is formed as part of the frame. A headgear clip is spring-fit into the receptacle on one side and acts as an attachment point for the headgear on the other side. The headgear attachment side has two slots. The first slot  111  ( FIGS. 32-34 ), closest to the mask, is a fully formed slot through which the headgear is threaded. The second slot  113 , closest to the headgear has large shaped tabs  115  formed on one side, between which a gap G exists. The gap G and the tapered shape of the tabs allows the headgear to be connected through the second slot by pulling down through the tabs. This assembly technique is much simpler than threading. 
         [0141]    Further benefits of the clip design are that the clip is very large which makes it easier for manipulation. The tabs  116  ( FIG. 1 ) to release the clip are operated from the top and bottom which facilitates the user configuration. Further, the tabs  116  form part of the frame, rather than part of the clip. Therefore, the tabs do not slide with the clip which makes single handed operation easier. 
         [0142]    The headgear clip may include a ladder lock and lead-in design. The headgear clip may serve as a quick release mechanism, i.e., the sprung release of the clip is a quick release mechanism. It has an exaggerated tactile finger tab to make it easier to find should there be a need for rapid response quick release. 
         [0143]    The headgear clip allows for quick manual assembly which serves both as a manufacturing aid and a benefit to customers as it allows for a presentation of a fully assembled product and benefits a clinical setting as it allows for quick reassembly when required. 
       Summary—General Effects of Preferred Embodiments 
       [0144]    Hospital and fully featured hospital use is characterized by several factors: single patient use, clinician requirements, and/or a desirability to discourage reuse. 
         [0145]    Ease of fitting may be achieved via a headgear spring/outrigger design. Ease of assembly prevents incorrect assembly and protects from interference and tampering. Disassembly is prevented between the cushion and frame since they are permanently connected. The elbow is snapped to the frame via a one-way snap, which cannot be disconnected without destroying or breaking the elbow and/or frame. The ports cap is formed as an integral portion of the cushion, thereby preventing its loss or detachment. 
         [0146]    The mask is designed to discourage reuse because there is no method of efficient cleaning that is possible as there is no access to the anti-asphyxia valve. Moreover, the mask displays evidence of use, e.g., via stress whitening and distortion under force. Stress whitening may be achieved by some combination of material, wall section dimensions, geometric form and/or use of a yielding flexible part. The materials may include polypropylene, polyethylene or PETE, and may be made by molding, such as injection molding or they may be vacuum formed. The stress whitening may be provided via the outriggers although the top support of the frame, the forehead support, port cap, etc. may also be used to exhibit stress whitening. Moreover, a living hinge could also be used to display evidence of use. 
         [0147]    Other alternatives to stress whitening include snapping via a one-way connection, to thereby prevent or inhibit reuse. Other possible indicators include exposure to air, O 2  or grime, exposure to condensation (moisture indicators), CO 2  detectors, etc. 
         [0148]    The mask frame is intended to look disposable and non-durable via one or more of the following criteria: material choice, color (headgear is white, frame could also be white). Headgear could be cardboard with a plastic interior, material thickness, simple construction and/or an exposed construction method. The mask feels disposable, e.g., the frame is flexible and will deform with predetermined and/or repeated application of force. 
         [0149]    The port and cap structure is advantageous since it is an integral component with the cushion, and cannot come apart from the assembly. Therefore, the port cap cannot be lost since it is attached to the cushion. This allows for lower manufacturing cost as the cushion and cap are one component rather than two. This also prevents cross-patient use. 
         [0150]    The port cap includes one or more large grip tabs, which are easier to operate, particularly for clinicians. The large grip tabs allow for easy location. The grip tabs are visible, and show whether they are on or off, and their operation is obvious to inexperienced users, thereby avoiding the error of cap being left off. 
         [0151]    The port cap is self-locating, meaning that the cap stays close to the port when removed, but requires little dexterity to place the port cap back onto the port, and does not require visual affirmation since affirmation can be provided via tactile means. 
         [0152]    The port cap is positioned at the bottom of the frame, which is near the nares, thereby providing an advantage for the supply of oxygen. The port cap is not susceptible to being disturbed by movement of the patient&#39;s head. The port cap allows an air inlet tube and swivel to rotate freely. The most common position of the air inlet tube is always away from the bottom, and the smaller tubes can be easily routed along the tube as commonly occurs. 
         [0153]    Alternative embodiments include a living hinge cap molded from the frame. This had the advantage of displaying evidence of use, e.g., stress whitening. 
         [0154]    In still further embodiments, a barbed head may be pulled through the frame or cushion wall, with the barbed head sealing against the frame. The port cap can be molded with a thin strap directly to either the cushion or the frame. The port cap may be sandwiched between the cushion and frame, which decreases the chances that the port cap can be lost. The port cap can be co-molded with the frame. The port cap can be molded integrally with the anti-asphyxia valve or the vent or any elastomeric component. The port cap can be purposely made to break off with use to display hospital use, to thereby convey the disposable nature of the mask. Alternatively, the port cap may develop a cut end with overuse. 
         [0155]    The above described self-tensioning feature facilitates fitting of the mask assembly to the patient. The self-tensioning spring provides elasticity when required, e.g., when initially taking the headgear over the head. This allows a larger degree of opening when fitting. In addition, it could be used with non-elastic headgear, and is particularly suitable for a third party/clinician fitting. 
         [0156]    The self-tensioning aspect provides a spring to give some tension when initially fitted before tightening the straps. This prevents the straps from simply flopping and prevents the tangling of straps. 
         [0157]    The self-tensioning aspect provides a visual indication that straps are not tight or tensioned. In a further embodiment, a tension indicator may be provided, which displays the amount of tension either by angle (this could be whilst on the patient) or with permanent deformation for clinical evaluation after patient use. 
         [0158]    The self-tensioning aspect keeps the headgear from tangling away from the patient, and may include broad attachment points, which maintain strap alignment and does not twist. 
         [0159]    The self-tensioning aspect also may display evidence of use, e.g., via stress whitening upon use. Evidence of use may also be demonstrated via use of various combinations of material, thickness and geometric form. The outriggers may also creep with use to a point at which it does not regain form after patient use. 
         [0160]    In alternative embodiments, the outriggers could be used on reusable masks. The headgear clips can be snapped into use under certain tension. This has an advantage of maintaining form and a larger degree of opening but does not act as a spring. This may give a strong indication of use by not maintaining form after first use, and encourage the product to be thrown away after single patient use. 
         [0161]    The outrigger assembly may include a living hinge, which may be advantageous from the aspect of keeping form in larger degree of opening but does not act as a spring. This would give a strong indication of use by not keeping form after first use, and encourage the product to be thrown away after single patient use. This would show use at the hinge point. 
         [0162]    In other alternatives, a self-tensioning spring could be attached to headgear rather than the frame. In addition, a tension indicator may display the amount of tension either by angle, whilst on the patient, or with permanent deformation for clinical evaluation after patient use. The hinge could be part of a cushion or a captive part of the cushion frame interface rather than part of the frame. The hinge could be incorporated into the designs of other existing disposable and reusable masks. 
         [0163]    Headgear according to the present embodiments include several features and/or advantages. For example, the headgear is manufactured using a strip design, which is the lowest volume for manufacture, meaning low wasted or inefficient use of materials. The design expands from a one-dimensional strip in manufacture to a three-dimensional cup in use. 
         [0164]    The process for making the headgear can be from a single stamp or slit within the perimeter of the strip. The headgear need not cover much of the head, is cool and is unobtrusive. The headgear achieves a simple yet stable design. Different colors can be provided on each side of the material for a visual clue as to the part which is facing towards and away from the patient, which allows for ease of assembly and non-tangling of the strap components. 
         [0165]    Alternative materials for the headgear include foam, silicone and/or breathable materials. The material can be elastic or non-elastic, of varying stiffnesses in different directions. Further, separate strips can be joined with varying stiffnesses. This will allow fine tuning of the elasticity of individual straps of the headgear. Various stiffnesses can also be achieved by sticking VELCRO® tapes over part of the headgear or by providing cross-stitching, etc. The headgear can also be manufactured by forming a number of individual components, laying them next to each other and then joining them via stitching, gluing, etc. 
         [0166]    While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention.