Patent Publication Number: US-2021170133-A1

Title: Mask system

Description:
This application is a continuation of U.S. application Ser. No. 15/364,605, filed Nov. 30, 2016, now allowed, which is a continuation of U.S. application Ser. No. 13/390,639, filed Feb. 15, 2012, now U.S. Pat. No. 9,539,403, which is the U.S. National Phase of International Application No. PCT/AU2009/001102, filed Aug. 26, 2009, each of which is incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a mask system used for treatment, e.g., of Sleep Disordered Breathing (SDB) with Continuous Positive Airway Pressure (CPAP) or Non-Invasive Positive Pressure Ventilation (NIPPV). 
     BACKGROUND OF THE INVENTION 
     Patient interfaces, such as a full-face or nasal mask systems, for use with positive airway pressure (PAP) devices in the treatment of sleep disordered breathing (SDB), typically include a soft face-contacting portion, such as a cushion, and a rigid or semi-rigid shell or frame. In use, the interface is held in a sealing position by headgear so as to enable a supply of air at positive pressure (e.g., 2-30 cm H 2 O) to be delivered to the patient&#39;s airways. 
     One factor in the efficacy of therapy and compliance of patients with therapy is the comfort and fit of the patient interface. 
     The present invention provides alternative arrangements of mask systems to enhance the efficacy of therapy and compliance of patients with therapy. 
     SUMMARY OF THE INVENTION 
     One aspect of the invention relates to a mask system including a frame defining a breathing chamber, a cushion provided to the frame and adapted to form a seal with the patient&#39;s face, and a shroud provided to the frame and adapted to attach headgear. The shroud includes a retaining mechanism structured to connect the shroud to the frame. The retaining mechanism includes both a taper lock arrangement and a retaining clip arrangement. 
     Another aspect of the invention relates to headgear for a mask system including a pair of upper straps adapted to connect to an upper portion of the mask system, a pair of lower straps adapted to connect to a lower portion of the mask system, and a cross bar to connect one of the upper straps to one of the lower straps on each side of the patient&#39;s head. The cross bar limits relative movement of the upper and lower straps relative one another so as to maintain the upper strap in a position away from the patient&#39;s field of vision and allow a force vector applied to upper strap to be directed towards the back of the patient&#39;s head in use. 
     Another aspect of the invention relates to a mask system including a frame defining a breathing chamber, a cushion provided to the frame and adapted to form a seal with the patient&#39;s face, and a shroud provided to the frame and adapted to attach headgear. The shroud includes upper headgear connectors adapted to attach upper headgear straps and lower headgear connectors adapted to attach lower headgear straps. Each lower headgear connector includes a clip receptacle adapted to removably interlock with a headgear clip associated with a respective lower headgear strap. Each clip receptacle is connected to the shroud via spaced-apart arm members that allow flexible movement of the clip receptacle in use. 
     Another aspect of the invention relates to a mask system including a frame defining a breathing chamber, a cushion provided to the frame and adapted to form a seal with the patient&#39;s face, and upper headgear connectors adapted to attach upper headgear straps and lower headgear connectors adapted to attach lower headgear straps. Each upper headgear connector includes an elongated arm and a slot at the free end of the arm adapted to receive a respective upper headgear strap and each lower headgear connector includes a clip receptacle adapted to removably interlock with a headgear clip associated with a respective lower headgear strap. The slot is oriented about 2-26° with respect to a vertical axis of the frame. 
     Another aspect of the invention relates to a mask system including a frame defining a breathing chamber, a cushion provided to the frame and adapted to form a seal with the patient&#39;s face, and a shroud provided to the frame and adapted to attach headgear. The shroud includes upper headgear connectors adapted to attach upper headgear straps and lower headgear connectors adapted to attach lower headgear straps. Each lower headgear connector includes a clip receptacle adapted to removably interlock with a headgear clip associated with a respective lower headgear strap. Each clip receptacle is oriented about 2-12° with respect to a vertical axis of the frame. 
     Other aspects, features, and advantages of this invention will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, which are a part of this disclosure and which illustrate, by way of example, principles of this invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings facilitate an understanding of the various embodiments of this invention. In such drawings: 
         FIG. 1-1  is a perspective view of a mask system according to an embodiment of the present invention; 
         FIG. 1-2  is a side view of the mask system of  FIG. 1-1 ; 
         FIG. 2-1  is a perspective view of the mask system of  FIG. 1-1  without headgear; 
         FIG. 2-2  is a side view of the mask system of  FIG. 2-1 ; 
         FIG. 3-1  is a side view of the frame and upper headgear connector of the mask system of  FIG. 1-1 ; 
         FIG. 3-2  is a rear view of the frame and upper headgear connector of  FIG. 3-1 ; 
         FIG. 4-1  is a perspective view of the frame of the mask system of  FIG. 1-1 ; 
         FIG. 4-2  is a front view of the frame of  FIG. 4-1 ; 
         FIG. 4-3  is a side view of the frame of  FIG. 4-1 ; 
         FIG. 4-4  is a top view of the frame of  FIG. 4-1 ; 
         FIG. 5-1  is a side view showing different sizes of the frame of  FIG. 4-1 , in overlapping relation; 
         FIG. 5-2  is a front view showing different sizes of the frame of  FIG. 4-1 , in overlapping relation; 
         FIGS. 6-1 to 6-6  are various views of an upper headgear connector according to an embodiment of the present invention; 
         FIGS. 7-1 to 7-5  are various views of an upper headgear connector according to an embodiment of the present invention; 
         FIG. 8-1  is a top view showing different sizes of the upper headgear connector of  FIG. 6-1 , in overlapping relation; 
         FIG. 8-2  is a top view showing different sizes of the upper headgear connector of  FIG. 6-1 , in spaced relation; 
         FIG. 8-3  is a side view showing different sizes of the upper headgear connector of  FIG. 6-1 , in overlapping relation; 
         FIG. 8-4  is a side view showing different sizes of the upper headgear connector of  FIG. 6-1 , in spaced relation; 
         FIG. 8-5  is a rear view showing different sizes of the upper headgear connector of  FIG. 6-1 , in overlapping relation; 
         FIG. 8-6  is a rear view showing different sizes of the upper headgear connector of  FIG. 6-1 , in spaced relation; 
         FIG. 8-7  is a front view showing different sizes of the upper headgear connector of  FIG. 6-1 , in overlapping relation; 
         FIG. 8-8  is a front view showing different sizes of the upper headgear connector of  FIG. 6-1 , in spaced relation; 
         FIGS. 9-1 and 9-2  show exemplary dimensions for a large size mask system of  FIG. 1-1 ; 
         FIGS. 9-3 and 9-4  show exemplary dimensions for a medium size mask system of  FIG. 1-1 ; 
         FIGS. 9-5 and 9-6  show exemplary dimensions for a small size mask system of  FIG. 1-1 ; 
         FIG. 10-1  is an enlarged front perspective view showing the frame and upper headgear connector of the mask system of  FIG. 1-1 ; 
         FIG. 10-2  is an enlarged front perspective view showing the frame of the mask system of  FIG. 1-1 ; 
         FIG. 10-3  is an enlarged rear perspective view showing the upper headgear connector of the mask system of  FIG. 1-1 ; 
         FIG. 10-4  is an enlarged rear perspective view showing the frame and upper headgear connector of the mask system of  FIG. 1-1 ; 
         FIG. 10-5  is a cross-sectional view showing the frame and upper headgear connector of the mask system of  FIG. 1-1 ; 
         FIG. 10-6  is a cross-sectional view showing the frame and upper headgear connector of the mask system of  FIG. 1-1 ; 
         FIG. 10-7  is a cross-sectional view showing the frame, cushion, and upper headgear connector of the mask system of  FIG. 1-1 ; 
         FIG. 11-1  is a front perspective view of a mask system according to another embodiment of the present invention; 
         FIG. 11-2  is a side perspective view of the mask system of  FIG. 11-1 ; 
         FIGS. 12-1 to 12-4  are various views of a mask system according to another embodiment of the present invention; 
         FIGS. 13-1 to 13-4  are various views of the frame and shroud of the mask system of  FIG. 12-1 ; 
         FIGS. 14-1 to 14-4  are various views of the shroud of the mask system of  FIG. 12-1 ; 
         FIG. 15-1  is a top view of the frame and shroud of the mask system of  FIG. 12-1  showing flexibility of the lower headgear connectors; 
         FIGS. 15-2 and 15-3  are bottom and front views of the mask system of  FIG. 12-1  showing flexibility of the lower headgear connectors; 
         FIGS. 15-4 and 15-5  are front and side views of the mask system of  FIG. 12-1  showing flexibility of the lower headgear connectors in use; 
         FIG. 16-1  is a cross-sectional view of the frame and shroud of the mask system of  FIG. 12-1 ; and 
         FIG. 16-2  is an enlarged top view of the frame and shroud of the mask system of  FIG. 12-1 . 
     
    
    
     DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS 
     The following description is provided in relation to several embodiments which may share common characteristics and features. It is to be understood that one or more features of any one embodiment may be combinable with one or more features of the other embodiments. In addition, any single feature or combination of features in any of the embodiments may constitute additional embodiments. 
     In this specification, the word “comprising” is to be understood in its “open” sense, that is, in the sense of “including”, and thus not limited to its “closed” sense, that is the sense of “consisting only of”. A corresponding meaning is to be attributed to the corresponding words “comprise”, “comprised” and “comprises” where they appear. 
     The term “air” will be taken to include breathable gases, for example air with supplemental oxygen. 
     The term “shroud” will be taken to include components that partially or fully cover a second component within the illustrated embodiments. In an embodiment, the shroud may include the component that partially covers or is mounted on the frame components of the illustrated embodiments. 
     1. Mask System 
     As described in greater detail below, the mask system includes a frame, a cushion provided to the frame and adapted to form a seal with the patient&#39;s face, a shroud provided to the frame and adapted to attach headgear, and an elbow provided to the frame and adapted to be connected to an air delivery tube that delivers breathable gas to the patient. Headgear may be removably attached to the top and bottom of the frame either directly or via the shroud, which provides headgear connection points for headgear positioned and arranged to stably maintain the mask system in position on the patient&#39;s face. The mask system is intended for use in positive pressure therapy for users with Obstructive Sleep Apnea (OSA) or another respiratory disorder. 
     While each embodiment below is described as including a full-face or oro-nasal interface type, each embodiment may be adapted for use with other suitable interface types. That is, the interface type is merely exemplary, and each embodiment may be adapted to include other interface types, e.g., nasal interface, nasal mask, nozzles, nasal prongs, etc. 
     Also, each illustrated embodiment includes features that may be used with the embodiments and/or components described in PCT Application No. PCT/AU2009/000241, filed Feb. 27, 2009, as would be apparent to those of ordinary skill in the art. The above noted application is incorporated herein by reference in its entirety. However, it should be appreciated that any single feature or combination of features in any of the embodiments may be applied to other suitable mask arrangements. 
     1.1 Frame 
     As shown in  FIGS. 1-1 to 4-4 , the frame  20  of the mask system  10  is structured to maintain the cushion  40 , shroud  50 , and elbow  60  in an operative position with respect to the patient&#39;s face. 
     The frame  20  defines a breathing chamber or cavity adapted to receive the patient&#39;s nose and mouth and provide air communication to the patient. One or lower portion of the frame includes an opening  22  adapted to receive or otherwise communicate with the elbow  60  (e.g., swivel elbow) and another or upper portion of the frame includes an opening  81  to support a vent arrangement  80  (e.g., see  FIGS. 1-1 to 2-2 ) for gas washout. In an embodiment, the vent arrangement  80  may be integrally formed in one piece with the frame. Also, the upper portion of the frame includes an interfacing structure adapted to interface or otherwise removably connect to the shroud  50 , as described in greater detail below. 
     In an alternative embodiment, the lower portion of the frame may also include an interfacing structure adapted to interface or otherwise removably connect to the shroud (e.g., see  FIG. 16-1  described below). 
     1.1.1 Lower Headgear Connectors 
     In the embodiment of  FIGS. 1-1 to 4-4 , the bottom or lower portion of the frame  20  includes lower headgear connectors  30  adapted to attach headgear. The lower headgear connectors  30  may be integrally formed in one-piece with the frame. Each lower headgear connector  30  includes a clip receptacle  32  adapted to be removably interlocked with a headgear clip  34  associated with a respective headgear strap. The clips allow for easier positioning or donning/removal of the mask system. 
     In an embodiment, the headgear clip receptacle and clip may be similar to that on ResMed&#39;s Mirage Quattro™ mask or ResMed&#39;s Mirage Liberty™ mask. Exemplary clip arrangements are disclosed in U.S. Patent Publication Nos. 2007/0157353 and 2006/0283461, each of which is incorporated herein by reference in its entirety. 
     The frame may be provided in different sizes, e.g., small, medium, and large. As shown in  FIGS. 5-1 and 5-2 , the position of the clip receptacles  32  may change or vary between sizes, e.g., shift vertically. The positioning of the receptacles may be selected to enhance sealing, e.g., by changing the application point for headgear tension. 
     1.1.2 Vent Arrangement 
     As best shown in  FIGS. 1-1 to 2-2, 10-1, 10-2, and 10-4 , the vent arrangement  80  is in the form of a diffused vent cap that may be integrally formed in one-piece with the frame  20 . The vent cap includes a base wall  82 , a dome  84  that extends upwardly from the base wall  82  above the horizontal surface of the base wall  82 , and multiple vent holes  86  arranged on an annular side wall of the dome  84  to provide diffuse airflow that is directed away from the patient&#39;s face as well as the bed partner (e.g., see  FIGS. 10-1 and 10-4 ). The angle of the diffused airflow can be tuned by altering the dimensions of the vent cap. The diffused airflow provides venting over a larger area to minimize jetting and may also reduce noise. 
     In the illustrated embodiment, as shown in  FIG. 1-2 , the vent cap  80  directs exhaust flow up and out from the mask, e.g., angle α is about 0-30°, e.g., 15°, 20°. In an embodiment, angle α is about 20° to ensure that air is not directed onto the patient&#39;s face. 
     In the illustrated embodiment, the vent holes  86  are arranged radially along the annular side wall of the dome  84  to radially divide the exhaust flow in 360°. In an embodiment, the vent cap may include 10-40 vent holes, e.g., 25 vent holes. 
     In the illustrated embodiment, the diameter of the vent cap (when viewed from above) is about 10-25 mm, e.g., 18 mm. 
     Further details and/or alternative arrangements of such vent arrangement are disclosed in U.S. Patent Application Publication No. US 2009/0050156 A1, which is incorporated herein by reference in its entirety. 
     However, it should be appreciated that the vent arrangement may include other suitable arrangements, e.g., different number of holes, hole arrangement, positioning on frame, etc. Also, it should be appreciated that the vent arrangement may be in the form of a vent insert (e.g., elastomeric vent insert) that is adapted to be removably supported within an outlet opening in the frame. In addition, it should be appreciated that the vent arrangement may be provided to the elbow. 
     1.2 Shroud 
     The shroud is connected to the frame and is structured to attach headgear to the mask system. The shroud may be constructed (e.g., injection molded) of resilient material including, but not limited to, plastics (such as Nylon or Nylon 12) or non-plastics. The shroud may be constructed of any suitable material which could also include: textiles, polycarbonate, polypropylene, thermoplastic elastomer (TPE), or Pocan®, etc. 
     1.2.1 Upper Headgear Connector or Rigidizer 
     In the embodiment of  FIGS. 1-1 to 3-2 , the shroud  50  is in the form of a snap-on upper headgear connector or upper headgear rigidizer that is connected to the top of the frame  20  and is structured to attach upper headgear straps to the frame. This shroud is used in conjunction with the frame  20  including lower headgear connectors  30  adapted to attach lower headgear straps to the frame. 
     As best shown in  FIGS. 6-1 to 6-6 , the upper headgear rigidizer  50  includes a frame connecting portion  52  adapted to connect the upper headgear rigidizer to the frame. The frame connecting portion  52  is adapted to connect to the frame at a position proximal to the nasal bridge region or nose of the patient. The frame connecting portion  52  includes a contoured or general “U” shape to accommodate the vent arrangement  80  provided to the frame  20 . Further details of connection are described below. 
     The upper headgear rigidizer  50  also includes arms  54  that extend from respective sides of the frame connecting portion  52 . Each arm  54  includes a slot or receiving hole  55  at the free end thereof adapted to receive a respective headgear strap. In use, the arms  54  extend around the face of the patient in a generally concave angle below the eyes of the patient so as to avoid the patient&#39;s field of view, i.e., direct headgear away from the patient&#39;s eyes. The hole  55  may alternately be replaced with a series or plurality of holes to provide for increased adjustability. 
       FIGS. 11-1 and 11-2  illustrate an upper headgear rigidizer  50  according to an alternative embodiment. In this embodiment, the arm  54  is abbreviated or relatively short. 
     Preferably, the rigidizers may function to modify the force vectors acting on the mask system. In these embodiments, the rigidizer provides an attachment point for the headgear at the upper most extreme of the mask system, while simultaneously providing a means to avoid the headgear straps from entering or impeding the patient&#39;s field of vision. The rigid connection between the rigidizer and the top of the mask system allows adjustments to the headgear to be transmitted to the top of mask system via the rigidizer. Additionally, the rigidizer may act as a type of lever to provide a mechanical advantage to any turning force applied to them. 
     1.2.2 Different Sizes 
     The upper headgear rigidizer  50  may be provided in different sizes, e.g., small, medium, and large, e.g., for use with different size frames as described above or a one size fits all type of frame. For example, as shown in  FIGS. 8-1 to 8-8 , the size, angle, and/or orientation of the arms may vary or change between sizes. 
     As shown in  FIGS. 9-1 and 9-2 , a large size upper headgear rigidizer may include the following dimensions: d 1  of about 120-180 mm (e.g., 153 mm), d 2  of about 116-136 mm (e.g., 126 mm), d 3  of about 107-127 mm (e.g., 117 mm), d 4  of about 68-88 mm (e.g., 78 mm), d 5  of about 88-108° (e.g., 98°), d 6  of about 28-48° (e.g., 38°), d 7  of about 98-118 mm (e.g., 108 mm), d 8  of about 59-79 mm (e.g., 69 mm), d 9  of about 39-59 mm (e.g., 49 mm), d 10  of about 35-55 mm (e.g., 45 mm), and d 11  of about 6-26° (e.g., 16°). 
     As shown in  FIGS. 9-3 and 9-4 , a medium size upper headgear rigidizer may include the following dimensions: d 1  of about 120-163 mm (e.g., 148 mm), d 2  of about 113-133 mm (e.g., 123 mm), d 4  of about 66-86 mm (e.g., 76 mm), d 5  of about 92-112° (e.g., 102°), d 6  of about 34-54° (e.g., 44°), d 7  of about 88-108 mm (e.g., 98 mm), d 8  of about 57-77 mm (e.g., 67 mm), d 9  of about 33-53 mm (e.g., 43 mm), d 10  of about 33-53 mm (e.g., 43 mm), and d 11  of about 2-22° (e.g., 12°). 
     As shown in  FIGS. 9-5 and 9-6 , a small size upper headgear rigidizer may include the following dimensions: d 1  of about 115-160 mm (e.g., 126 mm), d 2  of about 94-114 mm (e.g., 104 mm), d 4  of about 68-88 mm (e.g., 78 mm), d 5  of about 56-76° (e.g., 66°), d 6  of about 34-54° (e.g., 44°), d 7  of about 86-106 mm (e.g., 96 mm), d 8  of about 49-69 mm (e.g., 59 mm), d 9  of about 29-49 mm (e.g., 39 mm), d 10  of about 29-49 mm (e.g., 39 mm), and d 11  of about 2-22° (e.g., 12°). 
     It is noted that dimension d 1  for the different sizes is a width of the arms and relates to fit across face widths. It is noted that dimension d 7  for the different sizes relates to fit and clearance between the patient&#39;s eyes/ears. It is noted that dimension d 11  for the different sizes relates to the headgear force vector (indicated as a dashed arrow in  FIGS. 9-2, 9-4 , and  9 - 6 ). In an embodiment, the arms may be contoured or flexed such that the arms lay substantially flat or horizontal (when viewed from the top such as  FIG. 9-1 ), e.g., to accommodate largest face range. 
     1.2.3 Upper and Lower Headgear Connectors 
       FIGS. 12-1 to 16-2  illustrate a mask system  210  including a shroud  250  with both upper and lower headgear connectors  251 ,  231 . The shroud  250  is used in conjunction with the frame  220  including no integral headgear connectors. 
     As illustrated, the top end of the shroud  250  is adapted to be positioned proximal to the nasal bridge region or nose of the patient and the bottom end is adapted to be positioned proximal to the mouth or chin of the patient (e.g., see  FIGS. 15-4 and 15-5 ). The top end of the shroud includes an opening or vent receiving hole  258  to accommodate the vent arrangement  280  provided to the frame, and the bottom end includes an opening or elbow hole  259  to accommodate the elbow  260 . 
     The upper headgear connectors  251  extend from each side of the top end, and the lower headgear connectors  231  extend from each side of the lower end. The headgear connectors  251 ,  231  may be integrally molded or otherwise attached to the shroud. 
     Each upper headgear connector  251  includes a curved arm  254  and a slot or receiving hole  255  as described above. The hole  255  may alternately be replaced with a series or plurality of holes to provide for increased adjustability. 
     Each lower headgear connector  231  includes a clip receptacle  232  adapted to be removably interlocked with a headgear clip  234  associated with a respective headgear strap. Each clip receptacle  232  is connected to the shroud via spaced-apart arm members  233 , e.g., “wishbone” connection. As shown in  FIGS. 15-1 to 15-3 , the shroud  250  is molded such that the arm members  233  support the clip receptacles  232  in a raised or spaced position with respect to the frame  220  when no headgear tension is applied. Upon the application of headgear tension, the arm members  233  allow the clip receptacles  232  to flex towards and into contact with the frame  220  in use, e.g., to position the force vectors.  FIGS. 15-4 and 15-5  show the mask system  210  in position on the patient&#39;s head in use. 
       FIGS. 15-2 and 15-3  show exemplary angles/force vectors provided by the clip receptacles when the mask system is worn by the patient. It is noted that such angles/force vectors may be consistent across all sizes of the shroud, e.g., small, medium, and large. In the embodiment shown in  FIGS. 15-2 and 15-3 , a 1  may be about 40-50°, e.g., 45°, and a 2  may be about 2-12°, e.g., 7°. However, other dimensions are possible. 
     Also, it is noted that the upper headgear connector  251  of the shroud  250  may include similar dimensions as described above with respect to the embodiment of the upper headgear connector  50  of  FIGS. 9-1 to 9-6 , for small, medium, and large sizes. 
     1.2.4 Arm Padding 
     In an embodiment, the arms  54 ,  254  may be used to stabilize the mask system by contacting the patient&#39;s face at the cheeks. As shown in  FIGS. 1-1 to 2-2 and 12-1 to 12-4 , the arms  54 ,  254  of the upper connectors  50 ,  251  may be enveloped in a soft fabric sleeve or padded material  90  to act as padding against the cheeks of the patient, e.g., for patient facial comfort. The soft fabric sleeve  90  may be in the configuration of an elastic tube or sock covering a portion of the arms. 
     Also, the arms  54 ,  254  may be structured to retain the sleeve  90  thereon, e.g., prevent relative movement between the sleeve and arm. For example, as shown in  FIGS. 14-1 to 14-4 , the distal end of the arm (providing the slot) includes an enlarged head which provides a shoulder  257 ( 1 ) for retaining an end of the sleeve. In addition, the proximal end of the arm includes a widened portion which provides a shoulder  257 ( 2 ) for retaining the other end of the sleeve. 
     1.3 Headgear 
     Headgear may be removably attached to the headgear connectors to maintain the mask system in a desired position on the patient&#39;s face. 
     As shown in  FIGS. 1-1 and 1-2 , the headgear  70  includes a pair of upper straps  72  and a pair of lower straps  74  with the upper straps  72  removably attached to respective upper headgear connectors  50  and the lower straps  74  removably attached to respective lower headgear connectors  30 . The free end of each strap  72 ,  74  may include a Velcro® tab structured to engage the remainder of the strap to secure the strap in place. Such Velcro® attachment also allows adjustment of the length of the straps. However, the upper and lower headgear straps may be secured to the headgear connectors in any other suitable manners, e.g., adjustable ladder-lock arrangement, etc. 
     The upper straps  72  split at the crown of the patient&#39;s head to a top strap  75  adapted to pass over the top of the patient&#39;s head in use and a rear strap  76  adapted to pass behind the patient&#39;s head in use. Such arrangement may help to realign the upper headgear vectors to prevent the mask system from sliding up the patient&#39;s face in use. 
       FIGS. 15-4 and 15-5  illustrate similar headgear  70  attached to the headgear connectors  251 ,  231  of the shroud  250  of mask system  210 . 
       FIGS. 11-1 and 11-2  illustrate headgear according to an alternative embodiment. In this embodiment, a cross bar or connecting member  78  is provided to connect the upper and lower straps  72 ,  74 . As illustrated, the connecting member  78  extends generally vertically in front the patient&#39;s ear and close to the patient&#39;s cheek in use. The connecting member  78  assists with headgear vectoring. For example, the upper strap  72  runs horizontally across the patient&#39;s cheeks to avoid obstructing the patient&#39;s eyes and to pull the mask directly onto the patient&#39;s face to get the mask to seal, and then the top strap turns upwards over the patient&#39;s ears to secure the mask on the patient&#39;s head without contacting the ears (which can be uncomfortable) and also pulls the mask upwards to prevent it from slipping down. The connecting member  78  limits relative movement of the upper and lower straps relative one another to maintain the positioning and alignment of the upper and lower straps  72 ,  74  to enhance alignment of the vectors for sealing. 
     Preferably, the cross bar  78  joins the upper and lower straps and maintains the upper strap in a position away from the field of vision of the patient. Additionally, the cross bar may alter the force vectors applied by the headgear to the mask system, by allowing the force vectors to applied to both the upper and lower straps in the same general direction towards the back of the patients head, when in use. Preferably, the cross bar may be adapted as such to allow the upper and lower strap to presented in a generally parallel alignment with each other. It is noted that the cross bar may not extend generally vertically, i.e., other configurations are possible. 
     Additionally, the cross bar may be elastic and flexible and be constructed of a similar material as to the other portions of the headgear and straps. 
     In alternative embodiments, the straps of the headgear may be able to connect directly to the frame through integrally molded loops, holes or apertures. Also, the headgear may include a strap constructed of multiple interlocking hook and loop (e.g., Velcro™) arrangements. The corresponding hook and loop pieces may be joined and aligned in a strap configuration, which may allow the user or patient to quickly and easily release the strap by separation of the hook and loop interlocking layers. This may serve as a quick release mechanism. 
     1.4 Cushion 
     The cushion  40  is structured to interface with the frame and form a seal with the patient&#39;s nose and mouth in use. In the illustrated embodiment, the cushion is a full-face cushion adapted to engage the patient&#39;s face generally along nasal bridge, cheek, and lower lip/chin regions of the patient&#39;s face. However, other cushion interfaces are possible, e.g., nasal. 
     The cushion may include a two or more wall configuration wherein the cushion comprises membrane and one or more undercushions or support walls underneath the membrane. 
     1.5 Elbow 
     As shown in  FIG. 1-1  for example, the elbow  60  includes a first end portion providing an interfacing structure structured to interface or otherwise attach to the frame  20  and a second end portion including a swivel joint  62  is adapted to be connected to an air delivery tube. 
     1.5.1 AAV 
     The elbow is structured to support an anti-asphyxia valve (AAV), which includes a flap portion adapted to selectively close a port  64  on the elbow (depending on the presence of pressurized gas). 
     Alternative embodiments of the AAV are disclosed in PCT Application No. PCT/AU2006/000031, which is incorporated herein by reference in its entirety. 
     1.6 Shroud to Frame Connection 
     The shroud is mounted on the outer surface of the frame, e.g., preferably with a tight, conforming fit on the frame. 
     1.6.1 Retaining Mechanism 
     In the illustrated embodiment of  FIGS. 1-1 to 3-2 , the upper headgear rigidizer  50  is connected to the frame  20  by a retaining mechanism or interfacing structure located on the top end of the frame. 
     The retaining mechanism includes a taper lock arrangement and a retaining clip arrangement. In addition, an alignment feature is provided to facilitate alignment and connection of the upper headgear rigidizer to the frame. 
     As best shown in  FIGS. 4-1 to 4-4 and 10-2 , opposing sides of the top end of the frame include a platform  24  which provides a first female slot  25 ( 1 ). In addition, the space between the platform  24  and the outer surface of the frame  20  defines a second female slot  25 ( 2 ). As best shown in  FIGS. 6-1 to 6-3 and 10-3 , opposing sides of the frame connecting portion  52  of the upper headgear rigidizer  50  include a tang protrusion  53  on the underside thereof. The tang protrusion  53  includes a first tang  53 ( 1 ) and a second tang  53 ( 2 ) that extends generally transverse to the first tang. Each tang may taper along its length, i.e., thinner towards its free end. 
     As shown in  FIGS. 10-5 and 10-6 , the tangs  53 ( 1 ),  53 ( 2 ) of each tang protrusion  53  are structured to engage with respective slots  25 ( 2 ),  25 ( 1 ). As best shown in  FIG. 10-5 , the tang  53 ( 1 ) may include lead-ins or guides  56  that curve along their length so as to guide the tang into the slot and aid assembly. 
     As best shown in  FIGS. 6-1 to 6-3 and 10-3 , the upper portion of the frame connecting portion  52  includes a pair of spaced apart clip arms  65  with a locking tab  65 ( 1 ) provided to each clip arm. In use, each clip arm is adapted to clip onto or overhang the edge of the frame  20 , e.g., with a snap-fit, as shown in  FIGS. 3-2, 10-4, and 10-7 . 
     Specifically, the clip arms are adapted to engage the frame as the taper locks are progressively engaged. In an embodiment, the clip arms may provide an audible click once clipped onto the frame to indicate or confirm correct assembly. 
     In the illustrated embodiment, as best shown in  FIGS. 10-1 to 10-3 , the alignment feature includes a tab  26  provided to the frame and a slot  66  provided to the upper headgear rigidizer  50  and adapted to receive the tab  26  therein when the upper headgear rigidizer is engaged with the frame. However, other alignment features are possible, e.g., one or more alignment markings. 
       FIGS. 7-1 to 7-5  show an upper headgear rigidizer  50  according to an alternative embodiment. In this embodiment, the retaining mechanism only includes the retaining clip arrangement, i.e., no taper lock. 
     In the embodiment of  FIG. 12-1 , the top end of the shroud  250  may be connected to the frame using a taper lock arrangement and/or a retaining clip arrangement as described above. 
     1.6.2 Lower Retaining Mechanism 
     The lower end of the shroud  250  and frame  220  includes a lower retaining mechanism to connect the lower end of the shroud to the frame. In the illustrated embodiment, as shown in  FIG. 16-1 , the lower end of the shroud  250  includes a lug protrusion  268  adapted to mate into a corresponding recess or undercut  228  provided to the frame  220  so as to retain the shroud  250  in position. As illustrated, the lug protrusion  268  is in the form of a short bump that protrudes outwardly along a length of the shroud edge. For example, the protrusion  268  may extend along edges “x” of the shroud  250 , and/or the protrusion  268  may extend along edges “y” of the shroud  250  as shown in  FIG. 12-2 . 
     As shown in  FIGS. 16-1 and 16-2 , the outer surface of the frame  220  may include a recessed portion or scalloping  229  near the retention feature, which provides a finger grip to allow the patient an improved ability to grip the shroud  250  and disengage the retention feature when disengaging the shroud from the frame. 
     1.7 Cushion to Frame Connection 
     As best shown in  FIG. 10-7 , the non-face contacting side of the cushion  40  is connected to frame  20  in a tongue and groove relationship. The tongue  42  of the cushion  40  is inserted within a groove  27  provided along the perimeter of the frame  20 . The tongue and groove relationship may also include a locking lip or sealing lip  44  on the cushion  40 . 
     1.8 Ports 
     As best shown in  FIG. 13-2 , the base of the frame may includes two ports  95  positioned so that in use, oxygen or other breathable gas can be delivered close to the patient&#39;s nares or pressure monitoring equipment can be attached. The ports may also be used to attach additional medical equipment such as pressure or flow sensors. The ports may be selectively closable or sealable by a ports cap. 
     While the invention has been described in connection with what are 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. Also, the various embodiments described above may be implemented in conjunction with other embodiments, e.g., aspects of one embodiment may be combined with aspects of another embodiment to realize yet other embodiments. Further, each independent feature or component of any given assembly may constitute an additional embodiment. In addition, while the invention has particular application to patients who suffer from OSA, it is to be appreciated that patients who suffer from other illnesses (e.g., congestive heart failure, diabetes, morbid obesity, stroke, bariatric surgery, etc.) can derive benefit from the above teachings. Moreover, the above teachings have applicability with patients and non-patients alike in non-medical applications.