Abstract:
A respiratory mask has an adjustable forehead support member that is simple and inexpensive to manufacture. The forehead support member may be adjusted by rotating a forehead pad about an off-center bore or by bending an angular adjustment beam. The mask has a mask cushion with an accordionate membrane having at least two hinged portions. The mask may be constructed with a mask frame, the mask cushion, and the forehead support member molded as one piece.

Description:
CROSS-REFERENCE TO PRIORITY APPLICATION  
       [0001]     The present application claims the benefit of U.S. Provisional Application Ser. No. 60/461,414 filed Apr. 10, 2003, which is hereby incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates to a facial mask with an integral cushion and forehead piece used to supply breathable gas to a wearer&#39;s airways.  
         [0003]     The invention has been developed primarily for use in supporting a nasal mask used in Continuous Positive Airway Pressure (CPAP) treatment of, for example, Obstructive Sleep Apnea (OSA) and other ventilation assistance treatments such as Non-Invasive Positive Pressure Ventilation (NIPPV) and will be described hereinafter with reference to this application. However, it will be appreciated that the invention is not limited to these particular uses.  
       BACKGROUND OF THE INVENTION  
       [0004]     CPAP treatment is a common ameliorative treatment for breathing disorders including OSA. CPAP treatment, as described in U.S. Pat. No. 4,944,310, provides pressurized air or other breathable gas to the entrance of a patient&#39;s airways at a pressure elevated above atmospheric pressure, typically in the range of 4-20 cm H 2 O. It is also known for the level of treatment pressure to vary during a period of treatment in accordance with patient need, that form of CPAP being known as automatically adjusting nasal CPAP treatment, as described in U.S. Pat. No. 5,245,995.  
         [0005]     NIPPV is another form of treatment for breathing disorders that can involve a relatively higher pressure of gas being provided in the patient mask during the inspiratory phase of respiration and a relatively lower pressure or atmospheric pressure being provided in the patient mask during the expiratory phase of respiration. In other NIPPV modes, the pressure can be made to vary in a complex manner throughout the respiratory cycle. For example, the pressure at the mask during inspiration or expiration can be varied through the period of treatment.  
         [0006]     Typically, the ventilation assistance for CPAP or NIPPV treatment is delivered to the patient by way of a nasal mask. Alternatively, a mouth mask full-face mask or nasal prongs can be used.  
         [0007]     In this specification, any reference to CPAP treatment is to be understood as embracing all of the above-described forms of ventilation treatment or assistance.  
         [0008]     A CPAP apparatus broadly includes a flow generator for supplying a continuous source of pressurized air or other breathable gas. Such a flow generator is typically a stand-alone unit having an electric motor driving a blower and is typically controlled by a servo-controller under the control of a microcontroller unit. Alternatively, other supplies of pressurized gas can be used. The flow generator is connected to the mask by a gas supply conduit or tube to supply the pressurized gas to an interior of the mask. The mask or gas supply conduit generally includes a venting system to vent exhalation gases from the interior of the mask to the atmosphere. The mask is normally secured to the wearer&#39;s head by a headgear or straps. The straps are adjusted with sufficient tension to achieve a gas-tight seal between the mask and the wearer&#39;s face. The mask generally includes a forehead support to rest against the user&#39;s forehead to support and stabilize the mask with respect to the user&#39;s face and prevent the mask from exerting undue pressure on the user&#39;s nose when the straps are tensioned. Examples of nasal masks are shown in U.S. Pat. Nos. 4,782,832 and 5,243,971.  
         [0009]     One problem that arises with the use of masks is that a single shape of mask must be utilized for a large variety of users having differently shaped and sized heads and facial regions. Therefore, it is desirable for the forehead support to be adjustable to alter an extension between a forehead contacting portion of the forehead support and the mask frame, thereby accommodating a variety of users with a single mask configuration, while maintaining a comfortable fit and gas-tight seal for each user. Additionally, an adjustable forehead support can be adjusted to position the gas supply conduit in a desired position with respect to the user, such as to prevent the gas supply conduit from contacting the wearer&#39;s forehead or face and causing discomfort to the user.  
         [0010]     Adjustable forehead supports are known. See, for example, the adjustable forehead supports disclosed in U.S. Pat. No. 6,119,693 to Kwok et al. and PCT International Patent Application Publication No. WO 00/78384 to Kwok et al., both assigned to the assignee of the present application. Both references disclose effective, durable forehead support mechanisms. However, these mechanisms require several components that increase the expense of manufacturing such mechanisms and make the mechanisms more appropriate for masks that will be used over an extended period of time, generally 3-6 months. Such mechanisms are relatively costly to use with masks intended for single or short-term use.  
         [0011]     There are circumstances where an inexpensive, disposable short-term use mask is appropriate. For instance, such a mask might be appropriate under CPAP testing conditions where the testing is expected to last only a few days or weeks. Such a mask might also be used for patients admitted to hospitals for short-term stays. Extended use masks require periodic disassembly, cleaning and disinfecting, and reassembly to maintain sanitary conditions. The use of a disposable mask can eliminate such mask maintenance during extended treatment. Instead of performing the mask maintenance at the periodic intervals, a user can just dispose the disposable mask at the proper intervals and use a new disposable mask. However, for it to be generally desirable to use a disposable mask in such extended term treatment, the cost of the mask must be sufficiently low so as to compare favorably economically with the overall cost of an extended use mask, including the cost of the extended use mask, as well as the time required and nuisance of the periodic maintenance of the extended use mask.  
         [0012]     Thus, there is a need for an inexpensive short-term use mask for providing breathable gases to a patient, as during CPAP treatment. To accommodate a large variety of users comfortably with a single mask configuration and maintain a gas-tight seal for each user, the mask should include a simple, easy to use adjustable forehead support mechanism. The mask should be inexpensive enough to be disposable during extended term CPAP treatment while comparing favorably economically to the use of an extended term mask. The mask should also be inexpensive enough to justify single-use. It is an object of the present invention to provide such a mask.  
       SUMMARY OF THE INVENTION  
       [0013]     The present invention addresses the above needs by providing a respiratory mask with an adjustable forehead support that is constructed with few moving parts, and with as many parts as possible molded as one piece or co-molded together in a single process. The present invention provides a mask that is not only low in cost, but also is easy to adjust due to the simplicity of the adjustable forehead support.  
         [0014]     A respiratory mask is provided having a mask frame, a mask cushion attached to the frame and a forehead support member integrally formed with the mask frame. A plurality of strap attachment portions are provided on the mask frame for attaching straps to the respiratory mask to secure the respiratory mask to a head and facial region of a user. The forehead support includes a forehead pad having a bore mounted over a forehead support member. The support pad bore has a number of sides, and the outer surface of the forehead support member has a cross-section with a corresponding number of sides, such that the support pad can be mounted over the forehead support member in a number of distinct angular positions corresponding to the number of sides of the support pad bore. An exterior surface of the support pad has a number of sides corresponding to the number of sides of the support pad bore, each exterior side preferably having a different spacing to an axis of the forehead support member than the other sides. In this manner, a number of different extensions between a forehead-contacting portion of the support pad and the mask frame can be provided by changing the angular position of the support pad with respect to the forehead support member.  
         [0015]     An alternative embodiment of the mask includes a mask frame, molded in a flat configuration, having a cushion supporting portion, an air inlet portion and a forehead support portion. A mask cushion is attached to the mask frame cushion supporting portion. The forehead support portion and mask frame air inlet members are connected to the mask frame cushion supporting portion by hinges such that the air inlet portion can be folded over the cushion supporting portion and the forehead support portion can be folded over the air inlet portion with a cooperative locking mechanism on the mask frame interlocking the components in a final folded configuration ready for wearing. The forehead support portion includes a pair of forehead support adjustment mechanisms adjustable as to height to adjust the extension of a forehead support pad relative to the interlocked mask frame and mask cushion. The mask frame also includes portions for attaching to headgear or straps to secure the mask to the head and facial region of the user.  
         [0016]     A method of manufacturing a respiratory mask is provided including molding integrally in a generally flat configuration, a mask frame having a cushion supporting portion, an air inlet portion and a forehead support portion, with the forehead support portion and mask frame air inlet members being connected to the mask frame cushion supporting portion by hinges such that the air inlet portion can be folded over the cushion supporting portion and the forehead support portion can be folded over the air inlet portion and locked in a final wearable configuration. A mask cushion is also molded to or otherwise attached to the mask frame cushion supporting portion. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]     Preferred embodiments of the invention will now be described, by way of examples only, with reference to the accompanying drawings in which:  
         [0018]      FIG. 1  is a front perspective view of a first embodiment of a mask according to the invention;  
         [0019]      FIG. 2  is a rear perspective view of the mask shown in  FIG. 1 ;  
         [0020]      FIG. 3   a  is an enlarged perspective view of the forehead support of the mask according to the first embodiment of the invention;  
         [0021]      FIG. 3   b  is an exploded view of the forehead support of the mask according to the first embodiment of the invention;  
         [0022]      FIG. 3   c  is a top plan view of the forehead pad of the mask according to the first embodiment of the invention;  
         [0023]      FIGS. 4   a - d  are top plan views of the forehead support according to the first embodiment in each of four adjustable positions;  
         [0024]      FIGS. 5   a - d  are side elevational views of the forehead support according to the first embodiment in each of the four adjustable positions on a user&#39;s forehead;  
         [0025]      FIG. 6  is a top plan view of an alternative embodiment of the forehead pad;  
         [0026]      FIG. 7  is a side elevational view of the mask according to the first embodiment secured to a user;  
         [0027]      FIGS. 8   a - c  are schematic drawings depicting the interaction between the cushion and a user&#39;s facial region;  
         [0028]      FIG. 9  is a front perspective view of an alternative embodiment of a mask according to the invention;  
         [0029]      FIG. 10  is a rear perspective view of the mask shown in  FIG. 9 ;  
         [0030]      FIG. 11  is a rear perspective schematic view of an alternative embodiment of the present invention;  
         [0031]      FIG. 12  is a rear elevational view of an alternative embodiment of the present invention;  
         [0032]      FIGS. 13   a - d  are partial schematic top plan views of an alternative embodiment of a forehead support of the present invention;  
         [0033]      FIGS. 14   a - d  are partial schematic top plan views of an alternative embodiment of a forehead pad of the present invention;  
         [0034]      FIGS. 15   a - c  are partial elevational views of an alternative embodiment of the forehead support of the present invention;  
         [0035]      FIGS. 16   a  and  16   b  are partial side elevational schematic views of an alternative embodiment of the forehead support of the present invention;  
         [0036]      FIG. 17  is a front perspective view of another embodiment of the invention, in a flat, unfolded state, wherein the respiratory mask is molded as a single piece in a generally flat configuration to be folded together for assembly;  
         [0037]      FIG. 17   a  is a rear perspective view of the embodiment configuration of  FIG. 17 ;  
         [0038]      FIG. 18  is a rear perspective view of the embodiment of  FIG. 17  wherein the air inlet portion has been folded onto the cushion supporting portion;  
         [0039]      FIGS. 19   a - c  show top perspective detail views of a forehead support adjustment mechanism of the embodiment of  FIG. 17  with progressive stages of positioning of the forehead support adjustment mechanism;  
         [0040]      FIGS. 20   a - c  show bottom perspective detail views corresponding to  FIGS. 19   a - c;    
         [0041]      FIG. 21  is a rear perspective view of the embodiment of  FIG. 17  with the forehead support adjustment mechanisms assembled;  
         [0042]      FIG. 22  is a rear perspective view of the embodiment of  FIG. 21  with the forehead support adjustment mechanisms folded onto the forehead support portion;  
         [0043]      FIG. 23  is a front perspective view of the embodiment of  FIG. 17  in a fully assembled state (less straps and air hose);  
         [0044]      FIGS. 24   a - b  are side elevational views of the embodiment of  FIG. 17  showing two different forehead support adjustments;  
         [0045]      FIG. 25  is a side elevational view of a further embodiment of the present invention incorporating the folding frame design of  FIGS. 17-24  and the forehead support of  FIGS. 1-16 ;  
         [0046]      FIG. 26  is a front, top perspective view of the embodiment of  FIG. 25 ;  
         [0047]      FIG. 27  is a rear, bottom perspective view of the embodiment of  FIG. 26 . 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0048]     In the included figures a nasal mask is depicted, but the current invention is not intended to be limited to nasal masks. The aspects of the current invention are equally applicable to a mouth or full-face mask.  
         [0049]      FIGS. 1 and 2  show front and rear perspective views of an embodiment of the present invention. A nasal mask  10  has a mask frame  20 , strap attachment portions  30 , a forehead support  40  including a forehead support member  42  and a forehead pad  50 , and a mask cushion  60 . The mask also has a single air inlet tube  70  mounted on the mask frame  20  for supplying pressurized gas to an interior of the mask  10 . Pressurized gas is supplied to the mask  10  by an air supply conduit (not shown) connected between the air inlet tube  70  and a pressurized air supply (not shown). As is known, an exhaust vent can be provided on the mask  10  or air supply conduit for exhausting exhalation gases from an interior of the mask. Other embodiments may have vents, elbows, pressure ports, or other attachments for items such as a sense tube or oxygen supply port as further options. There may also be further attachment portions for straps or other types of headgear.  
         [0050]      FIG. 3   a  is an enlarged perspective view of the forehead pad  50  and  FIG. 3   b  is an exploded view of the mask frame  20 , forehead support member  42  and the forehead pad  50 . In this embodiment, forehead support member  42 , is attached to and extends upwardly from mask frame  20 . Forehead support member  42  includes a lower supporting surface  43 , an upper supporting surface  44  and an upright column  46  positioned between the supporting surfaces  43  and  44  having four exterior sides  45 . Two upper strap attachment portions  49  are mounted on opposing sides of an upper portion of the forehead support member  42  and are reinforced by brace member  47  attached to and extending between an upper portion of the upper strap attachment portions  49  and the upper portion of the forehead support member  42 . A position indicating marker  48  is attached to the brace member  47 . In the preferred embodiment, upright column  46  is solid to add strength to the forehead support member  42 . In alternative embodiments, the upright column  46  can be hollow or can have a strengthening insert molded therein.  
         [0051]     In this embodiment, the forehead pad  50  is an elastomeric pad, having four exterior sides  52 , denoted individually as sides  521 ,  522 ,  523  and  524 , and an off-center bore  56 . The off-center square bore  56  is defined by four inner surfaces  561 ,  562 ,  563 , and  564 , corresponding to sides  521 ,  522 ,  523  and  524 , respectively. The bore  56  is configured and sized so as to be able to mount over the upright column  46  in a mating fashion. Upper supporting surface  44  and lower supporting surface  43  are sized to be somewhat larger than the size of bore  56  so that when the forehead pad is mounted over the forehead support member  42 , the upper and lower supporting surfaces will retain the forehead pad in place on the forehead support member  42 . The elasticity of the forehead pad  50  allows the forehead pad  50  to pass over the larger upper supporting surface  44  when installing or removing the forehead pad  50  with respect to the forehead support member  42 .  
         [0052]     Since the bore  56  is off-center, a distance between an axis of the bore  56  and the exterior sides  52  is different for each side  521 ,  522 ,  523 , and  524 , which in the embodiment shown, increases from side  521  to side  522  to side  523  to side  524 . See  FIG. 3   c , which shows a distance d4 for side  524  greater than a distance d3 for side  523  greater than a distance d2 for side  522  greater than a distance d1 for side  521 . In this embodiment, the forehead pad can be mounted on the forehead support member in four different angular positions. In each angular position, a different side  52  will be facing toward the user to contact the user&#39;s forehead. Since the distance between each side  52  and the axis of the bore  56  is different, changing the angular position of the forehead pad  50  with respect to the forehead support member will alter the distance between the forehead support member  42  and the user&#39;s forehead, allowing the forehead support  40  to be adjusted as desired for each user.  
         [0053]     Each exterior side  52  has a corresponding position indicator  54 , denoted individually as position indicators  541 ,  542 ,  543  and  544 , corresponding to sides  521 ,  522 ,  523  and  524 , respectively. These position indicators  54  are depicted as rounded projections, which provide a visual and tactile indicator of the position of the forehead pad  50  when mounted on the forehead support member. As shown, position indicator  541  includes one raised projection, position indicator  542  includes two raised projections, position indicator  543  includes three raised projections and position indicator  544  includes four raised projections. Alternatively, the position indicators can be in the form of printed markings, notches, labels or other forms of visual and/or tactile indicators. The user is able to determine which angular position the forehead pad is in by determining which position indicator  54  is aligned with the position indicating marker  48 .  
         [0054]     The bore  56  need not be of continuous cross-section, and need not extend from one end of the forehead pad  50  to the other, but rather may be open at only one end. Its configuration may also be tapered or have other provisions in order to effectively lock the forehead pad  50  to the mask  10  so that it will resist moving from the chosen position when in use. Such locking effect may include the provision of stepped configuration along the forehead support member  42  or the bore  56  such that there is engagement and interference between the two components. Alternative mechanisms for locking the adjusted forehead pad  50  to the forehead support member  42  can also be used.  
         [0055]      FIGS. 4   a, b, c , and  d  are top plan view of the mask  10  and  FIGS. 5   a, b, c  and  d  are side elevational views of the mask  10  positioned on a user, respectively illustrating the four angular positions of the forehead pad according to this embodiment of the invention.  FIGS. 4   a  and  5   a  illustrate the first angular position, appropriate for a user having a protuberant forehead. The forehead pad  50  has been rotated counterclockwise from the first position to the second position illustrated in  FIGS. 4   b  and  5   b . This position is appropriate for a less protuberant forehead than in position  1 . The forehead pad  50  has been further rotated counterclockwise from the second position to the third position illustrated in  FIGS. 4   c  and  5   c . This position is appropriate for a slightly receding forehead. Finally, the forehead pad has been rotated counterclockwise from the third position to the fourth position illustrated in  FIGS. 4   d  and  5   d . This position is appropriate for users having a more receding forehead than illustrated in  FIG. 5   c . Although only four positions are shown, fewer or greater than four positions can be provided by suitably altering the number of sides  45 ,  52  and  56 , with a distance between each side  52  and an axis of the forehead support member  42  being different.  
         [0056]     In an alternative embodiment shown in  FIG. 6 , the forehead pad  50  can be cam-shaped and have a toothed off-center bore  56  adapted to engage a similarly toothed forehead support member  42  to provide a greater resolution of adjustment, Alternatively, if pad  50  is retained to support  42  by press fit, a generally continuously variable adjustability of the distance from the forehead contacting surface of the pad  50  to the mask frame  20 .  
         [0057]      FIG. 7  illustrates a nasal mask  10  of the present invention being worn by a user. Mounting straps  32  are attached to the strap attachment portions  30 , to attach the nasal mask to the user&#39;s head. The forehead pad  50  contacts the forehead. The mask cushion  60  seals the mask frame  20  to the facial region of the user. The mask cushion  60  is shaped to substantially conform to the facial region of the user. However, the shape of the facial regions of different users varies and the adjustable position of the forehead pad  50  may not be optimal for all users. Therefore, it is desirable for the mask cushion  60  to be flexible and resilient to seal the mask frame  20  to the facial regions of a variety of users.  
         [0058]      FIGS. 8   a ,  8   b  and  8   c  are schematic diagrams depicting the accordionate configuration and behavior of the mask cushion  60 . Cushion  60  includes a face contacting portion  66  connected to a main body  68  of the cushion  60  by cushion hinged portions  62  and  64 . If a portion of the mask frame  20  is close to the facial region of the user, the included angles of the two hinged portions  62 ,  64  will decrease, allowing the face contacting portion  66  to draw closer to the mask frame without causing discomfort to the user. If a portion of the mask frame  20  is not close to the facial region of the user, the included angles of the two hinged portions  62 ,  64  will increase, allowing the face contacting portion  66  to extend from the mask frame while continuing to maintain a seal with the facial region of the user.  FIG. 8   a  depicts a condition in which the angle between the mask frame  20  and the facial region of the user is substantially optimized.  FIG. 8   b  depicts a condition in which the upper portion of the mask frame  20  is closer to the facial region of the user than the lower portion, and the upper portion of the face contacting portion  66  of the cushion is closer to the cushion main body  68  than the lower portion of the face contacting portion  66  to accommodate for this.  FIG. 8   c  depicts a condition opposite to the condition in  FIG. 8   b  in which the lower portion of the mask frame  20  is closer to the facial region of the user than the upper portion, and the lower portion of the face contacting portion  66  of the cushion is closer to the cushion main body  68  than the upper portion of the face contacting portion  66  to accommodate for this.  
         [0059]      FIGS. 9 and 10  show front and rear perspective views of an alternative embodiment of the present invention. The nasal mask  10  of this embodiment is similar to the embodiment shown in  FIGS. 1 and 2  but has a mask frame  20  having a slightly different shape and configuration to improve moldability of the frame, as well as to improve the aesthetic appearance of the frame. This embodiment also has strap attachment portions  30 , a forehead support  40  including a forehead support member  42  and a forehead pad  50 , a mask cushion  60  and a single air inlet tube  70  mounted on the mask frame  20  for supplying pressurized gas to an interior of the mask  10 .  
         [0060]      FIG. 11  is a rear perspective schematic view of an alternative embodiment of the present invention. In the nasal mask  10  of this embodiment, an air inlet tube  72  is mounted to the top of the mask frame  20  and has a square outer cross-section so as to act as the forehead support member  42  of the previous embodiments. As with the previous embodiments, the forehead pad  50  can be placed over the air inlet tube in a plurality of different angular positions to alter a distance between the air inlet tube/forehead support member  72  and allow the mask to be adjusted for each user.  
         [0061]      FIG. 12  is a rear elevational view of an alternative embodiment of the present invention.  
         [0062]      FIGS. 13   a - d  are partial schematic top plan views of an alternative embodiment of the forehead support  40 . In this embodiment, the forehead support member  42  is configured to have a U-shaped cross-section. An open end of the U-shaped cross-section is shown as facing toward the user but can be oriented away from the user as well. The U-shape can reduce material required for the forehead support member  42  while retaining the necessary strength.  FIGS. 13   a - d  show the different angular positions of the forehead pad  50  corresponding respectively to the positions shown in  FIGS. 4   a - d  and  5   a - d.    
         [0063]      FIGS. 14   a - d  are partial schematic top plan views of an alternative embodiment of the forehead pad  50  positioned on the forehead support member  42  of the embodiment shown in  FIGS. 13   a - d . The forehead pad  50  of this embodiment is not shaped as a rectangle with flat exterior sides. Rather, each exterior side  52  of the forehead pad is generally U-shaped in cross-section with the open end facing outward. Although the bore  56  is positioned generally in a center of a central portion  59  of the forehead pad  50 , the two legs  58  of the U-shaped cross-section of each exterior side  52  have a different height. Because of this configuration, the adjustment of the forehead support  40  can be altered as described above by changing the angular orientation of the forehead pad  50  on the forehead support member  42 .  FIGS. 14   a - d  show the different angular positions of the forehead pad  50  corresponding respectively to the positions shown in  FIGS. 4   a - d ,  5   a - d  and  15   a - d . This configuration of forehead pad  50  can reduce the amount of material required to make the pad and can also minimize an area of contact of the forehead pad  50  with the user to increase the comfort of the user.  
         [0064]      FIGS. 15   a - c  are partial elevational views of an alternative embodiment of the forehead support  40 . In this embodiment, the forehead support member  42  (or air inlet tube  72 ) has an extended height to provide for a plurality of different elevational positions for the forehead pad  50 . In the embodiment shown, the forehead support member  42  includes three separate elevational adjustment positions  120  bounded on each side by position retaining flanges  122 . The forehead pad can be moved to any one of the elevational adjustment positions  120  to provide a desired elevational position of the forehead pad  50  on the nasal mask  10  with respect to the user. The position retaining flanges  122  are larger than the bore  56  in the forehead pad  50  to prevent the forehead pad  50  from moving undesirably up and down the forehead support member  42  once it has been adjusted but due to the flexibility of the forehead pad  50 , it can be moved over a position retaining flange  122  by applying sufficient force to the forehead pad  50 . The force required to move the forehead pad to a different elevational adjustment position can be altered by altering the size of the position retaining flanges  122  with respect to the bore  56  and/or by changing the flexibility of the forehead pad  50 . Three elevational positions of the forehead pad  50  are shown respectively in  FIGS. 15   a ,  15   b  and  15   c . The number of elevational adjustment positions  120  can be altered as desired. In a modified version of this embodiment, retaining flanges can be positioned on the forehead pad  50  to engage grooves or other structure on the forehead support member  42 .  
         [0065]      FIGS. 16   a  and  16   b  are partial side elevational schematic views of an alternative embodiment of the forehead support  40 . In this embodiment, the forehead support member  42  is tapered along its length. Because the forehead pad  50  is flexible, it can be moved to a desired position along the forehead support member and the forehead support member will correspondingly expand the bore  56  of the flexible forehead pad  50 , creating a friction fit between the forehead pad  50  and the forehead support member  42  that will retain the forehead pad  50  in the adjusted position.  FIG. 16   a  shows the forehead pad  50  in an elevated position with respect to the forehead support member  42  where there is a minimal friction fit and  FIG. 16   b  shows the forehead pad  50  in a lowered position with respect to the forehead support member  42  where there is an increased frictional fit. Thus, this embodiment allows infinite elevational positioning of the forehead pad  50  along a given range of the forehead support member  42 , as opposed to the discrete positioning provided by the embodiment of  FIGS. 15   a - c . The magnitude of retaining force of the friction fit between the forehead pad  50  and the forehead support member  42  can be altered by altering the size and shape of the bore  56 , the flexibility, material or surface finish of the forehead pad  50 , or the taper, size, shape, material or surface finish of the forehead member  42 . In one embodiment, a retaining flange can be provided at a bottom portion of the forehead support member  42  to provide a positive bottom stop to the elevational adjustment of the forehead pad  50 .  
         [0066]      FIGS. 17-24  illustrate another embodiment of the invention. In this embodiment, the respiratory mask is molded as a single piece in a generally flat configuration and folded together for assembly.  FIG. 17  is a front perspective view of the mask frame in the flat, unfolded state. The mask frame  20  includes a cushion supporting portion  80 , an air inlet portion  90  and a forehead support portion  100 . An integral hinge  92 , also called a “living hinge”, is molded between the cushion supporting portion  80  and the air inlet portion  90 . An integral hinge  102  is molded between the cushion supporting portion  80  and the forehead support portion  102 . In this manner, both the air inlet portion  90  and the forehead support portion  102  can be folded with respect to the cushion supporting portion  80 . A sealing member  82  (see  FIG. 17   a ) is provided around a periphery of the cushion supporting member  80  and adapted to sealingly engage the air inlet portion  90  such that when the air inlet portion  90  is folded over onto the cushion supporting portion  80 , a gas-tight seal is formed between those two portions to seal an interior of the mask  10 . A latch mechanism  94  is attached to a distal edge of the air inlet portion  90  and is adapted to engage a lip  84  on the cushion supporting portion when the two components are folded together to latch the two components in the folded position. See  FIG. 18 , which is a rear perspective view of the mask  10  wherein the air inlet portion  90  has been folded onto the cushion supporting portion  80  and latched in place.  
         [0067]     The forehead support portion  100  has a main body portion  104  and a forehead pad mounting portion  108  interconnected by an offset portion  106  to offset the forehead pad  110  with respect to the main body portion  104 . The degree of offset, if any, can be altered as desired for the specific application. Rib  109  between the main body portion  104  and the offset portion  106  adds strength to the forehead support portion  100 .  
         [0068]     The forehead support portion  100  can utilize the forehead support mechanism  40  discussed above, as shown in  FIGS. 25-27  and discussed in more detail below. Alternatively, a nonadjustable forehead pad  110  can be attached to the forehead support portion  100  using methods described herein or molded integrally therewith. In such an embodiment, it is desirable to provide an alternative mechanism for adjusting the forehead pad with respect to the mask frame  20 . In one such embodiment, the forehead support portion  100  is provided with a pair of forehead support adjustment mechanisms  130 . Each forehead support adjustment mechanism  130  is preferably molded integrally with the forehead support portion  100 , although this is not required, and includes an elongated adjustment channel member  132  attached at one end to the forehead support portion  100  by hinge  134 . A foldable adjustable height member  138  is attached at another end of the adjustment channel member  132  by hinge  136 . The adjustable height member  138  preferably, though not necessarily, includes a side segment  140 , top segment  144  and side segment  148  connected together by hinges  142  and  146 , respectively, so as to be foldable with respect to one another. See  FIGS. 17-18 . Alternatively, top member  144  and hinge  146  can be omitted so that side segment  140  is directly connected to side segment  148  by hinge  142 . See  FIGS. 19-24 . An adjustment tab  152  is connected to side member  148  by hinge  150  and is configured and arranged for adjustable engagement with adjustment channel member  132 . See  FIGS. 19   a - c , which show top perspective detail views of the forehead support adjustment mechanism  130  with progressive stages of positioning of the forehead support adjustment mechanism  130 , and  20   a - c , which show corresponding bottom perspective detail views thereof.  
         [0069]     Each elongated adjustment channel member  132  includes a channel  154  including a tab insertion portion  156  and an adjustment portion  158 . The adjustment portion  158  of channel  154  includes a pair of sets of uniformly spaced opposed detent slots  160  extending from side walls of the channel  154  inward toward one another. The adjustment tab  152  includes a top retaining portion  162  connected to an adjustment fixing portion  164  connected to a bottom retaining portion  166 . See  FIGS. 19 and 20 . The bottom retaining portion  166  can be grooved (see  FIGS. 19   a  and  20   b ), ridged or otherwise textured, as can top retaining portion  162  to increase a user&#39;s grip on the adjustment tab  152  during adjustment. The adjustment fixing portion  164  includes a pair of sets of outwardly facing detent lugs  168  spaced, configured and dimensioned so as to be able to uniformly engage the detent slots  160  of channel  154  in a temporarily fixed adjustment position until sufficient force is applied to move the detent lugs  168  with respect to the detent slots  160 .  
         [0070]     In a preferred embodiment, a width of the bottom retaining portion  166  of the adjustment tab  152  is less than or equal to a width of the tab insertion portion  156  of the channel  154  and a width of the top retaining portion  162  of the adjustment tab  152  is greater than a width of the tab insertion portion  156  of the channel  154  so as to permit insertion of the adjustment tab  152  into the tab insertion portion  156  (see  FIGS. 19   a  and  20   a ) until the top retaining portion  162  of the adjustment tab  152  contacts the adjustment channel member  132  to prevent further insertion (see  FIGS. 19   b  and  20   b ). On the other hand, the width of the bottom retaining portion  166  of the adjustment tab is greater than a minimum width between the opposing sets of detent slots  160  of channel  154  so that when the adjustment tab  152  is moved along the length of the channel  154  from out of the tab insertion portion  156  into the adjustment portion  158  (see  FIGS. 19   c  and  20   c ), the detent slots  160  engage the bottom retaining portion  166  of adjustment tab  152  to retain adjustment tab  152  in the channel  154  until the adjustment tab  152  is again moved lengthwise along the channel  154  back into the tab insertion portion  156  (see  FIGS. 19   b  and  20   b ). Adjusting the position of the adjustment tab  152  along the length of the channel  154  allows the overall height of the adjustable height member  138  to be altered with respect to the adjustment channel member  132  and thus, the forehead support portion  100  of the mask, to adjust the height of the forehead support pad, as will be discussed below in further detail.  FIG. 21  is a rear perspective view of the mask of this embodiment, with the adjustment tabs  152  positioned in the adjustment portions  158  of the channels  154 , respectively.  
         [0071]     A minimum inner width between the closest portions of opposed sets of the detent slots  160  of the channel  154  is somewhat smaller than a maximum exterior width of opposed sets of the detent lugs  168  of the adjustment tab  152  so that engagement between the detent slots  160  of channel  154  and the detent lugs  168  of the adjustment tab  152  will temporarily fix the adjustment tab  152  in a desired lengthwise position in the adjustment portion  158  of the channel  154  until sufficient force is applied to overcome such engagement. The force required is determined by a trade-off between balancing the minimum force required to maintain the adjustment tab  152  in a desired adjusted position in the channel  154  when the mask is being worn by the user with the maximum force desired to allow the user the change the adjustment of the adjustment tab  152 . These forces can be altered by altering the magnitude of the engagement between opposing detent slots/detent lugs of the channel  154  and adjustment tab  152 , respectively, by altering dimensions of the respective detent slot/detent lugs and altering the number and/or shape of the respective detent slots/detent lugs, as well as by altering the material and/or rigidity of the respective detent slots/detent lugs. The positioning of the detent slots and detent lugs on the respective components can be reversed and alternative detent configurations can be used.  
         [0072]      FIG. 22  is a rear perspective view of the mask of this embodiment where the forehead support adjustment mechanisms  130 , through hinges  134 , have been folded down onto a rear surface of the forehead support portion  100  of mask frame  20 . Forehead support portion  100  can include stabilizing portions  170  (see  FIG. 21 ), such as raised ridges or walls, slots or other structure, to engage the adjustment channel members  132  or other portions of the forehead support adjustment mechanisms  130  to provide lateral and other support to the mechanisms  130  when they are in their final folded position. At this point, the cushion supporting portion  80 /air inlet portion  90  folded subassembly can be folded toward the forehead support portion  100  of the mask until subassembly comes into contact with the upstanding portion of the adjustable height members  138 , with the adjustable height members  138  positioned on opposing sides of the cushion supporting portion  80 /air inlet portion  90  folded subassembly and between the forehead support portion  100  and the cushion supporting portion  80 /air inlet portion  90  folded subassembly. See  FIGS. 23-24 . In the shown embodiment, the adjustable height members  138  are shown as contacting a surface  96  of the air inlet portion  90 , although this can be altered as desired so that the adjustable height members  138  contact other portions of the cushion supporting portion  80 /air inlet portion  90  folded subassembly.  
         [0073]     By altering the lengthwise positions of the adjustment tabs  152  in the adjustment portions  158  of the channels  154 , the height of the adjustable height members  138  can be adjusted with respect to the forehead support portion  100 , thereby altering an angle θ (at hinge  102 ) between the forehead support portion  100  and the cushion supporting portion  80 /air inlet portion  90  folded subassembly, and thus, altering a corresponding relative height between the forehead pad  110  and the cushion  60 . Compare  FIGS. 24   a  and  24   b . The height of adjustable height member  138  is higher in  FIG. 24   a  because the adjustment tab  152  is positioned in the adjustment portion  158  of channel  154  nearer hinge  136  in  FIG. 24   a , thereby resulting in the forehead pad  110  being relatively positioned more toward the front of the mask than in  FIG. 24   b  to better accommodate a user having a more protuberant forehead. For instance, the adjustment shown in  FIG. 24   a  corresponds more with a user as shown in  FIG. 5   b  while the adjustment shown in  FIG. 24   b  corresponds more with a user as shown in  FIG. 5   c . The user can easily adjust the relative position of the forehead pad  110  through manual adjustment of the height of the adjustable height member  138  by moving the adjustment tab  152  in the channel  154 . In this embodiment, the angle of the forehead pad  110  will change with respect to the user within the range of adjustment provided. However, this is accommodated by the resiliency of the forehead pad and can be altered within certain parameters by altering the angle of upright portion  46 , and/or a user-contacting portion of the forehead pad  110  with respect to a plane of forehead support portion  100 . Alternatively, hinge  102  can be replaced by a double hinge to minimize relative angle changes in the forehead pad  110  as the relative height of the forehead pad is adjusted. Alternatively, the forehead pad can have a cylindrical surface to accommodate varying angles of contact with the forehead.  
         [0074]     Strap attachment portions  49  and  30  are provided on the forehead support portion  100  and the cushion supporting portion  80  or air inlet portion  90  for attaching to headgear or straps to secure the mask to the head and facial region of the user. Although the adjustment mechanisms  130  are shown as being attached to the forehead support portion  100 , alternative embodiments can be constructed by attaching the adjustment mechanisms to the cushion support portion  80  and/or the air inlet portion  90  and contacting against the forehead support portion  100 . Alternatively, the use of a single adjustment mechanism or three or more adjustment mechanisms is contemplated, as well as the use of separately molded adjustment mechanisms.  
         [0075]      FIGS. 25-27  show a further embodiment of the present invention incorporating aspects from the mask of  FIGS. 17-24  and the forehead support of  FIGS. 1-16 . In this embodiment, the forehead support portion supports a forehead support member  42  and forehead pad similar to the embodiments shown in  FIGS. 1-16 . This embodiment also shows use of the mask frame and forehead adjustment mechanisms of the embodiment shown in  FIGS. 17-24 . Thus, this embodiment gives a wider range of forehead pad adjustability than either of the other two groups of mask embodiments alone. In a modification of this embodiment, the forehead support adjustment mechanisms  130  could be removed or replaced by generally fixed members to combine the one-piece, disposable frame aspects of  FIGS. 17-24  with the forehead pad adjustment of  FIGS. 1-16 .  
         [0076]     In order to enable the mask to be molded as one piece, allowance must be made for variation in the desirable characteristics of the different sections of the molding. For example, the mask frame  20  must be rigid, but the mask cushion  60  must be flexible enough to provide comfort and good sealing properties while the forehead support member  42  must be resilient. To make the mask out of one material, such as polypropylene, while providing the differing levels of flexibility desired in the various components, the molding process can provide a changing gradient of material density, as can be achieved by forms of gas assisted injection molding, resulting in a change in rigidity. Another option, which could be used in addition to the changing gradient of material density, is the use of a continuous gradient of material thickness or by stepped contours or introduction of ribbing to provide reinforcement in certain areas where more rigidity is required.  
         [0077]     An alternative construction can involve the incorporation of a separate mask cushion  60  to the mask frame  20 . The mask cushion  60  can be made of material different to the mask frame  20  or can be made of the same material and may be attached by using any of the methods known in the art, such as friction fit, strapping, clips, or adhesive. Alternatively, the mask cushion  60  can be overmolded onto the mask frame or co-molded with the mask frame  20  in accordance with methods known in the art of molding. In such examples, placement of appropriate channeling in the mask frame  20  allows for bleed-through of cushion molding material so as to achieve enhanced attachment of the mask cushion  60  to the mask frame  20 . This can be especially desirable if the mask cushion  60  is made of a material that does not readily form a chemical bond with the material of the mask frame  20 . This technique may also be used to provide even softer material between the mask frame  20  and the user at certain contact points, a decorative effect, or visually vivid and tactile labeling. The key polymers capable of incorporating living hinges and which would be suited to this application are polypropylene and styrene-butadiene copolymers such as K-Resin®.  
         [0078]     It is intended that various features of the various embodiments described above can be combined to create different embodiments of the nasal mask of the present invention. The embodiments describe above are exemplary only and are not exhaustive of the scope of the invention. It is also intended that changes and modifications can be made to the embodiments described above without departing from the scope of the invention.