Abstract:
A forehead support for a facial mask is adapted to be moveable between a first position with respect to a frame of the mask and a second position with respect to the frame. The forehead support includes a biasing mechanism that urges the forehead support in the second position. A method of positioning a forehead support with respect to a frame of a patient interface includes positioning the forehead support and patient interface assembly on a face; disengaging a forehead support locking mechanism; allowing the forehead support to move from a first position to a second position; and engaging a forehead support locking mechanism.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to U.S. Provisional Application 60/945,380, filed Jun. 21, 2007, the entire contents being incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    Sample embodiments of the present invention relates to an automatically adjusting mask stabilizer for a facial mask used to supply breathable gas to a wearer&#39;s airways. 
         [0003]    Sample embodiments of the invention have been developed primarily for use in supporting a mask used in Continuous Positive Airway Pressure (CPAP) treatment of, for example, Obstructive Sleep Apnea (OSA) and other ventilatory 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 sample embodiments of the invention are not limited to these particular uses and are also suitable for use with, for example, nasal (nose only), mouth only, or full-face (i.e. nose and mouth) masks, or prongs, nozzles, puffs or the like. 
       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 4-20 cm H 2 O. 
         [0005]    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. 
         [0006]    NIPPV is another form of treatment for breathing disorders which 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. 
         [0007]    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. 
         [0008]    Typically, the ventilatory assistance for CPAP or NIPPV treatment is delivered to the patient by way of a nasal mask. Alternatively, a mouth mask or full face mask or nasal prongs can be used. In this specification any reference to a mask is to be understood as incorporating a reference to a nasal mask, mouth mask, full face mask or nasal prongs. 
         [0009]    In this specification any reference to CPAP treatment is to be understood as embracing all of the above described forms of ventilatory treatment or assistance. 
         [0010]    A CPAP apparatus broadly comprises a flow generator constituted by a continuous source of air or other breathable gas such as a hospital piped supply or a blower. In the latter case, an electric motor drives the blower and is typically controlled by a servo-controller under the control of a microcontroller unit. In either case, the gas supply is connected to a conduit or tube which in turn is connected to a patient nasal or full-face mask which incorporates, or has in close proximity, an exhaust to atmosphere for venting exhaled gases. Examples of prior art nasal masks are shown in U.S. Pat. Nos. 4,782,832 and 5,243,971. 
         [0011]    The supply conduit delivers gas into a chamber formed by walls of the mask. The mask is normally secured to the wearer&#39;s head by straps. The straps are adjusted to pull the mask against the face with sufficient force to achieve a gas tight seal between the mask and the wearer&#39;s face. 
         [0012]    A problem that arises with the use of the existing masks is that in order for the straps to be tight, the mask is compressed against the wearer&#39;s face and may push unduly hard on the wearer&#39;s nose or face. Additionally, the mask may move around the wearer&#39;s face. Thus, there has been hitherto provided a stabilizing support, such as a forehead support, which provides a support mechanism between the mask and the forehead. This forehead support prevents both the mask from pushing too strongly against the wearer&#39;s nose and/or facial region (by distributing forces) as well as minimizing movement of the mask with the addition of a contact point between the mask and the wearer&#39;s head thereby reducing uncomfortable pressure points. Additionally, the forehead support can be arranged to prevent the gas supply conduit from contacting the wearer&#39;s forehead or face. 
         [0013]    In order to fit a mask system to a patient, the cushion is fitted to the face of the patient and an ideal position is found. The ideal position is one in which a good seal is formed and the mask feels comfortable to the patient. Once the ideal position is found, the forehead support is brought into contact with the patient&#39;s head to provide stability to the ideal position of the mask relative to the patient&#39;s head. 
         [0014]    Another problem that arises with the use of existing masks is that many forehead supports require two hands to adjust. One hand is typically used to secure the mask, while the other hand is used to adjust the position of the forehead support. Such an adjustment may require too high a level of dexterity for some patients or clinicians. In addition, existing mask systems provide discrete adjustment points for the position of the forehead support, leading to a trial and error process in determining the ideal position. It is also difficult to determine how many discrete positions should be provided. If too few discrete positions are provided, it may not be able to set or lock the forehead support in a position that truly stabilizes the mask in the ideal position. If too many discrete positions are provided, the fitting may be complicated by the patient being unable to decide which position stabilizes the mask in the ideal position. 
         [0015]    An even further problem with the use of existing masks is that the adjustment of the forehead support changes the inclination between the forehead support pads and the patient&#39;s forehead. For example, the forehead support shown in U.S. Pat. No. 6,532,961 includes a frame that is movably (e.g. pivotably) adjustable with respect to the mask. Pivoting of the forehead support during the adjustment process changes the inclination between the pad and the patient&#39;s forehead and may result in an undesirable change in the amount of support provided by the forehead support. 
         [0016]    Thus, a need has developed in the art to address one or more of the above problems. 
       SUMMARY OF THE INVENTION 
       [0017]    One aspect of the invention relates to an auto-adjusting mask stabilizer that permits automatic and/or semi-automatic adjustment of a stabilizer (e.g., a forehead support or facial support) for a mask with a minimal level of dexterity and in a shorter amount of time than is currently possible. 
         [0018]    Another aspect of the invention relates to an auto-adjusting mask stabilizer that has fewer parts, is less complex, and is of reduced overall dimensions than currently available stabilizers and/or supports. 
         [0019]    Still another aspect of the present invention relates to an auto-adjusting mask stabilizer that permits the determination of the ideal mask position, based on comfort and seal, and securement of the ideal position in a shorter amount of time and with less effort than is currently possible. 
         [0020]    Yet another aspect of the present invention relates to an auto-adjusting mask stabilizer that may be operated with one hand. 
         [0021]    An even further aspect of the present invention relates to an auto-adjusting mask stabilizer that maintains an angle of inclination between the stabilizer and the patient&#39;s forehead regardless of the relative position of the stabilizer to the mask. 
         [0022]    Another aspect of the present invention relates to an auto-adjusting mask stabilizer that permits the mask stabilizer to be locked in a plurality of positions, including in continuously variable positions. 
         [0023]    According to one embodiment of the invention, a forehead support for a facial mask is provided. The mask includes a frame, and the forehead support is adapted to be moveable between a first position with respect to the frame and a second position with respect to the frame. The forehead support comprises a biasing mechanism that urges the forehead support in the second position. 
         [0024]    According to another embodiment of the invention, a mask assembly comprises a frame, a forehead support, and a spring mechanism. The forehead support is free to move between a first position and a second position and the spring mechanism is arranged to direct the forehead support to the second position. 
         [0025]    According to still another embodiment of the invention, a stabilizer for a patient interface is provided. The patient interface includes a frame, and the stabilizer is adapted to be moveable between a first position with respect to the frame and a second position with respect to the frame. The stabilizer comprises a biasing mechanism that urges the stabilizer into the second position. 
         [0026]    According to a further embodiment of the invention, a method of positioning a forehead support with respect to a frame of a patient interface is provided. The method comprises (i) positioning the forehead support and patient interface assembly on a face; (ii) disengaging a forehead support locking mechanism; (iii) allowing the forehead support to move from a first position to a second position; and (iv) engaging a forehead support locking mechanism. 
         [0027]    According to yet another embodiment of the invention, a mask assembly comprises a mask frame; a cushion attached to the frame and adapted to contact the face of a patient in a substantially airtight manner; and a stabilizer element connected to and translatably movable with respect to the mask frame. An inclination angle between the stabilizer element and the mask frame remains constant as the stabilizer translates with respect to the frame. 
         [0028]    According to an even further embodiment of the invention, a method of fitting a mask assembly to a patient&#39;s face is provided. The mask assembly comprises a mask frame, a cushion attached to the mask frame, a stabilizer element supported by the mask frame for translation with respect to the mask frame, a biasing element that biases the stabilizer element with respect to the mask frame, and a lock mechanism that locks the stabilizer element at a position relative to the mask frame against the bias of the biasing element. The method comprises placing the cushion against the patient&#39;s face to establish a substantially airtight seal at a first comfortable position; unlocking the lock mechanism to permit the biasing element to bias the stabilizer element against the patient&#39;s face when the cushion is in the first comfortable position; and locking the lock mechanism to lock the stabilizer element and stabilize the cushion at the first comfortable position. 
         [0029]    According to another embodiment of the invention, a stabilizer for a mask assembly comprises a mask frame extension adapted to be connected to a mask frame of the mask assembly; a pad support element translatably supported by the mask frame extension, the pad support element being configured to support a pad that, in use, contacts a face, e.g. cheeks or upper lip, of a wearer of the mask assembly; and a biasing element that biases the stabilizer with respect to the mask frame extension. 
         [0030]    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 
         [0031]    The accompanying drawings facilitate an understanding of the various embodiments of this invention. In such drawings: 
           [0032]      FIG. 1  is a perspective view of a mask including an auto-adjusting mask stabilizer according to one embodiment of the invention; 
           [0033]      FIG. 2  is a perspective view of an auto-adjusting mask stabilizer of  FIG. 1 ; 
           [0034]      FIG. 3  is a perspective view of a cushion frame of an auto-adjusting mask stabilizer of  FIG. 1 ; 
           [0035]      FIG. 4  is a perspective view of a mask extension of an auto-adjusting mask stabilizer of  FIG. 1 ; 
           [0036]      FIG. 5  is a perspective assembly view of the mask extension and cushion frame of the auto-adjusting mask stabilizer of  FIG. 1 ; 
           [0037]      FIG. 6  is a front side perspective view of the mask extension and cushion frame of the auto-adjusting mask stabilizer of  FIG. 1 ; 
           [0038]      FIG. 7  is a rear side perspective view of the mask extension and cushion frame of the auto-adjusting mask stabilizer of  FIG. 1 ; 
           [0039]      FIG. 8  is a perspective view of an auto-adjusting mask stabilizer according to another embodiment of the invention; 
           [0040]      FIG. 9  is an elevation view of an auto-adjusting mask stabilizer according to another embodiment of the invention; 
           [0041]      FIG. 10  is an elevation view of an lock release mechanism for the auto-adjusting mask stabilizer of  FIG. 9 ; 
           [0042]      FIGS. 11 and 12  are elevation views of an embodiment of a lock release mechanism for an auto-adjusting mask stabilizer according to the invention; 
           [0043]      FIG. 13  is an illustration of an auto-adjusting mask stabilizer according to another embodiment of the invention; and 
           [0044]      FIGS. 14 and 15  are sectional views of an auto-adjusting mask stabilizer according to another embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0045]    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. 
         [0046]    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. 
         [0047]    The term “air” will be taken to include breathable gases, for example air with supplemental oxygen. It is also acknowledged that the blowers described herein may be designed to pump fluids other than air. 
       First Embodiment 
       [0048]    Referring to  FIG. 1 , an auto-adjusting mask stabilizer, e.g., forehead support,  10  according to one embodiment of the invention includes a cushion frame  12  mounted to a frame extension  14 . The frame extension  14  is connected to, or formed integrally with, a mask  16  used to supply breathable gas to a patient. A separate frame extension allows the auto-adjusting mask stabilizer of the present invention to be adapted to existing mask frames. 
         [0049]    The mask  16  includes a mask frame  17  and a mask cushion  19 . The mask frame  17  includes an angled connector  18  (e.g., in the form of a swivel elbow) which has a distal end  20  for connection to a gas supply hose (not shown) and a proximal end  22  for connection to the mask  16 . The connector  18  communicates the supplied gas from the gas supply hose to the interior of the mask  16 . The mask frame  17  also includes a pair of slotted connectors  24  to which are respectively connected ends of a lower head strap (not shown) for securing the mask  16  to the patient&#39;s head. 
         [0050]    The frame extension  14  is provided on top of the mask frame  17  generally adjacent and above the patient&#39;s nose. It should be appreciated that the mask  16  shown in  FIG. 1  is just one example of a respiratory mask that may be supported by the mask stabilizer  10 . For example, the mask stabilizer  10  may also be used in supporting a nasal mask, a full-face (i.e. nose and mouth) mask, or nasal prongs, puffs, nozzles or the like. 
         [0051]    The mask stabilizer  10  may also be used with facial masks in which the angled connector  18  is incorporated into the mask in the general position of the frame extension  14 . In this type of mask, the supplied gas flows through or past the mask stabilizer  10 . 
         [0052]    The cushion frame  12  includes a pair of cushions (e.g., forehead cushions)  25  mounted at each end of the upper portion of the frame  12  on the side adapted to contact the face of the patient (e.g., the patient&#39;s forehead). Examples of cushions  25  include open or closed cell foam, silicone, dual durometer foams, single pads or multiple pads joined together. The cushions  25  may be integrally molded with the cushion frame  12  or attached thereto by clips or adhesives or the like. The cushion frame  12  also includes slotted connectors  26  adjacent each of the cushions  25  to which are respectively connected ends of an upper head strap (not shown) for securing the mask  16 , including the mask stabilizer  10 , to the patient&#39;s head. 
         [0053]    Referring to  FIGS. 2 and 4 , the frame extension  14  includes a frame extension cylinder  30 . As shown in  FIG. 4 , the frame extension cylinder  30  includes a bore  36 . A cantilevered lever  34  is formed in an outer peripheral surface of the frame extension cylinder  30 . A lock mechanism release button  32  is provided on the free end of the lever  34 . 
         [0054]    As shown in  FIGS. 2 and 4 , the cushion frame  12  includes a shaft  40  that is received in the bore  36  of the frame extension cylinder  30 . 
         [0055]    Referring to  FIG. 3 , the shaft  40  is also in the form of a cylinder. A biasing element  42 , e.g. a compression coil spring, is provided inside the shaft  40 . The biasing element  42  may be secured to the cushion frame  12  at the end of the shaft, i.e., on the portion of the cushion frame  12  that supports the cushions  25 . Referring again to  FIG. 1 , it should also be appreciated that the mask stabilizer  10  may be adjusted to control the deflection of the mask cushion  19 , for example in the region of the patient&#39;s nasal bridge. 
         [0056]    Referring to  FIG. 4 , the frame extension cylinder  30  includes radial projections  38  on the inner cylindrical surface of the cylinder  30 . The radial projections  38  extend axially along the cylinder  30 . As shown in  FIG. 5 , the radial projections  38  are received in radial grooves  44  formed in the outer circumferential surface of the shaft  40  of the cushion frame  12 . Although the frame extension cylinder  30  and the shaft  40  of the cushion frame  12  are shown having circular cross-sections, it should be appreciated that the cylinder and shaft may have a polygonal cross-section, for example. 
         [0057]    As shown in  FIG. 4 , the lock mechanism release button  32  has a pawl  50  which extends from the release button  32  radially inward of the frame extension cylinder  30 . The pawl  50  has ratchet teeth  52  provided on opposite sides. The pawl  50  and the release button  32  are resiliently supported at the end of the cantilevered lever  34 . 
         [0058]    Referring to  FIG. 5 , the shaft  40  of the cushion frame  12  includes an axial slot  45 . The slot  45  includes ratchet teeth  46  on each side. When the shaft  40  of the cushion frame  12  is inserted into the bore  36  of the frame extension cylinder  30 , the pawl  50  of the lock release button  32  is received in the axial slot  45  of the shaft  40  so that the ratchet teeth  52  of the pawl  50  engage the ratchet teeth  46  of the axial slot  45 . The engagement of the radial projections  38  of the frame extension cylinder  30  into the radial grooves  44  of the shaft  40  of the cushion frame  12  ensure that the cushion frame  12  and the frame extension cylinder  30  are properly aligned for assembly of the mask stabilizer  10 . 
         [0059]    The position shown in  FIG. 5  is the locked position of the auto-adjusting mask stabilizer  10  and relative movement between the cushion frame  12  and the mask extension  14  is prevented, or locked, by the engagement of the ratchet teeth  52  of the pawl  50  with the ratchet teeth  46  of the slot  45  or by high friction coefficient material on the pawl  50  and/or the ratchet teeth  52  to lock the movement, e.g. a clutch. 
         [0060]    The biasing element  42  operates to bias the shaft  40  of the cushion frame  12  away from the cylinder  30  of the frame extension  14 . When the lock mechanism is in the position shown in  FIG. 5 , movement of the cushion frame  12  caused by the biasing force of the biasing element  42  away from the frame extension  14  is prevented by the engagement of the ratchet teeth  52  with the ratchet teeth  46 . In order to release the lock mechanism, the release button  32  is pressed downwardly to release the engagement of the ratchet teeth  52  from the ratchet teeth  46 . When the ratchet teeth are disengaged, the biasing element  42  biases the cushion frame  12  in a direction away from the frame extension  14  toward the forehead of the patient. 
         [0061]    The engagement of the shaft  40  of the cushion frame  12  into the bore  36  of the mask extension cylinder  30  allows the cushion frame  12  to translate with respect to the mask frame  17 . Thus, the inclination between the cushion pads  25  and the patient&#39;s forehead does not change during adjustment, i.e., movement of the cushion frame  12  with respect to frame extension  14 . The mask stabilizer  10  of the present invention thus provides the ability to stabilize the vertical angle of the position of the mask  16  relative to the patient&#39;s forehead and also stabilizes the relative set position of the mask  16  throughout the patient&#39;s sleep session. 
         [0062]    Referring to  FIG. 6 , when the mask system is initially fitted, the shaft  40  of the cushion frame  12  is fully inserted into the mask extension cylinder  30 . In this position, the biasing element  42  is under compression and the forehead pads  25  are in the most outward set position so that the compression of the biasing element  42  is at a maximum and the forehead pads  25  are at their closest position to the frame extension  14 . In order to determine the ideal position of the mask  16  on the patient&#39;s face, the mask  16  is placed in contact with the patient&#39;s face and adjusted so that a good seal and comfortable fit are obtained. The lock mechanism release button  32  is then pressed down and the engagement between the ratchet teeth  52  and the ratchet teeth  46  is released. The biasing element  42  then acts to bias the cushion frame  12  toward the patient&#39;s forehead and into contact with the patient&#39;s forehead. Once the forehead pads  25  are in contact with the patient&#39;s forehead, the lock mechanism release button  32  is released and the lock mechanism returns to the locked position (i.e. the ratchet teeth  52  of the pawl  50  return to engagement with the ratchet teeth  46  of the slot  45 ). Fine tuning of the fit may be achieved by re-pressing the release button  32 , which releases the lock mechanism, and moving the mask  16  relative to the patient&#39;s face. Once the fine tuning is complete, the release button  32  is again released and the lock mechanism returns to the locked position to lock the cushion frame  12  into position. 
         [0063]    The adjustment may be performed with one hand. The patient, or clinic worker, simply presses the release button  32  and adjusts the position of the mask  16  with the same hand used to depress the release button  32 . This allows adjustment of the fit of the mask  16  according to the present invention in a quicker manner than mask systems of the prior art. A mask system including the auto-adjusting stabilizer according to the invention may be initially fit in under one second, almost instantaneously, as opposed to up to five seconds as may be required for forehead supports according to the prior art. As the mask adjustment may be performed with one hand, the mask system of the present invention requires less dexterity to adjust than masks of the prior art. 
         [0064]    As shown in  FIG. 3 , the biasing element  42  may be a coiled compression spring. For example, the spring could be a stainless steel or nickel-plated spring. It should be appreciated, however, that the biasing element  42  may take other forms. For example, the biasing element  42  may be a compressible open cell foam or silicone rubber elastic band. As another example shown in  FIG. 13 , the biasing element  42  may be an air spring having a reservoir, or an air bladder or integrally spring-loaded bellows  42   a  with an elastic memory so as the air is compressed the bladder can stretch and provide a spring force. The air bladder could be in communication with the air being delivered to the mask so that an air line  60  is provided between the inside of the mask frame and the air bladder or bellows  42   a  so that the air bladder or bellows  42   a  is under the influence of air pressure which influences or biases the movement of the cushion frame  12  toward the patient&#39;s face. It should also be appreciated that the air bladder may be provided with a valve  62  allowing the deflation of the air bladder. In operation, the air bladder or bellows  42   a  is normally in an extended position. Prior to fitting the mask to the patient, the valve  60  is opened and the air bladder or bellows  42  as is compressed during fitting. The valve  60  is then closed to fix the support in position. 
       Second Embodiment 
       [0065]    Referring to  FIG. 8 , according to another embodiment of the invention, a bushing  61  may be provided between the release button  32  and the outer surface of the mask extension cylinder  30 . The bushing  61  serves to adjust the force required to depress the release button  32 . The bushing  61  may also serve to prevent accidental release of the locking mechanism, for example during movement of the patient during the sleep session. The bushing  61  may also bias the locking mechanism into the locked position. 
       Alternate Embodiments 
       [0066]    Although the lock mechanism release button  32  is shown in the attached drawings as being provided on top of the mask frame extension cylinder  30 , it should be appreciated that the release button could also be provided anywhere along the circumference of the mask frame extension cylinder  30 , with a corresponding movement of the slot  45  and ratchet teeth  46  of the shaft  40  of the cushion frame  12 . It should also be appreciated that the release button could be provided at the closed end of the mask frame extension cylinder  30 . However, positioning the release button  32  on top of the frame extension cylinder  30  allows the patient to activate the release button in a natural way and the force that is required to activate the release button is in a plane normal to the direction along which the patient or fitter is positioning the mask. This minimizes the chance of moving the mask while adjusting the position of the cushion frame  12 . 
         [0067]    Spacing of the ratchet teeth  46  in the slot  45  of the shaft  40  of the cushion frame  12  may be, for example, 1 mm. The position of the cushion frame  12  may thus be adjusted in 1 mm increments. It should be appreciated, however, that other spacings of the ratchet teeth  46  are within the spirit and scope of the invention. 
       Third Embodiment 
       [0068]    Referring to  FIG. 9 , an auto-adjusting stabilizer according to another embodiment of the invention includes a frame extension  14   a  having a frame extension cylinder  30   a . A shaft  40   a  of a cushion frame (not shown) is received in the frame extension cylinder  30   a . A biasing element (not shown) is provided between the cylinder  30   a  and the shaft  40   a  to bias the shaft  40   a  relative to the frame  30   a.    
         [0069]    Radial projections  38   a  of the frame extension cylinder  30   a  frictionally engage the outer surface of the shaft  40   a  to retain the shaft  40   a  against movement relative to the cylinder  30   a  caused by the biasing element. A lock mechanism release button  32   a  is provided for releasing the engagement of the radial projections  38   a  from the shaft  40   a  to permit relative movement between the shaft  40   a  and the cylinder  30   a  by the biasing element. Depressing the release button  32   a  causes the cylinder  30   a  to deform, thus disengaging the projections  38   a  from the cylinder  40   a.    
       Fourth Embodiment 
       [0070]    As shown in  FIG. 10 , a lock mechanism  32   j  according to an embodiment of the invention includes a lock mechanism release button  32   b  engagable by the patient or clinician. The release button  32   b  is supported by a release button support  32   c . The release button support  32   c  includes a cylindrical portion  32   d  that receives a release mechanism sleeve  32   e . The sleeve  32   e  is concentrically supported by the cylindrical portion  32   d  to permit relative movement between the release button support  32   c  and the sleeve  32   e . Resilient, curved legs  32   f  couple the support  32   c  to the sleeve  32   e  and a cylindrical plug  32   g  connected to the release button  32   b  couples the release button  32   b  to the support  32   c . A biasing element  32   k , e.g., a spring, is provided between the cylindrical plug  32   g  and a cross element  32   i  in the sleeve  32   e  to bias the lock mechanism  32  into the position shown in  FIG. 10 . Depressing the release button  32   b  causes the plug  32   g  to compress the biasing element  32   k . The biasing element  32   k  is initially compressed by movement of the release button  32   b , and then transfers further depression of the release button  32   b  to the sleeve  32   e  through engagement of the biasing element and the cross element  32   i.    
       Fifth Embodiment 
       [0071]    The ratchet teeth of the lock mechanism shown in  FIGS. 1-7  may be replaced by a friction lock. Referring to  FIGS. 11 and 12 , the release button  32   b  of the lock release mechanism includes a pawl  50   b . The pawl  50   b  includes an engagement surface  53  on each side that engages a corresponding engagement surface  47  of the slot  45   b  of the shaft  40   b  of the cushion frame to lock the cushion frame in position. The engagement surfaces  53  of the pawl  50   b  and the engagement surfaces  47  of the slot  45   b  may be textured, such as by knurling, to increase the friction between the pawl  50   b  and the sides of the slot  45   b . The use of a friction lock would provide for continuous, or infinite, variability of the position of the cushion frame  12  with respect to the mask  16 . In contrast to prior art forehead supports which provide a large number of discrete set points for the support and which may be complicated to use and fit, the provision of an infinite number of set points simplifies using and fitting masks incorporating an auto-adjusting stabilizer according to the invention. Although  FIGS. 11 and 12  include a space between the engagement surfaces  47  and  53  for illustrative purposes, it should be appreciated that the surfaces are in contact. 
         [0072]    The release button  32   b  is biased into the locked position shown in  FIGS. 11 and 12  by a biasing element  32   k , e.g., a spring. A projecting rim  41   b  in the slot  45   b  of the shaft  40   b  engages a shoulder  33   b  of the release button  32   b  to maintain the release button  32   b  in the locked position shown in  FIG. 11  When the release button  32   b  is depressed, as shown in  FIG. 12 , the amount of engagement between the engagement surfaces  47  and  53  is reduced and the amount of friction is correspondingly reduced. The shaft  40   b  of the cushion frame is then movable relative to the mask extension cylinder that supports the release button  32   b  to permit adjustment of the position of the cushion frame. 
       Sixth Embodiment 
       [0073]    Referring to  FIGS. 14 and 15 , according to another embodiment, the cushion frame  12  may include a flexible member  72  which has two side by side spaced apart tongues  74  and a middle protruding button  76  on its distal end. The frame extension  14  may include two generally arcuate shaped portions  78  that each have a pair of four grooves  80 . It should be appreciated that the pair of four grooves is merely an example and that only two or more grooves are required. It should also be appreciated that the flexible member  72  can be on the frame extension  14  and the grooves  40  can be on the cushion frame  12 . The tongue  74  and the grooves  80  extend in a direction substantially parallel to a line extending radially from the axis  70 . The cushion frame  12  may be constructed from a plastic material, such as polypropylene or polycarbonate, which allows the member  72  to be flexed relative to the cushion frame  12  upon which is mounted when pressure is applied to the button  76  in the direction of arrow  82 . The corresponding movement of the tongues  74  releases them from engagement with one of the pairs of grooves  80  (as shown in  FIG. 15 ) to allow angular adjustment between the cushion frame  12  and the joining member  14  about the axis  30 . Releasing the button  76  allows the tongue  74  to resiliently flex back towards the grooves  80 . When the tongues  74  and one of the pairs of grooves  80  are aligned (as shown in  FIG. 14 ) the tongues  74  engage one of the pair of grooves  80 . When the tongues  74  are engaged with one of the pair of grooves, the cushion frame  12  and joining member  14  are locked against pivotal movement therebetween at a predetermined angle. 
         [0074]    A biasing member, such as a torsion spring (not shown), may be provided between the cushion frame  12  and the mask extension  14  to bias the cushion frame  12  into a position when the button  76  is released. For example, the biasing member may be configured to bias the cushion frame  12  toward the face of the patient when the button  76  is pressed. Alternatively, the biasing member may be configured to bias the cushion frame  12  away from the face of the patient when the button  76  is pressed. 
         [0075]    The cushions  25  may be supported on the cushion frame  12  by a resilient member  90 . For example, the resilient member  90  may be a silicone rubber stem-like member. As the cushion frame  12  rotates about the axis  70 , the resilient member  90  is able to flex or bend to maintain the contact face of the cushion  25  flush against the face of the patient, e.g. against the patient&#39;s forehead. 
         [0076]    It should be appreciated that the auto-adjusting mask stabilizer may be incorporated into any mask system where the fitting and correct adjustment of the mask relative to the wearer&#39;s head or face can be achieved. For example, the auto-adjusting mask stabilizer of the invention may be used in mask systems that are not provided with a forehead support, but instead utilize, for example, a cheek support or upper lip support. It should further be appreciated that the auto-adjusting mask stabilizer of the invention may be utilized in a mask system in which the forehead support is located or otherwise attached to a headgear system. It should be even further appreciated that the auto-adjusting mask stabilizer may not include a lock mechanism. In such case, the cushion frame would be biased against the patient&#39;s head, e.g., forehead, by the biasing element and its position would self-adjust to the patient. 
         [0077]    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. Furthermore, each individual component of any given assembly, one or more portions of an individual component of any given assembly, and various combinations of components from one or more embodiments may include one or more ornamental design features. 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, barriatric 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.