Abstract:
A forehead support ( 10 ) is disclosed that is adapted to be secured to a respiratory mask ( 16 ). The forehead support ( 10 ) including a joining member ( 14 ) for securing to the mask ( 16 ) and a cushion frame ( 12 ) pivotally mounted to the joining member ( 14 ). The cushion frame ( 12 ) is adapted to locate one or more forehead cushions ( 25 ). The cushion frame ( 12 ) is also adapted to pivot relative to the joining member ( 14 ). The cushion frame ( 12 ) is also selectively lockable at two or more predetermined angular positions relative to the joining member ( 14 ).  
     A respiratory mask assembly comprising a respiratory mask ( 16 ) and a forehead support ( 10 ) adapted to be secured to the mask ( 16 ) is also disclosed.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation of U.S. application Ser. No. 10/700,252, filed Nov. 4, 2003, now allowed, which is a continuation of U.S. application Ser. No. 10/264,326, filed Oct. 4, 2002, now U.S. Pat. No. 6,860,269, which is a which is a continuation of U.S. application Ser. No. 09/502,745, filed Feb. 11, 2000, now U.S. Pat. No. 6,532,961, which claims the benefit of Australian Patent Application No. PQ 1040, filed Jun. 18, 1999, each incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates to a forehead support for a facial mask used to supply breathable gas to a wearers 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 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 invention is not limited to these particular uses and is also suitable for use with, for example, full-face (ie. nose and mouth) masks.  
       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 pressurised 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 0.  
         [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, as disclosed in the applicant&#39;s international PCT patent application No. PCT/AU97/00631.  
         [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, unless otherwise specifically indicated.  
         [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 includes a cushion positioned against the wearer&#39;s face and is normally secured to the wearer&#39;s head by straps. The straps are adjusted to pull the mask against the face to achieve a gas tight seal between the cushion and the wearer&#39;s face.  
         [0012]     A problem that arises with existing masks is that with the use of straps, the mask is compressed against the wearer&#39;s face and may push unduly hard on the wearer&#39;s nose. Additionally, the mask may move around the wearer&#39;s face. Thus, there has been hitherto provided 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 as well as minimising 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]     Forehead supports with a single cushion and a single contact point on the forehead are known.  
         [0014]     The applicant&#39;s U.S. patent application Ser. No. 09/008,708 relates to a substantially rigid one-piece forehead support having a pair of forehead cushions mounted at each outer end of the support. This forehead support is connected to the top of a facial mask and includes an adjustment mechanism to allow the spacing between the top of the facial mask and the forehead support to be altered between predetermined positions to alter the angle of the mask relative to the wearer&#39;s head to suit the wearer&#39;s facial topography.  
         [0015]     The applicant&#39;s Australian provisional patent application No. PP9499 relates to a forehead support having a pair of pivotable arms that each have a forehead cushion mounted at their distal end. This forehead support is connected to the top of a mask and includes an adjustable mechanism to allow the angle between the arms to be altered between predetermined positions to alter the angle of the mask relative to the wearer&#39;s head to suit the wearer&#39;s facial topography.  
         [0016]     It is an object of the present invention to provide an alternate form of forehead support.  
       SUMMARY OF THE INVENTION  
       [0017]     Accordingly, in a first aspect, the present invention provides a forehead support adapted to be secured to a respiratory mask, said forehead support including a joining member for securing to the mask and a cushion frame pivotally mounted to the joining member, wherein: the cushion frame is adapted to locate one or more forehead cushions; the cushion frame is adapted to pivot relative to the joining member; and the cushion frame is selectively lockable at two or more predetermined angular positions relative to the joining member.  
         [0018]     In a second aspect, the present invention provides a respiratory mask assembly comprising a respiratory mask and a forehead support adapted to be secured to the mask, said forehead support including a joining member for securing to the mask and a cushion frame pivotally mounted to the joining member, wherein: the cushion frame is adapted to locate one or more forehead cushions; the cushion frame is adapted to pivot relative to the joining member; and the cushion frame is selectively lockable at two or more predetermined angular positions relative to the joining member.  
         [0019]     The cushion frame is preferably T-shaped and includes a forehead cushion at each end of the upper portion of the T.  
         [0020]     Preferably, one of the cushion frame or joining member includes a tongue adapted to be received in one of at least two grooves provided on the other of the cushion frame or joining member so as to lock the cushion frame and joining member at one of the two or more predetermined angular positions.  
         [0021]     More preferably, a pair of the tongues are provided on the cushion frame and at least two pairs of grooves are provided on the joining member.  
         [0022]     The tongue(s) is/are preferably provided on a semi-rigid member which is adapted to permit the tongue(s) to be moved out of engagement with the grooves by manual manipulation of the member. The tongue(s) is/are preferably connected to a button adapted to protrude from the cushion frame to facilitate manual manipulation of the member.  
         [0023]     The cushion frame preferably includes means to connect a head strap thereto.  
         [0024]     The mask preferably also include means to connect a head strap thereto.  
         [0025]     The joining member can be produced from, for example, polypropylene or polycarbonate.  
         [0026]     The mask can include a mask shell and a mask cushion. The mask shell can be produced from, for example, polypropylene or polycarbonate.  
         [0027]     The cushion frame can be produced from, for example, polypropylene or polycarbonate. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0028]     Preferred embodiments of the invention will now be described, by way of examples only, with reference to the accompanying drawings in which:  
         [0029]      FIG. 1  is a front perspective view of a first embodiment of a forehead support according to the invention connected to a nasal mask;  
         [0030]      FIG. 2  is a cross sectional side view of the forehead support shown in  FIG. 1  with the tongue of the cushion frame engaged with one of the pairs of grooves of the joining member;  
         [0031]      FIG. 3  is a cross sectional side view of the forehead support shown in  FIG. 1  with the tongue of the cushion frame free of engagement with the pairs of grooves of the joining member;  
         [0032]      FIG. 4  is a cross sectional side view of the forehead support shown in  FIG. 1  adjacent a wearer&#39;s head with the tongues and grooves engaged at the first of four positions;  
         [0033]      FIG. 5  is a cross sectional side view of the forehead support shown in  FIG. 1  adjacent a wearer&#39;s head with the tongues and grooves engaged in the second of four positions;  
         [0034]      FIG. 6  is a cross sectional side view of the forehead support shown in  FIG. 1  adjacent a wearer&#39;s head with the tongues and grooves engaged at the third of four positions;  
         [0035]      FIG. 7  is a cross sectional side view of the forehead support shown in  FIG. 1  adjacent a wearer&#39;s head with the tongues and grooves engaged at the fourth of four positions;  
         [0036]      FIG. 8  is a partial exploded perspective view of a second embodiment of a forehead support according to the invention.  
         [0037]      FIG. 9  is a cross sectional side view of a third embodiment of a forehead support according to the invention that includes an integrally formed cushion frame and joining member;  
         [0038]      FIG. 10  is a cross sectional view of the forehead support shown in  FIG. 9  with the tongue and grooves engaged at the first of four positions.  
         [0039]      FIG. 11  is a cross sectional view of the forehead support shown in  FIG. 9  with the tongue and grooves engaged at the second of four positions.  
         [0040]      FIG. 12  is a cross sectional view of the forehead support shown in  FIG. 9  with the tongue and grooves engaged at the third of four positions.  
         [0041]      FIG. 13  is a cross sectional view of the forehead support shown in  FIG. 9  with the tongue and grooves engaged at the fourth of four positions;  
         [0042]      FIG. 14  is a cross sectional view of the forehead support shown in  FIG. 9  with the tongue free of engagement with the grooves; and  
         [0043]      FIG. 15  is a side view, with enlarged details (in  FIG. 16 ), of a fourth embodiment of a forehead support according to the invention. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0044]      FIG. 1  shows a first embodiment of a forehead support  10  according to the present invention. The forehead support  10  includes a generally T-shaped cushion frame  12  pivotally mounted to a joining member  14 . The joining member  14  is connected to a nasal respiratory mask  16  used to supply breathable gas to a wearer&#39;s airways.  
         [0045]     The mask  16  includes a mask shell  17  and a mask cushion  19 . The mask shell  17  also includes an angled connector  18  which has a distal end  20  for connection to a gas supply conduit (not shown) and a proximal end  22  for connection to the mask  16 . The connector  18  communicates the supplied gas from the gas supply conduit to the interior of the mask  16 . The mask shell  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 nasal mask to the wearer&#39;s head.  
         [0046]     The joining member  14  is connected on top of the mask shell  17  generally adjacent and above the wearer&#39;s nose. It will be appreciated that the nasal mask  16  shown is just one example of a respiratory mask that could be supported by the forehead support  10 . For example, the forehead support also finds application in supporting full-face (ie. nose and mouth) masks.  
         [0047]     Forehead supports according to the invention can also be used with facial masks in which the gas supply connector  18  is incorporated into the mask in the general position of the joining member  14 . In this type of mask, the supplied gas flows through or past the forehead support  10 .  
         [0048]     The T-shaped cushion frame  12  includes a pair of forehead cushions  25  mounted at each end of the upper portion of the T on the wearer contacting side. Examples of cushions  25  include open or closed cell foam, silicone, dual durometer foams, single pads or multiple pads joined together. The forehead cushions  25  can be integrally moulded with the frame  12  or attached thereto by clips or adhesives or the like. The frame  12  also includes a slotted connector  26  adjacent each of the forehead cushions  25  to which are respectively connected ends of an upper head strap (not shown) for securing the cushion frame  12  to the wearer&#39;s head.  
         [0049]     The T-shaped cushion frame  12  also includes a pair of shafts  27  (only one shown) on the lower portion of the T which are each respectively received in part circular openings  28  (only one shown) provided on the joining member  14 . The shafts  27  can pivot or rotate in their respective openings  28  to provide for pivotal or rotational movement between the cushion frame  12  and the joining member  14  about axis  30  in the direction of double-headed arrow  31 .  
         [0050]     The curved shape of the cushions  25  allows them to effectively “roll” over the wearer&#39;s forehead during angular adjustment between the cushion frame  12  and the joining member  14 .  
         [0051]     As best shown in  FIGS. 2 and 3 , the cushion frame  12  also includes a flexible member  32  which has two side by side spaced apart tongues  34  and a middle protruding button  36  on its distal end. The joining member  14  also includes two generally arcuate shaped portions  38  that each have a pair of four grooves  40 . It will be appreciated that the pair of four grooves is merely preferable and that only two or more grooves are required. It will also be appreciated that the flexible member  32  can be on the joining member  14  and the grooves  40  can be on the cushion frame  12 . The tongue  34  and the grooves  40  extend in a direction substantially parallel to a line extending radially from the axis  30 .  
         [0052]     The cushion frame  12  is constructed from a plastics material, such as polypropylene or polycarbonate, which allows the member  32  to be flexed relative to the cushion frame  12  upon which is mounted when pressure is applied to the button  36  in the direction of arrow  42 . The corresponding movement of the tongues  34  releases them from engagement with one of the pairs of grooves  40  (as shown in  FIG. 3 ) to allow angular adjustment between the cushion frame  12  and the joining member  14  about the axis  30 . Releasing the button  36  allows the tongue  34  to resiliently flex back towards the grooves  40 . When the tongues  34  and one of the pairs of grooves  40  are aligned (as shown in  FIGS. 2 and 4  to  7 ) the tongues  34  engage one of the pair of grooves  40 . When the tongues  34  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.  
         [0053]     FIGS.  4  to  7  respectively show forehead support  10  adjacent the heads of different wearers with the tongues  34  engaged in the first, second, third and fourth of the four pairs of grooves  40 .  
         [0054]     As FIGS.  4  to  7  show, the angle between the cushion frame  12  and the joining member  14  adjacent the wearer&#39;s forehead can be increased to suit wearer&#39;s with relatively high nasal regions and relatively low foreheads ( FIGS. 4 and 5 ) and decreased to suit wearers with relatively low nasal regions and relatively high foreheads ( FIGS. 6 and 7 ).  
         [0055]     In this way the forehead support  10  advantageously allows the mask  16  to be positioned to comfortably suit the particular topography of the wearer&#39;s face to ensure the mask cushion  19  is positioned ideally relative to the wearer&#39;s face. As examples, the relative position of the cushion frame  12  and the joining member  14  in  FIG. 4  would be more suitable for use with a wearer having a shallow forehead or protruding cheeks or nose whilst the position of the cushion frame and joining member  14  in  FIG. 7  would be more suitable for use with a wearers having a protruding or bulbous forehead.  
         [0056]      FIG. 8  shows a second embodiment of a forehead support  50  according to the present invention. Like reference numerals to those used in describing the first embodiment will be used to denote like features in relation to the second embodiment.  
         [0057]     In the second embodiment, their are two buttons  36 . Pressing the buttons together in the direction of arrows  52  flexes the tongues  34  towards each other to disengage them from the grooves  40  and allow angular adjustment between the cushion frame  12  and the joining member  14 . Releasing the buttons  36  allows the tongues  34  to resiliently flex towards, and into engagement with, the grooves  40  to lock the cushion frame  12  and the joining member  14  against relative pivotal movement.  
         [0058]     FIGS.  9  to  14  show a third embodiment of a forehead support  60  according to the present invention. Like reference to those used in describing the first embodiment will also be used to denote like features in relation to the third embodiment.  
         [0059]     In the third embodiment, the cushion frame  12  is integrally moulded with the joining member  14  and joined by an integral hinge  62  (sometimes known as a natural or living hinge). The cushion frame  12  and the joining member  14  can be pivotted relative to each other about the hinge  62 . The forehead support  60  is moulded in a substantially ‘flat’ configuration, as shown in  FIG. 9 . The cushion frame  12  is then pivotted through approximately 180° relative to the joining member  14  until the tongue  34  engages one of the four grooves  40 . As with the earlier embodiments, pressing the button  36  in the direction of arrow  42  frees the tongue  34  from engagement with the grooves to allow adjustment of the angle between the cushion frame  12  and the joining member  14 . The button  36  and the tongue  34  are inherently biased to a position engaging one of the grooves  40 , again consistent with earlier embodiments.  
         [0060]     In the preferred form shown, the mask shell  17  is also integrally formed with the joining member  14 . This simplifies manufacturing and assembly and reduces production costs. The forehead support  60  is preferably manufactured from polypropylene due to its ability to mould integral hinges.  
         [0061]      FIGS. 15 and 16  show a fourth embodiment of a forehead support  100  according to the invention. Like reference to those used in describing the first embodiment will also be used to denote like features in relation to the fourth embodiment.  
         [0062]     The fourth embodiment is almost identical to the first embodiment except the tongue  34  and the grooves  40  are angled with respect to a line extending radially from the axis  30  to the tongue  34  or the grooves  40 . This angled arrangement reduces the likelihood that the tongue  34  will inadvertently release from engagement with one of the grooves  40  if the front of the mask  16  is subjected to a force in the direction of the wearer&#39;s face.  
         [0063]     Although the invention has been described with reference to a specific example, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.  
         [0064]     As an example, the forehead support can include means to resiliently bias the cushion frame and the joining member relative to one another such that they increase or decrease their angle relative to one another when the tongues are disengaged from one of the pairs of slots.