Patent Abstract:
A patient interface that is comfortable for a user to wear is disclosed. The patient interface includes a forehead rest and cushion. In particular the cushion includes a deformable resilient member that when compressed creates a uniformly and gradually increasing force while evenly distributing the pressure on the forehead of the patient.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation application of U.S. patent application Ser. No. 13/360,227, filed Jan. 27, 2012, which is a divisional application of U.S. patent application Ser. No. 12/784,016, filed May 20, 2010 (issued on Feb. 28, 2012 as U.S. Pat. No. 8,122,887), which is a divisional application of U.S. patent application Ser. No. 10/564,998 (issued on Jun. 15, 2010 as U.S. Pat. No. 7,735,487), which received a 371 filing date of Jun. 6, 2006 and is a 371 filing of PCT/NZ2004/000165, filed on Jul. 27, 2004. These applications claim priority from New Zealand Application No. 527313, which was filed on Jul. 30, 2003. All of these references are hereby incorporated by reference in their entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates to patient interfaces particularly though not solely for use in delivering Continuous Positive Airways Pressure (CPAP) therapy to patients suffering from obstructive sleep apnoea (OSA). In particular the present invention relates to forehead rest pads on patient interfaces. 
         [0004]    2. Description of the Related Art 
         [0005]    In the art of respiration devices, there are well known variety of respiratory masks which cover the nose and/or mouth of a human user in order to provide a continuous seal around the nasal and/or oral areas of the face such that gas may be provided at positive pressure within the mask for consumption by the user. The uses for such masks range from high altitude breathing (i.e., aviation applications) to mining and fire fighting applications, to various medical diagnostic and therapeutic applications. 
         [0006]    One requisite of such respiratory masks has been that they provide an effective seal against the user&#39;s face to prevent leakage of the gas being supplied. Commonly, in prior mask configurations, a good mask-to-face seal has been attained in many instances only with considerable discomfort for the user. This problem is most crucial in those applications, especially medical applications, which require the user to wear such a mask continuously for hours or perhaps even days. In such situations, the user will not tolerate the mask for long durations and optimum therapeutic or diagnostic objectives thus will not be achieved, or will be achieved with great difficulty and considerable user discomfort. 
         [0007]    U.S. Pat. No. 5,243,971 and U.S. Pat. No. 6,112,746 are examples of prior art attempts to improve the mask system. U.S. Pat. No. 5,570,689 and PCT publication No. WO 00/78384, and U.S. Pat. No. 6,119,693 are examples of attempts to improve the forehead rest. 
       SUMMARY OF THE INVENTION 
       [0008]    It is an object of the present invention to attempt to provide a patient interface which goes some way to overcoming the abovementioned disadvantages in the prior art or which will at least provide the industry with a useful choice. 
         [0009]    Accordingly in a first aspect the present invention consists in a device for delivering a supply of gases to a user comprising: 
         [0010]    a patient interface, in use in fluid communication with said supply of gases, 
         [0011]    a forehead rest engaging said interface including a deformable resilient member configured to in use rest against the face of a patient, said deformable resilient member when compressed in use creating a uniformly and gradually increasing force, while evenly distributing the pressure on the area of the forehead of said patient that contacts said resilient member. 
         [0012]    Preferably said deformable resilient member has a top surface and a base connected by two side walls, said side walls being thin and in use are compressible. 
         [0013]    Preferably said top surface is substantially thicker than said side walls. 
         [0014]    Preferably said top surface includes additional support at its centre to limit its collapse. 
         [0015]    Preferably said side walls are capable of folding under compression. 
         [0016]    Preferably said deformable resilient member is moulded from silicone. 
         [0017]    Alternatively said deformable resilient member is extruded from silicone. 
         [0018]    In a second aspect the present invention consists in a device for delivering a supply of gases to a user comprising: 
         [0019]    a patient interface, in use in fluid communication with said supply of gases, 
         [0020]    a forehead rest engaging said interface including a deformable resilient member configured to in use rest against the face of a patient, said deformable resilient member being of a hollow conical shape where in use and under compression the top part of said hollow cone deforms or the side walls of said cone deform. 
         [0021]    Preferably said deformable resilient member is moulded from silicone. 
         [0022]    Alternatively said deformable resilient member is extruded from silicone. 
         [0023]    In a third aspect the present invention consists in a device for delivering a supply of gases to a user comprising: 
         [0024]    a patient interface, in use in fluid communication with said supply of gases, 
         [0025]    a forehead rest engaging said interface, an adjustable deformable resilient member mounted on said forehead rest, said adjustable deformable resilient member configured to in use rest against the face of a patient, said resilient member is height adjustable such that said patient can adjust the distance between said forehead rest and the face of said patient. 
         [0026]    Preferably said adjustable deformable resilient member is at least one adjustable strap attached and adjustable on said forehead rest. 
         [0027]    Alternatively said adjustable deformable resilient member is a member rotatably mounted on said forehead rest. 
         [0028]    In the alternate form the adjustable deformable resilient member being rotatable relative to said forehead rest 
         [0029]    In a further form said resilient member has two ends, one of the resilient member being fixed to the forehead rest, the other end of the strap is free, said free end capable of sliding relative to said forehead rest, said sliding of free end of strap allowing said user to adjust the height between said forehead rest and said forehead of said user. 
         [0030]    Preferably said forehead rest includes a plurality of recesses, the free end of the strap including a slideable sleeve, said slideable sleeve sliding relative to said forehead rest and slideably moving said strap to adjust the height of said resilient member, said sleeve also capable of being fixed into any one of the recesses, said recesses allowing varying degrees of height adjustment. 
         [0031]    Preferably said forehead rest also including an aperture, said fixed end of strap fixed to said forehead rest by engaging into said aperture. 
         [0032]    Preferably said strap includes a plurality of protrusions at each end, said protrusions at said fixed end of said strap engaging with said aperture to fix said strap to said forehead rest, said protrusions at said free end of said strap engaging with said sleeve to connect said strap to said sliding sleeve. 
         [0033]    Preferably said forehead rest is substantially T shaped, said forehead rest comprising two lateral arms extending outward from a vertical arm, said resilient member attached to at least one lateral arm of said forehead rest. 
         [0034]    Alternatively said forehead rest is substantially I shaped. 
         [0035]    In a further form said strap has a fixed end and a movable end, said fixed end fixed to the forehead rest, said movable end is arranged on said forehead rest to form a substantially circular shape that provides a cushioning effect should a force be applied. 
         [0036]    Preferably said movable end of said strap being threaded through an aperture in the arm to form said circular shape, said movable end of said strap being adjustable on said forehead rest to allow a user to adjust the size of the circular shape created by said strap. 
         [0037]    Preferably said strap includes a plurality of spaced apart apertures on the strap, said forehead rest including a protrusion extending outward from said forehead rest, said protrusion capable of engaging with any one of said apertures on said strap to fix the movable end of said strap and fix the size of said circular shape, said plurality of spaced apart holes on strap allowing a user to adjust the size of said circular shape. 
         [0038]    Preferably said forehead rest includes a holding sleeve, said holding sleeve holding said strap in a substantially correct orientation relative to the forehead rest and protrusion on said forehead rest. 
         [0039]    Preferably said forehead rest is a substantially I shaped piece. 
         [0040]    In another form said strap is arranged on said forehead rest to form two arced sections relative to said forehead rest, said arced sections resting against a user&#39;s head and providing a cushioning effect. 
         [0041]    Preferably said forehead rest includes at least one aperture, said strap curled through said aperture to form a middle section extending in the opposing direction to said arced sections. 
         [0042]    Preferably said strap is folded back on itself to form said middle section, said strap having two ends, both ends of said strap fixed to opposing ends of said forehead rest. 
         [0043]    Preferably said forehead rest includes a lip at each end of said forehead rest, said rest comprising an abutment at each end of said strap, said abutment engaging with said lip to fix each end of said strap to said forehead rest. 
         [0044]    Preferably said forehead rest includes a pair of apertures said strap curling through both said apertures to form said middle section and arced sections. 
         [0045]    Preferably said middle section can be pulled through or pushed through said aperture or apertures in order to increase or decrease the size of said arced sections. 
         [0046]    Preferably said strap includes a plurality of spaced apart notches along the edge of said strap, said notches capable of engaging with said aperture or apertures to hold said middle section in place, said notches providing incremental positions for the middle section to be held and said notches providing incremental sizes of said arced sections. 
         [0047]    Preferably said strap has notches along both edges of said strap to provide for better grip and engagement with said aperture or apertures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0048]    One preferred form of the present invention will now be described with reference to the accompanying drawings, 
           [0049]      FIG. 1  is a block diagram of a humidified continuous positive airway pressure (system) as might be used in conjunction with the present invention, 
           [0050]      FIG. 2  is an illustration of the nasal mask in use according to the preferred embodiment of the present invention, 
           [0051]      FIG. 3  shows a perspective view of the mask with cushion, 
           [0052]      FIG. 4  is a cutaway view of the mask showing the cushion, 
           [0053]      FIG. 5  is a cutaway view of the periphery of the outer membrane, 
           [0054]      FIG. 6  is a cutaway view of the periphery of the mask body portion, 
           [0055]      FIG. 7  shows a prior art forehead rest in isolation, 
           [0056]      FIG. 8  shows a section view of the prior art forehead rest of  FIG. 7 , 
           [0057]      FIG. 9  shows a perspective view of the forehead rest cushion of  FIG. 7 , 
           [0058]      FIG. 10  is a section of a further prior art forehead rest cushion, 
           [0059]      FIG. 11  is a section of perspective view of the forehead rest cushion of  FIG. 10 , 
           [0060]      FIG. 12  is a back view showing the slots in the forehead rest for each cushion to lock into, 
           [0061]      FIG. 13  is a perspective view of a first embodiment of a forehead rest cushion of the present invention, 
           [0062]      FIG. 14  is a perspective view of a second embodiment of a forehead rest cushion of the present invention, 
           [0063]      FIG. 15  is an alternative perspective view of the forehead rest cushion of  FIG. 14 , 
           [0064]      FIG. 16  is a section of the forehead rest cushion of  FIG. 14 , 
           [0065]      FIG. 17  is a side view of a third embodiment of a forehead rest cushion of the present invention, 
           [0066]      FIG. 18  is an alternative perspective view of the forehead rest cushion of  FIG. 17 , 
           [0067]      FIG. 19  is a section view of the forehead rest cushion of  FIG. 17 , 
           [0068]      FIG. 20  is a perspective view of a fourth embodiment of a forehead rest cushion of the present invention, 
           [0069]      FIG. 21  is a section of the forehead rest cushion of  FIG. 20 , 
           [0070]      FIG. 22  is a perspective view of a fifth embodiment of a forehead rest cushion of the present invention, 
           [0071]      FIG. 23  is a sixth embodiment of a forehead rest cushion of the present invention, 
           [0072]      FIG. 24  is a seventh embodiment of a forehead rest cushion of the present invention, 
           [0073]      FIG. 25  is a perspective view of an eighth embodiment of a forehead rest cushion of the present invention, 
           [0074]      FIG. 26  is a perspective view of a ninth embodiment of a forehead rest cushion of the present invention, 
           [0075]      FIG. 27  is a perspective view of a tenth embodiment of a forehead rest cushion of the present invention, where the forehead rest cushion is adjustable to a user&#39;s requirements, 
           [0076]      FIG. 28  is a perspective view of an eleventh embodiment of a forehead rest cushion of the present invention, this embodiment also being incapable of being adjusted by the user, 
           [0077]      FIG. 29  is a perspective view of a twelfth embodiment of the forehead rest cushion of the present invention, where the forehead rest cushion is adjustable, 
           [0078]      FIG. 30  is a perspective view of a thirteenth embodiment of a forehead rest cushion of the present invention, this embodiment also being adjustable, 
           [0079]      FIG. 31  is a perspective view of a fourteenth embodiment of a forehead rest cushion of the present invention, 
           [0080]      FIG. 32  is a perspective view of a fifteenth embodiment of a forehead rest cushion of the present invention, and 
           [0081]      FIG. 33  is a perspective view of a sixteenth embodiment of a forehead rest cushion of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0082]    The present invention provides improvements in the delivery of humidified gases therapy. In particular a patient interface is described which is more comfortable for the user to wear and reduces leakage as compared with the prior art. It will be appreciated that the patient interface as described in the preferred embodiment of the present invention can be used in respiratory care generally or with a ventilator but will now be described below with reference to use in a humidified CPAP system. It will also be appreciated that the present invention can be applied to any form of patient interface including, but not limited to, nasal masks, oral masks and mouthpieces. 
         [0083]    With reference to  FIG. 1  a humidified Continuous Positive Airway Pressure (CPAP) system is shown in which a patient  1  is receiving humidified and pressurised gases through a patient interface  2  connected to a humidified gases transportation pathway or inspiratory conduit  3 . It should be understood that delivery systems could also be VPAP (Variable Positive Airway Pressure) and BiPAP (Bi-level Positive Airway Pressure) or numerous other forms of respiratory therapy. Inspiratory conduit  3  is connected to the outlet  4  of a humidification chamber  5  which contains a volume of water  6 . Inspiratory conduit  3  may contain heating means or heater wires (not shown) which heat the walls of the conduit to reduce condensation of humidified gases within the conduit. Humidification chamber  6  is preferably formed from a plastics material and may have a highly heat conductive base (for example an aluminium base) which is in direct contact with a heater plate  7  of humidifier  8 . Humidifier  8  is provided with control means or electronic controller  9  which may comprise a microprocessor based controller executing computer software commands stored in associated memory. 
         [0084]    Controller  9  receives input from sources such as user input means or dial  10  through which a user of the device may, for example, set a predetermined required value (preset value) of humidity or temperature of the gases supplied to patient  1 . The controller may also receive input from other sources, for example temperature and/or flow velocity sensors  11  and  12  through connector  13  and heater plate temperature sensor  14 . In response to the user set humidity or temperature value input via dial  10  and the other inputs, controller  9  determines when (or to what level) to energise heater plate  7  to heat the water  6  within humidification chamber  5 . As the volume of water  6  within humidification chamber  5  is heated, water vapour begins to fill the volume of the chamber above the water&#39;s surface and is passed out of the humidification chamber  5  outlet  4  with the flow of gases (for example air) provided from a gases supply means or blower  15  which enters the chamber through inlet  16 . Exhaled gases from the patient&#39;s mouth are passed directly to ambient surroundings in  FIG. 1 . 
         [0085]    Blower  15  is provided with variable pressure regulating means or variable speed fan  21  which draws air or other gases through blower inlet  17 . The speed of variable speed fan  21  is controlled by electronic controller  18  (or alternatively the function of controller  18  could carried out by controller  9 ) in response to inputs from controller  9  and a user set predetermined required value (preset value) of pressure or fan speed via dial  19 . Nasal Mask 
         [0086]    According to a first embodiment of the present invention the patient interface is shown in  FIG. 2  as a mask. It will be appreciated the patient interface could equally be a nasal mask, full face, oral mask or mouth piece, endotracheal tube or cannula by way of example. The mask includes a hollow body  102  with an inlet  103  connected to the inspiratory conduit  3 . The mask  2  is positioned around the nose of the user  1  with the headgear  108  secured around the back of the head of the patient  1 . The restraining force from the headgear  108  on the hollow body  102  and the forehead rest  106  ensures enough compressive force on the mask cushion  104 , to provide an effective seal against the patient&#39;s face. 
         [0087]    The hollow body  102  is constructed of a relatively inflexible material for example, polycarbonate plastic. Such a material would provide the requisite rigidity as well as being transparent and a relatively good insulator. The expiratory gases can be expelled through a valve (not shown) in the mask, a further expiratory conduit (not shown), or any other such method as is known in the art. 
       Mask Cushion 
       [0088]    Referring now to  FIGS. 3 and 4  in particular, the mask cushion  1104  is provided around the periphery of the nasal mask  1102  to provide an effective seal onto the face of the user to prevent leakage. The mask cushion  1104  is shaped to approximately follow the contours of a patient&#39;s face. The mask cushion  1104  will deform when pressure is applied by the headgear  1108  to adapt to the individual contours of any particular user. In particular, there is an indented section  1150  intended to fit over the bridge of the user&#39;s nose as well as a less indented section  1152  to seal around the section beneath the nose and above the upper lip. 
         [0089]    In  FIG. 4  we see that the mask cushion  1104  is composed of a inner foam cushion  1110  covered by an outer sealing sheath  1112 . The inner cushion  1110  is constructed of a resilient material for example polyurethane foam, to distribute the pressure evenly along the seal around the user&#39;s face. The inner cushion  1110  is located around the outer periphery  1114  of the open face  1116  of the hollow body  1102 . Similarly the outer sheath  1112  may be commonly attached at its base  1113  to the periphery  1114  and loosely covers over the top of the inner cushion  1110 . 
         [0090]    In the preferred embodiment shown in  FIGS. 3-6  the bottom of the inner cushion  1110  fits into a generally triangular cavity  1154  in the hollow body  1102 . The cavity  1154  is formed from a flange  1156  running mid-way around the interior of the hollow body. 
         [0091]    The outer sheath  1112  fits in place over the cushion  1110 , holding it in place. The sheath  1112  is secured by a snap-fit to the periphery  1114  of the hollow body. In  FIGS. 5-6  the periphery  1114  is shown including an outer bead  1158 . The sheath  1112  includes a matching bead  1159 , whereby once stretched around the periphery, the two beads engage to hold the sheath in place. 
       Forehead Rest 
       [0092]    A prior art nasal mask  102  including a forehead rest  106  is shown in  FIGS. 2 and 7 . The forehead rest  106  may move freely in proximity to the mask body  102  and user, but with no lateral movement or may be permanently fixed or adjustably fixed. 
         [0093]    Referring to  FIG. 7 , at the top end  142  (around the user&#39;s forehead) of the bridge member  136  harnessing slots (not shown) are provided which allow straps from the headgear to be inserted to secure the mask to the headgear. For the user&#39;s comfort one or more resilient cushions  140  are provided on the T-piece of the forehead rest  142  the top end of the bridge member  136 , to rest on the forehead of the user. The cushion  140  is constructed by injection moulding or extruding, from silicone or any foam materials as is known in the art for providing cushioning. In  FIG. 7  a second cushion  143  is shown at the other end of the section  142 . 
       Forehead Rest Cushion 
       [0094]    Referring now to  FIGS. 8 and 9  the prior art forehead rest cushion  140  is illustrated. The cushion  140 , in cross section, includes an outer curved member  210  and a inner curved member  212  both of which are attached at each end to a straight base member  214 . The inner curved member  212  is a substantially similar curved shape to the outer curved member  210 . The inner member  212  and outer member  210  may be coterminous, the inner member may attach to the outer member  210  or both may attach to the base  214  separately. 
         [0095]    When the cushion  140  comes into contact with the user&#39;s face the outer curved member  210  deforms as more pressure is applied to the cushion towards the face. This comprises of the first mode of deformation. Once the outer curved member  210  deforms enough to contact the inner curved member a second mode of deformation occurs. 
         [0096]    As will be appreciated if the outer curved member is flatter than the second curved member  212  the first mode requires less force. The relative curvature and thickness of each can be varied to give a characteristic first mode and second mode. Once in the second mode of deformation extra force is required to deform both the first curved member  210  and the second curved member  212 . This configuration described above results in more even deformation force across the load bearing surface of the cushion  216  and also results in a more progressive force of cushioning when the cushion  120  is deformed. 
         [0097]    A further prior art embodiment of a forehead rest cushion is shown in  FIGS. 10 and 11 . This forehead rest cushion  140  has an outer curved member  220  attached at either end to a straight base member  222 . A inner inverted curved member  224  is inverted with respect the outer curved member  220  and is attached at either end two points on the  226 ,  228  on the outer curved member  220 . The inner inverted curved member is lower in overall height than the outer curved member  220  such that a first mode of deformation occurs when the outer curved member  220  is deformed. A second mode of deformation occurs when the inner inverted curved member  224  contacts the base member  222 . The outer curved member  220  and the inner inverted curved member  224  deform simultaneously. The forces across the load bearing surface  230  are further distributed by virtue of a generally quadrilateral member  232  including as one side the base member  222  which attaches over the inner inverted curved member  220  approximately at its ends and at its load bearing point  234 . The quadrilateral member  232  provides additional stiffness and reduces lateral deformation. 
         [0098]    These prior art forehead rests have a base member that includes a flange  240  which engages with a slot  2138  in the forehead rest  106  to lock the forehead rest cushion in place. The flange  240  first slides through aperture  2139  as seen in  FIG. 12 . 
         [0099]    In the preferred forms of the forehead rest cushion of the present invention will now be described with reference to  FIGS. 13 to 26 ,  31  and  32 . With each of the embodiments as described in relation to these figures the forehead rest cushion or pad allows for a controlled compression of the cushion. Each cushion is capable of being compressed under a force and will return to its original position (as shown in the Figures) when the force ceases. 
         [0100]    A first embodiment of the forehead rest cushion is shown in  FIG. 13 . This forehead rest cushion  300  has a flange  301  that is able to be attached to a forehead rest, such as that rest  106  shown in  FIG. 7  or  12 . The flange  301  slides through the aperture  2139  in the T-piece  2140  of the forehead rest  106 . The cushion  300  is substantially rectangular in shape with an upper wall  302  and lower wall  303 , with the flange being attached to the lower wall  303 . The side walls are corrugated or concertinaed such that these walls  304 ,  305  collapse when a force is placed on the upper wall  302 . As described above, as the cushions are made from a plastics material, such as silicone or foam, the folds forming the side walls will return to the original form when any compression force ceases. 
         [0101]      FIG. 14  shows a second embodiment of a forehead rest cushion of the present invention. This forehead rest cushion  306  is a cushion that is in the general shape of a parabolic cone. The cushion has an open top  307  that can be seen in  FIG. 15 , this open top  307  allows the edge  308  of the cushion  306  to roll inwards when the top of the cone shaped cushion is compressed, or a force placed air on. This cushion may be attached to a forehead rest, such as the T-piece forehead rest as shown in  FIGS. 7 and 12  by any appropriate means, for example, gluing or the like and may include a flange such as that described above with reference to  FIG. 13 . 
         [0102]    In alternative embodiments any of the forehead rest cushion of the present invention as shown in the Figures may have an alternative attachment mechanism such as an arrow head type barb or protrusion, which fits into apertures on the forehead rest. Alternatively, any of the cushions may be provided with an aperture in place of the flange that is able to be slid about an arm of the forehead rest. 
         [0103]    A third embodiment of the forehead rest cushion of the present invention is shown in  FIGS. 17 ,  18  and  19 . This cushion  309  has a conical body  310  with a flattened circular top  311 . This cushion is either injection moulded, extruded, or stamped from a sheet of material and is preferably made of a thermoplastic elastomer, silicone or foam. Again, when a force is applied to the top  311  the inner areas of the top roll inwards down towards the top of the cone body  310 . For example, as shown in  FIG. 19  in a section view when a force A is placed on the top  311  the inner area of the top  311  moves downwards and the outer areas, shown as  311 ′, move upwards or simply adjust to the shape of the area of user&#39;s forehead it abuts. 
         [0104]    Reference is now made to  FIGS. 20 and 21  where the force embodiment of the forehead rest cushion of the present invention is shown this forehead rest cushion  312  is of a hemispherical shape and also allows for a two stage cushioning when a force is placed upon it. The cushion  312  has a hemispherical body  313  suspended above a platform  314  and also has a flange  315  allowing the cushion  312  to be slotted into an aperture in a forehead rest, such as that described above. The hemispherical body  313  is suspended above platform  314  on small supports  316 ,  317 . This cushion  312  is preferably moulded from a thermoplastics material, silicone or foam. 
         [0105]    A fifth embodiment of the forehead rest cushion is shown in  FIG. 22 . The cushion  318  is shaped in the form of an “M” or generally rectangular with a recess  319  formed in the top wall  320  of the cushion  318 . Therefore, two inner vertical walls  321 ,  322  are formed parallel to the outer vertical walls  323 ,  324 . When a force is applied to the upper wall  320  the recessed part  319  and vertical walls  322 ,  321  are pushed downwards towards the lower wall  325 . When the apex  326  of the recessed part  319  hits the lower wall  325  the cushion may still be compressed, but at a different rate of force such that the compression of this cushion  318  is a two stage compression. The recess  319  in the middle of the cushion  318  therefore provides more uniform pressure across the top wall  320  of the cushion. As with other forms as described above this forehead cushion  318  is supplied with a flange  327  attached to the lower wall  325  allowing the cushion  318  to be attached to the forehead rest. 
         [0106]    Reference is now made to  FIG. 23  where a sixth embodiment of the forehead rest cushion of the present invention is shown. This cushion  328  is of a similar form to that described in relation to  FIG. 13 , but its top or upper wall  329  is curved and the side walls  330 ,  331  merely form one corrugation or fold. When a force is placed upon the upper wall  329  the side walls  330 ,  331  fold in upon themselves. Again, this cushion has a flange  332  attached to its lower wall  333  to allow the cushion  328  to be attached to the forehead rest. 
         [0107]    A seventh embodiment of the forehead rest cushion as shown in  FIG. 24 , this cushion is very similar in form to that of the prior art cushion as shown in  FIG. 8  but its upper wall  335  is split in two and its inner wall  336  is horizontal in nature and not curved. Again, this cushion  334  has a flange  337  that allows it to be attached to a forehead rest. This cushion provides a two stage compression where the inner wall provides stability to the cushion  334 . 
         [0108]    The eighth embodiment of the forehead rest cushion of the present invention is shown in  FIG. 25 . This cushion  318  has a base member  319  having a flange similar to as described above in relation to the prior art cushions. The flange  340  allows the cushion  338  to be attached to a forehead rest. Two vertical walls  341 ,  342  extend upwards nearer the centre of the base member  339 , and a curved upper member in the shape of a partial oval is attached above the vertical walls  341 ,  342 . When a force is placed on the curved upper member  343  the vertical walls  341 ,  342  initially support the force placed on the upper member  343 . The outer edges  344 ,  345  of the upper member  343  are able to freely roll inwards to give further controlled support to the cushion  338 . 
         [0109]    A ninth embodiment of the forehead rest cushion of the present invention is shown in  FIG. 26 . This cushion  346  has a base member  347  and a flange attached to it to enable the cushion to be attached to a forehead rest. Extending outwards and upwards from the edges of the base member  347  are arms  349 ,  350 . These arms  349 ,  350  are curved inwardly towards one another and may overlap. When a force is placed on the upper  350  arm, the arm  350  moves down towards the lower arm  349 . If enough force or a continued force is provided to the upper arm  350 , the upper arm  350  will continue to compress against and push the lower arm  349  towards the centre of the cushion  346  and the base member  347 . These independent inwardly rolled arms  349 ,  350  allow for a two stage compression that is controlled when a force being placed on the upper arm  350 . 
         [0110]    A fourteenth embodiment forehead rest cushion of the present invention is shown in  FIG. 31 . This cushion  351  has a similar shape to the prior art cushion of  FIG. 9  and includes a base member  354  and a flange  353  which engages with a slot  2138  in the forehead rest to lock the forehead rest cushion in place. The flange  353  slides through and fixes in the aperture  2139  as seen in  FIG. 12 . The cushion  351  is substantially rectangular in shape but with an upper wall  352  that is slightly curved at its edges where it meets the side walls  355 ,  356  of the cushion. The upper wall is thicker in width than the side walls  355 ,  356  to provide additional strength and control to the cushion. Furthermore, the relative thickness of the upper wall  352  compared to the side walls  355 ,  356  prevents the cushion  351  from caving in. This helps provide a uniform pressure on the user&#39;s forehead. 
         [0111]    A further embodiment of a forehead rest cushion is shown in  FIG. 32 . This cushion  357  is exactly the same shape as that cushion of  FIG. 31 , but this cushion has an additional curved short wall  358  extending below and following the contour of the upper wall  359 . This short wall  358  provides for additional support to the upper wall  359  when a force is placed upon it. 
         [0112]      FIGS. 27 to 30  and  33  illustrate forehead rest cushions that can be adjusted to a user&#39;s preference. Firstly referring to  FIG. 27  a rotating substantially circular or cam shaped cushion  360  rotatably mountable between two legs  361 ,  362 , which are each attached and extend outwards from the forehead rest or mask base, for example, one on either side of the T-piece as shown in  FIG. 12 . As the cushion  360  rotates in the direction of Arrow B the offset is increased or decreased. 
         [0113]      FIG. 28  shows a further embodiment of the cushion of  FIG. 27 . This cushion  363  additionally has a plurality of fixed attachments  364 , similar to the flange on the cushions described above. Each of these can be attached to the forehead support in turn to provide an adjustable cushion. 
         [0114]    A twelfth embodiment of a forehead rest cushion of the present invention is shown in  FIG. 29 . This cushion  365  is effectively a strap or flexible elongate member (preferably made of a flexible plastics material) attached to one arm  366  of a T or to an I piece of a forehead rest. In the case of a T-shaped forehead rest, such as that shown in  FIG. 12 , two cushions of this type would be provided one for each of the two arms of the T-shaped forehead rest. The strap  365  is provided with a pair of protrusions  367 ,  368  at each of its ends  369 ,  370  such that a recess is formed between each set of protrusions. Each end  369 ,  370  is fixed to the arm  366  by appropriate means, such as a sleeve  371  or aperture  372  on the arm  366 . In particular, the upper end  369  of the strap  365  is fixed to the arm  366  in the aperture  372  and the lower end  370  is slideably adjustable by way of a slideable sleeve  371  capable of sliding and being fixed into any one of a number of recesses  373  formed on the edge  374  of the arm  366 . 
         [0115]    A further embodiment of an adjustable forehead rest cushion is shown in  FIG. 30 . This adjustable cushion  375  is a strap or flexible elongate member where a first end  376  of its two ends  376 ,  377  is fixed to an arm  379  (similar to that arm  366  described above). The second end  377  of the two ends is threaded about and around such that a substantial part of the strap forms a circular shape that provides a cushioning effect should a force be placed upon it. The second end  377  after being threaded through an aperture  381  in the arm  379 , and possibly an further holding sleeve  380  formed on the arm  379 , is fixed to the other side of the arm  379 , for example by pressing a protrusion  382  through a hole  383  formed in the strap  375 . The size of the circular cushion formed can be adjusted as a plurality of spaced apart holes are provided in the strap and the strap can be pulled through the arm and the protrusion  382  fixed in each hole dependent on the requirements of the user. 
         [0116]    Yet still a further embodiment of an adjustable forehead rest cushion is shown in  FIG. 33 , where a double loop strap  384  is formed into two arced cushions  385 ,  386 . Each of the apexes of the arced cushions  385 ,  386  would in use rest against a user&#39;s forehead to provide additional comfort while wearing a mask or interface similar to that described above. The strap  384  has abutments  387 ,  388  formed at each end that fit under lips  389 ,  390  formed in an arm  391  (such as, a one T-piece arm of the forehead rest as described above in relation to  FIG. 12 , or an I shaped forehead rest as is known in the prior art and particularly described in New Zealand patent application number 524439 of Fisher &amp; Paykel Healthcare Limited). The middle section  392  of the strap  384  has a plurality of notches  393  cut in each of its edges. The strap  384  is threaded through two apertures formed in the middle of the arm  391 , such that a substantial portion of the middle section  392  extends out from the arm  391  in an opposing direction to the arced cushions  385 ,  386 . The middle section  393  can be pulled further through the arm or to pushed back through the apertures in the arm using the notches  393  as incremental positions for the middle section to be held in, to decrease or increase the size of the arced cushions  385 ,  386 . 
         [0117]    The forehead rest cushion embodiments shown in  FIGS. 27 to 30  and  33  are all user adjustable. In particular the forehead rest cushions shown in these figures are height adjustable and allow the user to adjust the amount cushioning the forehead rest cushions can provide. The height of the forehead rest cushion is the distance between the forehead rest  106  and the face or forehead of the user. The height adjustable forehead rest cushion allows a user to adjust the distance between the forehead rest and the lace of the patient. This allows a user to adjust the amount of cushioning provided by the forehead rest cushion. 
         [0118]    In other forms of the forehead rest cushion of the present invention the cushion may be an inflatable member that can be manually inflated using a syringe or a hand or finger operated compression pump, or automatically inflated using a compressible reservoir or the like.

Technology Classification (CPC): 0