Abstract:
A device for delivering a supply of gases to a user comprising: a patient interface, in use in fluid communication with the supply of gases, a forehead support adapted to pivot about the interface and in use rest on the forehead of a user. The pivot angle restricted in use by positioning or adjustment of a pivot stop on the support or interface. In one embodiment of the patient interface; a mask seals against the face of the user and deliver the gases to the nasal cavity and/or oral cavity and/or throat of said user without substantial pressure on the users face.

Description:
[0001]    This is a Continuation-In-Part of PCr/NZ01/00110 filed on Jun. 14, 2001.  
         FIELD OF INVENTION  
         [0002]    This invention relates to patient interfaces particularly though not solely for use in delivering CPAP therapy to patients suffering from obstructive sleep apnoea (OSA).  
         BACKGROUND OF THE INVENTION  
         [0003]    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.  
           [0004]    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.  
           [0005]    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  
         [0006]    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.  
           [0007]    Referring particularly to FIGS.  9  to  11  the present invention is illustrated with a pivoting bridge member  300  and an adjustable pivot stop  302 . The bridge member  300  is attached to and pivots about pins  304  extending from in the side of the upwardly extending inlet conduit  306  of the mask  305 . The pins  304  engage with matching apertures  308  in the bridge member  300 .  
           [0008]    The pivot stop  302  may be adjusted into a number of predetermined positions whereby the angle to which the forehead rest member  300  can freely pivot is restricted. Accordingly the pivot stop  302  requires an adjustable engagement with the bridge member  300 . Preferably the engagement is provided with a locking clip  310  which engages with any one of a number of mating depressions or protrusions  312  in the bridge member  300 . Alternatively the engagement could be provided by for example a friction engagement including some tensioned member (not shown) frictionally engaging the bridge member  300 . The tensioned member could be releasable to allow movement and engagable to fix the position. Further variations includes simply adjusting the pivot stop eg: its angel as opposed to moving it to vary the angle restriction.  
           [0009]    For example as shown in FIG. 9 with the pivot stop  302  in a forward position the angle (FIG. 10, 314) of movement is restricted to very little or a small range of movement with the forward rest cushion  314  positioned at the maximum distance away  315  from the axis of the inlet conduit  306 . As shown in FIG. 11 with the pivot stop  302  in a backward position the angle  314  of movement is much less restricted such that the cushion  316  may be pivoted to a position  318  much more proximate the inlet conduit  306 .  
           [0010]    Accordingly in one aspect the present invention consists in a device for delivering a supply of gases to a user comprising:  
           [0011]    a user interface, in use in fluid communication with a supply of gases,  
           [0012]    a forehead support adapted to freely pivot in use over a restricted pivot angle about said interface and in use rest on the forehead of a user, and  
           [0013]    a pivot stop associated with said interface or said support, configured such that the extent of said restricted pivot angle determined by the relative adjustment or positioning of said pivot stop  
           [0014]    Preferably said interface is a mask and said mask and said support being configured to in use substantially seal against the face of said user without substantial pressure there to and deliver said gases to the nasal cavity and/or oral cavity and/or throat of said user.  
           [0015]    Preferably said pivot stop is adjustably engaged with or in relation to said forehead rest whereby said pivot angle is restricted by the relative position of said pivot stop to said interface.  
           [0016]    Preferably said adjustment or positioning relates to one of two or more predetermined adjustment settings or positions.  
           [0017]    Preferably said adjustment or positioning lies at any point within a predetermined angular range.  
           [0018]    Preferably said pivot stop may be locked in any one of a number of plurality of predetermined positions on or in relative to said support.  
           [0019]    Preferably said pivot stop may be frictionally engaged in a selected position with or in relation to said support.  
           [0020]    In a second aspect, in a CPAP system for delivering gases to a user the improvement comprising;  
           [0021]    a user interface for communicating said gases to said user accordingly to the device claimed in any of the proceeding claims.  
           [0022]    Preferably the improvement further comprising;  
           [0023]    a humidifier in fluid communication with said interface configured to variably humidifies said gases prior to delivery to said user.  
           [0024]    To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting  
           [0025]    The invention consists in the foregoing and also envisages constructions of which the following gives examples. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0026]    One preferred form of the present invention will now be described with reference to the accompanying drawings in which;  
         [0027]    [0027]FIG. 1 is a block diagram of a humidified continuous positive airway pressure (system) as might be used in conjunction with the present invention,  
         [0028]    [0028]FIG. 2 is an illustration of the nasal mask in use according to the preferred embodiment of the present invention,  
         [0029]    [0029]FIG. 3 shows a perspective view of the mask with cushion,  
         [0030]    [0030]FIG. 4 is a cutaway view of the mask showing the cushion,  
         [0031]    [0031]FIG. 5 is a cutaway view of the periphery of the outer membrane,  
         [0032]    [0032]FIG. 6 is a cutaway view of the periphery of the mask body portion,  
         [0033]    [0033]FIG. 7 shows the forehead rest in isolation,  
         [0034]    [0034]FIG. 8 shows the pivoting forehead rest with a locking mechanism,  
         [0035]    [0035]FIG. 9 is a perspective view of the mask showing the friction engagement,  
         [0036]    [0036]FIG. 10 is an alternate perspective view of the mask showing the friction engagement, and  
         [0037]    [0037]FIG. 11 is a cross section view of the friction engagement. 
     
    
     DETAILED DESCRIPTION  
       [0038]    The present invention provides improvements in the delivery of CPAP therapy. In particular a patient interface is described which is quieter for the user to wear and reduces the side 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.  
         [0039]    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.  
         [0040]    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.  
         [0041]    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 .  
         [0042]    Mask  
         [0043]    According to a first embodiment of the present invention the patient interface is shown in FIG. 2 as a mask. This may be also a nasal mask, a full face mask, a oral mask endotracheal tube, nasal cannula or other breathing assistance interface as are known in the art. 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.  
         [0044]    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 simple vent (not shown), a further expiratory conduit (not shown), or any other such method as is known in the art.  
         [0045]    Mask Cushion  
         [0046]    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  104  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.  
         [0047]    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 .  
         [0048]    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.  
         [0049]    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. However it will be appreciated the invention is not limited to this form of sealing.  
         [0050]    Forehead Rest  
         [0051]    In the preferred embodiment of the present invention the nasal mask  2102  includes a pivoting forehead rest  106  (seen in FIGS. 2 and 7). The attachment of the forehead rest  106  to the hollow body  102  effectively allows the forehead rest  106  to pivot towards and away from the user but with no lateral movement.  
         [0052]    In one form shown in FIG. 7, pins  2130 . are provided mounted on a base  2132  attached to the hollow body  102 . These pins  2130  are co-axial within cylinders  2131  mounted on a bridge member  2136 .  
         [0053]    At the top end  142  (around the user&#39;s forehead) of the bridge member  136  harnessing slots  138  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 underneath a T-Section  142  at the top end  142  of the bridge member  136 , which rest on the forehead of the user. The cushion  140  might be constructed of silicon or any foam materials as is known in the art for providing cushioning.  
         [0054]    In a further embodiment the forehead rest described previously may include a weakened section at its base which allows the joining member to pivot from the hollow body. The bridge member extends up to the forehead of the user In a further alternative the mask may include a vertical upwardly extending inlet. In this case the member is hinged at its base to either side of the inlet passage Again the member would then extend to the forehead.  
         [0055]    In a still further embodiment shown in FIG. 8 the forehead rest  106  is shown with the pivoting action which can be locked in a single position. As before the bridge member  136  pivots by virtue of pins from the hollow body  102  co-operating with cylinders  131  on the bridge member  136 . The locking action is provided by an engaging clip  200  which is attached through an aperture at the base of the bridge member  136 . The lock and clip  200  has a number of ribs which engage with at least two ribs on the interior of the aperture which allows it to lock and place it in at least an upper position and a lower position. In the upper position the locking clip  200  is clear of the hallow body  102  and allows the bridge member  136  to pivot freely. In the lower position the locking pin  200  engages with a cavity on the surface of the said hollow body  102  which locks said bridge member  136  at a predetermined angular position with respect to said hollow body  102 . In the preferred embodiment this position provides the maximum off set of the upper section of the mask from the bridge of the patients nose.  
         [0056]    Referring particularly to FIGS.  9  to  11  the present invention is illustrated with a pivoting bridge member  300  and an adjustable pivot stop  302 . The bridge member  300  is attached to and pivots about pins  304  extending from in the side of the upwardly extending inlet conduit  306  of the mask  305 . The pins  304  engage with matching apertures  308  in the bridge member  300 .  
         [0057]    The pivot stop  302  may be adjusted into a number of predetermined positions whereby the angle to which the forehead rest member  300  can freely pivot is restricted. Accordingly the pivot stop  302  requires an adjustable engagement with the bridge member  300 . Preferably the engagement is provided with a locking clip  310  which engages with any one of a number of mating depressions or protrusions  312  in the bridge member  300 . Alternatively the engagement could be provided by for example a friction engagement including some tensioned member (not shown) frictionally engaging the bridge member  300 . The tensioned member could be releasable to allow movement and engagable to fix the position. Further variations includes simply adjusting the pivot stop eg: its angel as opposed to moving it to vary the angle restriction.  
         [0058]    For example as shown in FIG. 9 with the pivot stop  302  in a forward position the angle (FIG. 10, 314) of movement is restricted to very little or a small range of movement with the forehead rest cushion  314  positioned at the maximum distance away  315  from the axis of the inlet conduit  306 . As shown in FIG. 11 with the pivot stop  302  in a backward position the angle  314  of movement is much less restricted such that the cushion  316  may be pivoted to a position  318  much more proximate the inlet conduit  306 .