Abstract:
A device for delivering a supply of gases to a user comprising: a patient interface, in use in fluid communication with said supply of gases, a forehead support adapted to pivot about said interface and in use rest on the forehead of a user and configurable at least in an adjustment mode for selecting a desired fixed relation and a secured mode for securing said desired fixed relation. In one embodiment of the patient interface a mask seals against the face of said user and deliver said 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 PCT/NZ01/00110 filed 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 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 duty 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]    Accordingly in one aspect the present invention consists in a patient interface, in use in fluid communication with said supply of gases,  
           [0008]    a forehead support adapted to pivot about said interface and in use rest on the forehead of a user and means for securing said forehead support in a substantially fixed relation to said interface and configurable at least in an adjustment mode for selecting a desired fixed relation and a secured mode for securing said desired fixed relation.  
           [0009]    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.  
           [0010]    Preferably said desired fixed relation lies at any point within a predetermined angular range.  
           [0011]    Preferably said means for securing further comprises a friction engagement whereby said bridge member may be selectively engaged to said nasal mask in said desired fixed relation by a friction engagement.  
           [0012]    Preferably said friction engagement comprises an adjustable clamp engaging at least a first flange of said nasal mask with a second flange on said bridge member in a fixed position relative thereto.  
           [0013]    Preferably said clamp comprises a elongate member extending through apertures in at least said first flange and said second flange whereby the rotation thereof, through a helical thread acting on either said first flange, said second flange, said bridge member and/or said interface, thereby increasing or decreasing the compressive pressure of said first flange on said second flange and thereby varying the frictional engagement there between.  
           [0014]    Preferably said first flange said second flange are flat.  
           [0015]    Preferably said first flange and said second flange are conical.  
           [0016]    In a second aspect a CPAP system for delivering gases to a user the improvement comprising  
           [0017]    a user interface for communicating said gases to said user accordingly to the device claimed in any of the proceeding paragraphs.  
           [0018]    Preferably the improvement further comprising  
           [0019]    a humidifier in fluid communication with said interfaces variably humidifies said gases prior to delivery to said user.  
           [0020]    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.  
           [0021]    The invention consists in the foregoing and also envisages constructions of which the following gives examples. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]    One preferred form of the present invention will now be described with reference to the accompanying drawings in which;  
         [0023]    [0023]FIG. 1 is a block diagram of a humidified continuous positive airway pressure (system) as might be used in conjunction with the present invention,  
         [0024]    [0024]FIG. 2 is an illustration of the nasal mask in use according to the preferred embodiment of the present invention,  
         [0025]    [0025]FIG. 3 shows a perspective view of the mask with cushion,  
         [0026]    [0026]FIG. 4 is a cutaway view of the mask showing the cushion,  
         [0027]    [0027]FIG. 5 is a cutaway view of the periphery of the outer membrane,  
         [0028]    [0028]FIG. 6 is a cutaway view of the periphery of the mask body portion,  
         [0029]    [0029]FIG. 7 shows the forehead rest in isolation,  
         [0030]    [0030]FIG. 8 shows the pivoting forehead rest with a locking mechanism,  
         [0031]    [0031]FIG. 9 is a perspective view of the mask showing the friction engagement,  
         [0032]    [0032]FIG. 10 is an alternate perspective view of the mask showing the friction engagement, and  
         [0033]    [0033]FIG. 11 is a cross section view of the friction engagement. 
     
    
     DETAILED DESCRIPTION  
       [0034]    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.  
         [0035]    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.  
         [0036]    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.  
         [0037]    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 .  
         [0038]    Mask  
         [0039]    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.  
         [0040]    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.  
         [0041]    Mask Cushion  
         [0042]    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.  
         [0043]    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 .  
         [0044]    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.  
         [0045]    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.  
         [0046]    However it will be appreciated the invention is not limited to this form of sealing.  
         [0047]    Forehead Rest  
         [0048]    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.  
         [0049]    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 .  
         [0050]    At the top end  2142  (around the user&#39;s forehead) of the bridge member  2136  harnessing slots  2138  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  2140  are provided underneath the top end  2142  of the bridge member  2136 , which rest on the forehead of the user. The cushion  2140  might be constructed of silicon or any foam materials as is known in the art for providing cushioning.  
         [0051]    In a firer embodiment the forehead rest  106  described previously may include a weakened section  2130  at its base  2132  which allows the joining member  2136  to pivot from the hollow body  102 . 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  2136  is hinged at its base  2132  to either side of the inlet passage. Again the member would then extend to the forehead.  
         [0052]    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.  
         [0053]    In a still further embodiment shown in FIGS.  9  to  11  the bridge member  430  according to the present invention is shown including a friction engagement  432  with the mask body  434 . In this embodiment the mask body  434  is shown with an elbow connector  436  connected to the inlet conduit  438 . An adjustment knob  440  provided on the side of the bridge member  432  allows adjustment. With the knob  440  in a loosened position the bridge member  430  may be pivoted to any desired angle with respect to the mask body  434 . Once in the desired position the knob  440  may be configured to a tightened position whereby the angle of the bridge member  430  relative to the mask body  434  is substantially fixed by virtue of the friction engagement in the pivot parts. Knob  440  may also be configured in a partially tightened position whereby the pivot angle may be adjusted by applying a large force between the two.  
         [0054]    In more detail shown in FIG. 11 the knob  440  includes a helical thread engaging with a reciprocal helical thread  441  on pin  442  running transversely through the bridge member  430 . The pin also runs through apertures in two flanges  444 ,  445  extending up from the mask body  434  and an internal flanges  446  from the bridge member  430 . In this fashion the body flanges  444 ,  445  and bridge flange  446  may frictionally engage (optionally also with the inner surfaces of the bridge member  430 ) once the knob  440  is in a tightened position. More preferably washer  448  is provided between body flanges  444 ,  445  and bridge flange  446 . Washer  448  improves the friction engagement and may be formed as a single hard rubber inset, or two separate washers. Adjustment may either be allowed in a finite number of predetermined positions or more preferably may be completely variable.  
         [0055]    In a further variation the body flange and bridge flange may be conical, or any other configuration allowing pivoting as well as engagement in a desired relation