Abstract:
A user interface for delivering CPAP includes a forehead adapted with a deformable attachment between the interface and the support. In the preferred embodiment the interface is a mask which substantially seals against the face of the user without substantial pressure thereto and delivers said gases to the nasal cavity and/or oral cavity and/or throat.

Description:
FIELD OF INVENTION  
         [0001]    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  
         [0002]    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.  
           [0003]    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.  
           [0004]    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  
         [0005]    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.  
           [0006]    Accordingly in one aspect the present invention consists in  
           [0007]    a user interface, in use in fluid communication with a supply of gases,  
           [0008]    a forehead support adapted to in use rest on the forehead of a user, and  
           [0009]    a deformable or flexible attachment between said interface and said support.  
           [0010]    Preferably said interface is a mask, said mask and said support being configured to in use substantially seal against the face of a user without substantial pressure there to and deliver said gases to the nasal cavity and/or oral cavity and/or throat of a user.  
           [0011]    Preferably said deformable attachment comprises a malleable section between said interface and said support.  
           [0012]    Preferably said malleable section comprises a metal insert between said interface and said forehead rest, where said insert is malleable to the extend that it may be configured to a certain angle of said forehead rest to said interface and will retain said angle in use attached to user&#39;s head.  
           [0013]    Preferably said insert is at least in part encapsulated by and/or engaged with said interface and/or said support.  
           [0014]    Preferably said device further comprising a pivoting attachment between said deformable attachment and said interface.  
           [0015]    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.  
           [0016]    The invention consists in the foregoing and also envisages constructions of which the following gives examples. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    One preferred form of the present invention will now be described with reference to the accompanying drawings in which;  
         [0018]    [0018]FIG. 1 is a block diagram of a humidified continuous positive airway pressure (system) as might be used in conjunction with the present invention,  
         [0019]    [0019]FIG. 2 is an illustration of the nasal mask in use according to the preferred embodiment of the present invention,  
         [0020]    [0020]FIG. 3 shows a perspective view of the mask with cushion,  
         [0021]    [0021]FIG. 4 is a cutaway view of the mask showing the cushion,  
         [0022]    [0022]FIG. 5 is a cutaway view of the periphery of the outer membrane,  
         [0023]    [0023]FIG. 6 is a cutaway view of the periphery of the mask body portion,  
         [0024]    [0024]FIG. 7 is a side view of the forehead rest in isolation, and  
         [0025]    [0025]FIG. 8 is a perspective view of the forehead rest in isolation. 
     
    
     DETAILED DESCRIPTION  
       [0026]    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.  
         [0027]    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.  
         [0028]    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.  
         [0029]    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 .  
         [0030]    Nasal Mask  
         [0031]    According to a first embodiment of the present invention the patient interface is shown in FIG. 2 as a mask. Alternatively it may be a nasal mask, full face mask, endotracheal tube, oral mask or mouthpiece, or nasal cannula 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.  
         [0032]    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.  
         [0033]    Mask Cushion  
         [0034]    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.  
         [0035]    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 .  
         [0036]    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.  
         [0037]    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.  
         [0038]    Forehead Rest  
         [0039]    In the preferred embodiment of the present invention the interface includes a 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  angle to be adjusted in relation to the user but with no lateral movement.  
         [0040]    At a T-section  142  at the top end (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 the T-section  142  at the top end 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. The cushions lock into slots  137  in the T-Section  142   
         [0041]    In a further embodiment the forehead rest  106  described previously may include a weakened section at its base which allows the joining member to pivot from the hollow body. The extent of flexibility of this joint can be varied by its thickness to any desired strength. 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.  
         [0042]    Particularly referring to FIGS. 7 and 8 the forehead rest  106  is shown including a flexible or malleable insert  204 . The preferred embodiment the malleable insert  204  comprises a metal strip joining the hollow body  102  to the forehead rest  106 . The metal can be chosen from anyone of a number of metals known in the art to provide enough malleability to be bend to a particular angle and enough stiffness to retain the angle once installed on the patient. Stiffness can be configured by choice and thickness of insert  204 . An example is 1 mm thickness. The malleable insert  204  maybe connected to the hollow body  102  by mounting  206 .  
         [0043]    Mounting  206  may include additional pivot ( 207 , FIG. 8) or adjustment mechanisms. Additionally forehead rest  106 , insert  204  and/or body  102  may be integral or encapsulated. Preferably insert  204  is supported within a mould during fabrication. Polycarbonate or other suitable plastics are preferably injection moulded to encapsulate each end of the insert, into the body  102  and the forehead rest  106  respectively. Preferably the insert  104  displays a limited degree of work hardening over the range of plastic deformation. For example soft alloys are less likely to snap after a large amount of bending back and forwards. Alloys involving aluminium or copper are possible constructions. Portions of the insert, body and/or forehead rest may be encapsulated by a pliable material eg silicone.