Abstract:
A mouthpiece for oral delivery for oral delivery of CPAP treatment has a vestibular shield for location between the teeth and lips/cheeks of a wearer. The vestibular shield is dimensioned to extend laterally into the buccal vestibule and vertically to overlap the gums. The vestibular shield is formed from a very supple material. A gases pathway is provided through the vestibular shield and may include a hard plastic insert through the shield, including a standard breathing conduit connection at its outer end. A short stub conduit on the outlet side of the shield passes between the wearers upper and lower teeth.  
     A connection for connecting the mouthpiece to a breathing circuit is also provided which reduces the transfer of forces caused by movement therebetween. The connection may include a short length of highly flexible gases conduit, an elbow and a swivel connection.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of Invention  
           [0002]    This invention relates to a system for oral delivery of gases pressurized above ambient, and in particular, to a system, including a novel mouthpiece, for the oral delivery of air in continuous positive airway pressure (CPAP) treatments of sleeping disorders such as sleep apnoea.  
           [0003]    2. Description of the Prior Art  
           [0004]    Sleep apnoea treatments have been significantly advanced with the introduction of continuous positive airway pressure (CPAP) treatments. These treatments, as introduced, involve the supply of gases from a gases supply or blower to a patient through a conduit and nasal mask to provide an elevated internal pressure in the users airways to assist the muscles to keep the airways open. This airstream is provided to the user through a nasal mask applied over the nose and held in place by a harness. This configuration has been almost universally adopted based on the well known observation that humans show a decided preference for nasal breathing during sleep. For this reason, little development has been undertaken into other possible methods of providing the pressurized airstream to a user.  
           [0005]    Oral delivery is suggested in EP 818, 213, which shows an apparatus for oral delivery of air in a CPAP treatment. The apparatus includes a mouthpiece adapted to fit inside the mouth between the roof of the mouth, the hard palate, and the tongue, and having a periphery which can be gripped between the teeth. It is thought by the applicants that this is significantly more intrusive than is necessary and is liable to movement and consequent discomfort (although not outright removal) under the relaxation of sleep. It has the additional disadvantage that with the user fully relaxed, such as in the case of sleep, a distension in the user&#39;s jaw and subsequent opening of the mouth can reduce the sealing effectiveness of the mouthpiece and reduce the efficacy of the CPAP treatment.  
           [0006]    Because the mouthpiece in EP 818,213 is gripped between the user&#39;s teeth, a further disadvantage results in that the mouthpiece requires custom orthodontic fitting to ensure that the mouthpiece matches the user&#39;s mouth and teeth layout. Custom orthodontic fitting is time consuming and removes the capability of effective mass manufacture. Consequently, the mouthpiece in EP 818,213 is expensive, creating a significant barrier to the patient adoption of the device.  
           [0007]    A similar gases delivery mouthpiece, for use with a respirator, is shown in WO 90/03199. WO 90/03199 discloses an orthodontic device which is adapted to be gripped between the jaws of a user and to accommodate the user&#39;s teeth within a series of upper and lower cavities. A base member of the mouthpiece is shaped and fits against the hard palate of the user. This mouthpiece again has the disadvantage of requiring custom orthodontic fitting. Furthermore, as a result of the mouthpiece&#39;s substantial thickness and size, the mouthpiece is substantially rigid in the vestibule regions of the mouth. The mouthpiece is clamped in place by an outer shield which engages the outside of the user&#39;s lips.  
           [0008]    A paper by E Veres entitled “Clinical trial of an oral vestibular shield for the control of snoring” (Journal of the Dental Association of South Africa, January 1993) describes the use of a shield intended to be retained in the vestibule of the mouth to seal the mouth and to promote nasal breathing which has been conventionally considered to be more beneficial than oral breathing. Humidified CPAP treatments delivered orally, however, actually derive greater benefit than those delivered nasally because secondary leakage through the nasal passages during oral delivery is significantly less than oral leakage during nasal delivery. The shield depicted in the paper is formed from flexible ethylene vinyl. The shield is custom trimmed and is custom fitted by heating to a malleable temperature and deformed by applied pressure.  
           [0009]    Other possible mouthpiece designs are shown for example by use in self contained underwater breathing apparatus systems, for example as depicted in U.S. Pat. No. 4,862,909. This mouthpiece is a mouth guard type and is clamped between the teeth. A flange extends both in front of and behind the teeth.  
           [0010]    Prior art mouthpieces are not well adapted for use in CPAP treatments because they are intended for conscious gripping by the user, and have been found subject to accidental removal with a user in a completely relaxed state such as sleep. The present invention overcomes this problem and present several other advantages which will become apparent upon a reading of the attached specification, in combination with a study of the drawings.  
         SUMMARY OF THE INVENTION  
         [0011]    It is an object of the present invention to provide a system for oral delivery of gases, and/or a mouthpiece for oral delivery of gases, which goes some way toward overcoming the above disadvantages or which will at least provide the public with a useful choice.  
           [0012]    Accordingly in a first aspect the present invention consists in a system capable of being used for oral delivery of gases pressurized above ambient to a user comprising: a mouthpiece; a breathing tube; and decoupling means for connecting said mouthpiece to said breathing tube, said decoupling means comprising a connection tube being formed of a material which is more flexible than the material of which said breathing tube is formed.  
           [0013]    In a second aspect the present invention consists in a mouthpiece comprising: a generally rectangularly-shaped vestibular shield having an inner surface and an outer surface, said vestibular shield having a predetermined height which will overlap a user&#39;s teeth and gums when positioned in the mouth vestibule of a user, said vestibular shield having a central portion which will extend over a user&#39;s front teeth and gums when said central portion of said vestibular shield is positioned between the lips and the teeth of the user, and outer portions extending from said central portion which extend along and overlap at least a portion of the user&#39;s back teeth and gums when said outer portions of said vestibular shield are positioned between the cheeks and the teeth of the user; and gases passageway means extending from said outer surface of said vestibular shield to said inner surface of said vestibular shield for allowing the passage of said gases through said mouthpiece.  
           [0014]    In a third aspect the present invention consists in a mouthpiece comprising:  
           [0015]    a vestibular shield having an inner surface and an outer surface, said vestibular shield having a predetermined height which will overlap a user&#39;s teeth and gums when positioned in the mouth vestibule of a user;  
           [0016]    gases passageway means extending from said outer surface of said vestibular shield to said inner surface of said vestibular shield for allowing the passage of said gases through said mouthpiece; and  
           [0017]    extra-oral sealing means associated with said gases passageway which may be adjusted into one of two configurations, a first condition when said mouthpiece is inserted into a user&#39;s mouth being substantially unengaged with a user&#39;s face, and a second condition when correctly positioned in a user&#39;s mouth being substantially engaged with a user&#39;s face and under compression thereupon.  
           [0018]    In a fourth aspect in a first aspect the present invention consists in a system capable of being used for oral delivery of gases pressurized above ambient to a user comprising:  
           [0019]    gases supply means,  
           [0020]    a gases passageway in fluid communication with said gases supply means, and  
           [0021]    a mouthpiece in fluid communication with said gases passageway including an intra-oral sealing means and an extra-oral sealing means.  
           [0022]    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.  
           [0023]    The invention consists in the foregoing and also envisages constructions of which the following gives examples. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]    One preferred form of the present invention will now be described with reference to the accompanying drawings in which;  
         [0025]    [0025]FIG. 1 is a side elevational view of the system according to the present invention as being used by a patient,  
         [0026]    [0026]FIG. 2 is a perspective view from above of a mouthpiece according to the preferred embodiment of the present invention,  
         [0027]    [0027]FIG. 3 is a perspective view from one side and from an inward direction of the mouthpiece of FIG. 2,  
         [0028]    [0028]FIG. 4 is a cross-section of the mouthpiece of FIG. 2,  
         [0029]    [0029]FIG. 5 is a cross-sectional view of the mouthpiece of FIG. 2 and a user with the mouthpiece in place to demonstrate the location and positioning thereof in relation to the main features of the user&#39;s anatomy,  
         [0030]    [0030]FIG. 6 is a perspective view of the mouthpiece with the outer flap in place,  
         [0031]    [0031]FIG. 7 is a perspective view of the outer flap bent back,  
         [0032]    [0032]FIG. 8 is a cutaway view of the present invention with the outer flap in use,  
         [0033]    [0033]FIG. 9 is a perspective view of the outer flap including the ventilation apertures and moisture barrier, and  
         [0034]    [0034]FIG. 10 is a block diagram of a respiratory system according to the preferred embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0035]    While the invention may be susceptible to embodiment in different forms, there is shown in the drawings, and herein will be described in detail, specific embodiments with the understanding that the present disclosure is to be considered an exemplification of the principles of the invention, and is not intended to limit the invention to that as illustrated and described herein.  
         [0036]    The present invention provides a novel system for oral delivery of gases pressurised above ambient to a user and is especially suited for use in the oral delivery of air in continuous positive airway pressure (CPAP) treatments of sleeping disorders such as sleep apnoea. As shown in FIG. 1, the system includes a mouthpiece  1  which is connected by a connection  40  to a breathing circuit  41 .  
         [0037]    A preferred embodiment of the present invention is illustrated in FIGS.  2  to  5 . In this embodiment, the mouthpiece  50  includes a vestibular shield  2  being a generally flat and generally rectangularly-shaped member in front elevation having a curved profile that reflects the curvature of a user&#39;s jaw and in turn the curvature of the labial vestibule region. A gases passageway extends through the vestibular shield from an inlet  51  to an outlet  52  in much the same way as with the earlier embodiments. In the preferred embodiment the inlet  51  is provided by a flattened oval-shaped connector  53 . The outlet  52  has an even more laterally extended flattened oval shape  54 . The major differences between the mouthpiece  50  and the embodiments described above are provided on the inner face of the vestibular shield. Most prominently, the mouthpiece  50  includes a tongue depressor  55  extending from the inner face of the vestibular shield  2 . The operation of the tongue depressor will be described further on with reference to FIG. 5. The tongue depressor includes a vertical stiffening flange  56  centrally located on its upper surface and extending from the gases outlet  52 . In use gases flow easily around the stiffening flange  56  effectively bifurcating the gases outlet  52 . The tongue depressor  55  further includes a pair of vertically extending spacers  57  which in use may abut against the roof of the wearer&#39;s mouth and ensure that the tongue cannot completely block the air passageway. In the mouthpiece  50  the sealing effect of the vestibular shield  2  against the lips of the user is enhanced by providing teeth abutments of significantly increased thickness than the raised area  20  of the earlier embodiments. In particular, an upper teeth abutment  58  and a lower teeth abutment  59  are provided, with the lower teeth abutment  59  protruding further from the inner face of the vestibular shield  2  than the upper teeth abutment  58 . This difference serves to match the typical over-bite of most users. The abutments  58  and  59  are not required to be wider than the gases outlet  52 .  
         [0038]    A notch  60  is provided centrally in the upper edge of the vestibular shield  2  to accommodate the upper frenal attachment. A slight bead  61  is provided around the edge of the vestibular shield  2  for user comfort, with the vestibular shield  2  otherwise being very thin for additional suppleness.  
         [0039]    Referring particularly to FIG. 4, in its preferred form the mouthpiece  50  is preferably formed by over-moulding a soft and supple material part  70  over a stiffer material part  67 . These can generally be termed the shield part and the passageway-forming insert. The passageway-forming insert preferably includes a pair of upper and lower vertical flanges  63  and  64  to fully engage within the supple material. The passageway-forming insert  67  includes the vertically extending stiffening flange  56  of the tongue depressor  55 , together with a curved planar portion  71  forming the backbone of the tongue depressor  55 . The vertically extending spacers  57  are of the soft and supple material and are part of the over-moulding  70 , as are the upper and lower teeth abutments  58  and  59 .  
         [0040]    Referring now to FIG. 5, use of the mouthpiece according to FIGS.  2  to  4  is depicted. With the present mouthpiece  50 , the upper and lower lips  5 ,  6  are further distended by the abutment action of the abutments  75 ,  76  against the upper and lower teeth  7 ,  8  respectively, thus forming a seal of greater pressure between the lips  5 ,  6  and the upper and lower portions respectively of the vestibular shield  2 . A lower face  77  of the tongue depressor  55  impinges if necessary on the upper surface  72  of the tongue  25  and retains the tongue in the lower portion of the mouth. This ensures a clear gases outlet  52  from the gases passageway through the vestibular shield. The vertically extending spacers  57 , if forced by pressure from the tongue, will engage against the roof of the user&#39;s mouth and maintain a clear air passageway. This stops the sleeping patient unconsciously blocking the oral passageway and reverting to nasal breathing.  
         [0041]    Attention is now directed to FIG. 1. It has been found that an additional factor in the effectiveness of any mouthpiece, including mouthpiece  1 , is the manner in which the mouthpiece is connected to the breathing circuit  41 . The weight of the breathing circuit  41 , and any attempted movement of one other of the breathing circuit  41  and the mouthpiece  1  relative to the other, is one of the largest influences tending to dislodge a mouthpiece  1  from the mouth of a user. It must be noted that the mouthpiece  1  must remain in position and maintain a seal during all sleep, when the user has no muscle tone.  
         [0042]    The connection  40  as provided in the present invention between the breathing circuit  41  and the mouthpiece  1  decouples the mouthpiece  1  from the breathing circuit  41 . As a result, the connection  40  is effective in reducing the forces placed on the mouthpiece  1  by the breathing circuit  41  when the user moves around during sleep. In the preferred sleeping position, the breathing circuit  41  is laid across the chest  43  of the user, and may be secured to the user&#39;s bed clothes or sleeping garments. The breathing circuit  41  is preferably laid on the chest of the user to take the weight of the breathing circuit  41  off of the mouthpiece  1 .  
         [0043]    To connect between the gases outlet  14  which is vertical when the user is laying on his or her back and the breathing circuit  41  which is generally horizontal, an L-shaped elbow  45  is incorporated in the connection  40 . The elbow  45  may be incorporated in the mouthpiece  1 , however, it is preferred that the mouthpiece  1  be kept small to provide for easier cleaning. The elbow  45  is formed at a right angle and provides a positive pressure on the mouthpiece  1  to maintain the mouthpiece  1  in the user&#39;s mouth. The elbow  45  may include a swivel joint and may be disconnected from gaseous outlet  14 . The connection  40  further includes an extremely flexible connecting tube  46  provided between the elbow  45  and the breathing circuit  41 . The connecting tube  46  is preferably connected to the breathing circuit  41  by a swivel joint  48  for reasons described herein. The breathing circuit  41 , while flexible, will necessarily be stiff enough to maintain its integrity over comparatively long tuns, while the connecting tube  46 , being only a short length, for example  10  centimetres, merely has to span between the user&#39;s mouth and chest, and can thereby be made in a manner that would not be suitable for long runs. Furthermore, as a result of the short length of the connecting tube  46 , the connecting tube  46  does not need to incorporate significant insulation or heating capability. The connecting tube  46  may be formed from a thin plastic membrane supported over a helical or double helical or corrugated supporting ribs. In such a case, the support makes the connection tube  46  laterally flexible and resistant to torsion. The elbow swivel joint  45  allows for movement of the connection tube  46  relative to the mouthpiece  1 . The swivel joint  48  allows for movement of the connection tube  46  relative to the breathing circuit  41 . It is to be understood that one or both of the swivel joints  45 ,  48  could be eliminated, but the preferred embodiment includes swivel joint  48 .  
         [0044]    Referring now to FIG. 6 of the present invention is illustrated including an extra-oral sealing flap  100 . The flap  100  in its natural bias is tapered, the wide open end of which is shaped to conform to the facial contours around the outside of the mouth of a user. The narrow end joins to a cylindrical section, which is designed to slide over the inlet port  104  of the mouthpiece  102 . While this is one method of attachment the flap  100  might also be constructed as an integral part of the mouthpiece  102 . The flap  100  needs to be constructed of flexible material, therefore materials such as silicone rubber can be employed to fashion the flap.  
         [0045]    The outer flap  100  is seen in FIG. 7, in a bent back position. It will be appreciated that when the mouthpiece  102  is being inserted into the mouth of a user, the outer flap  100  is intended to be in this bent back position to aid insertion. Prior to insertion, the outer flap is bent back by simply pressing on its outer periphery  106 , until it snaps into the bent back position, in which it will stay unaided.  
         [0046]    In FIG. 8 we see the outer flap  100  in use with the mouthpiece  102  in the mouth  107  of a user  110 . Once correctly positioned in the mouth  106 , the outer flap  100  may be adjusted into its operational position by pressing on its outer periphery  106  until it snaps back to press against the outside of the mouth  108 . Due to the relative position of the vestibular shield  112  and the outer flap  100 , the outer flap  100  is unable to fully reach its natural bias and thereby inflicts a compressive force on the outside of the mouth  108 .  
         [0047]    It will be appreciated that as well as providing a substantially airtight seal the addition of the outer flap provides enough compressive force on the mouth to keep the mouthpiece and conduit in place without the need for straps. This allows the administering of CPAP therapy to be considerably less obtrusive than traditional methods.  
         [0048]    In a further additional improvement shown in FIG. 9, the outer flap  300  is shown in perspective. Included are ventilation apertures  302 ,  303  either side of the gases port  304 , which are surrounded by a ridge  306  acting as a moisture barrier. The apertures  302 , 303  are provided such that any excess moisture leaking from the mouth will migrate to the apertures where they may evaporate. Small vents in the conduit may be used to direct small amounts of pressurised gas at the apertures to aid evaporation. The ridge  306  is included to ensure that no moisture migrates further into the sealing region  308 , as this would be detrimental to the sealing properties of the flap.  
         [0049]    A typical respiratory humidification circuit such as might employ the present invention is shown diagrammatically in FIG. 10, and includes the respirator  230 , humidifier  231 , and the associated respiratory breathing tubes  233  and  234 . A patient  236  under treatment is shown, with the present invention  237 , located in the mouth of the patient  236 .  
         [0050]    From the above it can be seen that the present invention provides a system including mouthpiece  1  for oral delivery of CPAP treatment which at once is low cost and effective. Unlike other appliances the mouthpiece  1  used in the present invention does not require custom orthodontic fitting as the mouthpiece  1  does not rely on accurate alignment with the user&#39;s teeth or the user&#39;s palate to provide location and retention within the user&#39;s mouth, but instead resides in the vestibule between the teeth and lips and the teeth and cheeks, and the lateral and vertical extension of the vestibular shield  2  requires that the user&#39;s lips be actively manipulated for the vestibular shield  2  to be removed. Furthermore the improved connection  40  to the breathing circuit  41  reduces the forces which tend to pull at the mouthpiece  1 . With the addition of the extra-oral flap  100 , the mouthpiece and associated tubing is held securely in place without the need for external strapping, and an effective seal is created around the users mouth.