Abstract:
A respiratory mask comprises a sealing flange connected to a mask body by a sinusoidal shaped cushioning member. The cushioning member resiliently compresses when the sealing flange is pressed against the face of a wearer to ensure an airtight seal between the sealing flange and the face of the wearer. The cushioning member functions as a spring, compressing to allow the sealing member to better conform to the face of the wearer but resiliently urging the sealing flange outward against the face of the wearer to prevent leaks.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a Continuation-in-Part of U.S. Design application Ser. No. 29/278,067 entitled RESPIRATORY MASK, filed Mar. 19, 2007. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to face masks for use in delivering respiratory gasses to a patient under positive pressure including such masks for use in treating sleep apnea or for other conditions requiring non-invasive positive pressure ventilation. 
     2. Background 
     The most effective and frequent therapy for obstructive sleep apnea is application of continuous positive airway pressure (CPAP). For such therapy, a patient is fitted with a tight fitting mask connected through an airway to a blower which supplies air to the patient&#39;s nasal passages or the nasal passages and mouth at a slight positive pressure. The application of the slight positive pressure is immediately effective in reversing the airway obstructions associated with obstructive sleep apnea. Although the therapeutic results of nasal CPAP are often dramatic and immediate, it is only effective when used properly and on a regular basis. Failure to apply nasal CPAP for even a single night results in recurrence of hypersomnolence the next day resulting from sleep apnea. 
     Problems associated with wearing existing masks or positive airway pressure delivery systems during periods of attempted sleep are sufficient to deter many patients from continuing CPAP therapy. Some problems include excessive noise and irritation resulting from leaks around improperly fitting masks or general discomfort caused by the design of the mask or the CPAP delivery system. Leakage of air between the mask and the face often allows air to blow on the eyes which wakes the patient and/or substantially irritates the eyes. 
     Most respiratory masks have integrally formed seals in the form of flexible or pliable flanges, cushions, pillows or the like extending around their outer periphery to form a seal between the mask and the face of the wearer. See for example the masks shown and described in U.S. Pat. Nos. 5,265,595 and 6,192,886. The seals are designed to prevent air from leaking through the interface between the mask and the wearer&#39;s face. However, patient movement and variations in the contours of different wearers&#39; faces make it difficult to maintain a complete seal with existing face masks. 
     There remains a need for a respiratory mask for supplying gas to a patient under pressure which incorporates a seal which readily conforms to varying contours of wearer&#39;s to prevent leaks. 
     SUMMARY OF THE INVENTION 
     In order to provide a respiratory mask with better sealing capabilities a sealing flange is connected to a mask body by a cushioning member which in a preferred embodiment is S-shaped. The S-shaped cushioning member resiliently compresses when the sealing flange is pressed against the face of a wearer to ensure an airtight seal between the sealing flange and the face of the wearer. 
     The mask body is generally cup shaped forming a mask chamber or cavity the outer periphery of which is generally circumscribed or defined by a peripheral edge that encircles the nose and mouth of a wearer when the mask body is positioned over the nose and mouth of the wearer. The S-shaped cushioning member includes a first arc which curves inward toward the mask chamber and a second arc which curves outward relative to the first arc and away from the mask chamber to form the s-shape of the S-shaped cushioning member. The S-shaped cushioning member generally functions as a spring, compressing to allow the sealing member to better conform to the face of the wearer but resiliently urging the sealing flange outward against the face of the wearer to prevent leaks. 
     The sealing flange preferably includes at least an inwardly extending sealing flange and may also include an outwardly extending sealing flange. Positive pressure air delivered into the mask chamber from an inlet in the front of the mask also acts on the inwardly extending sealing flange to urge the flange against the face of the wearer. Resilient ribs are formed in second arc of the S-shaped cushioning member and help resist compression of the second arc. Portions of the ribs also preferably engage the outer surface of the outwardly extending sealing flange to biasingly urge the outwardly extending sealing flange against the face of the wearer. 
     The mask body, S-shaped cushion, sealing flange assembly and ribs are preferably integrally formed from silicone or other like material that is flexible and resilient and which does not cause substantial skin irritation to the wearer. Rigid plastic supports are mounted on the outer surface of the mask body to provide rigidity to the respiratory mask and to resist excessive outward expansion of the mask body due to the internal pressure exerted on the mask body by the pressurized air directed therein. A first support extends across the portion of the mask extending across the bridge of a wearer&#39;s nose. A second support extends across the portion of the mask extending across the wearer&#39;s chin. The first and second supports also extend on opposite sides of the mask inlet. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partially schematic, perspective view of a respiratory mask with an improved sealing assembly shown secured to the face of a wearer. 
         FIG. 2  is a rear view of the respiratory mask. 
         FIG. 3  is an exploded and fragmentary cross-sectional view of the respiratory mask taken along line  3 - 3  of  FIG. 2 . 
         FIG. 4  is a fragmentary cross-sectional view of the respiratory mask similar to  FIG. 3  showing the mask, positioned on the face of a wearer. 
         FIG. 5  is a cross-sectional view of the respiratory mask taken along line  5 - 5  of  FIG. 2 . 
         FIG. 6  is a cross-sectional view of the respiratory mask taken along line  6 - 6  of  FIG. 2 . 
         FIG. 7  is an enlarged perspective view of an upper brace of the respiratory mask. 
         FIG. 8  is an enlarged perspective view of a lower brace of the respiratory mask. 
         FIG. 9  is an enlarged and fragmentary cross-sectional view taken generally along line  9 - 9  of  FIG. 1 . 
         FIG. 10  is an enlarged and fragmentary cross-sectional view taken generally along line  10 - 10  of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. The drawings constitute a part of this specification and include exemplary embodiments of the present invention and illustrate various objects and features thereof. 
     Certain terminology will be used in the following description for convenience in reference only and will not be limiting. For example, the words “upwardly,” “downwardly,” “rightwardly,” and “leftwardly” will refer to directions in the drawings to which reference is made. The words “inwardly” and “outwardly” will refer to directions toward and away from, respectively, the geometric center of the embodiment being described and designated parts thereof. Said terminology will include the words specifically mentioned, derivatives thereof and words of a similar import. 
     Referring to the drawings in more detail, the reference number  1  generally designates a respiratory mask with a mask body  2  and an improved seal or sealing assembly  3 . The mask body  2  and sealing assembly  3  are preferably constructed of silicone or other rubber-like or elastomeric material that is flexible and yet resilient and that does not cause substantial skin irritation to the user. For example it is foreseen that the mask body  2  and sealing flange assembly  3  could be formed from a thermoplastic elastomer, latex or other rubber-like materials in addition to the preferred silicone rubber. The mask body  2  is generally cup shaped and formed by a wall  7  having an inner surface  8 , an outer surface  9  and a peripheral margin, edge or boundary  10 . As best seen in  FIGS. 3 and 4 , the mask body  2  forms an internal chamber or cavity  11  for receiving the nose and mouth of a wearer through the rear open side of the mask body  2 . The seal  3  includes a seal cushion or sealing cushion  14  and a sealing flange assembly  15 . The seal cushion  14  is connected to and extends from the mask body  2  generally along the peripheral margin or edge  10  of the mask body  2  and the sealing flange assembly  15  is connected to the distal end of the seal cushion  14 . The seal cushion  14  may also be referred to as a spring or a spring cushion and is formed from flexible and resilient material to both urge or bias the sealing flange assembly  15  against the wearer&#39;s face and to allow the sealing flange assembly  15  to conform to the contours or shape of the wearer&#39;s face. The seal cushion  14  is preferably formed in the shape of a compound curve, which includes at least two arc segments to form an s-shape or sinusoidal shape. 
     The mask  1  is held on a wearer&#39;s face by mask securing means, which in the illustrated embodiment comprises a flexible skull cap or harness  18 , adjustable securement straps  19  and strap fasteners  20  which connect to rigid braces  21  and  22  which are mounted on the outer surface  9  of the mask body  2 . The braces  21  and  22  are relatively rigid and may be formed from a rigid plastic such as a polycarbonate or acrylic plastic. An airflow tubing assembly  25  is connected to the mask body  2  in line with an airflow port or opening  26  formed in the mask body  2  at a position selected to align with the mouth of a wearer of the mask  1 . Positive pressure air is generally directed into the mask cavity  11  through the airflow tubing assembly  25  and port  26 . 
     Referring again to  FIGS. 3 and 4 , the mask body  2  is configured to receive and cover the nose and mouth of a wearer within the internal mask cavity  11 . The mask body  2  is sized and configured such that when the mask is positioned against the face of the wearer, the peripheral margin  10  generally extends, across the bridge of the nose, down the sides of the nose, downward across the cheeks of the wearer on opposite sides of the mouth and then underneath the chin of the wearer. The seal cushion  14  is formed on the mask body  2  generally extending from the peripheral margin  10  thereof and continuously around the mask body  2 . 
     The seal cushion  14 , with the attached sealing flange assembly  3 , extends from the peripheral margin  10  of the mask along the portion adapted to be positioned to extend across the bridge of the nose, down the sides of the nose and downward across the cheeks on either side of the mouth. Instead of following the portion of the peripheral margin  10  adapted to extend under the chin of the wearer, the seal cushion  14 , with the attached sealing flange assembly  3 , extends across that portion of the inner surface  8  of the mask body  2  that is adapted to be positioned across and in front of the wearer&#39;s chin. The sealing cushion  14  is configured and oriented such that the sealing flange assembly  3  is oriented to generally face rearward so that the sealing flange assembly  3  can be pressed rearward against the wearer&#39;s face to facilitate formation of a seal between the flange assembly  3  and the wearer&#39;s face. 
     The sealing cushion  14  is preferably formed as a compound curve having at least a first arc or first section  31  that curves inward from the mask body  2  generally toward the center of the cavity  11  formed in the mask body  2 , and a second section or second arc  32  that extends from and curves in an opposite direction from the first are  31  and generally back outward away from the mask cavity  11 . As seen in  FIGS. 5 and 6 , portions of the sealing cushion  14  include a third section or third arc  33 , namely all but that portion of the sealing cushion  14  that is adapted to be positioned across the chin of the wearer. The third arc  33  curves in a direction opposite of the curve of the second arc  32 . Each of the arcs  31 ,  32  and  33  is preferably progressively shorter in length and radius. The sealing cushion  14  may also be described as being generally sinusoidal in shape or as forming a sinusoidal spring. 
     A distal end  34  of the sealing cushion  14 , whether at the end of the third arc  33  or the second arc  32 , generally faces or projects rearward relative to the front of the mask body  1 . The distal end  34  of the sealing cushion  14  is oriented to project toward the face of the wearer against which the mask  1  is to be positioned. 
     The sealing flange assembly  15  is integrally formed on the distal end  34  of the sealing cushion  14  and preferably includes an inner sealing flange  37  and an outer sealing flange  38 . The inner and outer sealing flanges  37  and  38  preferably extend continuously around the mask body  2  along the sealing cushion  14 . The inner sealing flange  37  projects inward toward the interior of the mask body  2  or the mask body cavity  11 . The outer sealing flange  38  projects outward and away from the interior of the mask body  2 . Along the portion of the sealing assembly  3  adapted to be positioned against the cheeks and chin of the mask wearer, both sealing flanges  37  and  38  project generally transverse to the distal end  33  of the sealing cushion  14  and then angle or curve slightly rearward relative to the front of the mask body  2 . In a preferred embodiment, the portion of the sealing flanges  37  and  38  adapted to be positioned against the cheeks and chin of the wearer generally present a concave surface, curving toward the face of the wearer. 
     Along the portion of the sealing assembly  3  adapted to be positioned against the sides of and across the bridge of the wearer&#39;s nose, the inner sealing flange  37  initially projects rearward relative to the front of the mask body  2  and then curves around and projects into the internal cavity  11  and toward the front of the mask body  2 . The inner sealing flange  37  is sized to be relatively wide along the portion of the sealing assembly  3  intended to extend over the nose with a slit  41  extending between the opposed inner sealing flanges along this portion to receive the wearer&#39;s nose. The portions of the inner sealing flange  37  adapted to extend over or against the nose of the wearer may be referred to as nose flaps  42  and  43 . 
     The inner sealing flange  37  is formed relatively thin, with a thickness of approximately 0.018 to 0.20 inches near the inner edge thereof. The thin construction of the inner sealing flange  38  allows it to more readily conform to the unique contours of the specific wearer&#39;s face. In addition when pressurized air is pumped into the mask cavity  11 , the pressurized air acts against the inner surface of the inner sealing flange  37  to urge the inner sealing flange  37  against the face of the wearer to improve the seal. The large size of the nose flaps  42  and  43  helps ensure a proper seal around the wearer&#39;s nose regardless of its size or shape, which can vary significantly. 
     Elastic ribs  44  are formed on the sealing assembly  3  on the outside of the seal cushion  14  and preferably at least inside the second arc  32  to provide some resistance to compression of the second arc  32  and the sealing cushion  14 . For most of the ribs  44 , a first end of the rib  44  is connected to the outer surface of the first arc  31  and a second end of the rib is connected to the outer surface of the outer sealing flange  38  to provide resistance to compression of the outer sealing flange  38  relative to the first arc  31  and the mask body  2 . In the embodiment shown, elastic ribs  44  extend along the length of the seal cushion  14  except for that portion adapted to be positioned across the chin of the wearer. 
     The seal cushion  14  gradually tapers or reduces in thickness from the peripheral margin  10  of the mask body to the distal end  34  of the seal cushion  14 . The distal end  34  is preferably only half or one third as thick as the peripheral margin  10  of the mask body  2 . The mask body  2  generally needs sufficient thickness to prevent excessive distortion of the shape or rupturing of the mask body  2 . However, pressing of the relatively thick-walled and rigid peripheral margin  10  of the mask body  2  against a wearer&#39;s face would rapidly cause uncomfortable wearing and possibly necrosis of the patient&#39;s skin, particularly across the bridge of the wearer&#39;s nose. 
     The seal cushion  14 , disclosed herein, generally positions the sealing flange assembly  15  rearward and slightly inward from the peripheral margin  10  of the mask body  2 . As the mask  1  is pressed or drawn against a wearer&#39;s face, the relatively thin walled seal cushion  14  compresses or gives to conform to the unique contours of the wearer&#39;s face. The seal cushion  14  has sufficient resiliency to resist complete compression of the seal cushion  14  to prevent the sealing flange assembly  15  from bottoming out relative to the peripheral margin  10  of the mask body  2 . The forces used to draw the mask against the wearer&#39;s face are therefore spread out over the larger surface area of the sealing flange assembly  15  and are not focused along the more rigid peripheral margin  10  of the mask body  2 , thereby reducing the development of pressure sores or the like. 
     The portion of the mask body  2  adapted to extend under the chin of a wearer and past the sealing assembly  3  may be referred to as a chin cup  48 . Because the chin cup  48  is formed integrally with the mask body  2  and the sealing assembly  3 , when a user lowers his or her jaw, extension or stretching of the chin cup  48  simultaneously pulls the sealing assembly  3  positioned across the chin downward with the chin to maintain the proper sealing arrangement. 
     As discussed above, the airflow opening or port  26  extends through the mask so as to flow communicate with the internal chamber or cavity  11 . The opening  26  is generally positioned to be aligned with the mouth of a user when the mask  5  is abuttingly positioned against the face of a user. The opening  26  is further sized so as to generally encircle the opening formed by the mouth of the user when the mouth is used for breathing during ventilatory measurement and analysis procedures. The opening  26  is defined by a grooved circular shoulder  51 , extending through the face mask  1  from the inner surface  8  to the outer surface  9 . A rim receiving groove  52  extends into the mask body  2  along the grooved circular shoulder  51 . 
     The airflow tubing assembly  25  is connected to the face mask  1  at the circular opening  26  by an annular connecting member  55 . The annular connecting member  55  includes a connecting rim  56 . The airflow tubing assembly  25  may be of the type including a valve to control the direction of flow of inhalation and exhalation gasses through different openings or passageways. Pressurized air can be supplied to the mask cavity  11  from a source of pressurize air  57  (shown schematically in  FIG. 1 ) through the airflow tubing assembly  25 . 
     Each of the upper and lower rigid braces  21  and  22  is connected to the face mask  1  by first and second pairs of flexible mounting buttons  59  and  60  respectively formed on the outer surface  9  of the mask body  2 . The buttons  59  and  60  are integrally formed of the same flexible material as the rest of the mask body  2  and each comprises a cylindrical post  63  and an enlarged cylindrical head  64 . 
     As best seen in  FIGS. 7 and 8 , each brace  21  and  22  is generally bowed inward to conform to the side to side contour of the mask body  2 . The upper brace  21  includes a relatively narrow central band  66  with enlarged mounting structure  67  formed on each end thereof. Lower brace  22  also includes a central band  71  with mounting structure  72  formed on each end thereof. The central band  66  of the upper brace  21  is positioned to extend across the portion of the mask body  2  covering the bridge of the wearer&#39;s nose. The central band  71  of the lower brace  22  is positioned to extend across the portion of the mask body  2  covering the wearer&#39;s chin. 
     A pair of button receiving holes  73  and  74  are formed in the mounting structures  67  and  72  respectively of each rigid brace  21  and  22 . Each of the holes  73  and  74  is preferably oblong with one axis longer than the diameter of the button head  64  and a second axis narrower than the button head  64  diameter. The gap between the head of each button  59  and  60  and the outer surface  9  of the mask body  2  is approximately equal to the thickness of the respective braces  21  and  22 . The heads  64  of each of the buttons  59  and  60  are pressed through the button receiving holes  73  and  74  to hold the braces  21  and  22  in place against the outer surface  9  of the mask body  2 . 
     First and second pairs of channel forming shoulders  79  and  80  are formed on the outer surface  9  of the mask body  2  above and below the opening  26  respectively. The central portion  66  and  71  of rigid braces  21  and  22  respectively are secured between the first and second pairs of channel forming shoulders  79  and  80  respectively to prevent reduce movement of the braces  21  and  22  relative to the mask body  2 . 
     Recesses or indentations  84  may be formed in the mask body  2  on opposite sides of the airflow opening or port  26 . The indentations  84  are preferably sized slightly wider than a wearer&#39;s fingers so that the thumb and an opposed finger of the wearer may be positioned in the indentations  84  to facilitate grasping and handling of the mask body  2 . The recesses  84  also function to reduce the volume of the internal chamber or cavity  11  in the mask body  2 , reducing dead air space and enhancing the performance of the mask for most ventilation purposes. 
     Receivers  85  and  86  for the strap fasteners  20  are formed in each of the mounting structures of braces  21  and  22  respectively near the distal ends thereof such that at least one strap  19  may be connected to both ends of each brace  21  and  22 . Each of the strap fasteners  20  comprises a fastener base  88  with a post  89  having a cylindrical shaft  90  and an enlarged head  91  formed on a distal end thereof projecting outward from one side of the fastener base  88 . A slot  92  is formed in the base  88  through which a strap  19  may be threaded and folded over back onto itself and secured together with hook and loop type fasteners or the like for adjustably securing the strap  19  to the fastener  20 . A grip  93  may be formed on the fastener body  88  on a side opposite the post  89  to facilitate gripping and manipulation of the fastener  20 . 
     The fastener receivers  85  and  86  shown are generally keyhole type openings with a wide end  95  and a narrow end  96 . The wide end  95  is wider than the diameter of the post head  90  and the narrow end  96  is narrower than the diameter of the head  90  and slightly wider than the diameter of the post shaft  90  for receiving and frictionally retaining the shaft  90  therein. 
     The length of the straps  19  are adjustable to allow the wearer to draw the mask  1  against there face with sufficient force to ensure a proper seal is maintained by the sealing assembly  3 . The straps  19  and the cap  18  may be formed from elastic material to accommodate movement of the wearer&#39;s face and head. As discussed previously as the mask body  2  is drawn against the face of the wearer, the seal cushion  14  compresses and generally biases the sealing flange assembly  15  against the face of the wearer. 
     The rigid braces  21  and  22  help resist deformation of the mask body  2  due to the pressures exerted thereon by the pumping of pressurized air into the internal chamber  11  of the mask body  2 . By reinforcing the flexible mask body  2  with rigid braces  21  and  22  the thickness of the wall  7  forming the mask body can be reduced. The added rigidity supplied by braces  21  and  22  helps maintain the sealing assembly  3  in a preferred alignment with the face of the wearer to ensure a proper and complete seal. Without the braces, the mask body  2  would tend to expand outward under the pressure of the pressurized air pumped therein, increasing the risk that the seal between the wearer&#39;s face and the sealing assembly  3  will be broken. Any break in the seal will result in uncomfortable leaks which tend to tickle the wearer or create annoying noises. 
     Providing receivers for the securement strap fasteners  20  on the rigid braces  21  and  22  also reduces the forces acting on the flexible mask body  2  to help the mask body  2  retain its shape. Mounting the strap fasteners directly to the flexible mask body  2  would result in the tensioning forces exerted through the strap fastener to be concentrated to that portion of the mask where the strap fasteners are connected. By connecting the strap fasteners  20  to the rigid braces  21  and  22 , the forces exerted by the strap fasteners can be more evenly distributed across the mask body  2 . 
     It is to be understood that while certain forms of the present invention have been illustrated and described herein, it is not to be limited to the specific forms or arrangement of parts described and shown. For example, it is to be understood that with respect to the strap fasteners  20 , the keyhole openings could be formed in each fastener base  78  and the mating posts  79  could be formed on and project outward from the rigid braces  21  and  22 . It is foreseen that the mask  1  could be utilized without the braces  21  and  22 . The location and positioning of the ribs  44  could be varied or the ribs  44  could be eliminated. The relative dimension and size of any of the components could be varied including the size of the inner and outer sealing flanges  37  and  38 . 
     As used in the claims, identification of an element with an indefinite article “a” or “an” or the phrase “at least one” is intended to cover any device assembly including one or more of the elements at issue. Similarly, references to first and second elements is not intended to limit the claims to such assemblies including only two of the elements, but rather is intended to cover two or more of the elements at issue. Only where limiting language such as “a single” or “only one” with reference to an element, is the language intended to be limited to one of the elements specified, or any other similarly limited number of elements.