Abstract:
The present invention is a system for stiffening a portion of the perimeter of a respiratory mask that has a formable element disposed about its perimeter, thereby making the respiratory mask more comfortable to wear.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of U.S. Provisional Application Ser. No. 60/741,304 filed Dec. 1, 2005, which is incorporated herein by reference, and is a continuation-in-part of U.S. Utility patent application Ser. No. 09/979,972 filed Nov. 28, 2001, now U.S. Pat. No. 7,210,481, issued May 1, 2007. 
    
    
     TECHNICAL FIELD 
     This invention relates to a respiratory mask used to supply a breathable gas to a patient. More specifically, it relates to a better means to conform such a mask, whether it is a nasal or full-face respiratory mask (hereinafter, collectively, “masks”), to the portions of a patient&#39;s face that the mask contacts. 
     BACKGROUND OF THE INVENTION 
     A number of relatively common breathing disorders are treated by delivery of pressurized, breathable gas to a patient&#39;s airway. This is customarily done through the use of a mask. A mask is normally held in place over a patient&#39;s nose or face by one or more straps. The straps encircle the patient&#39;s head and are adjusted to create a gas tight seal between the mask and the patient&#39;s face. For example, as shown in  FIG. 1 , a nasal mask  10  includes a shell  12 , forming a chamber with a seal  18 . The seal  18  contacts the wearer&#39;s face forming the gas tight seal. 
     The patient&#39;s nasal area and face are complexly contoured and differ from patient to patient. Thus, during extended use, the mask may move relative to the patient&#39;s nose or face breaking the gas tight seal or becoming uncomfortable. The customary response is for the patient to tighten the mask&#39;s straps, which may cause the mask to push too strongly on the soft tissue surrounding the patient&#39;s nose or on the patient&#39;s face. 
       FIG. 2  shows an example of how this problem was addressed in the prior art. As is described in more detail in U.S. patent application Ser. No. 09/979,972 filed Nov. 28, 2001, the constructed of a compliant and resilient material. Disposed along the perimeter  24 , and only the perimeter  24  of the shell is a formable element  26 . The formable element may be a wire made for a relatively soft metal such as aluminum or copper or other materials known to those skilled in the art. The formable element may be affixed to the surface of the shell or molded within the shell. 
     The formable element  26  can be constructed from any material that is formable and is capable of retaining the shape into which it is formed against the force of, for example, the resilient shell  22  trying to regain its memory shape. The combination of the compliant and resilient shell  22  and the formable element  26 , having sufficient rigidity to hold the shell  22  in a selected configuration, produces a “custom-fit” as desired by a particular user. Because the shell  22  is compliant, the perimeter and overall configuration of the shell  22  can be reformed repeatedly, as necessary, by a particular user. 
     In use, this mask, as shown in  FIG. 3 , tends to crease along a midline C running from the point  32  at which the mask contacts the bridge of the patient&#39;s nose to the point  33  at which the mask contacts the patient&#39;s face in the middle of the patient&#39;s chin. This crease causes the mask to become uncomfortable and causes the gas tight seal to be broken. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a respiratory mask that is more comfortable to wear and conforms better to a wearer&#39;s face. It is a system for stiffening one or more portions of a formable element disposed around the perimeter of the respiratory mask. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features and advantages of the present invention will be better understood by reading the following detailed description, taken together with the drawings wherein preferred embodiments are shown as follows: 
         FIG. 1  shows a nasal mask of the prior art in use; 
         FIG. 2  shows a schematic cross section of a full-face mask of the prior art; 
         FIG. 3  shows a schematic perspective view of a full-face mask of the prior art; 
         FIG. 4  shows a schematic perspective view of a preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention provides a system for stiffening, as described in more detail herein, a portion of the perimeter of a mask that has a formable element disposed about its perimeter. Referring to  FIG. 4 , one preferred embodiment of a full face mask  41  has a shell  42  constructed of a compliant and resilient material. A formable element  44  is disposed along the perimeter, and only the perimeter, of the shell  42 . The formable element  44  can be affixed to the surface of the shell  42  but is molded within the shell  42  here. A portion  45  of the formable element  44  running along the wearer&#39;s chin from  46  to  47  is stiffened. It is stiffened in this preferred embodiment by molding a polycarbonate sleeve  48  over the portion  45  of the formable element  44  before the formable element  44 , and polycarbonate sleeve  48 , are molded in the shell  42 . This causes the portion  45  of the formable element  44  to become more difficult to bend but not to be rigid, i.e., to be stiffened, compared to the remainder of the formable element  44 . The shell  42  of the mask  41  will not crease along the mid-line D running from point  50  at which the mask contacts the bridge of the patient&#39;s nose to point  52  at which the mask contacts the patient&#39;s face in the middle of the patient&#39;s chin as prior art masks might. In other preferred embodiments, one or more other portions of the formable element  44  may be stiffened to eliminate creasing or bending in such other portions. 
     It should be noted that there are a number of means known to those skilled in the art to stiffen a portion of the formable element  42 . A polycarbonate overmold is one of the least costly and most esthetically attractive. It should also be noted that the portion  45  of the formable element  44  that is stiffened should have some “give” in it. If it is made rigid, the formable element  44  tends to fail at points  46  and  47 . 
     The formable element  44  can be constructed from any suitable material that is malleable and is capable of retaining the shape into which it is formed against the force of, for example, the compliant shell  42  trying to regain its memory shape. The combination of the compliant shell  42 , malleable element  44  and stiffener (e.g.,  48 ) produces sufficient rigidity to hold the shell  42  in a selected “custom-fit” configuration, formed by a particular user or wearer. Because the shell  42  is compliant, the perimeter and overall configuration of an opening of the shell can be reformed repeatedly, as necessary, by the user or wearer of mask  41 . 
     While the principles of the invention have been described herein, it is to be understood by those skilled in the art that this description is made only by way of example and not as a limitation as to the scope of the invention. Other embodiments are contemplated within the scope of the present invention in addition to the exemplary embodiments shown and described herein. Modifications and substitutions by one of ordinary skill in the art are considered to be within the scope of the present invention.