Patent Publication Number: US-9844639-B2

Title: Patient interface device including a coating adhesive layer

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Divisional under 35 U.S.C. §120 of U.S. patent application Ser. No. 12/743,045, filed May 14, 2010, which claims priority under 35 U.S.C. §119(e) from provisional U.S. patent application No. 60/988,914, filed Nov. 19, 2007, the contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to patient interface devices, and in particular to a patient interface device, such as a mask or cannula, that includes one or more coating layers acting as an adhesive and, in certain applications, a sealant. 
     2. Description of the Related Art 
     A variety of respiratory masks are known which have a flexible seal that covers the areas surrounding the nose and/or mouth of a human user and that are designed to create a continuous seal against the user&#39;s face. Because of the sealing effect created, gases can be provided at a positive pressure within the mask for consumption by the user. The uses for such masks include high altitude breathing (aviation applications), swimming, mining, fire fighting and various medical diagnostic and therapeutic applications. 
     One requisite of many of these masks, particularly medical respiratory masks, is that they provide an effective seal against the user&#39;s face to prevent leakage of the gas being supplied. Commonly, in conventional 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 the mask continuously for hours or perhaps even days. In such situations, the user often will not tolerate the mask for long durations and therefore optimum therapeutic or diagnostic objectives will not be achieved, or will be achieved with great difficulty and considerable user discomfort. 
     Several types of respiratory masks for the types of applications mentioned above are known. Perhaps the most common type of mask incorporates a smooth sealing surface extending around the periphery of the mask and exhibiting a generally uniform, i.e., predetermined or fixed, seal surface contour that is intended to be effective to seal against the user&#39;s face when force is applied to the mask with the sealing surface in confronting engagement with the user&#39;s face. The sealing surface typically consists of an air or fluid filled cushion, or it may simply be a molded or formed surface of a resilient seal element made of an elastomer such as plastic, rubber, silicone, vinyl or foam. 
     Such masks have performed well when the fit is good between the contours of the seal surface and the corresponding contours of the user&#39;s face. This may occur, for example, if the contours of the user&#39;s face happen to match well with the predetermined contours of the seal. However, if the seal fit is not good, there will be gaps in the seal-to-face interface resulting in gas leaking from the mask at the gaps. Considerable force will be required to compress the seal member to close the gaps and attain a satisfactory seal in those areas where the gaps occur. Such force is undesirable because it produces high pressure points elsewhere on the face of the user where the mask seal contour is forcibly deformed against the face to conform to the user&#39;s facial contours. This will produce considerable user discomfort and possible skin irritation and breakdown anywhere the applied force exceeds the local perfusion pressure, which is the pressure that is sufficient to cut off surface blood flow. Ideally, contact forces should be limited between the mask and the user&#39;s face to avoid exceeding the local perfusion pressure, even at points where the mask seal must deform considerably. 
     The problem of seal contact force exceeding desirable limits is even more pronounced when the positive pressure of the gas being supplied is relatively high or is cyclical to relatively high levels. Because the mask seals by virtue of confronting contact between the mask seal and the user&#39;s face, the mask must be held against the face with a force sufficient to seal against leakage of the peak pressure of the supplied gas. Thus, for conventional masks, when the supply pressure is high, head straps or other mask restraints must be relatively tightly fastened. This produces high localized pressure on the face, not only in the zone of the mask seal, but at various locations along the extent of the retention straps as well. This, too, will result in discomfort for the user after only a brief time. Even in the absence of excessive localized pressure points, the tight mask and head straps may become uncomfortable, and user discomfort may well cause discontinued cooperation with the treatment regimen. Examples of respiratory masks possessing continuous cushion sealing characteristics of the type just described are provided in U.S. Pat. Nos. 2,254,854 and 2,931,356. 
     In addition, nasal cannulas are used in a variety of clinical situations such as oxygen delivery, gas sampling (e.g., carbon dioxide), and pressure measurement. Nasal cannulas and similar devices are generally retained in place by the tension resulting from looping the associated tubing or cable over the patient&#39;s ears, which often creates discomfort. Patient movement resulting from the discomfort may cause the nasal cannula to become dislodged. 
     There is thus room for improvement in the area of mask, cannulas, and similar patient interface devices. 
     BRIEF SUMMARY OF THE INVENTION 
     In one embodiment, the invention provides a patient interface device, such as a mask or nasal pillow, that includes at least one seal element and an adhesive layer provided on an outer surface of the at least one seal element. The adhesive layer is structured to temporarily bond to the skin of the user of the patient interface device and comprises a bonding agent having a residual extraction force of between about 50 grams and about 160 grams. The bonding agent may be a cross linked polymer gel, such as a silicone gel or a polyurethane gel. In one particular embodiment, the adhesive layer further includes a coating layer formed by co-curing the bonding agent with at least one layer of a primer material. The adhesive layer may comprise at least one generally annular strip, of uniform or varying width, and in particular may be a plurality of concentric generally annular strips. Furthermore, the adhesive layer may have a generally uniform height, or, alternatively, may have a varying height. In one particular embodiment, the adhesive layer comprises a plurality of deposits of the bonding agent provided on the outer surface of the at least one seal element. Such deposits may have similar or differing sizes, and may have similar or differing geometric shapes (such as circular, triangular or oblong shapes). 
     Another embodiment provides a patient interface device that includes a mask having a body, at least one seal element coupled to the body, a facial support having an engagement surface coupled to the body, and an adhesive layer provided on the engagement surface, the adhesive layer comprising a bonding agent having a residual extraction force of between about 50 grams and about 160 grams. This patient interface device may or may not also include an adhesive layer on a sealing element of the mask. 
     In another embodiment, a nasal cannula is provided that includes one or more nasal inserts for delivering a fluid to the nasal passageway of a user, at least one attachment panel, and an adhesive layer provided on the at least one attachment panel and being structured to temporarily bond to the skin of the user, the adhesive layer comprising a polymer gel such as a silicone gel or a polyurethane gel. The adhesive layer may further include a coating layer formed by co-curing the polymer gel with at least one layer of a primer material. In the preferred embodiment, the polymer gel has a residual extraction force of between about 50 grams and about 160 grams. In another particular embodiment, the nasal cannula includes a fluid delivery tube in fluid communication with the one or more nasal inserts. In this embodiment, the fluid delivery tube is inserted through one or more apertures provided in the at least one attachment panel, whereby the at least one attachment panel is free to move relative to the fluid delivery tube prior to being temporarily bonded to the skin of the user. In still another particular embodiment, the nasal cannula includes a first fluid delivery tube and a second fluid delivery tube in fluid communication with the one or more nasal inserts, wherein the at least one attachment panel comprises a first attachment panel and a second attachment panel connected to one another by a connecting strip, In this embodiment, the first fluid delivery tube is inserted through an aperture provided in the first attachment panel and the second fluid delivery tube is inserted through an aperture provided in the second attachment panel, whereby the first attachment panel is free to move relative to the first fluid delivery tube and the second attachment panel is free to move relative to the second fluid delivery tube. 
     In yet another embodiment, the invention provides a nasal cannula that includes one or more nasal inserts for delivering a fluid to the nasal passageway of a user, a fluid delivery barrel in fluid communication with the one or more nasal inserts, and an adhesive layer provided on one or more outer surfaces of the fluid delivery barrel and being structured to temporarily bond to the skin of the user, the adhesive layer comprising a polymer gel such as a silicone gel or a polyurethane gel. The adhesive layer may further include a coating layer formed by co-curing the polymer gel with at least one layer of a primer material. In the preferred embodiment, the polymer gel has a residual extraction force of between about 50 grams and about 160 grams. 
     These and other objects, features, and characteristics of the present invention, as well as the methods of operation and functions of the related elements of structure and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description given below, serve to explain the principles of the invention. As shown throughout the drawings, like reference numerals designate like or corresponding parts. 
         FIG. 1  is a front elevational view and  FIG. 2  is a cross sectional view of a respiratory mask according to an embodiment of the invention; 
         FIGS. 3 and 4  are front elevational views of a respiratory mask according to alternate embodiments of the invention; 
         FIGS. 5A, 5B and 5C  are schematic diagrams showing the adhesive layer of the present invention in the form of a pattern of deposits of a bonding agent on a sealing element; 
         FIGS. 6A through 6E  are schematic diagrams of various embodiments of an adhesive layer of the present invention; 
         FIGS. 7 and 8  are top plan and cross sectional views, respectively, of a patient interface device in the form of a nasal pillow according to another embodiment of the invention; 
         FIG. 9  is a front elevational view of a mask according to yet another embodiment of the invention; 
         FIGS. 10 and 11  are top plan views of forehead supports forming a part of a mask according to alternative embodiments; 
         FIG. 12  is an isometric view of a patient interface device in the form of a nasal cannula according to further embodiment of the invention; 
         FIG. 13  is a schematic diagram showing the patient interface device of  FIG. 12  in use; 
         FIG. 14A  is an isometric view of a patient interface device in the form of a nasal cannula according to an alternate further embodiment of the invention; 
         FIG. 14B  is an isometric view of a nasal cannula according to an alternative embodiment which is a variation of the nasal cannula shown in  FIG. 14A  wherein only a single fluid delivery tube is employed; 
         FIG. 15  is a schematic diagram showing the nasal cannula of  FIG. 14B  in use; 
         FIGS. 16A and 16B  are isometric views of a nasal cannula according to a further alternate embodiment of the present invention; 
         FIG. 17  is a schematic diagram showing the nasal cannula of  FIGS. 16A and 16B  in use; 
         FIG. 18  is an isometric view of a patient interface device in the form of a nasal cannula according to still a further embodiment of the invention; 
         FIG. 19  is an isometric view of a patient interface device in the form of a nasal cannula according to yet a further embodiment of the invention; and 
         FIG. 20  is a schematic diagram showing of a patient interface device in the form of a nasal cannula according to yet a further embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
     Directional phrases used herein, such as, for example and without limitation, top, bottom, left, right, upper, lower, front, back, and derivatives thereof, relate to the orientation of the elements shown in the drawings and are not limiting upon the claims unless expressly recited therein. 
     As employed herein, the term “patient interface device” refers to any suitable mechanism for transporting gas to and/or from the airway of a patient and expressly includes, but is not limited to, non-invasive patient interfaces such as masks (e.g., without limitation, masks including support elements such as forehead supports and cheek pads and full face masks such as the Total™ face mask sold by the assignee hereof), nasal cannulas, nasal masks (including tip of the nose masks such as the Simplicity™ and Comfort Lite™ masks sold by the assignee hereof), combination nasal/oral masks and nasal pillows. 
     As employed herein, the statement that two or more parts or components are “coupled” together shall mean that the parts are joined or operate together either directly or through one or more intermediate parts or components. 
     As employed herein, the term “number” shall mean one or more than one and the singular form of “a”, “an”, and “the” include plural referents unless the context clearly indicates otherwise. 
       FIG. 1  is a front elevational view and  FIG. 2  is a cross sectional view of a respiratory mask  10  according to an embodiment of the invention. The respiratory mask  10  includes a shell or body  12  having an open side  14  that defines a generally annular surface  16  to which is sealingly affixed a seal element  18 . The mask body  12  is preferably, although not necessarily, a generally rigid shell, whereas the seal element  18  is a flexible, resilient unitary member made of, for example, an elastomer such as plastic, rubber, silicone, vinyl or foam. 
     The mask body  12  also defines an opening  20  to which there is attached a fluid coupling device, such as a swivel conduit  21  ( FIG. 2 ), for carrying fluid, such as a breathing gas, between the chamber within the mask  10  and an external gas source (not shown), such as a blower or other suitable device. It is to be understood that the present invention contemplates a variety of different fluid coupling devices that could be attached, either permanently or selectively, to the opening  20  to carry fluid to or from the chamber defined by the mask  10 . 
     The mask  10  shown in  FIGS. 1 and 2  is a nasal mask that accommodates the nasal regions of the user&#39;s face. It is to be understood, however, that the present invention also contemplates other patient interface devices such as, without limitation, a full face or an oral/nasal mask that accommodates both the mouth and nose of a user or a total face mask that accommodates substantially the entire facial area of the patient. As is conventional, the mask body  12  also preferably includes fastening devices, such as tabs  25  or the like, that connect to suitable adjustable retention straps (not shown) for retaining the mask with respect to the user&#39;s face. Although two such devices are illustrated in  FIGS. 1 and 2  and are generally arrayed at selected corners of the mask  10 , it is to be understood that other configurations, arrangements, numbers (including none) and locations of fastening devices can be provided without deviating from the principles of the present invention. Although not illustrated, the present invention contemplates providing one or more exhaust ports or other venting mechanisms at a location or locations, such as in the seal element  18 , the mask body  12 , the conduit  21  or at a junction between these components, to exhaust gas expired by the user to atmosphere. 
     The seal element  18  includes a solid, yet highly resilient and self-sustaining compressible, generally annular member  27  comprising a peripheral wall portion  28  having a generally annular base or inner end  30  configured so as to substantially match the surface  16  of the mask body  12  to which it is attached. The peripheral wall portion  28  further establishes an outer end  32  generally opposite inner end  30 . The outer end  32  defines a generally annular contoured surface  34 . The contour of surface  34  is preformed to closely approximate the surface contour of a user&#39;s facial structure, especially in the areas of the bridge of the nose, the cheeks adjacent the nose, the space intermediate the nose and upper lip, and the intervening areas contiguous to these. It is to be understood that the contour of the surface  34  can have alternative configurations depending on the type of mask to which the seal element  18  is attached. For a full face mask, for example (not illustrated), the surface  34  may be contoured to accommodate the user&#39;s chin in lieu of the area intermediate the nose and upper lip. In either case, variation in the user&#39;s facial structure, especially in the area of the bridge of the nose, for example, makes considerable flexibility of the seal element  18  desirable to accommodate the many different facial contours likely to be encountered. 
     According to an aspect of the present invention, an adhesive layer  40  made of a bonding agent is provided on and bonded to the contoured surface  34  of the annular member  27  of the seal element  18 . The adhesive layer  40  has a level of stickiness that will cause it to temporarily bond to the skin of the user of the mask  10 , preferably without leaving a significant amount of residue when removed. The adhesive layer  40  will thus provide a bonding seal between the mask  10  and the user&#39;s skin so as to reduce and/or eliminate leaks. In addition, with the sealing bond provided by the adhesive layer  40 , the strapping forces (through the tabs  25  or the like) can be reduced. For example, a mask may need a smaller number of straps than would be needed without the adhesive layer  40 . In fact, in some applications (e.g., flow pressures of 8 cm H2O or less), the adhesive layer  40  may eliminate the need for strapping altogether. 
     In the preferred embodiment, the bonding agent of the adhesive layer  40  will have a residual extraction force of between about 50 grams and about 200 grams, and most preferably between about 50 grams and about 160 grams. As used herein, the term residual extraction force means the force required to pull a probe about 12.7 mm (about 0.5 inches) round from the subject material when the probe has been inserted to a depth of about 10 mm (about 0.3937 inches) in a container about 60 mm (about 2.362 inches) in diameter and about 45 mm (about 1.772 inches) deep that is filled with the subject material. In one particular embodiment, the bonding agent of the adhesive layer  40  is a cross linked polymer gel (most preferably with no plasticizer) such as, without limitation, a silicone gel or a polyurethane gel. As is known, a general purpose silicone gel typically has a residual extraction force of 8 to 15 grams. In one preferred embodiment, the bonding agent of the adhesive layer  40  is a silicone gel having a residual extraction force of about 160 grams, which is ten fold stickier than the general purpose silicone gel. 
     Due to the soft nature of the adhesive layer  40 , it is possible that in some applications, a small amount of the adhesive layer  40  may separate therefrom under physical rubbing and be left on the user&#39;s skin as a residual material. In order to avoid this phenomenon, the adhesive layer  40  in one particular embodiment may further include a coating layer formed by co-curing the bonding agent with layer of a primer material that will resist material separation. For example, and without limitation, in the case where the bonding agent of the adhesive layer  40  is a silicone gel, any non-gel based silicone, such as a soft RTV-2 material or an LSR (liquid silicone rubber) material can be used as the primer, and the case where the bonding agent of the adhesive layer  40  is a polyurethane gel, a solvent such as acetone can be used as the primer. 
     In the embodiment shown in  FIGS. 1 and 2 , the adhesive layer  40  is a single, generally annular strip having a generally uniform width provided on the contoured surface  34  of the annular member  27  of the seal element  18 . It is to be understood that this is meant to be exemplary only, and that many other configurations are possible for the adhesive layer  40 . For example, as shown in  FIG. 3 , the adhesive layer  40  may comprise two or more generally annular portions or strips (of generally uniform or varying widths), or as shown in  FIG. 4 , the adhesive layer  40  may comprise a non-annular layer (of a generally uniform or varying width), covering only a portion of the contoured surface  34  of the annular member  27  of the seal element  18 . In one particular embodiment, a generally annular relatively thin strip forming the adhesive layer  40  may be provided at the outer edge of the contoured surface  34  in order to provide effective sealing enhancement without making the entire contoured surface  34  sticky. Many other configurations are also possible. For example, and without limitation, as seen in  FIGS. 5A, 5B and 5C , the adhesive layer  40  may be in the form of a series or matrix or pattern (uniform or varying) of differently sized ( FIG. 5A ) or similarly sized ( FIGS. 5B and 5C ) generally circular, oblong and/or triangular deposits of the bonding agent. Other geometric shapes are also possible. 
     Furthermore, the height of the adhesive layer  40  (or portions thereof) can have various attributes for achieving different results. For example, as shown in  FIG. 6A , the height of the adhesive layer  40  can be generally uniform, resulting in a generally smooth surface that maximizes adhesion. A typical height may be on the order of about 0.010 inches (about 0.254 millimeters) to about 0.125 inches (about 3.175 millimeters), although other heights are possible and will depend on the particular application. Alternatively, as shown in  FIG. 6B , the height of the adhesive layer  40  can be varied over the area of the adhesive layer  40 , resulting in a surface that provides enhanced surface venting and makes the adhesive layer  40  easier to peel from the skin of the user. These latter attributes will also be provided by the configuration of the adhesive layer  40  shown in  FIG. 6C , which comprises a pattern of generally circular deposits (i.e., mounds) of the bonding agent. In addition, the contoured surface  34  is often designed to have uneven wall thickness to promote softness and different flexibilities. Therefore, depending on the desired results, the height of the adhesive layer  40  can vary with the thickness of the contoured surface  34 . For example, as shown in  FIG. 6D , the height of the adhesive layer  40  may increase while the thickness of the contoured surface  34  decreases. This will enhance the bonding even at thinner sections of the contoured surface  34  without changing the overall feel (softness) of the mask  10 . Furthermore, as shown in  FIG. 6E , the height of the adhesive layer  40  may increase while the thickness of the contoured surface  34  also increases. This will maintain a more flexible structure. 
       FIGS. 7 and 8  are top plan and cross sectional views, respectively, of a patient interface device in the form of a nasal pillow  42  according to another embodiment of the invention. The nasal pillow  42  includes first and second naris members  44 A and  44 B having top surfaces in the form of seal elements structured to engage the exterior surfaces of the nares of the nose of a user to deliver a fluid, such as air or oxygen, to the nasal passageway of the user. As seen in  FIGS. 7 and 8 , the top surface of each naris member  44 A,  44 B is provided with an adhesive layer  40  as described elsewhere herein. The adhesive layer  40  of each naris member  44 A,  44 B will thus provide a bonding seal between the nasal pillow  42  and the user&#39;s skin at the exterior surfaces of the nares. 
       FIG. 9  is a front elevational view of a mask  46  according to yet another embodiment of the invention. The mask  46  is similar to the mask  10 , and therefore, as seen in  FIG. 9 , includes a number of the same parts. The mask  46  further includes a forehead support  48  connected to and extending from the mask body  12  through a support arm  49 . The forehead support  48  includes an engagement surface  50  structured to engage the forehead of the user. In prior masks, such an engagement surface  50  would have two top straps extending therefrom in order to help to hold the mask in place. In the embodiment of the mask  46  shown in  FIG. 9 , no such straps are provided. Instead, an adhesive layer  40  is provided on the engagement surface  50  in order to provide a bonding seal between the forehead support  48  and the user&#39;s skin.  FIGS. 10 and 11  are top plan views of forehead supports  48 A and  48 B according to alternative embodiments. The forehead support  48 A includes a hollow silicone rubber structure  52  having an engagement surface  50  on which an adhesive layer  40  is provided. The forehead support  48 B includes a pair of hollow silicone rubber structures  52 A and  52 B each having an engagement surface  50  on which an adhesive layer  40  is provided. Although forehead supports  48 ,  48 A and  48 B are shown for illustrative purposes as one particular type of facial support, it should be understood that other types of facial supports, such as, without limitation, cheek pads, are also possible. 
       FIG. 12  is an isometric view of a patient interface device in the form of a nasal cannula  54  according to further embodiment of the invention. The nasal cannula  54  includes fluid delivery tubes  56 A and  56 B connected to opposite ends of a fluid delivery barrel  58 . The fluid delivery tubes  56 A and  56 B are in fluid communication with a source of fluid (not shown), such as an oxygen source, and deliver the fluid, e.g., oxygen, from the source to the fluid delivery barrel  58 . First and second nasal inserts  60 A and  60 B are in fluid communication with the fluid delivery barrel  58 . The first and second nasal inserts  60 A and  60 B are structured to be received in the nares of a user so that the fluid, e.g., oxygen, can be delivered from the fluid delivery barrel  58  to the nasal passageway of the user. The nasal cannula  54  further includes an attachment mechanism  62  for removeably attaching the nasal cannula  54  to the user&#39;s face to assist in holding the nasal cannula  54  in place while in use. In particular, the attachment mechanism  62  includes a first attachment panel  64 A and a second attachment panel  64 B connected to one another by a connecting strip  66 . As seen in  FIG. 12 , each attachment panel  64 A,  64 B includes an aperture  68 A,  68 B which receives therethrough a respective one of the fluid delivery tubes  56 A and  56 B in order to moveably couple the attachment mechanism  62  to the remainder of the nasal cannula  54 . Each attachment panel  64 A,  64 B includes an inner surface  70  which has provided thereon an adhesive layer  40  in any of the forms described elsewhere herein. 
     Referring to  FIG. 13 , when in use, the first and second nasal inserts  60 A and  60 B are inserted within the nares  72 A and  72 B of the user. In that position, the attachment panels  64 A and  64 B are able to be removeably adhered to the alar sidewalls  74 A and  74 B of the nose  75  of the user. Specifically, the adhesive layers  40  provided on the inner surfaces  70  of the attachment panels  64 A and  64 B are able to be removeably adhered to the alar sidewalls  74 A and  74 B. As a result, the nasal cannula  54  is securely held in place while in use. As will be appreciated, each of the components of the nasal cannula  54  may be molded out of a polymeric material such as, without limitation, silicone rubber or urethane. 
       FIG. 14A  is an isometric view of a patient interface device in the form of a nasal cannula  76  according to an alternate further embodiment of the invention. The nasal cannula  76  is similar to the nasal cannula  54  and, as seen in  FIG. 14A , therefore includes a number of the same components. In nasal cannula  76 , however, the attachment panels  64 A and  64 B are directly affixed on opposite sides of the fluid delivery barrel  58  to respective fluid delivery tubes  56 A and  56 B.  FIG. 14B  is an isometric view of a nasal cannula  76 ′ according to an alternative embodiment which is a variation of the nasal cannula  76  shown in  FIG. 14A  wherein only a single fluid delivery tube  56  is employed.  FIG. 15  is a schematic diagram showing the nasal cannula  76 ′ in use wherein the adhesive layers  40  provided on the inner surfaces  70  of the attachment panels  64 A and  64 B are removeably adhered to the alar sidewalls  74 A and  74 B of the nose  75  of the user. 
     The nasal cannulas  54 ,  76  and  76 ′ shown in  FIG. 12-15  are considered double cannulas because each of them includes two nasals inserts  60 A and  60 B. FIGS.  16 A and  16 B are isometric views of a nasal cannula  78  according to a further alternate embodiment of the present invention. The nasal cannula  78  is a single cannula and as such is structured to be received within a single nare of the user.  FIGS. 16A and 16B  show a nasal cannula  78  adapted for insertion into the user&#39;s left nare as the shape of the attachment panel  64  generally matches contour of the left alar sidewall  74 B of the nose  75  of the user as seen in  FIG. 17 . As will be appreciated, a nasal cannula  78  adapted for insertion into the user&#39;s right nare is also possible. The nasal cannula  78  includes a single fluid delivery tube  56  in fluid communication with a nasal insert  60 . The nasal cannula  78  further includes an attachment mechanism  80  having an attachment panel  64  which includes an aperture  68  which receives therethrough the fluid delivery tube  56 . As seen in  FIGS. 16A and 16B , the end of the attachment mechanism  80  that is opposite the attachment panel  64  is affixed to the bottom of the nasal insert  60 . The attachment panel  64  includes an inner surface  70  which has provided thereon an adhesive layer  40  in any of the forms described elsewhere herein.  FIG. 17  is a schematic diagram showing the nasal cannula  78  in use wherein the adhesive layer  40  provided on the inner surface  70  of the attachment panel  64  is removeably adhered to the left alar sidewall  74 B of the nose  75  of the user. 
       FIG. 18  is an isometric view of a patient interface device in the form of a nasal cannula  82  according to still a further embodiment of the invention. The nasal cannula  82  includes fluid delivery tubes  56 A and  56 B connected to opposite ends of a fluid delivery barrel  84 . The fluid delivery tubes  56 A and  56 B are in fluid communication with a source of fluid (not shown), such as an oxygen source, and deliver the fluid, e.g., oxygen, from the source to the fluid delivery barrel  84 . First and second nasal inserts  60 A and  60 B are in fluid communication with the fluid delivery barrel  84  and are structured to be received in the nares of a user. The fluid delivery barrel  84  includes a first outer top surface  86 A adjacent to the outside of the nasal insert  60 A, a second outer top surface  86 B adjacent to the outside of the nasal insert  60 B, and an inner top surface  88  between the nasal inserts  60 A and  60 B. The first outer top surface  86 A, the second outer top surface  86 B, and the inner top surface  88  each have provided thereon an adhesive layer  40  in any of the forms described elsewhere herein. When in use, the first and second nasal inserts  60 A and  60 B are inserted within the nares  72 A and  72 B of the user. In that position, the first outer top surface  86 A, the second outer top surface  86 B, and the inner top surface  88  are each able to be removeably adhered to the underside of the nose  75  of the user. Specifically, the adhesive layers  40  provided on the first outer top surface  86 A and the second outer top surface  86 B are able to be removeably adhered to the exterior of the user&#39;s nares, and the adhesive layer  40  provided on the inner top surface  88  is able to be removeably adhered to the user&#39;s septum. As a result, the nasal cannula  82  is securely held in place while in use. 
       FIG. 19  is an isometric view of a patient interface device in the form of a nasal cannula  90  according to yet a further embodiment of the invention. The nasal cannula  90  includes fluid delivery tubes  56 A and  56 B connected to opposite ends of a fluid delivery barrel  58 . The fluid delivery tubes  56 A and  56 B are in fluid communication with a source of fluid (not shown), such as an oxygen source, and deliver the fluid, e.g., oxygen, from the source to the fluid delivery barrel  58 . First and second nasal inserts  60 A and  60 B are in fluid communication with the fluid delivery barrel  58 . The first and second nasal inserts  60 A and  60 B are structured to be received in the nares of a user so that the fluid, e.g., oxygen, can be delivered from the fluid delivery barrel  58  to the nasal passageway of the user. The nasal cannula  90  further includes a first attachment panel  92 A and a second attachment panel  92 B that are each connected to the fluid delivery barrel  58 . Each attachment panel  92 A,  92 B includes an inner surface  94  which has provided thereon an adhesive layer  40  in any of the forms described elsewhere herein. When in use, the first and second nasal inserts  60 A and  60 B are inserted within the nares  72 A and  72 B of the user. In that position, the attachment panels  92 A and  92 B are able to be removeably adhered to the exterior of the user&#39;s nares by the adhesive layers  40  provided thereon. As a result, the nasal cannula  90  is securely held in place while in use. 
       FIG. 20  is a schematic diagram showing of a patient interface device in the form of a nasal cannula  96  according to yet a further embodiment of the invention. The nasal cannula  96  includes fluid delivery tubes  56 A and  56 B connected to opposite ends of a fluid delivery barrel  58 . The fluid delivery tubes  56 A and  56 B are in fluid communication with a source of fluid (not shown), such as an oxygen source, and deliver the fluid, e.g., oxygen, from the source to the fluid delivery barrel  58 . First and second nasal inserts  60 A and  60 B are in fluid communication with the fluid delivery barrel  58 . The first and second nasal inserts  60 A and  60 B are structured to be received in the nares  72 A and  72 B of a user so that the fluid, e.g., oxygen, can be delivered from the fluid delivery barrel  58  to the nasal passageway of the user. The nasal cannula  96  further includes a first attachment panel  98 A moveably threaded onto the fluid delivery tube  56 A and a second attachment panel  98 B moveably threaded onto the fluid delivery tube  56 . In particular, the fluid delivery tube  56 A,  56 B is passed through apertures  100  provided in the respective attachment panel  98 A,  98 B so that the attachment panel  98 A,  98 B is able to slide along the fluid delivery tube  56 A,  56 B. As will become apparent below, this allows each attachment panel  98 A,  98 B to be selectively (and independently) positioned by the user. Each attachment pad  98 A,  98 B includes an inner surface which has provided thereon an adhesive layer  40  in any of the forms described elsewhere herein. When in use, the first and second nasal inserts  60 A and  60 B are inserted within the nares  72 A and  72 B of the user. In that position, the attachment panels  98 A and  98 B are able to be removeably adhered to the exterior of the user&#39;s face (e.g., between the nose and mouth) at positions selected by the user by the adhesive layers  40  provided thereon. As a result, the nasal cannula  96  is securely held in place while in use. 
     As will be appreciated, each of the components of the nasal cannulas  76 ,  76 ′,  78 ,  82 ,  90  and  96  may be molded out of a suitable polymeric material such as, without limitation, silicone rubber or urethane. 
     While preferred embodiments of the invention have been described and illustrated above, it should be understood that these are exemplary of the invention and are not to be considered as limiting. Additions, deletions, substitutions, and other modifications can be made without departing from the spirit or scope of the present invention. Accordingly, the invention is not to be considered as limited by the foregoing description but is only limited by the scope of the appended claims.