Patent Publication Number: US-2019184126-A1

Title: Face mask

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application is a Continuation under 35 U.S.C. § 120/121 of U.S. patent application Ser. No. 15/169,024, filed May 31, 2016, which is a Continuation under 35 U.S.C. § 120/121 of U.S. patent application Ser. No. 14/048,120, filed Oct. 8, 2013, now U.S. Pat. No. 9,375,544, granted Jun. 28, 2016, which is a Continuation under 35 U.S.C. § 120/121 of U.S. patent application Ser. No. 12/742,950, filed May 14, 2010, now U.S. Pat. No. 8,573,217, granted Nov. 5, 2013, which claims the priority benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application No. 60/987,843 filed on Nov. 14, 2007, the contents of which are herein incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to therapeutic gas delivery systems and, more particularly, to a mask that forms a seal with a patient&#39;s face during gas delivery. 
     2. Description of the Related Art 
     One class of respiratory face mask assemblies can be of two different types: a single limb circuit type and a dual limb circuit type. For a single limb circuit, the face mask assembly typically includes a valve and an exhaust port, and, for a dual limb circuit, the face mask assembly typically does not include a valve but provides a valveless conduit instead. Other types of masks may also be useful for different applications. Thus, hospitals and other health care facilities typically stock several different types of face mask assemblies that are used for different applications. Cost and storage space considerations associated with stocking several different face mask assemblies can be significant. 
     SUMMARY OF THE INVENTION 
     One aspect of the present invention provides a mask assembly for providing gas to a patient. The mask assembly includes a mask body having an opening for reception of the gas and a breathing circuit interface. The mask body includes a seal structure for sealingly engaging with the face of the patient and surrounding at least the nose and mouth of the patient. The breathing circuit interface includes a first portion rotatably connected with the mask body and a second portion that is constructed and arranged to releasably connect with a conduit for delivering the gas to the patient through the opening. 
     Another aspect of the present invention provides a mask assembly for providing gas to a patient. The mask assembly includes a mask body having an opening for reception of the gas and a conduit. The mask body includes a seal structure for sealingly engaging with the face of the patient and surrounding at least the nose and the mouth of the patient, and a connecting portion. The conduit is releasably connected with the connecting portion of the mask body. The conduit includes a first connector portion which connects with the connecting portion, and a second connector portion that is constructed and arranged to connect with tubing, wherein the first connector portion includes a plurality of recesses at an interface with the connecting portion to allow exhaled gas to escape therethrough. 
     In yet another embodiment, the present invention provides a mask assembly kit for providing gas to a patient. The mask assembly kit includes a mask body having an opening for reception of the gas, a first, valveless conduit, and a second conduit containing a valve. The mask body includes a seal structure for sealingly engaging with the face of the patient and surrounding at least the nose and the mouth of the patient. Each of the conduits includes a first connector portion which connects with a connecting portion associated with the mask body, and a second connector portion constructed and arranged to connect with tubing. The connecting portion of the mask body is constructed and arranged to be selectively attached to the first connector portion of either the first conduit or the second conduit. 
     These and other aspects 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. As used in the specification and in the claims, the singular form of “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a perspective view of the mask assembly and patient&#39;s face in accordance with an embodiment of the present invention; 
         FIG. 1B  is a left side perspective view of the mask assembly and patient&#39;s face in accordance with an embodiment of the present invention; 
         FIG. 2  is a perspective view of the mask assembly with an entrainment valve assembly in accordance with an embodiment of the present invention; 
         FIG. 3  is a perspective exploded view of a mask assembly in accordance with an embodiment of the present invention; 
         FIG. 4  is an upper right perspective view of an air entrainment valve with exhaust ports assembly in accordance with an embodiment of the present invention; 
         FIG. 5  is a left side perspective view of the air entrainment valve with exhaust ports assembly in accordance with an embodiment of the present invention; 
         FIG. 6  is a cross-sectional view of the mask assembly in accordance with an embodiment of the present invention; 
         FIG. 7  is a cross-sectional view of the entrainment valve assembly in accordance with an embodiment of the present invention; 
         FIG. 8  is a perspective view of a valve element in accordance with an embodiment of the present invention; 
         FIG. 9  is a top perspective view of a valve element in accordance with an embodiment of the present invention; 
         FIG. 10  is a perspective view of the mask body and the entrainment valve assembly in accordance with an embodiment of the present invention; 
         FIG. 11  is a perspective view of the mask body and a standard elbow before the assembly in accordance with an embodiment of the present invention; 
         FIG. 12  is a perspective view of the mask body and the standard elbow after the assembly in accordance with an embodiment of the present invention; 
         FIG. 13  is a rear perspective view of the mask assembly in accordance with an embodiment of the present invention; 
         FIG. 14  is a front perspective view of a mask headgear attachment post in accordance with an embodiment of the present invention; 
         FIG. 15  is a rear perspective view of the mask headgear attachment post in accordance with an embodiment of the present invention; 
         FIG. 16  is a side perspective view of the mask headgear attachment post in accordance with an embodiment of the present invention; 
         FIG. 17  is a rear perspective view of a mask headgear attachment clip in accordance with an embodiment of the present invention; 
         FIG. 18  is a front perspective view of the mask headgear attachment clip in accordance with an embodiment of the present invention; 
         FIG. 19  is a cross-sectional view taken through the line A-A in  FIG. 6  and showing the passage of the exhalation grooves through the breathing circuit interface in accordance with an embodiment of the present invention; 
         FIG. 20  is a front perspective view of an alternative embodiment of the mask assembly; 
         FIG. 21  is an exploded front perspective of the mask assembly in accordance with an embodiment of the present invention; 
         FIG. 22  is a front perspective of an alternative mask headgear attachment clip in accordance with an embodiment of the present invention; and 
         FIG. 23  is a rear perspective of an alternative mask headgear attachment clip in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       FIGS. 1A, 1B, 2 and 3  show a mask assembly  10  for use in a therapeutic gas delivery in accordance with an embodiment of the present invention. The mask assembly  10  may generally include a mask body  12  having an opening  13  for reception of gas. The mask body  12  includes a seal structure  20  for sealingly engaging with the face of the patient  27  in surrounding relation to at least the nose and mouth (and optionally the eyes) of the patient  27 . The mask assembly  10 , in one embodiment, also includes a breathing circuit interface  16  for connecting the mask body  12  with a pressurized breathing gas supply. As disclosed in more detail later, the breathing circuit interface  16  has a first portion  17  rotatably connected with the mask body  12  and a second portion  19  constructed and arranged to connect with a conduit  18  for delivering the gas to the patient  27  through the opening  13 . 
     In an embodiment, the breathing circuit interface  16  and the conduit  18  connects the mask body  12 , via a circuit tubing (not shown), to a source of gas (not shown), e.g., a blower, a CPAP machine, a ventilator or other suitable device, for providing breathing gas to the patient  27 . As will be appreciated from further discussions herein, the second portion  19  of the breathing circuit interface  16  is releasably connected with the conduit  18  to enable different types of conduits  18  to be connected to the mask body  12 . In addition, a rotatable or swivel connection between the breathing circuit interface  16  at the first portion  17  thereof with the mask body  12  allows the elbow shaped conduit  18  to rotate after connection to enable the conduit  18  to extend in any direction within a 360° of rotation for connecting with the tubing. It should be appreciated that for some purposes the breathing circuit interface  16  may also be considered to be part of the mask body  12 . 
     As shown in  FIG. 3 , the breathing circuit interface  16  has an annular configuration with a generally cylindrical inner surface  23  disposed about a central opening  29  therethrough. As will be appreciated from more detailed discussions later, the cylindrical inner surface  23  of the breathing circuit interface  16  is shaped and configured to provide a releasable friction fit with a generally cylindrical mating surface  25  of an appropriate conduit  18  that connects with tubing for receiving a breathable gas. 
     A plurality of radially outwardly extending ribs  31 , which have an increasing thickness or radial dimension as they extend from the second portion  19  to the first portion  17  of the breathing circuit interface  16 , are spaced at regular circumferential intervals. The ribs  31  are integrally formed as part of the outer surface of the breathing circuit interface  16 . The plurality of ribs  31  located on the outer surface of the second portion  19  of the breathing circuit interface  16  provides the user  27  (or healthcare personnel) a grip to hold the breathing circuit interface  16  when connecting and disconnecting the conduit  18  to the breathing circuit interface  16 . The ribs  31  also facilitate manual rotation of the breathing circuit interface  16 . 
     In one embodiment, the mask body  12  includes a rigid portion  21 , formed from a clear plastic material, and the aforementioned flexible peripheral seal structure  20 . The flexible peripheral seal structure  20  is attached around the rigid portion  21  of the mask body  12 . A protrusion  60  extends forwardly from a forward central portion of the rigid portion  21  of the mask body  12  and is shaped to accommodate the nose and the mouth of the patient  27 . The protrusion  60  is generally pear shape about its periphery  62 , where it meets the flatter parts  64  of the rigid portion  21  and includes the opening  13  located in the forwardmost portion thereof. The protrusion  60  includes a pair of indentations  68  located horizontally on either side of the opening  13 . The pair of indentations  68  serves as finger receiving indentations and provides a region for an individual to grip the mask body  12  when placing and removing the mask body  12  on the patient&#39;s face. 
     In one embodiment, the mask body  12  is adapted to be connected with headgear assembly  11  that can be used to mount the mask body  12  on the head of the patient  27 . In an embodiment, a pair of headgear attachment clips  14  provided for interface and connection with lower headgear mounting strap portions  40  of the headgear assembly  11 . A pair of headgear attachment members  22  is provided for connectably receiving the headgear attachment clips  14 , and a pair of spaced upper headgear strap retaining tabs  24 , each having an elongated opening  50  therethrough, is provided for receiving upper headgear mounting strap portions  40  of the headgear assembly  11 . The pair of headgear retaining tabs  24  is disposed on the opposite upper sides of the rigid portion  21  of the mask body  12 . The pair of headgear attachment members  22  is disposed on opposite, lower sides of the rigid portion  21  of the mask body  12 . Each headgear retaining tab  24  is integrally formed with rigid portion  21  and extends outwardly from the flexible peripheral seal structure  20 , as best seen in  FIGS. 2 and 3 . 
       FIG. 4  shows a conduit  18  in accordance with one embodiment. In this embodiment, the conduit  18  is an entrainment valve assembly  200 . The entrainment valve assembly  200  comprises a generally an elbow shaped tubular member  201  formed from a rigid plastic material, such as polycarbonate or other plastic material as would be appreciated by one skilled in the art. In one embodiment, the tubular member  201  is formed from a clear, colorless, plastic material. Tubular member  201  includes a primary inlet  202 , a secondary inlet  204  and an outlet  206 . 
     Tubular member  201  includes a first connector portion  230  and a second connector portion  232 . The first connector portion  230  and the second connector portion  232  are generally cylindrical in shape and are generally disposed perpendicular to each other. The first connector portion  230  and second connector portion  232  is joined by a bent tubular region  233 . The first connector portion  230  has aforementioned generally cylindrical outer surface  25  for connection with the breathing circuit interface  16 , while the second connector portion  232  also has a cylindrical outer surface  205  for frictionally mating with the inner surfaces of tubing. 
     The second connector portion  232  is connected to the breathing circuit tubing (not shown) and receives pressurized gas from a source of pressurized gas (e.g., air from a CPAP machine, a blower, a ventilator or other ventilation device). 
     The secondary inlet  204  of the entrainment valve assembly  200  comprises an opening  254  located towards the bent tubular region  233 . The opening  254  is divided into two equal, generally semi-cylindrical segments by a planar wall  256 . The planar wall  256  of the entrainment valve assembly  200  extends through the cylindrical opening  254 . The opening  254  allows the user  27  to breath in from and out to atmosphere in the absence of pressurized gas flow being provided into inlet  202 . The entrainment valve assembly  200 , at cylindrical surface  25 , further includes a plurality of exhalation grooves  258 . The grooves  258  are located at an interface where the entrainment valve assembly  200  connects with the breathing circuit interface  16  as will be more fully appreciated from  FIG. 19 . The plurality of the exhalation grooves  258  are circumferentially spaced on surface  25  and placed symmetrically on either side of the first connector portion  230 . Other embodiments are contemplated in which the exhalation grooves  258  are located anywhere on the outer surface of the first connector portion  230 , where it interfaces with breathing circuit interface  16 . 
     As clearly shown in  FIG. 3 , the four exhalation grooves  258  on each side of the entrainment valve tubular member  201  are placed at an angle with respect to the horizontal axis on the surface  25  of the entrainment valve  200 . Specifically, when the tubular member  201  is connected to the rigid portion  21  such that the second connector portion  232  of the tubular member  201  points downwards, the four exhalation grooves  258  on one side of the tubular member  201  point upwards at an angle whereas the four exhalation grooves  258  on the other side of the tubular member  201  point downwards at an angle. The angular positioning of the grooves  258  allows the exhaled gas to exit the mask in a swirling motion. In addition, the angled groove  258  aid in providing a releasable friction fit between the cylindrical mating surface  25  of the entrainment valve assembly  200  and the cylindrical inner surface  23  of the breathing circuit interface  16 . 
     The exhalation grooves  258  are sufficiently long so that, when the entrainment valve assembly  200  is pushed as far as it can go into the breathing circuit interface  16 , the grooves  258  still extend outwardly from the breathing circuit interface  16  and provide a path for allowing the exhaled gas to exit through the grooves  258 . In addition, for any extent of friction fitting engagement between the surfaces  23 ,  25 , the cross-sectional area of the gap or space provided by the grooves  258  will be constant, so that the expired gas flow path to the exterior of the mask  258  provides constant resistance, irrespective of whether the entrainment valve assembly  200  is fully inserted or somewhat less than fully inserted into the breathing circuit interface  16 . 
     Referring to  FIG. 5 , the entrainment valve assembly  200  includes a pressure port  260 . The pressure port  260  extends from the bent tubular region  233  of the entrainment valve assembly  200  and is generally parallel to the second connector portion  232  of the entrainment valve assembly  200 . A removable cap  262  is used to close the pressure port  260 . The cap  262  includes gripping tab  264  to aid in removal of the cap  262  from the pressure port  260 . A sampling tube (not shown) may be disposed in fluid communication with the gas within tubular body  201  through the pressure port  260 . A transducer (not shown) can be secured to the sampling tube, and a processor communicates with the transducer. The processor calculates at least one respiratory parameter using the signal from the transducer. This is generally used to measure pressure by the ventilator as control feedback to the ventilator. 
     As shown in  FIGS. 6 and 7 , the breathing circuit interface  16  includes the aforementioned first portion  17  and second portion  19 . The first portion  17  is generally circular in shape and includes an annular flat wall  408  that engages a radially inwardly extending flange portion  70  in slidable surface relationship. The flange portion  70  surrounds opening  13  in the rigid portion  21  of the mask body  12  (see  FIG. 3 ). The first portion  17  of the breathing circuit interface  16  further includes generally cylindrical protruding portion  409  that extends outwardly from a radially innermost portion of annular surface  408 . The cylindrical protruding portion  409  extends into the opening  13  in the rigid portion  21  of the mask body  12 . The cylindrical protruding portion  409  has a groove  410  located in the outer cylindrical surface thereof (see  FIG. 7 ). The groove  410  accommodates a connecting washer or a bearing  412 . The washer  412  in one embodiment is a split ring washer structure that has an outer periphery thereof that bears against the inner surface of the flange  70 , and its inner periphery received groove  410  so as to rotatably connect the breathing circuit interface  16  with the mask body  12 . Thus, the breathing circuit interface  16  is rotatably connected with the rigid portion  21  of the mask body  12 . Slight friction at the rotatable interface may, in one embodiment, provide at least resistance to rotation, so that the rotational position of the breathing circuit interface  16  can be manually set as desired, and it will retain that position so that the leg or the second connector portion  232  of the conduit  18  that connects with tubing can be positioned in a desired direction that is generally retained unless intentionally altered. In another embodiment, the friction at the point of rotation can be minimal, to allow free rotation of the breathing circuit interface  16 . 
     In another embodiment, the connection between the breathing circuit interface  16  and the rigid portion  21  of the mask body  12  may be achieved by using a ball bearing arrangement or any other type bearing arrangement that allows a rotating motion of the breathing circuit interface  16  with respect to the mask body  12 . 
     As discussed above, the inner surface  23  of the breathing circuit interface  16  is shaped and configured to engage detachably with an outer surface  25  of the entrainment valve assembly  200  by a friction-fit. In addition to allowing friction fit with the entrainment valve assembly  200 , the inner surface  23  of the breathing circuit interface  16  allows the entrainment valve assembly  200  to be removed and interchangeably friction fitted with different, other types of the conduits  18  through a similar friction fit, as will be described in more detail later. The diameter of the first connector portion  230  is larger than the diameter of the second connector portion  232  of the entrainment valve assembly  200  to prevent the wrong end of the valve assembly  200  from being connected with interface  16 . 
     The entrainment valve assembly  200  includes a valve member  208 . The valve member  208  is connected to the tubular member  201  at connection region  248  thereof by means of a recess  250  and a barb  526  and a stop member  528  provided in the valve member  208  (see  FIGS. 8 and 9 ). A rib  252  (see  FIG. 7 ), located on the lower portion of the bent tubular region  233  of the entrainment valve assembly  200 , has an outer surface thereof that is received in recess  250  so as to clamp the connecting region  248  against a portion  234  of an annular flange  253 . 
     The valve member  208  has a sealing portion  520 , having a relatively thin, flat, oval configuration. The sealing portion  520  is made of a flexible material and thus capable of bending upwardly (as shown in the dashed lines in  FIG. 7 ) in response to pressurized gas being forced into the primary inlet  202 . The upward bending continues until an upper surface  522  of the sealing portion  520  engages an annular lip  235  at the end of a cylindrical wall  254  protruding into the tubular body  201  and defining the secondary inlet  204 . The direction of travel of the sealing portion  520  from its rest position to the upper bent portion is shown by arrow A in  FIG. 7 . In this upper bent portion, the sealing engagement of the upper surface  522  of the valve member  208  with annular lip  235  causes the secondary inlet  204  to be sealed so that pressurized gas provided into the primary inlet  202  does not escape through the secondary inlet  204 . 
     It should be noted that where gas is not being provided to the patient through the primary inlet  202  (e.g., the blower connected with the primary inlet  202  is not operating), the secondary inlet  204  may serve as both an inlet passage of atmospheric air provided to the patient during inhalation and an outlet passage for exhalation. In this instance, the sealing portion  520  may remain at its at rest position, wherein it forms a seal with an upper surface  259  of the annular flange  253 , as shown in  FIG. 7 . 
     The valve member  208  can be made from rubber, latex, silicone, or any other elastomeric material as would be appreciated by one skilled in the art. 
     As can be appreciated most readily from  FIG. 4  and  FIG. 19  (which is a cross-sectional view taken through A-A in  FIG. 6 ), the exhalation grooves  258  form a passage between the exterior surface  25  of the tubular portion  201  and the interior cylindrical surface  23  of the breathing circuit interface  16 . In one embodiment, the exhalation grooves  258  are provided on opposite lateral sides of the exterior surface  25  of the tubular portion  201 . In another embodiment, the exhalation grooves may be provided on the inner surface  23  of the breathing circuit interface  16  rather than on body  201 . In addition, as shown as dashed lines in  FIG. 7 , in another embodiment they may alternatively, or also, be located at the top portion of the exterior surface  25  of the body  201 . When the user inhales, a very small fraction of gas may be drawn from atmosphere through the exhalation grooves  258 . However, by and large, the pressurized gas forced into the primary inlet  202  will create higher pressure within the body  201  than the atmospheric pressure, so that air is mostly forced outwardly through the exhalation passages  258  (rather than inwardly), even during inhalation. Moreover, as the user exhales, the exhaled gas impacts the centrally incoming airflow through the body  201  and is thus forced to mushroom radially outwardly resulting in a circular flow pattern that effectively flushes the exhaled gas, and is thus generally directed toward and through the peripheral exhalation grooves  258  to atmosphere. 
     As best seen in  FIG. 6 , the flexible peripheral seal portion  20  may have a generally rectangular channel shaped cross-sectional configuration with three sides  504 ,  506  and  508 . The flexible peripheral seal structure  20  may be attached to the mask body  12  at side  504 . An edge  500  of the rigid portion  21  of the mask body  12  engages with an opening  502  located in the side  504  of the flexible peripheral seal structure  20 , such that a layered connection is formed. The parts are then adhered in place, through an adhesive connection, an ultrasonic weld connection, a riveted or a pinned connection or any other type of connection as would be appreciated by one skilled in the art. Other embodiments are contemplated in which there is no overlap, such as by attaching the rigid portion  21  and flexible peripheral seal structure  20  with their edges end to end (e.g., by an adhesive connection). The side  506  is located between side  504  and side  508 , providing a gap between sides  504  and  508 . This gap may provide flexibility to the flexible peripheral seal portion  20 , as it conforms to the face of the user  27 . The corners of the flexible peripheral seal portion  20  may be generally rounded. The length of the sides  508  and  506  may vary along the periphery of the seal structure  20  so as to provide a conforming sealing engagement of the mask body  12  with the face of the patient  27 . 
       FIGS. 10-12  show the replaceable and interchangeable concept of the conduit  18  with respect to the breathing circuit interface  16 . Specifically, in  FIGS. 10-12 , the entrainment valve assembly  200  is shown being replaced by a standard elbow  300 , both of which can be used as examples for the conduit  18 . However, as discussed later, other elbow configurations may also be friction fitted with the breathing circuit interface  16 . 
       FIG. 10  shows the entrainment valve assembly  200  having been removed from the mask assembly  10 . This can be done by simply pulling the entrainment valve assembly  200  away from the mask assembly  10  to release friction fit as discussed earlier.  FIGS. 11 and 12  show the mask assembly  10  being connected with the standard elbow  300  by a similar friction fit. The standard elbow  300  has no internal valve and no exterior exhalation grooves. The standard elbow  300  provides a tubular, elbow shaped body  301  that is otherwise similar to tubular body  201  for providing a connection between the breathing circuit interface  16  and the tubing that will provide breathing gas to the mask assembly  10 . The standard elbow  300  may optionally be provided with the pressure port  260  and pressure cap  262  as discussed with respect to the entrainment valve assembly  200 . In one embodiment, body  301  is formed from a clear (transparent), but colored (e.g., blue) plastic material. 
     The removable and replaceable conduits  18  enable the mask assembly  10  to be functional for different uses, simply by employing the conduit  18  of choice. 
     Though  FIGS. 10-12  show the mask assembly  10  that is adapted to accommodate the entrainment valve assembly  200  and standard elbow  300  interchangeably, listed below are some non-limiting examples of other types of conduits  18  that can be used interchangeably with the mask assembly  10  described above:
         Conduit with a bronchoscope port to permit the care giver to perform a bronchoscopy procedure with mask on   Conduit with aerosol generator adapter to deliver medication during NIV   Conduit with MDI port to deliver medication using a “Metered Dose Inhaler”   Conduit with port to accommodate a CPAP relief valve   Conduit with C02 sensor capabilities to monitor patient   Conduit with Volumetric C02 sensor capabilities to monitor patient VC02   Conduit that entrains Heliox or other specialty gases   Conduit that adds moisture to inhaled gas   Conduit that includes an HME [Heat moisture exchanger]   Conduit that incorporates “nano” sensors for a variety of clinical monitoring capabilities   Conduit with Filtered Exhalation [useful in pandemic situations like SARS]   Conduit that enhances the patients ability to “Speak with Mask On”   Conduit that accommodates a NG feeding tube   Conduit that reduces/control C02 re-breathing   Conduit that aids in secretion clearance   Conduit with Standard Elbow   Conduit that can be used on a wide range of mask types [Such as Full, Nasal or Total or Helmet]       

     It should be appreciated, that the above listed conduit configurations provide non-limiting examples of different types, configurations and/or constructions of conduits that can be provided. It should be appreciated that, while these conduits may all be provided with an elbow shaped tubular body; other tubular shapes (such as a straight tubular configuration) may alternatively be provided. 
     Other embodiments are contemplated in which the connection between the conduit  18  and the breathing circuit interface  16  is not a friction fit, but may be achieved by virtue of other types of connections such as a quarter-turn type connection, a snap fit, or any other locking mechanism that provides a detachable connection between the conduit  18  and the breathing circuit interface  16 . 
     In yet another embodiment, the first connector portion  230  of the conduit  18  may itself be provided with a swivel coupling, similar to the breathing circuit interface  16 , rather than such structure being provided as part of the mask. In that case, the swivel coupling of the elbow can be connected directly to a non-swiveled portion (e.g., an outwardly projecting cylindrical configuration) surrounding the opening  13  in the rigid portion  21  of the mask body  12 . 
     In yet another embodiment, no swivel coupling is provided. Rather, a direct connection between the tubular body (e.g.,  201  or  301 ) is provided with a correspondingly shaped portion of the rigid portion  21  of the mask. In this embodiment, some rotation of the conduits  18  may nevertheless be accommodated via direct sliding friction at the friction fit connection between rigid portion  21  and the tubular body. However, it is further contemplated that other, non-rotational connections may also be provided and will still enable the modularity of design contemplated herein. 
     In one aspect of the invention, a mask assembly kit is provided. The kit assembly includes the mask body  12 , with or without the rotatable interface  16 , and at least two conduits  18  of different types to enable the mask body  12  to provide different functionality simply by changing conduit types. For example, the standard elbow  300  (valveless) can be provided as one conduit, and the entrainment valve assembly  200  can be provided as another conduit. More than two conduits may be provided, and more than one mask may be provided, although each of the masks will have a common configuration, while the conduits will have at least two different configurations that fit the mask body. 
       FIG. 13  shows a rear perspective view of the mask assembly  10 . The flexible seal structure  20  can be clearly seen here. Also shown are the headgear strap retaining tabs  24  and portions of headgear attachment members  22 , which are partially obstructed by the headgear attachment clips  14 .  FIGS. 14-16  show the headgear attachment members  22  more clearly. The headgear attachment members  22  are integrally formed with the rigid portion  21  and extend outwardly therefrom, beyond the flexible peripheral seal structure  20 . Specifically, the headgear attachment members  22  each have a generally flat web portion  78  integrally connected with the rigid portion  21  of the mask body  12 , and a connecting post or barrel  82  disposed at the outer end of the web portion  78 . The web portion  78  gradually tapers from the mask body  12  to the barrel  82 . The headgear attachment members  22  each include a front surface  84  and a rear surface  86 . A reinforcement rib  88 , which extends along the web  78  from the mask body  12  to the barrel  82 , is provided on the rear surface  86  on each of the webs  78 . Each barrel or post  82  includes a front face  90  and a rear face  92 . The front face  90  of the barrel  82  is generally semi-cylindrical in shape with a groove  94  located centrally thereof, as best seen in  FIG. 14 . The front face  90  has an upper semi-cylindrical surface portion  91  and a lower semi-cylindrical surface portion  93  on opposite sides of groove  94 . The rear face  92  of the barrel  82  includes a channel  96  located between opposite ends  104  and  106  of the barrel  82 . The channel  96  is divided into four segments by three generally semi-circular projections  108 ,  110  and  112  (top projection  108 , middle projection  110 , and bottom projection  112 ). The thickness of the central circular projection  110  is greater than the thickness of the circular projections  108  and  112 . 
       FIGS. 17 and 18  show one of the headgear attachment clips  14 . The headgear attachment clips  14  each include a front face  116 , a rear face  118 , a top face  120 , a bottom face  122 , a first side face  124  and a second side face  126 . When the headgear attachment clip  14  is assembled with the mask body  12 , the top face  120  faces upwards towards the headgear strap retaining tabs  24  of the mask body  12 , the bottom face  122  faces away from the headgear strap retaining tabs  24  of the mask body  12 , the first side face  124  faces the mask body  12 , and the second side face  126  faces away from the mask body  12 . Finger indentations  128  having gripping ribs  129  are located on the top face  120  and the bottom face  122  of the headgear attachment clips  14 . The gripping ribs  129  provide a region for the patient  27  or care giver to grip the headgear attachment clips  14  while securing or removing the headgear assembly  11  with the mask body  12 . The headgear attachment clips  14  include an elongated opening  130  that receives the straps  40  of the headgear assembly  11 . 
     As shown in  FIG. 17 , the rear face  118  of the headgear attachment clips  14  includes a cavity  134 , which is generally rectangular in shape and includes three cam fingers  136 ,  138  and  140  that extend from a wall  133  defining one side of the elongated opening  130 . The cam fingers  136 ,  138  and  140  extend about half way through the cavity  134 . The thickness of the central cam finger  138  is greater than the thickness of the upper and lower cam fingers  136  and  140  respectively. The cam fingers  136 ,  138  and  140  are generally rectangular in shape and connected along one side to wall  133  and on the bottom to a bottom wall  137  of the cavity  134 . Each of the cam fingers  136 ,  138  and  140  has a chamfered edge located on the top corners  139  that are located away from the side wall  133 . The edges  145  of the cam fingers  136  and  140  that extend downwardly from the corners  139  are sloped at a positive angle so that they extend away from wall  133  as they extend downwardly to join bottom wall  137 . In contrast, the chamfered corner  139  on the central cam finger  138  terminates at a hard corner  141  that protrudes slightly beyond the edges  145  of cam fingers  136  and  140 , and then extends at a negative angle to form an undercut, such that its forward edge  149  extends slightly in a direction towards wall  133  as it extends towards bottom wall  137 . The hard corner  141  provides a primary point of camming contact with the barrel  82  (and in particular, central projection  110  thereof) to lock and unlock (or connect and disconnect) the barrel  82  to the headgear attachment clip  14  as will be described. The cavity  134  includes an elongated channel  135  that does not contain the cam fingers  136 ,  138  and  140 . An outer wall  148  of the headgear attachment clip  14  defines one end of the cavity  134 , opposite the wall  133 . The top portion of wall  148  includes a chamfered top portion  151 , and also includes a pair of overhangs  143 . The overhangs  143  serve a similar function to the hard corner  141 , but engage with semi-cylindrical surfaces  91  and  93  respectively (see  FIG. 14 ), as will be described. 
     As shown in  FIG. 18 , the front face  116  of the headgear attachment clips  14  includes three rectangular openings  142 ,  144  and  146  that are located in the wall  137 . The three rectangular openings  142 ,  144  and  146  extend into the channel  135  of the cavity  134  on the rear face  118  (see  FIG. 17 ). The openings  142  and  146  are disposed closely to outer wall  148 , while the opening  144  is offset and disposed at the bottom of sloping surface  149  of cam finger  138 . 
     The headgear attachment clips  14  along with the headgear straps  40  are connected to their respective headgear attachment members  22  by moving the headgear attachment clips  14  toward the barrels  82  so that the channel  135  of the headgear attachment clips  14  are forced onto the barrels  82  of the headgear attachment members  22 . Specifically, the cam finger  138  (and specifically, the hard corner  141 ) of the headgear attachment clips  14  engages with the corresponding semi-circular projection  110  of the barrel  82 , and the overhangs  143  of the headgear attachment clips  14  engage with the surfaces  91  and  93  on the opposite side of the barrel  82 . A camming motion between the cam finger  138  of the headgear attachment clips  14  and the corresponding circular projection  110  of the barrel  82  of the headgear attachment members  22  causes a bending of the web portions  78 , and a slight flexing of the cam finger  138  and/or circular projection  110  to allow the circular projection  110  to move past the hard corner  141  and into the channel  135 . Similarly, the flexing movement of web  78 , together with slight flexing of the overhangs  143  and/or surfaces  91  and  93  enable the surfaces to be cammed passed the overhangs  143 . When the barrel  82  is disposed within channel  135 , the overhangs  143  and the hard corner  141  prevents the barrel  82  from escaping the channel  135 . The overhangs  143  of the headgear attachment clips  14  engage with the surfaces  91  and  93  on the opposite side of the barrel  82 , thus allowing for rotation of the headgear attachment clip  14  during adjustment or to accommodate different head sizes. 
     In one embodiment, rather than a camming action the headgear attachment clips  14  are pulled off or pushed onto the headgear attachment members  22  by a snapping action over hard corners  141  without camming, and the cam finger  138  of the headgear attachment clips  14  engages with the corresponding semi-circular projection  110  of the barrel  82 . 
     To remove headgear attachment clips  14 , the user  27  or caregiver places his fingers on the finger indentations  128  and pulls the headgear attachment clips  14  in a direction away from the flexible peripheral seal structure  20  towards the protrusion  60 . The headgear attachment clips  14  rotate about an axis defined by the barrel  82  until the chamfered top portions  151  of the wall  148  engages the front surface  84  of the web  78 . Rotational force applied to the headgear attachment clips  14  (e.g., manual force) in a direction forcing surface  151  against surface  84  causes a camming action that creates a flexing of the aforementioned parts and surfaces that lock barrel  82  within channel  135 , so as to cam the barrel  82  out of locking engagement within the channel  135 . In one embodiment, the headgear attachment clips  14  may be molded from a plastic material, but other materials such as rubber, elastomeric material, or metal are also contemplated. 
     In another embodiment of the headgear attachment clips  14  as shown in  FIGS. 20-23 , the headgear attachment clips  14  each include a front face  116 , a rear face  118 , a top face  120 , a bottom face  122 , a first side face  124  and a second side face  126 . When the headgear attachment clip  14  is assembled with the mask body  12 , the top face  120  faces upwards towards the headgear strap retaining tabs  24  of the mask body  12 , the bottom face  122  faces away from the headgear strap retaining tabs  24  of the mask body  12 , the first side face  124  faces the mask body  12 , and the second side face  126  faces away from the mask body  12 . The headgear attachment clips  14  include an elongated opening  130  that receives the straps  40  of the headgear assembly  11 . In addition, this embodiment includes an auxiliary elongated opening  152 . The elongated opening  152  is defined by an inner auxiliary wall  154 , an outer auxiliary wall  156 , and side auxiliary walls  158 . The inner auxiliary wall extends from bottom face  122 . 
     As shown in  FIG. 23 , the rear face  118  of the headgear attachment clips  14  includes a cavity  134 , which is generally rectangular in shape and includes three cam fingers  136 ,  138  and  140  that extend from a wall  133  defining one side of the elongated opening  130 . The cam fingers  136 ,  138  and  140  extend about half way through the cavity  134 . The thickness of the central cam finger  138  is greater than the thickness of the upper and lower cam fingers  136  and  140  respectively. The cam fingers  136 ,  138  and  140  are generally rectangular in shape and connected along one side to wall  133  and on the bottom to a bottom wall  137  of the cavity  134 . Each of the cam fingers  136 ,  138  and  140  has a chamfered edge located on the top corners  139  that are located away from the side wall  133 . The edges  145  of the cam fingers  136  and  140  that extend downwardly from the corners  139  are sloped at a positive angle so that they extend away from wall  133  as they extend downwardly to join bottom wall  137 . In contrast, the chamfered corner  139  on the central cam finger  138  terminates at a hard corner  141  that protrudes slightly beyond the edges  145  of cam fingers  136  and  140  to form an undercut, and then extends at a negative angle, such that its forward edge  149  extends slightly in a direction towards wall  133  as it extends towards bottom wall  137 . The hard corner  141  provides a primary point of camming contact with the barrel  82  (and in particular, central projection  110  thereof) to lock and unlock (or connect and disconnect) the barrel  82  to the headgear attachment clip  14  as will be described. The cavity  134  includes an elongated channel  135  that does not contain the cam fingers  136 ,  138  and  140 . An outer wall  148  of the headgear attachment clip  14  defines one end of the cavity  134 , opposite the wall  133 . The top portion of wall  148  includes a chamfered top portion  151 , and also includes a pair of overhangs  143 . The overhangs  143  serve a similar function to the hard corner  141 , but engage with semi-cylindrical surfaces  91  and  93  respectively (see  FIG. 14 ), as will be described. 
     As shown in  FIG. 22 , the front face  116  of the headgear attachment clips  14  includes three rectangular openings  142 ,  144  and  146  that are located in the wall  137 . The three rectangular openings  142 ,  144  and  146  extend into the channel  135  of the cavity  134  on the rear face  118  (see  FIG. 23 ). The openings  142  and  146  are disposed closely to outer wall  148 , while the opening  144  is offset and disposed at the bottom of sloping surface  149  of cam finger  138 . 
     The headgear attachment clips  14  along with the headgear straps  40  are connected to their respective headgear attachment members  22  by moving the headgear attachment clips  14  toward the barrels  82  so that the channel  135  of the headgear attachment clips  14  are forced onto the barrels  82  of the headgear attachment members  22 . Specifically, the cam finger  138  (and specifically, the hard corner  141 ) of the headgear attachment clips  14  engages with the corresponding semi-circular projection  110  of the barrel  82 , and the overhangs  143  of the headgear attachment clips  14  engage with the surfaces  91  and  93  on the opposite side of the barrel  82 . A camming motion between the cam finger  138  of the headgear attachment clips  14  and the corresponding circular projection  110  of the barrel  82  of the headgear attachment members  22  causes a bending of the web portions  78 , and a slight flexing of the cam finger  138  and/or circular projection  110  to allow the circular projection  110  to move past the hard corner  141  and into the channel  135 . Similarly, the flexing movement of web  78 , together with slight flexing of the overhangs  143  and/or surfaces  91  and  93  enable the surfaces to be cammed passed the overhangs  143 . When the barrel  82  is disposed within channel  135 , the overhangs  143  and the hard corner  141  prevents the barrel  82  from escaping the channel  135 . The overhangs  143  of the headgear attachment clips  14  engage with the surfaces  91  and  93  on the opposite side of the barrel  82 , thus allowing for rotation of the headgear attachment clip  14  during adjustment or to accommodate different head sizes. 
     In this embodiment, the mask assembly may be provided with an additional strap, not shown, connected between the auxiliary openings  152  and below the chin. This construction provides additional under-the-chin support for the mask  12  to hold it in place rather than permitting it to ride up the patient&#39;s face. 
     The flexible peripheral seal structure  20  of the mask body  12  may be made of a relatively soft and/or flexible material so that the flexible peripheral seal structure  20  conforms to the shape of a patient&#39;s face when held against it. The flexible peripheral seal structure  20  may be made of, for example, silicone, an elastomeric material or any other suitable shape conforming material as will be appreciated by one skilled in the art. Different regions of the flexible peripheral seal structure  20  around the perimeter of the mask body  12  may have different cross-sectional configurations. Various other flexible peripheral seal structure  20  configurations will become apparent to those skilled in the art. The flexible peripheral seal structure  20  is generally annular to form a seal around the nose and the mouth and may be generally oblong shaped, pear shaped (as shown in  FIG. 13 ) or any other suitable shape as will be appreciated by one skilled in the art. The rigid portion  21  of the mask body  12 , in one embodiment, is made of a relatively more rigid material than the flexible peripheral seal structure  20 . For example, mask body  12  may be made from polycarbonate, or other suitable material. 
     The mask body  12  may be formed by a two-step insert molding process. For example, the rigid portion  21  may be molded first and then inserted into a second mold for the flexible peripheral flexible peripheral seal structure  20 , which is injection molded to form around and/or into the rigid portion  21 . 
     In one embodiment, the headgear assembly  11  that is used to mount the mask body  12  to the head of a patient  27  takes the form of straps. However, any structure that secures the mask body  12  to the head of a patient can be used. In the illustrated embodiment as shown in  FIGS. 1A and 1B , an end potion  41  of each of the two headgear straps  40  (only one shown in  FIG. 1B ) is threaded through the elongated opening  50  of the headgear retaining tab  24 , and the end portion  41  of the lower headgear straps  40  are threaded through the elongated opening  130  of the headgear attachment clip  14 . In one embodiment, the end portion  41  comprise hook material and is bent back into engagement with the adjoining surface  401 , formed of loop material, on the straps  40  so as to form a hook and loop (or VELCRO) type connection. It is to be appreciated, however, that there are numerous other ways for securing the end portion of the headgear strap to itself or to the headgear attachment clip  14  and/or to the headgear attachment tab  24 , such as a snap connection, buckle, or locking clamp, as non-limiting examples. The headgear  11  is adjustable, as the straps  40  can be pulled further through the opening  50  of the headgear retaining tab  24  or the elongated opening  130  of the headgear attachment clip  14  to accommodate smaller diameter head sizes. 
     In addition, in another embodiment, a more permanent attachment of the end portion of the headgear strap  40  to the headgear strap retaining tabs  24  or the headgear attachment clips  14  may be provided. For example, once the patient/user  27  sets the headgear strap  40  to the desired length and threaded in through the elongated opening  50  of the headgear strap retaining tabs  24  or the elongated opening  130  of the headgear attachment clips  14 , the free end of the strap  40  can be permanently fixed back onto the strap  40 , such as by gluing, sewing, or riveting the overlapping straps together. The straps  40  of the headgear assembly  11  may be elastic or inelastic, and may extend around the back of the head of the patient  27  to secure the mask body  12  on the patient  27 , with the flexible peripheral seal structure  20  in sealing engagement with the patient&#39;s face. 
     The mask, as shown in  FIG. 1 , is a total face mask that accommodates substantially the entire facial area (including the nose, the mouth and the eyes) of the patient. It is to be understood, however, that the present invention also contemplates an oral/nasal mask that accommodates only the mouth and the nose of a user. The configuration of the mask may vary and is not limited to a particular size or configuration, as patients may range in age, size, and/or medical purpose so as to require appropriate selection from among a variety of different mask sizes and configurations as would be appreciated by one skilled in the art. In one embodiment, the size of the face mask is embossed on the lower end portion of the flexible peripheral seal structure  20  as shown by  600  in  FIG. 13 . 
     Although the invention has been described in detail for the purpose of illustration based on what is currently considered to be the most practical and preferred embodiments, it is to be understood that such detail is solely for that purpose and that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover modifications and equivalent arrangements that are within the spirit and scope of the appended claims. For example, it is to be understood that the present invention contemplates that, to the extent possible, one or more features of any embodiment can be combined with one or more features of any other embodiment.