Nasal prong and patient interface device including the same

CROSS-REFERENCE TO RELATED APPLICATIONS

0001This patent application claims the priority benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 61/805,605 filed on Mar. 27, 2013, the contents of which are herein incorporated by reference.

BACKGROUND OF THE INVENTION

00021. Field of the Invention

0003The present invention pertains to patient interface devices for delivering a flow of breathing gas to a patient during, for example, respiratory therapy, and, in particular, to nasal prongs adapted for use with patient interface devices.

00042. Description of the Related Art

0005Obstructive sleep apnea (OSA) is a condition that affects millions of people from around the world. OSA is characterized by disturbances or cessation in breathing during sleep. OSA episodes result from partial or complete blockage of airflow during sleep that lasts at least 10 seconds and often as long as 1 to 2 minutes. In a given night, people with moderate to severe apnea may experience complete or partial breathing disruptions as high as 200-500 per night. Because their sleep is constantly disrupted, they are deprived of the restorative sleep necessary for efficient functioning of body and mind. This sleep disorder has also been linked with hypertension, depression, stroke, cardiac arrhythmias, myocardial infarction and other cardiovascular disorders. OSA also causes excessive tiredness.

0006One method for treating OSA is positive airway pressure (PAP) therapy. Known PAP therapies include continuous positive airway pressure (CPAP), wherein a constant positive airway pressure is provided to the airway of the patient in order to splint the patient's airway open, and variable airway pressure, wherein the pressure provided to the airway of the patient is varied with the patient's respiratory cycle. Such therapies are typically provided to the patient at night while the patient is sleeping.

0007Non-invasive ventilation and pressure support therapies as just described involve the placement of a patient interface device, which is typically a nasal or nasal/oral mask, on the face of a patient to interface the ventilator or pressure support system with the airway of the patient so that a flow of breathing gas can be delivered from the pressure/flow generating device to the airway of the patient.

0008Because patient interface devices are typically worn for an extended period of time, a variety of concerns must be taken into consideration. For example, in providing CPAP to treat OSA, the patient normally wears the patient interface device all night long while he or she sleeps. One concern in such a situation is that the patient interface device is as comfortable as possible, otherwise the patient may avoid wearing the interface device, defeating the purpose of the prescribed pressure support therapy. Another concern is that an improperly fitted patient interface device can include gaps between the patient interface device and the patient that cause unwanted leakage. Thus, it is desirable to select a patient interface device that properly fits a patient.

0009One type of patient interface device is a nasal pillows mask. Typically, nasal pillows masks use a silicone sealing cushion having silicone nasal prongs that are received within the patient's nares to seal in and around the opening of the nares. However, silicone nasal prongs may not provide optimal comfort for the patient.

SUMMARY OF THE INVENTION

0010Accordingly, it is an object of the present invention to provide a patient interface device that overcomes the shortcomings of conventional patient interface devices. This object is achieved according to one embodiment of the present invention by providing a nasal prong for a cushion member adapted for use with a patient interface device, wherein the nasal prong advantageously deforms to form a seal with a nostril of the patient.

0011In one embodiment, a nasal prong for a cushion member adapted for use with a patient interface device is provided. The nasal prong includes a casing, a flap extending from the casing and being adapted to be inserted into a nostril of a patient, a bottom cap, wherein the casing and the bottom cap define a space, and a fill material disposed in the space defined by the casing and the bottom cap, wherein the casing is structured to deform and conform to a shape of a portion of the nostril when the nostril applies pressure to the casing.

0012In another embodiment, a nasal prong for a cushion member adapted for use with a patient interface device is provided, The nasal prong includes a casing, a first flap extending from the casing and being adapted to be inserted into a nostril of a patient, a bottom cap, wherein the casing and the bottom cap define a space, a fill material disposed in the space defined by the casing and the bottom cap, and a second flap disposed between the casing and the nostril of the patient, wherein the casing is structured to deform and conform to a shape of a portion of the nostril and press against the second flap when the nostril applies pressure to the casing causing the second flap to conform to and to form a seal with the nostril of the patient.

0013These 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

0014<figref idref="DRAWINGS">FIG. 1</figref> is a perspective view of a patient interface device in accordance with an embodiment of the disclosed concept;

0015<figref idref="DRAWINGS">FIG. 2</figref> is a cross-sectional view of a cushion member of the patient interface device of <figref idref="DRAWINGS">FIG. 1</figref>;

0016<figref idref="DRAWINGS">FIGS. 3A and 3B</figref> are additional cross-sectional views of the cushion member of <figref idref="DRAWINGS">FIG. 2</figref>;

0017<figref idref="DRAWINGS">FIGS. 4A-4F</figref> are cross-sectional views of a nasal prong in accordance with an embodiment of the disclosed concept;

0018<figref idref="DRAWINGS">FIGS. 5A and 5B</figref> are cross-sectional views of a nasal prong in accordance with another embodiment of the disclosed concept;

0019<figref idref="DRAWINGS">FIGS. 6A and 6B</figref> are cross-sectional views of a nasal prong in accordance with another embodiment of the disclosed concept;

0020<figref idref="DRAWINGS">FIG. 7</figref> is a cross-sectional view of a nasal prong in accordance with another embodiment of the disclosed concept;

0021<figref idref="DRAWINGS">FIG. 8</figref> is a perspective view of a bottom side of a cushion of the patient interface device of <figref idref="DRAWINGS">FIG. 1</figref>;

0022<figref idref="DRAWINGS">FIG. 9</figref> is a perspective view of a top side of the cushion of the patient interface device of <figref idref="DRAWINGS">FIG. 1</figref>;

0023<figref idref="DRAWINGS">FIG. 10</figref> is a top view of a patient interface portion in accordance with an embodiment of the disclosed concept; and

0024<figref idref="DRAWINGS">FIG. 11</figref> is a cross-sectional view of a cushion in accordance with another exemplary embodiment of the disclosed concept.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

0025As used herein, the singular form of “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise. As used herein, the statement that two or more parts or components are “coupled” shall mean that the parts are joined or operate together either directly or indirectly, i.e., through one or more intermediate parts or components, so long as a link occurs. As used herein, “directly coupled” means that two elements are directly in contact with each other. As used herein, “fixedly coupled” or “fixed” means that two components are coupled so as to move as one while maintaining a constant orientation relative to each other.

0026Directional 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.

0027A system <b>2</b> adapted to provide a regimen of respiratory therapy to a patient according to one exemplary embodiment of the invention is generally shown in <figref idref="DRAWINGS">FIG. 1</figref>. System <b>2</b> includes a pressure generating device <b>4</b>, a delivery conduit <b>6</b>, and a patient interface device <b>8</b> including an elbow conduit <b>10</b>. Pressure generating device <b>4</b> is structured to generate a flow of breathing gas and may include, without limitation, ventilators, constant pressure support devices (such as a continuous positive airway pressure device, or CPAP device), variable pressure devices (e.g., BiPAP®, Bi-Flex®, or C-Flex™ devices manufactured and distributed by Philips Respironics of Murrysville, Pa.), and auto-titration pressure support devices. Delivery conduit <b>6</b> is structured to communicate the flow of breathing gas from pressure generating device <b>4</b> to patient interface device <b>8</b>. Delivery conduit <b>6</b> and patient interface device <b>8</b> are typically collectively referred to as a patient circuit.

0028In the present embodiment (described in detail herein), patient interface device <b>8</b> comprises a pillows style nasal cushion having nasal prongs that are received within the patient's nares in order to deliver breathing gas to the airway of the patient through the patient's nose. In the exemplary embodiment shown in <figref idref="DRAWINGS">FIG. 1</figref>, patient interface device <b>8</b> includes a cushion member <b>12</b> and a frame member <b>14</b> having a faceplate portion <b>16</b> and arms <b>18</b><i>a </i>and <b>18</b><i>b</i>. Cushion member <b>12</b> is coupled to a rear side of frame member <b>14</b>.

0029Frame member <b>14</b> is made of a rigid or semi-rigid material, such as, without limitation, an injection molded thermoplastic or silicone. Straps (not shown) of a headgear component may be attached to arms <b>18</b><i>a </i>and <b>18</b><i>b </i>to secure patient interface device <b>8</b> to the patient's head. An opening <b>20</b> in faceplate portion <b>16</b> to which elbow conduit <b>10</b> is coupled allows the flow of breathing gas from pressure generating device <b>4</b> to be communicated to an interior space defined by cushion member <b>12</b>, and then, to the airway of a patient. Opening <b>20</b> in faceplate portion <b>16</b> also allows the flow of exhalation gas (from the airway of such a patient) to be communicated to exhaust vent <b>22</b> provided in elbow conduit <b>10</b>.

0030As seen in <figref idref="DRAWINGS">FIG. 1</figref>, cushion member <b>12</b> includes a main body portion <b>24</b> and two nasal prongs <b>26</b><i>a</i>,<b>26</b><i>b </i>coupled to main body portion <b>24</b>. The structure of nasal prongs <b>26</b><i>a</i>,<b>26</b><i>b </i>and main body portion <b>24</b> will be discussed in further detail below in conjunction with a number of exemplary embodiments of the disclosed concept.

0031<figref idref="DRAWINGS">FIG. 2</figref> illustrates a cross-section of cushion member <b>12</b> according to an exemplary embodiment. Referring to <figref idref="DRAWINGS">FIG. 2</figref>, cushion member <b>12</b> includes main body portion <b>24</b> that comprises a base <b>112</b>, two stems <b>114</b>, and two platforms <b>116</b> (only one such stem <b>114</b> and platform <b>116</b> is shown in the cross-section of <figref idref="DRAWINGS">FIG. 2</figref>). Base <b>112</b>, stems <b>114</b>, and platforms <b>116</b> are integrally formed together. Main body portion <b>24</b> of cushion member <b>12</b> can be made from any suitable material, such as gel, silicone, foam, rubber, or a combination of materials. Nasal prongs <b>26</b><i>a</i>,<b>26</b><i>b </i>are coupled to corresponding platforms <b>116</b> of cushion member <b>12</b>.

0032Apertures formed by nasal prongs <b>26</b><i>a</i>,<b>26</b><i>b </i>allow air to flow from a patient into a chamber formed inside cushion member <b>12</b>. Air flow between the hollow area inside cushion member <b>12</b> and delivery conduit <b>6</b> is facilitated by an opening <b>111</b> (see <figref idref="DRAWINGS">FIG. 7</figref>) formed in cushion member <b>12</b>.

0033Continuing to refer to <figref idref="DRAWINGS">FIG. 2</figref>, nasal prong <b>26</b> (<b>26</b><i>a </i>or <b>26</b><i>b</i>) includes a flap <b>132</b>, outer casing <b>134</b>, inner casing <b>136</b>, and bottom cap <b>138</b>. Flap <b>132</b>, outer casing <b>134</b>, inner casing <b>136</b>, and bottom cap <b>138</b> can each be made from any suitable material, such as gel, silicone, foam, rubber, or a combination of materials. In one exemplary embodiment, flap <b>132</b> is made from silicone. Flap <b>132</b> is adapted to be inserted into a nostril of the user. Outer casing <b>134</b> is disposed on an outer portion of nasal prong <b>26</b> and inner casing <b>136</b> is disposed on an inner portion of nasal prong <b>26</b>. Outer casing <b>134</b>, inner casing <b>136</b>, and bottom cap <b>138</b> form a space which is filled with a fill material <b>140</b>. Fill material <b>140</b> generally consists of a gel or other suitable material that generally conforms to the space formed by outer casing <b>134</b>, inner casing <b>136</b>, and bottom cap <b>138</b>.

0034Fill material <b>140</b> may be a viscoelastic material, such as a gel substance comprising a viscoelastic polyurethane polymer, or an elastic material. Fill material <b>140</b> may also be liquid or air. As used herein, the term viscoelastic material shall mean a material that exhibits both viscous and elastic characteristics when undergoing deformation, and as a result exhibits time dependent strain. A viscoelastic material will thus deform under the influence of an applied stress, and when the stress is removed from the material, the material will slowly and not instantaneously recover from at least a portion of the deformation. As used herein, the term elastic material shall mean a material that exhibits elastic but not viscous characteristics when undergoing deformation. Elastic materials deform under the influence of an applied stress and return instantaneously to their original state once the stress is removed, thereby recovering from all of the deformation.

0035Cushion member <b>12</b> is adapted such that when the user wears patient interface device <b>8</b>, the user's nostril presses against outer casing <b>134</b>. In turn, interaction between base <b>112</b> and stem <b>114</b> creates a spring force which presses nasal prong <b>26</b> back against the user's nostril. The amount of spring force generated increases the further stems <b>114</b> are depressed into base <b>112</b>. Base <b>112</b> and stems <b>114</b> generate a spring force in a range of about 20 to 250 grams. The spring force assists with allowing nasal prong <b>26</b> to conform to the user's nostril and create a seal.

0036In some embodiments of the disclosed concept, base <b>112</b> and stems <b>114</b> have a durometer in a range of about 10 shA to 50 shA. Referring now to <figref idref="DRAWINGS">FIGS. 3A and 3B</figref>, the variable thickness of base <b>112</b> and stems <b>114</b> is described in more detail. For purposes of illustration, base <b>112</b> and stems <b>114</b> are divided into a first region <b>113</b> and a second region <b>115</b>. First region <b>113</b> begins at an end of stems <b>114</b> adjacent to platforms <b>116</b> and extends partially into base <b>112</b>. The remaining portion of base <b>112</b> forms second region <b>115</b>. First region <b>113</b> is thinnest in the area adjacent to platforms <b>116</b> and thickest in the area adjacent to second region <b>115</b>. In some embodiments of the disclosed concept, the thicknesses of cushion member <b>12</b> in first region <b>113</b> are within a range of about 0.4-1.8 mm thick. In some embodiments of the disclosed concept, the thicknesses of cushion member <b>12</b> in second region <b>115</b> are within a range of about 0.8-5.0 mm thick.

0037Cushion member <b>12</b> incorporates an arched structure that transfers compressive load through its sidewalls to its outside perimeter and away from sensitive areas of the user's philtrum and septum as well as away from the airpath through cushion member <b>12</b>. Greater thicknesses in second region <b>115</b> provides structural support for cushion member <b>12</b> which increases resistance to a complete collapse of cushion member <b>12</b>. A complete collapse of cushion member <b>12</b> happens when stem <b>114</b> collapses into base <b>112</b> far enough to block airflow through cushion member <b>12</b>. Thicknesses of the walls of cushion member <b>12</b> gradually decrease from in the direction from second region <b>115</b> to first region <b>113</b> which avoids an abrupt transition in the modulus of cushion member <b>12</b>. The gradual transition in thicknesses mitigates the potential for pressure points and aids in controlling conformance of cushion member <b>12</b>. The transition to thinner walls also helps enhance the stability of cushion member <b>12</b>.

0038Referring back to <figref idref="DRAWINGS">FIG. 2</figref>, a depression <b>142</b> is formed in an area of outer casing <b>134</b>. Depression <b>142</b> is operable to facilitate deformation of outer casing <b>134</b> allowing to conform to a shape of the user's nostril when pressure is applied to outer casing <b>134</b> by the user's nostril, as will be described in more detail hereinafter with respect to <figref idref="DRAWINGS">FIGS. 4A and 4B</figref>.

0039<figref idref="DRAWINGS">FIGS. 4A and 4B</figref> illustrate cross-sections of a nasal prong <b>26</b> in accordance with an embodiment of the disclosed concept. In <figref idref="DRAWINGS">FIG. 4A</figref>, nasal prong <b>26</b> is illustrated when a nostril <b>50</b> of a user is not applying pressure to nasal prong <b>26</b>. In <figref idref="DRAWINGS">FIG. 4B</figref>, nostril <b>50</b> is applying pressure to the nasal prong <b>26</b>, such as, for example, when the user is wearing patient interface device <b>8</b>.

0040Referring to <figref idref="DRAWINGS">FIG. 4A</figref>, depression <b>142</b> is formed in an area of outer casing <b>134</b> adjacent to an area where the nostril <b>50</b> applies pressure to outer casing <b>134</b>. Depression <b>142</b> may be, for example and without limitation, a sink or divot formed in outer casing <b>134</b> which makes outer casing <b>134</b>. Depression <b>142</b> increases the perimeter of the space formed by outer casing <b>134</b>, inner casing <b>136</b>, and bottom cap <b>138</b> relative to its cross-sectional area, which increases the ability of the outer casing <b>134</b> deform when pressure is applied to it without immediately putting it in tension. In contrast, if the outer casing <b>134</b>, inner casing <b>136</b>, and bottom cap <b>138</b> formed a semi-circular shape which minimized the perimeter of the space with respect to its cross-sectional area, the outer casing <b>134</b> would be resistant to deformation and would be immediately put in tension when pressure is applied to it.

0041Turning now to <figref idref="DRAWINGS">FIG. 4B</figref>, nostril <b>50</b> is applying pressure to nasal prong <b>26</b>, and more specifically, to outer casing <b>134</b>. As shown in <figref idref="DRAWINGS">FIG. 4B</figref>, outer casing <b>134</b> deforms and conforms to the shape of nostril <b>50</b> when nostril <b>50</b> applies pressure. In more detail, outer casing <b>134</b> collapses in the area where nostril <b>50</b> applies pressure, which causes a portion of fill material <b>140</b> to be displaced. Outer casing <b>134</b> expands in the area of depression <b>142</b> to accommodate the displaced fill material <b>140</b>. By collapsing in the area where nostril <b>50</b> applies pressure and expanding in the adjacent area where depression <b>142</b> is formed, outer casing <b>134</b> conforms to the shape of nostril <b>50</b>, as shown in <figref idref="DRAWINGS">FIG. 4B</figref>, thereby creating an improved seal between nasal prong <b>26</b> and nostril <b>50</b>.

0042Nostrils <b>50</b> of users can vary in size and shape, as well as where they apply pressure to outer casing <b>134</b>. The amount of pressure applied by nostril <b>50</b> can also vary. These variations can change the manner in which outer casing <b>134</b> deforms. Despite these variations, outer casing <b>134</b> deforms to conform to the shape of nostril <b>50</b> and forms a seal with nostril <b>50</b>. For example, <figref idref="DRAWINGS">FIGS. 4C-F</figref> illustrate alternative styles of deformation of outer casing <b>134</b>. Referring to <figref idref="DRAWINGS">FIGS. 4C and 4D</figref>, nostril <b>50</b> applies pressure to the area of outer casing <b>134</b> where depression <b>142</b> is formed. Depression <b>142</b> becomes a pocket for nostril <b>50</b> to sit in and outer casing <b>134</b> deforms to conform to the shape of inner and outer sides of nostril <b>50</b>, as shown in <figref idref="DRAWINGS">FIG. 4D</figref>. Referring to <figref idref="DRAWINGS">FIGS. 4E and 4F</figref>, nostril <b>50</b> applies pressure to an area just outside depression <b>142</b>. In response, outer casing <b>134</b> deforms to conform to the shape of inner and outer sides of nostril <b>50</b>, as shown in <figref idref="DRAWINGS">FIG. 4F</figref>.

0043<figref idref="DRAWINGS">FIGS. 5A and 5B</figref> illustrate cross-sections of a nasal prong <b>26</b>′ in accordance with an alternative exemplary embodiment of the disclosed concept. It will be appreciated by those having ordinary skill in the art that nasal prong <b>26</b>′ may be adapted for use with patient interface device <b>8</b> without departing from the scope of the disclosed concept. In <figref idref="DRAWINGS">FIG. 5A</figref> nasal prong <b>26</b>′ is illustrated when nostril <b>50</b> is not applying pressure to nasal prong <b>26</b>′. In <figref idref="DRAWINGS">FIG. 4B</figref>, nostril <b>50</b> is applying pressure to nasal prong <b>26</b>′.

0044Referring to <figref idref="DRAWINGS">FIG. 5A</figref>, depression <b>142</b>′ is formed in an area of inner casing <b>136</b>′ adjacent to an area of outer casing <b>134</b>′ that nostril <b>50</b> will apply pressure to. Depression <b>142</b>′ may be, for example and without limitation, a sink or divot formed in inner casing <b>136</b>′ which makes inner casing <b>136</b>′.

0045Turning now to <figref idref="DRAWINGS">FIG. 5B</figref>, nostril <b>50</b> is applying pressure to nasal prong <b>26</b>′, and more specifically, to an area of outer casing <b>134</b>′. As shown in <figref idref="DRAWINGS">FIG. 5B</figref>, outer casing <b>134</b>′ deforms by collapsing in the area where nostril <b>50</b> applies pressure, which causes a portion of fill material <b>140</b> to be displaced. Inner casing <b>136</b>′ expands in the area of depression <b>142</b>′ to accommodate the displaced fill material <b>140</b>. By collapsing in the area where nostril <b>50</b> applies pressure, outer casing <b>134</b>′ conforms to the shape of nostril <b>50</b>. Inner casing <b>136</b>′ also conforms to the shape of nostril <b>50</b> and presses against flap <b>132</b>′ causing flap <b>132</b>′ to also conform to the shape of nostril <b>50</b>, thereby creating an improved seal between nasal prong <b>26</b>′ and nostril <b>50</b>.

0046<figref idref="DRAWINGS">FIGS. 6A and 6B</figref> illustrate cross-sections of a nasal prong <b>26</b>″ in accordance with yet another alternative exemplary embodiment of the disclosed concept. It will be appreciated by those having ordinary skill in the art that nasal prong <b>26</b>″ may be adapted for use with patient interface device <b>8</b> without departing from the scope of the disclosed concept. In <figref idref="DRAWINGS">FIG. 6A</figref> nasal prong <b>26</b>″ is illustrated when nostril <b>50</b> is not applying pressure to nasal prong <b>26</b>″. In <figref idref="DRAWINGS">FIG. 6B</figref>, nostril <b>50</b> is applying pressure to nasal prong <b>26</b>″.

0047Referring to <figref idref="DRAWINGS">FIG. 6A</figref>, nasal prong <b>26</b>″ includes a second flap <b>144</b> formed between outer casing <b>134</b>″ and nostril <b>50</b>. In one particular embodiment, second flap <b>144</b> is made of silicone, but it is appreciated that second flap <b>144</b> may be made of any suitable material without departing from the scope of the disclosed concept. Depression <b>142</b>″ is formed in an area of outer casing <b>134</b>″ adjacent to an area where nostril <b>50</b> will apply pressure. Depression <b>142</b>″ may be, for example and without limitation, a sink or divot formed in outer casing <b>134</b>″ which makes outer casing <b>134</b>″.

0048Turning now to <figref idref="DRAWINGS">FIG. 6B</figref>, nostril <b>50</b> is applying pressure to nasal prong <b>26</b>″, and more specifically, to outer casing <b>134</b>″ through second flap <b>144</b>. As shown in <figref idref="DRAWINGS">FIG. 6B</figref>, second flap <b>144</b> is pressed by nostril <b>50</b> against outer casing <b>134</b>″ causing outer casing <b>134</b>″ to deform by collapsing in the area where pressure is applied, thus causing a portion of fill material <b>140</b> to be displaced. In the area of depression <b>142</b>″, outer casing <b>134</b>″ expands to accommodate the displaced fill material <b>140</b>. The expansion of outer casing <b>134</b>″ in the area of depression <b>142</b>″ causes outer casing <b>134</b>″ to conform to the shape of nostril <b>50</b> and to press against second flap <b>144</b> and cause second flap <b>144</b> to conform to the shape of nostril <b>50</b>, thereby creating an improved seal between nasal prong <b>26</b>″ and nostril <b>50</b>.

0049While nasal prongs <b>26</b>,<b>26</b>′,<b>26</b>″ include depressions <b>142</b>,<b>142</b>′,<b>142</b>″, it will also be appreciated by one having ordinary skill in the art that other variations in geometry may be used to increase the perimeter of the spaces defined by outer casing <b>134</b>,<b>134</b>′,<b>134</b>″, inner casing <b>136</b>,<b>136</b>′,<b>136</b>″, and bottom caps <b>138</b>,<b>138</b>′,<b>138</b>″ relative to their cross-sectional areas to increase the deformability of the outer casings <b>134</b>,<b>134</b>′,<b>134</b>″ without departing from the scope of the disclosed concept.

0050<figref idref="DRAWINGS">FIG. 7</figref> illustrates a cross section of a portion of a nasal prong <b>26</b>′″ in accordance with another embodiment of the disclosed concept. It will be appreciated by those having ordinary skill in the art that nasal prong <b>26</b>″ may be adapted for use with patient interface device <b>8</b> without departing from the scope of the disclosed concept. Inner casing <b>136</b>′″ and/or outer casing <b>134</b>′″ of nasal prong <b>26</b>′″ are formed of a material that can be elongated under tension. When nostril <b>50</b> applies pressure to outer casing <b>134</b>′″, outer casing <b>134</b>′″ deforms to conform to the shape of nostril <b>50</b> to form a seal with nostril <b>50</b>. Inner casing <b>136</b>′″ and/or outer casing <b>134</b>′″ elongate to accommodate fill material <b>140</b> displaced due to the deformation. As such, outer casing <b>134</b>′″ is able to conform to the shape of and form a seal with nostril <b>50</b> without having a depression formed therein.

0051Variations in thickness of inner casing <b>136</b>′″ and outer casing <b>134</b>′″ influence where deformation occurs as well as provide structural support. For example, inner casing <b>136</b>′″ and outer casing <b>134</b>′″ are divided into regions A, B, C, and D. Region A is the thinnest and deformation is most likely to occur in region A. Regions B and D are slightly thicker than Region A. Region C is thickest and provides structural support to outer casing <b>134</b>′″. In some embodiments, the thickness of Region A is in a range of about 0.2-0.3 mm, the thickness of Regions B and D are in a range of about 0.2-0.4 mm, and the thickness of Region C is in a range of about 0.4-0.6 mm. It will be appreciated by one having ordinary skill in the art that variations in thickness can also be applied to any of nasal prongs <b>26</b>,<b>26</b>′,<b>26</b>″ without departing from the scope of the disclosed concept.

0052<figref idref="DRAWINGS">FIG. 8</figref> is a view illustrating a bottom side of cushion member <b>12</b>. The bottom side of cushion member <b>12</b> is adapted to conform to and rest on the user's upper lip when the user wears patient interface device <b>8</b>. To facilitate resting on the user's upper lip, cushion member <b>12</b> includes upper lip contacting portions <b>118</b> and upper lip relief portion <b>120</b>. Cushion member <b>12</b> is adapted such that upper lip contacting portions <b>118</b> contact the user's upper lip in areas outside the middle area of the user's upper lip. Upper relief portion <b>120</b> is curved to relieve pressure applied to the middle area of the user's upper lip and conforms to the user's Philtrum (i.e., the section between the upper lip and Septum). The middle area of the upper lip is a more sensitive area of the upper lip, and relieving pressure to this area increases comfort for the user. The conformance of the cushion member <b>12</b> also provides a low profile design that contours to the user and increases stability. The conformance of cushion member <b>12</b> to the user's upper lip further aids, in conjunction with the variations in thickness of cushion member <b>12</b> previously described, in preventing cushion member <b>12</b> from collapsing and blocking the air path through cushion member <b>12</b> when the user tightens the headgear assembly on patient interface device <b>8</b>.

0053In some embodiments of the disclosed concept, upper lip contacting portions <b>118</b> and upper lip relief portion <b>120</b> are thinner than other areas of cushion member <b>12</b>. The thinner thickness of upper lip contacting portions <b>118</b> and upper lip relief portion <b>120</b> provide additional comfort for the user by having more compliance in the structure, which is thinner, thereby decreasing modulus and allowing it to be more flexible.

0054<figref idref="DRAWINGS">FIG. 9</figref> is a view illustrating a top side of cushion member <b>12</b>. The top side of cushion member <b>12</b> is disposed near the tip of the user's nose when the user wears patient interface device <b>8</b>. The tip of the user's nose is a sensitive area and undue pressure can cause discomfort for the user. The top side of cushion member <b>12</b> includes a nose relief portion <b>122</b> which is curved so as to prevent or relieve the pressure applied to the user's nose, thus increasing the user's comfort.

0055<figref idref="DRAWINGS">FIG. 10</figref> illustrates a top view of cushion member <b>12</b>. In <figref idref="DRAWINGS">FIG. 8</figref>, D<b>1</b> is a distance between the centers of the tips of nasal prongs <b>26</b><i>a</i>,<b>26</b><i>b </i>(nasal prong <b>26</b><i>b </i>is not shown in <figref idref="DRAWINGS">FIG. 10</figref>). In some embodiments of the disclosed concept, D<b>1</b> is in a range of about 15-20 mm, and is preferably selected from one of about 16 mm, 17.5 mm, 19.5 mm D<b>2</b> is a distance between the centers of the tips of platforms <b>416</b>. In some embodiments of the disclosed concept, D<b>2</b> is in a range of about 20-25 mm, and is preferably selected from one of about 20.5 mm, 22 mm, and 24 mm D<b>3</b> is a height of nasal prongs <b>26</b><i>a</i>,<b>26</b><i>b</i>. In some embodiments of the disclosed concept, D<b>3</b> is in a range of about 9-12 mm, and is preferably about 10.6 mm D<b>4</b> is a height of stem <b>114</b>. In some embodiments of the disclosed concept, D<b>4</b> is in a range of about 2-4 mm, and is preferably about 3 mm. θ₁is an angle between an axis of one of nasal prongs <b>26</b><i>a</i>,<b>26</b><i>b </i>and a line parallel to a center line of cushion member <b>12</b>. In some embodiments of the disclosed concept, θ₁is in a range of about 20-24°, and is preferably about 22°. In some embodiments of the disclosed concept, the overall stem height (i.e., a distance from the base of the stem to the tip of the nasal prong <b>26</b><i>a </i>or <b>26</b><i>b</i>) is in a range of about 14-16 mm, and is preferably about 15.1 mm.

0056<figref idref="DRAWINGS">FIG. 11</figref> illustrates a side view of cushion member <b>12</b>′ in accordance with an exemplary embodiment of the disclosed concept. Cushion member <b>12</b>′ includes a first portion <b>124</b> made of a first material (e.g., without limitation, silicone having a durometer of about 75 shA) and a second portion <b>126</b> made of a second material (e.g., without limitation, silicone having a durometer of about 20 shA). The durometer of the first material is higher than the durometer of the second material. First portion <b>124</b> of cushion member <b>12</b>′ forms a portion of cushion member <b>12</b>′ that couples to frame member <b>14</b>. Using a higher durometer material for first portion <b>124</b> of cushion member <b>12</b>′ allows for better audible and tactile feedback during assembly of patient interface device <b>8</b> which makes it more obvious to the user when cushion member <b>12</b>′ and frame member <b>14</b> are properly coupled together. The higher durometer material also creates a more robust seal between cushion member <b>12</b>′ and frame member <b>14</b>. Furthermore, the higher durometer material helps opening <b>111</b> of cushion member <b>12</b>′ retain its shape. Opening <b>111</b> may have a distinctive shape, such as, for example, a triangle, which only allows cushion member <b>12</b>′ and frame member <b>14</b> to be coupled when they are properly aligned with each other.

0057Second portion <b>126</b> of cushion member <b>12</b>′ forms a portion of cushion member <b>12</b>′ that contacts the user's face. Using a lower durometer material for second portion <b>126</b> of cushion member <b>12</b>′ provides increased comfort for the user and also allows cushion member <b>12</b>′ to better conform to the user's face such as, for example, during static and dynamic moments of sleep.

0058Cushion member <b>12</b>′ having materials with different durometers may be manufactured using any suitable method without departing from the scope of the disclosed concept. In one example, the higher durometer portion of the cushion member <b>12</b>′ is molded first and then the lower durometer portion of cushion member <b>12</b>′ is overmolded onto the higher durometer portion. In another example, both the higher durometer and lower durometer portions of cushion member <b>12</b>′ are simultaneously formed using a two-shot molding process.

0059In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word “comprising” or “including” does not exclude the presence of elements or steps other than those listed in a claim. In a device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The word “a” or “an” preceding an element does not exclude the presence of a plurality of such elements. In any device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain elements are recited in mutually different dependent claims does not indicate that these elements cannot be used in combination.

0060Although 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.