Patent Description:
The present invention pertains to airway pressure support systems for use in delivering a flow of a humidified gas to the airway of a patient. The present invention also relates to patient interface devices for airway pressure support systems, and headgear assemblies for the same.

Many individuals suffer from disordered breathing during sleep. Sleep apnea is a common example of such sleep disordered breathing suffered by millions of people throughout the world. One type of sleep apnea is obstructive sleep apnea (OSA), which is a condition in which sleep is repeatedly interrupted by an inability to breathe due to an obstruction of the airway; typically the upper airway or pharyngeal area. Obstruction of the airway is generally believed to be due, at least in part, to a general relaxation of the muscles which stabilize the upper airway segment, thereby allowing the tissues to collapse the airway. Another type of sleep apnea syndrome is a central apnea, which is a cessation of respiration due to the absence of respiratory signals from the brain's respiratory center. An apnea condition, whether obstructive, central, or mixed, which is a combination of obstructive and central, is defined as the complete or near cessation of breathing, for example a <NUM>% or greater reduction in peak respiratory airflow.

Those afflicted with sleep apnea experience sleep fragmentation and complete or nearly complete cessation of ventilation intermittently during sleep with potentially severe degrees of oxyhemoglobin desaturation. These symptoms may be translated clinically into extreme daytime sleepiness, cardiac arrhythmias, pulmonary-artery hypertension, congestive heart failure and/or cognitive dysfunction. Other consequences of sleep apnea include right ventricular dysfunction, carbon dioxide retention during wakefulness, as well as during sleep, and continuous reduced arterial oxygen tension. Sleep apnea sufferers may be at risk for excessive mortality from these factors as well as by an elevated risk for accidents while driving and/or operating potentially dangerous equipment.

Even if a patient does not suffer from a complete or nearly complete obstruction of the airway, it is also known that adverse effects, such as arousals from sleep, can occur where there is only a partial obstruction of the airway. Partial obstruction of the airway typically results in shallow breathing referred to as a hypopnea. A hypopnea is typically defined as a <NUM>% or greater reduction in the peak respiratory airflow. Other types of sleep disordered breathing include, without limitation, upper airway resistance syndrome (UARS) and vibration of the airway, such as vibration of the pharyngeal wall, commonly referred to as snoring.

It is well known to treat sleep disordered breathing by applying a continuous positive air pressure (CPAP) to the patient's airway. This positive pressure effectively "splints" the airway, thereby maintaining an open passage to the lungs. It is also known to provide a positive pressure therapy in which the pressure of gas delivered to the patient varies with the patient's breathing cycle, or varies with the patient's breathing effort, to increase the comfort to the patient. This pressure support technique is referred to as bi-level pressure support, in which the inspiratory positive airway pressure (IPAP) delivered to the patient is higher than the expiratory positive airway pressure (EPAP). It is further known to provide a positive pressure therapy in which the pressure is automatically adjusted based on the detected conditions of the patient, such as whether the patient is experiencing an apnea and/or hypopnea. This pressure support technique is referred to as an auto-titration type of pressure support, because the pressure support device seeks to provide a pressure to the patient that is only as high as necessary to treat the disordered breathing. United States patent application <CIT> discloses a patient interface that seals a user's face by providing an oral-nasal mask that includes an integrated nasal interface. United States patent application <CIT> discloses a nasal assembly for delivering breathable gas to a patient. United States patent application <CIT> discloses a headgear for a respiratory mask which has first and second straps configured to be connected to each other by first and second buckles. <CIT> discloses a respiratory mask having a frame supporting a sealing arrangement.

Pressure support therapies as just described involve the placement of a patient interface device including a mask component having a soft, flexible sealing cushion on the face of the patient. The mask component may be, without limitation, a nasal mask that covers the patient's nose, a nasal/oral mask that covers the patient's nose and mouth, or a full face mask that covers the patient's face. Such patient interface devices may also employ other patient contacting components, such as forehead supports, cheek pads and chin pads. The patient interface device is typically secured to the patient's head by a headgear component. The patient interface device is connected to a gas delivery tube or conduit and interfaces the pressure support device 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.

In order to secure the patient interface device to the head of the patient, many known patient interface devices include headgear assemblies. Some headgear assemblies include a single strap member which is coupled to opposing sides of a frame member of the patient interface device. The strap member typically extends around the back of the head of the patient in order to ensure that the cushion is pulled onto the patient at or about the patient's airway. One known problem with existing headgear assemblies is that the strap member often does not stay maintained on the head of the patient. Specifically, it is common that during use, such as while the patient is sleeping, the strap member may slide up the back of the head of the patient. In this situation, the forces that previously maintained engagement between the cushion and the patient would be significantly reduced, thus compromising the integrity of the pressure support therapy.

Accordingly, it is an object of the present invention to provide an improved airway pressure support system, and patient interface device and headgear assembly for the same.

According to the invention, a headgear assembly is provided for use in a patient interface having a frame member and a cushion for delivering a flow of a breathing gas to the airway of a patient, the frame member having a first rotation-resistant coupling and a second rotation-resistant coupling defined therein. The headgear assembly includes a first arm member and a second arm member, each arm member having a first end and a second end located opposite the first end, the first end of the first arm member having a structure sized and configured to selectively engage the first rotation-resistant coupling in a manner which prohibits rotation of the first arm member with respect to the frame member in a first plane in which the first arm member is located, and the first end of the second arm member having a structure sized and configured to selectively engage the second rotation-resistant coupling in a manner which prohibits rotation of the second arm member with respect to the frame member in a second plane in which the second arm member is located; and a strap member coupled to the first arm member and the second arm member, and extending between the second end of the first arm member and the second end of the second arm member.

In accordance with another aspect of the disclosed concept, a patient interface device is provided for an airway pressure support system. The airway pressure support system has a hose and a gas flow generator configured to generate a flow of breathing gas. The patient interface device includes a cushion configured to receive the flow of breathing gas and deliver the flow of breathing gas to an airway of a patient; a frame member coupled to the cushion; a coupling member coupled to the frame member and structured to be coupled to the hose in order to communicate the flow of breathing gas from the gas flow generator to the frame member, the coupling member being fluidly coupled to and located opposite and distal the cushion; and a headgear assembly having a first arm member and a second arm member each including a first end and a second end located opposite the first end, each respective first end being directly coupled to the frame member, and a strap member coupled to the first arm member and the second arm member and extending therebetween. Each respective first end is located closer to the coupling member than each respective second end and the strap member.

In accordance with another aspect of the disclosed concept, an airway pressure support system includes a hose, a gas flow generator configured to generate a flow of breathing gas, and the aforementioned patient interface device.

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.

As 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 joined or coupled together directly and are 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.

As used herein, the word "unitary" means a component is created as a single piece or unit. That is, a component that includes pieces that are created separately and then coupled together as a unit is not a "unitary" component or body. As used herein, the statement that two or more parts or components "engage" one another shall mean that the parts exert a force against one another either directly or through one or more intermediate parts or components. As used herein, the term "number" shall mean one or an integer greater than one (i.e., a plurality).

<FIG> is a side elevation view of an airway pressure support system <NUM> and patient interface device <NUM> for the same, in accordance with one non-limiting embodiment of the disclosed concept. Pressure support system <NUM> further includes a hose <NUM> (shown in simplified form) and a gas flow generator <NUM> (shown in simplified form). In operation, gas flow generator <NUM> is configured to generate a flow of breathing gas, which, via hose <NUM>, is passed into patient interface device <NUM>.

Patient interface device <NUM> includes a cushion <NUM>, a frame member <NUM> coupled to cushion <NUM>, and a coupling member (e.g., without limitation, elbow <NUM>) coupled to frame member <NUM>. It will be appreciated that elbow <NUM> is coupled to hose <NUM> in order to communicate the flow of breathing gas from gas flow generator <NUM> to frame member <NUM>. As frame member <NUM> preferably defines a fluid pathway configured to be disposed on opposing sides of the head of patient <NUM>, it follows that frame member <NUM> fluidly couples elbow <NUM> to cushion <NUM>. Stated differently, elbow <NUM> is fluidly coupled to and located opposite and distal cushion <NUM>. In this manner, cushion <NUM> is able to deliver the flow of breathing gas to the airway of patient <NUM>.

In accordance with the disclosed concept, patient interface device <NUM> further includes a novel headgear assembly <NUM> configured to minimize and/or eliminate the possibility that a strap will slip off of the head of patient <NUM> while therapy is being delivered. Referring to <FIG>, headgear assembly <NUM> includes a first arm member <NUM>, a second arm member <NUM> located opposite first arm member <NUM>, and a strap member <NUM>. Each arm member <NUM>, <NUM> includes a first end <NUM>, <NUM>, a second end <NUM>, <NUM> located opposite first end <NUM>, <NUM>, and a body portion <NUM>, <NUM> extending in a curved manner between first end <NUM>, <NUM> and second <NUM>, <NUM>.

Specifically, second end <NUM> of first arm member <NUM> is spaced first and second distances from cushion <NUM> and elbow <NUM>, respectively. Second end <NUM> of second arm member <NUM> is spaced third and fourth distances from cushion <NUM> and elbow <NUM>, respectively. The first and third distances are the same, and the second and fourth distances are the same. As shown in <FIG>, arm members <NUM> (i.e., and second arm member <NUM>, not shown in <FIG>, but see <FIG>) are concave facing the corresponding ears of patient <NUM> such that second ends <NUM>, <NUM> are configured to be located at or about the same elevation as the base of the ears and behind the ears of patient <NUM>. In this manner, each of first ends <NUM>, <NUM> are preferably located closer to elbow <NUM> than second ends <NUM>, <NUM> and strap member <NUM>, the advantages of which will become more apparent below. Continuing to refer to <FIG>, cushion <NUM> has a first end portion <NUM> and a second end portion <NUM> located opposite and distal first end portion <NUM>. As shown, first and second end portions <NUM>,<NUM>, and first and second ends <NUM>, <NUM> are substantially located in a plane <NUM>. Furthermore, elbow <NUM> is located opposite and distal plane <NUM>.

First ends <NUM>,<NUM> of arm members <NUM>,<NUM> are preferably directly coupled to frame member <NUM>. <FIG> show one example embodiment of the disclosed concept wherein arm members <NUM>, <NUM> are removably coupled to frame member <NUM>. For example, as shown in <FIG> and <FIG>, frame member <NUM> has first and second rotation-resistant couplings (e.g., without limitation, elongated slots <NUM>, <NUM>). It will be appreciated that first end <NUM> has a structure (e.g., without limitation, a structure including a hook-shaped portion <NUM>) that is sized and configured to selectively engage first elongated slot <NUM> in a manner which prohibits rotation of first arm member <NUM> with respect to frame member <NUM> in a first plane in which first arm member <NUM> is located. Similarly, it will be appreciated that first end <NUM> of second arm member <NUM> has a structure (e.g., without limitation, a structure including a hook-shaped portion <NUM>) that is sized and configured to selectively engage second elongated slot <NUM> in a manner which prohibits rotation of second arm member <NUM> with respect to frame member <NUM> in a second plane in which second arm member <NUM> is located.

As a result of the aforementioned coupling between arm members <NUM>, <NUM> and frame member <NUM>, when patient interface device <NUM> is donned by patient <NUM>, second ends <NUM>, <NUM> are structured to be maintained behind and at the same elevation as the base of the ears of patient <NUM>. Referring again to <FIG>, strap member <NUM> is coupled, preferably adjustably coupled to second ends <NUM>, <NUM> of arm members <NUM>, <NUM> and extends therebetween. It will also be appreciated that suitable alternative strap members (not shown) may be non-adjustably coupled to arm members <NUM>, <NUM>, such as, without limitation, via a connection wherein the strap member is sewn onto second ends <NUM>, <NUM> of arm members <NUM>, <NUM>.

Furthermore, arm members <NUM>,<NUM> are preferably made of a material (e.g., without limitation, a thermoplastic material) that is more rigid and different than strap member <NUM>. Non-limiting examples of materials from which strap member <NUM> may be made include fabric, fabric/foam laminates, elastomers such as silicone and thermoplastic elastomers, elastic, and/or fabric-covered elastomers. In one example embodiment, arm members <NUM>, <NUM> each have a Young's modulus of greater than <NUM> Gigapascals, and a durometer of between <NUM> Shore A to <NUM> Shore D. Accordingly, when patient interface device <NUM> is donned by patient <NUM>, the relatively rigid arm members <NUM>, <NUM> also function to maintain strap member <NUM> in the position depicted in <FIG>. In this manner, it will be appreciated that potential upward movements of strap member <NUM> (from the perspective of <FIG>) will immediately be resisted by arm members <NUM>, <NUM>, specifically by the connection between arm members <NUM>, <NUM> and frame member <NUM>. Thus, headgear assembly <NUM> substantially minimizes and/or eliminates the likelihood that patient interface device <NUM> will slide off of the head of patient <NUM> when pressure support therapy is being delivered.

Additionally, as shown in <FIG>, such arrangement of arm members <NUM>,<NUM> positions strap member below the occipital bone <NUM> of patient <NUM> (as viewed when the patient's head is in an upright position such as shown in <FIG>) when patient interface device <NUM> is donned by patient <NUM>, thereby providing another mechanism to minimize and/or eliminate the likelihood that patient interface device <NUM> will slide off of the head of patient <NUM>. Specifically, strap member <NUM> is preferably located at the base of the head of patient <NUM> such that strap member <NUM> would have to flex a relatively large distance to pass by occipital bone <NUM>, which protrudes outwardly a significant distance from the head of patient <NUM>. Additionally, as shown in <FIG>, second end <NUM> of first arm member <NUM> is spaced a distance D from second end <NUM> of second arm member <NUM>, and strap member <NUM> has a length L. While strap member <NUM> may flex a bit when patient interface device <NUM> is donned by patient <NUM>, it will be appreciated that length L may preferably generally be the same as distance D. See also, for example, <FIG>, wherein it can be seen that strap member <NUM> is not structured to bow a significant amount, as compared to an arrangement wherein a different strap member might extend around the head of the patient above the occipital bone. In these arrangements the strap member is relatively long, and as a result are prone to slippage.

Continuing to refer to <FIG>, it will be appreciated that because of the position of second ends <NUM>, <NUM> with respect to the head of patient <NUM>, strap member <NUM> is configured to exert a force FS on the head of patient <NUM>. The resisting force generally includes a normal force component FN perpendicular to the head of patient <NUM>, and a friction force component FF parallel to the surface of the head of patient <NUM>. It will be appreciated with reference to <FIG> that force FS is perpendicular to or below (e.g., closer to the neck of patient <NUM>) normal force component FN. As a result, patient interface device <NUM> generally preferably does not rely on frictional forces between strap member <NUM> and patient <NUM> to be maintained on the head of patient <NUM>. Specifically, it can be appreciated that headgear assembly <NUM> is aligned so as to pull strap member <NUM> further down (with respect to the orientation of <FIG>) toward the neck of patient <NUM> rather than up toward the crown.

As stated above, first and second arm members <NUM>, <NUM> preferably have hook-shaped portions <NUM>, <NUM> sized to engage slots <NUM>,<NUM> of frame member <NUM>. Hook-shaped portions <NUM>, <NUM> each include respective intermediate portions <NUM>,<NUM> extending from and being located generally perpendicular to body portions <NUM>, <NUM>, and retaining portions <NUM>, <NUM> extending from and being located perpendicular to intermediate portions <NUM>, <NUM>. Hook-shaped portions <NUM>, <NUM> provide a mechanism by which first ends <NUM>, <NUM> can be removably coupled to frame member <NUM>, and provide a mechanism by which undesired rotation of arm members <NUM>, <NUM> can be resisted. Specifically, referring to <FIG>, if arm members <NUM> (e.g., and <NUM>, not shown in <FIG>) were to begin to rotate in the counterclockwise direction, the connection between hook-shaped portions <NUM>, <NUM> and frame member <NUM> would advantageously resist such rotation. In one example embodiment, intermediate portions <NUM>, <NUM> are sized to fill slots <NUM>,<NUM> and/or engage with the edges of frame member <NUM> defining said slots <NUM>, <NUM>.

<FIG> shows a right side elevation view of a portion of another patient interface device <NUM>, in accordance with another non-limiting embodiment of the disclosed concept. Patient interface device <NUM> has all of the same advantages as patient interface device <NUM>, and like reference numbers represent like elements. Additionally, as shown in <FIG>, first arm member <NUM> has a number of living hinges (three example living hinges <NUM>, <NUM>, <NUM>) located in body portion <NUM> between first and second ends <NUM>,<NUM>. Hinges <NUM>, <NUM>, <NUM> may be thinned or weakened regions of body portion <NUM>, and advantageously allow first arm member <NUM> to bend around the head of the patient while still resisting bending moments between frame member <NUM> a strap member (not shown in <FIG>, but see strap member <NUM> of patient interface device <NUM>, discussed above). While the disclosed concept has been described herein in association with first arm member <NUM> having hinges <NUM>, <NUM>, <NUM> to allow for the advantageous bending around the head of the patient, it will be appreciated that a suitable alternative arm member (not shown) may have slots in its body portion in addition to and/or instead of hinges, without departing from the scope of the disclosed concept. It will also be appreciated that a second arm member (not shown) opposing first arm member <NUM> may also have hinges and/or slots, or any suitable arrangement/structure which provides for lessor stiffness, in a similar manner as first arm member <NUM>, without departing from the scope of the disclosed concept.

<FIG> shows a side isometric view of a portion of another patient interface device <NUM>, in accordance with another non-limiting embodiment of the disclosed concept. Patient interface device <NUM> has all of the same advantages as patient interface devices <NUM>, <NUM>, and like reference numbers represent like elements. Additionally, patient interface device <NUM> is structured differently from patient interface devices <NUM>,<NUM>. Specifically, first ends <NUM>, <NUM> of arm members <NUM>, <NUM> are configured to be fixedly coupled to frame member <NUM>. First ends <NUM>, <NUM> may be coupled to frame member <NUM> by an overmolding procedure, a co-molding procedure, and/or via adhesives.

Accordingly, it will be appreciated that in each of patient interface devices <NUM>, <NUM>, <NUM>, when assembled, first arm members <NUM>, <NUM>, <NUM> and second arm members <NUM>, <NUM> are each generally fixed with respect to corresponding frame members <NUM>, <NUM>. As a result, and as stated above, the likelihood of any undesirable rotation of arm members <NUM>, <NUM>, <NUM>, <NUM>, <NUM> with respect to corresponding frame members <NUM>,<NUM> is significantly minimized.

It will be appreciated that the disclosed concept provides for an improved (e.g., without limitation, better protected against slippage (e.g., unintended sliding of strap members)) airway pressure support system <NUM>, and patient interface device <NUM>,<NUM>,<NUM> and headgear assembly <NUM> for the same, in which a strap member <NUM> is advantageously maintained at a base of the head of a patient <NUM>.

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.

Claim 1:
A headgear assembly (<NUM>) for use in a patient interface device (<NUM>, <NUM>) having a frame member (<NUM>) and a cushion (<NUM>) for delivering a flow of a breathing gas to the airway of a patient (<NUM>), the frame member having a first rotation-resistant coupling (<NUM>) and a second rotation-resistant coupling (<NUM>) defined therein, the headgear assembly comprising:
a first arm member (<NUM>, <NUM>) and a second arm member (<NUM>), each arm member comprising a first end (<NUM>, <NUM>, <NUM>) and a second end (<NUM>, <NUM>, <NUM>, <NUM>) disposed opposite the first end, the first end of the first arm member having a structure (<NUM>) sized and configured to selectively engage the first rotation-resistant coupling in a manner which prohibits rotation of the first arm member with respect to the frame member in a first plane in which the first arm member is disposed, and the first end of the second arm member having a structure (<NUM>) sized and configured to selectively engage the second rotation-resistant coupling in a manner which prohibits rotation of the second arm member with respect to the frame member in a second plane in which the second arm member is disposed; and
a strap member (<NUM>) coupled to the first arm member and the second arm member, and extending between each of the second end of the first arm member and the second end of the second arm member,
characterized in that each of the first arm member and the second arm member comprises a body portion (<NUM>, <NUM>) extending in a curved manner between the first end and the second end, each of the arm members being concave so as to face corresponding ears of the patient with the second ends being configured to be located at or about the same elevation as the base of the ears and behind the ears of the patient.