Patent ID: 12186484

5 DETAILED DESCRIPTION OF EXAMPLES OF THE TECHNOLOGY

Before the present technology is described in further detail, it is to be understood that the technology is not limited to the particular examples described herein, which may vary. It is also to be understood that the terminology used in this disclosure is for the purpose of describing only the particular examples discussed herein, and is not intended to be limiting.

The following description is provided in relation to various examples which may share one or more common characteristics and/or features. It is to be understood that one or more features of any one example may be combinable with one or more features of another example or other examples. In addition, any single feature or combination of features in any of the examples may constitute a further example.

5.1 Therapy

In one form, the present technology comprises a method for treating a respiratory disorder comprising the step of applying positive pressure to the entrance of the airways of a patient1000.

In certain examples of the present technology, a supply of air at positive pressure is provided to the nasal passages of the patient via one or both nares.

In certain examples of the present technology, mouth breathing is limited, restricted or prevented.

5.2 Treatment Systems

In one form, the present technology comprises an apparatus or device for treating a respiratory disorder. The apparatus or device may comprise an RPT device4000for supplying pressurised air to the patient1000via an air circuit4170to a patient interface3000.

5.3 Patient Interface

A non-invasive patient interface3000in accordance with one aspect of the present technology comprises the following functional aspects: a seal-forming structure3100, a plenum chamber3200, a positioning and stabilising structure3300, a vent3400, one form of connection port3600for connection to air circuit4170, and a forehead support3700. In some forms a functional aspect may be provided by one or more physical components. In some forms, one physical component may provide one or more functional aspects. In use the seal-forming structure3100is arranged to surround an entrance to the airways of the patient so as to facilitate the supply of air at positive pressure to the airways.

If a patient interface is unable to comfortably deliver a minimum level of positive pressure to the airways, the patient interface may be unsuitable for respiratory pressure therapy.

The patient interface3000in accordance with one form of the present technology is constructed and arranged to be able to provide a supply of air at a positive pressure of at least 6 cmH2O with respect to ambient.

The patient interface3000in accordance with one form of the present technology is constructed and arranged to be able to provide a supply of air at a positive pressure of at least 10 cmH2O with respect to ambient.

The patient interface3000in accordance with one form of the present technology is constructed and arranged to be able to provide a supply of air at a positive pressure of at least 20 cmH2O with respect to ambient.

5.3.1 Seal-Forming Structure

In one form of the present technology, a seal-forming structure3100provides a target seal-forming region, and may additionally provide a cushioning function. The target seal-forming region is a region on the seal-forming structure3100where sealing may occur. The region where sealing actually occurs—the actual sealing surface—may change within a given treatment session, from day to day, and from patient to patient, depending on a range of factors including for example, where the patient interface was placed on the face, tension in the positioning and stabilising structure and the shape of a patient's face.

In one form the target seal-forming region is located on an outside surface of the seal-forming structure3100.

In certain forms of the present technology, the seal-forming structure3100is constructed from a biocompatible material, e.g. silicone rubber.

A seal-forming structure3100in accordance with the present technology may be constructed from a soft, flexible, resilient material such as silicone.

In certain forms of the present technology, a system is provided comprising more than one a seal-forming structure3100, each being configured to correspond to a different size and/or shape range. For example the system may comprise one form of a seal-forming structure3100suitable for a large sized head, but not a small sized head and another suitable for a small sized head, but not a large sized head.

5.3.1.1 Sealing Mechanisms

In one form, the seal-forming structure includes a sealing flange utilizing a pressure assisted sealing mechanism. In use, the sealing flange can readily respond to a system positive pressure in the interior of the plenum chamber3200acting on its underside to urge it into tight sealing engagement with the face. The pressure assisted mechanism may act in conjunction with elastic tension in the positioning and stabilising structure.

In one form, the seal-forming structure3100comprises a sealing flange and a support flange. The sealing flange comprises a relatively thin member with a thickness of less than about 1 mm, for example about 0.25 mm to about 0.45 mm, which extends around the perimeter of the plenum chamber3200. Support flange may be relatively thicker than the sealing flange. The support flange is disposed between the sealing flange and the marginal edge of the plenum chamber3200, and extends at least part of the way around the perimeter. The support flange is or includes a spring-like element and functions to support the sealing flange from buckling in use.

In one form, the seal-forming structure may comprise a compression sealing portion or a gasket sealing portion. In use the compression sealing portion, or the gasket sealing portion is constructed and arranged to be in compression, e.g. as a result of elastic tension in the positioning and stabilising structure.

In one form, the seal-forming structure comprises a tension portion. In use, the tension portion is held in tension, e.g. by adjacent regions of the sealing flange.

In one form, the seal-forming structure comprises a region having a tacky or adhesive surface.

In certain forms of the present technology, a seal-forming structure may comprise one or more of a pressure-assisted sealing flange, a compression sealing portion, a gasket sealing portion, a tension portion, and a portion having a tacky or adhesive surface.

5.3.1.2 Nose Bridge or Nose Ridge Region

In one form, the non-invasive patient interface3000comprises a seal-forming structure that forms a seal in use on a nose bridge region or on a nose-ridge region of the patient's face.

In one form, the seal-forming structure includes a saddle-shaped region constructed to form a seal in use on a nose bridge region or on a nose-ridge region of the patient's face.

5.3.1.3 Upper Lip Region

In one form, the non-invasive patient interface3000comprises a seal-forming structure that forms a seal in use on an upper lip region (that is, the lip superior) of the patient's face.

In one form, the seal-forming structure includes a saddle-shaped region constructed to form a seal in use on an upper lip region of the patient's face.

5.3.1.4 Chin-Region

In one form the non-invasive patient interface3000comprises a seal-forming structure that forms a seal in use on a chin-region of the patient's face.

In one form, the seal-forming structure includes a saddle-shaped region constructed to form a seal in use on a chin-region of the patient's face.

5.3.1.5 Forehead Region

In one form, the seal-forming structure that forms a seal in use on a forehead region of the patient's face. In such a form, the plenum chamber may cover the eyes in use.

5.3.1.6 Nasal Pillows

In one form the seal-forming structure of the non-invasive patient interface3000comprises a pair of nasal puffs, or nasal pillows, each nasal puff or nasal pillow being constructed and arranged to form a seal with a respective naris of the nose of a patient.

Nasal pillows in accordance with an aspect of the present technology include: a frusto-cone, at least a portion of which forms a seal on an underside of the patient's nose, a stalk, a flexible region on the underside of the frusto-cone and connecting the frusto-cone to the stalk. In addition, the structure to which the nasal pillow of the present technology is connected includes a flexible region adjacent the base of the stalk. The flexible regions can act in concert to facilitate a universal joint structure that is accommodating of relative movement both displacement and angular of the frusto-cone and the structure to which the nasal pillow is connected. For example, the frusto-cone may be axially displaced towards the structure to which the stalk is connected.

5.3.1.7 Nasal Cradle

FIGS.16-28and67show a seal-forming structure3100according to a first example of the present technology.FIGS.22-28show the seal-forming structure3100with a plenum chamber3200, which will be described in greater detail below.FIGS.29-36and68show a seal-forming structure3100according to a second example of the present technology.FIGS.35and36show the seal-forming structure3100with a plenum chamber3200, which will be described in greater detail below.FIGS.37-44and69show a seal-forming structure3100according to a third example of the present technology.FIGS.43and44show the seal-forming structure3100with a plenum chamber3200, which will be described in greater detail below.FIGS.45-52and70show a seal-forming structure3100according to a fourth example of the present technology.FIGS.51and52show the seal-forming structure3100with a plenum chamber3200, which will be described in greater detail below. As can be seen in these views, the different examples are sized and shaped differently and, accordingly, each variation is intended provide an optimal fit for patients having noses and faces shaped and sized differently.FIGS.16-21,FIGS.29-34,FIGS.37-42, andFIGS.45-50include broken lines demarcating regions of different thickness, and it should be understood that these are only nominal boundaries, not actual structures.

The four examples of seal-forming structure3100described in the preceding paragraph may be considered nasal cradle cushions and are intended to provide a flow of pressurised gas to the patient's nares by sealing against at least the underside of the patient's nose. The exemplary seal-forming structures3100will engage the patient's face below the bridge of the nose and some examples, depending on the size and shape of the patient's nose, may engage the patient's nose below the pronasale. In other words, for example, the seal-forming structure3100may be structured3100so as not to engage the patient's nose superior to the pronasale. The exemplary seal-forming structures3100will also engage the patient's face at least above the upper vermillion. Thus, the exemplary seal-forming structures3100may seal against the patient's lip superior in use. Furthermore, the patient's mouth may remain uncovered by the seal-forming structure3100of the depicted examples such that the patient may breathe freely, i.e., directly to atmosphere, without interference from the seal-forming structure3100.

Examples of a nasal cradle cushion, e.g., the exemplary seal-forming structures disclosed herein, may include a superior saddle or concave region that has positive curvature across the cushion. Also, a nasal cradle cushion may be understood to have a single target seal forming region or surface, whereas a pillows cushion may have two target seal forming regions (one for each naris). Cradle cushions may also have a posterior wall that contacts the patient's lip superior and an upper, central, surface contacts the underside of the patient's nose. These two surfaces on the patient's face may form a nasolabial angle between them (seeFIG.2E). A cradle cushion may be shaped to have a nasolabial angle within the range of 90 degrees to 120 degrees.

Furthermore, the exemplary seal-forming structures3100may also be shaped and dimensioned such that no portion of the seal-forming structure3100enters into the patient's nares during use.

The exemplary seal-forming structures3100, while different in various aspects to be described further below, may each include at least two regions of different thickness: lateral support regions3108and a medial region3114. In further examples, there may also be a third region (in addition to the lateral support regions3108and the medial region3114) of another different thickness, a mid-lateral region3110. In still further examples, there may also be a fourth region (in addition to the lateral support regions3108, the mid-lateral regions3110, and the medial region3114) of another different thickness, an anterior region3109. As can be seen the depicted examples, the differing thicknesses may be produced by extending regions of different thickness different distances into the interior of the seal-forming structure3100such that the exterior surface of the seal-forming structure3100remains smooth. The exterior surface may not be uneven at transitional areas between the regions of different thickness. Thus, the exterior of the exemplary seal-forming structures3100is continuous and smooth.

5.3.1.7.1 Lateral Support Region

At each lateralmost side of each seal-forming structure3100the lateral support region3108may be provided. The exemplary seal-forming structures3100may include two lateral support regions3108, each spaced distal from a plane bisecting the seal-forming structure3100that would be parallel to the patient's sagittal plane in use. The lateral support regions3108may be the thickest portions of the seal-forming structure3100to provide resistance to lateral displacement, e.g., caused by the patient sleeping on the side of their head such that the pillow pushes laterally against the seal-forming structure, and to provide robust engagement against the patient's ala. The lateral support regions3108may have a thickness of approximately 0.9 mm to approximately 1.5 mm, or approximately 1.3 mm to approximately 1.4 mm, or approximately 1.3 mm, or approximately 1 mm to approximately 1.5 mm Due to the lateral support regions3108being the thickest regions of the seal-forming structure3100in the depicted examples and due to the exemplary seal-forming structures3100being constructed or molded from a single, homogeneous piece of material (e.g., liquid silicone rubber), the lateral support regions3108may also provide the greatest resistance to deformation.

Additionally, the lateral support regions3108may provide sufficient rigidity to ensure adequate sealing in the subalare region of the patient's face (i.e., the region where the ala terminate at the lip superior proximate the nasolabial sulcus), which is a region of particularly complex geometry. The subalare region of a patient's face presents particularly complex geometry because at least three facial surfaces—the ala, the lip superior, and the cheek—converge at this region. Thus, sufficient stiffness in the lateral support regions3108may ensure that the seal-forming structure3100can be urged into the subalare region by tension forces from the positioning and stabilising structure3300without collapsing. Insufficient rigidity at the portions of the seal-forming structure3100intended to engage this region of the patient's face, e.g., as a result of the material being too thin, could result in creasing, which forms leak paths from within the sealed region such that the pressurised gas can leak to atmosphere along paths formed within the creases between the exterior of the seal-forming structure3100and the patient's facial skin.

The lateral support regions3108may lie on the patient's face in a region inferior to the ala of the patient's nose as well as inferior and laterally outwards of the patient's nose, for example, between the nasolabial sulcus and the regions of the lip superior located inferior to the ala.

A dual wall design may be used to prevent collapse of the sealing surfaces, as disclosed inFIGS.7A-7Mof International Application Publication No. WO 2017/185140 A1, which is incorporated herein by reference in its entirety. The examples of the present technology include a seal-forming structure3100with a single wall and collapse of the sealing engagement is prevented by, e.g., the increased thickness of the seal-forming structure3100at the lateral support regions3108.

Furthermore, the lateral support regions3108may provide resistance to lateral displacement of the seal-forming structure3100when the patient's head moves. The seal-forming structure3100may be shaped and dimensioned such that when the example of the appropriate size is fitted to a given patient, the lateral support portions3108extend around and contact the patient's nasal alae. Since the facial structures underlying the skin of the alae are less rigid (e.g., cartilage and fibro fatty tissue as shown inFIG.2H), the alae may be more susceptible to deformation, but sufficient rigidity provided by the lateral support regions3108may ensure that the seal-forming structure3100maintains sealing engagement with the patient's alae when the patient's head moves (e.g., when tilting the head such that one side of the patient interface3000is forced against a pillow).

Depending on the shape and size of the patient's facial structures (e.g., nose, alae, lip superior, and cheeks), the lateral support regions3108may contact the patient's alae, lip superior, and/or cheeks in use. The lateral support regions3108, in some examples, may be shaped and dimensioned such that they avoid the patient's pronasale and/or subnasale.

FIGS.67-70depict examples of the seal-forming structures3100shown with exemplary naris outlines1001and nose base outlines1002. Although, these examples do not show the alar region of the nose base outline1002extending wide enough to contact the lateral support regions3108, it should be understood that the in use the lateral support regions3108may extend superiorly so as to envelop the alae. Therefore, the inferior portion of the patient's alae may not contact the lateral support portions3108, but the lateral portions of the patient's alae may contact the lateral support portions3108once the nose is received into the seal-forming structure3100. This fit is subject to the size and shape of the nose of a given patient and in some examples the patient's nose may be sufficiently wide so that the inferior portions of the alae do contact lateral support portions3108, in addition to the lateral portions of the alae. In further examples, the patient's nose may be so narrow that no portion of the alae contact the lateral support regions3108.

As can be seen inFIGS.67-70, there may be a rather abrupt transition (e.g., an abrupt taper or almost a step) between regions of different thickness. While facial geometry can vary widely between patients, the abrupt transitions may be located almost directly inferior to the nasal ala on the lip superior.

The edge of the lateral support regions3108may track upwardly, outwardly, and then inwardly to follow curvature of the nose in a superior direction starting from under patient's ala (e.g. “up” the patient's face on either side the nose following the curvature along either side of the nose). Thus, the lateral support regions3108support the seal-forming structure3100against the patient's face inferior to and on lateral sides of the patient's nose, while enabling the medial region3114to conform and seal to the alae and underside of the patient's nose.

The lateral support regions3108may extend from the plenum chamber3200all the way to the corners of the seal-forming structure3100to support and structurally rigidize the cushion. In some examples, the lateral support regions3108may be their thickest adjacent to where the seal-forming structure3100joins with the plenum chamber3200and then decreases in thickness away from the plenum chamber3200. The lateral support regions3108may not extend around the entirety of the plenum chamber3200, however. For example, the medial region3114, as described below, may extend to the peripheral edge of the plenum chamber3200at the central superior/anterior region of the seal-forming structure3100.

While the increased thickness of the lateral support regions3108may be desirable for structural rigidity, the seal-forming structure3100may still retain a degree of flexibility to enable the lateral portions of the seal-forming structure3100to be pushed laterally or pulled medially to accommodate noses of different widths. For example, the non-patient facing sides of the seal-forming structure3100(particularly the non-patient contacting regions on either lateral side of the seal-forming structure3100) may be thick enough to provide sufficient structural rigidity to the seal-forming structure3100, but may still be thin enough so that when the seal-forming structure3100is donned by a patient with a long narrow nose, the compressive forces in the anterior direction exerted by the patient's nose on the medial region3114are able to pull the lateral sides of the seal-forming structure3100(i.e., the lateral support portions3108) medially to bring the so that the seal-forming structure3100on either lateral side of the patient's nose contacts the patient's nose (e.g., at the alae). If a patient with a wider nose dons the seal-forming structure3100, the seal-forming structure3100may be sufficiently flexible such that there is not an excessive force in the medial direction on the lateral sides of the patient's nose, which may occur if the seal-forming structure3100is too stiff to tolerate a wider nose.

5.3.1.7.2 Medial Region

The medial region3114may be centrally located on the seal-forming structure3100. The medial region3114may be bisected by a plane that is parallel to the patient's sagittal plane in use. Since the medial region3114is centrally located, there may be only one such region.

In the depicted examples, naris openings3102may be formed through the medial region3102. The naris openings3102are positioned to generally align with patient's corresponding naris to provide the flow of pressurised gas to the patient's nares for inhalation and for exhaled gas to be passed back into the seal-forming structure3100for discharge to atmosphere via the plenum chamber vent3400, as described further below.FIGS.67-70show examples of the general alignment of the naris outlines1001with corresponding naris openings3102. These examples show that the naris outline1001may not necessarily match the size and shape of the naris opening1002because patients exhibit large variability in the size and shape of their nares.

As can be seen in the examples ofFIGS.67-70, the medial region3114may contact a substantial portion of the base or underside of the patient's nose. In many patients, this is a particularly sensitive region. Also, patients exhibit a large amount of variability in the geometry of the base or underside of the nose. Therefore, the medial region3114may be relatively thin as compared to other regions of the seal-forming structure3100to increase flexibility and conform to contours of the patient's facial and nasal geometry. In the depicted examples, the medial region3114is the thinnest region. In these examples, the medial region3114may have a thickness of approximately 0.25 mm.

The depicted examples show the mid-lateral regions3110laterally outward of the medial region3114, and the lateral support regions3108are shown further laterally outward. Thus, in some examples and depending on the size and shape of the patient's nose, the alae may not contact the medial region3114at all if the nose is wide enough. In patients with narrower noses, a portion of their alae may contact the medial region3114.

The medial region3114may also extend around to the anterior side of the seal-forming structure3100such that the patient's pronasale contacts a superior portion of the medial region3114. The patient's lip superior and/or subnasale may also contact an inferior portion of the medial region3114. The pronasale, lip superior, and subnasale may also be particularly sensitive regions and, therefore, it may be beneficial for the increased compliance of the medial region3114to engage these sensitive regions and reduce discomfort. As can be seen in the views of these examples,

Depending on the shape and size of the patient's facial structures (e.g., nose, alae, lip superior, and cheeks), the medial region3114may contact the patient's lip superior, subnasale, and/or pronasale in use. The medial region3114, in some examples, may be shaped and dimensioned such that they avoid the patient's pronasale and/or subnasale.

Within the medial region3114, there may be a pronasale region3117where the patient's pronasale may contact the seal-forming structure3100. However, it should be understood that shorter noses may not reach the pronasale region3117and longer noses may extend beyond the pronasale region3117such that the pronasale in either case does not contact the pronasale region3117. The pronasale region3117in the examples ofFIGS.16-28and67andFIGS.29-36and68may extend over to an anterior side of the seal-forming structure, i.e., away from the patient such that a portion of the pronasale region3117does not contact the patient's face. This arrangement may also allow the engagement of the pronsale to pull the lateral sides of the seal-forming structure3100medially to engage the alae. The pronasale region3117in the examples ofFIGS.37-44and69andFIGS.45-52and70may not extend so far forward as to have a portion that is not able to be contacted by the patient's nose because these shapes are intended for wider noses that may already be able to adequately engage lateral portions of the seal-forming structure3100.

Within the medial region3114, there may be a lip superior region3116where the patient's lip superior may contact the seal-forming structure3100. The patient's subnasale may also contact the seal-forming structure3100at the lip superior region3116. In some examples, the lip superior region3116may be adjacent to but not in direct contact with the patient's subnasale. Thus, there may be a gap between the patient's face and the seal-forming structure3100within the boundary of the seal formed against the patient's face.

Additionally, since the medial region3114is relatively thin, the pressure of the air within the seal-forming structure3100may cause the seal-forming structure3100to inflate during use. By inflating the seal-forming structure3100during use, the medial region3114is readily urged against the contours of the patient's face and nose, e.g., at the underside, at the alae, at lip superior, at the subnasale, and/or at the pronasale, to ensure an adequate seal.

While a relatively low material thickness may have benefits described above and below for the medial region3114, making the medial region3114too thin may result in excessive creasing, which in turn can form leak paths for gas to escape to atmosphere past the sealing boundary. Also, the medial region3114may benefit from being thick enough to maintain a stable seal that is not readily displace by movement of the patient or contact with objects such as pillows. Creasing may be of particular concern at the pronasale region3117, particularly along the centerline of the seal-forming structure3100(i.e., along a plane parallel to the patient's sagittal plane in use). Thus, in some examples the medial region3114may be thickened at the pronasale region3117relative to other portions of the medial region3114.

Within the medial region3114, there may also be a bridge portion3104positioned between the naris openings3102. The bridge portion3104may be long enough to be slack in an undeformed state such that when the patient's nose contacts the medial region3114the bridge portion3104can accommodate deformation of the seal-forming structure3100without stretching. The bridge portion3104may be thicker than the medial region3114or may be the same thickness. In an example, the bridge portion has a thickness of approximately 0.35 mm. An alternative way to resist tearing is for the bridge portion3104to be wider. Constructing the bridge portion3104with relatively greater thickness than the adjacent medial region3114may help to prevent tearing when the bridge portion3104is elongated by engagement of the seal-forming structure3100with the patient's nose. The bridge portion3104may be S-shaped to permit straightening to tolerate movement of the superior part of the medial region3114away from the inferior lip superior part. The bridge portion3104may be bowed, curved, and/or somewhat folded in its undeformed state.

The bridge portion3104may be longer or have more material than is necessary to bridge the gap between the top and bottom portions of the medial region3114. This extra material allows for extension while the bridge portion3104straightens, before becoming taut. If there was no extra material, the bridge portion3104could become taut upon a force applied to the top portion of the medial region3114, and the bridge portion3104would not tolerate any movement of the top portion of the medial region3114(and therefore may not achieve the effect of tolerating longer noses). Since the bridge portion3104may not necessarily engage and seal to the columella in order to fully seal around to the patient's nose, an adequate seal can be made to a small nose even if the bridge portion3104remains slack.

The bridge portion3104may maintain the integrity of the seal-forming structure3100in the medial region3114. If there were no bridge portion3104and instead a single air opening, due to the relatively thin wall thickness of the medial region3114, if the seal-forming structure3100is refitted (e.g., via pulling of the face and reseating) or receives aggressive dynamic loading whilst under pressure, there may be a risk that the pronasale region3117of the seal-forming structure3100would blow out (i.e., pressure from the gas would blow the sealing surface away from the nose and prevent sealing engagement). The bridge portion3104may prevent blow out by tying the pronasale region3117to the lip superior region3116.

Additionally, the bridge portion3104may prevent user set up error by preventing the patient's nose from being inserted into what would otherwise be a single hole.

5.3.1.7.3 Mid-Lateral Region

The mid-lateral regions3110may be provided laterally inward or in the medial direction relative to the lateral support regions3108. The mid-lateral regions3110may be laterally outward relative to the medial region3114. The exemplary seal-forming structures3100may include two mid-lateral regions3110, each spaced distal from a plane bisecting the seal-forming structure3100that would be parallel to the patient's sagittal plane in use. The mid-lateral regions3110may be positioned such that each mid-lateral region3110is adjacent to a corresponding lateral support region3108on one side and on the other side is adjacent to a corresponding side of the medial region3114.

Depending on the shape and size of the patient's facial structures (e.g., nose, alae, lip superior, and cheeks), the mid-lateral regions3110may contact the patient's alae in use. The mid-lateral regions3110, in some examples, may be shaped and dimensioned such that they avoid the patient's lip superior, cheeks, pronasale, and/or subnasale.FIGS.67-70show examples of the alae contacting the mid-lateral regions3110as the nose base outline1002extends to the mid-lateral regions3110at its widest point, which is the lateral boundary of the base of the alae. In other examples, where the patient has a relatively narrow nose, the nose base outline1002may remain within the boundary of the medial region3114such that the mid-lateral regions3110and the lateral support regions3108contact the lateral portions of the alae but not the underside. In other examples where the patient's nose is relatively wide, the base of the alae may extend beyond the mid-lateral regions3110to the lateral support regions3108.

The mid-lateral regions3110may be thicker than the medial region3110and thinner than the lateral support regions3108in some examples. The mid-lateral regions3110may have a thickness of approximately 0.5 mm to approximately 0.7 mm or approximately 0.6 mm or approximately 0.75 mm

5.3.1.7.4 Anterior Region

Further examples of the seal-forming structure3100may include an anterior region3109. The anterior region3109may face away from the patient in use and in some examples the patient's face may not contact the anterior region3109. The anterior region3109may be thinner than the lateral support regions3108and thicker than medial region3114in some examples. In some examples, the anterior region3109may have a thickness of approximately 0.5 mm to approximately 0.7 mm or approximately 0.6 mm or approximately 0.75 mm.

The anterior region3109may support the seal-forming structure3100by resisting compression of the seal-forming structure3100in the anterior direction during use.

5.3.1.7.5 Corner Region

The exemplary seal-forming structures3100may also include two corner regions3115formed at approximately the region where the medial region3114, the lateral support regions3108, and the mid-lateral regions3110converge. The corner regions3115may be located medially relative to the lateral support regions3108or relative to the lateral support regions3108and the mid-lateral regions3110.

As can be seen inFIGS.67-70, the corner regions3115may engage the patient's nose and face at approximately the region where the nose base outline1002terminates (i.e., at the subalare region). The corner regions3115may be shaped and dimensioned to extend into and seal with the subalare region of the patient's face. As explained above, the relatively thick lateral support regions3108may be effective at ensuring that an adequate seal is maintained at regions of relatively complex facial geometry, such as the subalare region. Thus, by extending the corner regions3115medially the lateral support regions3108or the lateral support regions3108and the mid-lateral regions3110extend into the subalare region to provide an effective seal in the complex and concave geometry of this region.

The alae in some patients may be significantly curved, and many patients may have very concave pockets or cavities where the ala meets the face, i.e., the subalare region. The pockets can result from alae that curve medially towards the sagittal plane between the widest part of the nose (i.e., along a line drawn from alar crest point to alar crest point across the sagittal plane) and the junction of the ala and the face (i.e., the subalare region). Providing thin material (i.e., the medial region3114component of the corner regions3115) to engage these corners of the patient's facial geometry may enable the seal-forming structure3100to deform to match the curvature of the ala and at least partially, if not completely, filling the concavities which may exist at the inferior corners of the patient's nose. The seal-forming structure3100may be configured so that the edge of the lateral support regions3108may be located on the patient's face laterally outward of the alae, but close enough to the alae so that the regions of the cushion contacting the patient's face on either inferior side of the nose are within the lateral support regions3108to support and stabilize to the seal-forming structure3100. The medial region3114component of the corner regions3115may deform to the extent that shelves are formed on which the patient's alae (at least the portions thereof proximate the lip superior) may lie in use, enabling the seal-forming structure3100to conform to the inferior periphery of the patient's nose in use, especially proximate the lip superior.

5.3.1.7.6 Crease Resistance

Providing the medial region3114to the seal-forming structure3100to seal to the underside of a patient's nose and providing the mid-lateral region3110and/or the lateral support portions3108around some or all of the medial region3114approximately at the periphery of the patient's nose may prevent propagation of creases formed on the relatively flexible and thin medial region3114.

As the medial region3114has a thin wall thickness and, therefore, may be relatively flexible, the medial region3114may be prone to creasing. The mid-lateral region3110may be thicker than the medial region3114and, therefore, may be less prone to creasing, particularly at the alar regions that may be more susceptible to creasing due to complex geometry. If a crease begins at a surface of the seal-forming structure3100that seals with the patient's skin and continues outside of the boundary of the seal, the crease may create a leak path through which gas can leak through the crease to ambient, past the patient's face. This may generate noise due to jetting and/or disruption due to the sensation of the gas flowing along the skin.

The mid-lateral regions3110, by virtue of the increased wall thickness, may resist creasing. If a crease occurs in the medial region3114, the mid-lateral region3110may be able to limit the size of the crease to prevent it from continuing up the sides of the seal-forming structure3100and past the surface forming a seal against the skin. Accordingly, the mid-lateral regions3110may act as a barrier to creases that closely follow the shape of the patient's nose, by being configured to lie at or proximate the edges of the patient's alae around the base of the nose.

Additionally, the mid-lateral regions3110may provide some medial preload to the lateral sides of the seal-forming structure3100. The patient's nose may act against this preload when the patient dons the mask, and in turn the lateral sides of the seal-forming structure3100are pushed into the alae to form a stable and robust seal. The preload may be designed to be large enough that the seal-forming structure3100can fit to and create a robust seal with a narrow nose, but not so large that it would be uncomfortable or resist sealing for a wider nose. Additionally, the preload on the sides of the nose may provide suspension between the nose and the rest of the seal-forming structure3100, providing a decoupling effect and allowing some lateral movement of the cushion in use without disrupting the seal.

5.3.1.7.7 Sealing and Comfort of the Seal-Forming Structure of the Present Technology Preferred by Patients

In an external clinical study, 19/23 patients rated the seal-forming structures3100of the present technology as having comfort above 7 on a scale of 1-10, 10 being the highest. In an external clinical study, 15/23 patients rated the seal-forming structures3100of the present technology as having comfort of a 9 or 10.

In a fitting study, the majority of patients (30/33) preferred the initial fit of the seal-forming structures3100of the present technology to that of a competitor product (Respironics DreamWear), praising its ease of fit, adjustment and seal. 30 of 33 patients (90%) found the seal-forming structures3100of the present technology very easy to fit and adjust.

31 out of 36 people rated the seal of the seal-forming structures3100of the present technology at a 9 or a 10 on a scale of 1-10, 10 being the highest. In this engineer-observed study, patients found that the seal of the seal-forming structures3100of the present technology was better at tolerating movement in a bed than the competitor product (Respironics DreamWear).

The majority of patients (31 out of 36 patients) who tested the seal-forming structures3100of the present technology loved them and would take them home as their mask of choice when compared with the competitor product (Respironics DreamWear).

The comfort preferences described in the preceding paragraphs may be associated with the comfort provided to the patient by the medial region3114, which provides compliant and conforming engagement with sensitive areas of the patient's face. The overall shape of the exemplary seal-forming structures3100may also contribute to the comfort.

The sealing preferences described in the preceding paragraphs may be associated with the medial region's3114ability to conform to the patient's nose to form an adequate seal. Also, the mid-lateral regions3110, the lateral support regions3108, and the corner regions3115may also contribute to the preference for the seal of the seal-forming structure3100of the present technology because of the way that these structures engage complex facial geometries to maintain an effective seal.

5.3.2 Plenum Chamber

The plenum chamber3200has a perimeter that is shaped to be complementary to the surface contour of the face of an average person in the region where a seal will form in use. In use, a marginal edge of the plenum chamber3200is positioned in close proximity to an adjacent surface of the face. Actual contact with the face is provided by the seal-forming structure3100. The seal-forming structure3100may extend in use about the entire perimeter of the plenum chamber3200. In some forms, the plenum chamber3200and the seal-forming structure3100are formed from a single homogeneous piece of material.

In certain forms of the present technology, the plenum chamber3200does not cover the eyes of the patient in use. In other words, the eyes are outside the pressurised volume defined by the plenum chamber. Such forms tend to be less obtrusive and/or more comfortable for the wearer, which can improve compliance with therapy.

In certain forms of the present technology, the plenum chamber3200is constructed from a transparent material, e.g. a transparent polycarbonate. The use of a transparent material can reduce the obtrusiveness of the patient interface, and help improve compliance with therapy. The use of a transparent material can aid a clinician to observe how the patient interface is located and functioning.

In certain forms of the present technology, the plenum chamber3200is constructed from a translucent material. The use of a translucent material can reduce the obtrusiveness of the patient interface, and help improve compliance with therapy.

FIGS.22-28,35,36,43,44,51, and52show examples of the seal-forming structure3100with the plenum chamber3200. The seal-forming structure3100, as described above, may be formed from a single, homogeneous piece of material (e.g., liquid silicone rubber), and may include a plenum chamber connection opening3106where the seal-forming structure3100is joined to the plenum chamber3200. The connection between the seal-forming structure3100and the plenum chamber3200at the plenum chamber connection opening3106may be a permanent bond. The connection between the seal-forming structure3100and the plenum chamber3200at the plenum chamber connection opening3106may be a chemical bond. The seal-forming structure3100may be joined to the plenum chamber3200at the plenum chamber connection opening3106without a mechanical interlock.

At each lateral side of the plenum chamber3200there may be a plenum chamber lateral end3202in the form of a hollow passageway. A plenum chamber connector3204may also be provided at each lateral side of the plenum chamber3200laterally outward of the plenum chamber lateral end3202. The plenum chamber connectors3204may connect to respective ends3314of the positioning and stabilising structure3300. The connection between the plenum chamber connectors3204and respective ends3314of the positioning and stabilising structure3300may be releasable at both sides. In other examples, one side may have a permanent connection while the other side has a releasable connection. In still further examples, both connections between the plenum chamber connectors3204and respective ends3314of the positioning and stabilising structure3300may be permanent.

The plenum chamber lateral ends3202may receive the flow of pressurised gas from the positioning and stabilising structure3300. The flow of pressurised gas may then pass through the plenum chamber3200, then through the seal-forming structure3100, and into the patient's airways for inhalation.

FIGS.55-61show examples of how the ends3114of the positioning and stabilising structure3300may be connected to the plenum chamber lateral ends3202. Each plenum chamber connector3204in these examples may include a notch3206that is connected to a clip projection3322of a clip3320with a snap-fit. Each plenum chamber connector3204may be split to allow deformation within the clip3320during connection. Each clip3320may be joined to a clip overmold3318, which is an intermediate component between the end3314of the positioning and stabilising structure3300. Surrounding the ends3314of the positioning and stabilising structure3300may be a lip3324that seals with the plenum chamber connector3204. The lip3324may surround the entire opening at the end3314of the positioning and stabilising structure3300to ensure a complete and gas tight seal against the plenum chamber connector end3204so that the entire flow of pressurised gas passing through the positioning and stabilising structure3330reaches the patient via the plenum chamber3200and the seal-forming structure3100.

The plenum chamber connectors3204may each include a chamfered edge3208and a slot3209. The chamfered edge3208may form a surface to engage the clip projections3322of the clip3320, e.g., as shown inFIG.57. The slots3209may allow the plenum chamber connectors3204to be deformed to a reduced cross-section when inserted into corresponding clips3320.

The clip overmold3318may be a thin layer of silicone material between the clip3320(e.g., constructed of polycarbonate) and the positioning and stabilising structure3300. The clip overmold3318may be constructed of silicone to improve bonding between the positioning and stabilising structure3300and the clip3320. Bonding between compression grade silicone (e.g., used for the positioning and stabilising structure3300) and plastic (such as the polycarbonate used for the clip332) may be poor. Thus, a layer of LSR (Liquid Silicone Rubber), in the form of the clip overmold3318, may be overmoulded between the clip3320and the compression grade silicone positioning and stabilising structure3300to improve bonding.

FIG.56also shows an alignment feature whereby two arrowheads, one on the plenum chamber3200and one on the positioning and stabilising structure3300, indicate proper engagement of the plenum chamber3200with the positioning and stabilising structure3300.

The plenum chamber connectors3204may be chamfered at their ends to provide lead-in angles for connection to the positioning and stabilising structure3300. These lead-in features may reduce the force needed to insert the plenum chamber connectors3204into the ends3314of the positioning and stabilising structure3300, specifically the clips3320. Additionally, the lead-in chamfers on the plenum chamber connectors3204may aid in self-alignment with the clips3320during assembly. The clips3320may also have lead-in chamfers to further assist in deforming the plenum chamber connectors3204for connection.

Notches3206may be provided to the plenum chamber connectors3204to for the clips3320to fit into during assembly for a snap-fit connection. Once the clip3320fits into the corresponding notch3206, the plenum chamber3200and the positioning and stabilising structure3300are removably joined together. These components can be disconnected by applying enough force for the clip projections3322to escape the corresponding notches3206. The edge of each of the notches3206distal relative to the end of the plenum chamber connector3204is provided with a surface at an angle with respect to the direction in which the plenum chamber3200pulled away from the clip3320during disassembly of the plenum chamber3200from the positioning and stabilising structure3300. The retention angle may provide optimum force for retaining the positioning and stabilising structure3300during use while allowing an easy disconnection of the plenum chamber3200and the positioning and stabilising structure3300. A steeper angle would make the connection more secure and avoid unintentional disassembly, but it would be more difficult for the patient to disassemble the system. The retention angle depicted strikes a balance resulting in secure assembly and ease of disassembly.

The plenum chamber connectors3204may be curved to match the curve of the inner profile of the positioning and stabilising structure3300. The upper one of the plenum chamber connectors3204inFIG.57is curved and does not flex during connection and disconnection. The lower one of the plenum chamber connectors3204inFIG.57is not curved and is able to flex during connection and disconnection in order to allow the plenum chamber connectors3204to fit into the clip3320inside the positioning and stabilising structure3300.

Providing a sufficient radius of curvature at the base of the split between the plenum chamber connectors3204may avoid stress concentrations. The rigid material (e.g., polycarbonate) could otherwise fail at this location due to the stress created when the bottom one of the plenum chamber connectors3204flexes to receive the clip3320.

The cross-sectional profile of the plenum chamber connectors3204may not follow the cross-section profile of the clip3320exactly. There may be more clearance at sides of the plenum chamber connectors3204than at the top and bottom, which may allow the clip3320to flex during assembly and disassembly without interfering with the plenum chamber connectors3204. When the plenum chamber connectors3204are pulled from the clip3320, the plenum chamber connectors3204may exert force on the clip3320in the up and down directions ofFIG.57, which may cause the sides of the clip3320to be drawn inwards as the clip deforms. Providing some clearance between the sides of the clip3320and the plenum chamber connectors3204may allow some room for the sides of the clip3320to move inwards without interfering with the plenum chamber connectors3204. The clip3320thickness may be chosen to allow both flexibility and the retention forces required to maintain a secure connection.

The end3314of the positioning and stabilising structure3300may be small enough to form an interference fit with the plenum chamber connectors3204to seal between the plenum chamber3200and the positioning and stabilising structure3300. The lip3324cross-section may be tapered to prevent rolling in of lip3324during assembly, which could adversely affect the seal.

FIGS.60and61show that the internal opening3201between the plenum chamber connectors3204and the interior of the plenum chamber3200may have a very similar geometry to the positioning and stabilising structure3300, avoiding changes that could adversely affect the flow dynamics and cause excessive pressure drop. The transition geometry from the inside of the plenum chamber connectors3204to the interior of the plenum chamber3200and the seal-forming structure3100may also minimize pressure drop and impedance.

5.3.2.1 Alternative Plenum Chamber Design

FIGS.64-66depict variations of the plenum chamber3200. In one example, the plenum chamber3200may be formed of a flexible material such as silicone rather than a rigid material such as polycarbonate. Thus, the plenum chamber3200may be more flexible and may better tolerate or decouple lateral forces on the positioning and stabilising structure3300, which may reduce the forces transmitted to the seal-forming structure3100that could disrupt the seal. A plenum chamber3200made from a more flexible material such as silicone may also be easier to remove from the tooling during manufacturing. In such an example, the connections to the gas-transporting positioning and stabilising structure3300may still be formed from a rigid material, e.g. polycarbonate.

In such an example, the seal-forming structure3100may be constructed of a very soft silicone, such as in the range of 30-40 Durometer. The plenum chamber3200may not be as soft (but still softer than a rigid material like polycarbonate), with a hardness in the range of 70-90 Durometer, for example. The plenum chamber connectors3204may formed from a hard, plastic material, such as polycarbonate or nylon. Vent holes3400, if the holes are large enough (or the silicone is stiff enough) could be provided as vent holes in the flexible material, e.g., silicone, of the plenum chamber3200. The holes in such examples should be sufficiently large or the material sufficiently to avoid occlusion. Alternatively, the plenum chamber3200could be provided with larger openings into which an inserts (e.g., a rigid material such as polycarbonate) having the vent holes could be fitted or overmoulded. This alternative is depicted inFIGS.62-63. A diffuser may also be provided with or in addition to the vent insert3242.

FIGS.64-66depict an example wherein the plenum chamber3200is split into two plenum chamber portions3260which are separated by a flexible material like silicone. Thus, the plenum chamber3200may flex at the center. This may provide some decoupling of forces between the positioning and stabilising structure3300and the seal-forming structure3100, and may also enable the seal-forming structure3100to deform and wrap around the patient's face. Each of the plenum chamber portions3260may be connected to the positioning and stabilising structure3300to direct gas into the plenum chamber3200. The plenum chamber portions3260may also include vents3400.

5.3.3 Positioning and Stabilising Structure

The seal-forming structure3100of the patient interface3000of the present technology may be held in sealing position in use by the positioning and stabilising structure3300.

In one form the positioning and stabilising structure3300provides a retention force at least sufficient to overcome the effect of the positive pressure in the plenum chamber3200to lift off the face.

In one form the positioning and stabilising structure3300provides a retention force to overcome the effect of the gravitational force on the patient interface3000.

In one form the positioning and stabilising structure3300provides a retention force as a safety margin to overcome the potential effect of disrupting forces on the patient interface3000, such as from tube drag, or accidental interference with the patient interface.

In one form of the present technology, a positioning and stabilising structure3300is provided that is configured in a manner consistent with being worn by a patient while sleeping. In one example the positioning and stabilising structure3300has a low profile, or cross-sectional thickness, to reduce the perceived or actual bulk of the apparatus. In one example, the positioning and stabilising structure3300comprises at least one strap having a rectangular cross-section. In one example the positioning and stabilising structure3300comprises at least one flat strap.

In one form of the present technology, a positioning and stabilising structure3300is provided that is configured so as not to be too large and bulky to prevent the patient from lying in a supine sleeping position with a back region of the patient's head on a pillow.

In one form of the present technology, a positioning and stabilising structure3300is provided that is configured so as not to be too large and bulky to prevent the patient from lying in a side sleeping position with a side region of the patient's head on a pillow.

In one form of the present technology, a positioning and stabilising structure3300is provided with a decoupling portion located between an anterior portion of the positioning and stabilising structure3300, and a posterior portion of the positioning and stabilising structure3300. The decoupling portion does not resist compression and may be, e.g. a flexible or floppy strap. The decoupling portion is constructed and arranged so that when the patient lies with their head on a pillow, the presence of the decoupling portion prevents a force on the posterior portion from being transmitted along the positioning and stabilising structure3300and disrupting the seal.

In one form of the present technology, a positioning and stabilising structure3300comprises a strap constructed from a laminate of a fabric patient-contacting layer, a foam inner layer and a fabric outer layer. In one form, the foam is porous to allow moisture, (e.g., sweat), to pass through the strap. In one form, the fabric outer layer comprises loop material to engage with a hook material portion.

In certain forms of the present technology, a positioning and stabilising structure3300comprises a strap that is extensible, e.g. resiliently extensible. For example the strap may be configured in use to be in tension, and to direct a force to draw a seal-forming structure into sealing contact with a portion of a patient's face. In an example the strap may be configured as a tie.

In one form of the present technology, the positioning and stabilising structure comprises a first tie, the first tie being constructed and arranged so that in use at least a portion of an inferior edge thereof passes superior to an otobasion superior of the patient's head and overlays a portion of a parietal bone without overlaying the occipital bone.

In one form of the present technology suitable for a nasal-only mask or for a full-face mask, the positioning and stabilising structure includes a second tie, the second tie being constructed and arranged so that in use at least a portion of a superior edge thereof passes inferior to an otobasion inferior of the patient's head and overlays or lies inferior to the occipital bone of the patient's head.

In one form of the present technology suitable for a nasal-only mask or for a full-face mask, the positioning and stabilising structure includes a third tie that is constructed and arranged to interconnect the first tie and the second tie to reduce a tendency of the first tie and the second tie to move apart from one another.

In certain forms of the present technology, a positioning and stabilising structure3300comprises a strap that is bendable and e.g. non-rigid. An advantage of this aspect is that the strap is more comfortable for a patient to lie upon while the patient is sleeping.

In certain forms of the present technology, a positioning and stabilising structure3300comprises a strap constructed to be breathable to allow moisture vapour to be transmitted through the strap,

In certain forms of the present technology, a system is provided comprising more than one positioning and stabilizing structure3300, each being configured to provide a retaining force to correspond to a different size and/or shape range. For example the system may comprise one form of positioning and stabilizing structure3300suitable for a large sized head, but not a small sized head, and another. suitable for a small sized head, but not a large sized head.

5.3.3.1 Positioning and Stabilising Structure of the Present Technology

FIGS.7-15depict examples of the present technology, including a positioning and stabilising structure3300. In these examples, the positioning and stabilising structure3300includes lateral portions3302and superior portions3304in the form of conduits or tubes that direct a flow pressurised gas from a hub3306to ends3314. The positioning and stabilising structure3300may be arranged such that the hub3306and the decoupling structure3500are positioned superior to the patient's head in use. As described below, the decoupling structure3500may be rotatable within the hub3306and when the patient is wearing the patient interface3000, e.g., during therapy, the location of the hub3306and the decoupling structure3500superior to the patient's head allows the patient to move more freely without becoming entangled with the air circuit4170.

The positioning and stabilising structure3300may be constructed of silicone. For example, the lateral portions3302, the superior portions3304, the hub3306, and the lateral ends3314may able constructed or molded from a single piece of silicone.

The superior portions3304of the positioning and stabilising structure3300have ridges and valleys (or concertina sections) that allow the superior portions3304to conform to the shape of the corresponding portion of the patient's head in use. The ridges and valleys of the superior portions3304allow the superior portions3304to be extended and contracted along the longitudinal axis to accommodate larger or smaller heads. The ridges and valleys of the superior portions3304allow the superior portions3304to be flexed to different radii of curvature to accommodate patient heads of different shapes and sizes.

The lateral portions3302portions of the positioning and stabilising structure3300may not be formed with the ridges and valleys of the superior portions3304. Therefore, the lateral portions3302may be less extensible and flexible than the superior portions3304, which may be advantageous because there is less variability in the shape and size of the lateral sides of a patient's head.

The ends3314may connect to respective plenum chamber lateral ends3202. As described above, the plenum chamber lateral ends3202receive the flow of pressurised gas from the positioning and stabilising structure3300, which passes through the plenum chamber3200, through the seal-forming structure3100, and on to the patient's airways. As described above, the ends3314may include clip overmolds3318and clips3320that facilitate connection of the ends3314to the plenum chamber connectors3204of a respective plenum chamber lateral end3202.

The lateral portions3302may also each include a tab3308that receives a posterior strap end portion3311of a posterior strap3310. The posterior strap3310may be length-adjustable, e.g., with a hook and loop material arrangement whereby one of the posterior strap end portion3311and the remainder of the posterior strap3310includes hook material on its exterior while the other includes loop material on its exterior. The length adjustability of the posterior strap3310allows tension on the lateral portions3302to be increased to pull the seal-forming structure3100into sealing engagement with the patient's face at a desired amount of pressure (i.e., sufficiently tight to avoid leaks while not so tight as to cause discomfort).

The lateral portions3302may also be provided with sleeves3312that cushion the patient's face against the lateral portions3302. The sleeves3312may be constructed of a breathable textile material that has a soft feel.

5.3.4 Vent

In one form, the patient interface3000includes a vent3400constructed and arranged to allow for the washout of exhaled gases, e.g. carbon dioxide.

In certain forms the vent3400is configured to allow a continuous vent flow from an interior of the plenum chamber3200to ambient whilst the pressure within the plenum chamber is positive with respect to ambient. The vent3400is configured such that the vent flow rate has a magnitude sufficient to reduce rebreathing of exhaled CO2by the patient while maintaining the therapeutic pressure in the plenum chamber in use.

One form of vent3400in accordance with the present technology comprises a plurality of holes, for example, about 20 to about 80 holes, or about 40 to about 60 holes, or about 45 to about 55 holes.

The vent3400may be located in the plenum chamber3200. The plenum chamber vent3400may comprise a plurality of holes, as described above. The holes of the plenum chamber vent3400may be divided into two groups spaced apart laterally. The axis of the flow path through each of the holes of the plenum chamber vent3400may be parallel such that cross-flow is avoided to prevent generation of additional noise. The vent holes may be circular.

FIG.54also shows that the holes of the plenum chamber vent3400may decrease in radius from the interior of the plenum chamber3200to the exterior. As shown, each vent hole is provided with a draft angle. Each hole has a smaller diameter at its anterior end than at its posterior end. The draft angle means that the holes do not have a small cross section across the entire chassis thickness, which helps to provide effective carbon dioxide wash out at high levels of humidification. Additionally, a larger draft angle may result in a plenum chamber3200that is easier to manufacture, especially when the plenum chamber3200is formed from an injection moulded plastics material. The draft angle enables relatively thick vent pins to be used in the mould and easier ejection.

The holes of the plenum chamber vent3400may be provided in two sets towards the middle of the plenum chamber3200and the sets may be symmetrical across the centreline of the plenum chamber3200. Providing a pattern of multiple vent holes may reduce noise and diffuse the flow concentration.

The holes of the plenum chamber vent3400may be placed at an optimum distance away from the centreline of the plenum chamber3200. Placing the holes of the plenum chamber vent3400towards the centreline may advantageously reduce the chance that the vent holes are blocked when the patient is sleeping on their side. However, placing the vent holes too close to the middle of the plenum chamber3200may result in excessive weakening of the plenum chamber3200at the centre, especially since the cross-section of the plenum chamber3200in the depicted examples is smallest at the centre due to the overall shape of the plenum chamber3200. The location of the holes of the plenum chamber vent3400may avoid hole blockage during side sleep while leaving the middle section of the chassis sufficiently strong.

The size of each vent hole and the number of vent holes may be optimised to achieve a balance between noise reduction while achieving the necessary carbon dioxide washout, even at extreme humidification. In the depicted examples, the vent holes of the plenum chamber vent3400may not provide the total amount of venting for the system. The decoupling structure3500may include a decoupling structure vent3402. The decoupling structure vent3402may include one hole or a plurality of holes through the decoupling structure3500. The decoupling structure vent3402may function to bleed off excess pressure generated by the RPT device4000before reaching the patient, while the plenum chamber vent3400may function to washout carbon dioxide exhaled by the patient during therapy.

FIGS.62and63show an alternative example of the plenum chamber vent3400in which holes are provided to a vent insert3242that attaches, removably or permanently, to the plenum chamber3200at a vent insert opening3240. The vent insert3242may be constructed from a material that is more flexible than the material of the plenum chamber3200.

5.3.5 Decoupling Structure(s)

In one form the patient interface3000includes at least one decoupling structure, for example, a swivel or a ball and socket.

The hub3306, described above, is connected to a decoupling structure3500, which is a rotatable elbow in these examples. The decoupling structure3500may be rotatable 360° within the hub3306in use. The decoupling structure3500may be removable from the hub3306by manually depressing buttons3504to release catches (not shown) from within the hub3306.

The decoupling structure3500may also include a swivel3502that allows for rotatable connection to an air circuit4170.

The rotatability of the decoupling structure3500, the decoupling structure3500being in the form of an elbow, and the rotatability of the swivel3502on the decoupling structure3500may all increased the degrees of freedom, which in turn reduce tube drag and torque on the patient interface3000caused by the connection to the air circuit4170.

5.3.6 Connection Port

Connection port3600allows for connection to the air circuit4170.

5.3.7 Forehead Support

In one form, the patient interface3000includes a forehead support3700.

5.3.8 Anti-Asphyxia Valve

In one form, the patient interface3000includes an anti-asphyxia valve.

5.3.9 Ports

In one form of the present technology, a patient interface3000includes one or more ports that allow access to the volume within the plenum chamber3200. In one form this allows a clinician to supply supplemental oxygen. In one form, this allows for the direct measurement of a property of gases within the plenum chamber3200, such as the pressure.

5.4 RPT DEVICE

An RPT device4000in accordance with one aspect of the present technology comprises mechanical, pneumatic, and/or electrical components and is configured to execute one or more algorithms4300, such as any of the methods, in whole or in part, described herein. The RPT device4000may be configured to generate a flow of air for delivery to a patient's airways, such as to treat one or more of the respiratory conditions described elsewhere in the present document.

In one form, the RPT device4000is constructed and arranged to be capable of delivering a flow of air in a range of −20 L/min to +150 L/min while maintaining a positive pressure of at least 6 cmH2O, or at least 10cmH2O, or at least 20 cmH2O.

The RPT device may have an external housing4010, formed in two parts, an upper portion4012and a lower portion4014. Furthermore, the external housing4010may include one or more panel(s)4015. The RPT device4000comprises a chassis4016that supports one or more internal components of the RPT device4000. The RPT device4000may include a handle4018.

The pneumatic path of the RPT device4000may comprise one or more air path items, e.g., an inlet air filter4112, an inlet muffler4122, a pressure generator4140capable of supplying air at positive pressure (e.g., a blower4142), an outlet muffler4124and one or more transducers4270, such as pressure sensors4272and flow rate sensors4274.

One or more of the air path items may be located within a removable unitary structure which will be referred to as a pneumatic block4020. The pneumatic block4020may be located within the external housing4010. In one form a pneumatic block4020is supported by, or formed as part of the chassis4016.

The RPT device4000may have an electrical power supply4210, one or more input devices4220, a central controller4230, a therapy device controller4240, a pressure generator4140, one or more protection circuits4250, memory4260, transducers4270, data communication interface4280and one or more output devices4290. Electrical components4200may be mounted on a single Printed Circuit Board Assembly (PCBA)4202. In an alternative form, the RPT device4000may include more than one PCBA4202.

5.4.1 RPT Device Mechanical & Pneumatic Components

An RPT device may comprise one or more of the following components in an integral unit. In an alternative form, one or more of the following components may be located as respective separate units.

5.4.1.1 Air Filter(s)

An RPT device in accordance with one form of the present technology may include an air filter4110, or a plurality of air filters4110.

In one form, an inlet air filter4112is located at the beginning of the pneumatic path upstream of a pressure generator4140.

In one form, an outlet air filter4114, for example an antibacterial filter, is located between an outlet of the pneumatic block4020and a patient interface3000.

5.4.1.2 Muffler(s)

An RPT device in accordance with one form of the present technology may include a muffler4120, or a plurality of mufflers4120.

In one form of the present technology, an inlet muffler4122is located in the pneumatic path upstream of a pressure generator4140.

In one form of the present technology, an outlet muffler4124is located in the pneumatic path between the pressure generator4140and a patient interface3000.

5.4.1.3 Pressure Generator

In one form of the present technology, a pressure generator4140for producing a flow, or a supply, of air at positive pressure is a controllable blower4142. For example the blower4142may include a brushless DC motor4144with one or more impellers. The impellers may be located in a volute. The blower may be capable of delivering a supply of air, for example at a rate of up to about 120 litres/minute, at a positive pressure in a range from about 4 cmH2O to about 20 cmH2O, or in other forms up to about 30 cmH2O. The blower may be as described in any one of the following patents or patent applications the contents of which are incorporated herein by reference in their entirety: U.S. Pat. Nos. 7,866,944; 8,638,014; 8,636,479; and PCT Patent Application Publication No. WO 2013/020167.

The pressure generator4140is under the control of the therapy device controller4240.

In other forms, a pressure generator4140may be a piston-driven pump, a pressure regulator connected to a high pressure source (e.g. compressed air reservoir), or a bellows.

5.4.1.4 Transducer(s)

Transducers may be internal of the RPT device, or external of the RPT device. External transducers may be located for example on or form part of the air circuit, e.g., the patient interface. External transducers may be in the form of non-contact sensors such as a Doppler radar movement sensor that transmit or transfer data to the RPT device.

In one form of the present technology, one or more transducers4270are located upstream and/or downstream of the pressure generator4140. The one or more transducers4270may be constructed and arranged to generate signals representing properties of the flow of air such as a flow rate, a pressure or a temperature at that point in the pneumatic path.

In one form of the present technology, one or more transducers4270may be located proximate to the patient interface3000.

In one form, a signal from a transducer4270may be filtered, such as by low-pass, high-pass or band-pass filtering.

5.4.1.4.1 Flow Rate Sensor

A flow rate sensor4274in accordance with the present technology may be based on a differential pressure transducer, for example, an SDP600 Series differential pressure transducer from SENSIRION.

In one form, a signal representing a flow rate from the flow rate sensor4274is received by the central controller4230.

5.4.1.4.2 Pressure Sensor

A pressure sensor4272in accordance with the present technology is located in fluid communication with the pneumatic path. An example of a suitable pressure sensor is a transducer from the HONEYWELL ASDX series. An alternative suitable pressure sensor is a transducer from the NPA Series from GENERAL ELECTRIC.

In one form, a signal from the pressure sensor4272is received by the central controller4230.

5.4.1.4.3 Motor Speed Transducer

In one form of the present technology a motor speed transducer4276is used to determine a rotational velocity of the motor4144and/or the blower4142. A motor speed signal from the motor speed transducer4276may be provided to the therapy device controller4240. The motor speed transducer4276may, for example, be a speed sensor, such as a Hall effect sensor.

5.4.1.5 Anti-Spill Back Valve

In one form of the present technology, an anti-spill back valve4160is located between the humidifier5000and the pneumatic block4020. The anti-spill back valve is constructed and arranged to reduce the risk that water will flow upstream from the humidifier5000, for example to the motor4144.

5.4.2 RPT Device Electrical Components

5.4.2.1 Power Supply

A power supply4210may be located internal or external of the external housing4010of the RPT device4000.

In one form of the present technology, power supply4210provides electrical power to the RPT device4000only. In another form of the present technology, power supply4210provides electrical power to both RPT device4000and humidifier5000.

5.4.2.2 Input Devices

In one form of the present technology, an RPT device4000includes one or more input devices4220in the form of buttons, switches or dials to allow a person to interact with the device. The buttons, switches or dials may be physical devices, or software devices accessible via a touch screen. The buttons, switches or dials may, in one form, be physically connected to the external housing4010, or may, in another form, be in wireless communication with a receiver that is in electrical connection to the central controller4230.

In one form, the input device4220may be constructed and arranged to allow a person to select a value and/or a menu option.

5.4.2.3 Central Controller

In one form of the present technology, the central controller4230is one or a plurality of processors suitable to control an RPT device4000.

Suitable processors may include an x86 INTEL processor, a processor based on ARM® Cortex®-M processor from ARM Holdings such as an STM32 series microcontroller from ST MICROELECTRONIC. In certain alternative forms of the present technology, a 32-bit RISC CPU, such as an STR9 series microcontroller from ST MICROELECTRONICS or a 16-bit RISC CPU such as a processor from the MSP430 family of microcontrollers, manufactured by TEXAS INSTRUMENTS may also be suitable.

In one form of the present technology, the central controller4230is a dedicated electronic circuit.

In one form, the central controller4230is an application-specific integrated circuit. In another form, the central controller4230comprises discrete electronic components.

The central controller4230may be configured to receive input signal(s) from one or more transducers4270, one or more input devices4220, and the humidifier5000.

The central controller4230may be configured to provide output signal(s) to one or more of an output device4290, a therapy device controller4240, a data communication interface4280, and the humidifier5000.

In some forms of the present technology, the central controller4230is configured to implement the one or more methodologies described herein, such as the one or more algorithms4300expressed as computer programs stored in a non-transitory computer readable storage medium, such as memory4260. In some forms of the present technology, the central controller4230may be integrated with an RPT device4000. However, in some forms of the present technology, some methodologies may be performed by a remotely located device. For example, the remotely located device may determine control settings for a ventilator or detect respiratory related events by analysis of stored data such as from any of the sensors described herein.

5.4.2.4 Clock

The RPT device4000may include a clock4232that is connected to the central controller4230.

5.4.2.5 Therapy Device Controller

In one form of the present technology, therapy device controller4240is a therapy control module4330that forms part of the algorithms4300executed by the central controller4230.

In one form of the present technology, therapy device controller4240is a dedicated motor control integrated circuit. For example, in one form a MC33035 brushless DC motor controller, manufactured by ONSEMI is used.

5.4.2.6 Protection Circuits

The one or more protection circuits4250in accordance with the present technology may comprise an electrical protection circuit, a temperature and/or pressure safety circuit.

5.4.2.7 Memory

In accordance with one form of the present technology the RPT device4000includes memory4260, e.g., non-volatile memory. In some forms, memory4260may include battery powered static RAM. In some forms, memory4260may include volatile RAM.

Memory4260may be located on the PCBA4202. Memory4260may be in the form of EEPROM, or NAND flash.

Additionally or alternatively, RPT device4000includes a removable form of memory4260, for example a memory card made in accordance with the Secure Digital (SD) standard.

In one form of the present technology, the memory4260acts as a non-transitory computer readable storage medium on which is stored computer program instructions expressing the one or more methodologies described herein, such as the one or more algorithms4300.

5.4.2.8 Data Communication Systems

In one form of the present technology, a data communication interface4280is provided, and is connected to the central controller4230. Data communication interface4280may be connectable to a remote external communication network4282and/or a local external communication network4284. The remote external communication network4282may be connectable to a remote external device4286. The local external communication network4284may be connectable to a local external device4288.

In one form, data communication interface4280is part of the central controller4230. In another form, data communication interface4280is separate from the central controller4230, and may comprise an integrated circuit or a processor.

In one form, remote external communication network4282is the Internet. The data communication interface4280may use wired communication (e.g. via Ethernet, or optical fibre) or a wireless protocol (e.g. CDMA, GSM, LTE) to connect to the Internet.

In one form, local external communication network4284utilises one or more communication standards, such as Bluetooth, or a consumer infrared protocol.

In one form, remote external device4286is one or more computers, for example a cluster of networked computers. In one form, remote external device4286may be virtual computers, rather than physical computers. In either case, such a remote external device4286may be accessible to an appropriately authorised person such as a clinician.

The local external device4288may be a personal computer, mobile phone, tablet or remote control.

5.4.2.9 Output Devices Including Optional Display, Alarms

An output device4290in accordance with the present technology may take the form of one or more of a visual, audio and haptic unit. A visual display may be a Liquid Crystal Display (LCD) or Light Emitting Diode (LED) display.

5.4.2.9.1 Display Driver

A display driver4292receives as an input the characters, symbols, or images intended for display on the display4294, and converts them to commands that cause the display4294to display those characters, symbols, or images.

5.4.2.9.2 Display

A display4294is configured to visually display characters, symbols, or images in response to commands received from the display driver4292. For example, the display4294may be an eight-segment display, in which case the display driver4292converts each character or symbol, such as the figure “0”, to eight logical signals indicating whether the eight respective segments are to be activated to display a particular character or symbol.

5.5 AIR CIRCUIT

An air circuit4170in accordance with an aspect of the present technology is a conduit or a tube constructed and arranged to allow, in use, a flow of air to travel between two components such as RPT device4000and the patient interface3000.

In particular, the air circuit4170may be in fluid connection with the outlet of the pneumatic block4020and the patient interface. The air circuit may be referred to as an air delivery tube. In some cases there may be separate limbs of the circuit for inhalation and exhalation. In other cases a single limb is used.

In some forms, the air circuit4170may comprise one or more heating elements configured to heat air in the air circuit, for example to maintain or raise the temperature of the air. The heating element may be in a form of a heated wire circuit, and may comprise one or more transducers, such as temperature sensors. In one form, the heated wire circuit may be helically wound around the axis of the air circuit4170. The heating element may be in communication with a controller such as a central controller4230. One example of an air circuit4170comprising a heated wire circuit is described in U.S. Pat. No. 8,733,349, which is incorporated herewithin in its entirety by reference.

5.5.1 Oxygen Delivery

In one form of the present technology, supplemental oxygen4180is delivered to one or more points in the pneumatic path, such as upstream of the pneumatic block4020, to the air circuit4170and/or to the patient interface3000.

5.6 HUMIDIFIER

5.6.1 Humidifier Overview

In one form of the present technology there is provided a humidifier5000(e.g. as shown inFIG.5A) to change the absolute humidity of air or gas for delivery to a patient relative to ambient air. Typically, the humidifier5000is used to increase the absolute humidity and increase the temperature of the flow of air (relative to ambient air) before delivery to the patient's airways.

The humidifier5000may comprise a humidifier reservoir5110, a humidifier inlet5002to receive a flow of air, and a humidifier outlet5004to deliver a humidified flow of air. In some forms, as shown inFIG.5AandFIG.5B, an inlet and an outlet of the humidifier reservoir5110may be the humidifier inlet5002and the humidifier outlet5004respectively. The humidifier5000may further comprise a humidifier base5006, which may be adapted to receive the humidifier reservoir5110and comprise a heating element5240.

5.6.2 Humidifier Components

5.6.2.1 Water Reservoir

According to one arrangement, the humidifier5000may comprise a water reservoir5110configured to hold, or retain, a volume of liquid (e.g. water) to be evaporated for humidification of the flow of air. The water reservoir5110may be configured to hold a predetermined maximum volume of water in order to provide adequate humidification for at least the duration of a respiratory therapy session, such as one evening of sleep. Typically, the reservoir5110is configured to hold several hundred millilitres of water, e.g. 300 millilitres (ml), 325 ml, 350 ml or 400 ml. In other forms, the humidifier5000may be configured to receive a supply of water from an external water source such as a building's water supply system.

According to one aspect, the water reservoir5110is configured to add humidity to a flow of air from the RPT device4000as the flow of air travels therethrough. In one form, the water reservoir5110may be configured to encourage the flow of air to travel in a tortuous path through the reservoir5110while in contact with the volume of water therein.

According to one form, the reservoir5110may be removable from the humidifier5000, for example in a lateral direction as shown inFIG.5AandFIG.5B.

The reservoir5110may also be configured to discourage egress of liquid therefrom, such as when the reservoir5110is displaced and/or rotated from its normal, working orientation, such as through any apertures and/or in between its sub-components. As the flow of air to be humidified by the humidifier5000is typically pressurised, the reservoir5110may also be configured to prevent losses in pneumatic pressure through leak and/or flow impedance.

5.6.2.2 Conductive Portion

According to one arrangement, the reservoir5110comprises a conductive portion5120configured to allow efficient transfer of heat from the heating element5240to the volume of liquid in the reservoir5110. In one form, the conductive portion5120may be arranged as a plate, although other shapes may also be suitable. All or a part of the conductive portion5120may be made of a thermally conductive material such as aluminium (e.g. approximately 2 mm thick, such as 1 mm, 1.5 mm, 2.5 mm or 3 mm), another heat conducting metal or some plastics. In some cases, suitable heat conductivity may be achieved with less conductive materials of suitable geometry.

5.6.2.3 Humidifier Reservoir Dock

In one form, the humidifier5000may comprise a humidifier reservoir dock5130(as shown inFIG.5B) configured to receive the humidifier reservoir5110. In some arrangements, the humidifier reservoir dock5130may comprise a locking feature such as a locking lever5135configured to retain the reservoir5110in the humidifier reservoir dock5130.

5.6.2.4 Water Level Indicator

The humidifier reservoir5110may comprise a water level indicator5150as shown inFIG.5A-5B. In some forms, the water level indicator5150may provide one or more indications to a user such as the patient1000or a care giver regarding a quantity of the volume of water in the humidifier reservoir5110. The one or more indications provided by the water level indicator5150may include an indication of a maximum, predetermined volume of water, any portions thereof, such as 25%, 50% or 75% or volumes such as 200 ml, 300 ml or 400 ml.

5.6.2.5 Humidifier Transducer(s)

The humidifier5000may comprise one or more humidifier transducers (sensors)5210instead of, or in addition to, transducers4270described above. Humidifier transducers5210may include one or more of an air pressure sensor5212, an air flow rate transducer5214, a temperature sensor5216, or a humidity sensor5218as shown inFIG.5C. A humidifier transducer5210may produce one or more output signals which may be communicated to a controller such as the central controller4230and/or the humidifier controller5250. In some forms, a humidifier transducer may be located externally to the humidifier5000(such as in the air circuit4170) while communicating the output signal to the controller.

5.6.2.5.1 Pressure Transducer

One or more pressure transducers5212may be provided to the humidifier5000in addition to, or instead of, a pressure sensor4272provided in the RPT device4000.

5.6.2.5.2 Flow Rate Transducer

One or more flow rate transducers5214may be provided to the humidifier5000in addition to, or instead of, a flow rate sensor4274provided in the RPT device4000.

5.6.2.5.3 Temperature Transducer

The humidifier5000may comprise one or more temperature transducers5216. The one or more temperature transducers5216may be configured to measure one or more temperatures such as of the heating element5240and/or of the flow of air downstream of the humidifier outlet5004. In some forms, the humidifier5000may further comprise a temperature sensor5216to detect the temperature of the ambient air.

5.6.2.5.4 Humidity Transducer

In one form, the humidifier5000may comprise one or more humidity sensors5218to detect a humidity of a gas, such as the ambient air. The humidity sensor5218may be placed towards the humidifier outlet5004in some forms to measure a humidity of the gas delivered from the humidifier5000. The humidity sensor may be an absolute humidity sensor or a relative humidity sensor.

5.6.2.6 Heating Element

A heating element5240may be provided to the humidifier5000in some cases to provide a heat input to one or more of the volume of water in the humidifier reservoir5110and/or to the flow of air. The heating element5240may comprise a heat generating component such as an electrically resistive heating track. One suitable example of a heating element5240is a layered heating element such as one described in the PCT Patent Application Publication No. WO 2012/171072, which is incorporated herewith by reference in its entirety.

In some forms, the heating element5240may be provided in the humidifier base5006where heat may be provided to the humidifier reservoir5110primarily by conduction as shown inFIG.5B.

5.6.2.7 Humidifier Controller

According to one arrangement of the present technology, a humidifier5000may comprise a humidifier controller5250as shown inFIG.5C. In one form, the humidifier controller5250may be a part of the central controller4230. In another form, the humidifier controller5250may be a separate controller, which may be in communication with the central controller4230.

In one form, the humidifier controller5250may receive as inputs measures of properties (such as temperature, humidity, pressure and/or flow rate), for example of the flow of air, the water in the reservoir5110and/or the humidifier5000. The humidifier controller5250may also be configured to execute or implement humidifier algorithms and/or deliver one or more output signals.

As shown inFIG.5C, the humidifier controller5250may comprise one or more controllers, such as a central humidifier controller5251, a heated air circuit controller5254configured to control the temperature of a heated air circuit4171and/or a heating element controller5252configured to control the temperature of a heating element5240.

5.7 BREATHING WAVEFORM

FIG.6shows a model typical breath waveform of a person while sleeping. The horizontal axis is time, and the vertical axis is respiratory flow rate. While the parameter values may vary, a typical breath may have the following approximate values: tidal volume Vt 0.5 L, inhalation time Ti 1.6 s, peak inspiratory flow rate Qpeak 0.4 L/s, exhalation time Te 2.4 s, peak expiratory flow rate Qpeak −0.5 L/s. The total duration of the breath, Ttot, is about 4 s. The person typically breathes at a rate of about 15 breaths per minute (BPM), with Ventilation Vent about 7.5 L/min. A typical duty cycle, the ratio of Ti to Ttot, is about 40%.

5.8 GLOSSARY

For the purposes of the present technology disclosure, in certain forms of the present technology, one or more of the following definitions may apply. In other forms of the present technology, alternative definitions may apply.

5.8.1 General

Air: In certain forms of the present technology, air may be taken to mean atmospheric air, and in other forms of the present technology air may be taken to mean some other combination of breathable gases, e.g. atmospheric air enriched with oxygen.

Ambient: In certain forms of the present technology, the term ambient will be taken to mean (i) external of the treatment system or patient, and (ii) immediately surrounding the treatment system or patient.

For example, ambient humidity with respect to a humidifier may be the humidity of air immediately surrounding the humidifier, e.g. the humidity in the room where a patient is sleeping. Such ambient humidity may be different to the humidity outside the room where a patient is sleeping.

In another example, ambient pressure may be the pressure immediately surrounding or external to the body.

In certain forms, ambient (e.g., acoustic) noise may be considered to be the background noise level in the room where a patient is located, other than for example, noise generated by an RPT device or emanating from a mask or patient interface. Ambient noise may be generated by sources outside the room.

Automatic Positive Airway Pressure (APAP) therapy: CPAP therapy in which the treatment pressure is automatically adjustable, e.g. from breath to breath, between minimum and maximum limits, depending on the presence or absence of indications of SDB events.

Continuous Positive Airway Pressure (CPAP) therapy: Respiratory pressure therapy in which the treatment pressure is approximately constant through a respiratory cycle of a patient. In some forms, the pressure at the entrance to the airways will be slightly higher during exhalation, and slightly lower during inhalation. In some forms, the pressure will vary between different respiratory cycles of the patient, for example, being increased in response to detection of indications of partial upper airway obstruction, and decreased in the absence of indications of partial upper airway obstruction.

Flow rate: The volume (or mass) of air delivered per unit time. Flow rate may refer to an instantaneous quantity. In some cases, a reference to flow rate will be a reference to a scalar quantity, namely a quantity having magnitude only. In other cases, a reference to flow rate will be a reference to a vector quantity, namely a quantity having both magnitude and direction. Flow rate may be given the symbol Q. ‘Flow rate’ is sometimes shortened to simply ‘flow’ or ‘airflow’.

In the example of patient respiration, a flow rate may be nominally positive for the inspiratory portion of a breathing cycle of a patient, and hence negative for the expiratory portion of the breathing cycle of a patient. Total flow rate, Qt, is the flow rate of air leaving the RPT device. Vent flow rate, Qv, is the flow rate of air leaving a vent to allow washout of exhaled gases. Leak flow rate, Ql, is the flow rate of leak from a patient interface system or elsewhere. Respiratory flow rate, Qr, is the flow rate of air that is received into the patient's respiratory system.

Humidifier: The word humidifier will be taken to mean a humidifying apparatus constructed and arranged, or configured with a physical structure to be capable of providing a therapeutically beneficial amount of water (H2O) vapour to a flow of air to ameliorate a medical respiratory condition of a patient.

Leak: The word leak will be taken to be an unintended flow of air. In one example, leak may occur as the result of an incomplete seal between a mask and a patient's face. In another example leak may occur in a swivel elbow to the ambient.

Noise, conducted (acoustic): Conducted noise in the present document refers to noise which is carried to the patient by the pneumatic path, such as the air circuit and the patient interface as well as the air therein. In one form, conducted noise may be quantified by measuring sound pressure levels at the end of an air circuit.

Noise, radiated (acoustic): Radiated noise in the present document refers to noise which is carried to the patient by the ambient air. In one form, radiated noise may be quantified by measuring sound power/pressure levels of the object in question according to ISO 3744.

Noise, vent (acoustic): Vent noise in the present document refers to noise which is generated by the flow of air through any vents such as vent holes of the patient interface.

Patient: A person, whether or not they are suffering from a respiratory condition.

Pressure: Force per unit area. Pressure may be expressed in a range of units, including cmH2O, g-f/cm2and hectopascal. 1 cmH2O is equal to 1 g-f/cm2and is approximately 0.98 hectopascal. In this specification, unless otherwise stated, pressure is given in units of cmH2O.

The pressure in the patient interface is given the symbol Pm, while the treatment pressure, which represents a target value to be achieved by the mask pressure Pm at the current instant of time, is given the symbol Pt.

Respiratory Pressure Therapy (RPT): The application of a supply of air to an entrance to the airways at a treatment pressure that is typically positive with respect to atmosphere.

Ventilator: A mechanical device that provides pressure support to a patient to perform some or all of the work of breathing.

5.8.1.1 Materials

Silicone or Silicone Elastomer: A synthetic rubber. In this specification, a reference to silicone is a reference to liquid silicone rubber (LSR) or a compression moulded silicone rubber (CMSR). One form of commercially available LSR is SILASTIC (included in the range of products sold under this trademark), manufactured by Dow Corning. Another manufacturer of LSR is Wacker. Unless otherwise specified to the contrary, an exemplary form of LSR has a Shore A (or Type A) indentation hardness in the range of about 35 to about 45 as measured using ASTM D2240.

Polycarbonate: a thermoplastic polymer of Bisphenol-A Carbonate.

5.8.1.2 Mechanical Properties

Resilience: Ability of a material to absorb energy when deformed elastically and to release the energy upon unloading.

Resilient: Will release substantially all of the energy when unloaded. Includes e.g. certain silicones, and thermoplastic elastomers.

Hardness: The ability of a material per se to resist deformation (e.g. described by a Young's Modulus, or an indentation hardness scale measured on a standardised sample size).‘Soft’ materials may include silicone or thermo-plastic elastomer (TPE), and may, e.g. readily deform under finger pressure.‘Hard’ materials may include polycarbonate, polypropylene, steel or aluminium, and may not e.g. readily deform under finger pressure.

Stiffness (or rigidity) of a structure or component: The ability of the structure or component to resist deformation in response to an applied load. The load may be a force or a moment, e.g. compression, tension, bending or torsion. The structure or component may offer different resistances in different directions.

Floppy structure or component: A structure or component that will change shape, e.g. bend, when caused to support its own weight, within a relatively short period of time such as 1 second.

Rigid structure or component: A structure or component that will not substantially change shape when subject to the loads typically encountered in use. An example of such a use may be setting up and maintaining a patient interface in sealing relationship with an entrance to a patient's airways, e.g. at a load of approximately 20 to 30 cmH2O pressure.

As an example, an I-beam may comprise a different bending stiffness (resistance to a bending load) in a first direction in comparison to a second, orthogonal direction. In another example, a structure or component may be floppy in a first direction and rigid in a second direction.

5.8.2 Respiratory Cycle

Apnea: According to some definitions, an apnea is said to have occurred when flow falls below a predetermined threshold for a duration, e.g. 10 seconds. An obstructive apnea will be said to have occurred when, despite patient effort, some obstruction of the airway does not allow air to flow. A central apnea will be said to have occurred when an apnea is detected that is due to a reduction in breathing effort, or the absence of breathing effort, despite the airway being patent. A mixed apnea occurs when a reduction or absence of breathing effort coincides with an obstructed airway.

Breathing rate: The rate of spontaneous respiration of a patient, usually measured in breaths per minute.

Duty cycle: The ratio of inhalation time, Ti to total breath time, Ttot.

Effort (breathing): The work done by a spontaneously breathing person attempting to breathe.

Expiratory portion of a breathing cycle: The period from the start of expiratory flow to the start of inspiratory flow.

Flow limitation: Flow limitation will be taken to be the state of affairs in a patient's respiration where an increase in effort by the patient does not give rise to a corresponding increase in flow. Where flow limitation occurs during an inspiratory portion of the breathing cycle it may be described as inspiratory flow limitation. Where flow limitation occurs during an expiratory portion of the breathing cycle it may be described as expiratory flow limitation.

Types of flow limited inspiratory waveforms:

(i) Flattened: Having a rise followed by a relatively flat portion, followed by a fall.

(ii) M-shaped: Having two local peaks, one at the leading edge, and one at the trailing edge, and a relatively flat portion between the two peaks.

(iii) Chair-shaped: Having a single local peak, the peak being at the leading edge, followed by a relatively flat portion.

(iv) Reverse-chair shaped: Having a relatively flat portion followed by single local peak, the peak being at the trailing edge.

Hypopnea: According to some definitions, a hypopnea is taken to be a reduction in flow, but not a cessation of flow. In one form, a hypopnea may be said to have occurred when there is a reduction in flow below a threshold rate for a duration. A central hypopnea will be said to have occurred when a hypopnea is detected that is due to a reduction in breathing effort. In one form in adults, either of the following may be regarded as being hypopneas:(i) a 30% reduction in patient breathing for at least 10 seconds plus an associated 4% desaturation; or(ii) a reduction in patient breathing (but less than 50%) for at least 10 seconds, with an associated desaturation of at least 3% or an arousal.

Hyperpnea: An increase in flow to a level higher than normal.

Inspiratory portion of a breathing cycle: The period from the start of inspiratory flow to the start of expiratory flow will be taken to be the inspiratory portion of a breathing cycle.

Patency (airway): The degree of the airway being open, or the extent to which the airway is open. A patent airway is open. Airway patency may be quantified, for example with a value of one (1) being patent, and a value of zero (0), being closed (obstructed).

Positive End-Expiratory Pressure (PEEP): The pressure above atmosphere in the lungs that exists at the end of expiration.

Peak flow rate (Qpeak): The maximum value of flow rate during the inspiratory portion of the respiratory flow waveform.

Respiratory flow rate, patient airflow rate, respiratory airflow rate (Qr): These terms may be understood to refer to the RPT device's estimate of respiratory flow rate, as opposed to “true respiratory flow rate” or “true respiratory flow rate”, which is the actual respiratory flow rate experienced by the patient, usually expressed in litres per minute.

Tidal volume (Vt): The volume of air inhaled or exhaled during normal breathing, when extra effort is not applied. In principle the inspiratory volume Vi (the volume of air inhaled) is equal to the expiratory volume Ve (the volume of air exhaled), and therefore a single tidal volume Vt may be defined as equal to either quantity. In practice the tidal volume Vt is estimated as some combination, e.g. the mean, of the inspiratory volume Vi and the expiratory volume Ve.

(inhalation) Time (Ti): The duration of the inspiratory portion of the respiratory flow rate waveform.

(exhalation) Time (Te): The duration of the expiratory portion of the respiratory flow rate waveform.

(total) Time (Ttot): The total duration between the start of one inspiratory portion of a respiratory flow rate waveform and the start of the following inspiratory portion of the respiratory flow rate waveform.

Typical recent ventilation: The value of ventilation around which recent values of ventilation Vent over some predetermined timescale tend to cluster, that is, a measure of the central tendency of the recent values of ventilation.

Upper airway obstruction (UAO): includes both partial and total upper airway obstruction. This may be associated with a state of flow limitation, in which the flow rate increases only slightly or may even decrease as the pressure difference across the upper airway increases (Starling resistor behaviour).

Ventilation (Vent): A measure of a rate of gas being exchanged by the patient's respiratory system. Measures of ventilation may include one or both of inspiratory and expiratory flow, per unit time. When expressed as a volume per minute, this quantity is often referred to as “minute ventilation”. Minute ventilation is sometimes given simply as a volume, understood to be the volume per minute.

5.8.3 Ventilation

Adaptive Servo-Ventilator (ASV): A servo-ventilator that has a changeable, rather than fixed target ventilation. The changeable target ventilation may be learned from some characteristic of the patient, for example, a respiratory characteristic of the patient.

Backup rate: A parameter of a ventilator that establishes the minimum breathing rate (typically in number of breaths per minute) that the ventilator will deliver to the patient, if not triggered by spontaneous respiratory effort.

Cycled: The termination of a ventilator's inspiratory phase. When a ventilator delivers a breath to a spontaneously breathing patient, at the end of the inspiratory portion of the breathing cycle, the ventilator is said to be cycled to stop delivering the breath.

Expiratory positive airway pressure (EPAP): a base pressure, to which a pressure varying within the breath is added to produce the desired mask pressure which the ventilator will attempt to achieve at a given time.

End expiratory pressure (EEP): Desired mask pressure which the ventilator will attempt to achieve at the end of the expiratory portion of the breath. If the pressure waveform template Π(Φ) is zero-valued at the end of expiration, i.e. Π(Φ)=0 when Φ=1, the EEP is equal to the EPAP.

Inspiratory positive airway pressure (IPAP): Maximum desired mask pressure which the ventilator will attempt to achieve during the inspiratory portion of the breath.

Pressure support: A number that is indicative of the increase in pressure during ventilator inspiration over that during ventilator expiration, and generally means the difference in pressure between the maximum value during inspiration and the base pressure (e.g., PS=IPAP−EPAP). In some contexts pressure support means the difference which the ventilator aims to achieve, rather than what it actually achieves.

Servo-ventilator: A ventilator that measures patient ventilation, has a target ventilation, and which adjusts the level of pressure support to bring the patient ventilation towards the target ventilation.

Spontaneous/Timed (S/T): A mode of a ventilator or other device that attempts to detect the initiation of a breath of a spontaneously breathing patient. If however, the device is unable to detect a breath within a predetermined period of time, the device will automatically initiate delivery of the breath.

Swing: Equivalent term to pressure support.

Triggered: When a ventilator delivers a breath of air to a spontaneously breathing patient, it is said to be triggered to do so at the initiation of the respiratory portion of the breathing cycle by the patient's efforts.

5.8.4 Anatomy

5.8.4.1 Anatomy of the Face

Ala: the external outer wall or “wing” of each nostril (plural: alar)

Alare: The most lateral point on the nasal ala.

Alar curvature (or alar crest) point: The most posterior point in the curved base line of each ala, found in the crease formed by the union of the ala with the cheek.

Auricle: The whole external visible part of the ear.

(nose) Bony framework: The bony framework of the nose comprises the nasal bones, the frontal process of the maxillae and the nasal part of the frontal bone.

(nose) Cartilaginous framework: The cartilaginous framework of the nose comprises the septal, lateral, major and minor cartilages.

Columella: the strip of skin that separates the nares and which runs from the pronasale to the upper lip.

Columella angle: The angle between the line drawn through the midpoint of the nostril aperture and a line drawn perpendicular to the Frankfort horizontal while intersecting subnasale.

Frankfort horizontal plane: A line extending from the most inferior point of the orbital margin to the left tragion. The tragion is the deepest point in the notch superior to the tragus of the auricle.

Glabella: Located on the soft tissue, the most prominent point in the midsagittal plane of the forehead.

Lateral nasal cartilage: A generally triangular plate of cartilage. Its superior margin is attached to the nasal bone and frontal process of the maxilla, and its inferior margin is connected to the greater alar cartilage.

Greater alar cartilage: A plate of cartilage lying below the lateral nasal cartilage. It is curved around the anterior part of the naris. Its posterior end is connected to the frontal process of the maxilla by a tough fibrous membrane containing three or four minor cartilages of the ala.

Nares (Nostrils): Approximately ellipsoidal apertures forming the entrance to the nasal cavity. The singular form of nares is naris (nostril). The nares are separated by the nasal septum.

Naso-labial sulcus or Naso-labial fold: The skin fold or groove that runs from each side of the nose to the corners of the mouth, separating the cheeks from the upper lip.

Naso-labial angle: The angle between the columella and the upper lip, while intersecting subnasale.

Otobasion inferior: The lowest point of attachment of the auricle to the skin of the face.

Otobasion superior: The highest point of attachment of the auricle to the skin of the face.

Pronasale: the most protruded point or tip of the nose, which can be identified in lateral view of the rest of the portion of the head.

Philtrum: the midline groove that runs from lower border of the nasal septum to the top of the lip in the upper lip region.

Pogonion: Located on the soft tissue, the most anterior midpoint of the chin.

Ridge (nasal): The nasal ridge is the midline prominence of the nose, extending from the Sellion to the Pronasale.

Sagittal plane: A vertical plane that passes from anterior (front) to posterior (rear). The midsagittal plane is a sagittal plane that divides the body into right and left halves.

Sellion: Located on the soft tissue, the most concave point overlying the area of the frontonasal suture.

Septal cartilage (nasal): The nasal septal cartilage forms part of the septum and divides the front part of the nasal cavity.

Subalare: The point at the lower margin of the alar base, where the alar base joins with the skin of the superior (upper) lip.

Subnasal point: Located on the soft tissue, the point at which the columella merges with the upper lip in the midsagittal plane.

Supramenton: The point of greatest concavity in the midline of the lower lip between labrale inferius and soft tissue pogonion

5.8.4.2 Anatomy of the Skull

Frontal bone: The frontal bone includes a large vertical portion, the squama frontalis, corresponding to the region known as the forehead.

Mandible: The mandible forms the lower jaw. The mental protuberance is the bony protuberance of the jaw that forms the chin.

Maxilla: The maxilla forms the upper jaw and is located above the mandible and below the orbits. The frontal process of the maxilla projects upwards by the side of the nose, and forms part of its lateral boundary.

Nasal bones: The nasal bones are two small oblong bones, varying in size and form in different individuals; they are placed side by side at the middle and upper part of the face, and form, by their junction, the “bridge” of the nose.

Nasion: The intersection of the frontal bone and the two nasal bones, a depressed area directly between the eyes and superior to the bridge of the nose.

Occipital bone: The occipital bone is situated at the back and lower part of the cranium. It includes an oval aperture, the foramen magnum, through which the cranial cavity communicates with the vertebral canal. The curved plate behind the foramen magnum is the squama occipitalis.

Orbit: The bony cavity in the skull to contain the eyeball.

Parietal bones: The parietal bones are the bones that, when joined together, form the roof and sides of the cranium.

Temporal bones: The temporal bones are situated on the bases and sides of the skull, and support that part of the face known as the temple.

Zygomatic bones: The face includes two zygomatic bones, located in the upper and lateral parts of the face and forming the prominence of the cheek.

5.8.4.3 Anatomy of the Respiratory System

Diaphragm: A sheet of muscle that extends across the bottom of the rib cage. The diaphragm separates the thoracic cavity, containing the heart, lungs and ribs, from the abdominal cavity. As the diaphragm contracts the volume of the thoracic cavity increases and air is drawn into the lungs.

Larynx: The larynx, or voice box houses the vocal folds and connects the inferior part of the pharynx (hypopharynx) with the trachea.

Lungs: The organs of respiration in humans. The conducting zone of the lungs contains the trachea, the bronchi, the bronchioles, and the terminal bronchioles. The respiratory zone contains the respiratory bronchioles, the alveolar ducts, and the alveoli.

Nasal cavity: The nasal cavity (or nasal fossa) is a large air filled space above and behind the nose in the middle of the face. The nasal cavity is divided in two by a vertical fin called the nasal septum. On the sides of the nasal cavity are three horizontal outgrowths called nasal conchae (singular “concha”) or turbinates. To the front of the nasal cavity is the nose, while the back blends, via the choanae, into the nasopharynx.

Pharynx: The part of the throat situated immediately inferior to (below) the nasal cavity, and superior to the oesophagus and larynx. The pharynx is conventionally divided into three sections: the nasopharynx (epipharynx) (the nasal part of the pharynx), the oropharynx (mesopharynx) (the oral part of the pharynx), and the laryngopharynx (hypopharynx).

5.8.5 Patient Interface

Anti-asphyxia valve (AAV): The component or sub-assembly of a mask system that, by opening to atmosphere in a failsafe manner, reduces the risk of excessive CO2rebreathing by a patient.

Elbow: An elbow is an example of a structure that directs an axis of flow of air travelling therethrough to change direction through an angle. In one form, the angle may be approximately 90 degrees. In another form, the angle may be more, or less than 90 degrees. The elbow may have an approximately circular cross-section. In another form the elbow may have an oval or a rectangular cross-section. In certain forms an elbow may be rotatable with respect to a mating component, e.g. about 360 degrees. In certain forms an elbow may be removable from a mating component, e.g. via a snap connection. In certain forms, an elbow may be assembled to a mating component via a one-time snap during manufacture, but not removable by a patient.

Frame: Frame will be taken to mean a mask structure that bears the load of tension between two or more points of connection with a headgear. A mask frame may be a non-airtight load bearing structure in the mask. However, some forms of mask frame may also be air-tight.

Headgear: Headgear will be taken to mean a form of positioning and stabilizing structure designed for use on a head. For example the headgear may comprise a collection of one or more struts, ties and stiffeners configured to locate and retain a patient interface in position on a patient's face for delivery of respiratory therapy. Some ties are formed of a soft, flexible, elastic material such as a laminated composite of foam and fabric.

Membrane: Membrane will be taken to mean a typically thin element that has, preferably, substantially no resistance to bending, but has resistance to being stretched.

Plenum chamber: a mask plenum chamber will be taken to mean a portion of a patient interface having walls at least partially enclosing a volume of space, the volume having air therein pressurised above atmospheric pressure in use. A shell may form part of the walls of a mask plenum chamber.

Seal: May be a noun form (“a seal”) which refers to a structure, or a verb form (“to seal”) which refers to the effect. Two elements may be constructed and/or arranged to ‘seal’ or to effect ‘sealing’ therebetween without requiring a separate ‘seal’ element per se.

Shell: A shell will be taken to mean a curved, relatively thin structure having bending, tensile and compressive stiffness. For example, a curved structural wall of a mask may be a shell. In some forms, a shell may be faceted. In some forms a shell may be airtight. In some forms a shell may not be airtight.

Stiffener: A stiffener will be taken to mean a structural component designed to increase the bending resistance of another component in at least one direction.

Strut: A strut will be taken to be a structural component designed to increase the compression resistance of another component in at least one direction.

Swivel (noun): A subassembly of components configured to rotate about a common axis, preferably independently, preferably under low torque. In one form, the swivel may be constructed to rotate through an angle of at least 360 degrees. In another form, the swivel may be constructed to rotate through an angle less than 360 degrees. When used in the context of an air delivery conduit, the sub-assembly of components preferably comprises a matched pair of cylindrical conduits. There may be little or no leak flow of air from the swivel in use.

Tie (noun): A structure designed to resist tension.

Vent: (noun): A structure that allows a flow of air from an interior of the mask, or conduit, to ambient air for clinically effective washout of exhaled gases. For example, a clinically effective washout may involve a flow rate of about 10 litres per minute to about 100 litres per minute, depending on the mask design and treatment pressure.

5.8.6 Shape of Structures

Products in accordance with the present technology may comprise one or more three-dimensional mechanical structures, for example a mask cushion or an impeller. The three-dimensional structures may be bounded by two-dimensional surfaces. These surfaces may be distinguished using a label to describe an associated surface orientation, location, function, or some other characteristic. For example a structure may comprise one or more of an anterior surface, a posterior surface, an interior surface and an exterior surface. In another example, a seal-forming structure may comprise a face-contacting (e.g. outer) surface, and a separate non-face-contacting (e.g. underside or inner) surface. In another example, a structure may comprise a first surface and a second surface.

To facilitate describing the shape of the three-dimensional structures and the surfaces, we first consider a cross-section through a surface of the structure at a point, p. SeeFIG.3BtoFIG.3F, which illustrate examples of cross-sections at point p on a surface, and the resulting plane curves.FIGS.3B to3Falso illustrate an outward normal vector at p. The outward normal vector at p points away from the surface. In some examples we describe the surface from the point of view of an imaginary small person standing upright on the surface.

5.8.6.1 Curvature in One Dimension

The curvature of a plane curve at p may be described as having a sign (e.g. positive, negative) and a magnitude (e.g. 1/radius of a circle that just touches the curve at p).

Positive curvature: If the curve at p turns towards the outward normal, the curvature at that point will be taken to be positive (if the imaginary small person leaves the point p they must walk uphill). SeeFIG.3B(relatively large positive curvature compared toFIG.3C) andFIG.3C(relatively small positive curvature compared toFIG.3B). Such curves are often referred to as concave.

Zero curvature: If the curve at p is a straight line, the curvature will be taken to be zero (if the imaginary small person leaves the point p, they can walk on a level, neither up nor down). SeeFIG.3D.

Negative curvature: If the curve at p turns away from the outward normal, the curvature in that direction at that point will be taken to be negative (if the imaginary small person leaves the point p they must walk downhill) SeeFIG.3E(relatively small negative curvature compared toFIG.3F) andFIG.3F(relatively large negative curvature compared toFIG.3E). Such curves are often referred to as convex.

5.8.6.2 Curvature of Two Dimensional Surfaces

A description of the shape at a given point on a two-dimensional surface in accordance with the present technology may include multiple normal cross-sections. The multiple cross-sections may cut the surface in a plane that includes the outward normal (a “normal plane”), and each cross-section may be taken in a different direction. Each cross-section results in a plane curve with a corresponding curvature. The different curvatures at that point may have the same sign, or a different sign. Each of the curvatures at that point has a magnitude, e.g. relatively small. The plane curves inFIGS.3B to3Fcould be examples of such multiple cross-sections at a particular point.

Principal curvatures and directions: The directions of the normal planes where the curvature of the curve takes its maximum and minimum values are called the principal directions. In the examples ofFIG.3BtoFIG.3F, the maximum curvature occurs inFIG.3B, and the minimum occurs inFIG.3F, henceFIG.3BandFIG.3Fare cross sections in the principal directions. The principal curvatures at p are the curvatures in the principal directions.

Region of a surface: A connected set of points on a surface. The set of points in a region may have similar characteristics, e.g. curvatures or signs.

Saddle region: A region where at each point, the principal curvatures have opposite signs, that is, one is positive, and the other is negative (depending on the direction to which the imaginary person turns, they may walk uphill or downhill).

Dome region: A region where at each point the principal curvatures have the same sign, e.g. both positive (a “concave dome”) or both negative (a “convex dome”).

Cylindrical region: A region where one principal curvature is zero (or, for example, zero within manufacturing tolerances) and the other principal curvature is non-zero.

Planar region: A region of a surface where both of the principal curvatures are zero (or, for example, zero within manufacturing tolerances).

Edge of a surface: A boundary or limit of a surface or region.

Path: In certain forms of the present technology, ‘path’ will be taken to mean a path in the mathematical—topological sense, e.g. a continuous space curve from f(0) to f(1) on a surface. In certain forms of the present technology, a ‘path’ may be described as a route or course, including e.g. a set of points on a surface. (The path for the imaginary person is where they walk on the surface, and is analogous to a garden path).

Path length: In certain forms of the present technology, ‘path length’ will be taken to mean the distance along the surface from f(0) to f(1), that is, the distance along the path on the surface. There may be more than one path between two points on a surface and such paths may have different path lengths. (The path length for the imaginary person would be the distance they have to walk on the surface along the path).

Straight-line distance: The straight-line distance is the distance between two points on a surface, but without regard to the surface. On planar regions, there would be a path on the surface having the same path length as the straight-line distance between two points on the surface. On non-planar surfaces, there may be no paths having the same path length as the straight-line distance between two points. (For the imaginary person, the straight-line distance would correspond to the distance ‘as the crow flies’.)

5.8.6.3 Space Curves

Space curves: Unlike a plane curve, a space curve does not necessarily lie in any particular plane. A space curve may be closed, that is, having no endpoints. A space curve may be considered to be a one-dimensional piece of three-dimensional space. An imaginary person walking on a strand of the DNA helix walks along a space curve. A typical human left ear comprises a helix, which is a left-hand helix, seeFIG.3Q. A typical human right ear comprises a helix, which is a right-hand helix, seeFIG.3R.FIG.3Sshows a right-hand helix. The edge of a structure, e.g. the edge of a membrane or impeller, may follow a space curve. In general, a space curve may be described by a curvature and a torsion at each point on the space curve. Torsion is a measure of how the curve turns out of a plane. Torsion has a sign and a magnitude. The torsion at a point on a space curve may be characterised with reference to the tangent, normal and binormal vectors at that point.

Tangent unit vector (or unit tangent vector): For each point on a curve, a vector at the point specifies a direction from that point, as well as a magnitude. A tangent unit vector is a unit vector pointing in the same direction as the curve at that point. If an imaginary person were flying along the curve and fell off her vehicle at a particular point, the direction of the tangent vector is the direction she would be travelling.

Unit normal vector: As the imaginary person moves along the curve, this tangent vector itself changes. The unit vector pointing in the same direction that the tangent vector is changing is called the unit principal normal vector. It is perpendicular to the tangent vector.

Binormal unit vector: The binormal unit vector is perpendicular to both the tangent vector and the principal normal vector. Its direction may be determined by a right-hand rule (see e.g.FIG.3P), or alternatively by a left-hand rule (FIG.3O).

Osculating plane: The plane containing the unit tangent vector and the unit principal normal vector. SeeFIGS.3O and3P.

Torsion of a space curve: The torsion at a point of a space curve is the magnitude of the rate of change of the binormal unit vector at that point. It measures how much the curve deviates from the osculating plane. A space curve which lies in a plane has zero torsion. A space curve which deviates a relatively small amount from the osculating plane will have a relatively small magnitude of torsion (e.g. a gently sloping helical path). A space curve which deviates a relatively large amount from the osculating plane will have a relatively large magnitude of torsion (e.g. a steeply sloping helical path). With reference toFIG.3S, since T2>T1, the magnitude of the torsion near the top coils of the helix ofFIG.3Sis greater than the magnitude of the torsion of the bottom coils of the helix ofFIG.3S

With reference to the right-hand rule ofFIG.3P, a space curve turning towards the direction of the right-hand binormal may be considered as having a right-hand positive torsion (e.g. a right-hand helix as shown inFIG.3S). A space curve turning away from the direction of the right-hand binormal may be considered as having a right-hand negative torsion (e.g. a left-hand helix).

Equivalently, and with reference to a left-hand rule (seeFIG.3O), a space curve turning towards the direction of the left-hand binormal may be considered as having a left-hand positive torsion (e.g. a left-hand helix). Hence left-hand positive is equivalent to right-hand negative. SeeFIG.3T.

5.8.6.4 Holes

A surface may have a one-dimensional hole, e.g. a hole bounded by a plane curve or by a space curve. Thin structures (e.g. a membrane) with a hole, may be described as having a one-dimensional hole. See for example the one dimensional hole in the surface of structure shown inFIG.3I, bounded by a plane curve.

A structure may have a two-dimensional hole, e.g. a hole bounded by a surface. For example, an inflatable tyre has a two dimensional hole bounded by the interior surface of the tyre. In another example, a bladder with a cavity for air or gel could have a two-dimensional hole. See for example the cushion ofFIG.3Land the example cross-sections therethrough inFIG.3MandFIG.3N, with the interior surface bounding a two dimensional hole indicated. In a yet another example, a conduit may comprise a one-dimension hole (e.g. at its entrance or at its exit), and a two-dimension hole bounded by the inside surface of the conduit. See also the two dimensional hole through the structure shown inFIG.3K, bounded by a surface as shown.

5.9 OTHER REMARKS

Unless the context clearly dictates otherwise and where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit, between the upper and lower limit of that range, and any other stated or intervening value in that stated range is encompassed within the technology. The upper and lower limits of these intervening ranges, which may be independently included in the intervening ranges, are also encompassed within the technology, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the technology.

Furthermore, where a value or values are stated herein as being implemented as part of the technology, it is understood that such values may be approximated, unless otherwise stated, and such values may be utilized to any suitable significant digit to the extent that a practical technical implementation may permit or require it.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this technology belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present technology, a limited number of the exemplary methods and materials are described herein.

When a particular material is identified as being used to construct a component, obvious alternative materials with similar properties may be used as a substitute. Furthermore, unless specified to the contrary, any and all components herein described are understood to be capable of being manufactured and, as such, may be manufactured together or separately.

It must be noted that as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include their plural equivalents, unless the context clearly dictates otherwise.

All publications mentioned herein are incorporated herein by reference in their entirety to disclose and describe the methods and/or materials which are the subject of those publications. The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present technology is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dates, which may need to be independently confirmed.

The terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced.

The subject headings used in the detailed description are included only for the ease of reference of the reader and should not be used to limit the subject matter found throughout the disclosure or the claims. The subject headings should not be used in construing the scope of the claims or the claim limitations.

Although the technology herein has been described with reference to particular examples, it is to be understood that these examples are merely illustrative of the principles and applications of the technology. In some instances, the terminology and symbols may imply specific details that are not required to practice the technology. For example, although the terms “first” and “second” may be used, unless otherwise specified, they are not intended to indicate any order but may be utilised to distinguish between distinct elements. Furthermore, although process steps in the methodologies may be described or illustrated in an order, such an ordering is not required. Those skilled in the art will recognize that such ordering may be modified and/or aspects thereof may be conducted concurrently or even synchronously.

It is therefore to be understood that numerous modifications may be made to the illustrative examples and that other arrangements may be devised without departing from the spirit and scope of the technology.

5.10 REFERENCE SIGNS LISTPatient1000naris outline1001nose base outline1002bed partner1100patient interface3000seal-forming structure3100naris opening3102bridge portion3104plenum chamber connection opening3106lateral support region3108anterior region3109mid-lateral region3110nose base region3112medial region3114corner region3115lip superior region3116pronasale region3117flexible region3150plenum chamber3200internal opening3201plenum chamber lateral end3202plenum chamber connector3204notch3206chamfered edge3208slot3209chord3210superior point3220inferior point3230vent insert opening3240vent insert3242plenum chamber portion3260positioning and stabilising structure3300lateral portion3302superior portion3304hub3306tab3308posterior strap3310posterior strap end portion3311sleeve3312end3314receiver3316clip overmold3318clip3320clip projection3322lip3324plenum chamber vent3400decoupling structure vent3402decoupling structure3500swivel connector3502button3504connection port3600forehead support3700RPT device4000external housing4010upper portion4012lower portion4014panel4015chassis4016handle4018pneumatic block4020air filter4110inlet air filter4112outlet air filter4114muffler4120inlet muffler4122outlet muffler4124pressure generator4140blower4142motor4144anti-spill back valve4160air circuit4170heated air circuit4171supplemental oxygen4180electrical components4200Printed Circuit Board Assembly (PCBA)4202power supply4210input device4220central controller4230clock4232therapy device controller4240protection circuits4250memory4260transducer4270pressure sensor4272flow rate sensor4274motor speed transducer4276data communication interface4280remote external communication network4282local external communication network4284remote external device4286local external device4288output device4290display driver4292display4294algorithms4300therapy control module4330humidifier5000humidifier inlet5002humidifier outlet5004humidifier base5006reservoir5110conductive portion5120humidifier reservoir dock5130locking lever5135water level indicator5150humidifier transducer5210pressure transducer5212flow rate transducer5214temperature transducer5216humidity sensor5218heating element5240humidifier controller5250central humidifier controller5251heating element controller5252air circuit controller5254