Patent Description:
The airways include a series of branching tubes, which become narrower, shorter and more numerous as they penetrate deeper into the lung. The prime function of the lung is gas exchange, allowing oxygen to move from the inhaled air into the venous blood and carbon dioxide to move in the opposite direction. The trachea divides into right and left main bronchi, which further divide eventually into terminal bronchioles. The bronchi make up the conducting airways, and do not take part in gas exchange. Further divisions of the airways lead to the respiratory bronchioles, and eventually to the alveoli. The alveolated region of the lung is where the gas exchange takes place, and is referred to as the respiratory zone. See "<NPL>.

Examples of respiratory disorders include Obstructive Sleep Apnea (OSA), Cheyne-Stokes Respiration (CSR), respiratory insufficiency, Obesity Hyperventilation Syndrome (OHS), Chronic Obstructive Pulmonary Disease (COPD), Neuromuscular Disease (NMD) and Chest wall disorders.

Various respiratory therapies, such as Continuous Positive Airway Pressure (CPAP) therapy, Non-invasive ventilation (NIV), Invasive ventilation (IV), and High Flow Therapy (HFT) have been used to treat one or more of the above respiratory disorders.

Respiratory pressure therapy is the application of a supply of air to an entrance to the airways at a controlled target pressure that is nominally positive with respect to atmosphere throughout the patient's breathing cycle (in contrast to negative pressure therapies such as the tank ventilator or cuirass).

Continuous Positive Airway Pressure (CPAP) therapy has been used to treat Obstructive Sleep Apnea (OSA). The mechanism of action is that continuous positive airway pressure acts as a pneumatic splint and may prevent upper airway occlusion, such as by pushing the soft palate and tongue forward and away from the posterior oropharyngeal wall. Treatment of OSA by CPAP therapy may be voluntary, and hence patients may elect not to comply with therapy if they find devices used to provide such therapy one or more of: uncomfortable, difficult to use, expensive and aesthetically unappealing.

Non-invasive ventilation (NIV) provides ventilatory support to a patient through the upper airways to assist the patient breathing and/or maintain adequate oxygen levels in the body by doing some or all of the work of breathing. The ventilatory support is provided via a non-invasive patient interface. NIV has been used to treat CSR and respiratory failure, in forms such as OHS, COPD, NMD and Chest Wall disorders. In some forms, the comfort and effectiveness of these therapies may be improved.

Invasive ventilation (IV) provides ventilatory support to patients that are no longer able to effectively breathe themselves and may be provided using a tracheostomy tube. In some forms, the comfort and effectiveness of these therapies may be improved.

These respiratory therapies may be provided by a respiratory therapy system or device. Such systems and devices may also be used to screen, diagnose, or monitor a condition without treating it.

A respiratory therapy system may comprise a Respiratory Pressure Therapy Device (RPT device), an air circuit, a humidifier, a patient interface, an oxygen source, and data management.

Another form of therapy system is a mandibular repositioning device.

A patient interface may be used to interface respiratory equipment to its wearer, for example by providing a flow of air to an entrance to the airways. The flow of air may be provided via a mask to the nose and/or mouth, a tube to the mouth or a tracheostomy tube to the trachea of a patient. Depending upon the therapy to be applied, the patient interface may form a seal, e.g., with a region of the patient's face, to facilitate the delivery of gas at a pressure at sufficient variance with ambient pressure to effect therapy, e.g., at a positive pressure of about <NUM> cmH<NUM>O relative to ambient pressure. For other forms of therapy, such as the delivery of oxygen, the patient interface may not include a seal sufficient to facilitate delivery to the airways of a supply of gas at a positive pressure of about <NUM> cmH<NUM>O. For flow therapies such as nasal HFT, the patient interface is configured to insufflate the nares but specifically to avoid a complete seal. One example of such a patient interface is a nasal cannula.

Certain other mask systems may be functionally unsuitable for the present field. For example, purely ornamental masks may be unable to maintain a suitable pressure. Mask systems used for underwater swimming or diving may be configured to guard against ingress of water from an external higher pressure, but not to maintain air internally at a higher pressure than ambient.

Certain masks may be clinically unfavourable for the present technology e.g. if they block airflow via the nose and only allow it via the mouth.

Certain masks may be uncomfortable or impractical for the present technology if they require a patient to insert a portion of a mask structure in their mouth to create and maintain a seal via their lips.

Certain masks may be impractical for use while sleeping, e.g. for sleeping while lying on one's side in bed with a head on a pillow.

CPAP therapy is highly effective to treat certain respiratory disorders, provided patients comply with therapy. If a mask is uncomfortable, or difficult to use a patient may not comply with therapy. Since it is often recommended that a patient regularly wash their mask, if a mask is difficult to clean (e.g., difficult to assemble or disassemble), patients may not clean their mask and this may impact on patient compliance.

While a mask for other applications (e.g. aviators) may not be suitable for use in treating sleep disordered breathing, a mask designed for use in treating sleep disordered breathing may be suitable for other applications.

For these reasons, patient interfaces for delivery of CPAP during sleep form a distinct field.

Patient interfaces may include a seal-forming structure. Since it is in direct contact with the patient's face, the shape and configuration of the seal-forming structure can have a direct impact the effectiveness and comfort of the patient interface.

A range of patient interface seal-forming structure technologies are disclosed in the following patent applications, assigned to <CIT>; <CIT>; <CIT>.

One form of nasal pillow is found in the Adam Circuit manufactured by Puritan Bennett. Another nasal pillow, or nasal puff is the subject of <CIT>.

ResMed Limited has manufactured the following products that incorporate nasal pillows: SWIFT™ nasal pillows mask, SWIFT™ II nasal pillows mask, SWIFT™ LT nasal pillows mask, SWIFT™ FX nasal pillows mask and MIRAGE LIBERTY™ full-face mask. The following patent applications, assigned to <CIT> (describing amongst other things aspects of the ResMed Limited SWIFT™ nasal pillows), <CIT> (describing amongst other things aspects of the ResMed Limited SWIFT™ LT nasal pillows); International Patent Applications <CIT> and <CIT> (describing amongst other things aspects of the ResMed Limited MIRAGE LIBERTY™ full-face mask); International Patent Application <CIT> (describing amongst other things aspects of the ResMed Limited SWIFT™ FX nasal pillows).

A seal-forming structure of a patient interface used for positive air pressure therapy is subject to the corresponding force of the air pressure to disrupt a seal. Thus a variety of techniques have been used to position the seal-forming structure, and to maintain it in sealing relation with the appropriate portion of the face.

One technique is the use of adhesives. See for example US Patent Application Publication No. <CIT>. However, the use of adhesives may be uncomfortable for some.

Another technique is the use of one or more straps and/or stabilising harnesses. Many such harnesses suffer from being one or more of ill-fitting, bulky, uncomfortable and awkward to use.

One form of a positioning and stabilising structure comprises a pair of gas delivery tubes to receive the flow of air from a connection port on top of the patient's head and to deliver the flow of air to the entrance of the patient's airways via the seal-forming structure. In examples the gas delivery tubes may be made from silicone.

It may be necessary to manufacture this form of positioning and stabilising structure in a number of different sizes in order to accommodate the full range of patient head sizes.

Some positioning and stabilising structures of the type described immediately above may be made from silicone. Since some patients may dislike the feel of the silicone against their skin, some positioning and stabilising structures of the prior art have been made with permanently attached textile sleeves covering at least part of the gas delivery tubes. However, such sleeves may make it difficult to inspect the conduit to confirm its cleanliness. It may also be difficult to properly clean the gas delivery tube with the sleeve in place.

A respiratory pressure therapy (RPT) device may be used individually or as part of a system to deliver one or more of a number of therapies described above, such as by operating the device to generate a flow of air for delivery to an interface to the airways. The flow of air may be pressure-controlled (for respiratory pressure therapies) or flow-controlled (for flow therapies such as HFT). Thus RPT devices may also act as flow therapy devices. Examples of RPT devices include a CPAP device and a ventilator.

An air circuit is a conduit or a tube constructed and arranged to allow, in use, a flow of air to travel between two components of a respiratory therapy system such as the RPT device and the patient interface. In some cases, there may be separate limbs of the air circuit for inhalation and exhalation. In other cases, a single limb air circuit is used for both inhalation and exhalation.

Delivery of a flow of air without humidification may cause drying of airways. The use of a humidifier with an RPT device and the patient interface produces humidified gas that minimizes drying of the nasal mucosa and increases patient airway comfort. In addition in cooler climates, warm air applied generally to the face area in and about the patient interface is more comfortable than cold air. Humidifiers therefore often have the capacity to heat the flow of air was well as humidifying it.

Some forms of treatment systems may include a vent to allow the washout of exhaled carbon dioxide. The vent may allow a flow of gas from an interior space of a patient interface, e.g., the plenum chamber, to an exterior of the patient interface, e.g., to ambient.

<CIT> discloses a headgear for noninvasive ventilation interface made up of a nasal cannula.

<CIT> discloses a system adapted to provide a flow of gas to an airway of a patient.

<CIT> discloses a device designed to comfortably and efficiently maintain medical tubing in place on the head of a hospitalized patient.

<CIT> discloses a device designed to eliminate the discomfort and irritation behind the ears caused from oxygen supply line tubes by having the oxygen supply line tube wrapped on the holster and off the ears and securely in place.

<CIT> discloses a patient interface that includes a sealing arrangement adapted to provide an effective seal with the patient's nose, an inlet conduit arrangement adapted to deliver breathable gas to the sealing arrangement, and a cover that substantially encloses the sealing arrangement and/or the inlet conduit arrangement.

<CIT> discloses a patient interface that comprises a support structure and a seal-forming structure.

<CIT> discloses an air delivery conduit that includes first and second conduit portions that cooperate to form the conduit, each conduit portion including an inner layer of a film laminate that forms an interior surface of the conduit and an outer layer of a textile that forms an exterior surface of the conduit.

<CIT> discloses a positioning and stabilising structure to hold a seal-forming structure in a therapeutically effective position on a head of a patient.

The present invention provides a patient contacting member as defined in claim <NUM>. Further preferred embodiments of the invention are defined in the dependent claims.

Reference will be made in the following description to various examples or aspects of the present technology. Examples or aspects disclosed herein which do not fall under the scope of the appended claims do not form part of the present invention, but are useful for understanding the principles of the invention.

The present technology is directed towards providing medical devices used in the screening, diagnosis, monitoring, amelioration, treatment, or prevention of respiratory disorders having one or more of improved comfort, cost, efficacy, ease of use and manufacturability.

A first aspect of the present technology relates to apparatus used in the screening, diagnosis, monitoring, amelioration, treatment or prevention of a respiratory disorder.

Another aspect of the present technology relates to methods used in the screening, diagnosis, monitoring, amelioration, treatment or prevention of a respiratory disorder.

An aspect of certain forms of the present technology is to provide methods and/or apparatus that improve the compliance of patients with respiratory therapy.

One form of the present technology comprises a patient contacting member comprising an elongate sleeve portion that is releasably engageable with a gas delivery tube which forms part of a positioning and stabilising structure for a patient interface.

Another form of the present technology comprises a system for positioning and stabilising a patient interface comprising a positioning and stabilising structure comprising at least one gas delivery tube, the system comprising a plurality of patient contacting members which are releasably engageable with the gas delivery tube.

One form of the present technology comprises a patient contacting member configured to releasably engage a gas delivery tube which forms part of a positioning and stabilising structure for a patient interface, the patient contacting member comprising an elongate sleeve portion which is engageable with the gas delivery tube and a strap configured to engage a back of a patient's head, in use.

Another aspect of certain forms of the present technology is a system for positioning and stabilising a patient interface comprising:.

Another aspect of certain forms of the present technology is a patient contacting member configured to releasably engage a gas delivery tube for a patient interface, wherein the patient contacting member comprises a patient contacting portion and a resiliently flexible clipping portion configured to releasably engage the gas delivery tube.

Another aspect of certain forms of the present technology is a patient contacting member configured to releasably engage a gas delivery tube structure for a patient interface, wherein the patient contacting member comprises a patient contacting portion and an engaging portion which defines a slot along a length thereof, wherein the slot is shaped and configured such that the gas delivery tube can be inserted into the patient contacting member through the slot.

Another aspect of certain forms of the present technology is a gas delivery tube assembly for a patient interface, the assembly comprising a gas delivery tube having a patient-facing side and a non patient-facing side, the assembly further comprising a liner member releasably connectable to the patient-facing side of the gas delivery tube, wherein one of the patient-facing side of the gas delivery tube and the liner member comprises at least one section of unbroken loop material and the other of the patient-facing side of the gas delivery tube and the liner member comprises at least one section of hook material configured to releasably engage the unbroken loop material.

An aspect of one form of the present technology is a method of manufacturing apparatus.

An aspect of certain forms of the present technology is a medical device that is easy to use, e.g. by a person who does not have medical training, by a person who has limited dexterity, vision or by a person with limited experience in using this type of medical device.

An aspect of one form of the present technology is a patient interface that may be washed in a home of a patient, e.g., in soapy water, without requiring specialised cleaning equipment. An aspect of one form of the present technology is a humidifier tank that may be washed in a home of a patient, e.g., in soapy water, without requiring specialised cleaning equipment.

The methods, systems, devices and apparatus described may be implemented so as to improve the functionality of a processor, such as a processor of a specific purpose computer, respiratory monitor and/or a respiratory therapy apparatus. Moreover, the described methods, systems, devices and apparatus can provide improvements in the technological field of automated management, monitoring and/or treatment of respiratory conditions, including, for example, sleep disordered breathing.

In one form, the present technology comprises a method for treating a respiratory disorder comprising applying positive pressure to the entrance of the airways of a patient <NUM>.

In one form, the present technology comprises a respiratory therapy system for treating a respiratory disorder. The respiratory therapy system may comprise an RPT device <NUM> for supplying a flow of air to the patient <NUM> via an air circuit <NUM> and a patient interface <NUM> or <NUM>.

A non-invasive patient interface <NUM> in accordance with one aspect of the present technology comprises the following functional aspects: a seal-forming structure <NUM>, a plenum chamber <NUM>, a positioning and stabilising structure <NUM>, a vent <NUM>, one form of connection port <NUM> for connection to air circuit <NUM>, and a forehead support <NUM>. 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 structure <NUM> is arranged to surround an entrance to the airways of the patient so as to maintain positive pressure at the entrance(s) to the airways of the patient <NUM>. The sealed patient interface <NUM> is therefore suitable for delivery of positive pressure therapy.

An unsealed patient interface <NUM>, in the form of a nasal cannula, includes nasal prongs 3810a, 3810b which can deliver air to respective nares of the patient <NUM> via respective orifices in their tips. Such nasal prongs do not generally form a seal with the inner or outer skin surface of the nares. The air to the nasal prongs may be delivered by one or more air supply lumens 3820a, 3820b that are coupled with the nasal cannula <NUM>. The lumens 3820a, 3820b lead from the nasal cannula <NUM> to a respiratory therapy device via an air circuit. The unsealed patient interface <NUM> is particularly suitable for delivery of flow therapies, in which the RPT device generates the flow of air at controlled flow rates rather than controlled pressures. The "vent" at the unsealed patient interface <NUM>, through which excess airflow escapes to ambient, is the passage between the end of the prongs 3810a and 3810b of the cannula <NUM> via the patient's nares to atmosphere.

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 interface <NUM> in 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 <NUM> cmH<NUM>O with respect to ambient.

In one form of the present technology, a seal-forming structure <NUM> provides a target seal-forming region, and may additionally provide a cushioning function. The target seal-forming region is a region on the seal-forming structure <NUM> where 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 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 chamber <NUM> acting 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 structure <NUM> comprises a sealing flange and a support flange. The sealing flange comprises a relatively thin member with a thickness of less than about <NUM>, for example about <NUM> to about <NUM>, which extends around the perimeter of the plenum chamber <NUM>. 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 chamber <NUM>, and extends at least part of the way around the perimeter. The support flange is or includes a springlike 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.

In one form the seal-forming structure of the non-invasive patient interface <NUM> comprises 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.

The seal-forming structure <NUM> of the patient interface <NUM> of the present technology may be held in sealing position in use by the positioning and stabilising structure <NUM>.

In one form the positioning and stabilising structure <NUM> provides a retention force at least sufficient to overcome the effect of the positive pressure in the plenum chamber <NUM> to lift off the face.

In one form the positioning and stabilising structure <NUM> provides a retention force to overcome the effect of the gravitational force on the patient interface <NUM>.

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

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

In one form of the present technology, a positioning and stabilising structure <NUM> is 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 structure <NUM> is 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 structure <NUM> is provided with a decoupling portion located between an anterior portion of the positioning and stabilising structure <NUM>, and a posterior portion of the positioning and stabilising structure <NUM>. 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 structure <NUM> and disrupting the seal.

In one form of the present technology, a positioning and stabilising structure <NUM> comprises 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 structure <NUM> comprises 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 certain forms of the present technology, a positioning and stabilising structure <NUM> comprises 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 system is provided comprising more than one positioning and stabilizing structure <NUM>, 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 structure <NUM> suitable 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.

In some forms of the present technology, the positioning and stabilising structure <NUM> comprises one or more tubes that deliver pressurised air received from a conduit forming part of the air circuit <NUM> from the RPT device to the patient's airways, for example through an interfacing structure <NUM> which comprises a plenum chamber <NUM> and seal-forming structure <NUM>, for example as shown in <FIG>. In examples, the positioning and stabilising structure <NUM> comprises two tubes <NUM> that deliver air to the seal-forming structure <NUM> from the air circuit <NUM>. The tubes <NUM> are an integral part of the positioning and stabilising structure <NUM> of patient interface <NUM> to position and stabilise the seal-forming structure <NUM> of the patient interface to the appropriate part of the patient's face (for example, the nose and/or mouth). This allows the conduit of air circuit <NUM> providing the flow of pressurised air to connect to a connection port <NUM> of the patient interface in a position other than in front of the patient's face which may be unsightly to some people. While the use of a pair of tubes <NUM> has some advantages (described below), in some examples the positioning and stabilising structure <NUM> comprises only a single tube <NUM> configured to overlie the patient's head on one side. A strap or other stabilising component may be provided to the other side of the patient's head between the top end of the single tube <NUM> and the seal-forming structure <NUM>, to provide balanced forces on the seal-forming structure <NUM>.

In certain forms of the present technology, the patient interface <NUM> may comprise a connection port <NUM> located proximal a top, side or rear portion of a patient's head. For example, in the form of the present technology illustrated in <FIG> the connection port <NUM> is located on top of the patient's head. In this example the patient interface <NUM> comprises an elbow <NUM> to which the connection port <NUM> is provided. The elbow <NUM> may swivel with respect to the positioning and stabilising structure <NUM> in order to decouple movement of a conduit connected to the connection port <NUM> from the positioning and stabilising structure <NUM>. The elbow <NUM> may connect to a fluid connection opening in the headgear tubing <NUM> or in a component to which the headgear tubing <NUM> is connected. Additionally, or alternatively, a conduit connected to the connection port <NUM> may swivel with respect to the elbow <NUM>. In the illustrated example, elbow <NUM> comprises a swivelling conduit connector comprising the connection port <NUM> to which a conduit of the air circuit <NUM> is able to connect, such that the conduit can rotate about its longitudinal axis with respect to the elbow <NUM>. In some examples the air circuit <NUM> may connect to the fluid connection opening. The elbow <NUM> may rotatably connect to the fluid connection opening or to a ring received in the fluid connection opening.

In the example shown in <FIG>, the two tubes <NUM> are integrally formed and comprise a fluid connection opening to which the swivel elbow connects. In other examples, where separate tubes are used, they may be indirectly connected together, for example each may be connected to a T-shaped conduit having two conduit arms each fluidly connectable to the tubes <NUM>. The crown connector may comprise a third conduit arm. The connection port <NUM> may comprise an elbow <NUM> received at the centre of the crown connector <NUM>. The elbow <NUM> may be configured to swivel.

In certain forms of the present technology, for example as shown in <FIG>, the positioning and stabilising structure <NUM> comprises at least one headgear strap <NUM> acting in addition to the tubes <NUM> to position and stabilise the seal-forming structure <NUM> in sealing position at the entrance to the patient's airways. In one example the patient interface <NUM> comprises a strap <NUM> forming part of the positioning and stabilising structure <NUM>. The strap <NUM> may be known as a back strap or a rear headgear strap, for example. In other examples of the present technology, one or more further straps may be provided. For example, a patient interface <NUM> according to an example of the present technology having a full face or oro-nasal cushion module may have a second, lower, strap configured to overlie the back of the patient's neck.

In certain examples of the present technology, the tubes <NUM> are configured to receive a strap <NUM> (for example by provision of tabs <NUM>) at the locations superior to and proximate the patient's ears. If the strap <NUM> connects to the tubes <NUM> too high with respect to the patient's head, the strap <NUM> may have a tendency to ride up the back of the patient's head. Additionally, the strap <NUM> could form too large an angle with respect to the superior portions of the headgear tubes <NUM>, resulting in the necessity for the patient to tighten the strap <NUM> excessively, which could result in excessive tension in the positioning and stabilising structure <NUM> and could make the strap <NUM> more likely to ride up the back of the patient's head. Accordingly, it is advantageous for the connection between the strap <NUM> and the tubes <NUM> to be provided as low as possible, but spaced from the top of the patient's ear sufficiently that upon tightening of the strap <NUM> the tubes <NUM> are not pulled into contact with the patient's ears.

As is described below, in other forms of the technology the tubes <NUM> are not configured to receive a strap <NUM>. In some forms of the technology the one or more straps may be connected to and/or may form part of a patient contacting member <NUM>, <NUM>. In these forms of the technology similar considerations to those discussed above apply in relation to the positioning of the strap(s).

Referring next to <FIG>, <FIG> and <FIG>, in some forms of the technology a patient contacting member <NUM> is provided. In the embodiments shown in <FIG> the patient contacting member <NUM> comprises an elongate sleeve portion <NUM> (or sleeve portion <NUM>) which is configured to releasably engage a tube <NUM> (e.g. conduit) of the positioning and stabilising structure <NUM>. In one form of the technology, the elongate sleeve portion <NUM> may be partially or completely formed from a textile. The textile may be woven or non-woven.

In examples the elongate sleeve portion <NUM> may be made from an elastic material, or may comprise one or more portions made from an elastic material, to facilitate insertion of the tube <NUM> through the elongate sleeve portion <NUM>. In examples the elongate sleeve portion <NUM> may be dimensioned to allow the tube <NUM> to slide through the elongate sleeve portion <NUM>, either with one or more elastic portions of the elongate sleeve portion <NUM> stretched out, or without stretching out any portion of the elongate sleeve portion <NUM>. The sleeve portion(s) <NUM> may be configured to allow repeated engagement and disengagement from the tube <NUM> (e.g. without damage) by a user (e.g. a patient), rather than being engaged and/or manufactured with the tube <NUM> by the manufacturer and being difficult or substantially impossible to disengage from the tube <NUM> (at least without damaging the patient contacting member and/or the tube) by the patient. <FIG> shows a sleeve <NUM> of the prior art which is of a type which is permanently engaged with the headgear tube <NUM> by the manufacturer.

In some forms of the technology the patient contacting member <NUM> further comprises a strap <NUM>, for example a back strap <NUM> as described above.

In some forms of the technology, the patient contacting member <NUM> comprises two sleeve portions <NUM>, each sleeve portion <NUM> configured to connect to a respective tube <NUM> provided on opposite sides of the positioning and stabilising structure <NUM>.

In the example shown in <FIG>, two sleeve portions <NUM> and a back strap <NUM> are integrally formed as a single piece, for example from the same material. However, in other forms of the technology (for example as shown in <FIG>) the back strap <NUM> may comprise two separate back strap portions <NUM> (only one of which is shown in <FIG>) which are connectable together by a suitable connector means <NUM>, for example an adjustable connector means <NUM> which allows the overall length of the back strap <NUM> to be adjusted. In examples, a hook and loop fastening system (for example Velcro ™) may be used. For example, the ends of the back strap portions <NUM> may be provided with a portion of unbroken loop material <NUM> and an adjacent portion of each back strap portion <NUM> may be provided with a portion of broken loop (e.g. hook) material <NUM>, such that each back strap portion <NUM> can be threaded through a suitable connector and can connect to itself. In other examples the positions of the broken loop material and unbroken loop material may be reversed on one or both of the back strap portions <NUM>. In other examples one of the back strap portions <NUM> may be provided with a portion of broken loop material and the other back strap portion <NUM> may be provided with a portion of unbroken loop material such that the two back strap portions <NUM> can be connected together without the use of an intermediate connector means. Additionally or alternatively, one or more portions of the back strap <NUM> may be formed from an elastically extensible material. In examples the back strap <NUM> may be stretched over the patient's head when donning or doffing the interface, without the patient otherwise needing to adjust the length of the back strap <NUM> or needing to disengage the back strap <NUM> from the patient contacting member <NUM>.

As shown in <FIG>, in one form of the technology the back strap <NUM> may be provided with a tag <NUM> which can be grasped by the patient to assist the patient in sliding the strap <NUM> over their head and into position when donning the interface.

In the example shown in <FIG>, the strap <NUM> is releasably connectable to a strap engaging portion of the sleeve portions <NUM>. In this example the ends of the sleeve portions <NUM> distal the interfacing structure <NUM> are provided with loops or slots <NUM> which can be engaged by the strap <NUM>. In the examples shown in <FIG>, <FIG> and <FIG>, each slot is provided in a tab <NUM>.

In one form of the technology one or both of the ends of the strap <NUM> are provided with a portion of hook material <NUM> which engages a portion of unbroken loop material <NUM> provided on an adjacent portion of the strap <NUM> to form an adjustable connection mechanism. In alternative forms of the technology the ends <NUM> of the strap <NUM> are provided with unbroken loop material <NUM> and a hook material <NUM> is provided to the exterior surface of the strap <NUM> for engaging the unbroken loop material <NUM>. Other forms of connector are also possible, for example buckles, magnetic connectors or other connectors.

As shown in <FIG>, in some forms of the technology each elongate sleeve portion <NUM> comprises a plurality of strap engaging portions, e.g. loops, eyes or slots <NUM>. In examples the elongate sleeve portion <NUM> may comprise a plurality of slots <NUM>, each of which can be selectively engaged by the strap <NUM>. This may allow the patient to choose the position of the strap <NUM> relative to the elongate sleeve portion <NUM> and/or the interfacing structure <NUM>. The loops, eyes or slots <NUM> may be provided in tabs <NUM> which may all be the same length, or may be two or more different lengths.

Selection of a particular strap engaging portion to connect the strap <NUM> to may affect the balance of forces within the headgear, and may thereby affect the fit of the interface, as is described herein. This may allow a range of users of different sizes to comfortably use the same form and/or size of positioning and stabilising structure <NUM>. Tabs <NUM> that extend further in the posterior direction may enable the back strap <NUM> to connect at a more posterior location, which may reduce the tendency of the strap <NUM> to ride up or down on the patient's head, resulting in a more stable positioning and stabilising structure <NUM> for some users.

In one form of the technology, shown in <FIG>, the patient contacting member <NUM> is provided with a further strap <NUM> in addition to the back strap <NUM> described above. In examples, the further strap <NUM> is provided near or at an end of the elongate sleeve portion <NUM> which is closest to, for example adjacent, the interfacing structure <NUM>, when in use (or is at least toward an inferior portion of the elongate sleeve portion). The further strap <NUM> may extend around the patient's neck in use. This example may be particularly suitable for use with full face masks, ultra compact oro-nasal masks and/or nasal masks. In some examples the further strap <NUM> may engage a slot in a tab <NUM> via a hook and loop fastening system, as described above. In other examples the further strap <NUM> may engage the tab <NUM> via an alternative connector, for example a magnetic connector, as shown in <FIG>.

In the examples shown in <FIG> and <FIG>, the elongate sleeve portion <NUM> may have a patient contacting side <NUM> which contacts at least the patient's cheek region in use.

Referring next to <FIG>, in examples the length L along the elongate sleeve portion <NUM> is greater than the width W of the elongate sleeve portion <NUM>. In some examples the length L (i.e. the length along the sleeve portion, e.g. the arc length), may be more than twice the width W of the elongate sleeve portion <NUM> (the width being measured parallel to the surface of the patient's face), for example more than four times the width W. In one embodiment the elongate sleeve portion <NUM> is dimensioned to cover substantially the entire portion of the patient contacting side <NUM> of the tube <NUM> between the interfacing structure <NUM> and the back strap <NUM>. In other forms of the technology the elongate sleeve portion <NUM> is dimensioned to cover the entire portion of the tube <NUM> between the interfacing structure <NUM> and the back strap <NUM> (excluding any window portions provided, as discussed below). In some forms of the technology the patient contacting side <NUM> of the elongate sleeve portion <NUM> contacts the patient's face from a point immediately adjacent the interfacing structure <NUM> to a point above the patient's ear.

Referring next to <FIG>, in some forms of the technology the non patient-contacting side of the patient contacting member <NUM> (or sleeve <NUM>) may comprise a window portion <NUM> which may be uncovered, covered by one or more fibres or cords which are sufficiently spaced apart to allow a user to see the tube <NUM> through the window portion <NUM>, and/or covered with a transparent material. This may allow the user to check that the tube <NUM> is clean (for example when the tube is itself transparent or translucent). Additionally or alternatively, the window portion <NUM> may be configured to increase the flexibility of the sleeve <NUM>, thereby making the sleeve <NUM> easier to engage with or disengage from the tube <NUM> without damage.

In the example shown in <FIG> the window portion <NUM> comprises an open mesh panel <NUM>. In one form of the technology the mesh panel <NUM> may be knitted to shape (e.g. integrally formed) with the sleeve.

In another form of the technology, shown in <FIG>, opposing sides of the window portion <NUM> may comprise spaced apart loops <NUM>. The loops 3375A provided to one side of the window portion <NUM> may be offset along the length of the window portion <NUM> relative to the loops 3375B on the opposite side of the window portion <NUM>. The opposing loops 3375A, 3375B may be interconnected by one or more suitable fibres or cords <NUM>.

In another form of the technology, shown in <FIG>, interlinked loops <NUM> of shock cord <NUM> may be provided to opposite sides of the window portion <NUM>. In the example shown the loops <NUM> are provided in interlinked pairs, with one loop in the pair opposite (e.g. directly opposite) the other loop of the pair. The shock cord <NUM> may be elastically extendible in length, meaning the circumference of the elongate sleeve portion <NUM> is elastically enlargeable in that region, in the sense that the circumference can be increased by exerting a suitable force, but is biased towards an original circumference by the interlinked shock cords <NUM>.

In other forms of the technology the window portion <NUM> may comprise a transparent material, for example a silicone panel.

In other forms of the technology, shown in <FIG> and <FIG>, a patient contacting member <NUM> comprises a body <NUM> configured to at least partially wrap around a tube <NUM> of a positioning and stabilising structure <NUM>, wherein the body <NUM> comprises a patient contacting side <NUM> and slot <NUM> on an opposite side of the body <NUM> to the patent contacting side.

The slot <NUM> may extend substantially longitudinally along the patient contacting member <NUM>, that is, along the entire length of the patient contacting member <NUM>. In some forms of the technology the slot <NUM> may be curved, for example, if the body <NUM> is curved, the sides <NUM> of the slot <NUM> may also be curved so as to be substantially parallel to the sides <NUM> of the body <NUM>. In other forms of the technology the sides <NUM> of the slot <NUM> may be non-parallel to each other and/or to the sides <NUM> of the body <NUM>.

In some forms of the technology the body <NUM>, or at least a portion of the body <NUM>, may be rigidised, that is, may have a greater resistance to bending than a tube <NUM> which it is intended to engage, in use. The slot <NUM> may be shaped and dimensioned such that the patient contacting member <NUM> can be engaged over a tube <NUM> of a positioning and stabilising structure <NUM> by inserting the tube <NUM> through the slot <NUM> (or considered another way, by snapping the body <NUM> over the tube). In some forms of the technology, portions of the body <NUM> adjacent the slot <NUM> and/or which form the edges of the slot <NUM> are resiliently flexible to form a clipping portion which makes engagement of the patient contacting member <NUM> over the tube <NUM> easier. In other forms of the technology the body <NUM> may be substantially rigid and the tube <NUM> may be sufficiently deformable to allow insertion through the slot <NUM>. In some forms of the technology the sides <NUM> of the slot <NUM> may be generally parallel to each other, but one or more portions may of the sides <NUM> may be closer together (e.g. to reduce the width of the slot <NUM>). These portions may ensure that the body <NUM> engages the tube <NUM> securely.

In examples the body <NUM> may be formed from a textile laminate. The laminate may comprise a textile and one or more of a silicone, foam or other plastic material, for example with the textile layer <NUM> provided as an outer layer of the laminate so as to be in contact with the patient's skin. In examples the body <NUM> may be thermoformed to provide rigidity to selected areas. In embodiments with integral straps <NUM>, for example as shown in <FIG>, the strap portion <NUM> may not be thermoformed, thereby maintaining its flexibility. Alternatively, a strap portion <NUM> may be formed from a separate piece of material. As shown in <FIG>, <FIG> and <FIG> to <NUM>, some embodiments of the patient contacting member <NUM> may not have a strap <NUM> or a strap engaging portion.

In some forms of the technology the opposed edges of the slot <NUM> may touch along some or all of their length, or one edge may overlap the other along some or all of its length, when the patient contacting member <NUM> has been engaged with a tube <NUM> of a positioning and stabilising structure <NUM>. For example, the portions of the body <NUM> adjacent the slot <NUM> and/or which form the edges of the slot <NUM> may be flexible enough to allow a user to move the edges of the slot apart to allow the tube <NUM> to be inserted into the patient contacting member <NUM>, and may then return to a configuration in which the edges are in contact, or in which one edge overlaps the other.

In another form of the technology the edges of the slot <NUM> may not contact each other or overlap, but an additional portion of more flexible material (for example a flap) may be provided to one or both edges <NUM> to cover the slot when the patient contacting member <NUM> is engaged with the tube <NUM>. The portion of material or flap may be connectable to the opposite edge of the slot (or to the material attached to the other side of the slot) by a suitable fastener, for example a hook and loop fastening system.

In the example shown in <FIG>, the patient contacting member <NUM> may comprise a body <NUM> formed from a textile layer <NUM> connected to a thermoplastic elastomer <NUM>, for example by overmoulding. The patient contacting side <NUM> of the body <NUM> may be provided with a plurality of protruding rib formations <NUM>.

The protruding rib formations <NUM> may provide regions between the rib formations in which there is no contact between the patient's skin and the patient contacting side <NUM> of the body <NUM>. These regions may allow the patient's skin to breath.

Patient contacting members <NUM> featuring such rib formations <NUM> may also be relatively flexible in the longitudinal direction, while maintaining a required stiffness in the transverse direction.

In other examples, patient contacting members <NUM> comprising a textile layer <NUM> connected to a thermoplastic elastomer <NUM> (e. g by overmoulding) may be formed without rib formations <NUM> and may have a substantially flat patient contacting side <NUM>.

In some forms of the technology a system for positioning and stabilising a patient interfacing portion may comprise a positioning and stabilising structure <NUM> comprising at least one gas delivery tube <NUM>, and a plurality of patient contacting members <NUM>, <NUM> as described above. Each of the patient contacting members <NUM>, <NUM> may be interchangeably engageable with the gas delivery tube <NUM>, that is, each patient contacting member can be engaged with the gas delivery tube <NUM> if the others have first been removed.

In one form of the technology at least one of the patient contacting members <NUM>, <NUM> may comprise a rigidised portion, or may be entirely rigidised, that is, it may have a greater resistance to bending in at least one plane (e.g. parallel to the surface of the patient's cheek) than the corresponding tube <NUM>.

One or more of the partially or entirely rigidised patient contacting members <NUM>, <NUM> may be curved along a portion of, or the entirety of, its longest dimension (i.e. length). As shown in <FIG>, the patient contact member <NUM>, <NUM> may have a chord length LC (e.g. straight line distance) and an arc length LA, where the arc length LA is the distance along the at least partially curved centreline CL of the patient contacting member. As seen in <FIG>, patient contacting members <NUM>, <NUM> having different curvatures may have different arc lengths LA<NUM>, LA<NUM>, but the same chord length LC. The less curved the patient contacting member is, the closer the arc length LA and the chord length LC will be.

Engaging such a rigidized patient contacting member <NUM>, <NUM> with a tube <NUM> of the positioning and stabilising structure <NUM> may result in the portion of the tube <NUM> which is in contact with patient contact member substantially adopting the curvature of the patient contacting member <NUM>, <NUM>. Therefore, in one form of the technology a positioning and stabilising structure <NUM> comprising a tube <NUM> may be adjusted to fit a particular patient by engaging a patient contacting member <NUM>, <NUM> having a suitable arc length LA and chord length LC. Because a plurality of patient contacting members <NUM>, <NUM> can have the same chord length but different arc lengths, and a plurality of patient contacting members <NUM>, <NUM> can have the same arc length but different chord lengths, a patient can select a patient contacting member <NUM>, <NUM> which both adjusts the fit of the positioning and stabilising structure <NUM> to the particular patient's head, and which locates a strap engaging portion and/or an integral back strap <NUM> in a suitable position on the patient's head. In this way a single size of positioning and stabilising structure <NUM> may be adapted for use by patients with a larger range of head shapes and sizes than similar positioning and stabilising structures of the prior art.

In one form of the technology a system for positioning and stabilising a patient interface portion may comprise a positioning and stabilising structure <NUM> comprising at least one gas delivery tube <NUM> and a plurality of patient contacting members <NUM>, <NUM> as described above, where a plurality of the patient contacting members <NUM>, <NUM> have the same chord length but different arc lengths. In another form of the technology a system for positioning and stabilising a patient interface may comprise a positioning and stabilising structure <NUM> comprising at least one gas delivery tube <NUM> and a plurality of patient contacting members <NUM>, <NUM> as described above, where a plurality of the patient contacting members have the same arc length but different chord lengths. In another form of the technology a system for positioning and stabilising a patient interface may comprise a positioning and stabilising structure <NUM> comprising at least one gas delivery tube <NUM> and a plurality of patient contacting members <NUM>, <NUM> as described above, where a first group of the patient contacting members has the same arc length but different chord lengths and a second group of the patient contacting members has the same chord length but different arc lengths, wherein the first and second groups each comprise a plurality of patient contacting members.

Referring next to <FIG>, in another form of the technology a gas delivery tube assembly <NUM> for use with a patient interface, for example a gas delivery tube assembly <NUM> which forms part of a positioning and stabilising structure <NUM> for the patient interface, comprises a gas delivery tube <NUM> which is releasably connectable to a liner member <NUM>.

The gas delivery tube <NUM> has a patient-facing side <NUM> and a non patient-facing side <NUM>. In some examples the patient-facing side <NUM> may contact the patient, although in examples some or all of the patient-facing side <NUM> of the gas delivery tube may not be in contact with the patient due to the presence of the liner member <NUM>.

At least one of the patient-facing side <NUM> of the gas delivery tube <NUM> and the liner member <NUM> may comprise at least one section of unbroken loop material, and the other of the patient facing side <NUM> of the gas delivery tube <NUM> and the liner member <NUM> comprises at least one section of hook or broken loop material configured to releasably engage the unbroken loop material. In the example shown in <FIG>, the gas delivery tube <NUM> is provided with a plurality of portions of broken loop material <NUM> spaced apart along the length of the tube <NUM>. The liner member <NUM> may comprise a plurality of portions of unbroken loop material, or may comprise a single portion of unbroken loop material along substantially an entire length of the liner member <NUM>.

The liner member <NUM> may comprise a laminate, for example comprising a textile outer (patient contacting) layer, and at least one cushioning layer, for example a layer of foam. In some forms of the technology the laminate may be sufficiently thick that portions of the patient facing side <NUM> of the gas delivery tube immediately adjacent the ends of the liner member <NUM> are held away from the patient's skin in use. In one form of the technology the liner is at least substantially <NUM> thick, for example <NUM>-<NUM>, for example <NUM>-<NUM>.

The section(s) of unbroken loop material and/or broken loop material provided to the gas delivery tube <NUM> may be moulded into the gas delivery tube <NUM> or may be connected by an adhesive or other suitable joining method.

In examples the gas delivery tube assembly <NUM> described above may be used in combination with a patient contacting member <NUM>, <NUM> as described above.

In one form, the patient interface <NUM> includes a vent <NUM> constructed and arranged to allow for the washout of exhaled gases, e.g. carbon dioxide.

In one form the patient interface <NUM> includes at least one decoupling structure, for example, a swivel or a ball and socket.

Connection port <NUM> allows for connection to the air circuit <NUM>.

In one form, the patient interface <NUM> includes a forehead support <NUM>.

In one form, the patient interface <NUM> includes an anti-asphyxia valve.

In one form of the present technology, a patient interface <NUM> includes one or more ports that allow access to the volume within the plenum chamber <NUM>. In one form this allows a clinician to supply supplementary oxygen. In one form, this allows for the direct measurement of a property of gases within the plenum chamber <NUM>, such as the pressure.

An RPT device <NUM> in accordance with one aspect of the present technology comprises mechanical, pneumatic, and/or electrical components and is configured to execute one or more algorithms <NUM>, such as any of the methods, in whole or in part, described herein. The RPT device <NUM> may 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 device <NUM> is constructed and arranged to be capable of delivering a flow of air in a range of -<NUM>/min to +<NUM>/min while maintaining a positive pressure of at least <NUM> cmH<NUM>O, or at least 10cmH<NUM>O, or at least <NUM> cmH<NUM>O.

In one form of the present technology there is provided a humidifier <NUM> (e.g. as shown in <FIG>) to change the absolute humidity of air or gas for delivery to a patient relative to ambient air. Typically, the humidifier <NUM> is 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 humidifier <NUM> may comprise a humidifier reservoir <NUM>, a humidifier inlet <NUM> to receive a flow of air, and a humidifier outlet <NUM> to deliver a humidified flow of air. In some forms, as shown in <FIG>, an inlet and an outlet of the humidifier reservoir <NUM> may be the humidifier inlet <NUM> and the humidifier outlet <NUM> respectively. The humidifier <NUM> may further comprise a humidifier base <NUM>, which may be adapted to receive the humidifier reservoir <NUM> and comprise a heating element <NUM>.

Various respiratory therapy modes may be implemented by the disclosed respiratory therapy system.

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'.

Flow therapy: Respiratory therapy comprising the delivery of a flow of air to an entrance to the airways at a controlled flow rate referred to as the treatment flow rate that is typically positive throughout the patient's breathing cycle.

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 (H<NUM>O) vapour to a flow of air to ameliorate a medical respiratory condition of a patient.

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 cmH<NUM>O, g-f/cm<NUM> and hectopascal. <NUM> cmH<NUM>O is equal to <NUM>-f/cm<NUM> and is approximately <NUM> hectopascal (<NUM> hectopascal = <NUM> Pa = <NUM> N/m<NUM> = <NUM> millibar ~ <NUM> atm). In this specification, unless otherwise stated, pressure is given in units of cmH<NUM>O.

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 interface 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.

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 <NUM> to about <NUM> as measured using ASTM D2240.

Polycarbonate: a thermoplastic polymer of Bisphenol-A Carbonate.

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).

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. The inverse of stiffness is flexibility.

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 <NUM> 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 <NUM> to <NUM> cmH<NUM>O 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.

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.

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.

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).

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 CO<NUM> rebreathing 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 <NUM> degrees. In another form, the angle may be more, or less than <NUM> 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 <NUM> 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 <NUM> degrees. In another form, the swivel may be constructed to rotate through an angle less than <NUM> 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 <NUM> litres per minute to about <NUM> litres per minute, depending on the mask design and treatment pressure.

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. See <FIG>, which illustrate examples of cross-sections at point p on a surface, and the resulting plane curves. <FIG> also 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.

The curvature of a plane curve at p may be described as having a sign (e.g. positive, negative) and a magnitude (e.g. <NUM>/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). See <FIG> (relatively large positive curvature compared to <FIG> (relatively small positive curvature compared to <FIG>). 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).

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). See <FIG> (relatively small negative curvature compared to <FIG> (relatively large negative curvature compared to <FIG>). Such curves are often referred to as convex.

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 in <FIG> could 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 of <FIG>, the maximum curvature occurs in <FIG>, and the minimum occurs in <FIG>, hence <FIG> are 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(<NUM>) to f(<NUM>) 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(<NUM>) to f(<NUM>), 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'.

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, see <FIG>. A typical human right ear comprises a helix, which is a right-hand helix, see <FIG> shows 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>), or alternatively by a left-hand rule (<FIG>).

Osculating plane: The plane containing the unit tangent vector and the unit principal normal vector.

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 to <FIG>, since T2>T1, the magnitude of the torsion near the top coils of the helix of <FIG> is greater than the magnitude of the torsion of the bottom coils of the helix of <FIG>.

With reference to the right-hand rule of <FIG>, 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 in <FIG>). 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 (see <FIG>), 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.

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 in <FIG>, 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 of <FIG> and the example cross-sections therethrough in <FIG>, 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 in <FIG>, bounded by a surface as shown.

All publications mentioned 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.

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 scope of the technology.

Claim 1:
A patient contacting member (<NUM>) configured to releasably engage a gas delivery tube (<NUM>) which forms part of a positioning and stabilising structure (<NUM>) for a patient interface (<NUM>), the patient contacting member (<NUM>) comprising an elongate sleeve portion (<NUM>) which is engageable with the gas delivery tube (<NUM>) and a strap (<NUM>) configured to engage a back of a patient's head, in use,
the elongate sleeve portion (<NUM>) comprising a patient contacting side (<NUM>) and a non-patient contacting side, wherein the patient contacting side (<NUM>) contacts at least the patient's cheek region, in use,
characterised in that the non-patient contacting side comprises a window portion (<NUM>),
wherein the window portion (<NUM>) comprises a cover which allows the patient to see through the window portion (<NUM>).