Headgear strap for a patient interface

Abstract

A strap for a positioning and stabilising structure for a patient interface configured to deliver breathable gas at a therapeutic pressure to an entrance of a patient's airways. The strap may comprise a patient-facing layer, a non-patient-facing layer and a middle layer positioned between them. The strap may further comprise first and second bonding layers that bond the other layers together. The bonding layers may be formed from a thermoplastic or thermoset, for example a thermoplastic elastomer film. The strap may be formed by thermoforming. The strap may comprise a central region that is thicker than edge regions. A strap may comprise an edge layer. In some forms, a strap may comprise an inner layer and an outer layer with a void between lateral edges of the inner layer and the outer layer.

Description

HEADGEAR STRAP FOR A PATIENT INTERFACE1 BACKGROUND OF THE TECHNOLOGY1.1 FIELD OF THE TECHNOLOGY

[0001] The present technology relates to one or more of the screening, diagnosis, monitoring, treatment, prevention and amelioration of respiratory-related disorders. The present technology also relates to medical devices or apparatus, and their use.1.2 DESCRIPTION OF THE RELATED ART1.2.1 Human Respiratory System and its Disorders

[0002] The respiratory system of the body facilitates gas exchange. The nose and mouth form the entrance to the airways of a patient.

[0003] 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 “ Respiratory Physiology”, by John B. West, Lippincott Williams & Wilkins, 9th edition published 2012.

[0004] A range of respiratory disorders exist. Certain disorders may be characterised by particular events, e.g. apneas, hypopneas, and hyperpneas.

[0005] 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.

[0006] Obstructive Sleep Apnea (OSA), a form of Sleep Disordered Breathing (SDB), is characterised by events including occlusion or obstruction of the upper airpassage during sleep. It results from a combination of an abnormally small upper airway and the normal loss of muscle tone in the region of the tongue, soft palate and posterior oropharyngeal wall during sleep. The condition causes the affected patient to stop breathing for periods typically of 30 to 120 seconds in duration, sometimes 200 to 300 times per night. It often causes excessive daytime somnolence, and it may cause cardiovascular disease and brain damage. The syndrome is a common disorder, particularly in middle aged overweight males, although a person affected may have no awareness of the problem. See US Patent No. 4,944,310 (Sullivan).

[0007] Cheyne-Stokes Respiration (CSR) is another form of sleep disordered breathing. CSR is a disorder of a patient's respiratory controller in which there are rhythmic alternating periods of waxing and waning ventilation known as CSR cycles. CSR is characterised by repetitive de-oxygenation and re-oxygenation of the arterial blood. It is possible that CSR is harmful because of the repetitive hypoxia. In some patients CSR is associated with repetitive arousal from sleep, which causes severe sleep disruption, increased sympathetic activity, and increased afterload. See US Patent No. 6,532,959 (Berthon- Jones).

[0008] Respiratory failure is an umbrella term for respiratory disorders in which the lungs are unable to inspire sufficient oxygen or exhale sufficient CO2 to meet the patient’s needs. Respiratory failure may encompass some or all of the following disorders.

[0009] A patient with respiratory insufficiency (a form of respiratory failure) may experience abnormal shortness of breath on exercise.

[0010] Obesity Hyperventilation Syndrome (OHS) is defined as the combination of severe obesity and awake chronic hypercapnia, in the absence of other known causes for hypoventilation. Symptoms include dyspnea, morning headache and excessive daytime sleepiness.

[0011] Chronic Obstructive Pulmonary Disease (COPD) encompasses any of a group of lower airway diseases that have certain characteristics in common. These include increased resistance to air movement, extended expiratory phase of respiration, and loss of the normal elasticity of the lung. Examples of COPD are emphysema and chronic bronchitis. COPD is caused by chronic tobacco smoking(primary risk factor), occupational exposures, air pollution and genetic factors. Symptoms include: dyspnea on exertion, chronic cough and sputum production.

[0012] Neuromuscular Disease (NMD) is a broad term that encompasses many diseases and ailments that impair the functioning of the muscles either directly via intrinsic muscle pathology, or indirectly via nerve pathology. Some NMD patients are characterised by progressive muscular impairment leading to loss of ambulation, being wheelchair-bound, swallowing difficulties, respiratory muscle weakness and, eventually, death from respiratory failure. Neuromuscular disorders can be divided into rapidly progressive and slowly progressive: (i) Rapidly progressive disorders: Characterised by muscle impairment that worsens over months and results in death within a few years (e.g. Amyotrophic lateral sclerosis (ALS) and Duchenne muscular dystrophy (DMD) in teenagers); (ii) Variable or slowly progressive disorders: Characterised by muscle impairment that worsens over years and only mildly reduces life expectancy (e.g. Limb girdle, Facioscapulohumeral and Myotonic muscular dystrophy). Symptoms of respiratory failure in NMD include: increasing generalised weakness, dysphagia, dyspnea on exertion and at rest, fatigue, sleepiness, morning headache, and difficulties with concentration and mood changes.

[0013] Chest wall disorders are a group of thoracic deformities that result in inefficient coupling between the respiratory muscles and the thoracic cage. The disorders are usually characterised by a restrictive defect and share the potential of long term hypercapnic respiratory failure. Scoliosis and / or kyphoscoliosis may cause severe respiratory failure. Symptoms of respiratory failure include: dyspnea on exertion, peripheral oedema, orthopnea, repeated chest infections, morning headaches, fatigue, poor sleep quality and loss of appetite.

[0014] A range of therapies have been used to treat or ameliorate such conditions. Furthermore, otherwise healthy individuals may take advantage of such therapies to prevent respiratory disorders from arising. However, these have a number of shortcomings.1.2.2 Therapies

[0015] 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.1.2.2.1 Respiratory pressure therapies

[0016] 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).

[0017] 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.1.2.3 Respiratory Therapy Systems

[0018] 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.

[0019] 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.

[0020] Another form of therapy system is a mandibular repositioning device.1.2.3.1 Patient Interface

[0021] 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 ambientpressure to effect therapy, e.g., at a positive pressure of about 10 cmFFO 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 10 cmJUO. 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] The design of a patient interface presents a number of challenges. The face has a complex three-dimensional shape. The size and shape of noses and heads varies considerably between individuals. Since the head includes bone, cartilage and soft tissue, different regions of the face respond differently to mechanical forces. The jaw or mandible may move relative to other bones of the skull. The whole head may move during the course of a period of respiratory therapy.

[0027] As a consequence of these challenges, some masks suffer from being one or more of obtrusive, aesthetically undesirable, costly, poorly fitting, difficult to use, and uncomfortable especially when worn for long periods of time or when a patient is unfamiliar with a system. Wrongly sized masks can give rise to reduced compliance, reduced comfort and poorer patient outcomes. Masks designed solely for aviators, masks designed as part of personal protection equipment (e.g. filter masks), SCUBAmasks, or for the administration of anaesthetics may be tolerable for their original application, but nevertheless such masks may be undesirably uncomfortable to be worn for extended periods of time, e.g., several hours. This discomfort may lead to a reduction in patient compliance with therapy. This is even more so if the mask is to be worn during sleep.

[0028] 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.

[0029] 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.

[0030] For these reasons, patient interfaces for delivery of CPAP during sleep form a distinct field.1.2.3.1.1 Seal-forming structure

[0031] 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 on the effectiveness and comfort of the patient interface.

[0032] A patient interface may be partly characterised according to the design intent of where the seal-forming structure is to engage with the face in use. In one form of patient interface, a seal-forming structure may comprise a first sub-portion to form a seal around the left naris and a second sub-portion to form a seal around the right naris. In one form of patient interface, a seal-forming structure may comprise a single element that surrounds both nares in use. Such single element may be designed to for example overlay an upper lip region and a nasal bridge region of a face. In one form of patient interface a seal-forming structure may comprise an element that surrounds a mouth region in use, e.g. by forming a seal on a lower lip region of a face. In one form of patient interface, a seal-forming structure may comprise a singleelement that surrounds both nares and a mouth region in use. These different types of patient interfaces may be known by a variety of names by their manufacturer including nasal masks, full-face masks, nasal pillows, nasal puffs and oro-nasal masks.

[0033] A seal-forming structure that may be effective in one region of a patient’s face may be inappropriate in another region, e.g. because of the different shape, structure, variability and sensitivity regions of the patient’s face. For example, a seal on swimming goggles that overlays a patient’s forehead may not be appropriate to use on a patient’s nose.

[0034] Certain seal-forming structures may be designed for mass manufacture such that one design is able to fit and be comfortable and effective for a wide range of different face shapes and sizes. To the extent to which there is a mismatch between the shape of the patient’s face, and the seal-forming structure of the mass- manufactured patient interface, one or both must adapt in order for a seal to form.

[0035] One type of seal-forming structure extends around the periphery of the patient interface, and is intended to seal against the patient's face when force is applied to the patient interface with the seal-forming structure in confronting engagement with the patient's face. The seal-forming structure may include an air or fluid filled cushion, or a moulded or formed surface of a resilient seal element made of an elastomer such as a rubber. With this type of seal-forming structure, if the fit is not adequate, there will be gaps between the seal-forming structure and the face, and additional force will be required to force the patient interface against the face in order to achieve a seal.

[0036] Another type of seal-forming structure incorporates a flap seal of thin material positioned about the periphery of the mask so as to provide a self-sealing action against the face of the patient when positive pressure is applied within the mask. Like the previous style of seal forming portion, if the match between the face and the mask is not good, additional force may be required to achieve a seal, or the mask may leak. Furthermore, if the shape of the seal-forming structure does not match that of the patient, it may crease or buckle in use, giving rise to leaks.

[0037] Another type of seal-forming structure may comprise a friction-fit element, e.g. for insertion into a naris, however some patients find these uncomfortable.

[0038] Another form of seal-forming structure may use adhesive to achieve a seal. Some patients may find it inconvenient to constantly apply and remove an adhesive to their face.

[0039] A range of patient interface seal-forming structure technologies are disclosed in the following patent applications, assigned to ResMed Limited: WO 1998 / 004,310; WO 2006 / 074,513; WO 2010 / 135,785.

[0040] 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 US Patent 4,782,832 (Trimble et al.), assigned to Puri tan -Bennett Corporation.

[0041] ResMed Limited has manufactured the following products that incorporate nasal pillows: SWIFTTM nasal pillows mask, SWIFTTM II nasal pillows mask, SWIFTTM LT nasal pillows mask, SWIFTTM FX nasal pillows mask and MIRAGE LIBERTYTM full-face mask. The following patent applications, assigned to ResMed Limited, describe examples of nasal pillows masks: International Patent Application W02004 / 073,778 (describing amongst other things aspects of the ResMed Limited SWIFTTM nasal pillows), US Patent Application 2009 / 0044808 (describing amongst other things aspects of the ResMed Limited SWIFTTM LT nasal pillows); International Patent Applications WO 2005 / 063,328 and WO 2006 / 130,903 (describing amongst other things aspects of the ResMed Limited MIRAGE LIBERTYTM full-face mask); International Patent Application WO 2009 / 052,560 (describing amongst other things aspects of the ResMed Limited SWIFTTM FX nasal pillows).1.2.3.1.2 Positioning and stabilising

[0042] 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.

[0043] One technique is the use of adhesives. See for example US Patent Application Publication No. US 2010 / 0000534. However, the use of adhesives may be uncomfortable for some.

[0044] Another technique is the use of one or more straps and / or stabilising harnesses. Many such straps / harnesses suffer from being one or more of ill-fitting, bulky, uncomfortable and awkward to use. Where they cover the skin, this may cause discomfort, particularly if they interfere with the skin’s function, e.g. lacking breathability (the ability for moisture from the skin to evaporate). Some headgear straps can be stiff and consequently uncomfortable to wear. The edges of headgear may cause discomfort, for example if they are hard or sharp, and may cause facial marking. Some arrangements of straps can be confusing, for example it may be difficult for the patient to discern which position and / or orientation the straps should be in when worn, or it may be difficult to discern which side is intended to be worn against the patient’s face and which side should face outwardly. Furthermore, patients have heads of different shapes and sizes and an arrangement of straps / harnesses that fit one patient may not fit another. Still further, some strap arrangements have different sections connected together using joints, which may be aesthetically displeasing and may also be in contact with the patient’s skin during use, which can cause discomfort / facial marking. In addition, the manufacturing process for some conventional headgear straps may be energy inefficient.1.2.3.1.3 Pressurised Air Conduit

[0045] In one type of treatment system, a flow of pressurised air is provided to a patient interface through a conduit in an air circuit that fluidly connects to the patient interface so that, when the patient interface is positioned on the patient’s face during use, the conduit extends out of the patient interface forwards away from the patient’s face. This may sometimes be referred to as a “tube down” configuration.

[0046] Some patients find such interfaces to be unsightly or to create a feeling of claustrophobia and are consequently deterred from wearing them, reducing patient compliance. Additionally, conduits connecting to an interface at the front of a patient’s face may sometimes be vulnerable to becoming tangled up in bed clothes.1.2.3.2 Respiratory Pressure Therapy (RPT) Device

[0047] 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.1.2.3.3 Air circuit

[0048] 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.1.2.3.4 Humidifier

[0049] 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.1.2.3.5 Vent technologies

[0050] 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.2 BRIEF SUMMARY OF THE TECHNOLOGY

[0051] 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.

[0052] A first aspect of the present technology relates to apparatus used in the screening, diagnosis, monitoring, amelioration, treatment or prevention of a respiratory disorder.

[0053] Another aspect of the present technology relates to methods used in the screening, diagnosis, monitoring, amelioration, treatment or prevention of a respiratory disorder.

[0054] 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.

[0055] An aspect of certain forms of the present technology is a strap for a positioning and stabilising structure for a patient interface.

[0056] According to one aspect of technology there is provided a strap for a positioning and stabilising structure for a patient interface configured to deliver breathable gas at a therapeutic pressure of at least 4 cmffO above ambient air pressure to an entrance to a patient’s airways. The strap may comprise a patient-facing layer configured to face towards a patient during use. The strap may further comprise a non-patient-facing layer configured to face away from the patient during use. The strap may further comprise a middle layer positioned between the patient-facing layer and the non-patient-facing layer. The strap may further comprise a first bonding layer bonding the patient-facing layer and the middle layer together. The strap may further comprise a second bonding layer bonding the non-patient-facing layer and the middle layer together.

[0057] In certain forms, a patient-facing side of the patient-facing layer may have a different texture to a non-patient-facing side of the non-patient-facing layer.

[0058] In certain forms, the middle layer may comprise a spacer fabric or foam.

[0059] In certain forms, the first bonding layer may comprise a first thermoplastic elastomer film.

[0060] In certain forms, the second bonding layer may comprise a second thermoplastic elastomer film.

[0061] In certain forms, the first thermoplastic elastomer film and / or the second thermoplastic elastomer film may comprise perforations.

[0062] In certain forms, the strap may comprise a central region flanked by one or more edge regions. The central region may be thicker than the edge regions. For example, the middle layer may be thicker in the central region than the edge regions.

[0063] In certain forms, the strap may further comprise one or more edge layers positioned along one of the edge regions. A first edge of each of the edge layers may be joined to a non-patient-facing side of the non-patient-facing layer and a second edge of each of the edge layers may be joined to a patient-facing side of the patientfacing layer. Each edge layer may wrap around a lateral edge of the respective edge region.

[0064] According to one aspect of technology there is provided a strap for a positioning and stabilising structure for a patient interface configured to deliver breathable gas at a therapeutic pressure of at least 4 cmFFO above ambient air pressure to an entrance to a patient’s airways. The strap may comprise one or more layers assembled as a strap body. The strap may further comprise one or more edge layers, each positioned along an edge region of the strap body. A first edge of each of the edge layers may be joined to a non-patient-facing side of the strap body and a second edge of each of the edge layers may be joined to a patient-facing side of the strap body. Each edge layer may wrap around a lateral edge of the respective edge region.

[0065] According to one aspect of technology there is provided a strap for a positioning and stabilising structure for a patient interface configured to deliver breathable gas at a therapeutic pressure of at least 4 cmEEO above ambient air pressure to an entrance to a patient’s airways. The strap may comprise an inner layer. The strap may further comprise an outer layer substantially or partially wrapped around the inner layer. The inner layer and the outer layer may be arranged to form a void between each lateral edge of the inner layer and an inner surface of the outer layer.

[0066] In certain forms, the outer layer may comprise a central region and two edge regions flanking the central region. The central region may be positioned on apatient-facing side of the inner layer and the outer layer may be wrapped around the inner layer so that the edge regions are on a non-patient-facing side of the inner layer.

[0067] In certain forms, the strap may further comprise a non-patient-facing layer on a non-patient-facing side of the outer layer.

[0068] In certain forms, the inner layer may comprise a heat-activated material.

[0069] In certain forms, the inner layer may be a first inner layer and the outer layer may be a first outer layer. The strap may further comprise a second inner layer and a second outer layer substantially or partially wrapped around the second inner layer. The second inner layer and the second outer layer may be arranged to form a void between each lateral edge of the second inner layer and an inner surface of the second outer layer. A patient-facing side of the second outer layer may be joined directly or indirectly to a non-patient-facing side of the first outer layer.

[0070] In certain forms, the second inner layer may comprise a heat-activated material.

[0071] In certain forms, the strap may further comprise a bonding layer between the first outer layer and the second outer layer. For example, the bonding layer may comprise a heat-activated material.

[0072] In certain forms, the strap may have substantially straight edges in plan view when the strap is laid flat. Alternatively, the strap may have substantially curved edges in plan view. In certain forms, the strap may comprise one or more darts and / or cut-outs in the substantially curved edges.

[0073] According to one aspect of technology there is provided a positioning and stabilising structure for a patient interface configured to deliver breathable gas at a therapeutic pressure of at least 4 cmFFO above ambient air pressure to an entrance to a patient’s airways. The positioning and stabilising structure may comprise one or more straps in accordance with another aspect of the technology.

[0074] In certain forms, the one or more straps may comprise a first strap and a second strap, wherein the first strap has a different stiffness from the second strap.

[0075] In certain forms, one or more of the bonding layers of the first strap may have a different stiffness from the one or more bonding layers of the second strap.

[0076] In certain forms, the one or more bonding layers of the first strap may comprise a different arrangement of gaps from the one or more bonding layers of the second strap.

[0077] In certain forms, the one or more straps may comprise a rear portion configured to overlie a posterior region of a patient’s head in use.

[0078] In certain forms, the rear portion may comprise the thicker central region and the thinner edge regions.

[0079] In certain forms, the rear portion may comprise the one or more edge layers.

[0080] According to one aspect of technology there is provided a patient interface comprising a plenum chamber pressurisable to a therapeutic pressure of at least 4 cmfhO above ambient air pressure. The plenum chamber may include a plenum chamber inlet port sized and structured to receive a flow of air at the therapeutic pressure for breathing by a patient. The patient interface may further comprise a sealforming structure constructed and arranged to form a seal with a region of the patient’s face surrounding an entrance to the patient’s airways. The seal-forming structure may have a hole therein such that the flow of air at said therapeutic pressure is delivered to at least an entrance to the patient’s nares. The seal-forming structure may be constructed and arranged to maintain said therapeutic pressure in the plenum chamber throughout the patient’s respiratory cycle in use. The patient interface may further comprise a vent to allow a continuous flow of gases exhaled by the patient from an interior of the plenum chamber to ambient. The vent may be sized and shaped to maintain the therapeutic pressure in the plenum chamber in use. The patient interface may further comprise a positioning and stabilising structure in accordance with another aspect of the technology.

[0081] According to one aspect of technology there is provided a method of forming a strap for a positioning and stabilising structure for a patient interface. The method may comprise forming an assembly of a patient-facing layer, a non-patient-facing layer, a middle layer positioned between the patient-facing layer and the nonpatient-facing layer, a first bonding layer positioned between the patient-facing layer and the middle layer, and a second bonding layer positioned between the non-patientfacing layer and the middle layer. The method may further comprise heating the assembly to cause the first bonding layer to bond the patient-facing layer and the middle layer together and to cause the second bonding layer to bond the non-patientfacing layer and the middle layer together.

[0082] In certain forms, the method may further comprise thermoforming the assembly further forms the strap into a non-planar shape.

[0083] In certain forms, the method may further comprise pressing one or more edge regions of the strap to cause a central region of the strap flanked by the edge regions to be thicker than the edge regions.

[0084] In certain forms, the step of pressing the one or more edge regions may comprise heat pressing the one or more edge regions.

[0085] In certain forms, the method may further comprise positioning one or more edge layers along one or more edge regions of the strap. A first edge of each of the edge layers may be joined to a non-patient-facing side of the non-patient-facing layer and a second edge of each of the edge layers may be joined to a patient-facing side of the patient-facing layer. Each edge layer may wrap around a lateral edge of the respective edge region.

[0086] According to one aspect of technology there is provided a method of forming a strap for a positioning and stabilising structure for a patient interface. The method may comprise forming a plurality of layers into a strap body. The method may further comprise positioning one or more edge layers along respective edge regions of the strap body by joining a first edge of each of the edge layers to a nonpatient-facing side of the strap body and joining a second edge of each of the edge layers to a patient-facing side of the strap body. Each edge layer may wrap around a lateral edge of the respective edge region.

[0087] According to one aspect of technology there is provided a method of forming a strap for a positioning and stabilising structure for a patient interface. Themethod may comprise substantially or partially wrapping an outer layer around an inner layer. The inner layer and the outer layer may be arranged to form a void between each lateral edge of the inner layer and an inner surface of the outer layer.

[0088] In certain forms, the method may further comprise positioning a central region of the outer layer on a patient-facing side of the inner layer and positioning edge regions of the outer layer that flank the central region on a non-patient-facing side of the inner layer.

[0089] In certain forms, the method may further comprise positioning a nonpatient-facing layer on a non-patient-facing side of the outer layer.

[0090] According to one aspect of technology there is provided a strap for a positioning and stabilising structure for a patient interface configured to deliver breathable gas at a therapeutic pressure of at least 4 cmlEO above ambient air pressure to an entrance to a patient’s airways. The strap may comprise a first layer, a second layer, and a bonding layer positioned between and bonding together the first and second layers. The may be gaps in the bonding layer.

[0091] In certain forms, the bonding layer may comprise a thermoplastic elastomer film comprising perforations. In other forms, the bonding layer may comprise an adhesive arranged in a repeating pattern. The repeating pattern may comprise any one or more of: dots; lines; and a net.

[0092] According to one aspect of technology there is provided a positioning and stabilising structure for a patient interface configured to deliver breathable gas at a therapeutic pressure of at least 4 cmEEO above ambient air pressure to an entrance to a patient’s airways. The positioning and stabilising structure may comprise one or more straps according to another aspect of the technology.

[0093] According to one aspect of technology there is provided a positioning and stabilising structure for a patient interface configured to deliver breathable gas at a therapeutic pressure of at least 4 cmEEO above ambient air pressure to an entrance to a patient’s airways. The positioning and stabilising structure may comprise a first strap and a second strap. Each of the first strap and the second strap may comprise a first layer, a second layer, and a bonding layer positioned between and bondingtogether the first and second layers. There may be gaps in the bonding layer. The bonding layer of the first strap may have gaps in a first arrangement and the bonding layer of the second strap may have gaps in a second arrangement. The first arrangement mya be different from the second arrangement.

[0094] In certain forms, the first and second arrangements may form respective repeating patterns in the bonding layers. For example, the repeating patterns may comprise any one or more of dots; lines; and a net.

[0095] In certain forms, a gap density of the first arrangement may be different from a gap density of the second arrangement.

[0096] In certain forms, the positioning and stabilising structure may be arranged such that the first strap is a portion selected from: a rear portion; a superior portion or a side portion of the positioning and stabilising structure, and the second strap may be a different portion selected from the same list of portions.

[0097] In certain forms, at least one of the first and second straps may comprise a third layer. The bonding layer of each strap may be a first bonding layer and each strap may comprise a second bonding layer, positioned between and bonding together the second and third layers. There may be gaps in the second bonding layer.

[0098] In certain forms, an arrangement of gaps in the first bonding layer may be the same as an arrangement of gaps in the second bonding layer. Alternatively, an arrangement of gaps in the first bonding layer may be different from an arrangement of gaps in the second bonding layer.

[0099] According to one aspect of technology there is provided a method of forming a positioning and stabilising structure for a patient interface. The method may comprise forming a first strap by bonding a first layer to a second layer using an intermediate bonding layer. There may be gaps in the bonding layer in a first arrangement. The method may further comprise forming a second strap by bonding a first layer to a second layer using an intermediate bonding layer. There may be gaps in the bonding layer in a second arrangement. The first arrangement may be different from the second arrangement.

[0100] In certain forms, the method may comprise forming the first and second arrangements of gaps with respective repeating patterns in the bonding layers. For example, the repeating patterns may comprise any one or more of: dots; lines; and a net.

[0101] In certain forms, the method may comprise forming the first arrangement of gaps with a gap density that is different from a gap density of the second arrangement.

[0102] In certain forms, the method comprises forming the positioning and stabilising structure such that the first strap is a portion selected from: a rear portion; a superior portion or a side portion of the positioning and stabilising structure, and the second strap may be a different portion selected from the same list of portions.

[0103] In certain forms, the method further comprises forming at least one of the first and second straps with a third layer. The bonding layer of each strap may be a first bonding layer and the method may further comprise forming each strap by bonding the second layer to the third layer using an intermediate second bonding layer. There may be gaps in the second bonding layer.

[0104] In certain forms, the method may comprise forming the first bonding layer with an arrangement of gaps that is the same as an arrangement of gaps in the second bonding layer. Alternatively, the method may comprise forming the first bonding layer with an arrangement of gaps that is different from an arrangement of gaps in the second bonding layer.

[0105] According to one aspect of technology there is provided a strap for a positioning and stabilising structure for a patient interface configured to deliver breathable gas at a therapeutic pressure of at least 4 cmFFO above ambient air pressure to an entrance to a patient’s airways. The strap may comprise a layer comprising a central region flanked by first and second edge regions. The layer may have a first side and a second side opposite the first side. The second sides of the first and second edge regions may be bonded to the second side of the central region with two folded edges being formed between the central region and respective edge regions on respective lateral edges of the strap.

[0106] In certain forms, the strap may further comprise an inner bonding layer substantially covering the second side of the first layer and bonding the second sides of the first and second edge regions to the second side of the central region.

[0107] In certain forms, the inner bonding layer may comprise a thermoplastic elastomer film.

[0108] In certain forms, the first and second edge regions may be arranged such that edges of the first and second edge regions meet or are in close proximity over the second side of the central region.

[0109] In certain forms, the strap may further comprise a non-patient-facing layer bonded to the first side of the first and second edge regions. The non-patient-facing layer may span across a gap or abutment between the first and second edge regions.

[0110] According to one aspect of technology there is provided a method of forming a strap for a positioning and stabilising structure for a patient interface. The strap may comprise a layer comprising a central region flanked by first and second edge regions. The layer may have a first side and a second side opposite the first side. The method may comprise folding the layer to bring the second side of the first edge region into contact with the second side of the central region and forming a first folded edge on a first lateral edge of the strap. The method may further comprise folding the layer to bring the second side of the first edge region into contact with the second side of the central region and forming a second folded edge on a second lateral edge of the strap. The method may further comprise bonding the second side of the first edge region with the second side of the central region. The method may further comprise bonding the second side of the second edge region with the second side of the central region.

[0111] In certain forms, the method may further comprise bonding an inner bonding layer to the second side of the layer to substantially cover the second side of the layer prior to folding the layer.

[0112] In certain forms, the method may further comprise arranging the first and second edge regions such that edges of the first and second edge regions meet or are in close proximity over the second side of the central region.

[0113] In certain forms, the method may further comprise bonding a non-patientfacing layer to the first side of the first and second edge regions to span across a gap or abutment between the first and second edge regions.

[0114] According to another aspect of the technology there is provided a strap for a positioning and stabilising structure for a patient interface, the strap comprising a first layer and a second layer, wherein the first layer is adhered to the second layer using a thermal lamination process.

[0115] According to another aspect of the technology there is provided a method for forming a strap for a positioning and stabilising structure for a patient interface, the method comprising adhering a first layer to a second layer using a thermal lamination process.

[0116] 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.

[0117] 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.

[0118] Of course, portions of the aspects may form sub-aspects of the present technology. Also, various ones of the sub-aspects and / or aspects may be combined in various manners and also constitute additional aspects or sub-aspects of the present technology.

[0119] Other features of the technology will be apparent from consideration of the information contained in the following detailed description, abstract, drawings and claims.3 BRIEF DESCRIPTION OF THE DRAWINGS

[0120] The present technology is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings, in which like reference numerals refer to similar elements including:3.1 RESPIRATORY THERAPY SYSTEMS

[0121] Fig. 1 A shows a system including a patient 1000 wearing a patient interface 3000, in the form of nasal pillows, receiving a supply of air at positive pressure from an RPT device 4000. Air from the RPT device 4000 is humidified in a humidifier 5000, and passes along an air circuit 4170 to the patient 1000. A bed partner 1100 is also shown. The patient is sleeping in a supine sleeping position.

[0122] Fig. IB shows a system including a patient 1000 wearing a patient interface 3000, in the form of a nasal mask, receiving a supply of air at positive pressure from an RPT device 4000. Air from the RPT device is humidified in a humidifier 5000, and passes along an air circuit 4170 to the patient 1000.

[0123] Fig. 1C shows a system including a patient 1000 wearing a patient interface 3000, in the form of a full -face mask, receiving a supply of air at positive pressure from an RPT device 4000. Air from the RPT device is humidified in a humidifier 5000, and passes along an air circuit 4170 to the patient 1000. The patient is sleeping in a side sleeping position.3.2 RESPIRATORY SYSTEM AND FACIAL ANATOMY

[0124] Fig. 2 A shows an overview of a human respiratory system including the nasal and oral cavities, the larynx, vocal folds, oesophagus, trachea, bronchus, lung, alveolar sacs, heart and diaphragm.

[0125] Fig. 2B shows a view of a human upper airway including the nasal cavity, nasal bone, lateral nasal cartilage, greater alar cartilage, nostril, lip superior, lip inferior, larynx, hard palate, soft palate, oropharynx, tongue, epiglottis, vocal folds, oesophagus and trachea.

[0126] Fig. 2C is a front view of a face with several features of surface anatomy identified including the lip superior, upper vermilion, lower vermilion, lip inferior,mouth width, endocanthion, a nasal ala, nasolabial sulcus and cheilion. Also indicated are the directions superior, inferior, radially inward and radially outward.

[0127] Fig. 2D is a side view of a head with several features of surface anatomy identified including glabella, sellion, pronasale, subnasale, lip superior, lip inferior, supramenton, nasal ridge, alar crest point, otobasion superior and otobasion inferior. Also indicated are the directions superior & inferior, and anterior & posterior.

[0128] Fig. 2E is a further side view of a head. The approximate locations of the Frankfort horizontal and nasolabial angle are indicated. The coronal plane is also indicated.

[0129] Fig. 2F shows a base view of a nose with several features identified including naso-labial sulcus, lip inferior, upper Vermilion, naris, subnasale, columella, pronasale, the major axis of a naris and the midsagittal plane.

[0130] Fig. 2G shows a side view of the superficial features of a nose.

[0131] Fig. 2H shows subcutaneal structures of the nose, including lateral cartilage, septum cartilage, greater alar cartilage, lesser alar cartilage, sesamoid cartilage, nasal bone, epidermis, adipose tissue, frontal process of the maxilla and fibrofatty tissue.

[0132] Fig. 21 shows a medial dissection of a nose, approximately several millimeters from the midsagittal plane, amongst other things showing the septum cartilage and medial crus of greater alar cartilage.

[0133] Fig. 2J shows a front view of the bones of a skull including the frontal, nasal and zygomatic bones. Nasal concha are indicated, as are the maxilla, and mandible.

[0134] Fig. 2K shows a lateral view of a skull with the outline of the surface of a head, as well as several muscles. The following bones are shown: frontal, sphenoid, nasal, zygomatic, maxilla, mandible, parietal, temporal and occipital. The mental protuberance is indicated. The following muscles are shown: digastricus, masseter, sternocleidomastoid and trapezius.

[0135] Fig. 2L shows an anterolateral view of a nose.3.3 PATIENT INTERFACE

[0136] Fig. 3 A shows a patient interface in the form of a nasal mask in accordance with one form of the present technology.

[0137] Fig. 3B shows a view of a patient interface 3000 in accordance with one form of the technology.3.4 RPT DEVICE

[0138] Fig. 4 A shows an RPT device in accordance with one form of the present technology.

[0139] Fig. 4B is a schematic diagram of the pneumatic path of an RPT device in accordance with one form of the present technology. The directions of upstream and downstream are indicated with reference to the blower and the patient interface. The blower is defined to be upstream of the patient interface and the patient interface is defined to be downstream of the blower, regardless of the actual flow direction at any particular moment. Items which are located within the pneumatic path between the blower and the patient interface are downstream of the blower and upstream of the patient interface.3.5 HUMIDIFIER

[0140] Fig. 5A shows an isometric view of a humidifier in accordance with one form of the present technology.

[0141] Fig. 5B shows an isometric view of a humidifier in accordance with one form of the present technology, showing a humidifier reservoir 5110 removed from the humidifier reservoir dock 5130.3.6 POSITIONING AND STABILISING STRUCTURE

[0142] Fig. 6A is a cross-sectional view illustration of a strap 3340 for a positioning and stabilising structure 3300 in accordance with one form of the present technology.

[0143] Fig. 6B is a cross-sectional view illustration of a strap 3340 for a positioning and stabilising structure 3300 in accordance with another form of the present technology.

[0144] Fig. 7A is a cross-sectional view illustration of a step of a method of thermoforming a strap 3340 in accordance with one form of the present technology.

[0145] Fig. 7B is a cross-sectional view illustration of another step of a method of thermoforming a strap 3340 in accordance with one form of the present technology.

[0146] Fig. 7C is a cross-sectional view illustration of another step of a method of thermoforming a strap 3340 in accordance with one form of the present technology.

[0147] Fig. 8A is a cross-sectional view illustration of a strap 3340 for a positioning and stabilising structure 3300 in accordance with another form of the present technology.

[0148] Fig. 8B is a cross-sectional view illustration of a strap 3340 for a positioning and stabilising structure 3300 in accordance with another form of the present technology.

[0149] Fig. 8C is a cross-sectional view illustration of a strap 3340 for a positioning and stabilising structure 3300 in accordance with another form of the present technology.

[0150] Fig. 8D is a cross-sectional view illustration of part of a strap 3340 for a positioning and stabilising structure 3300 in accordance with another form of the present technology.

[0151] Fig. 8E is a cross-sectional view illustration of part of a strap 3340 for a positioning and stabilising structure 3300 in accordance with another form of the present technology.

[0152] Fig. 8F is a cross-sectional view illustration of part of a strap 3340 for a positioning and stabilising structure 3300 in accordance with another form of the present technology.

[0153] Fig. 9 is a cross-sectional view illustration of part of a strap 3340 for a positioning and stabilising structure 3300 in accordance with another form of the present technology.

[0154] Fig. 10A is an exploded perspective view illustration of a length of strap 3340 for a positioning and stabilising structure 3300 in accordance with another form of the present technology.

[0155] Fig. 10B is an exploded perspective view illustration of a length of strap 3340 for a positioning and stabilising structure 3300 in accordance with another form of the present technology.

[0156] Fig. 10C is an exploded perspective view illustration of a length of strap 3340 for a positioning and stabilising structure 3300 in accordance with another form of the present technology.

[0157] Fig. 11 A is an illustration of a joint between several straps on a nonpatient-facing side in accordance with another form of the present technology.

[0158] Fig. 1 IB is an illustration of the joint of Fig. 11A on a patient-facing side.

[0159] Fig. 12A is a plan view illustration of an end region of a side strap 3320 according to one form of the technology.

[0160] Fig. 12B is a plan view illustration of an end region of a side strap 3320 according to another form of the technology.

[0161] Fig. 12C is a plan view illustration of an end region of a side strap 3320 according to another form of the technology.

[0162] Fig. 12D is a plan view illustration of an end region of a side strap 3320 according to another form of the technology.4 DETAILED DESCRIPTION OF EXAMPLES OF THETECHNOLOGY

[0163] Before the present technology is described in further detail, it is to be understood that the technology is not limited to the particular examples describedherein, 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.

[0164] 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.4.1 THERAPY

[0165] 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 1000.

[0166] 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.

[0167] In certain examples of the present technology, mouth breathing is limited, restricted or prevented.4.2 RESPIRATORY THERAPY SYSTEMS

[0168] 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 4000 for supplying a flow of air to the patient 1000 via an air circuit 4170 and a patient interface 3000 or 3800.4.3 PATIENT INTERFACE

[0169] A non-invasive patient interface 3000, such as that shown in Figs. 3A and 3B in accordance with one aspect of the present technology comprises the following functional aspects: a seal-forming structure 3100, a plenum chamber 3200, a positioning and stabilising structure 3300, a vent 3400, one form of connection port 3600 for connection to air circuit 4170, and optionally a forehead support 3700. 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 morefunctional aspects. In use the seal -forming structure 3100 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 1000. The sealed patient interface 3000 is therefore suitable for delivery of positive pressure therapy.

[0170] 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.

[0171] The patient interface 3000 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 above the ambient, for example at least 2, 4, 6, 10, or 20 cmFFO with respect to ambient.4.3.1 Seal-forming structure

[0172] The patient interface 3000 may comprise a seal-forming structure 3100. The seal-forming structure 3100 may be constructed and arranged to form a seal with a region of the patient’s face surrounding an entrance to the patient’s airways. Furthermore, the seal -forming structure 3100 may have a hole therein such that the flow of air at said therapeutic pressure is delivered to at least an entrance to the patient’s nares in use. The seal-forming structure 3100 may be constructed and arranged to maintain the therapeutic pressure in the plenum chamber 3200 throughout the patient’s respiratory cycle in use.

[0173] In one form of the present technology, a seal-forming structure 3100 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 3100 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.

[0174] In one form the target seal -forming region is located on an outside surface of the seal-forming structure 3100.

[0175] In certain forms of the present technology, the seal-forming structure 3100 is constructed from a biocompatible material, e.g. silicone rubber. In other forms the seal-forming structure 3100 comprises a foam undercushion 3110 and a textile membrane portion 3220, as described further below.

[0176] A seal -forming structure 3100 in accordance with the present technology may be constructed from a soft, flexible, resilient material such as silicone.

[0177] In certain forms of the present technology, a system is provided comprising more than one a seal-forming structure 3100, 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 structure 3100 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. However, examples of the technology may be suitable for a large range of heads, and so may be used by patients having a relatively large head and a relatively small head.4.3.1.1 Sealing mechanisms

[0178] 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 3200 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.

[0179] In one form, the seal -forming structure 3100 comprises a sealing flange and a support flange. The sealing flange comprises a relatively thin member with a thickness of less than about 1mm, for example about 0.25mm to about 0.45mm, which extends around the perimeter of the plenum chamber 3200. 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 3200, 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.

[0180] In one form, the seal -forming structure may comprise a compression sealing portion or a gasket sealing portion. In use the compression sealing portion, orthe 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.

[0181] 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.

[0182] 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.4.3.1.2 Nose bridge or nose ridge region

[0183] In one form, the non-invasive patient interface 3000 comprises a sealforming structure that forms a seal in use on a nose bridge region or on a nose-ridge region of the patient's face.

[0184] 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.4.3.1.3 Upper lip region

[0185] In one form, the non-invasive patient interface 3000 comprises a sealforming structure that forms a seal in use on an upper lip region (that is, the lip superior) of the patient's face.

[0186] 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.4.3.1.4 Chin-region

[0187] In one form the non-invasive patient interface 3000 comprises a sealforming structure that forms a seal in use on a chin-region of the patient's face.

[0188] 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.4.3.1.5 Forehead region

[0189] 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.4.3.1.6 Nasal pillows

[0190] In one form the seal-forming structure of the non -invasive patient interface 3000 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.

[0191] 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.4.3.1.7 Nose-only Masks

[0192] In certain forms, the patient interface 3000 comprises a seal-forming structure 3100 configured to seal around an entrance to the patient’s nasal airways but not around the patient’s mouth. The seal-forming structure 3100 may be configured to seal to the patient’s lip superior. The patient interface 3000 may leave the patient’s mouth uncovered. This patient interface 3000 may deliver a supply of air or breathable gas to both nares of patient 1000 and not to the mouth. This type of patient interface may be identified as a nose-only mask.

[0193] One form of nose-only mask according to the present technology is what has traditionally been identified as a “nasal mask”, having a seal-forming structure 3100 configured to seal on the patient’s face around the nose and over the bridge of the nose. A nasal mask may be generally triangular in shape. In one form, the non- invasive patient interface 3000 comprises a seal-forming structure 3100 that forms a seal in use to an upper lip region (e.g. the lip superior), to the patient’s nose bridge or at least a portion of the nose ridge above the pronasale, and to the patient's face on each lateral side of the patient’s nose, for example proximate the patient’s nasolabial sulci. The patient interfaces 3000 shown in Figs. IB and 3A have this type of sealforming structure 3100. This patient interface 3000 may deliver a supply of air or breathable gas to both nares of patient 1000 through a single orifice.

[0194] Another form of nose-only mask may seal around an inferior periphery of the patient’s nose without engaging the user’s nasal ridge. This type of patient interface 3000 may be identified as a “nasal cradle” mask and the seal-forming structure 3100 may be identified as a “nasal cradle cushion”, for example. In one form, for example as shown in Fig. 3B, the seal-forming structure 3100 is configured to form a seal in use with inferior surfaces of the nose around the nares. The sealforming structure 3100 may be configured to seal around the patient’s nares at an inferior periphery of the patient’s nose including to an inferior and / or anterior surface of a pronasale region of the patient’s nose and to the patient’s nasal alae. The sealforming structure 3100 may seal to the patient’s lip superior. The shape of the sealforming structure 3100 may be configured to match or closely follow the underside of the patient’s nose and may not contact a nasal bridge region of the patient’s nose or any portion of the patient’s nose superior to the pronasale. In one form of nasal cradle cushion, the seal-forming structure 3100 comprises a bridge portion dividing the opening into two orifices, each of which, in use, supplies air or breathable gas to a respective one of the patient’s nares. The bridge portion may be configured to contact or seal against the patient’s columella in use. Alternatively, the seal-forming structure 3100 may comprise a single opening to provide a flow or air or breathable gas to both of the patient’s nares.

[0195] In some forms, a nose-only mask may comprise nasal pillows, described above.4.3.1.8 Nose and Mouth Masks

[0196] In one form, the patient interface 3000 comprises a seal-forming structure 3100 configured to seal around an entrance to the patient’s nasal airways and also around the patient’s mouth. The seal -forming structure 3100 may be configured to seal to the patient’s face proximate a chin region. This patient interface 3000 may deliver a supply of air or breathable gas to both nares and to the mouth of patient 1000. This type of patient interface may be identified as a nose and mouth mask.

[0197] One form of nose-and-mouth mask according to the present technology is what has traditionally been identified as a “full-face mask”, having a seal-forming structure 3100 configured to seal on the patient’s face around the nose, below the mouth and over the bridge of the nose. A nose-and-mouth mask may be generally triangular in shape. In one form the patient interface 3000 comprises a seal-forming structure 3100 that forms a seal in use to a patient’s chin-region (which may includethe patient’s lip inferior and / or a region directly inferior to the lip inferior), to the patient’s nose bridge or at least a portion of the nose ridge superior to the pronasale, and to cheek regions of the patient's face. The patient interface 3000 shown in Fig. 1C is of this type. This patient interface 3000 may deliver a supply of air or breathable gas to both nares and mouth of patient 1000 through a single orifice. This type of sealforming structure 3100 may be referred to as a “nose-and-mouth cushion”.

[0198] In another form the patient interface 3000 comprises a seal-forming structure 3100 that forms a seal in use on a patient’s chin region (which may include the patient’s lip inferior and / or a region directly inferior to the lip inferior), to an inferior and / or an anterior surface of a pronasale portion of the patient’s nose, to the alae of the patient’s nose and to the patient’s face on each lateral side of the patient’s nose, for example proximate the nasolabial sulci. The seal-forming structure 3100 may also form a seal against a patient’s lip superior. A patient interface 3000 having this type of seal-forming structure may have a single opening configured to deliver a flow of air or breathable gas to both nares and mouth of a patient, may have an oral hole configured to provide air or breathable gas to the mouth and a nasal hole configured to provide air or breathable gas to the nares, or may have an oral hole for delivering air to the patient’s mouth and two nasal holes for delivering air to respective nares. This type of patient interface 3000 may have a nasal portion and an oral portion, the nasal portion sealing to the patient’s face at similar locations to a nasal cradle mask.

[0199] In a further form of nose and mouth mask, the patient interface 3000 may comprise a seal -forming structure 3100 having a nasal portion comprising nasal pillows and an oral portion configured to form a seal to the patient’s face around the patient’s mouth.

[0200] In some forms, the seal -forming structure 3100 may have a nasal portion that is separate and distinct from an oral portion. In other forms, a seal-forming structure 3100 may form a contiguous seal around the patient’s nose and mouth.

[0201] It is to be understood that the above examples of different forms of patient interface 3000 do not constitute an exhaustive list of possible configurations. In some forms a patient interface 3000 may comprise a combination of different features of the above described examples of nose-only and nose and mouth masks.4.3.2 Plenum chamber

[0202] The plenum chamber 3200 may be formed by a portion of the patient interface 3000 that has 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 portion of the patient interface 3000 forming the plenum chamber 3200 is positioned in close proximity to an adjacent surface of the face. Actual contact with the face is provided by the seal-forming structure 3100. The sealforming structure 3100 may extend in use about the entire perimeter of a portion of the patient interface 3000 forming the plenum chamber 3200. In some forms, the plenum chamber 3200 and the seal-forming structure 3100 are formed from a single homogeneous piece of material.

[0203] In certain forms of the present technology, the plenum chamber 3200 does 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.

[0204] In certain forms of the present technology, the plenum chamber 3200 is formed by one or more components 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.

[0205] In certain forms of the present technology, the plenum chamber 3200 is formed by one or more components 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.4.3.3 Positioning and stabilising structure

[0206] The seal-forming structure 3100 of the patient interface 3000 of the present technology may be held in sealing position in use by the positioning and stabilising structure 3300. The positioning and stabilising structure 3300 may comprise and function as “headgear” since it engages the patient’s head in order to hold the patient interface 3000 in a sealing position.

[0207] In one form the positioning and stabilising structure 3300 provides a retention force at least sufficient to overcome the effect of the positive pressure in the plenum chamber 3200 to lift off the face.

[0208] In one form the positioning and stabilising structure 3300 provides a retention force to overcome the effect of the gravitational force on the patient interface 3000.

[0209] In one form the positioning and stabilising structure 3300 provides a retention force as a safety margin to overcome the potential effect of disrupting forces on the patient interface 3000, such as from tube drag, or accidental interference with the patient interface.

[0210] In one form of the present technology, a positioning and stabilising structure 3300 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 3300 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 3300 comprises at least one strap having a rectangular cross-section. In one example the positioning and stabilising structure 3300 comprises at least one flat strap.

[0211] In one form of the present technology, a positioning and stabilising structure 3300 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.

[0212] In one form of the present technology, a positioning and stabilising structure 3300 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.

[0213] In certain forms of the present technology, a system is provided comprising more than one positioning and stabilizing structure 3300, 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 3300 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. The multiple positioning and stabilising structures 3300 may be configured to interchangeably connect to other components of the patient interface 3000.

[0214] In certain forms, the positioning and stabilising structure 3300 comprises a rear portion 3310, a superior portion 3315 and first and second side portions 3320a and 3320b.4.3.3.1 Rear & superior portions

[0215] The rear portion 3310 of the positioning and stabilising structure 3300 may be configured, in use, to overlie a posterior region of the patient's head. Example rear portions 3310 are shown in Figs. 3 A and 3B, in which the rear portion 3310 is worn over a posterior part of the patient's head during use.

[0216] The superior portion 3315 of the positioning and stabilising structure 3300 may be configured, in use, to overlie a superior region of the patient's head. Example superior portions 3315 are shown in Figs. 3 A and 3B, in which the superior portion 3315 is worn over a superior part of the patient's head during use.

[0217] In certain forms, the rear portion 3310 and / or the superior portion 3315 is bendable and, e.g. non-rigid. An advantage of this is that the respective portion is able to conform to the shape of the patient’s head and may be more comfortable for a patient to lie upon while the patient is sleeping. For example, the rear portion 3310 and / or the superior portion 3315 may each comprise one or more straps.

[0218] In the example of Fig. 3B, the rear portion 3310 comprises an inferior posterior strap portion 3312 and the superior portion 3315 comprises a superior posterior strap portion 3314. The inferior posterior strap portion 3312 may be configured to overlie a middle or inferior region of the posterior part of the patient’s head during use, for example overlying the occipital bone. The superior posterior strap portion 3314 may be configured to overlie a superior region of the posterior part of the patient’s head, for example overlying the parietal bone, and / or may pass substantially over the top of the patient’s head when worn. The inferior posterior strap portion 3312 and the superior posterior strap portion 3314 may be formed as two portions of the same length of strap, for example as is the case in the exemplary form shown in Fig. 3B. Alternatively, the inferior posterior strap portion 3312 and the superior posterior strap portion 3314 may be separate strap portions that are joined together, for example through stitching. In some forms, the inferior posterior strap portion 3312 and the superior posterior strap portion 3314 may be formed as the bifurcated sections of a single strap. In some forms, the inferior posterior strap portion 3312 may be formed as a panel, e.g. a thick strap portion or an element in which thewidth does not differ significantly from the length. The panel may be particularly cushioned in order to promote comfort if the patient rests with the rear of their head in contact with something. In some forms, the inferior posterior strap portion 3312 may be configured to lie over a part of the patient’s occipital bone, and a cushioning panel may be particularly useful in this case.

[0219] In alternative forms, the positioning and stabilising structure 3300 may comprise a single strap that may be positioned both posteriorly and superiorly on the patient’s head. It will be appreciated that such a strap may be referred to as a rear portion or a superior portion dependent on the position it takes on a patient’s head during use. In some forms, the positioning and stabilising structure 3300 may comprise a rear portion 3310 but no superior portion 3315 or vice versa.

[0220] The arrangement of rear portions 3310 and / or superior portions 3315 suitable for a positioning and stabilising structure 3300 in any particular form may be selected based on a number of factors, including how the seal -forming structure 3100 forms a seal against the patient’s face and the direction of the force vectors exerted by the positioning and stabilising structure 3300 desirable to maintain that seal during use.4.3.3.1 Side portions

[0221] As shown by way of example in Figs. 3A and 3B, the positioning and stabilising structure 3300 may also comprise first and second side portions 3320, each of which are configured to extend across a respective cheek region of the patient’s head when the patient interface 3000 is being worn. The first and second side portions 3320 may extend between the rear portion 3310 and the part of the patient interface 3000 at the front of the patient’s face. That is, a posterior end of each of the first and second side portions 3320 may connect to a respective side of the rear portion 3310 and an anterior end of each of the first and second side portions 3320 may connect directly or indirectly to the seal -forming structure 3100. As such, the side portions 3320 may act to transmit a force on the seal-forming structure 3100 towards the patients face, i.e. in a generally posterior direction, in order to maintain the seal forming structure 3100 in a sealed engagement with the patient’s face during use of the patient interface 3000. Consequently, the first and second side portions 3320 may be under tension during use.

[0222] In some forms, the anterior ends of the first and second side portions 3320 may connect directly to the seal -forming structure 3100 while, in other forms, such as that shown in Figs. 3 A and 3B, the anterior ends of the first and second side portions 3320 may connect indirectly to the seal-forming structure 3100. In forms with such an indirect connection, the anterior ends of the first and second side portions 3320 may connect to any other component of the patient interface 3000 in order to transmit a force to the seal-forming structure 3100. That other component may itself be directly or indirectly attached to the seal-forming structure 3100, i.e. there may be a plurality of intermediate components between the anterior ends of the first and second side portions 3320 and the seal-forming structure 3100. In examples, the anterior ends of the first and second side portions 3320 may connect directly to any one or more of: the plenum chamber 3200; a frame or shell; a forehead connector 3700; headgear connectors; headgear arms.

[0223] In some forms, the positioning and stabilising structure 3300 may comprise a single side portion 3320 on each side of the patient’s head. This is the case for the form of the technology shown in Fig. 3B. Such a configuration may be particularly used in the case of a nose-only mask, and in particular a “nasal cradle” mask such as is shown in Fig. 3B, or a nasal pillows mask. In such forms, the positioning and stabilising structure 3300 may comprise first and second side portions 3320 constructed and arranged so that in use at least a portion of an inferior edge of each side portion 3320 passes superior to an otobasion superior of the patient’s head. This is the case with the single side portion 3320 on each side of the patient’s head in the example of Fig. 3B. The posterior end of each side portion 3320 may overlay the patient’s head superior to, and optionally posterior to, the patient’s otobasion superior, in use, for example overlying the temporal bone and / or the parietal bone. In the form shown in Fig. 3B, the anterior end of each side portion 3320 overlie a cheek region.

[0224] In other forms, the positioning and stabilising structure 3300 may comprise multiple side portions 3320 on each side of the patient’s head. For example, in the form shown in Fig. 3 A, each side of the positioning and stabilising structure 3300 comprises a superior side portion and an inferior side portion. This arrangement may be particularly suitable for a nasal mask or for a full-face mask. The superior side portions may be configured to pass superior to an otobasion superior of the patient’s head when the patient interface 3000 is worn, while the additional side portions may be constructed and arranged so that in use at least a portion of a superior edge thereofpasses inferior to an otobasion inferior of the patient’s head and overlays or lies inferior to the occipital bone of the patient’s head.

[0225] In certain forms of the technology, for example as shown in Figs. 3 A and 3B, each of the side portions 3320 may comprise one or more straps. In such forms, the side portions 3320 may be referred to as side straps.4.3.3.3 Construction of headgear straps

[0226] The following section describes the construction of parts of the positioning and stabilising structure 3300 according to certain forms of the technology and, in particular, forms of the technology in which the positioning and stabilising structure 3300 comprises one or more straps. It should be understood that, unless otherwise stated, the forms of straps described in this section may be comprised in any part or parts of the positioning and stabilising structure 3300, for example the rear portion 3310, the superior portion 3315 and / or the side portions 3320, and in some forms all of the positioning and stabilising structure 3300. In some forms of the technology, different portions of the positioning and stabilising structure 3300 may be configured differently, and in some forms, each portion may comprise sub-portions configured differently so that straps having different properties may be utilised in different parts of the positioning and stabilising structure 3300.

[0227] In certain forms, the positioning and stabilising structure 3300 may comprise one or more straps 3340. In some forms, each strap 3340 may comprise one or more layers. The layers may be assembled together in some way to form the strap 3340 with the layers being generally parallel to each other. In use, the layers may be oriented generally parallel to a surface of the patient’s face, e.g. their skin. As it is formed from an assembly of layers, a strap 3340 according to certain forms of the technology may be described as a laminate.

[0228] In some forms, a strap 3340 may be considered to be a flexible component with length significantly longer than its width and its width significantly longer than its thickness. In other forms, the positioning and stabilising structure 3300 may comprise straps 3340 of other shapes and configurations, for example flexible components with a length that is insignificantly longer than, or substantially similar to, its width. For example, the rear portion 3310 of the positioning and stabilising structure 3300 may be a strap 3340 having the shape of a panel. In some exemplary forms, the width of the strap 3340 may be 10 - 30 mm, for example approximately 20mm. In some exemplary forms, the thickness of the strap 3340 may be 1.5 - 3.5 mm, for example approximately 2.5 mm.

[0229] In certain forms of the present technology, one or more straps 3340 may be constructed to be breathable to allow moisture vapour to be transmitted through the strap. Examples of suitable materials are mentioned later.

[0230] In certain forms of the present technology, one or more straps 3340 may be extensible, e.g. resiliently extensible. For example, the strap(s) 3340 may be configured in use to be in tension, and to direct a force to draw the seal-forming structure 3100 into sealing contact with a portion of a patient’s face. Examples of suitable materials are mentioned later.

[0231] Figs. 6A and 6B are cross-sectional view illustrations of straps 3340 that may form part of a positioning and stabilising structure 3300 according to certain forms of the technology. Figs. 10A to 10C are exploded perspective view illustrations of straps 3340 that may form part of a positioning and stabilising structure 3300 according to certain forms of the technology. In these forms, the strap 3340 may comprise a plurality of layers formed into a strap body, for example five layers 3341, 3342, 3343, 3344 and 3345 as illustrated. In alternative forms of the technology, the strap 3340 may comprise a strap body formed of fewer or more layers for example, in certain alternative forms, the strap 3340 may comprise three layers, as described later. Since the strap 3340, when used, is typically positioned with the layers oriented generally parallel to a surface of the patient’s face, each layer may be described as having a patient-facing side and a non-patient-facing side, with these terms describing the sides based on the intended orientation of the strap 3340 with respect to the patient during use. It will be appreciated that at any point in time when the strap 3340 is not being used, or if the strap 3340 is being worn by a patient in a manner other than that intended, the layers may adopt orientations in which their respective sides face in other directions.

[0232] Furthermore, the strap 3340 comprises a layer 3345 that is intended, in use, to be positioned closest to the patient’s face and has one of its sides (specifically, its patient-facing side) exposed on an outer side of the strap 3340. This layer 3345 may consequently be referred to as the patient-facing layer 3345. This layer 3345 may come into contact with the patient’s skin or hair during use. The strap 3340 also comprises a layer 3341 that is intended, in use, to be positioned furthest from the patient’s face and has one of its sides (specifically, its non-patient-facing side)exposed on an outer side of the strap 3340. This layer 3341 may consequently be referred to as the non-patient-facing layer 3341. Again it will be appreciated that at any point in time when the strap 3340 is not being used, or if the strap 3340 is being worn by a patient in a manner other than that intended, the layers may adopt orientations in which they face in other directions.

[0233] The strap 3340 may further comprise a middle layer 3343 positioned between the patient-facing layer 3345 and the non-patient-facing layer 3341. The strap may further comprise a first bonding layer 3344 bonding the patient-facing layer 3345 and the middle layer 3343 together. The first bonding layer 3344 may be positioned between the patient-facing layer 3345 and the middle layer 3343. The strap may further comprise a second bonding layer 3342 bonding the non-patient-facing layer 3341 and the middle layer 3343 together. The second bonding layer 3342 may be positioned between the non-patient-facing layer 3341 and the middle layer 3343. Since each of the first bonding layer 3344, middle layer 3343 and second bonding layer 3342 is sandwiched between two other layers in the strap 3340, none of the sides (i.e. the planar faces) of these layers may be exposed on an outer side of the strap 3340.

[0234] In some forms, the edges of any one or more of the layers may be exposed at the edges of the strap 3340. In other forms, the edges of one or more of the layers, or all of the layers forming the strap body, may be covered, for example bound or wrapped as explained further below.

[0235] In certain forms, a patient-facing side of the patient-facing layer 3345 has a different texture to a non-patient-facing side of the non-patient-facing layer 3341. This may enable a patient (or other user) to easily discern which side of the strap 3340 is intended to be positioned against the face during use, and which side is intended to be positioned facing away from the face during use, helping the patient to orient the positioning and stabilising structure 3300 correctly for donning. In some forms, the difference in the texture between these sides of the respective layers may be achieved by forming the patient-facing layer 3345 and the non-patient-facing layer 3341 out of different materials. In other forms, the patient-facing layer 3345 and the non-patientfacing layer 3341 may be formed from the same material, but a material that has a different texture on each side, and orienting the layers accordingly.

[0236] In some exemplary forms, the patient-facing layer 3345 may be formed from a material that is soft, smooth and / or silky, which may be comfortable for apatient to have in contact with their skin for extended periods of time. The material for the patient-facing layer 3345 may also be resistant to damage, e.g. pilling, fraying, snagging (including to hook-and-loop material), etc. For example, the patient-facing layer 3345 may be formed from a double-knit fabric which may comprise, for example, interlocks, rib knits, Ponte di Roma and double-knit jacquard. Double-knit fabrics may be soft, silk-like, stable in both planar dimensions, and resistant to curling and / or creasing. In other forms, the patient-facing layer 3345 may be formed from a single-knit material. In other forms, the patient-facing layer 3345 may be formed from another fabric.

[0237] As explained, the non-patient-facing layer 3341 may be formed from a different material from the patient-facing layer 3345. There may be less need for the non-patient-facing layer 3341 to be soft since it is not intended to be in contact with the patient’s skin for long periods. In some forms, the non-patient-facing layer 3341 may comprise fabric. In some forms, the layer may comprise a furry non-patientfacing surface, for example the non-patient-facing layer 3341 may be formed from an un-broken loop (UBL) fabric. This may be useful for enabling a hook-and-loop connection between one strap comprised as part of the positioning and stabilising structure 3300 to the non-patient-facing surface of the non-patient-facing layer 3341, for example to secure a strap to another part of the patient interface 3000, for example the plenum chamber 3200. A furry surface of a UBL fabric may feel significantly different in texture to the smooth feel of a double-knit fabric. In some forms, the UBL fabric may be formed from a combination of elastane and nylon, for example approximately 10-20% elastane and approximately 80-90% nylon. In some forms, the UBL fabric may be approximately 200 gsm or heavier, for example approximately 240 gsm or heavier. In other forms, other types of fabric may be used for the nonpatient-facing layer 3341.

[0238] Where a knitted fabric is used for the patient-facing layer 3345 and / or the non-patient-facing layer 3341, in some forms both layers may be configured with a warp knit and in other forms both layers may be configured with a weft knit. In some forms, the patient-facing layer 3345 may have a warp knit and the non-patient-facing layer 3341 may have a weft knit, and it may be vice versa in other forms. A gauge of knit may be selected that is suitable for the desired characteristics of each layer and in some forms, the gauge may be 20 - 50, for example 28 - 40. In some forms, the yam may be draw texturised yarn (DTY), in other forms the yam may be fully drawn yarn(FDY) and in other forms a mixture of the two may be used. Some types of DTY may be considered to be softer and more breathable than some types of FDY.

[0239] The middle layer 3343 may function to provide thickness to the strap 3340. The middle layer 3343 may additionally, or alternatively, provide cushioning. The material(s) used to form the middle layer 3343 may be selected accordingly. In certain forms, the middle layer 3343 may comprise a spacer fabric, for example a monofilament spacer or a multi-filament spacer (which may be understood to comprise spaced-apart fabric layers with an intermediate layer of pile threads formed from a single yam or multiple yarns, respectively). Properties of the middle layer 3343 may be selected in order to arrive at desirable properties, e.g. thickness, softness and resilience. For example, the density of pile threads, the thickness of the threads and the spacing between the fabric layers may be selected to achieve the desired properties. In other forms, the middle layer 3343 may comprise foam, for example polyurethane foam, for example soft-cell polyurethane foam. In some forms, the middle layer 3343 may comprise memory foam, e.g. viscoelastic polyurethane foam, or low-resilience polyurethane foam (LRPu), particularly in a section of strap 3340 positioned to overlay the neck region or the occipital region of the patient’s head in use (although this may be used in other sections of the positioning and stabilising structure 3300 also or instead). The material used for the middle layer 3343 may differ in different parts of the positioning and stabilising structure 3300. For example, in some forms the superior portion 3315 may comprise a middle layer 3343 formed of foam and the side portions 3320 may comprise a middle layer 3343 formed of spacer fabric (or vice versa in other forms). Different types of material, and different properties of material of the same type may be selected for the middle layers 3343 of straps 3340 in different parts of the positioning and stabilising structure 3300 in order to provide desired properties, e.g. breathability, stiffness, cushioning.

[0240] The preceding paragraphs have explained the plurality of layers in the strap body of examples of five-layer straps such as shown in Figs. 6 A, 6B and 10A to 10C. In other forms, the strap 3340 may comprise a strap body comprising only three layers, in which case the strap may comprise a patient-facing layer 3345, a nonpatient-facing layer 3345 and an intermediate bonding layer 3344 in between them to bond the patient-facing layer 3345 and the non-patient-facing layer 3345 together. The descriptions of these layers elsewhere should be understood to apply to forms of straps 3340 comprising three layers also.

[0241] In certain forms, the various layers of the strap 3340 may be configured such that the strap 3340 has force-strain characteristics so that there is approximately 5-8% elongation when a ION force is applied, and approximately 13-16% elongation when a 20N force is applied. The force-strain characteristics of different straps 3340 may vary within a positioning and stabilising structure 3300 and may differ in other forms.

[0242] The straps 3340 of certain forms may be configured, for example may be formed from suitable materials, such that the straps can be regularly washed without significantly effecting their functional performance, and optionally also their physical appearance. In some forms, the straps 3340 may need to maintain such characteristics if washed in warm water using mild liquid detergent and rinsed regularly, for example washed regularly (e.g. weekly) in a washing machine.

[0243] In the form shown in Fig. 6B, the strap 3340 comprises a central region 3348 flanked by one or more edge regions 3349a and 3349b, for example a central region extending along the length of the strap 3340 and an edge region on each lateral side of the central region 3348. The central region 3348of the strap 3340 is thicker than the edge regions 3349a and 3349b. That is, it has a greater dimension in a direction that is a direction up-and-down the page as shown in Fig. 6B, and this direction is generally oriented perpendicular to the surface of the patient’s skin when the strap 3340 is worn in use. The greater thickness of the central region 3348 may be achieved by making one or more of the strap’s layers thicker in that region. For example, in the form of Fig. 6B, the middle layer 3343 is thicker in the central region 3348 than in the edge regions 3349a and 3349b. A strap 3340 with a thicker central region 3348 may be useful for providing enhanced cushioning in certain regions of the positioning and stabilising structure 3300. This may be provided where desired in any particular form of the technology. In some forms, a strap 3340 with a thicker central region 3348, such as described above, may be comprised as part of a rear portion 3310 of the positioning and stabilising structure 3300. For example, a positioning and stabilising structure 3300 may be configured such that a strap 3340 with a thicker central region overlies a patient’s occipital region, for example their occipital bone, or part thereof, during use. The width of the thicker central region 3348, i.e. the extent in a direction that is perpendicular to its length and to its thickness and shown as W in Fig. 6B, may be selected based on the amount of enhanced cushioning desired. In some forms, for example, as shown in Fig. 6B, thewidth of the thicker central region 3348 may be a significant proportion of the width of the strap 3340, for example 70%, 80% or 90%. For example, in forms in which the width of the strap 3340 may be approximately 10 - 30 mm, for example approximately 20 mm, the width W of the thicker central region 3348 may be approximately 7 - 25 mm, for example approximately 16 mm. In other forms, the width of the thicker central region 3348 may be a different proportion of the width of the strap 3440.

[0244] In some forms, the strap 3340 may comprise at least one region which comprises thinner edge regions 3349 on more than two sides of the strap 3340. For example, the strap 3340 may comprise thinner edge regions 3349 substantially surrounding the central thicker region 3351. In some forms a rear portion 3310 of the strap 3340, for example one configured to overlie the patient’s occipital region in use, may be formed as a panel (e.g. a thick strap portion or an element in which the width does not differ significantly from the length) and the panel may have a thicker central region 3348 and thinner edge regions 3349 on two, three or, in some forms, four sides of the panel. In forms in which the panel may be approximately circular or approximately oval, the thinner edge regions 3349 may partially or entirely surround a central thicker region 3351.4.3.3.3.1 Bonding lay er (s)

[0245] It has been described that forms of the technology may comprise one or more bonding layers, for example bonding layer 3344 and optionally bonding layer 3342. The bonding layers may comprise one or more substances suitable for bonding two adjacent layers to each other, and the bonding layers 3342 and 3344 may bond their adjacent layers together through any suitable bonding process. In some forms, the bonding layers may be pre-formed as a thin sheet (for example in the form of a strap) and assembled together with the adjacent layers in order to bond them together, for example upon contact or upon activation of the bonding layer, e.g. by heating (as described below). In other forms, the bonding layer may be formed by adding adhesive to one or both facing sides of the layers to be bonded together. In these forms, the bonding layer may be formed as a contiguous body of adhesive in between the bonded adjacent layers or it may comprise a plurality of non-contiguous bodies of adhesive, i.e. bodies of adhesive separated by gaps (regions devoid of adhesive), in between the bonded adjacent layers.

[0246] In certain forms, either or both of the first bonding layer 3344 and the second bonding layer 3342 may be formed from a heat-activated material. For example, either or both of the first bonding layer 3344 and the second bonding layer 3342 may be formed from a heat-activated plastic. In some forms, the bonding layers may be formed from a thermoplastic while in other forms the bonding layers may be formed from a thermoset, for example a thermoset elastomer film, e.g. polyurethane. In the case of adhesive, a hot melt adhesive, for example a polyurethane reactive (PUR) hot melt adhesive, may be used in some forms. In some exemplary forms, the glue amount of the PUR hot melt adhesive may be in the range 20-80 gsm, e.g. 40-60 gsm. The bonding layer(s) may have a glue line temperature to which the adhesive may need to be heated for effective bonding to adjacent layers to occur. A suitable material for the bonding layer(s) may be selected such that the glue line temperature is substantially less than the softening or melting temperature of any of the other layers of the strap 3340. For example, in forms in which nylon is used to form a layer of strap 3340, or as a constituent of a layer, the glue line temperature of the bonding layer(s) may be less than approximately 150°C (being the softening temperature of nylon).

[0247] The materials forming the first bonding layer 3344 and the second bonding layer 3342 may be the same as each or different from each other. In some examples, either or both of the first bonding layer 3344 and the second bonding layer 3342 may comprise a thermoplastic elastomer film, e.g. thermoplastic polyurethane (TPU). These thermoplastic elastomer films may be the same or different, for example they may possess different properties in some forms of the technology. In some forms, the bonding layers 3342 and 3344 may be approximately 30-100 microns thick, for example.

[0248] In some forms, the one or more bonding layers 3342, 3344 may comprise gaps. For example, in some forms, the sheets, e.g. the thermoplastic elastomer films, used to form one or both of the bonding layers 3342, 3344 may comprise a plurality of holes, for example perforations arranged in an array. Such holes may be formed in the bonding layers 3342, 3344 using a punching process, for example. In other forms, for example as shown in Figs. 10A to 10C, the bonding layers 3342 and 3344 may be formed by applying adhesive to one or both sides of adjacent layers to be bonded together, for example to the patient-facing side of the non-patient-facing layer 3341 and the patient-facing side of the middle layer 3343 (alternatively, or additionally, tothe non-patient-facing side of the middle layer 3343 and / or the non-patient-facing side of the patient-facing layer 3345). The adhesive may be applied so that there are gaps in the adhesive. The adhesive may be applied to respective surfaces in any suitable arrangement, for example it may be applied in a repeating pattern or in a nonrepeating manner, to achieve such gaps. In the example of Fig. 10A, the adhesive is applied as dots (e.g. in a repeating pattern, such as in a grid-like pattern, or randomly). In the example of Fig. 10B, the adhesive is applied as lines, e.g. parallel lines (which may be oriented parallel to the length of the strap 3340 as shown in Fig. 10B or in another orientation, for example parallel to the width of the strap 3340 or diagonally). In the example of Fig. 10C, the adhesive is applied in a net pattern, i.e. two sets of parallel lines in different directions (which may have any suitable orientation relative to the strap and relative to each other).

[0249] The gaps of these exemplary forms of the technology may permit air and / or moisture to pass through the strap 3340, increasing the breathability of the strap 3340. The gaps may affect the stiffness (i.e. stretchability) of the respective bonding layer 3342 / 3344 and, in turn, the respective strap 3340 that comprises the bonding layer. For example, more gaps (i.e. greater density of gaps) and / or larger gaps may provide a lower level of stiffness than fewer (lower density of gaps) / smaller gaps, while providing a higher level of breathability. A higher level of breathability may be useful in forms in which the middle layer 3343 is formed of foam and a thermoforming process is used to form the strap 3340. In such a case, some parts of the foam may melt, which can adversely impact breathability. In addition, different patterns of gaps may affect the stiffness of the layer. The configuration of the gaps in the bonding layer(s) may be selected to provide the strap 3340 with the desired level of stiffness and / or breathability.

[0250] In some forms, different parts of a positioning and stabilising structure 3300 may be formed from straps 3340 having different stiffnesses. One way this may be achieved is by forming one strap with one form of bonding layer and another strap with another type of bonding layer, where the bonding layers have different stiffnesses. For example, the arrangements of the gaps in the different types of bonding layers may be different. In the case of bonding layers in the form of thermoplastic elastomer films containing perforations, the size, density and / or pattern of the perforations may differ between bonding layers. In the case of bonding layers in the form of adhesive applied to surfaces of the strap layers, the pattern of theadhesive may differ between bonding layers, e.g. different patterns as shown in Figs. 10A-C may be used. Alternatively, the type of bonding layer may be different between different straps 3340, for example one strap may comprise bonding layers formed from pre-formed thin sheets (e.g. thermoplastic elastomer films) and another strap may comprise bonding layers formed from adhesive applied to surfaces of the strap layers. Alternatively, or additionally, the material used to form the bonding layer may be different between different straps 3340, e.g. different adhesives or different thermoplastic elastomer films may be used.

[0251] In certain forms of the technology, the side portions 3320 of the positioning and stabilising structure 3300 may be configured to be stiffer than the rear portion 3310 and / or the superior portion 3315. For example, the side portions 3320 may be rigid or semi-rigid while the rear portion 3310 and / or the superior portion 3315 may be substantially flexible. In other forms, the 3315 the side portions 3320 of the positioning and stabilising structure 3300 may be configured to be less stiff than the rear portion 3310 and / or the superior portion.

[0252] In some forms, the bonding layers of the straps 3340 may be configured to have similar or matching force-strain characteristics as those described above. In addition, the bonding between layers should be sufficiently strong that there is no delamination of the layers for the range of forces commonly experienced by a strap 3340 during typical use of a positioning and stabilising structure 3300, and in some forms there may be additional tolerance to particularly high forces. In some exemplary forms, the bonding layers may be configured such that no delamination occurs for forces applied to the straps 3340 under approximately 15N.

[0253] The use of bonding layers such has been described may enable straps 3340 according to certain forms of the technology to be formed without the use of stitches.4.3.3.3.2 Soft edges

[0254] Other forms of the technology are illustrated in Figs. 8A to 8E and will now be described. In these forms, the strap 3340 may comprise an inner layer 3351 and an outer layer 3352. The outer layer 3352 may be substantially or partially wrapped around the inner layer 3351 to enclose or partially surround the inner layer. In particular, the outer layer 3352 may entirely cover the inner layer 3351 on a patient-facing side (i.e. the bottom side in the orientation of the straps in Figs. 8A to8C) and on lateral sides of the inner layer 3351. The outer layer 3352 may additionally entirely or substantially cover the inner layer 3351 on a non-patientfacing side (top side in Figs. 8A to 8C) although, in some forms, the inner layer 3351 may be partially uncovered on a non-patient-facing side. The outer layer 3352 may be wrapped around the inner layer 3351 by placing a central region of the outer layer 3352 adjacent the inner layer 3351 (i.e. on a side of the inner layer 3351 that corresponds to the patient-facing side during use) and folding edge regions of the outer layer 3352 (the edge regions of the outer layer 3352 flanking the central region) around the inner layer 3351 and bringing them together, or towards each other, on the upper side of the inner layer (i.e. the side of the inner layer 3351 that corresponds to the non-patient-facing side during use). In some forms, the gap between the edges of the outer layer 3352 on the upper side of the inner layer 3351 may be a few millimetres, e.g. 1-2 mm.

[0255] The outer layer 3352 and the inner layer 3351 may be arranged such that, when the outer layer 3352 is wrapped around the inner layer 3351, a void 3355 is formed between each lateral edge of the inner layer 3351 and an inner surface of the outer layer 3352. Such voids 3355 are shown in Figs. 8A and 8C, for example. In other words, there is a gap between the outer side edge of the inner layer 3351 and the portion of the outer layer 3352 positioned directly lateral to the edge. In some forms, the size of the voids 3355 may be a few millimetres in width (i.e. in the lateral direction), for example 2-4mm. One purpose of this structure is to provide cushioning to the edge of the strap 3340. As shown in Fig. 8B, when a compressive force is applied to an edge of the strap 3340, for example a lateral compressive force in the case of Fig. 8B, the outer layer 3352 is able to be pushed inwardly into the void 3355. This softens the edge of the strap 3340 and improves comfort for the patient. The outer layer 3352 may be configured to return to its original configuration (as shown in Fig. 8A) once the compressive force is removed, for example the outer layer 3352 may be formed from a resiliently deformable material.

[0256] The softness of the edge provided by these forms may be useful for a strap 3340 in one or multiple regions of a positioning and stabilising structure 3300. In certain forms, the edge softness may be particularly desirable for parts of a positioning and stabilising structure 3300 configured to be positioned in proximity to the patient’s ear during use since a lateral compressive force may be exerted on the strap 3340 by the ear while the patient interface 3000 is being worn. For example, astrap 3340 having such a form could be comprised as part of a side portion 3320, for example superior / anterior parts of a side portion 3320, or a rear portion 3310, for example parts of a rear portion 3310 positioned on the sides of a patient’s head during use.

[0257] The inner layer 3351 may be formed from any suitable material. In some forms, the inner layer 3351 may be formed from a heat-activated material, for example a thermoplastic or a thermoset as explained earlier in relation to bonding layers 3342 and 3344. In certain examples, the inner layer 3351 may be formed from a thermoplastic elastomer film, for example thermoplastic polyurethane (TPU). In other forms, the inner layer 3351 may be formed from other materials, for example a spacer fabric or foam, e.g. polyurethane foam or memory foam, such as explained above in relation to middle layer 3343. In some forms, rubber or fibrefill (for example nonwoven fibrefill or polyester fibrefill) may be used. In some forms, the inner layer 3351 may comprise a plurality of layers, which may include any two or more of the materials already described, or other suitable materials. Any one or more of the layers may be formed from a tape of material. Forms in which the inner layer 3351 does not include any foam may be easier to contour to the desired shape during use since some foams may melt and stiffen during a heating process.

[0258] The outer layer 3352 may be formed from any suitable material. In some forms, the outer layer 3352 may be formed from one or more of any of the materials described earlier in relation to the patient-facing layer 3345. In some forms, the outer layer 3352 may be formed from a resiliently deformable material to return the outer layer to its original form following compression into the void 3355 as described earlier.

[0259] In some forms of the technology, for example as shown in Figs. 8A and 8C, the strap 3340 may further comprise a non-patient-facing layer 3354 on a nonpatient-facing side of the strap 3340, and specifically on a non-patient-facing side of the outer layer 3352. The non-patient-facing layer 3354 may be formed from any of the materials described above in relation to the non-patient-facing layer 3341 of Figs. 6A and 6B. The strap 3340 may further comprise a bonding layer 3353 positioned between the non-patient-facing layer 3354 and the outer layer 3352. The bonding layer 3353 may be formed from a heat-activated material, for example a thermoplastic or a thermoset as explained earlier in relation to bonding layers 3342 and 3344. In certain examples, the bonding layer 3353 may be formed from a thermoplasticelastomer film, for example. In other forms, the non -patient-facing layer 3354 may be joined to the rest of the strap, e.g. to the outer layer 3352, using adhesive.

[0260] In some forms of the technology, for example the form shown in Fig. 8C, a second bundle of inner and outer layers may be provided on a non-patient-facing side of the strap 3340. More specifically, a second inner layer 3356 may be wrapped in a second outer layer 3357, optionally forming voids 3358 in a similar manner to voids 3355 formed by the first inner and outer layers. Similar considerations as have been described in relation to the first inner layer 3351 and first outer layer 3352 may apply to the second inner layer 3356 and second outer layer 3357, although in some forms the material used to form second outer layer 3357 may differ from the material used to form first outer layer 3351, such as has been explained earlier in relation to the form of Figs. 6A and 6B. The patient-facing side of the second outer layer 3357 may be joined to the non-patient-facing side of the first outer layer 3351 in any appropriate manner. In some forms, such as shown in Fig. 8C, a bonding layer 3353 may be positioned between the outer layers and used to join the outer layers in a manner such as previously described (for example, the bonding layer 3353 may be heat-activated). In other forms, an adhesive may be used. The additional bundle on the non-patient-facing side of the strap 3340, such as shown in Fig. 8C, may help to further improve comfort because of the smooth lateral edges presented by second outer layer 3357, although the strap of Fig. 8C may be more complex and costly to manufacture compared to that of Figs. 8A and 8B.

[0261] Figs. 8D and 8E are cross-section view illustrations of parts of straps 3340 according to certain forms of the technology. Fig. 8D illustrates the arrangement of outer layer 3352 and inner layer 3351 of the forms shown in Figs. 8A to 8C (although with other parts of the strap not shown in Fig. 8D). Fig. 8E shows an alternative arrangement of outer layer 3352 and inner layer 3351 according to other forms of the technology. This arrangement may be used instead of the arrangement of Fig. 8D in the forms shown in Figs. 8A to 8C. In the case of both the forms of Figs. 8D and 8E, additional layers may be assembled with the illustrated layers, such as shown in Figs. 8A to 8C. In the case of the form shown in Fig. 8D, the edge regions of the outer layer 3352 (the edge regions of the outer layer 3352 flanking the central region) are folded around the inner layer 3351, bringing them together, or towards each other, on the upper side of the inner layer (i.e. the side of the inner layer 3351 that corresponds to the non-patient-facing side during use). In the case of the form shown in Fig. 8E, theedge regions 3359 of the outer layer 3352 are further folded and tucked inwardly so that the edge regions 3359 are positioned between the inner layer 3351 and other parts of the outer layer 3352, as illustrated. In some forms, the gap between the inner edges of the folds of the outer layer 3352 on the upper side of the inner layer 3351 (i.e. distance W as shown in Fig. 8E) may be a few millimetres, e.g. 1-2 mm. Folding the edge regions 3359 inwardly in this manner may be advantageous to avoid fraying of the edges of the inner layer 3351. The thickness of the strap 3340 may be also increased to an extent which increases the durability of the strap 3340. In addition, the strap 3340 may be advantageously reinforced because the edge regions 3359 folds inwards and runs along the length of the strap 3340. The previously described voids 3355 may also be present in the form shown in Fig. 8E.

[0262] Fig. 8F is a cross-sectional view illustration of a part of a strap 3340 according to certain other forms of the technology. In such forms, the strap 3340 comprises an outer layer 3352, which may be in the form of a strip of any suitable material, such as those described elsewhere in this specification. The outer layer 3352 has a first side and a second side, the second side being opposite the first side. In this context, the first side and the second side refer to the sides of the outer layer 3352 when in an unfolded state. Since the outer layer 3352 is shown in a folded state in Fig. 8F (as explained further below), in the illustrated state the first side may considered to be the outwardly facing side and the second side may be considered to be the inwardly facing side.

[0263] Outer layer 3352 may comprise a central region 3348 flanked by a first edge region 3349a and a second edge region 3349b. The edge regions 3349a and 3349b extend along opposite lateral sides of the central region 3348. The central region 3348 and edge regions 3349a, 3349b may also have first and second sides, corresponding to the first and second sides of the outer layer 3352.

[0264] The strap 3340 may be formed from the outer layer 3352 by folding the first and second edge regions 3349a and 3349b inwardly onto the central region 3348. More particularly, the outer layer 3352 may be folded by placing the second sides of the first and second edge regions 3349a and 3349b in contact with respective parts of the second side of the central region 3348, thus forming a C-shaped or staple-shaped strap 3340 in cross-section. The regions placed in contact with each other may be bonded together in order to maintain the strap 3340 in the folded configuration. The outer lateral edges of the strap 3340 may therefore be folded edges. While these areshown with a square-shaped profile in Fig. 8F, this is a simplified schematic illustration only, and in practice these edges will be generally rounded, and consequently present a rounded, soft edge outwardly. This may be beneficial for patient comfort, including reducing marking on the patient’s face following wearing the patient interface 3000 for an extended period.

[0265] Any suitable bonding technique may be used to bond the edge regions 3349 to the central region 3348. In certain forms, for example as shown in Fig. 8F, the strap 3340 may comprise a bonding layer 3351 that is bonded to the second side of the outer layer 3352. When the outer layer 3352 has been folded, the bonding layer 3351 is consequently positioned inside outer layer 3352. The bonding layer 3351 may occupy any suitable extent over the surface area of the second side of the outer layer 3352 in order to effectively bond the edge regions 3349 to the central region 3348. In some forms, for example as shown in Fig. 8F, the bonding layer 3351 may substantially cover the second side of the central region 3348. In this form, when the edge regions 3349 are bonded to the central region 3348, this may be achieved by bonding the regions of the bonding layer 3351 that are themselves bonded to the edge regions 3349 and the central region 3348 to each other. In other forms, the bonding layer 3351 may be formed of a plurality of non-joined regions of adhesive. The bonding layer 3351 may formed from a thermoplastic elastomer film, e.g. thermoplastic polyurethane (TPU), for example. In other forms, the bonding layer3351 may be formed from another type of adhesive.

[0266] In certain forms of the technology, for example as shown in Fig. 8F, the first and second edge regions 3349a and 3349b may be arranged such that the edges of these regions (i.e. which correspond to the outer lateral edges of the outer layer3352 when in an unfolded configuration) abut or are in close proximity over the second side of the central region 3348. That is, there may be substantially no gap between the edges of the edge regions 3349a and 3349b, or any gap between these edges may be relatively small, e.g. significantly smaller than a width of the strap 3340.

[0267] In some forms of the technology, the side of the folded strap 3340 that has the gap between or meeting of the edges of the edge regions 3349a and 3349b may be the non-patient-facing side when the strap 3340 is used in a positioning and stabilising structure 3300 of a patient interface 3000. This means that the patient-facing side may be free from gaps or abutments and consequently presents the more comfortable sidetowards the patient. In other forms, the strap 3340 may be positioned in the opposite orientation.

[0268] As shown by way of example in Fig. 8F, in some forms of the technology, the strap 3340 may further comprise a non-patient-facing layer 3354 bonded to the non-patient-facing side of the outer layer 3352 in its folded configuration, i.e. to the second (or outward) side of the outer layer 3352, and specifically to the second sides of the first and second edge regions 3349a and 3349b. The non-patient-facing layer 3354 may be bonded to the outer layer 3352 in a position where it spans across the gap or abutment between the first and second edge regions 3349a and 3349b. The non-patient-facing layer 3354 may be useful to cover the gap or abutment, which may be uncomfortable if it comes into contact with the patient’s face or may be aesthetically displeasing. The non-patient-facing layer 3354 may be bonded to the outer layer 3352 in any suitable manner, for example a bonding layer 3353 may be provided on a side of the non-patient-facing layer 3354 nearest the outer layer 3352 (which may be a patient-facing side of the bonding layer 3353 in use). The bonding layer 3353 may formed from a thermoplastic elastomer film, e.g. thermoplastic polyurethane (TPU), for example. In other forms, the bonding layer 3351 may be formed from another type of adhesive.

[0269] The forms of the technology illustrated in Figs. 8A to 8F comprise layers that are described here as outer layers. It should be appreciated that, the term “outer” is used to describe these layers in the sense that they are positioned outside of another layer, for example the respective inner layers, and this does not necessarily mean that all of the outer layer needs to be on the outer side of the strap 3340 as a whole. In fact, it should be apparent from the description and figures that some parts of the outer layers may be internal to the strap 3340.

[0270] In some forms, the forms of strap 3340 described in this section, and for example as illustrated in Figs. 8A to 8F, may be used in portions of the positioning and stabilising structure 3300 in which the strap 3340, or portion of strap, has substantially straight edges in plan view when the strap is laid flat. Wrapping the outer layer 3352 around the inner layer 3351 in the described manner, or folding the edge regions 3349 inwards onto the central region 3348, may be easier to manufacture for such substantially straight sections of strap 3340 compared to if the strap, or section of strap, comprises a substantially curved edge in plan view when laid flat. The location of substantially straight portions of strap 3340 in different positioningand stabilising structures 3300 may differ but, in some forms, the side portions 3320 may have substantially straight edges in plan view when laid flat. The rear portion 3310 and / or the superior portion 3315 may additionally or alternatively have substantially straight edges in plan view when laid flat.

[0271] In other forms, the forms of strap 3340 described in this section, and for example as illustrated in Figs. 8A to 8F, may be used in portions of the positioning and stabilising structure 3300 in which the strap 3340, or portion of strap, has substantially curved edges in plan view. In some forms, the strap 3340 may have substantially curved edges when the strap is laid flat while, in other forms, the strap 3340 may not be able to be laid flat (without bumps or wrinkles occurring), for example the strap 3340 may have the geometry of a surface curved in three- dimensions, e.g. a conic or spherical surface. Providing the strap with such curved edges may add complexity to the manufacturing process, but has the benefit of providing the advantages of the soft edges even where the strap edges are curved. The configuration of the strap 3340 described in relation to Figs. 8A to 8F may be achieved along the length of a strap section in which the edge is substantially curved in plan view through the use of darts and / or cut-outs, for example. Alternatively, or additionally, the layers of the strap 3340 may be temporarily stretched, optionally with the application of heat to elevate the strap 3340 to relatively high temperatures to enable the outer edge of the strap to be stretched more than the inner edge, achieving a curve. This may be achieved in some forms through the use of two rollers operating at different speeds, for example. In some forms, the rear portion 3310 and / or the superior portion 3315 may have substantially curved edges in plan view. The side portions 3320 may additionally or alternatively have substantially curved edges in plan view.4.3.3.3.3 Rigidiser

[0272] In certain forms of the technology, one or more straps 3340 of the positioning and stabilising structure 330 may comprise a rigidiser that, in use, assists in maintaining the seal -forming structure 3100 in an operating position. The rigidiser may be constructed from a rigid material. The rigid material may not permit the strap 3340 of which it is comprised as part to stretch. Additionally, the rigidiser may be substantially inflexible and may be unable to bend. The rigidiser may be pre-molded into a desired shape in order to enable the relevant strap 3340 to fit a patient’s head.For example, the rigidiser may be molded with a curved shape to substantially correspond to the shape of the side of the patient’s head (e.g., overlaying the masseter muscle and / or the temporal bone). In certain forms, the rigidiser may be molded in order to conform to a specific patient’s head (e.g. the rigidiser is customised).

[0273] In some forms, the rigidiser may be flexible along at least one direction. For example, the rigidiser may be flexible about its width and may be inflexible along its length. In other words, the rigidiser may be bendable about an axis along the width of the rigidiser, but may be unable to bend about an axis perpendicular to the rigidiser. This may allow an individual patient to adjust the rigidiser in order to better fit their individual head.

[0274] In certain forms, the rigidiser may remain in the new position after being bent. This may allow a patient to adjust the shape of the rigidiser for their specific head and then the rigidiser will keep the desired shape while in use in order to promote patient comfort.

[0275] In some forms, the rigidiser may be formed from a thermoplastic or thermoset material, for example a thermoplastic elastomer film, e.g. thermoplastic polyurethane (TPU), or a thermoset elastomer film, e.g. polyurethane. For example, any one or more of the bonding layers of a strap 3340 as described elsewhere in this specification may be formed so as to function as a rigidiser. The strap 3340 may be formed so that the rigidiser is embedded within the strap, for example wrapped (e.g. entirely wrapped) by one or more other layers, e.g. soft outer layers. Consequently, the strap 3340 may possess the rigidity provided by the rigidiser but still be soft and comfortable to wear.4.3.3.4 Heating processes

[0276] In some forms of the technology, one or more straps 3340 comprised as part of a positioning and stabilising structure 3300 may be formed using one or more heating processes, including thermal lamination (which may be referred to as glue lamination) and thermoforming. The processes will now be explained with reference to Figs. 7A to 7C.

[0277] The various layers of the strap 3340 may be assembled together. For example, in the forms shown in Figs. 6A, 6B, 8 A to 8F, 9 and 10A to 10C, the patient-facing layer 3345, the first bonding layer 3344, the middle layer 3343, the second bonding layer 3342 and the non-patient-facing layer 3341 may be assembledtogether as a stack in the appropriate order. In other forms, the relevant layers of the strap 3340, as have previously been described, may be assembled together. The assembly of layers of strap 3340 may be placed in an oven 6010 as shown in Fig. 7A. The strap 3340 may be held in place within the oven 6010 by a frame 6020 or other type of securing mechanism. When in the oven 6010, the strap 3340 may be subject to sufficiently high temperatures and / or pressures for a sufficiently long time to cause the first bonding layer 3344 and, if present, the second bonding layer 3342 to be heat- activated and consequently bond to adjacent layers. For example the bonding layer(s) may melt, at least partially, and consequently seep into gaps formed in the adjacent layers. In some forms, for example where the bonding layers 3342 and 3344 are approximately 30-100 microns thick, the strap 3340 may be subject to temperatures of approximately 50-150°C for approximately 2-15 seconds. Once the strap 3340 is removed from the oven 6010 and permitted to cool, the bonding layers 3342 and 3344 may re-solidify and bond with adjacent layers of the strap 3340.

[0278] In some forms, the heating process may be applied to a plurality of straps 3340, or portions thereof, in order to join them together end-to-end (or side-to-side) in a seamless manner. For example, by applying multiple layers of material to a common bonding layer, the layers of material may be joined together by virtue of both being bonded to the same bonding layer. A positioning and stabilising structure 3300 comprised of straps 3340 joined in this manner may be free from seams. The resulting structure may improve comfort for the patient when wearing the positioning and stabilising structure 3300.

[0279] In some forms, the heating process may further comprise shaping the strap 3340, for example forming the strap 3340 into a non-planar shape. For example, a thermoforming process may be applied to the strap 3340. As shown in Fig. 7B, the strap 3340 may be presented to a die 6030 and punch 6035. The strap 3340 may be held in position relative to the die 6030 and punch 6035 by the frame 6020. The strap 3340 may be positioned between the die 6030 and the punch 6035. While the bonding layers 3342 and 3344 are still at a temperature in which they are able to be moulded, e.g. shortly after the strap 3340 is removed from the oven 6010 or while heat is still applied to the strap 3340, the punch 6035 is applied against the strap 3340, pushing it into the die 6030, as shown in Fig. 7C. By using a die and punch of the desired shape and size, the strap 3340 may be thermoformed into the desired shape. In some forms one or more binders 6037 may be applied to the strap 3340 during the thermoformingprocess. In some forms, a moulding step of the thermoforming process may involve applying a temperature in the range of approximately 100-200°C and a pressure in the range of approximately 2-5 bar for approximately 3-8 minutes, for example.

[0280] In some forms a process such as shown in Figs. 7A to 7C may be applied one or more times to a strap 3340 in order to arrive at the desired shape of the strap 3340. This may be useful when a strap 3340 is shaped into a complex shape, for example with curves in multiple directions.

[0281] As part of the thermoforming process, one or more surfaces of the strap 3340 may be debossed or embossed. For example, the die 6030 and / or punch 6035 may have shapes configured to impart surface shaping on the strap 3340.

[0282] The use of heat-activated materials, for example a thermoplastic or thermoset material, when compared to some conventional methods of forming a headgear strap, for example lamination using cut-to-shape processes, may be more energy and material efficient, e.g. reducing wastage of off-cuts from ultrasonic welding radio-frequency cutting or die cutting. The use of thermal lamination when compared to some conventional methods of forming a headgear strap, for example flame lamination, may allow for a lower density material, e.g. foam, to be used as a middle or inner layer, which may result in a softer and / or more breathable strap.4.3.3.5 Edge treatment

[0283] Earlier it has been described that, in some forms of the technology, for example as shown in Fig. 6B, the strap 3340 may comprise a thicker central region flanked by thinner edge regions. In certain forms, this configuration may be formed by pressing the edge regions to make them thinner than the central region. In some forms, the edge regions may be heat pressed to make them thinner than the central region. In some forms in which the strap 3340 is formed in this way, the middle layer 3343 may be formed from a material that deforms plastically when subject to sufficient pressures and / or sufficient pressures and temperatures. For example, the middle layer 3343 may be formed from a foam such as a polyurethane foam. The foam may be subject to a temperature in the range of approximately 50-150°C and pressed for 2 to 15 seconds, for example.

[0284] Another form of edge treatment for straps 3340 according to certain forms of the technology is to bind the edge or wrap the edge in an edge layer. This may be used in addition, or as an alternative, to the pressing process explained above. It maybe useful as an alternative to the fold-over configuration explained in relation to Figs. 8A to 8F, for example for straps 3340 having curved shapes in plan view where a fold-over may be difficult to do without creating crinkles. Edge binding may be useful for avoiding wear and tear on the strap 3340, which could cause the layers to separate, and may help prevent water penetration. It may also help present a smoother edge to the patient to increase comfort. An example of such edge binding is illustrated in Fig.9. Fig. 9 may illustrate some forms of the technology in which edge binding is applied to only one side of a strap 3340. Alternatively, Fig. 9 may illustrate one part of a strap 3340 according to some forms of the technology, i.e. one edge region of the strap, with the opposite edge region not being shown but being bound in a similar manner.

[0285] In such forms as shown in Fig. 9, the strap 3340 may comprise a strap body 3346. The strap body 3346 may be formed from a single layer or, in other forms, it may comprise a plurality of layers assembled into strap body 3346. For example, the strap body 3346 may comprise a plurality of layers described earlier in relation to Figs. 6A and 6B. The strap 3340 may further comprise one or more edge layers 3347, each edge layer 3347 being positioned along a respective edge region of the strap body 3346. The edge layer 3347 may be positioned such that it wraps around a lateral edge of the strap body 3346. This covers the lateral edge of the strap body 3346 so that any rough or sharp features do not come into contact with the patient’s skin during use, thus avoiding the discomfort that such features could cause. Such features may result from the way in which the edges of the strap body 3346, or its constituent layers, are cut or the way in which constituent layers of the strap body 3346 are joined.

[0286] To position each edge layer 3347 so that it wraps around an edge of the strap body 3346 as described, a first edge of the respective edge layer 3347 may be joined to a non-patient-facing side of the strap body 3346 and a second edge of each of the respective edge layer may be joined to a patient-facing side of the strap body 3347. To achieve this joining, adhesive may be used in some forms. In other forms, bonding layers 3342 and 3344 such as described earlier may be used.

[0287] In some forms, the strap 3340 may comprise one or more edges which comprises one or more edge layers 3347, as has been described. In some forms a rear portion 3310 of the strap 3340, for example one configured to overlie the patient’s occipital region in use, may be formed as a panel (e.g. a thick strap portion or an element in which the width does not differ significantly from the length) and the panelmay have edge layers 3347 provided to two, three or, in some forms, four sides of the panel. In forms in which the panel may be approximately circular or approximately oval, the edges along with the edge layers 3347 extend may partially or entirely surround the panel other than where straps extend away from the panel.4.3.3.6 Joining of headgear straps

[0288] A positioning and stabilising structure 3300 according to certain forms of the technology may be formed from two or more straps 3340 connected together to form a strap assembly. In some forms, each of the interconnected straps 3340 may have the same or a similar construction, e.g. arrangement of layers and edge structures such as those described earlier. In other forms, one strap 3340 having a first construction may be connected to another strap 3340 having a different construction. The different constructions of the straps may relate to the arrangement, number and types of layers and / or the structure of the edges of the straps, for example.

[0289] In certain forms of the technology, the side portions 3320 of the positioning and stabilising structure 3300 may be formed with one or more of the constructions described earlier with reference to Figs. 6A, 6B, 8 A to 8F, 9 and 10A to 10C, and in particular the constructions that provide these straps with relatively soft edges for patient comfort. In the use of a positioning and stabilising structure 3300 for a patient interface 3000, the side portions 3320 may particularly effect patient comfort since the side straps often come into contact with the patient’s face (e.g. cheek region) during use. In addition, some of these constructions may be easier to manufacture as a straight section of strap (at least in plan view) and the design of a positioning and stabilising structure 3300 may more readily allow for a side portion 3320 to be straight in plan view than straps in other parts of the positioning and stabilising structure 3300. In these forms, the other parts of the positioning and stabilising structure 3300 may comprise straps 3340 made from any other suitable construction.

[0290] In a positioning and stabilising structure 3300 comprising multiple straps 3340, the straps are joined at one or more joints. In some forms, two straps may be joined at a joint and the straps may be joined at an angle or substantially parallel (at least directly either side of the joint). In some forms, three or more straps may be jointed at a joint, and an example of a three-way strap joint is illustrated in Figs. 11A and 1 IB. In this form, a superior portion 3315, a rear portion 3310 and a side portion3320 are jointed together but this is by way of example only and in other forms, other strap portions may be joined together.

[0291] The plurality of straps 3340 that are joined together at a joint may be joined together by any suitable joining technique, and examples include welding, stitching and bonding (e.g. with adhesive). In the case of joining the straps by welding, the welding parameters may be determined by the construction of the straps 3340 and selected accordingly. Those of skill in the art may be able to determine appropriate welding parameters for a given construction of strap(s).

[0292] In the example of the form of technology illustrated in Figs. 11 A and 1 IB, Fig. 11 A may show the non-patient-facing side of the joint and 1 IB may show the patient-facing side of the joint. In this example, the strap portions may be joined such that a patient-facing side of the side portion 3320 is in face-to-face contact with a nonpatient facing side of the superior portion 3315 and the rear portion 3310. In another example, the joint may be arranged the opposite way around in use.

[0293] In certain forms, for example as shown in the illustrated example, the joint may be arranged such that the proximate ends of the superior portion 3315 and rear portion 3310 are separated by a small gap 3317, for example the gap 3317 may be significantly smaller in size than the width of each strap portion. In other forms, the joint may be arranged with no gap between these portions or a larger gap. Additionally, or alternatively, the proximate ends of the superior portion 3315 and rear portion 3310 may be formed with a cut-out or scalloped section along a part of the width of the proximate ends so that the proximate ends are separated by gap 3317 for part of their width, and gap 3318, that may be wider than gap 3317, along another part of their width. In the example shown, the wider gap 3318 may be on the side of the joint from which side portion 3320 extends outwardly. In certain forms, for example as illustrated, the proximate ends of the superior and rear portions may be formed so that gap 3318 tapers, for example from a wider width at the lateral edge of the superior and rear portions, to a narrow width where gap 3318 meets gap 3317.4.3.3.7 Pull tabs

[0294] The ends of straps 3340 of a positioning and stabilising structure 3300 may be provided with certain structures that may assist in manipulating the straps 3340 in use. For example, one or more pull tabs 3324 may be provided at each end of a strap 3340. Examples of pull tabs 3324 will now be described in relation to the sidestraps 3320 illustrated in Figs. 12A to 12D but it should be understood that in other forms similar pull tabs 3324 may be provided at the ends of other straps, including a rear strap comprised as part of a rear portion 3310 or a superior strap comprised as part of a superior portion 3315. A pull tab 3324 may make it easier for a user to grasp the strap, which may be useful to help the user don and / or remove the positioning and stabilising structure 3300. In some forms, a pull tab 3324 may be provided on the end of a strap 3340 that connects to another component by being threaded through a loop or opening on the other component and then being fastened in some way, e.g. to itself by a hook-and-loop mechanism. In these forms, a pull tab 3324 may facilitate a user passing the strap end through the loop, or grasping the strap end in order to disconnect the hook-and-loop connection.

[0295] A pull tab 3324 may comprised as part of an end region of a side strap 3320 and may be a layer or other body of material projecting outwardly from the end of the strap, typically in a longitudinal direction relative to the strap. The pull tab 3324 may have a thickness that is less than a thickness of the end region of the side strap 3320, which may make the pull tab 3324 easier for a user to grasp. In addition, or alternatively, the pull tab 3324 may be separated from the patient-facing side of the side strap 3320 by one or more layers of the strap, again making it easier for a user to grasp the pull tab 3324.

[0296] In some forms, the pull tab 3324 may be sandwiched between two or more layers of the side strap 3320 so that the pull tab 3324 projects outwardly from a middle region of the end of the strap. In other forms, for example as shown in Fig. 12D, the pull tab 3324 may be mounted to a non-patient-facing side of the side strap 3320.

[0297] As shown in Fig. 12D, the pull tab 3324 may comprise a projecting portion 3327, which projects outwardly from the end of the strap 3320 in plan view, and a non-projecting portion 3325, which in plan view does not. The projecting portion 3327 may be formed from a material, or have a surface, which is comfortable for the user to grip, for example it is free from hooks and bonding material, and may be formed from a material, or possess a texture, that facilitates the user gripping it. The non-projecting portion 3325 may be formed from a material that facilitates the joining of the pull tab 3324 to the main body of the side strap 3320, for example one side of the pull tab 3324 may be formed from hook-and-loop material to connect to a suitable surface on the main body of the side strap 3320. In other forms, the pull tab3324 may be bonded to the main body of the side strap 3320 using a suitable adhesive, or stitched.

[0298] In some forms, the pull tab 3324 may be formed to be more rigid than the rest of strap 3340, e.g. it may be formed from a material with a relatively high modulus of elasticity. This may be particularly useful where the pull tab 3324 is positioned at the end of a side portion 3320 of a positioning and stabilising structure 3300, since these portions may support some of the weight of the plenum chamber 3200 and / or seal-forming structure 3100.

[0299] In plan view the end corners of the pull tab 3324 may be rounded, as shown in Figs. 12A to 2D or bevelled. This may avoid the pull tab 3324 having angled corners which may be uncomfortable for the patient. In addition, or alternatively, the end corners 3326 of the main body of the side strap 3320 may be rounded, bevelled and / or tapered in order to reduce discomfort as may be caused by angled corners.4.3.4 Vent

[0300] In one form, the patient interface 3000 includes a vent 3400 constructed and arranged to allow for the washout of exhaled gases, e.g. carbon dioxide.

[0301] In certain forms the vent 3400 is configured to allow a continuous vent flow from an interior of the plenum chamber 3200 to ambient whilst the pressure within the plenum chamber is positive with respect to ambient. The vent 3400 is configured such that the vent flow rate has a magnitude sufficient to reduce rebreathing of exhaled CO2 by the patient while maintaining the therapeutic pressure in the plenum chamber in use.

[0302] One form of vent 3400 in 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.

[0303] The vent 3400 may be located in the plenum chamber 3200. Alternatively, the vent 3400 is located in a decoupling structure, e.g., a swivel.

[0304] In some forms, the patient interface 3000 may comprise a vent 3400 to allow a continuous flow of gases exhaled by the patient from an interior of the plenum chamber 3200 to ambient, for example throughout the patient’s entire respiratory cycle, said vent 3400 being sized and shaped to maintain the therapeutic pressure in the plenum chamber in use.4.3.5 Decoupling structure(s)

[0305] In one form the patient interface 3000 includes at least one decoupling structure, for example, a swivel or a ball and socket.4.3.6 Connection port

[0306] Connection port 3600 allows for connection to the air circuit 4170.4.3.7 Forehead support

[0307] In the form shown in Fig. 3A, the patient interface 3000 includes a forehead support 3700.4.3.8 Anti-asphyxia valve

[0308] In one form, the patient interface 3000 includes an anti-asphyxia valve.

[0309] Patient interfaces 3000 in accordance with the technology that are nose- and-mouth masks may each further comprise an anti-asphyxia valve (AAV). The AAV may be provided to the oral portion of the patient interface 3000. In some examples the AAV is integrated into the vent module 3410. The vent module 3410 may comprise a gas washout vent 3400 and an AAV. In some examples the AAV is provided in the chassis portion 3210 (or oral chassis portion 3217) of the patient interface 3000. In further examples the AAV is provided at a connection port 3600 of the patient interface 3000 or a connection between the plenum chamber 3200 and a short tube 3610, such as an inlet port connector.4.3.9 Ports

[0310] In one form of the present technology, a patient interface 3000 includes one or more ports that allow access to the volume within the plenum chamber 3200. 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 3200, such as the pressure.4.4 RPT DEVICE

[0311] An RPT device 4000 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, such as any of the methods, in wholeor in part, described herein. The RPT device 4000 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.

[0312] In one form, the RPT device 4000 is 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 cmH20, or at least 10cmH2O, or at least 20 cmH20.

[0313] The RPT device may have an external housing 4010, formed in two parts, an upper portion 4012 and a lower portion 4014. Furthermore, the external housing 4010 may include one or more panel(s) 4015. The RPT device 4000 comprises a chassis 4016 that supports one or more internal components of the RPT device 4000. The RPT device 4000 may include a handle 4018.

[0314] The pneumatic path of the RPT device 4000 may comprise one or more air path items, e.g., an inlet air filter 4112, an inlet muffler 4122, a pressure generator 4140 capable of supplying air at positive pressure (e.g., a blower 4142), an outlet muffler 4124 and one or more transducers 4270, such as pressure sensors and flow rate sensors.

[0315] One or more of the air path items may be located within a removable unitary structure which will be referred to as a pneumatic block 4020. The pneumatic block 4020 may be located within the external housing 4010. In one form a pneumatic block 4020 is supported by, or formed as part of the chassis 4016.

[0316] The RPT device 4000 may have an electrical power supply 4210, one or more input devices 4220, a central controller, a therapy device controller, a pressure generator 4140, one or more protection circuits, memory, transducers 4270, a data communication interface and one or more output devices. Electrical components 4200 may be mounted on a single Printed Circuit Board Assembly (PCBA) 4202. In an alternative form, the RPT device 4000 may include more than one PCBA 4202.4.5 AIR CIRCUIT

[0317] An air circuit 4170 in 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 device 4000 and the patient interface 3000.

[0318] In particular, the air circuit 4170 may be in fluid connection with the outlet of the pneumatic block 4020 and the patient interface. The air circuit may bereferred 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.4.6 HUMIDIFIER4.6.1 Humidifier overview

[0319] In one form of the present technology there is provided a humidifier 5000(e.g. as shown in Fig. 5A) to change the absolute humidity of air or gas for delivery to a patient relative to ambient air. Typically, the humidifier 5000 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.

[0320] The humidifier 5000 may comprise a humidifier reservoir 5110, a humidifier inlet 5002 to receive a flow of air, and a humidifier outlet 5004 to deliver a humidified flow of air. In some forms, as shown in Fig. 5A and Fig. 5B, an inlet and an outlet of the humidifier reservoir 5110 may be the humidifier inlet 5002 and the humidifier outlet 5004 respectively. The humidifier 5000 may further comprise a humidifier base 5006, which may be adapted to receive the humidifier reservoir 5110 and comprise a heating element 5240.4.7 GLOSSARY

[0321] 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.4.7.1 General

[0322] 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. oxygen enriched air.

[0323] 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.

[0324] 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.

[0325] In another example, ambient pressure may be the pressure immediately surrounding or external to the body.

[0326] 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.

[0327] 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.

[0328] 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.

[0329] 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’.

[0330] 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. Device flow rate, Qd, is the flow rate of air leaving the RPT device. Total flow rate, Qt, is the flow rate of air and any supplementary gas reaching the patient interface via the air circuit. Vent flow rate, Qv, is the flow rate of air leaving a vent to allow washout of exhaled gases. Leak flow rate, QI, 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.

[0331] 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.

[0332] 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.

[0333] 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.

[0334] 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.

[0335] 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.

[0336] 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.

[0337] Oxygen enriched air '. Air with a concentration of oxygen greater than that of atmospheric air (21%), for example at least about 50% oxygen, at least about 60% oxygen, at least about 70% oxygen, at least about 80% oxygen, at least about 90% oxygen, at least about 95% oxygen, at least about 98% oxygen, or at least about 99% oxygen. “Oxygen enriched air” is sometimes shortened to “oxygen”.

[0338] Medical Oxygen'. Medical oxygen is defined as oxygen enriched air with an oxygen concentration of 80% or greater.

[0339] Patient: A person, whether or not they are suffering from a respiratory condition.

[0340] Pressure'. Force per unit area. Pressure may be expressed in a range of units, including cmFFO, g-f / cm2and hectopascal. 1 cmFFO is equal to 1 g-f / cm2and is approximately 0.98 hectopascal (1 hectopascal = 100 Pa = 100 N / m2= 1 millibar ~0.001 atm). In this specification, unless otherwise stated, pressure is given in units of cmlLO.

[0341] 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.

[0342] Respiratory Pressure Therapy. 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.

[0343] Ventilator'. A mechanical device that provides pressure support to a patient to perform some or all of the work of breathing.4.7.1.1 Materials

[0344] 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.

[0345] Polycarbonate', a thermoplastic polymer of Bisphenol-A Carbonate.4.7.1.2 Mechanical properties

[0346] Resilience'. Ability of a material to absorb energy when deformed elastically and to release the energy upon unloading.

[0347] Resilient'. Will release substantially all of the energy when unloaded. Includes e.g. certain silicones, and thermoplastic elastomers.

[0348] 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.

[0349] 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.

[0350] 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.

[0351] 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 cmH20 pressure.

[0352] 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.4.7.2 Respiratory cycle

[0353] 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.

[0354] Expiratory portion of a breathing cycle: The period from the start of expiratory flow to the start of inspiratory flow.

[0355] 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 isdue to a reduction in breathing effort. In one form in adults, either of the following may be regarded as being hypopneas:(3272) 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.

[0356] Hyperpnec . An increase in flow to a level higher than normal.

[0357] 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.4.7.3 Anatomy4.7.3.1 Anatomy of the face

[0358] Ala: the external outer wall or “wing” of each nostril (plural: alar)

[0359] Alar angle:

[0360] Alare: The most lateral point on the nasal ala.

[0361] 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.

[0362] Auricle: The whole external visible part of the ear.

[0363] (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.

[0364] (nose) Cartilaginous framework: The cartilaginous framework of the nose comprises the septal, lateral, major and minor cartilages.

[0365] Columella: the strip of skin that separates the nares and which runs from the pronasale to the upper lip.

[0366] 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.

[0367] Frankfort horizontal plane: A line extending from the most inferior point of the orbital margin to the left tragion. The tragi on is the deepest point in the notch superior to the tragus of the auricle.

[0368] Glabella: Located on the soft tissue, the most prominent point in the midsagittal plane of the forehead.

[0369] 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.

[0370] 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.

[0371] 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.

[0372] Naso-labial sulcus or Naso-labial fold: The skin fold or groove that runs from each side of the nose to the comers of the mouth, separating the cheeks from the upper lip.

[0373] Naso-labial angle: The angle between the columella and the upper lip, while intersecting subnasale.

[0374] Otobasion inferior: The lowest point of attachment of the auricle to the skin of the face.

[0375] Otobasion superior: The highest point of attachment of the auricle to the skin of the face.

[0376] 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.

[0377] Philtrum: the midline groove that runs from lower border of the nasal septum to the top of the lip in the upper lip region.

[0378] Pogonion: Located on the soft tissue, the most anterior midpoint of the chin.

[0379] Ridge (nasal): The nasal ridge is the midline prominence of the nose, extending from the Sellion to the Pronasale.

[0380] 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.

[0381] Sellion: Located on the soft tissue, the most concave point overlying the area of the frontonasal suture.

[0382] Septal cartilage (nasal): The nasal septal cartilage forms part of the septum and divides the front part of the nasal cavity.

[0383] Subalare: The point at the lower margin of the alar base, where the alar base joins with the skin of the superior (upper) lip.

[0384] Subnasal point: Located on the soft tissue, the point at which the columella merges with the upper lip in the midsagittal plane.

[0385] Supramenton: The point of greatest concavity in the midline of the lower lip between labrale inferius and soft tissue pogonion4.7.3.1 Anatomy of the skull

[0386] Frontal bone: The frontal bone includes a large vertical portion, the squama frontalis, corresponding to the region known as the forehead.

[0387] Mandible: The mandible forms the lower jaw. The mental protuberance is the bony protuberance of the jaw that forms the chin.

[0388] 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.

[0389] 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.

[0390] 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.

[0391] 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.

[0392] Orbit: The bony cavity in the skull to contain the eyeball.

[0393] Parietal bones: The parietal bones are the bones that, when joined together, form the roof and sides of the cranium.

[0394] 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.

[0395] 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.4.7.3.3 Anatomy of the respiratory system

[0396] 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.

[0397] Larynx: The larynx, or voice box houses the vocal folds and connects the inferior part of the pharynx (hypopharynx) with the trachea.

[0398] 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.

[0399] 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.

[0400] 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).4.7.4 Patient interface

[0401] 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 CO2 rebreathing by a patient.

[0402] 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.

[0403] 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.

[0404] 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.

[0405] 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.

[0406] 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.

[0407] 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.

[0408] 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.

[0409] 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.

[0410] 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.

[0411] Swivel (noun): A subassembly of components configured to rotate about a common axis, preferably independently, preferably under low torque. In one form, theswivel 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.

[0412] Tie (noun): A structure designed to resist tension.

[0413] 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.4.8 OTHER REMARKS

[0414] A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in Patent Office patent files or records, but otherwise reserves all copyright rights whatsoever.

[0415] 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.

[0416] 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.

[0417] 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 towhich 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.

[0418] 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.

[0419] 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.

[0420] 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.

[0421] 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.

[0422] 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.

[0423] 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 beutilised 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.

[0424] 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.

Claims

5 CLAIMS1. A strap for a positioning and stabilising structure for a patient interface configured to deliver breathable gas at a therapeutic pressure of at least 4 cmlLO above ambient air pressure to an entrance to a patient’s airways, the strap comprising: a patient-facing layer configured to face towards a patient during use; a non-patient-facing layer configured to face away from the patient during use; a middle layer positioned between the patient-facing layer and the nonpatient-facing layer; a first bonding layer bonding the patient-facing layer and the middle layer together; and a second bonding layer bonding the non-patient-facing layer and the middle layer together.

2. A strap as claimed in claim 1, wherein a patient-facing side of the patientfacing layer has a different texture to a non-patient-facing side of the nonpatient-facing layer.

3. A strap as claimed in any one of claims 1 to 2, wherein the middle layer comprises a spacer fabric or foam.

4. A strap as claimed in any one of claims 1 to 3, wherein the first bonding layer comprises a first thermoplastic elastomer film.

5. A strap as claimed in any one of claims 1 to 4, wherein the second bonding layer comprises a second thermoplastic elastomer film.

6. A strap as claimed in claim 4 or 5, wherein the first thermoplastic elastomer film and / or the second thermoplastic elastomer film comprises perforations.

7. A strap as claimed in any one of claims 1 to 6, wherein the strap comprises a central region flanked by one or more edge regions, wherein the central region is thicker than the edge regions.

8. A strap as claimed in claim 7, wherein the middle layer is thicker in the central region than the edge regions.

9. A strap as claimed in any one of claims 7 to 8, wherein the strap further comprises one or more edge layers positioned along one of the edge regions, wherein a first edge of each of the edge layers is joined to a non-patient-facing side of the non-patient-facing layer and a second edge of each of the edge layers is joined to a patient-facing side of the patient-facing layer, wherein each edge layer wraps around a lateral edge of the respective edge region.

10. A strap for a positioning and stabilising structure for a patient interface configured to deliver breathable gas at a therapeutic pressure of at least 4 cmJLO above ambient air pressure to an entrance to a patient’s airways, the strap comprising: one or more layers assembled as a strap body; and one or more edge layers, each positioned along an edge region of the strap body, wherein a first edge of each of the edge layers is joined to a nonpatient-facing side of the strap body and a second edge of each of the edge layers is joined to a patient-facing side of the strap body, and wherein each edge layer wraps around a lateral edge of the respective edge region.

11. A strap for a positioning and stabilising structure for a patient interface configured to deliver breathable gas at a therapeutic pressure of at least 4 cmJLO above ambient air pressure to an entrance to a patient’s airways, the strap comprising: an inner layer; and an outer layer substantially or partially wrapped around the inner layer,wherein the inner layer and the outer layer are arranged to form a void between each lateral edge of the inner layer and an inner surface of the outer layer.

12. A strap as claimed in claim 11, wherein the outer layer comprises a central region and two edge regions flanking the central region, wherein the central region is positioned on a patient-facing side of the inner layer and the outer layer is wrapped around the inner layer so that the edge regions are on a nonpatient-facing side of the inner layer.

13. A strap as claimed in any one of claims 11 to 12, wherein the strap further comprises a non-patient-facing layer on a non-patient-facing side of the outer layer.

14. A strap as claimed in any one of claims 11 to 13, wherein the inner layer comprises a heat-activated material.

15. A strap as claimed in any one of claims 11 to 14, wherein the inner layer is a first inner layer and the outer layer is a first outer layer, and wherein the strap further comprises a second inner layer and a second outer layer substantially or partially wrapped around the second inner layer, wherein the second inner layer and the second outer layer are arranged to form a void between each lateral edge of the second inner layer and an inner surface of the second outer layer, and wherein a patient-facing side of the second outer layer is joined directly or indirectly to a non-patient-facing side of the first outer layer.

16. A strap as claimed in claim 15, wherein the second inner layer comprises a heat-activated material.

17. A strap as claimed in any one of claims 15 to 16, wherein the strap further comprises a bonding layer between the first outer layer and the second outer layer.

18. A strap as claimed in claim 17, wherein the bonding layer comprises a heat- activated material.

19. A strap as claimed in any one of claims 11 to 18, wherein the strap has substantially straight edges in plan view when the strap is laid flat.

20. A strap as claimed in any one of claims 11 to 18, wherein the strap has substantially curved edges in plan view.

21. A strap as claimed in any one of claims 11 to 20, wherein the strap comprises one or more darts and / or cut-outs in the substantially curved edges.

22. A positioning and stabilising structure for a patient interface configured to deliver breathable gas at a therapeutic pressure of at least 4 cmJLO above ambient air pressure to an entrance to a patient’s airways, the positioning and stabilising structure comprising one or more straps as claimed in any one of claims 1 to 21.

23. A positioning and stabilising structure as claimed in claim 22, wherein the one or more straps comprises a first strap and a second strap, wherein the first strap has a different stiffness from the second strap.

24. A positioning and stabilising structure as claimed in claim 23, wherein one or more of the bonding layers of the first strap has a different stiffness from the one or more bonding layers of the second strap.

25. A positioning and stabilising structure as claimed in claim 24, wherein the one or more bonding layers of the first strap comprises a different arrangement of gaps from the one or more bonding layers of the second strap.

26. A positioning and stabilising structure as claimed in any one of claims 22 to 25, wherein the one or more straps comprises a rear portion configured to overlie a posterior region of a patient’s head in use.

27. A positioning and stabilising structure as claimed in any one of claims 22 to26 when dependent on claim 7, wherein the rear portion comprises the thicker central region and the thinner edge regions.

28. A positioning and stabilising structure as claimed in any one of claims 22 to27 when dependent on claim 9 or claim 10, wherein the rear portion comprises the one or more edge layers.

29. A method of forming a strap for a positioning and stabilising structure for a patient interface, the method comprising: forming an assembly of: a patient-facing layer; a non-patient-facing layer; a middle layer positioned between the patient-facing layer and the non-patient-facing layer; a first bonding layer positioned between the patient-facing layer and the middle layer; and a second bonding layer positioned between the non-patientfacing layer and the middle layer, the method further comprising: heating the assembly to cause the first bonding layer to bond the patient-facing layer and the middle layer together and to cause the second bonding layer to bond the non-patient-facing layer and the middle layer together.

30. A method as claimed in claim 29, wherein the method further comprises thermoforming the strap into a non-planar shape.

31. A method as claimed in any one of claims 29 to 30, wherein the method further comprises pressing one or more edge regions of the strap to cause a central region of the strap flanked by the edge regions to be thicker than the edge regions.

32. A method as claimed in claim 31, wherein the step of pressing the one or more edge regions comprises heat pressing the one or more edge regions.

33. A method as claimed in any one of claims 20 to 32, wherein the method further comprises positioning one or more edge layers along one or more edge regions of the strap, wherein a first edge of each of the edge layers is joined to a non-patient-facing side of the non-patient-facing layer and a second edge of each of the edge layers is joined to a patient-facing side of the patient-facing layer, wherein each edge layer wraps around a lateral edge of the respective edge region.

34. A method of forming a strap for a positioning and stabilising structure for a patient interface, the method comprising: forming a plurality of layers into a strap body; and positioning one or more edge layers along respective edge regions of the strap body by joining a first edge of each of the edge layers to a nonpatient-facing side of the strap body and joining a second edge of each of the edge layers to a patient-facing side of the strap body, wherein each edge layer wraps around a lateral edge of the respective edge region.

35. A method of forming a strap for a positioning and stabilising structure for a patient interface, the method comprising substantially or partially wrapping an outer layer around an inner layer, wherein the inner layer and the outer layer are arranged to form a void between each lateral edge of the inner layer and an inner surface of the outer layer.

36. A method as claimed in claim 35, wherein the method further comprises positioning a central region of the outer layer on a patient-facing side of the inner layer and positioning edge regions of the outer layer that flank the central region on a non-patient-facing side of the inner layer.

37. A method as claimed in any one of claims 35 to 36, wherein the method further comprises positioning a non-patient-facing layer on a non-patientfacing side of the outer layer.

38. A strap for a positioning and stabilising structure for a patient interface configured to deliver breathable gas at a therapeutic pressure of at least 4 cmJLO above ambient air pressure to an entrance to a patient’s airways, the strap comprising a first layer, a second layer, and a bonding layer positioned between and bonding together the first and second layers, wherein there are gaps in the bonding layer.

39. A strap as claimed in 38, wherein the bonding layer comprises a thermoplastic elastomer film comprising perforations.

40. A strap as claimed in 38, wherein the bonding layer comprises an adhesive arranged in a repeating pattern.

41. A strap as claimed in 40, wherein the repeating pattern comprises any one or more of: dots; lines; and a net.

42. A positioning and stabilising structure for a patient interface configured to deliver breathable gas at a therapeutic pressure of at least 4 cmJLO above ambient air pressure to an entrance to a patient’s airways, the positioning and stabilising structure comprising one or more straps as claimed in any one of claims 38 to 41.

43. A positioning and stabilising structure for a patient interface configured to deliver breathable gas at a therapeutic pressure of at least 4 cmJLO above ambient air pressure to an entrance to a patient’s airways, the positioning and stabilising structure comprising a first strap and a second strap, wherein each of the first strap and the second strap comprises a first layer, a second layer, and a bonding layer positioned between and bonding together the first and second layers, wherein there are gaps in the bonding layer, and wherein the bonding layer of the first strap has gaps in a first arrangement and the bonding layer of the second strap has gaps in a secondarrangement, the first arrangement being different from the second arrangement.

44. A positioning and stabilising structure as claimed in claim 43, wherein the first and second arrangements form respective repeating patterns in the bonding layers.

45. A positioning and stabilising structure as claimed in 44, wherein the repeating patterns comprise any one or more of dots; lines; and a net.

46. A positioning and stabilising structure as claimed in any one of claims 43 to45, wherein a gap density of the first arrangement is different from a gap density of the second arrangement.

47. A positioning and stabilising structure as claimed in any one of claims 43 to46, wherein the positioning and stabilising structure is arranged such that the first strap is a portion selected from: a rear portion; a superior portion or a side portion of the positioning and stabilising structure, and the second strap is a different portion selected from the same list of portions.

48. A positioning and stabilising structure as claimed in any one of claims 43 to47, wherein at least one of the first and second straps comprises a third layer, wherein the bonding layer of each strap is a first bonding layer and each strap comprises a second bonding layer, positioned between and bonding together the second and third layers, wherein there are gaps in the second bonding layer.

49. A positioning and stabilising structure as claimed in any one of claims 43 to48, wherein an arrangement of gaps in the first bonding layer is the same as an arrangement of gaps in the second bonding layer.

50. A positioning and stabilising structure as claimed in any one of claims 43 to 48, wherein an arrangement of gaps in the first bonding layer is different from an arrangement of gaps in the second bonding layer.

51. A method of forming a positioning and stabilising structure for a patient interface, the method comprising: forming a first strap by bonding a first layer to a second layer using an intermediate bonding layer, wherein there are gaps in the bonding layer in a first arrangement; and forming a second strap by bonding a first layer to a second layer using an intermediate bonding layer, wherein there are gaps in the bonding layer in a second arrangement, wherein the first arrangement is different from the second arrangement.

52. A strap for a positioning and stabilising structure for a patient interface configured to deliver breathable gas at a therapeutic pressure of at least 4 cmlhO above ambient air pressure to an entrance to a patient’s airways, the strap comprising a layer comprising a central region flanked by first and second edge regions, the layer having a first side and a second side opposite the first side, the second sides of the first and second edge regions being bonded to the second side of the central region with two folded edges being formed between the central region and respective edge regions on respective lateral edges of the strap.

53. A strap as claimed in claim 52, wherein the strap further comprises an inner bonding layer substantially covering the second side of the first layer and bonding the second sides of the first and second edge regions to the second side of the central region.

54. A strap as claimed in claim 53, wherein the inner bonding layer comprises a thermoplastic elastomer film.

55. A strap as claimed in any one of claims 52 to 54, wherein the first and second edge regions are arranged such that edges of the first and second edge regions meet or are in close proximity over the second side of the central region.

56. A strap as claimed in any one of claims 52 to 55, wherein the strap further comprises a non-patient-facing layer bonded to the first side of the first and second edge regions, wherein the non-patient-facing layer spans across a gap or abutment between the first and second edge regions.

57. A positioning and stabilising structure for a patient interface configured to deliver breathable gas at a therapeutic pressure of at least 4 cmJLO above ambient air pressure to an entrance to a patient’s airways, the positioning and stabilising structure comprising one or more straps as claimed in any one of claims 52 to 56.

58. A method of forming a strap for a positioning and stabilising structure for a patient interface, wherein the strap comprises a layer comprising a central region flanked by first and second edge regions, the layer having a first side and a second side opposite the first side, wherein the method comprises: folding the layer to bring the second side of the first edge region into contact with the second side of the central region and forming a first folded edge on a first lateral edge of the strap; folding the layer to bring the second side of the first edge region into contact with the second side of the central region and forming a second folded edge on a second lateral edge of the strap; bonding the second side of the first edge region with the second side of the central region; and bonding the second side of the second edge region with the second side of the central region.

59. A method as claimed in claim 58, wherein the method further comprises bonding an inner bonding layer to the second side of the layer to substantially cover the second side of the layer prior to folding the layer.

60. A method as claimed in claim 58 or 59, wherein the method further comprises arranging the first and second edge regions such that edges of the first and second edge regions meet or are in close proximity over the second side of the central region.

61. A method as claimed in any one of claims 58 to 60, wherein the method further comprises bonding a non-patient-facing layer to the first side of the first and second edge regions to span across a gap or abutment between the first and second edge regions.

62. A patient interface comprising: a plenum chamber pressurisable to a therapeutic pressure of at least 4 cmJLO above ambient air pressure, said plenum chamber including a plenum chamber inlet port sized and structured to receive a flow of air at the therapeutic pressure for breathing by a patient; a seal-forming structure constructed and arranged to form a seal with a region of the patient’s face surrounding an entrance to the patient’s airways, said seal-forming structure having a hole therein such that the flow of air at said therapeutic pressure is delivered to at least an entrance to the patient’s nares, the seal-forming structure constructed and arranged to maintain said therapeutic pressure in the plenum chamber throughout the patient’s respiratory cycle in use; a vent to allow a continuous flow of gases exhaled by the patient from an interior of the plenum chamber to ambient, said vent being sized and shaped to maintain the therapeutic pressure in the plenum chamber in use; and a positioning and stabilising structure as claimed in any one of claims22 to 28 or 42 to 50 or 57.

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