Patient interface

Abstract

Forms of the technology relate to a patient interface for delivering breathable gas to a patient. The patient interface may comprise a pressurisable plenum chamber and a seal-forming structure to form a seal with a region of the patient's face surrounding an entrance to the patient's nares but not around the patient's mouth. A vent structure may allow a continuous flow of gases exhaled by the patient from an interior of the plenum chamber to ambient. The seal-forming structure may comprise at least one adhesive surface configured to adhere to a region of the patient's face to form the seal. An adhesive may be used to join the seal-forming structure to the plenum chamber. A shape retainer may help retain the shape of the seal-forming structure prior to adhering to the face. A release liner may cover the adhesive before joining and the liner may include one or more slits.

Description

PATIENT INTERFACE1 BACKGROUND OF THE TECHNOLOGY1.1 FIELD OF THE TECHNOLOGY[1] 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. The present technology relates to seal-forming structures for patient interfaces which form a seal with a patient’s airways through adhesive surfaces.1.2 DESCRIPTION OF THE RELATED ART1.2.1 Human Respiratory System and its Disorders[2] The respiratory system of the body facilitates gas exchange. The nose and mouth form the entrance to the airways of a patient.[3] 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.[4] A range of respiratory disorders exist. Certain disorders may be characterised by particular events, e.g. apneas, hypopneas, and hyperpneas.[5] 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.[6] A range of therapies have been used to treat or ameliorate such conditions. Furthermore, otherwise healthy individuals may take advantage of suchtherapies to prevent respiratory disorders from arising. However, these have a number of shortcomings.[7] One of the major issues in respiratory therapy is adherence, which is also referred to as compliance. Usually, a patient may be required to don a patient interface for prolonged periods as part of the respiratory therapy. Bulky and / or obtrusive patient interfaces often lead to patients discontinuing the respiratory therapy due to discomfort, inconvenience or interference with sleep. In particular, it is difficult to ensure that infants and children do not remove patient interface during respiratory therapy.1.2.2 Therapies[8] 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[9] 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).

[0010] 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.

[0011] Non-invasive ventilation (NIV) provides ventilatory support to a patient through the upper airways to assist the patient breathing and / or maintain adequate oxygen levels in the body by doing some or all of the work of breathing. The ventilatory support is provided via a non-invasive patient interface. NIV has been used to treat CSR and respiratory failure, in forms such as OHS, COPD, NMD andChest Wall disorders. In some forms, the comfort and effectiveness of these therapies may be improved.

[0012] Invasive ventilation (IV) provides ventilatory support to patients that are no longer able to effectively breathe themselves and may be provided using a tracheostomy tube or endotracheal tube. In some forms, the comfort and effectiveness of these therapies may be improved.1.2.3 Respiratory Therapy Systems

[0013] 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.

[0014] 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 / or data management.1.2.3.1 Patient Interface

[0015] 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 to the nose and / or mouth, a tube to the mouth or a tracheostomy tube to the trachea of a patient. Depending upon the therapy to be applied, the patient interface may form a seal, e.g., with a region of the patient's face, to facilitate the delivery of gas at a pressure at sufficient variance with ambient pressure to effect therapy, e.g., at a positive pressure of about 10 crnkhO relative to ambient pressure.

[0016] Conventionally, mask systems are used as patient interfaces to convey the flow of air. These mask systems typically include a plenum chamber which is secured against the patient’s face through headgear. The plenum chamber, with the patient’s face, encloses a volume of space, which may accommodate the facial features of the patient such as their nose and / or mouth. Often, the plenum chamber may be made of a rigid material. These aspects of the design of some conventional patient interfaces can make sleeping while wearing the patient interface on inconvenient, uncomfortable and potentially claustrophobic for the patient.

[0017] Mask systems other than those typically used for respiratory therapy may be functionally unsuitable for the present field. For example, purely ornamental masks may be unable to maintain a suitable pressure. Mask systems used forunderwater 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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), SCUBA masks, 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. As mentioned earlier, 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.

[0022] 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.

[0023] It is often recommended that a patient regularly wash their mask, if a mask is required to be cleaned, or if it is difficult to clean (e.g., difficult to assemble or disassemble), patients may not clean their mask and this may impact on patient compliance.

[0024] 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.

[0025] For these reasons, patient interfaces for delivery of CPAP during sleep form a distinct field.1.2.3.1.1 Seal-forming structure

[0026] Patient interfaces may include a seal-forming structure. Since it is in direct contact with the patient’s face, the shape and configuration of the seal-forming structure can have a direct impact the effectiveness and comfort of the patient interface.

[0027] 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 / or a nasal bridge region of a face. These different types of patient interfaces may be known by a variety of names by their manufacturer including nasal cushions, nasal pillows, and nasal puffs.

[0028] 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 single element that surrounds both nares and a mouth region in use. These patient interfaces may be referred in the art as oral cushions, oro-nasal cushions or full face cushions.

[0029] 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.

[0030] 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.

[0031] 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 isapplied 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 molded 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.

[0032] 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.

[0033] 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.

[0034] Another form of seal-forming structure may use adhesive to achieve a seal. A seal formed by an adhesive is usually highly effective with little or no leak for typical therapy pressures (e.g. up to 20 cmFLO).

[0035] Regular application and removal of an adhesive-based seal-forming structure may cause skin trauma or irritation. Moreover, conventional adhesive-based seal-forming structures require cleaning of the area of the skin to which the sealforming structure is to be adhered before affixing the seal-forming structure.Repeated cleaning, which may include alcohol swabbing, can cause damage to the skin.

[0036] Further, affixing an adhesive-based seal-forming structure in or around the nasal region may lead to weakening of adhesion due to moisture from the patient’s breath. In other regions of the face, the skin may also release moisture which can loosen adhesion, thereby causing leakages which can lead to ineffective respiratory therapy. In addition, when a patient is subjected to oxygen therapy, leakages can lead to unnecessary loss of the oxygen gas. This leakage of oxygen may be particularly disadvantageous in developed countries where medical oxygen is a scarce and expensive resource.

[0037] Adhesive-based seal-forming structures may also leave a residue, odour or colour on the patient’s skin, sometimes even after the seal-forming structure is removed.

[0038] Adhesive-based seal-forming structures may also crumple when placed in contact with the patient’s face because of differences between the contours of the patient’s face and the natural three-dimensional shape of the seal-forming structure. Crumples may provide regions where pressurised gas may leak, may result in facial marking or may be uncomfortable.

[0039] Adhesive-based seal-forming structures may be difficult to apply to the patient’s face. For example, a thin seal-forming structure may not hold its shape well and may therefore easily fold or adhere to an intended surface.

[0040] A range of patient interface seal-forming structure technologies are disclosed in the following patent applications, assigned to ResMed Pty Ltd: WO 1998 / 004,310; WO 2006 / 074,513; WO 2010 / 135,785. Examples of patient interfaces including seal-forming structures which use an adhesive to achieve a seal are disclosed in PCT Publication No. WO 2023 / 015340, the contents of which are herein incorporated by reference.

[0041] 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 Puritan-Bennett Corporation.

[0042] ResMed Limited has manufactured the following products that incorporate nasal pillows: SWIFT™ nasal pillows mask, SWIFT™ II nasal pillows mask, SWIFT™ LT nasal pillows mask, SWIFT™ FX nasal pillows mask and MIRAGE LIBERTY™ full-face mask. The following patent applications, assigned to ResMed Limited, describe examples of nasal pillows masks: International Patent Application W02004 / 073,778 (describing amongst other things aspects of the ResMed Limited SWIFT™ nasal pillows), US Patent Application 2009 / 0044808 (describing amongst other things aspects of the ResMed Limited SWIFT™ 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 LIBERTY™ full-face mask); International Patent Application WO 2009 / 052,560 (describing amongst other things aspects of the ResMed Limited SWIFT™ FX nasal pillows).1.2.3.1.2 Positioning and stabilising

[0043] 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.

[0044] One technique is the use of adhesives. Examples of patient interfaces which use an adhesive to position and stabilise a seal-forming structure with the face are disclosed in PCT Publication No. WO 2023 / 015340, the contents of which are herein incorporated by reference. One advantage of the use of adhesives to position and stabilise the seal-forming structure on the patient’s face is that it avoids the need for headgear (discussed below), which can be uncomfortable, claustrophobic and adds manufacturing cost and complexity. However, as mentioned before, the use of adhesives, as is known in the art, has some disadvantages.

[0045] Another technique is the use of one or more straps and / or stabilising harnesses. Many such harnesses suffer from being one or more of ill-fitting, bulky, uncomfortable and awkward to use. They tend to be less air-tight than adhesivebased seal forming structures. Moreover, straps and / or stabilising harnesses tend to leave markings on the face when used overnight.1.2.3.1.3 Pressurised Air Conduit

[0046] 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.

[0047] 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

[0048] 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 devicesmay also act as flow therapy devices. Examples of RPT devices include a CPAP device and a ventilator.1.2.3.3 Air circuit

[0049] 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

[0050] 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

[0051] 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

[0052] 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.

[0053] A first aspect of the present technology relates to apparatus 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 one form of the present technology is a patient interface comprising a seal-forming structure which is configured to form a seal with a region of the patient’s face surrounding an entrance to the patient’s airways.

[0056] Another aspect of one form of the present technology is a patient interface comprising a seal-forming structure having an opening such that a flow of breathable gas is delivered to at least an entrance to the patient’s nares.

[0057] Another aspect of one form of the present technology is a patient interface comprising a seal-forming structure which further comprises at least one adhesive surface configured in use to adhere to the region of the patient’s face surrounding the entrance to the patient’s airways to form the seal.

[0058] An aspect of one form of the present technology is a patient interface comprising a plenum chamber pressurisable to a therapeutic pressure of at least 6 cmtkO above ambient air pressure, said plenum chamber including a plenum chamber inlet port configured to receive a flow of breathable gas at the therapeutic pressure for breathing by the patient.

[0059] In one form of the present technology, the seal-forming structure is configured to maintain said therapeutic pressure in the plenum chamber throughout the patient’s respiratory cycle in use.

[0060] Another aspect of one form of the present technology is a patient interface that has a perimeter shape which is complementary to that of an intended wearer. In one form, the seal-forming structure is configured to have a perimeter shape which is complementary to the region of the patient’s face surrounding the entrance to the patient’s airways to form the seal. The regions to which the sealforming structure is to be adhered to may be referred to as the target sealing regions. In one form, the seal-forming structure is configured such that the region of the patient’s face comprises regions of the patient’s face adjacent to, or surrounding, the nares.

[0061] According to one aspect of the technology there is provided a patient interface for use in delivering breathable gas to a patient. The patient interface may comprise a seal-forming structure may be configured 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 comprise at least one adhesive surface configured in use to adhere to a region of the patient’s face to form the seal. The seal-forming structure may be configured with one or more notches formed in an edge of a lateral region of the seal-forming structure.

[0062] According to one aspect of the technology there is provided a patient interface for use in delivering breathable gas to a patient. The patient interface may comprise a plenum chamber pressurisable to a therapeutic pressure of at least 6 cmfTO above ambient air pressure. The plenum chamber may include a plenum chamber inlet port configured to receive a flow of breathable gas at the therapeutic pressure for breathing by the patient. The patient interface may further comprise a seal-forming structure provided to the plenum chamber. The seal-forming structure may be configured 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 an opening therein such that the flow of breathable gas is delivered to at least an entrance to the patient’s nares. The seal-forming structure may be configured 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 structure to allow a continuous flow of gases exhaled by the patient from an interior of the plenum chamber to ambient. The vent structure being configured to maintain the therapeutic pressure in the plenum chamber in use. The seal-forming structure may comprise at least one adhesive surface configured in use to adhere to a region of the patient’s face to form the seal. The seal-forming structure may be configured with one or more notches formed in an edge of a lateral region of the seal-forming structure.

[0063] In certain forms, at least one of the one or more notches may be formed in a region of the seal-forming structure that is configured to adhere to the patient’s nose in use.

[0064] In certain forms, at least one of the one or more notches may be formed in a region of the seal-forming structure that is configured to adhere to a nasal ala of the patient in use.

[0065] In certain forms, at least one of the one or more notches may be formed in a region of the seal-forming structure that is configured to adhere to the patient’s cheek in use.

[0066] In certain forms, at least one of the one or more notches may be formed between adjacent regions of the seal-forming structure that are respectively configured to adhere to the patient’s face either side of a junction between the patient’s nasal ala and the patient’s cheek in use.

[0067] In certain forms, at least one of the one or more notches may be formed in a region of the seal-forming structure that is configured to adhere to the patient’s lip superior region in use.

[0068] In certain forms, at least one of the one or more notches may be formed in a region of the seal-forming structure that is configured to adhere to a patient’s nasolabial sulcus region in use.

[0069] In certain forms, the seal-forming structure may be configured so that at least one of the one or more notches extends in use substantially laterally inwardly towards the patient’s medial plane from a lateral edge of the seal-forming structure.

[0070] In certain forms, at least one of the one or more notches may be substantially slit-shaped.

[0071] In certain forms, the one or more notches may comprise a first notch and a second notch. The first notch may be formed in a region of the seal-forming structure that is configured to be located on one side of the medial plane during use. The second notch may be formed in a region of the seal-forming structure that is configured to be located on the other side of the medial plane during use.

[0072] According to one aspect of the technology there is provided a patient interface for use in delivering breathable gas to a patient. The patient interface may comprise a plenum chamber pressurisable to a therapeutic pressure of at least 6 cmfTC) above ambient air pressure. The plenum chamber may include a plenum chamber inlet port configured to receive a flow of breathable gas at the therapeutic pressure for breathing by the patient. The patient interface may further comprise a seal-forming structure provided to the plenum chamber. The seal-forming structure may be configured 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 an opening therein such that the flow of breathable gas is delivered to at least an entrance to the patient’s nares. The seal-forming structure may be configured 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 structure to allow a continuous flow of gases exhaled by the patient from an interior of the plenum chamber to ambient. The vent structure may be configured to maintain the therapeutic pressure in the plenum chamber in use. The seal-forming structure may comprise at least one adhesive surface configured in use to adhere to a region of the patient’s face to form the seal. The seal-forming structure may be configured with one or more notches formed in an edge of the seal-forming structure which is positioned substantially inferior to the opening during use.

[0073] In certain forms, at least one of the one or more notches may be formed in a region of the seal-forming structure that is configured to adhere to the patient’s subnasale in use.

[0074] In certain forms, at least one of the one or more notches may be formed in a region of the seal-forming structure that is configured to adhere to the patient’s lip superior region.

[0075] In certain forms, at least one of the one or more notches may be formed in a region of the seal-forming structure that is configured to adhere to a region of the patient’s face positioned on or proximate the medial plane in use.

[0076] In certain forms, at least one of the one or more notches may be formed in a region of the seal-forming structure that is configured to adhere to a region of the patient’s face positioned lateral to the medial plane in use.

[0077] According to one aspect of the technology there is provided a patient interface for use in delivering breathable gas to a patient. The patient interface may comprise a plenum chamber pressurisable to a therapeutic pressure of at least 6 cmtkO above ambient air pressure. The plenum chamber may include a plenum chamber inlet port configured to receive a flow of breathable gas at the therapeutic pressure for breathing by the patient. The patient interface may further comprise a seal-forming structure configured 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 an opening therein such that the flow of breathable gas is delivered to at least an entrance to the patient’s nares. The seal-forming structure may be configured to maintain said therapeutic pressure in the plenum chamber throughout the patient’s respiratory cycle in use. The seal-forming structure may comprise at least one adhesive surface configured in use to adhere to a region of the patient’s face to form the seal. The patient interface may further comprise a connecting portion positioned between the seal-forming structure and the plenum chamber. The connecting portion may be formed with a thickness that is substantially thinner than adjacent regions of the plenum chamber and the seal-forming structure to allow relative displacement between the seal-forming structure and the plenum chamber. The patient interface may further comprise a vent structure to allow a continuous flow of gases exhaled by the patient from an interior of the plenum chamber to ambient. The vent structure may be configured to maintain the therapeutic pressure in the plenum chamber in use.

[0078] In certain forms, the connecting portion may extend around an opening formed in a patient-facing side of the plenum chamber.

[0079] According to one aspect of the technology there is provided a patient interface for use in delivering breathable gas to a patient. The patient interface may comprise a plenum chamber pressurisable to a therapeutic pressure of at least 6 cmfTO above ambient air pressure. The plenum chamber may include a plenum chamber inlet port configured to receive a flow of breathable gas at the therapeutic pressure for breathing by the patient. The patient interface may further comprise a seal-forming structure provided to the plenum chamber. The seal-forming structure may be configured 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 an opening therein such that the flow of breathable gas is delivered to at least an entrance to the patient’s nares. The seal-forming structure may be configured to maintain said therapeutic pressure in the plenum chamber throughout the patient’s respiratory cycle in use. The seal-forming structure may comprise at least one adhesive surface configured in use to adhere to a region of the patient’s face to form the seal. The patient interface may further comprise a vent structure to allow a continuous flow of gases exhaled by the patient from an interior of the plenum chamber to ambient. The vent structure may be configured to maintain the therapeutic pressure in the plenum chamber in use. The patient interface may further comprise at least one shape retainer removably mounted to the seal-forming structure and configured to promote retention of the shape of the seal-forming structure before the seal-forming structure is made to adhere to the patient’s face. The at least one shape retainer may comprise a loop which extends around at least a substantial part of an outer perimeter of the seal-forming structure.

[0080] In certain forms, the at least one shape retainer may be removably mounted to a non-patient-facing side of the seal-forming structure.

[0081] In certain forms, the at least one shape retainer may comprise a radially inner edge and the at least one shape retainer may be configured such that, when the at least one shape retainer is mounted to the seal-forming structure, the radially inner edge is spaced from the opening.

[0082] In certain forms, the at least one shape retainer may comprise a first end and a second end separated by a gap.

[0083] In certain forms, the at least one shape retainer may comprise a tab configured to be grasped by a user for removing the at least one shape retainer from the seal-forming structure.

[0084] In certain forms, the tab may extend radially inwards from the loop towards the opening.

[0085] In certain forms, the tab may extend from an outer lateral region of the loop in a lateral-medial direction.

[0086] In certain forms, the tab may be a first tab and the at least one shape retainer may comprise a second tab configured to be grasped by a user for removing the at least one shape retainer from the seal-forming structure. The first tab may be located on one side of the patient’s medial plane in use. The second tab may be located on the other side of the patient’s medial plane in use.

[0087] According to one aspect of the technology there is provided a patient interface for use in delivering breathable gas to a patient. The patient interface may comprise a plenum chamber pressurisable to a therapeutic pressure of at least 6 cmtkO above ambient air pressure. The plenum chamber may include a plenum chamber inlet port configured to receive a flow of breathable gas at the therapeutic pressure for breathing by the patient. The patient interface may further comprise a seal-forming structure. The seal-forming structure may be configured 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 an opening therein such that the flow of breathable gas is delivered to at least an entrance to the patient’s nares. The sealforming structure may be configured 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 structure to allow a continuous flow of gases exhaled by the patient from an interior of the plenum chamber to ambient. The vent structure may be configured to maintain the therapeutic pressure in the plenum chamber in use. The seal-forming structure may comprise at least one patient-facing adhesive surface configured in use to adhere to a region of the patient’s face to form the seal. The seal-forming structure may further comprise at least one non-patient- facing adhesive surface formed around the opening and configured to adhere to a patient-facing side of the plenum chamber. The seal-forming structure may further comprise a non-patient-facing removable layer positioned over the non-patient- facing adhesive surface and configured to be removed prior to adhering the plenumchamber to the seal-forming structure. In the non-patient-facing removable layer may be formed a slit extending from an edge of the non-patient-facing removable layer.

[0088] In certain forms, the seal-forming structure may further comprise a patient-facing removable layer positioned over the patient-facing adhesive surface and configured to be removed prior to adhering the seal-forming structure to the patient’s face.

[0089] In certain forms, the non-patient-facing removable layer may be formed with a hole therein. The hole may substantially align with the opening when the non- patient-facing removable layer is positioned over the non-patient-facing adhesive surface.

[0090] In certain forms, the slit may extend from a radially outer edge of the non-patient-facing removable layer to a radially inner edge of the non-patient-facing removable layer.

[0091] In certain forms, the slit may extend at least partially in an azimuthal direction around the non-patient-facing removable layer.

[0092] In certain forms, the non-patient-facing removable layer may comprise a tab configured to be grasped by a user for removing the non-patient-facing removable layer from the seal-forming structure.

[0093] In certain forms, the tab may extend outwardly from an edge of the non- patient-facing removable layer substantially opposite the slit.

[0094] In certain forms, the slit may be a first slit and in the non-patient-facing removable layer may be formed a second slit extending from an edge of the non- patient-facing removable layer. The second slit may extend from a radially outer edge of the non-patient-facing removable layer to a radially inner edge of the non- patient-facing removable layer.

[0095] 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.

[0096] 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.

[0097] 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

[0098] 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:

[0099] Fig. 1 shows a system including a patient 1000 wearing a patient interface 3000, receiving a supply of air at positive pressure from an RPT device 4000. The patient is sleeping lying on their side.

[0100] Fig. 2A 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] Fig. 2G shows a side view of the superficial features of a nose.

[0107] Fig. 2H shows subcutaneal structures of the nose, including lateral cartilage, septum cartilage, greater alar cartilage, lesser alar cartilage, sesamoidcartilage, nasal bone, epidermis, adipose tissue, frontal process of the maxilla and fibrofatty tissue.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] Fig. 2L shows an anterolateral view of a nose.

[0112] Fig. 3 shows a patient interface which is configured to adhere to an alar rim region of a patient’s face in accordance with one form of the present technology.

[0113] Fig. 4A shows a perspective view of a patient interface which is adhered to a patient’s face in accordance with one form of the present technology.

[0114] Fig. 4B shows a side view of the patient interface of Fig. 4A.

[0115] Fig. 5 a perspective view of a patient interface which is adhered to an alar crease region of a patient’s face in accordance with one form of the present technology.

[0116] Fig. 6 shows a seal-forming structure in accordance with one form of the present technology.

[0117] Fig. 7 is a perspective view illustration of a patient interface in accordance with another form of the present technology.

[0118] Fig. 8 illustrates a perspective view of a patient interface according to one form of the technology.

[0119] Fig. 9 is a perspective view illustration of a patient interface according to another form of the technology.

[0120] Fig. 10 is a front view illustration of the patient interface shown in Fig. 9.

[0121] Fig. 11 is an illustration of the patient interface shown in Fig. 9 when worn by a patient.

[0122] Fig. 12 is a front view illustration of a patient interface according to another form of the technology.

[0123] Fig. 13 is a perspective view illustration of the patient interface shown in Fig. 20 with another component.

[0124] Fig. 14A is an exploded view illustration of the patient interface shown in Fig. 20.

[0125] Fig. 14B is an exploded view illustration of a patient interface prior to assembly according to another form of the technology.

[0126] Fig. 15 is an exploded view illustration of a patient interface according to another form of the technology.

[0127] Fig. 16 is a perspective view illustration of the patient interface shown in Fig. 15 when worn by a patient.

[0128] Fig. 17 shows part of the patient interface shown in Fig. 15 when assembled (top part of figure) and in an exploded view (bottom part of figure).

[0129] Fig. 18A is a perspective view illustration of a patient interface according to another form of the technology.

[0130] Fig. 18B is a plan view illustration of a shape retainer according to a form of the technology.

[0131] Fig. 19 is an exploded view illustration of a patient interface prior to assembly according to another form of the technology.

[0132] Figs. 20A to 201 are plan view illustrations of non-patient-facing removable layers according to certain forms of the technology.

[0133] Fig. 21A is a perspective view illustration of part of a patient interface prior to assembly according to another form of the technology.

[0134] Fig. 21B is an exploded view illustration of the part of the patient interface shown in Fig. 21 A.

[0135] Fig. 22A is a perspective view illustration of part of a patient interface prior to assembly according to another form of the technology.

[0136] Fig. 22B is an exploded view illustration of the part of the patient interface shown in Fig. 22A.4 DETAILED DESCRIPTION OF EXAMPLES OF THETECHNOLOGY

[0137] Before the present technology is described in further detail, it is to be understood that the technology is not limited to the particular examples described herein, which may vary. It is also to be understood that the terminology used in thisdisclosure is for the purpose of describing only the particular examples discussed herein, and is not intended to be limiting.

[0138] 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

[0139] 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.

[0140] 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.

[0141] In certain examples of the present technology, mouth breathing is limited, restricted or prevented.4.2 RESPIRATORY THERAPY SYSTEMS

[0142] In certain forms, as shown in Fig. 1, the present technology comprises a respiratory therapy system 2000 for treating a respiratory disorder. The respiratory therapy system 2000 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.

[0143] In the form of the technology shown in Fig. 1, the RPT device 4000 is portable and can be carried by the patient 1000, for example attached to the patient’s clothing. In alternative forms of the present technology (not shown in the Figs.), the RPT device is configured to rest on a nearby surface during use, for example a bedside table.

[0144] Further, the respiratory therapy system 2000 may include a humidifier to change the absolute humidity of air or gas for delivery to a patient relative to ambient air. Typically, the humidifier 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.4.3 PATIENT INTERFACE

[0145] Figs. 3-6 and 8-13 show forms of the technology providing a patient interface 3000 (or parts thereof) in which the patient interface 3000 does not extend into the nares of the patient 1000. In the form of technology shown in Fig. 7, patient interface 3000 comprises nasal prongs 3250 that engage with and / or extend into the nares. These types of patient interfaces will be described in more detail in the following paragraphs.

[0146] A patient interface 3000, such as shown in Figs. 3 to 13, in accordance with certain aspects of the present technology comprises at least some of the following functional aspects: a seal-forming structure 3100, a plenum chamber 3200, a positioning and stabilising structure 3300 and a vent 3400.

[0147] In some forms a functional aspect may be provided by one or more physical components. In some forms, one physical component may provide one or more functional aspects. In use the seal-forming structure 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.

[0148] The seal-forming structure 3100 and / or the plenum chamber 3200 may be formed of one or more modular components in the sense that it or they can be replaced with different components, for example components of a different size and / or shape.

[0149] 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.

[0150] 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 cmFEO with respect to ambient.4.3.1 Seal-forming structure

[0151] In one form of the present technology, the patient interface 3000 includes a seal-forming structure 3100 which is configured to form a seal with a region of the patient’s face. The seal-forming structure 3100 is thereby configured to secure the plenum chamber 3200 in a sealing engagement with respect to the patient’s face. Theseal-forming structure 3100 may form an opening to allow a flow of breathable gas to be delivered to at least an entrance to the patient’s nares.

[0152] In one form of the present technology, the seal-forming structure 3100 provides a target seal-forming region. 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, and the shape of a patient’s face.

[0153] In certain forms of the present technology, the seal-forming structure 3100 is configured so that the shape of the target seal-forming region substantially matches or resembles the shape of the region of the patient’s face to which the sealforming structure 3100 is in use attached, and / or is constructed to be sufficiently flexible that it is able to deform to do so. This may promote a greater degree of sealing against the patient’s face and, in the case of a seal-forming structure that adheres to the patient’s face, avoids the adhesive surface 3102 pulling on the underlying skin when the patient interface 3000 is in use.

[0154] In certain forms of the present technology, the seal-forming structure 3100 is constructed from a biocompatible material, e.g. silicone rubber.

[0155] A seal-forming structure 3100 in accordance with the present technology may be constructed from a soft, flexible, resilient material such as silicone, a thermoplastic elastomer (TPE), or plastic such as polyurethane.

[0156] 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.

[0157] More details of seal-forming structure according to certain forms of the technology are described below. Other aspects of seal-forming structures according to forms of the technology are described in more detail in PCT Publication No. WO 2023 / 015340, the contents of which are herein incorporated by reference.4.3.1.1 Sealing mechanisms4.3.1.1.1 Adhesive

[0158] The seal-forming structure 3100 of certain forms of the technology is configured to adhere, through an adhesive provided on an adhesive surface 3102 of the seal-forming structure 3100, to one or more regions of the patient’s face so as to form a seal with a region of the patient’s face surrounding an entrance to one or more of the patient’s airways. For example, the seal-forming structures 3100 in Figs. 3 to 8, 9 to 18A, 19, 21 and 22 are each configured to seal around the nasal airways of the patient 1000.

[0159] The adhesive-based attachment of the seal-forming structure 3100 to the patient’s face allows formation of a highly airtight seal. A high quality seal improves the effectiveness of positive pressure respiratory therapy since the desired pressure can be maintained in the patient interface. Furthermore, a high quality seal reduces the overall power required to be expended by an RPT device 4000 to maintain the pressure of the breathable gas in the patient interface 3000. When the seal-forming structure 3100 is adhered to the patient’s face, another positioning and stabilising structure, e.g. headgear, may not be provided.4.3.1.2 Sealing Region of Patient’s Face

[0160] In certain forms of the technology, the seal-forming structure 3100 forms a seal in use with a region of the patient’s face surrounding an entrance of the patient’s nares. In certain forms, the seal-forming structure 3100 forms a seal around an entrance to the patient’s nasal airways (i.e. one or both nares) but not around the patient’s mouth.

[0161] In the exemplary forms of technology shown in Figs. 5, 9-18A, 19 and 21-22, 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.

[0162] 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 aseal 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. This patient interface 3000 may deliver a supply of air or breathable gas to both nares of patient 1000 through a single orifice.

[0163] 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 certain forms, for example as shown in Figs. 3-18A, 19 and 21-22, the seal-forming structure 3100 is configured to form a seal in use with inferior surfaces of the nose around the nares. The seal-forming 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 seal-forming structure 3100 may seal to the patient’s lip superior. The shape of the seal-forming structure 3100 may be configured to match or closely follow the underside of the patient’s nose and, in some forms, 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.

[0164] In the form shown in Fig. 7, 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. 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 nasalpillow is connected. For example, the frusto-cone may be axially displaced towards the structure to which the stalk is connected.

[0165] A more detailed description of regions of the patient’s face to which a seal-forming structure 3100 seals during use will now be described in the case of certain forms of the technology in which the seal-forming structure is configured to adhere to the patient’s face during use.

[0166] In the form of the technology shown in Fig. 3, the seal-forming structure 3100 is configured to adhere to regions of the patient’s face immediately surrounding the nares. These regions may comprise (see Fig. 2F): the alar rim region 3141 (i.e. regions of the ala that are immediately adjacent the nares and may be generally inferiorly facing); the superior-most region of the lip superior 3142, which may comprise the subnasale and / or the region immediately inferior of the subnasale; and an anterior region of the nose that is inferior, e.g. immediately inferior, to the pronasale 3143. In the lateral direction, the seal-forming structure 3100 extends to a region 3144 slightly inferior to the alar crest point, for example a region immediately medial to the junction between the alar crest point and the nasolabial sulcus. In the form of the technology shown, the seal-forming structure 3100 does not adhere to a significant part of the side regions of the nasal alar, although in some forms, or for some faces, it may adhere to the inferior regions of the side regions of the nasal alar. Furthermore, the seal-forming structure 3100 of Fig. 3 does not adhere to the pronasale.

[0167] In the form of the technology shown in Fig. 3, the region of the patient’s face to which the seal-forming structure 3100 adheres is a band entirely surrounding both the patient’s nares. The band may be approximately constant in width around the perimeter of the band.

[0168] The region of the face covered by the seal-forming structure 3100 in the form of the technology shown in Fig. 3 has been found not to change shape substantially when a patient 1000 changes their position because this facial region predominantly comprises of cartilage and bone and has relatively little adipose tissue, as compared to the cheek or chin areas. This facial region is also typically free of facial hair or has very little facial hair (for example, some facial hair may be present on the superior-most region of the lip superior 3142). A seal-forming structure 3100 that adheres to this region may be particularly advantageous for a patient 1000 with upper lip hair.

[0169] The region of the face covered by the seal-forming structure 3100 in the form of the technology shown in Fig. 3 has also been found to have relatively little variation in shape across patients in representative population samples, including patients of a variety of races.

[0170] Further, the size of this region (which may be referred to as the alar rim region) is small in size since it immediately surrounds the nares.

[0171] In another exemplary form, as shown in Figs. 4 A and 4B, the sealforming structure 3100 is configured to adhere to a facial region that extends more superiorly compared to the region shown in Fig. 3 and includes the side regions of the nasal alar. In some forms, the seal-forming structure 3100 is configured to adhere to a side region of the nasal alar and may also extend radially outwardly sufficiently far to adhere in use to regions of the cheeks adjacent the nasal alar crest point, e.g. the regions between the nasal alar and the nasolabial sulcus. This seal-forming structure 3100 may also adhere to the regions of the face to which the seal-forming structure of Fig. 3 adheres. The larger area of adhesion of the seal-forming structure in Figs. 4A and 4B may improve the amount of adhesion and result in fewer leaks compared to the seal-forming structure of Fig. 3, but may result in more discomfort for the patient.

[0172] In another exemplary form, as shown in Fig. 5, the seal-forming structure 3100 is configured to adhere to a larger region of the patient’s face than the region to which the seal-forming structures of Figs. 3, 4A and 4B adhere. In this form the sealforming structure adheres to a region that extends in a superior direction up to the alar crease region, i.e. when the seal-forming structure is adhered to the patient’s face, a superior- most portion of the seal-forming structure adheres to the patient’s alar crease. The seal-forming structure 3100 in this form may additionally, or alternatively, adhere to a substantial portion of the lip superior. Furthermore, the seal-forming structure 3100 in this form may additionally, or alternatively, adhere to the pronasale region, which may include a point which is immediately superior to the pronasale. In the lateral direction, the seal-forming structure 3100 in this form adheres to a region of the patient’s cheeks adjacent to the nasal alar, including the regions between the nasal alar and the nasolabial sulcus, and the seal-forming structure 3100 may cover the nasal alar completely in use. This seal-forming structure 3100 may also adhere to the regions of the face to which the seal-forming structures of Figs. 3, 4A and / or 4B adhere. Alternatively, the seal-forming structure of Fig. 5 may be configured to adhere to some regions positioned radially outwardlyfrom the nares compared to some regions to which the seal-forming structures of Figs. 3, 4 A and / or 4B adhere.

[0173] In certain forms of the technology, for example the form of the technology shown in Fig. 6, the seal-forming structure 3100 may be configured to adhere to the columella. For example, the seal-forming structure 3100 may comprise a septum region 3132 extending between two diametrically opposing regions of the seal-forming structure 3100, the septum region 3132 being configured to adhere in use to the columella.

[0174] The forms of the technology shown in Figs. 8 to 22 are also configured to seal to regions of the patient’s face around and proximate the patient’s nares, including some of the regions described earlier in relation to the other forms of the technology.4.3.1.3 Composition of the Seal-Forming Structure

[0175] In certain forms of the present technology, the seal-forming structure 3100 is constructed from a material having one or more of the following properties: biocompatibility; soft; flexible; stretchable and optionally resilient. In exemplary forms of the technology, the seal-forming structure 3100 is formed from silicone, a thermoplastic elastomer (TPE) or plastic such as polyurethane. In other forms, the seal-forming structure 3100 is formed from a textile, fabric and / or foam material.

[0176] In the case of forms of the technology in which an adhesive is used to adhere the seal-forming structure 3100 to the patient’s face, any form of adhesive may be used, and adhesives may be applied to any suitable substrate, which may include materials such as mentioned above, for example silicone, TPE or polyurethane. For example, a rubber zinc oxide adhesive may be used. In other forms, other adhesives may be used, for example acrylic or acrylate adhesives, or silicone adhesives.

[0177] The adhesives may be provided in the form of adhesive tapes, in which the adhesive is already provided on a substrate (i.e. the tape), which may be advantageously used as the seal-forming structure 3100, or part thereof, or may be readily attached to the seal-forming structure 3100. Examples of suitable tapes are the 3M™ Nexcare™ tape and Leukoplast tape. In some forms, the material may comprise a rayon substrate to which an adhesive is applied. In one form, the sealforming structure may be formed from, or may comprise, 3M™ Product No. 2484 (which uses a silicone adhesive, “Hi-Tack 3M medical silicone adhesive”), 3M™Medical tape 9833 (which uses an acrylic / acrylate adhesive on a polyurethane substrate), or a similar type of product or a product having similar structures and / or properties. Multiple layers of a tape or product may be used to form the seal-forming structure 3100.

[0178] In general, the seal-forming structure 3100 may comprise one or more adhesive layers 3190. It should be understood that, unless stated otherwise, each adhesive layer 3190 may take any form in which one or both sides of the layer are adhesive, including the aforementioned tapes or other substrates to which an adhesive has been applied. In some forms, the adhesive layer 3190 may comprise the layer of adhesive substance applied to a substrate.

[0179] In the forms of the technology shown in Figs. 12, 13, 14A and 14B, the seal-forming structure 3100 may comprise a flange 3105 connected to the patientfacing (or posterior) side of the plenum chamber 3200. The flange 3105 may extend radially outwards from the opening in the patient-facing side of the plenum chamber 3200 in all directions. The flange 3105 may be formed from silicone or TPE, for example, and in some forms may be formed from the same material as is used to form the plenum chamber 3200, for example the flange 3105 may be integrally formed with the plenum chamber 3200. In these forms, the adhesive may be applied to the patient-facing side of the flange 3105. In these forms, the entirety of, or a substantial part of, the adhesive surface 3102 of the seal-forming structure 3100 may be on the patient-facing side of the flange 3105, or in alignment with it. For example, in these forms, the adhesive layer 3190, which comprises the adhesive surface 3102, may not extend radially outwardly from the flange 3105, as contrasted with other forms described later.

[0180] In some forms, for example as shown in Figs. 14 A and 14B, the adhesive may be applied to the patient-facing side of the flange 3105 in the form of one or more adhesive layers 3190. Each adhesive layer 3190 may cover a substantial proportion of the patient-facing side of the flange 3105, for example substantially all of the patient-facing side of the flange 3105.

[0181] In other forms, for example the forms of technology illustrated in Figs. 15-18A, 19 and 21-22, the adhesive surface 3102 of the seal-forming structure 3100 may extend radially outwardly from the flange 3105, or the seal-forming structure 3100 may not comprise a flange (as in the example of Fig. 16). For example, as shown in Figs. 15 and 19, the flange 3105 may extend radially outwardly from the opening on the patient-facing side of the plenum chamber 3200 to a lesser degreethan the radially outward extent of the adhesive surface 3102 of the seal-forming structure 3100, e.g. to a lesser degree than in the forms shown in, for example, Figs. 14A and 14B. In these forms, one or more adhesive layers 3190 may extend radially outwardly from the flange 3105.

[0182] Each adhesive layer 3190 may be formed with a hole in it, for example in a central region. The hole may be sized and shaped to substantially match the opening in the seal-forming structure 3100 and the opening in the patient-facing side of the plenum chamber 3200 so as to align with these openings when the patient interface 3000 is assembled and to allow the flow of breathable gas through the openings and hole to the patient’s airways. Each adhesive layer 3190 may further be formed with notches 3110 as described below.

[0183] In some forms, each adhesive layer 3190 is a double-sided adhesive layer, i.e. a substrate which has adhesive on both surfaces. The double-sided nature of the adhesive layer may be achieved by the adhesive layer being provided in this form from a supplier, e.g. double-sided adhesive tape, or through the application of additional adhesive to the non-adhesive side of an originally single-sided adhesive adhesive.

[0184] In the form shown in Fig. 14A, the seal-forming structure 3100 comprises a single double-sided adhesive layer 3190. The non-patient-facing side of this adhesive layer 3190 is adhered to the patient-facing side of the flange 3105. The patient interface 3000 may comprise a patient-facing removable layer 3120 which is configured to cover the patient-facing side of the adhesive layer 3190 until the patient is ready to adhere the seal-forming structure 3100 to their face. The patientfacing removable layer 3120 may be removed from the adhesive layer 3190 prior to the seal-forming structure 3100 being adhered to the face. The patient may be provided with replacement portions of adhesive layer 3190 to replace on the flange 3105 each use of the patient interface 3000 or every few uses.

[0185] In the form shown in Fig. 15, the seal-forming structure 3100 comprises a single adhesive layer 3190. The adhesive layer 3190 may have a patient-facing side substantially fully coated with an adhesive. The seal-forming structure 3100 may further comprise an adhesive surface on a non-patient-facing side, for example a ring of adhesive material 3122 for adhering the plenum chamber 3200 to the seal-forming structure 3100. The ring of adhesive material 3122 may occupy part of a non-patient- facing side of the adhesive layer 3190 and around the opening hole in the sealforming structure 3100 through which the breathable gas is conveyed to the patient inuse. Again the patient may be provided with replacement portions of adhesive layer 3190 to replace each use of the patient interface 3000 or every few uses.

[0186] In other forms, for example as shown in Figs. 14B, 17, 19 and 21-22, the seal-forming structure 3100 comprises multiple adhesive layers 3190, for example two adhesive layers 3190a and 3190b. When the seal-forming structure 3100 is assembled, the non-patient-facing side of the first adhesive layer 3190a may be adhered to the patient-facing side of the flange 3105, the non-patient-facing side of the second adhesive layer 3190b may be adhered to the patient-facing side of the first adhesive layer 3190a and the patient-facing side of the second adhesive layer 3190b may be adhered to the patient’s face when the patient interface 3000 is in use. Prior to assembly of the seal-forming structure 3100, the non-patient-facing side of the first adhesive layer 3190a may be covered by a non-patient-facing removable layer 3180 to protect the adhesive before assembly and the patient-facing side of the second adhesive layer 3190b may be covered by a patient-facing removable layer 3120 to protect the adhesive before assembly. This layered assembly of multiple layers (for example layers 3180, 3190a, 3190b and 3120) may be supplied separately to the plenum chamber 3200. In addition, multiple such layered assemblies may be provided and the patient may replace the layered assemblies for different uses of the patient interface 3000, for example the layered assembly may be replaced each night or every few nights.

[0187] In some forms, the second adhesive layer 3190b may be an adhesive layer particularly suited to adhering to a patient’s skin, for example medical tape, while the first adhesive layer 3190a may be more suitable for adhering to the flange 3105. In some forms, the medical tape used as the second adhesive layer 3190b may not be double-sided and therefore a double-sided first adhesive layer 3190a may be used to adhere the medical tape to the plenum chamber 3200. In some forms, the first adhesive layer 3190a may be formed from a material having a silicone-based and / or rubber-based adhesive on one side and an acrylic-based adhesive on the other side, with both adhesives carried by a carrier formed from a plastic, for example a polyester film such as PET or polyurethane. The silicone- and / or rubber-based side may be suitable for bonding the seal-forming structure 3100 to the plenum chamber 3200 while the acrylic-based adhesive may be suitable for bonding the seal-forming structure 3100 to the patient’s face. For example, the first adhesive layer 3190a may be formed from 3M™ Double-Coated Tape 9731.

[0188] In the case of the form shown in Fig. 14B, each adhesive layer 3190a and 3190b may be sized and shaped similarly to the size and shape of the patient-facing side of the flange 3105 so that each adhesive layer 3190 covers a substantial part of the patient-facing area of the flange 3105 but does not extend radially outwardly from the edges of the flange.

[0189] In the case of the form shown in Figs. 17, 19 and 21-22, the first adhesive layer 3190a may be sized and shaped similarly to the size and shape of the flange 3105, e.g. ring-shaped. The first adhesive layer 3190a may be double-sided. The second adhesive layer 3190b may have a larger area than the first adhesive layer 3190a and may extend radially outwardly from the first adhesive layer 3190a, and consequently the flange 3105. The second adhesive layer 3190b may be single-sided, and may be a medical tape suitable for adhering to the patient’s skin. The non- patient-facing removable layer 3180 may be sized and shaped to match the size and shape of the first adhesive layer 3190a and the patient-facing removable layer 3120 may be sized and shaped to match the size and shape of the second adhesive layer 3190b.

[0190] In some forms, for example as shown in Fig. 22B, the seal-forming structure 3100 may comprise one or more tabs 3192 projecting outwardly from an outer edge. For example, in some forms, such as shown in Fig. 22B, there may be two tabs 3192. The tabs 3192 may be positioned substantially diametrically opposite each other. In some forms, such as shown in Fig. 22B, the tabs 3192 may project outwardly from lateral edges of the seal-forming structure 3100. The tabs 3192 may assist the patient to remove the seal-forming structure 3100 from their face after use by peeling at the comers of the tabs and grasping them. In the form shown in Fig. 22B the tabs 3192 are relatively wide and generally rectangular shaped (with rounded comers) but in other forms the tabs 3192 may have another shape, for example they may be triangular, square, semi-circular, etc, optionally with rounded corners where comers are present.

[0191] In some forms, for example as shown in Fig. 22B, one or more tab covers 3124 may be provided. Prior to the patient interface 3000 being donned, each tab cover 3124 may be mounted to, for example adhered to, the patient-facing side of a tab 3192 of the seal-forming structure. The patient-facing side of tab cover 3124 may be non-adhesive. The tab covers 3124 may prevent the tabs 3192 of the seal-forming structure 3100 from adhering to the removable layer 3120, therefore helping the patient to remove the removable layer 3120 from the seal-forming stmcture 3100, i.e.by grasping the tab 3192 and tab cover 3124 together and peeling the seal-forming structure 3100 away from the removable layer 3120.

[0192] In some forms, for example as shown in Figs. 21 and 22, the removable layer 3120 may comprise one or more projections 3126 projecting outwardly from an outer edge. The projections 3126 may be used to secure the removable layer in place on a holder so that the patient can assemble the patient interface 3000 and prepare it for donning, e.g. by mounting the plenum chamber 3200 to the seal-forming structure 3100 and by removing the seal-forming structure 3100 from the removable layer 3120.

[0193] In some forms, a fluid adhesive may be applied to a surface of the sealforming structure 3100, for example in the form of a spray.

[0194] In some forms, the seal-forming structure 3100 may be attached to a patient’s face using one or more action-release adhesives. The action-release adhesive(s) may be configured so that its adhesive strength is reduced when an “action” is effected. The reduction in the adhesion strength may be sufficient to allow the seal-forming structure 3100 to be easily removed from the patient’s face while causing an acceptable level of discomfort. In some forms, the action may be some change or effect that is applied to the adhesive, or to a component (such as the seal-forming structure 3100) to which the adhesive is applied. For example, the patient interface 3000 may comprise a seal-forming structure 3100 having an adhesive surface 3102 where the adhesive strength of the adhesive surface 3102 can be reduced by the deformation of the adhesive surface 3102. The deformation may be a stretch action, i.e. the adhesive surface 3102 may be provided with, or formed from, a stretch -release adhesive. A stretch -release adhesive may have certain adhesive properties only when the adhesive surface 3102 is substantially unstretched. The adhesive surface 3102 may be configured to have reduced and / or no adhesive properties when the adhesive surface 3102 is stretched. In certain forms, acrylate- based adhesives may be used as a stretch-release adhesive for adhesive surface 3102, for example Fixomull™ or 3M™ Stretch Release Tape.4.3.1.4 Notches

[0195] In certain forms of the technology, for example as illustrated in Figs. 9 to 22, the seal-forming structure 3100 may be configured with one or more notches 3110. The notches may be formed in an edge of the seal-forming structure 3100, i.e. an outer perimeter of the seal-forming structure 3100. The notches 3110 may act todeter or prevent the seal-forming structure 3100 from forming crumples when adhered to the patient’s face. Such crumples may occur because of differences between the contours of the patient’s face and the natural three-dimensional shape of the seal-forming structure 3100. Since such crumples may provide regions where pressurised gas may leak, avoiding them may be advantageous for provision of therapy. Also, after a prolonged use, such as overnight, the crumples may mark the patient’s skin and / or be uncomfortable.

[0196] When adhering a seal-forming structure 3100 to a patient’s face, crumples may be likely to appear in certain regions of the seal-forming structure 3100, for example regions that are configured to adhere to regions of the patient’s face that have a substantially non-planar shape, e.g. abrupt changes in orientation. In certain forms, the notches 3110 may be formed in a region or regions of the sealforming structure 3100 that are configured to adhere to such regions of the patient’s face. In certain forms, such regions of the patient’s face may be on, around or proximate the patient’s nose.

[0197] Certain exemplary forms of the technology in which a seal-forming structure 3100 is configured with one or more notches 3110 will be described in the paragraphs below and with reference to the figures. These forms have notches 3110 in certain positions on the seal-forming structure 3100. Also, different shapes and sizes of notches 3110 are described in relation to different forms of the technology. It should be appreciated that these exemplary forms are not limiting to the technology and other forms not expressly illustrated or described may have different combinations of notches 3110 in various positions and / or notches 3110 of different shapes and / or sizes. For example, in other forms, the position, shape and / or size of a notch in one form may be applied to a notch of another form. Other forms may omit notches 3110 described in the exemplary forms.

[0198] Where a seal-forming structure 3100 is formed from multiple layers, for example the seal-forming structures shown in Figs. 14, 17, 19, 21 and 22, each layer of the seal-forming structure 3100 may include appropriately sized, shaped and positioned notches so that, when the layers are assembled together, the notches 3110 as described herein are formed. For the sake of simplicity in the description and drawings, the notches of each individual layer are not all described and labelled.

[0199] Figs. 9- 18 A, 19 and 21-22 illustrate a plenum chamber 3200 and a sealforming structure 3100 of an exemplary patient interface 3000 in which the sealforming structure 3100 is configured with multiple notches 3110a, 3110b, 3110c and31 lOd provided at different positions in the outer edge of the seal-forming structure. Fig. 11 illustrates the seal-forming structure 3100 of Figs. 9 and 10 adhered to a patient’s face.

[0200] One notch 3110a is formed in a region of the seal-forming structure 3100 that is configured to adhere to the patient’s pronasale when the seal-forming structure 3100 is adhered to the patient’s face. This notch 3110a may be formed in a superior edge of a region of the seal-forming structure 3100 that, in use, may be positioned on the patient’s medial plane, i.e. the notch 3110a may be positioned laterally in the middle of the seal-forming structure 3100.

[0201] Two further notches 3110b and 3110c may be formed in regions of the seal-forming structure 3100 that are configured in use to adhere to or proximate the patient’s nasal ala as shown in Fig. 11. The notches 3110b and 3110b may be located in a superior edge of the seal-forming structure 3100. Notches 3110b and 3110c may be positioned lateral to, and on either side of, the medial plane when the seal-forming structure 3100 is positioned in use, i.e. notch 3110b is formed in a region of the sealforming structure 3100 that is configured to be located on one side of the medial plane during use, and notch 3110c is formed in a region of the seal-forming structure 3100 that is configured to be located on the other side of the medial plane during use. Notches 3110b and 3110c may be positioned medially inward from the lateral edge of the seal-forming structure 3100, for example the notches 3110b and 3110c may be located approximately halfway between a medial (or central) region and the lateral outer edge of the seal-forming structure 3100.

[0202] The notches 3110a, 3110b and 3110c may be substantially V-shaped. This may enable the notches 3110 to fan further open or fan further closed when adhered to a region of the patient’s face, depending on the contour of that region. In the illustrated form, the notch 3110a may be formed with a wider V-shape than notches 3110b and 3110c, although in other forms notch 3110a may be formed with a narrower V-shape, or each of notches 3110a, 3110b and 3110c may be formed with a similar V-shape.

[0203] The seal-forming structures 3100 illustrated in Figs. 9-22 further form a notch 31 lOd formed in a region that is configured to adhere to the patient’s lip superior region in use. The notch 31 lOd may be located in an inferior edge of the seal-forming structure 3100. The notch 31 lOd may be formed in a region of the sealforming structure that is configured to adhere to a region of the patient’s face positioned on or proximate the medial plane in use, for example, in use the notch31 lOd may lie on the patient’s medial plane. In some forms, for example as illustrated in Figs. 9 and 10, the notch 3110d is relatively wide compared to the other notches 3110a-3110c, for example it may extend laterally across the patient’s face substantially the width of the patient’s mouth, i.e. the seal-forming structure 3100 may be configured such that the notch 31 lOd has a width that is substantially equal to, or greater than, the width of a typical patient. In such forms, the notch 31 lOd may be described as straddling across the medial plane of the patient when the sealforming structure 3110 is in the operative position in use. This size of notch 31 lOd may assist in positioning the seal-forming structure 3100 around the patient’s mouth without adhering to the upper vermilion (see Fig. 2C), which may be uncomfortable. In other forms, for example in Figs. 11-22, the notch 31 lOd may be much narrower, for example significantly narrower than the patient’s mouth, e.g. a few millimetres across.

[0204] The seal-forming structure illustrated in some forms of the technology, for example Figs. 9-11 may be formed such that the lateral edges of the seal-forming structure 3100 extend sufficiently far laterally that they adhere to the patient’s cheeks in use. Alternatively, the lateral edges of the seal-forming structure 3100 may extend sufficiently far laterally that they adhere to the patient’s nasolabial sulcus region in use.

[0205] In other forms of the technology, the patient interface 3000 comprises a seal-forming structure 3100 as illustrated in Figs. 12-22. In these forms, the superior notch 3110a is formed in a region of the seal-forming structure 3100 that is configured in use to adhere to the patient’s nose, for example the pronasale. The sealforming structures 3100 illustrated in Figs. 12-22 may further form an inferior notch 31 lOd provided to a lower edge of a medial region of the seal-forming structure 3100 which lies substantially inferior to the opening 3202. The inferior notch 3110d may be formed in a region of the seal-forming structure 3100 that, in use, is configured to adhere to the patient’s lip superior region, for example on or substantially near the patient’s subnasale.

[0206] The seal-forming structure 3100 illustrated in Figs. 12-14 may further form first and second lateral notches 3110b and 3110c. These notches may, in use, extend substantially laterally inwardly towards the patient’s medial plane from a lateral edge of the seal-forming structure 3100 towards the patient’s medial plane.

[0207] The lateral notches 3110b and 3110c may be substantially slit-shaped. For example, the notches 3110b and 3110c may have edges that are substantiallyparallel to each other. This may enable the notches 3110 to fan further open or fan further closed when adhered to a region of the patient’s face, depending on the contour of that region. The seal-forming structure 3100 may further be formed such that the lead-in to each of the notches 3110b and 3110c is curved. This may avoid a sharp corner being present on the seal-forming structure, which may be uncomfortable or liable to peel away from the patient’s face during use.

[0208] The seal-forming structure 3100 illustrated in Figs. 12-14 may be configured such that, when adhered to a patient’s face, the regions of the sealforming structure 3100 immediately superior to the notches 3110b and 3110c adhere to the patient’s respective nasal ala and the regions of the seal-forming structure 3100 immediately inferior to the notches 3110b and 3110c adhere to the region of the patient’s lip superior region that is adjacent and inferior to the nasal ala. That is, regions of the seal-forming structure 3100 adjacent notches 3110b and 3110c may adhere proximate the patient’s alar crest points (see Fig. 2C). Consequently, the presence of lateral notches 3110b and 3110c may assist the seal-forming structure 3100 to seal across the crease in between the nasal ala and the lip superior.

[0209] Forms of the technology are not limited by the number of notches 3110 formed in the seal-forming structure 3100 thereof. However, in certain forms, the number of notches 3110 is not so great that the seal-forming structure 3100 becomes so difficult to handle that it is difficult to position on the face without crumpling or folding the seal-forming structure 3100, e.g. the regions of the seal-forming structure 3100 between the notches 3110. The tolerable number of notches 3110 may vary depending on the configuration of the patient interface 3000, including the size and shape of the notches 3110. For example, longer notches 3110 will tend to permit a greater amount of flexibility in the seal-forming structure 3100 compared to shorter notches 3110, and therefore fewer longer notches 3110 may be tolerated.

[0210] In certain forms, for example the form of the technology shown in Figs. 12-22, the seal-forming structure 3100 may be formed to be substantially symmetric around an axis that is oriented in the lateral-medial direction when the seal-forming structure 3100 is adhered to the patient’s face during use. Such an axis is illustrated as A-A in Fig. 12. Explained another way, when the seal-forming structure 3100 is adhered to the patient’s face, the axis may be perpendicular to the patient’s mid- sagittal plane. An advantage of this is that the seal-forming structure 3100 may be applied to the patient’s face in two different orientations, i.e. it does not matter whether the patient orients the seal-forming structure 3100 one way up or another.4.3.1.5 Shape retainer

[0211] In certain forms of the technology, the patient interface 3000 may comprise one or more shape retainers 3170. The shape retainer(s) may be configured to promote retention of the shape of the seal-forming structure 3100 before the sealforming structure is made to adhere to the patient’s face, for example to a sufficient extent to prevent the seal-forming structure 3100 from crumpling, folding or sagging in a way that makes it difficult for the patient 1000 to affix the seal-forming structure 3100 to their face.

[0212] The one or more shape retainers 3170 may be one or more components, an assembly or a structure which are formed with a shape and / or out of materials to provide a predetermined level of stiffness suitable to promote the desired level of retention of the shape of the seal-forming structure 3100. In certain forms, the one or more shape retainers 3170 are comprised as part of the seal-forming structure 3100. In other forms, the shape retainer(s) 3170 may be attached to the seal-forming structure 3100 to promote retention of the shape of the seal-forming structure 3100, for example by stiffening one or more regions of the seal-forming structure 3100.

[0213] In certain forms, the plenum chamber 3200, which may be formed so as to be more rigid than the seal-forming structure 3100, and to which the seal-forming structure 3100 is provided, may act to help retain the shape of the seal-forming structure 3100. The region of the seal-forming structure 3100 connected to the plenum chamber 3200 may be maintained in its shape by the relatively rigid plenum chamber 3200, and this may also help maintain the shape of other parts of the sealforming structure 3100. Consequently, the plenum chamber 3200 may be considered to be a shape retainer in some forms of the technology.

[0214] In some forms, the one or more shape retainers 3170 may be removably mounted to the seal-forming structure 3100, with the design intent of the shape retainers 3170 being removed prior to the seal-forming structure 3100 being donned, i.e. adhered to the patient’s face. In exemplary such forms, for example the form shown in Figs. 12-15, 17 and 19-22, the removable layer 3120 may act to help retain the shape of the seal-forming structure 3100 prior to removing the removable layer 3120, and consequently may be considered to be a shape retainer in some forms. To act in this way, the removable layer 3120 may be formed so as to be relatively rigid in comparison to the seal-forming structure 3100, for example the removable layer3120 may be formed from a material and / or in a shape that is relatively rigid. In some forms, the one or more shape retainers 3170 may be removably mounted to the second adhesive layer 3190b, i.e. the adhesive layer 3190b that is adhered to the patient’s face when the patient interface 3000 is in use.

[0215] The exemplary patient interfaces 3000 illustrated in Figs. 15-19 and 21- 22 are other forms of the technology in which the patient interface 3000 comprises at least one shape retainer 3170 which is configured to promote retention of the shape of the seal-forming structure 3100 before the seal-forming structure 3100 is made to adhere to the patient’s face. In these forms, the shape retainer 3170 comprises a loop which extends around a substantial part of the outer perimeter of the seal-forming structure 3100. The shape retainer 3170 acts to provide shape retention to the radially outer regions of the seal-forming structure 3100, and thereby acts to promote all of the seal-forming structure 3100 to retain its shape until the shape retainer 3170 is removed.

[0216] The shape retainers 3170 of Figs. 15-19 and 21-22 may be formed from a material and / or having a shape so as to make the shape retainer 3170 more rigid than the seal-forming structure 3100. For example, the shape retainer 3170 may be formed from a material that is thicker than the material used to form the seal-forming structure 3100. Additionally, or alternatively, the shape retainer 3170 may be formed from a material that is harder than the material used to form the seal-forming structure 3100. In some exemplary forms, the shape retainer 3170 may be provided with an additional rigidising structure to provide additional rigidity, for example rigidising ribs. The shape retainer 3170 may not be so rigid that its shape cannot be altered by the patient so that the patient is still able to flex the shape retainer 3170 and seal-forming structure 3100 when adhering the patient interface 3000 to their face. In this regard, the shape retainer 3170 may be described as semi-rigid. In one example, the shape retainer 3170 may be formed from paper, for example kraft paper.

[0217] In the forms of the technology illustrated in Figs. 15-19 and 21-22, the shape retainer 3170 is configured to be positioned on a non-patient-facing side of the seal-forming structure 3100. For example, the shape retainer 3170 may be adhered to the non-patient-facing side of the seal-forming structure 3100. In some forms, an adhesive may be used to adhere the shape retainer 3170 to the seal-forming structure 3100. In such forms, the adhesive may be applied to the patient-facing side of theshape retainer 3170 or to the non-patient-facing side of the seal-forming structure 3100, or both.

[0218] The shape retainer 3170 may be removably mounted to the seal-forming structure 3100. For example, where adhesive is used to mount the shape retainer 3170 to the seal-forming structure 3100, the strength of the adhesive may be relatively low to enable the shape retainer 3170 to be easily removed from the sealforming structure 3100 by the patient. In other forms, the shape retainer 3170 may be weakly held in place relative to the seal-forming structure 3100 through a natural tackiness between the seal-forming structure 3100 and the shape retainer 3170. An advantage of the shape retainer 3170 being provided to a non-patient-facing side of the seal-forming structure 3100 is that the patient is able to position the seal-forming structure 3100 on their face while the shape retainer 3170 is still in position. Then, when the seal-forming structure 3100 is adhered to the face, the shape retainer 3170 may be removed, as has occurred in the example of Fig. 16.

[0219] In other forms, the shape retainer 3170 may be positioned on a patientfacing side of the seal-forming structure 3100. The mechanism of retention in these forms may be the same or similar to as explained above for forms in which the shape retainer 3170 is positioned on a non-patient-facing side of the seal-forming structure 3100. An advantage of such forms is that the same adhesive surface of the sealforming structure 3100 used to adhere the seal-forming structure 3100 to the patient’s face may be used to retain the shape retainer 3170 in position before its removal.

[0220] In the forms shown in Figs. 15-19 and 21-22, the shape retainer 3170 comprises a loop which extends around a substantial part of the outer perimeter of the seal-forming structure 3100. In some forms, the shape retainer 3170 is positioned around the radially outermost portions of the seal-forming structure 3100 while in other forms the shape retainer 3170 is positioned in a loop around radially outer portions of the seal-forming structure 3100, but may not necessarily be provided to the outermost portions all around the perimeter of the seal-forming structure 3100.

[0221] In forms in which the shape retainer 3170 is in the form of a loop, the shape retainer 3170 forms a hole radially inside the loop. In addition, when the shape retainer 3170 is mounted to the seal-forming structure 3100, there may be a region of the non-patient-facing side of the seal-forming structure 3100 surrounding the opening in the seal-forming structure 3100 that allows a flow of breathable gas to be delivered to the patient that is not covered by the shape retainer 3170, i.e. theremay be a gap between the opening and the radially inner edge of the shape retainer 3170. In some forms the uncovered region may be a substantial proportion of the non-patient-facing side of the seal-forming structure 3100, e.g. it may be approximately 30-70% of the area of the non-patient-facing side of the seal-forming structure 3100. It has been found that a shape retainer in this form may be more advantageous than a shape retainer 3170 that covers all or a significant proportion of the non-patient-facing side of the seal-forming structure 3100 because, in the latter case, the shape retainer 3170 may provide too much rigidity to the seal-forming structure 3100 so that it becomes difficult to apply to the face.

[0222] In some forms the patient interface 3000 may comprise an adhesive surface on a non-patient facing side for adhering the plenum chamber 3200 to the seal-forming structure 3100. For example, in the exemplary forms shown in Figs. 15, 17, 21 and 22, the patient interface 3000 may comprise a ring of adhesive material 3122 on a non-patient facing side for adhering the plenum chamber 3200 to the sealforming structure 3100. In some forms, the ring of adhesive material 312 may entirely surround the opening in the seal-forming structure 3100 through which the flow of breathable gas passes. In other forms, the ring of adhesive material 312 may partly surround the opening and the sector around the opening without adhesive material may form a part of a vent structure for the exhaustion of exhaled gases.

[0223] The ring of adhesive material 3122 (or more generally the adhesive surface on the non-patient facing side) may be covered by a non-patient-facing removable layer 3180 to protect the adhesive before the plenum chamber 3200 is brought into contact with the ring of adhesive material 3122. In this form, there may be an annular gap between the ring of adhesive material 3122 and the radially inner edge of the shape retainer 3170 and an annular region of the non-patient-facing side of the seal-forming structure 3100 may be uncovered by the shape retainer 3170 due to this gap. The annular gap may vary in size around the perimeter of the gap. For example, as shown in Figs. 17, 18A, 19, 21 and 22, the size of the gap may be larger in lateral regions compared to inferior and / or superior regions. In these forms, the gap is very small in inferior and superior regions. In some forms, there may be substantially no gap in some regions, for example in inferior and / or superior regions.

[0224] The shape retainer 3170 may have a constant radial thickness around the loop or, as shown in Figs. 15, 17-19, 21 and 22, the radial thickness of the shape retainer 3170 may vary around the loop. The radial thickness of the shape retainer 3170 may be thicker in regions that would benefit from a greater amount of shaperetention. For example, the lateral regions of the shape retainer 3170 that are provided to lateral regions of the seal-forming structure 3100 (from the perspective of when the seal-forming structure 3100 is in position on the patient’s face) may be radially thicker than other regions, for example thicker than inferior and superior medial regions of the shape retainer 3170, as shown in Figs. 15, 17-19, 21 and 22. The lateral regions of the seal-forming structure 3100 may benefit from more shape retention in the illustrated form because these regions have a larger area than the inferior and superior medial regions of the seal-forming structure 3100 and are further from the rigid support of the plenum chamber 3200 when the patient interface 3000 is assembled and therefore may be more liable to flop or crumple when the patient is adhering the seal-forming structure 3100 to their face. The shape and size of the outer perimeter of the shape retainer 3170 may exactly or substantially correspond to the shape and size of the outer perimeter of the seal-forming structure 3100, which may in some forms be the same as the outer perimeter of the second adhesive layer 3190b. For example, where the seal-forming structure 3100 has one or more notches in its edge, the shape retainer 3170 may have similar or identical notches in its edge, as shown in Figs. 15, 17-19, 21 and 22. Similarly, where the sealforming structure 3100 has one or more projections outwardly from its edge, for example tabs 3192, the shape retainer 3170 may comprise similarly shaped tabs 3176 projecting from its outer edge.

[0225] In certain forms, for example the forms illustrated in Figs. 17, 18B, 19, 21 and 22, a discontinuity 3174 may be formed in the shape retainer 3170 which may extend from an inner edge to an outer edge of the shape retainer. In some forms, for example as shown in Figs. 18B, 19, 21 and 22, the discontinuity 3174 may be a slit (e.g. a cut having substantially no width) while in other forms, for example as shown in Fig. 17, the discontinuity 3174 may be a gap in the shape retainer 3170. In this latter form, the shape retainer 3170 may form an incomplete loop having a first end 3170A and a second end 3170B with a gap between the first end 3170A and the second end 3170B. The gap may be quite small so that the first end 3170A may be located close to the second end 3170B in use, for example the circumferential width of the gap may be significantly less than the circumference of the loop. In certain forms, the gap may be of the order of a few millimetres or less in circumferential width. In use, a patient may grasp the shape retainer 3170 on one side of the discontinuity 3174, for example the first end 3170A or the second end 3170B, in order to remove the shape retainer 3170 from the seal-forming structure 3100.

[0226] In alternative forms of the technology, such as shown in Figs. 15 and 18, the loop of the shape retainer 3170 may be continuous without any discontinuities. In other forms of the technology, the loop of the shape retainer 3170 may have multiple discontinuities 3174, which may be slits and / or gaps.

[0227] In certain forms of the technology, for example as illustrated in Figs. 18A, 18B and 19, 21 and 22, the shape retainer 3170 may comprise one or more tabs 3172 configured to be grasped by a user for removing the shape retainer 3170 from the seal-forming structure 3100. The tabs may be regions of the shape retainer 3170 that protrude outwardly from an edge of another part of the shape retainer 3170 for ease of grasping. As illustrated in Figs. 18A, 18B and 19, 21 and 22, at least one tab 3172 may extend radially inwards from the loop of the shape retainer 3170 towards the opening in the seal-forming structure 3100 for delivering breathable gas to the patient. An advantage of this configuration is that the tab 3172 does not extend outwardly from the footprint of the seal-forming structure 3100 and therefore may not be unintentionally caught and pulled away from the seal-forming structure 3100. In alternative forms, the tab 3172 may extend radially outwards from the loop of the shape retainer 3170.

[0228] The tab or tabs 3172 may be positioned at any one or more circumferential positions around the loop of the shape retainer 3170. For example, the tab 3172 may extend from an outer lateral region of the loop and radially inwardly so that, when the seal-forming structure 3100 is in position on a patient’s face, the tab 3172 extends in a lateral-medial direction. In the form illustrated in Fig. 26A, the shape retainer 3170 comprises a first tab 3172a and a second tab 3172b located either side of the patient’s medial plane in use. The first tab 3172a and the second tab 3172b may be configured to extend radially inwards from the loop of the shape retainer 3170.

[0229] The patient-facing side of tab 3172 may be non-adhesive so that the tab 3172 does not adhere to the non-patient-facing side of the seal-forming structure 3100 and can be readily grasped by the user. In some forms, for example as shown in Fig. 22B, the patient interface 3000 may comprise a tab cover 3178 that is mounted to, for example adhered to, the patient-facing side of tab 3172. The patient-facing side of tab cover 3178 may be non-adhesive. In other forms, the non-adhesive nature of the patient-facing side of tab 3172 may be achieved by not applying an adhesive to the part of the shape retainer 3170 that comprises the tab.4.3.1.6 Non-Patient-Facing Removable Layer

[0230] It has already been explained that, in certain forms of the technology, the seal-forming structure 3100 may comprise a non-patient-facing removable layer 3180 to protect an adhesive on a non-patient-facing side of a layer of the sealforming structure, for example adhesive layer 3190, before adhering the layer to the patient-facing side of the flange 3105 or to the plenum chamber 3200. Exemplary forms of the non-patient-facing removable layer 3180 are illustrated in Figs. 14B, 17 and 21 to 22. The non-patient-facing removable layer 3180 may alternatively be referred to as a “release liner”.

[0231] In the examples of Figs. 18, 19, 21 and 22, the non-patient-facing side of the adhesive layer 3190 may carry a ring of adhesive material 3122 for adhering the adhesive layer 3190 to the flange 3105 or to the plenum chamber 3200. The ring of adhesive material 3122 may be covered by the non-patient-facing removable layer 3180 to protect the adhesive before the plenum chamber 3200 is brought into contact with the ring of adhesive material 3122. In such examples, the non-patient-facing removable layer 3180 may be similarly ring-shaped so as to entirely cover the ring of adhesive material 3122 but it may not cover other regions of the non-patient-facing side of the adhesive layer 3190. That is, the non-patient-facing removable layer 3180 may be formed with a hole therein. When the non-patient-facing removable layer 3180 is positioned to cover the ring of adhesive material 3122, the hole may substantially align with the hole in the adhesive layer 3190, i.e. the opening in the seal-forming structure 3100 through which breathable gas is delivered to the patient when the patient interface 3000 is in use. In other forms, the non-patient-facing removable layer 3180 may be formed without a hole therein, and the hole in the sealforming structure 3100 may be revealed once the removable layer 3180 is removed.4.3.1.6.1 Slit

[0232] In certain forms, the non-patient-facing removable layer 3180 has formed therein one or more slits 3182. Different forms of the technology may have slits 3182 in different positions and orientations and some examples will be described below.

[0233] The presence of one or more slits 3182 of the type described below may help a user to remove the non-patient-facing removable layer 3180 without causing unwanted effects on certain parts of the seal-forming structure 3100 and, in particular, the layered assembly additionally formed of one or more adhesive layers 3190, the patient-facing removable layer 3120 and, optionally, the shape retainer3170. When the non-patient-facing removable layer 3180 is removed, for example with a peeling action, the pulling force on the non-patient-facing removable layer 3180 may be transmitted to the layered assembly, causing it to bend in the direction of the pulling force. In some cases, this bending may cause exposed regions of adhesive on the layered assembly to come into contact with another region of the layered assembly and to adhere to it. This may be unwanted and may be difficult for a user to undo and / or may cause wrinkling of the layered assembly if undone, which may make it difficult to ultimately adhere the seal-forming structure 3100 to the patient’s face, or may adversely affect the adhesion strength on the patient’s face. Additionally, or alternatively, the act of pulling off the non-patient-facing removable layer 3180 may result in delamination of a patient-facing removable layer 3120 from the patient-facing side of the adhesive layer 3190 in forms where a patient-facing removable layer 3120 is present. If this delamination occurs before it is desired by the user, this may result in difficulties for the user handling the seal-forming structure 3100 or adversely impact the adhesion of the seal-forming structure 3100 to the patient’s face, similarly to the problematic effects described above.

[0234] In exemplary forms, each slit 3182 may extend from an edge of the non- patient-facing removable layer 3180, i.e. from an edge region to a central region of the non-patient-facing removable layer 3180. In some forms, one or more of the slits 3182 may extend from a radially outer edge of the non -patient-facing removable layer to a radially inner edge of the non-patient-facing removable layer, i.e. the slit may extend across a ring-shaped non-patient-facing removable layer 3180 between the hole and the exterior circumference. In some forms, one or more of the slits 3182 may extend at least partially in an azimuthal direction around the non-patient-facing removable layer 3180.

[0235] A variety of forms of exemplary non-patient-facing removable layer 3180 are illustrated in Figs. 20A to 201.

[0236] The form of non-patient-facing removable layer 3180 shown in Figs. 19 and 20A has formed therein two slits 3182a and 3182b. The first slit 3182a extends from a radially outer edge of the non-patient-facing removable layer to a radially inner edge. The first slit 3182a may be positioned on an opposite side of the non- patient-facing removable layer 3180 from a tab 3184 (described below) but offset from being directly opposite, for example at approximately 120-160° azimuthally from the tab 3184, although the slit may be at other positions relative to the tab 3184 in other forms. The second slit 3182b extends inwardly from a radially outer edge ofthe non-patient-facing removable layer 3180. The position at which the second slit 3182b begins on the outer edge may be on an opposite side of the non-patient-facing removable layer 3180 from the tab 3184 but offset from being directly opposite, for example at approximately 120-160° azimuthally from the tab 3184 in the opposite direction from the azimuthal direction of the first slit 3182 from the tab. That is, the second slit 3182b may meet the outer periphery of the non-patient-facing removable layer 3180 azimuthally around from the first slit 3182 by approximately 40-120°. The second slit 3182b may extend approximately radially inwardly from the outer edge of the non-patient-facing removable layer 3180 and then turn to extend in an azimuthal direction around the non-patient-facing removable layer 3180. The end of the second slit 3182b may be in a central region of the non-patient-facing removable layer 3180 and may be proximate the first slit 3182a.

[0237] The form of non-patient-facing removable layer 3180 shown in Fig. 20B has a single slit 3182 formed in it extending from a radially outer edge of the non- patient-facing removable layer to a radially inner edge.

[0238] The form of non-patient-facing removable layer 3180 shown in Fig. 20C has a single slit 3182 formed in it extending from a radially outer edge of the non- patient-facing removable layer to a radially inner edge. The slit 3182 is located azimuthally immediately adjacent to tab 3184.

[0239] The form of non-patient-facing removable layer 3180 shown in Fig. 20D does not have a hole in it. The slit 3182 extends from one radially outer edge of the non-patient-facing removable layer 3180 to another radially outer edge and may pass through a central region of the non-patient-facing removable layer 3180. In this form, the slit 3182 may be sinuous in its shape, for example defining one or more tabs 3184 for the user to grasp to remove the non-patient-facing removable layer 3180.

[0240] In some forms, for example as shown in Fig. 20E, a slit (for example slit 3182b in Fig. 20E) may extend radially through a central portion of tab 3184. In the illustrated form, both slits 3182a and 3182b extend from a radially outer edge of the non-patient-facing removable layer to a radially inner edge. The slits 3182a and 3182b are diametrically opposite each other, although they may be arranged in different positions in other forms.

[0241] In some forms, for example as shown in Fig. 20F, the slit 3182 may extend azimuthally around all or a substantial part of the circumference of the non- patient-facing removable layer 3180. In the illustrated form, one end of the slit 3182 is at a radially outer edge of the non-patient-facing removable layer 3180 and theother end of the slit is at a radially inner edge, with the two ends approximately similarly located azimuthally. One end of the slit 3182, for example the radially inner end in the case of Fig. 20F, may be located immediately adjacent tab 3184.

[0242] The form of non-patient-facing removable layer 3180 shown in Fig. 20G has no slit but has a tab 3184.

[0243] In the form of non-patient-facing removable layer 3180 shown in Fig. 20H, there are two slits 3182a and 3182b with ends at an edge of the non-patient- facing removable layer 3180, for example at a radially inner edge, located on an opposite side of the non-patient-facing removable layer 3180 from the tab 3184 but offset from being directly opposite, for example at approximately 120-160° azimuthally from the tab 3184 in opposite directions from each other. Each slit extends outwardly from the inner edge of the non-patient-facing removable layer 3180 at a non-zero angle to the radial direction and then bends to extend in an azimuthal direction around the non-patient-facing removable layer 3180. The slits may bend towards each other such that ends of the two slits are proximate each other.

[0244] In the form of non-patient-facing removable layer 3180 shown in Fig.201, there are a plurality of slits 3182. The slits 3182 are collectively positioned on an opposite side of the non-patient-facing removable layer 3180 from the tab 3184. One of the slits 3182 may extend from a radially outer edge of the non-patient-facing removable layer to a radially inner edge. In the example shown, this slit is positioned diametrically opposite tab 3184. The non-patient-facing removable layer 3180 may have formed therein two sets of slits: a first set which extend radially inwards from a radially outer edge of the non-patient-facing removable layer 3180 and a second set which extend radially outwards from a radially inner edge of the non-patient-facing removable layer 3180. The first set of slits may be interleaved with the second set of slits so that, azimuthally around the non-patient-facing removable layer 3180, the slits alternate between the first and second sets. These slits may be located symmetrically on either side of the central slit in forms such as illustrated where such a slit is present.

[0245] It has been found that, in some cases, an arrangement of slits 3182 whereby, as the non-patient-facing removable layer 3180 is peeled away from the adhesive layer 3190 beginning with the tab 3184, the last part of the non-patient- facing removable layer 3180 to be removed from the adhesive layer 3190 has a relatively small area of adhesion to the adhesive layer 3190, for example is relatively thin, is advantageous for helping to prevent some or all of the above-describedadverse effects that may occur when peeling the non-patient-facing removable layer3180 in some other forms.4.3.1.6.2 Tab

[0246] As has been stated above, the non-patient-facing removable layer 3180 may comprise one or more tabs 3184. Each tab 3184 may be configured to be grasped by a user for removing the non-patient-facing removable layer 3180 from the seal-forming structure 3100, e.g. away from the adhesive layer 3190.

[0247] In some forms, for example as illustrated in Figs. 19, 20A, 20G, 20H and 201, the tab 3184 may extend radially outwards from a radially outer edge of the non- patient-facing removable layer 3180. In other forms, for example, as illustrated in Figs. 20C, 20E, and 20F, the tab 3184 may extend radially inwards from a radially inner edge of the non-patient-facing removable layer 3180.

[0248] In some forms, the example as illustrated in Figs. 19, 20A, 20H and 201, the tab 3184 may extend outwardly from an edge of the non-patient-facing removable layer 3180 substantially opposite one or more slits 3182. For example, the tab 3184 may be located diametrically opposite one or more slits 3182. In other forms, such as the form shown in Fig. 20C, the slit 3182 may be located azimuthally immediately adjacent to tab 3184.4.3.2 Plenum chamber

[0249] The plenum chamber 3200 of certain forms of the technology is configured to receive the flow of breathable gas at the therapeutic pressure for breathing by the patient from the air circuit 4170. The plenum chamber may be formed to be pressurisable to a therapeutic pressure of at least 6 cm FEO above ambient air pressure, and up to pressures of around 20 cmFEO or 30 cmFEO in certain forms.

[0250] In one form, the plenum chamber 3200 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. The complementary shape of the perimeter of the plenum chamber 3200 may be configured to facilitate correct positioning of the patient interface 3000 against the patient’s face in use.

[0251] Alternatively, in certain forms, the plenum chamber 3200 may be shaped in a customised way to an individual patient. Alternatively, the plenum chamber 3200 of a patient interface 3000 may be selected from one of a plurality of possibleforms of plenum chamber 3200, with the appropriate plenum chamber for an individual patient being selected as being most suitable for them.

[0252] In use, a marginal edge of the plenum chamber 3200 is positioned in close proximity to an adjacent surface of the face. Actual contact with the face may be provided by the seal-forming structure 3100. The seal-forming structure 3100 may extend in use about the entire perimeter of the plenum chamber 3200.

[0253] The plenum chamber 3200 may include at least two openings. One opening, which may be formed in a patient-facing, or posterior, side of the plenum chamber 3200, allows pressurised gas to flow from the internal volume of the plenum chamber 3200 to the patient’s airways through the seal-forming structure 3100. This opening may also allow exhaled gas from the patient to flow into the plenum chamber 3200. Another opening, which may be referred to as the plenum chamber inlet port 3202, is configured to allow the flow of breathable gas from the air circuit 4170 into the plenum chamber 3200. In certain forms, the plenum chamber inlet port 3202 may be disposed on a side of the plenum chamber 3200 facing away from the patient in use, i.e. an anterior side of the plenum chamber 3200. In other forms, the patient interface may comprise one or more plenum chamber inlet ports 3202 disposed on lateral sides (e.g. left and right sides) of the plenum chamber 3200.

[0254] In certain forms, for example in the forms shown in Figs. 9, 10, 12-16, 18A and 19, the plenum chamber 3200 may be configured such that the opening in the patient-facing side of the plenum chamber 3200 is sized and shaped to cover both the patient’s nares when the patient interface 3000 is in use. In these forms, the size and shape of the opening may approximately match, and be positioned adjacent in use, an area of the underside of the patient’s nose that is made up of the patient’s nares and the patient’s columella (see Fig. 2F). The opening may be formed by a rim 3210 on the posterior side of the plenum chamber 3200 and the plenum chamber 3200 may be configured so that, in use, the rim 3210 is positioned adjacent and anterior to lateral, posterior and anterior edges of the patient’s nares.

[0255] The posterior side of the plenum chamber 3200 may be shaped to be complementary to the shape of the underside of the patient’s nose, against which the plenum chamber 3200 may be positioned in use. In the forms shown in Figs. 9, 10, 12-16, 18A and 19, the posterior side of the plenum chamber 3200 may be formed from the rim 3210 around the opening on the patient-facing side of the plenum chamber 3200. In certain examples, the posterior side of the plenum chamber 3200 may lie on a saddle-shaped surface, where in this context “saddle-shaped” refers to ageometrical surface in which lines on the surface are convex in one direction and concave in another direction, orthogonal to the first direction. More particularly, the posterior side of the plenum chamber 3200 may be concave in the lateral direction relative to the patient’s face so that the patient’s columella extends into the trough of the concavity, as shown in Fig. 16. The posterior side of the plenum chamber 3200 may be convex in the anterior-posterior direction so that the peaks of the convexity extend towards lateral edges of the patient’s nares, again as shown in Fig. 16.

[0256] When the seal-forming structure 3100 is assembled with the plenum chamber 3200, the seal-forming structure 3100, which may be formed from a flexible material, may be caused to deform to a shape that is similar to the shape of the plenum chamber 3200. As illustrated, for example in Figs. 12 to 16 and 19, the sealforming structure 3100 may, prior to being brought into sealing contact with the patient’s face, have a saddle-shaped patient-facing surface.

[0257] In certain forms of the present technology, the plenum chamber 3200 is 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.

[0258] In some forms, the plenum chamber 3200 is constructed from a rigid material such as polycarbonate. The rigid material may provide support to the sealforming structure.

[0259] In some forms, the plenum chamber 3200 is constructed from a flexible material (e.g., constructed from a soft, flexible, resilient material like silicone, textile, foam, etc.). For example, in examples then may be formed from a material which has a Young's modulus of 0.4 GPa or lower, for example foam. In some forms of the technology the plenum chamber 3200 may be made from a material having Young's modulus of 0.1 GPa or lower, for example rubber. In other forms of the technology the plenum chamber 3200 may be made from a material having a Young's modulus of 0.7MPa or less, for example between 0.7MPa and 0.3MPa. An example of such a material is silicone.

[0260] In some forms, the plenum chamber 3200 and the seal-forming structure 3100 are formed from a single homogeneous piece of material, for example silicone or TPE.4.3.3 Connection of Plenum Chamber and Seal-Forming Structure

[0261] The plenum chamber 3200 may be connected to the seal-forming structure 3100. In certain forms, the plenum chamber 3200 is directly connected tothe seal-forming structure 3100. For example, the plenum chamber 3200 may be connected to the seal-forming structure 3100 through a mechanical joint, with adhesive or the plenum chamber 3200 and the seal-forming structure 3100 may be integrally formed. In other forms, the plenum chamber 3200 may be indirectly connected to the seal-forming structure 3100, for example via another component.4.3.3.1 Connecting portion

[0262] In certain forms of the technology, for example as illustrated in Figs. 12- 15, the patient interface 3000 comprises a connecting portion 3160 which is positioned between the plenum chamber 3200 and the seal-forming structure 3100. The connecting portion 3160 in these forms is formed with a thickness that is substantially thinner than adjacent regions of the plenum chamber 3200 and the sealforming structure 3100. The relative thicknesses may be configured such that the connection portion 3160 allows flexibility of movement of the patient interface 3000 in that it allows relative displacement between the seal-forming structure 3100 and the plenum chamber 3200.

[0263] In certain forms, the connecting portion 3160 may be sufficiently thin that it is substantially flexible to allow the relative displacement between the sealforming structure 3100 and the plenum chamber 3200.

[0264] In other forms, the connecting portion 3160 may be formed in a structure that enables the seal-forming structure 3100 to move relative to the plenum chamber 3200, for example the connecting portion 3160 may comprise a plurality of folds. For instance, the connecting portion 3160 may have a concertina-like configuration.

[0265] The connecting portion 3160 may permit some displacement between the seal-forming structure 3100 and the plenum chamber 3200 as a translation, rotation or both.

[0266] If a force is applied to the air circuit 4170, the force may be transferred, via the plenum chamber 3200, to the seal-forming structure 3100. As the sealforming structure 3100 is configured to adhere to the patient 1000 through an adhesive surface, such a transfer of forces directly to the seal-forming structure 3100 may cause the patient’s skin to be pulled, thereby causing discomfort to the patient 1000 or removal of the seal-forming structure 3100. The connecting portion 3160 therefore allows for a greater amount of movement of the air circuit 4170 without these effects occurring.

[0267] In certain forms, for example the forms shown in Figs. 12-15, the connecting portion 3160 extends a substantial part of the way around the opening formed in the patient-facing side of the plenum chamber 3200, for example the connecting portion 3160 may extend all the way around this opening. The connection portion 3160 may therefore have the shape of a ring around the patient-proximal end of the plenum chamber 3200. In other forms, the connection portion 3160 may extend only part of the way around the ring-shaped join between the plenum chamber 3200 and the seal-forming structure 3100. In some forms, the connection portion 3160 may comprise multiple regions having thicknesses that are substantially thinner than adjacent regions of the plenum chamber 3200 and the seal-forming structure 3100. Each of the regions may be separated from other regions by thicker regions. In this way, the nature of the flexibility between the plenum chamber 3200 and the sealforming structure 3100 may be controlled.4.3.3.2 Adhesive Connection

[0268] In some forms, the plenum chamber 3200 may be connected to the sealforming structure 3100 with adhesive. Example of such forms are illustrated in Figs. 15 to 19, 21 and 22. It has already been described above that an adhesive surface on a non-patient-facing side of the seal-forming structure 3100 may adhere to a patientfacing side of the plenum chamber 3200, for example rim 3210. Alternatively, the flange 3105, which may be considered as part of the seal-forming structure 3100, may be integrally formed with the plenum chamber 3200 and other parts of the sealforming structure 3100 may be adhered to the flange 3105 as described earlier.4.3.4 Positioning and stabilising structure

[0269] 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 engage the patient’s head in order to hold the patient interface 3000 in a sealing position.

[0270] 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.

[0271] 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.

[0272] 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.

[0273] 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 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. 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.

[0274] As has already been explained, in certain forms of the technology, the patient interface 3000 comprises a seal-forming structure 3100 that is configured to adhere to the patient’s face so as to form a seal and to maintain the patient interface 3000 in position on the patient’s face. In such forms, the seal-forming structure 3100 may be considered to additionally function as the positioning and stabilising structure 3300 through the action of the adhesive.4.3.5 Vent

[0275] In certain forms of the technology, the patient interface 3000 comprises a vent 3400 constructed and arranged to allow for the washout of exhaled gases, e.g. carbon dioxide. The vent 3400 may be implemented through a vent structure, which may be formed or provided in any one or more components of the patient interface 3000.

[0276] 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.

[0277] One form of vent 3400 in accordance with the present technology comprises a plurality of holes, for example, about 5 to about 80 holes, or about 10 to about 40 holes, or about 20 to about 25 holes.

[0278] In certain forms of the technology, for example as shown in Figs. 5 and 9, the vent 3400 may be located in the plenum chamber 3200.

[0279] Alternatively, the vent 3400 may be located in the air circuit 4170 that delivers the flow of breathable gas from the RPT device 4000 to the plenum chamber 3200, for example in a part of the air circuit 4170 located proximate to the plenum chamber 3200.4.3.5.1 Ports

[0280] In certain forms 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 certain forms 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.4.3.5 2 Breath-To-Atmosphere Vent

[0281] In certain forms of the technology, the patient interface 3000 may include a vent 3400 configured to be able to adopt at least two configurations. In one configuration, which may be termed an open configuration, the vent 3400 allows the patient to inhale and exhale through the vent 3400 without significant impedance, or with a level of impedance that is largely unnoticeable by the patient. In another configuration, which may be termed a closed configuration, the vent 3400 is more occluded than in the open configuration. In some forms, in the closed configuration, the vent 3400 allows the washout of exhaled gases from an interior of the plenum chamber 3200 to ambient whilst substantially maintaining the pressure within the plenum chamber as positive with respect to ambient. In other forms, in the closed configuration, the vent may substantially block all washout of gases through the vent, and instead exhaled gases exhaust through a separate vent structure. Such a vent 3400 may be referred to as a “breathe-to-atmosphere” vent (BTA vent).

[0282] Whether the BTA vent adopts the open or closed configuration may be based on the pressure of the supply of breathable gas provided from the RPT device 4000 to the patient interface 3000. When no breathable gas is supplied, or when the flow of breathable gas is supplied at a pressure below a certain threshold, for example below a therapeutic pressure level such as 6 cmkhO, the BTA vent may beconfigured to adopt the open configuration. When the flow of breathable gas is supplied at a pressure above a certain threshold, for example above a therapeutic pressure level such as 6 cmFLO, the BTA vent may be configured to adopt the closed configuration.

[0283] A further explanation of a patient interface system comprising a vent that may be considered to act in the manner of a BTA vent, as described above, is provided in PCT Application No. PCT / US2012 / 055148, the contents of which are hereby incorporated by reference.

[0284] In one application, a BTA vent may be used in a patient interface system in which the BTA vent is configured to adopt the open configuration when the patient first dons the patient interface 3000 and while the patient is detected as being awake by the RPT device 4000. In this configuration, the RPT device may not supply a flow of breathable gas, or may be configured to provide a small flow of breathable gas to help flush out exhaled CO2 from the plenum chamber 3200. Once the RPT device 4000 detects that the patient has gone to sleep, the flow of breathable gas may be supplied at a therapeutic pressure, which causes the BTA vent to adopt the closed configuration.4.3.5.2.1 Anti-asphyxia valve

[0285] One form of BTA vent is an anti-asphyxia valve (AAV) which is conventionally used in patient interfaces which cover both the nose and mouth as a measure to mitigate the risk of asphyxiation. The AAV ensures ventilation to the airways of the patient 1000 in case of disruption of the supply of breathable gas to the plenum chamber 3200 and / or the airways of the patient 1000. In certain forms of the present technology, a patient interface 3000 may comprise a conventional design of AAV acting in use as a BTA vent, as described above.

[0286] For example, in the form of the technology illustrated in Fig. 8, the patient interface 3000 comprises a vent 3400 that, in use acts as a BTA vent in the manner described above. The BTA vent may be in the form of an anti-asphyxia valve 3402. In the illustrated form of the technology, the anti-asphyxia valve 3402 is located on or proximate an end of the air circuit 4170 that connects to the inlet port 3202 of the plenum chamber 3200. In other forms, the AAV may be located in another location, for example in the plenum chamber 3200, or in a tube connected between the air circuit 4170 and the plenum chamber 3200.

[0287] The anti-asphyxia valve 3402 may comprise a flap which, when the valve 3402 is in the closed configuration, is configured to cover an opening in a wall of the air circuit 4170 and to prevent or limit leakage of gas contained in the plenum chamber 3200 in use. When the valve is in the open configuration, for example in case of a disruption or reduction in the flow of the breathable gas to the plenum chamber 3200, or if the pressure of the breathable gas supplied by the RPT device 4000 has not yet ramped up (e.g. if the patient is detected as still being awake), the flap is in a position where the opening is less occluded to allow the patient 1000 to breathe directly to and from the ambient atmosphere.4.3.5.3 Expiratory Resistance Valve

[0288] In certain forms of the technology, positive pressure within the plenum chamber 3200 may be created in a manner other than through the supply of air into the plenum chamber 3200 from a RPT device 4000. For example, in one form of respiratory therapy system 2000, positive pressure is created in the plenum chamber 3200 from the flow of gases exhaled by the patient. Such a system may be referred to as an expiratory positive airway pressure (EPAP) system. EPAP systems according to certain forms of the technology may not comprise a RPT device or an air circuit as described herein. Instead, the EPAP system may comprise a vent that is configured to create and maintain the therapeutic pressure in the plenum chamber from the flow of gases exhaled by the patient.4.4 AIR CIRCUIT

[0289] In one form, the patient interface 3000 may be comprised as part of a patient interface system 5000 which also includes an air circuit 4170. The air circuit 4170 is configured to convey breathable gas to the patient interface 3000 for delivery to the airways of the patient 1000. For example, the air circuit 4170 of the form of the technology shown in Fig. 1 conveys the breathable gas from the RPT device 4000 to the plenum chamber 3200.

[0290] A first end of the air circuit 4170 may be connected to the plenum chamber inlet port 3202. A second end of the air circuit 4170, which may be opposite to the first end, may be connected to an RPT device 4000.

[0291] In exemplary forms of the technology, the air circuit 4170 is flexible.

[0292] In certain forms, the geometric dimensions of the air circuit 4170 may depend on the flow parameters of the breathable gas supplied to the patient from the RPT device 4000. For instance, the diameter of the air circuit 4170 may be relativelysmall in the case of an RPT device 4000 configured to provide a supply of breathable gas at relatively low pressures (e.g. 2 to 6 cmFhO), i.e. low pressure therapy. The diameter of the air circuit 4170 may be relatively larger for use with RPT devices 4000 configured to supply breathable gas at higher pressures (e.g. 6 to 20 cmFhO).4.4.1 Positioning of air circuit

[0293] The patient interfaces 3000 described in relation to various forms of the technology herein may be accommodate the positioning of air circuits 4170 in various arrangements with respect to the patient.

[0294] In certain forms, the air circuit 4170 may be configured to be routed to the patient interface 3000 from substantially above a transverse plane which is configured to pass through the patient’s nasal and / or mouth regions, e.g. the Frankfort horizontal (see Fig. 2E). In such a form, the patient interface 3000 may comprise a positioning structure configured to hold part of the air circuit 4170 in relation to the patient’s head in the desired position, for example the part of the air circuit 4170 may be held in a position superior to the patient’s otobasion superior. For example, the positioning structure may comprise one or more straps configured to be worn on the patient’s head and to engage the air circuit 4170. In one form, the air circuit 4170 may be configured to pass over the top and / or the back of a patient’s head. Alternatively, or additionally, the air circuit 4170 may be configured to pass behind and / or close to the back of a patient’s neck when the patient interface system 5000 is in use.

[0295] In another form, the air circuit 4170 may be configured to reach the patient interface 3000 from substantially below a transverse plane which is configured to pass through the patient’s nasal and / or mouth regions, e.g. the Frankfort horizontal. Such an arrangement is shown in Figs. 3A, 4A, 4B and 10F, for example. In this form, the patient interface 3000 may not need any positioning structure to secure the air circuit 4170 in place.

[0296] In one form, the air circuit 4170 may be routed around and / or proximal to one or both ears of the patient 1000. For instance, the air circuit 4170 may branch into two conduits before the end of the air circuit 4170 that connects to the patient interface 3000. Each of the conduits may be configured to be able to be passed behind respective ears of the patient 1000 in use.4.5 RPT DEVICE

[0297] 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 whole or 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.

[0298] In certain forms, the RPT device 4000 may be configured to deliver a flow of air to the patient interface 3000 at a positive pressure with respect to ambient. The RPT device 4000 may be configured to deliver air at a therapeutic pressure, for example at least 6 cmEbO with respect to ambient. Conventional RPT devices 4000 may be used for this purpose.

[0299] In other forms, the RPT device 4000 may be configured to deliver a flow or air to the patient interface 3000 at a lower pressure (but still at a positive pressure relative to ambient), for example 2 to 6 cmFEO with respect to ambient. Respiratory therapy systems incorporating RPT devices 4000 delivering a flow of air at such pressures may be useful for providing low level therapy. For example, such systems may be useful for treating, or ameliorating snoring, or other mild respiratory conditions. Compared to an RPT device that is able to deliver air at higher pressures, for example RPT devices that may be suitable for treating obstructive sleep apnea, such systems may be cheaper to manufacture, use less power and be more compact in size.

[0300] Fig. 1 illustrates a respiratory therapy system 2000 incorporating a RPT device 4000 of the type just described. In the form shown in Fig. 1, breathable gas is conveyed to the patient interface 3000 RPT device 4000 which is compact in size and may therefore be portable, i.e. able to be carried by the patient during use, e.g. mounted on the patient’s person or clothing. For example, the RPT device 4000 may be strapped around the patient’s neck or arm, or carried in a pocket, in use.

[0301] Breathable gas from the RPT device 4000 may be conveyed to the patient interface 3000 through an air circuit 4170. The inlet port 3202 of the plenum chamber 3200 may be connected to an end of the air circuit 4170 with the other end of the air circuit 4170 being connected to the RPT device. Since the flow rate and / or pressure of the supply of air may be lower than with a conventional RPT device 4000 (e.g. a CPAP device), the air circuit 4170 may have a reduced diameter compared to conventional air circuits. For example, in certain forms, the air circuit 4170 may havea diameter in the range 5-15 mm, for example 10 mm. A smaller diameter tube provides more impedance to the flow of air than a larger diameter tube but this is acceptable if the flow rate and / or pressure to be delivered is also low. A smaller diameter tube may be desirable as being less bulky and obtrusive, easier to store or package, and cheaper to manufacture.4.6 GLOSSARY

[0302] 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.4.6.1 General

[0303] 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.

[0304] 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.

[0305] 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.

[0306] In another example, ambient pressure may be the pressure immediately surrounding or external to the body.

[0307] 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.

[0308] 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 (Sleep Disordered Breathing) events.

[0309] 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 theairways 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.

[0310] 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’.

[0311] 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.

[0312] 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.

[0313] 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.

[0314] 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.

[0315] 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.

[0316] 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.

[0317] 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”.

[0318] Medical Oxygen: Medical oxygen is defined as oxygen enriched air with an oxygen concentration of 80% or greater.

[0319] Patient: A person, whether or not they are suffering from a respiratory condition.

[0320] Pressure: Force per unit area. Pressure may be expressed in a range of units, including cmFLO, g-f / cm2 and hectopascal. 1 cm FLO is equal to 1 g-f / cm2 and 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 cm FLO.

[0321] 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.

[0322] 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.

[0323] Ventilator: A mechanical device that provides pressure support to a patient to perform some or all of the work of breathing.4.6.1.1 Materials

[0324] 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 molded 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.

[0325] Polycarbonate: a thermoplastic polymer of Bisphenol-A Carbonate.4.6.1.2 Mechanical properties

[0326] Resilience: Ability of a material to absorb energy when deformed elastically and to release the energy upon unloading.

[0327] Resilient: Will release substantially all of the energy when unloaded. Includes e.g. certain silicones, and thermoplastic elastomers.

[0328] 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.

[0329] 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.

[0330] 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.

[0331] 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.

[0332] 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.4.6.2 Anatomy4.6.2.1 Anatomy of the face

[0333] Ala: the external outer wall or “wing” of each nostril (plural: alar)

[0334] Alare: The most lateral point on the nasal ala.

[0335] 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.

[0336] Auricle: The whole external visible part of the ear.

[0337] (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.

[0338] (nose) Cartilaginous framework: The cartilaginous framework of the nose comprises the septal, lateral, major and minor cartilages.

[0339] Columella: the strip of skin that separates the nares and which runs from the pronasale to the upper lip.

[0340] 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.

[0341] Frankfort horizontal plane: A line extending from the most inferior point of the orbital margin to the left tragion. The tragion is the deepest point in the notch superior to the tragus of the auricle.

[0342] Glabella: Located on the soft tissue, the most prominent point in the midsagittal plane of the forehead.

[0343] 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.

[0344] Lip, lower (labrale inferius):

[0345] Lip, upper (labrale superius):

[0346] 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.

[0347] 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.

[0348] 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.

[0349] Naso-labial angle: The angle between the columella and the upper lip, while intersecting subnasale.

[0350] Otobasion inferior: The lowest point of attachment of the auricle to the skin of the face.

[0351] Otobasion superior: The highest point of attachment of the auricle to the skin of the face.

[0352] 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.

[0353] Philtrum: the midline groove that runs from lower border of the nasal septum to the top of the lip in the upper lip region.

[0354] Pogonion: Located on the soft tissue, the most anterior midpoint of the chin.

[0355] Ridge (nasal): The nasal ridge is the midline prominence of the nose, extending from the Sellion to the Pronasale.

[0356] 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.

[0357] Sellion: Located on the soft tissue, the most concave point overlying the area of the frontonasal suture.

[0358] Septal cartilage (nasal): The nasal septal cartilage forms part of the septum and divides the front part of the nasal cavity.

[0359] Subalare: The point at the lower margin of the alar base, where the alar base joins with the skin of the superior (upper) lip.

[0360] Subnasal point: Located on the soft tissue, the point at which the columella merges with the upper lip in the midsagittal plane.

[0361] Supramenton: The point of greatest concavity in the midline of the lower lip between labrale inferius and soft tissue pogonion

[0362] Anatomy of the skull

[0363] Frontal bone: The frontal bone includes a large vertical portion, the squama frontalis, corresponding to the region known as the forehead.

[0364] Mandible: The mandible forms the lower jaw. The mental protuberance is the bony protuberance of the jaw that forms the chin.

[0365] 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.

[0366] 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.

[0367] 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.

[0368] 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.

[0369] Orbit: The bony cavity in the skull to contain the eyeball.

[0370] Parietal bones: The parietal bones are the bones that, when joined together, form the roof and sides of the cranium.

[0371] 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.

[0372] 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.4.6.3 Patient interface

[0373] 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.

[0374] 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.

[0375] 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.

[0376] 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.

[0377] 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 ofspace, the volume having air therein pressurised above atmospheric pressure in use. A shell may form part of the walls of a mask plenum chamber.

[0378] 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.

[0379] 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.

[0380] 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.

[0381] 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.

[0382] Swivel (noun): A subassembly of components configured to rotate about a common axis, preferably independently, preferably under low torque. In one form, the swivel may be constructed to rotate through an angle of at least 360 degrees. In another form, the swivel may be constructed to rotate through an angle less than 360 degrees. When used in the context of an air delivery conduit, the sub-assembly of components preferably comprises a matched pair of cylindrical conduits. There may be little or no leak flow of air from the swivel in use.

[0383] Tie (noun): A structure designed to resist tension.

[0384] 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.4.7 OTHER REMARKS

[0385] 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.

[0386] 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.

[0387] 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.

[0388] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this technology belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present technology, a limited number of the exemplary methods and materials are described herein.

[0389] 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.

[0390] 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.

[0391] 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 ofpublication provided may be different from the actual publication dates, which may need to be independently confirmed.

[0392] 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.

[0393] 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.

[0394] Although the technology herein has been described with reference to particular examples, it is to be understood that these examples are merely illustrative of the principles and applications of the technology. In some instances, the terminology and symbols may imply specific details that are not required to practice the technology. For example, although the terms "first" and "second" may be used, unless otherwise specified, they are not intended to indicate any order but may be utilised to distinguish between distinct elements. Furthermore, although process steps in the methodologies may be described or illustrated in an order, such an ordering is not required. Those skilled in the art will recognize that such ordering may be modified and / or aspects thereof may be conducted concurrently or even synchronously.

[0395] 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 patient interface for use in delivering breathable gas to a patient, the patient interface comprising: a plenum chamber pressurisable to a therapeutic pressure of at least 6 cmfLO above ambient air pressure, said plenum chamber including a plenum chamber inlet port configured to receive a flow of breathable gas at the therapeutic pressure for breathing by the patient; a seal-forming structure provided to the plenum chamber, wherein the sealforming structure is configured 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 an opening therein such that the flow of breathable gas is delivered to at least an entrance to the patient’s nares, the seal -forming structure being configured to maintain said therapeutic pressure in the plenum chamber throughout the patient’s respiratory cycle in use, wherein the seal-forming structure comprises at least one adhesive surface configured in use to adhere to a region of the patient’s face to form the seal; a vent structure to allow a continuous flow of gases exhaled by the patient from an interior of the plenum chamber to ambient, said vent structure being configured to maintain the therapeutic pressure in the plenum chamber in use; and at least one shape retainer removably mounted to the seal-forming structure and configured to promote retention of the shape of the seal-forming structure before the seal-forming structure is made to adhere to the patient’s face, wherein the at least one shape retainer comprises a loop which extends around at least a substantial part of an outer perimeter of the seal-forming structure.

2. The patient interface as claimed in claim 1, wherein the at least one shape retainer is removably mounted to a non-patient-facing side of the seal-forming structure.

3. The patient interface as claimed in any one of the preceding claims, wherein the at least one shape retainer comprises a radially inner edge and the at least one shape retainer is configured such that, when the at least one shape retainer ismounted to the seal-forming structure, the radially inner edge is spaced from the opening.

4. The patient interface as claimed in any one of the preceding claims, wherein the at least one shape retainer comprises a first end and a second end separated by a gap-5. The patient interface as claimed in any one of the preceding claims, wherein the at least one shape retainer comprises a tab configured to be grasped by a user for removing the at least one shape retainer from the seal-forming structure.

6. The patient interface as claimed in claim 5, wherein the tab extends radially inwards from the loop towards the opening.

7. The patient interface as claimed in claim 5 or 6, wherein the tab extends from an outer lateral region of the loop in a lateral-medial direction.

8. The patient interface as claimed in any one of claims 5 to 7, wherein the tab is a first tab and the at least one shape retainer comprises a second tab configured to be grasped by a user for removing the at least one shape retainer from the seal-forming structure, wherein the first tab is located on one side of the patient’s medial plane in use, and wherein the second tab is located on the other side of the patient’s medial plane in use.

9. A patient interface for use in delivering breathable gas to a patient, the patient interface comprising: a plenum chamber pressurisable to a therapeutic pressure of at least 6 cmfTO above ambient air pressure, said plenum chamber including a plenum chamber inlet port configured to receive a flow of breathable gas at the therapeutic pressure for breathing by the patient; a seal-forming structure provided to the plenum chamber, wherein the sealforming structure is configured 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 an opening therein such that the flow of breathable gas is delivered to at least an entrance to the patient’s nares, the seal -forming structure being configured tomaintain said therapeutic pressure in the plenum chamber throughout the patient’s respiratory cycle in use; and a vent structure to allow a continuous flow of gases exhaled by the patient from an interior of the plenum chamber to ambient, said vent structure being configured to maintain the therapeutic pressure in the plenum chamber in use, wherein the seal-forming structure comprises at least one adhesive surface configured in use to adhere to a region of the patient’s face to form the seal, and wherein the seal-forming structure is configured with one or more notches formed in an edge of a lateral region of the seal-forming structure.

10. The patient interface as claimed in claim 9, wherein at least one of the one or more notches is formed in a region of the seal-forming structure that is configured to adhere to the patient’s nose in use.

11. The patient interface as claimed in claim 9 or 10, wherein at least one of the one or more notches is formed in a region of the seal-forming structure that is configured to adhere to a nasal ala of the patient in use.

12. The patient interface as claimed in any one of claims 9 to 11, wherein at least one of the one or more notches is formed in a region of the seal-forming structure that is configured to adhere to the patient’s cheek in use.

13. The patient interface as claimed in claim 11 or 12, wherein at least one of the one or more notches is formed between adjacent regions of the seal-forming structure that are respectively configured to adhere to the patient’s face either side of a junction between the patient’s nasal ala and the patient’s cheek in use.

14. The patient interface as claimed in any one of claims 9 to 13, wherein at least one of the one or more notches is formed in a region of the seal-forming structure that is configured to adhere to the patient’s lip superior region in use.

15. The patient interface as claimed in any one of claims 9 to 14, wherein at least one of the one or more notches is formed in a region of the seal-forming structure that is configured to adhere to a patient’s nasolabial sulcus region in use.

16. The patient interface as claimed in any one of claims 9 to 15, wherein the seal-forming structure is configured so that at least one of the one or more notches extends in use substantially laterally inwardly towards the patient’s medial plane from a lateral edge of the seal-forming structure.

17. The patient interface as claimed in any one of claims 9 to 16, wherein at least one of the one or more notches is substantially slit-shaped.

18. The patient interface as claimed in any one of claims 9 to 17, wherein the one or more notches comprises a first notch and a second notch, wherein the first notch is formed in a region of the seal-forming structure that is configured to be located on one side of the medial plane during use, and wherein the second notch is formed in a region of the seal-forming structure that is configured to be located on the other side of the medial plane during use.

19. A patient interface for use in delivering breathable gas to a patient, the patient interface comprising: a plenum chamber pressurisable to a therapeutic pressure of at least 6 cmtkO above ambient air pressure, said plenum chamber including a plenum chamber inlet port configured to receive a flow of breathable gas at the therapeutic pressure for breathing by the patient; a seal-forming structure provided to the plenum chamber, wherein the sealforming structure is configured 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 an opening therein such that the flow of breathable gas is delivered to at least an entrance to the patient’s nares, the seal -forming structure being configured to maintain said therapeutic pressure in the plenum chamber throughout the patient’s respiratory cycle in use; and a vent structure to allow a continuous flow of gases exhaled by the patient from an interior of the plenum chamber to ambient, said vent structure being configured to maintain the therapeutic pressure in the plenum chamber in use, wherein the seal-forming structure comprises at least one adhesive surface configured in use to adhere to a region of the patient’s face to form the seal, andwherein the seal-forming structure is configured with one or more notches formed in an edge of the seal-forming structure which is positioned substantially inferior to the opening during use.

20. The patient interface as claimed in claim 19, wherein at least one of the one or more notches is formed in a region of the seal-forming structure that is configured to adhere to the patient’s subnasale in use.

21. The patient interface as claimed in any one of claims 19 to 20, wherein at least one of the one or more notches is formed in a region of the seal-forming structure that is configured to adhere to the patient’s lip superior region.

22. The patient interface as claimed in any one of claims 19 to 21, wherein at least one of the one or more notches is formed in a region of the seal-forming structure that is configured to adhere to a region of the patient’s face positioned on or proximate the patient’s medial plane in use.

23. The patient interface as claimed in any one of claims 19 to 22, wherein at least one of the one or more notches is formed in a region of the seal-forming structure that is configured to adhere to a region of the patient’s face positioned lateral to the patient’s medial plane in use.

24. A patient interface for use in delivering breathable gas to a patient, the patient interface comprising: a plenum chamber pressurisable to a therapeutic pressure of at least 6 cmfTC) above ambient air pressure, said plenum chamber including a plenum chamber inlet port configured to receive a flow of breathable gas at the therapeutic pressure for breathing by the patient; a seal-forming structure configured 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 an opening therein such that the flow of breathable gas is delivered to at least an entrance to the patient’s nares, the seal -forming structure being configured to maintain said therapeutic pressure in the plenum chamber throughout the patient’s respiratory cycle in use, wherein the seal-forming structure comprises atleast one adhesive surface configured in use to adhere to a region of the patient’s face to form the seal; a connecting portion positioned between the seal-forming structure and the plenum chamber, wherein the connecting portion is formed with a thickness that is substantially thinner than adjacent regions of the plenum chamber and the sealforming structure to allow relative displacement between the seal-forming structure and the plenum chamber; and a vent structure to allow a continuous flow of gases exhaled by the patient from an interior of the plenum chamber to ambient, said vent structure being configured to maintain the therapeutic pressure in the plenum chamber in use.

25. The patient interface as claimed in claim 24, wherein the connecting portion extends around an opening formed in a patient-facing side of the plenum chamber.

26. A patient interface for use in delivering breathable gas to a patient, the patient interface comprising: a plenum chamber pressurisable to a therapeutic pressure of at least 6 cmfTO above ambient air pressure, said plenum chamber including a plenum chamber inlet port configured to receive a flow of breathable gas at the therapeutic pressure for breathing by the patient; a seal-forming structure, wherein the seal-forming structure is configured 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 an opening therein such that the flow of breathable gas is delivered to at least an entrance to the patient’s nares, the sealforming structure being configured to maintain said therapeutic pressure in the plenum chamber throughout the patient’s respiratory cycle in use; and a vent structure to allow a continuous flow of gases exhaled by the patient from an interior of the plenum chamber to ambient, said vent structure being configured to maintain the therapeutic pressure in the plenum chamber in use; and wherein the seal-forming structure comprises: at least one patient-facing adhesive surface configured in use to adhere to a region of the patient’s face to form the seal; at least one non-patient-facing adhesive surface formed around the opening and configured to adhere to a patient-facing side of the plenum chamber; anda non-patient-facing removable layer positioned over the non-patient- facing adhesive surface and configured to be removed prior to adhering the plenum chamber to the seal-forming structure, wherein in the non-patient- facing removable layer is formed a slit extending from an edge of the non- patient-facing removable layer.

27. The patient interface as claimed in claim 26, wherein the seal-forming structure further comprises a patient-facing removable layer positioned over the patient-facing adhesive surface and configured to be removed prior to adhering the seal-forming structure to the patient’s face.

28. The patient interface as claimed in any one of claims 26 to 27, wherein the non-patient-facing removable layer is formed with a hole therein, wherein the hole substantially aligns with the opening when the non-patient-facing removable layer is positioned over the non-patient-facing adhesive surface.

29. The patient interface as claimed in claim 28, wherein the slit extends from a radially outer edge of the non-patient-facing removable layer to a radially inner edge of the non-patient-facing removable layer.

30. The patient interface as claimed in any one of claims 26 to 29, wherein the slit extends at least partially in an azimuthal direction around the non-patient-facing removable layer.

31. The patient interface as claimed in any one of claims 26 to 30, wherein the non-patient-facing removable layer comprises a tab configured to be grasped by a user for removing the non-patient-facing removable layer from the seal-forming structure.

32. The patient interface as claimed in claim 31, wherein the tab extends outwardly from an edge of the non-patient-facing removable layer substantially opposite the slit.

33. The patient interface as claimed in any one of claims 26 to 32, wherein the slit is a first slit and in the non-patient-facing removable layer is formed a second slitextending from an edge of the non-patient-facing removable layer, wherein the second slit extends from a radially outer edge of the non-patient-facing removable layer to a radially inner edge of the non-patient-facing removable layer.

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