Flow disruptors for a patient interface

Abstract

Disclosed are flow disruptors designed to reduce the jetting effects of airflow in patient interfaces designed for the treatment of respiratory disorders. In some examples the flow disruptor may be formed as part of the shell, seal-forming structure, or connection port of a patient interface, and in other examples the flow disruptor may be attached to a clip within the patient interface.

Description

FLOW DISRUPTORS FOR A PATIENT INTERFACE1 CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Australian Patent Application No. 2024902533, filed 14 August 2024, and Australian Patent Application No. 2024904215, filed 19 December 2024, which are hereby incorporated herein in their entirety.2 BACKGROUND OF THE TECHNOLOGY2.1 FIELD OF THE TECHNOLOGY

[0002] 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.2.2 DESCRIPTION OF THE RELATED ART2.2.1 Human Respiratory System and its Disorders

[0003] The respiratory system of the body facilitates gas exchange. The nose and mouth form the entrance to the airways of a patient.

[0004] 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.

[0005] A range of respiratory disorders exist. Certain disorders may be characterised by particular events, e.g. apneas, hypopneas, and hyperpneas.

[0006] Examples of respiratory disorders include Obstructive Sleep Apnea (OSA), Cheyne-Stokes Respiration (CSR), respiratory insufficiency, Obesity Hypoventilation Syndrome (OHS), Chronic Obstructive Pulmonary Disease (COPD), Neuromuscular Disease (NMD) and Chest wall disorders.

[0007] Obstructive Sleep Apnea (OSA), a form of Sleep Disordered Breathing (SDB), is characterised by events including occlusion or obstruction of the upper air passage during sleep. It results from a combination of an abnormally small upper airway and the normal loss of muscle tone in the region of the tongue, soft palate and posterior oropharyngeal wall during sleep. The condition causes the affected patient to stop breathing for periods typically of 30 to 120 seconds in duration, sometimes 200 to 300 times per night. It often causes excessive daytime somnolence, and it may cause cardiovascular disease and brain damage. The syndrome is a common disorder, particularly in middle aged overweight males, although a person affected may have no awareness of the problem, e.g. see US Patent No. 4,944,310 (Sullivan).

[0008] Cheyne-Stokes Respiration (CSR) is another form of sleep disordered breathing. CSR is a disorder of a patient's respiratory controller in which there are rhythmic alternating periods of waxing and waning ventilation known as CSR cycles. CSR is characterised by repetitive de-oxygenation and re-oxygenation of the arterial blood. It is possible that CSR is harmful because of the repetitive hypoxia. In some patients CSR is associated with repetitive arousal from sleep, which causes severe sleep disruption, increased sympathetic activity, and increased afterload, e.g. see US Patent No. 6,532,959 (Berthon- Jones).

[0009] Respiratory failure is an umbrella term for respiratory disorders in which the lungs are unable to inspire sufficient oxygen or exhale sufficient CO2 to meet the patient’s needs. Respiratory failure may encompass some or all of the following disorders.

[0010] A patient with respiratory insufficiency (a form of respiratory failure) may experience abnormal shortness of breath on exercise.

[0011] Obesity Hypoventilation Syndrome (OHS) is defined as the combination of severe obesity and awake chronic hypercapnia, in the absence of other known causes for hypoventilation. Symptoms include dyspnea, morning headache and excessive daytime sleepiness.

[0012] Chronic Obstructive Pulmonary Disease (COPD) encompasses any of a group of lower airway diseases that have certain characteristics in common. These include increased resistance to air movement, extended expiratory phase of respiration, and loss of the normal elasticity of the lung. Examples of COPD are emphysema and chronic bronchitis. COPD is caused by chronic tobacco smoking (primary risk factor),occupational exposures, air pollution and genetic factors. Symptoms include: dyspnea on exertion, chronic cough and sputum production.

[0013] Neuromuscular Disease (NMD) is a broad term that encompasses many diseases and ailments that impair the functioning of the muscles either directly via intrinsic muscle pathology, or indirectly via nerve pathology. Some NMD patients are characterised by progressive muscular impairment leading to loss of ambulation, being wheelchair-bound, swallowing difficulties, respiratory muscle weakness and, eventually, death from respiratory failure. Neuromuscular disorders can be divided into rapidly progressive and slowly progressive: (i) Rapidly progressive disorders: Characterised by muscle impairment that worsens over months and results in death within a few years (e.g. Amyotrophic lateral sclerosis (ALS) and Duchenne muscular dystrophy (DMD) in teenagers); (ii) Variable or slowly progressive disorders: Characterised by muscle impairment that worsens over years and only mildly reduces life expectancy (e.g. Limb girdle, Facioscapulohumeral and Myotonic muscular dystrophy). Symptoms of respiratory failure in NMD include: increasing generalised weakness, dysphagia, dyspnea on exertion and at rest, fatigue, sleepiness, morning headache, and difficulties with concentration and mood changes.

[0014] Chest wall disorders are a group of thoracic deformities that result in inefficient coupling between the respiratory muscles and the thoracic cage. The disorders are usually characterised by a restrictive defect and share the potential of long term hypercapnic respiratory failure. Scoliosis and / or kyphoscoliosis may cause severe respiratory failure. Symptoms of respiratory failure include: dyspnea on exertion, peripheral oedema, orthopnea, repeated chest infections, morning headaches, fatigue, poor sleep quality and loss of appetite.

[0015] A range of therapies have been used to treat or ameliorate such conditions. Furthermore, otherwise healthy individuals may take advantage of such therapies to prevent respiratory disorders from arising. However, these have a number of shortcomings.2.2.2 Therapies

[0016] 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.2.2.2.1 Respiratory pressure therapies

[0017] 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).

[0018] 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.

[0019] Non-invasive ventilation (NIV) provides ventilatory support to a patient through the upper airways to assist the patient breathing and / or maintain adequate oxygen levels in the body by doing some or all of the work of breathing. The ventilatory support is provided via a non-invasive patient interface. NIV has been used to treat CSR and respiratory failure, in forms such as OHS, COPD, NMD and Chest Wall disorders. In some forms, the comfort and effectiveness of these therapies may be improved.

[0020] 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.2.2.2.2 Flow therapies

[0021] Not all respiratory therapies aim to deliver a prescribed therapeutic pressure. Some respiratory therapies aim to deliver a prescribed respiratory volume, by delivering an inspiratory flow rate profile over a targeted duration, possibly superimposed on a positive baseline pressure. In other cases, the interface to the patient’s airways is ‘open’ (unsealed) and the respiratory therapy may only supplement the patient’s own spontaneous breathing with a flow of conditioned or enriched gas. In one example, High Flow therapy (HFT) is the provision of a continuous, heated, humidified flow of air to an entrance to the airway through an unsealed or open patientinterface at a “treatment flow rate” that may be held approximately constant throughout the respiratory cycle. The treatment flow rate is nominally set to exceed the patient’s peak inspiratory flow rate. HFT has been used to treat OSA, CSR, respiratory failure, COPD, and other respiratory disorders. One mechanism of action is that the high flow rate of air at the airway entrance improves ventilation efficiency by flushing, or washing out, expired CO2 from the patient’s anatomical deadspace. Hence, HFT is thus sometimes referred to as a deadspace therapy (DST). Other benefits may include the elevated warmth and humidification (possibly of benefit in secretion management) and the potential for modest elevation of airway pressures. As an alternative to constant flow rate, the treatment flow rate may follow a profile that varies over the respiratory cycle.

[0022] Another form of flow therapy is long-term oxygen therapy (LTOT) or supplemental oxygen therapy. Doctors may prescribe a continuous flow of oxygen enriched air at a specified oxygen concentration (from 21%, the oxygen fraction in ambient air, to 100%) at a specified flow rate (e.g., 1 litre per minute (LPM), 2 LPM, 3 LPM, etc.) to be delivered to the patient’s airway.2.2.3 Respiratory Therapy Systems

[0023] 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.

[0024] A respiratory therapy system may comprise a Respiratory Pressure Therapy Device (RPT device), an air circuit, a humidifier, a patient interface, an oxygen source, and data management.2.2.3.1 Patient Interface

[0025] A patient interface may be used to interface respiratory equipment to its wearer, for example by providing a flow of air to an entrance to the airways. The flow of air may be provided via a mask to the nose and / or mouth, a tube to the mouth or a tracheostomy tube to the trachea of a patient. Depending upon the therapy to be applied, the patient interface may form a seal, e.g., with a region of the patient's face, to facilitate the delivery of gas at a pressure at sufficient variance with ambient pressure to effect therapy, e.g., at a positive pressure of about 10 cmH20 relative to ambient pressure. For other forms of therapy, such as the delivery of oxygen, the patient interface may not include a seal sufficient to facilitate delivery to the airways ofa supply of gas at a positive pressure of about 10 cmH20. For flow therapies such as nasal HFT, the patient interface is configured to insufflate the nares but specifically to avoid a complete seal. One example of such a patient interface is a nasal cannula.

[0026] Certain mask systems may be functionally unsuitable for the present field. For example, purely ornamental masks may be unable to maintain a suitable pressure. Mask systems used for underwater swimming or diving may be configured to guard against ingress of water from an external higher pressure, but not to maintain air internally at a higher pressure than ambient.

[0027] 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.

[0028] Certain masks may be uncomfortable or impractical for the present technology if they require a patient to insert a portion of a mask structure in their mouth to create and maintain a seal via their lips.

[0029] 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.

[0030] Certain masks may cause some patients a feeling of claustrophobia, unease and / or may feel overly obtrusive.

[0031] 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.

[0032] Consequently, some masks suffer from being obtrusive, aesthetically undesirable, costly, poorly fitting, difficult to use, and / or uncomfortable especially when worn for long 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. This discomfort may lead to a reduction in patient compliance with therapy, especially if the mask is to be worn during sleep.

[0033] CPAP therapy is highly effective to treat certain respiratory disorders, provided patients comply with therapy. If a mask is uncomfortable, or difficult to use a patient may not comply with therapy. Since it is often recommended that a patient regularly wash their mask, if a mask is difficult to clean (e.g., difficult to assemble or disassemble), patients may not clean their mask and this may impact on patient compliance.

[0034] 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.

[0035] For these reasons, patient interfaces for delivery of CPAP during sleep form a distinct field.2.2.3.1.1 Seal-forming structure

[0036] 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.

[0037] A patient interface may be partly characterised according to the design intent of where the seal-forming structure is to engage with the face in use. In one form of patient interface, a seal-forming structure may comprise a first sub-portion to form a seal around the left naris and a second sub-portion to form a seal around the right naris. In one form of patient interface, a seal-forming structure may comprise a single element that surrounds both nares in use. Such single element may be designed to for example overlay an upper lip region and a nasal bridge region of a face. In one form of patient interface a seal-forming structure may comprise an element that surrounds a mouth region in use, e.g. by forming a seal on a lower lip region of a face. In one form of patient interface, a seal-forming structure may comprise a single element that surrounds both nares and a mouth region in use. These different types of patient interfaces may be known by a variety of names by their manufacturer including nasal masks, full-face masks, nasal pillows, nasal puffs and oro-nasal masks.

[0038] 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 sealon swimming goggles that overlays a patient’s forehead may not be appropriate to use on a patient’s nose.

[0039] 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.

[0040] One type of seal-forming structure extends around the periphery of the patient interface, and is intended to seal against the patient's face when force is applied to the patient interface with the seal-forming structure in confronting engagement with the patient's face. The seal-forming structure may include an air or fluid filled cushion, or a moulded or formed surface of a resilient seal element made of an elastomer such as a rubber. With this type of seal-forming structure, if the fit is not adequate, there will be gaps between the seal-forming structure and the face, and additional force will be required to force the patient interface against the face in order to achieve a seal.

[0041] 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.

[0042] 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.

[0043] Another form of seal-forming structure may use adhesive to achieve a seal. Some patients may find it inconvenient to constantly apply and remove an adhesive to their face.

[0044] A range of patient interface seal-forming structure technologies are disclosed in the following patent applications: WO 1998 / 004310; WO 2006 / 074513; WO 2010 / 135785.

[0045] One form of nasal pillow is found in the Adam Circuit manufactured by Puritan Bennett. Another nasal pillow, or nasal puff is the subject of US Patent 4,782,832 (Trimble et al.), assigned to Puri tan -Bennett Corporation.

[0046] ResMed Inc. has manufactured the following products that incorporate nasal pillows: SWIFTTM nasal pillows mask, SWIFTTM II nasal pillows mask, SWIFTTM LT nasal pillows mask, SWIFTTM FX nasal pillows mask and MIRAGE LIBERTYTM full-face mask. The following patent applications describe examples of nasal pillows masks: International Patent Application WO 2004 / 073778 (describing amongst other things aspects of the SWIFTTM nasal pillows mask), US Patent Application 2009 / 0044808 (describing amongst other things aspects of the SWIFTTM LT nasal pillows mask); International Patent Applications WO 2005 / 063328 and WO 2006 / 130903 (describing amongst other things aspects of the MIRAGE LIBERTYTM full-face mask); International Patent Application WO 2009 / 052560 (describing amongst other things aspects of the SWIFTTM FX nasal pillows mask).2.2.3.1.2 Positioning and Stabilising Structure

[0047] 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. Several factors may be considered when comparing different positioning and stabilising techniques. These include: how effective the technique is at maintaining the seal-forming structure in the desired position and in sealed engagement with the face during use of the patient interface; how comfortable the interface is for the patient; whether the patient feels intrusiveness and / or claustrophobia when wearing the patient interface; and aesthetic appeal.

[0048] One technique is the use of adhesives, e.g. see US Patent Application Publication No. US 2010 / 0000534. However, the use of adhesives may be uncomfortable for some.

[0049] 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.2.2.3.1.3 Pressurised Air Conduit

[0050] 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 at a location that is in front of the patient’s face when the patient interface ispositioned on the patient’s face during use. The conduit may extend from the patient interface forwards away from the patient’s face.2.2.3.1.4 Pressurised Air Conduit used for Positioning / Stabilising the Seal- Forming Structure

[0051] Another type of treatment system comprises a patient interface in which a tube that delivers pressurised air to the patient’s airways also functions as part of the headgear to position and stabilise the seal-forming portion of the patient interface at the appropriate part of the patient’s face. This type of patient interface may be referred to as having “conduit headgear” or “headgear tubing”. Such patient interfaces allow the conduit in the air circuit providing the flow of pressurised air from a respiratory pressure therapy (RPT) device to connect to the patient interface in a position other than in front of the patient’s face. One example of such a treatment system is disclosed in US Patent Publication No. US 2007 / 0246043, the contents of which are incorporated herein by reference, in which the conduit connects to a tube in the patient interface through a port positioned in use on top of the patient’s head.

[0052] It is desirable for patient interfaces incorporating headgear tubing to be comfortable for a patient to wear over a prolonged duration when the patient is asleep, form an air-tight and stable seal with the patient’s face, while also able to fit a range of patient head shapes and sizes.2.2.3.1 Respiratory Pressure Therapy (RPT) Device

[0053] A respiratory pressure therapy (RPT) device may be used individually or as part of a system to deliver one or more of a number of therapies described above, such as by operating the device to generate a flow of air for delivery to an interface to the airways. The flow of air may be pressure-controlled (for respiratory pressure therapies) or flow-controlled (for flow therapies such as HFT). Thus RPT devices may also act as flow therapy devices. Examples of RPT devices include a CPAP device and a ventilator.

[0054] Air pressure generators are known in a range of applications, e.g. industrial-scale ventilation systems. However, air pressure generators for medical applications have particular requirements not fulfilled by more generalised air pressure generators, such as the reliability, size and weight requirements of medical devices. In addition, even devices designed for medical treatment may suffer from shortcomings,pertaining to one or more of: comfort, noise, ease of use, efficacy, size, weight, manufacturability, cost, and reliability.

[0055] An example of the special requirements of certain RPT devices is acoustic noise.

[0056] Table of noise output levels of prior RPT devices (one specimen only, measured using test method specified in ISO 3744 in CPAP mode at 10 cmH20).

[0057] One known RPT device used for treating sleep disordered breathing is the S9 Sleep Therapy System, manufactured by ResMed Inc. Another example of an RPT device is a ventilator. Ventilators such as the ResMed Stellar™ Series of Adult and Paediatric Ventilators may provide support for invasive and non-invasive nondependent ventilation for a range of patients for treating a number of conditions such as but not limited to NMD, OHS and COPD.

[0058] The ResMed Elisee™ 150 ventilator and ResMed VS III™ ventilator may provide support for invasive and non-invasive dependent ventilation suitable for adult or paediatric patients for treating a number of conditions. These ventilators provide volumetric and barometric ventilation modes with a single or double limb circuit.RPT devices typically comprise a pressure generator, such as a motor-driven blower or a compressed gas reservoir, and are configured to supply a flow of air to the airway of a patient. In some cases, the flow of air may be supplied to the airway of the patient at positive pressure. The outlet of the RPT device is connected via an air circuit to a patient interface such as those described above.

[0059] The designer of a device may be presented with an infinite number of choices to make. Design criteria often conflict, meaning that certain design choices arefar from routine or inevitable. Furthermore, the comfort and efficacy of certain aspects may be highly sensitive to small, subtle changes in one or more parameters.2.2.3.3 Air circuit

[0060] 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.2.1.3.4 Humidifier

[0061] 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.

[0062] A range of artificial humidification devices and systems are known, however they may not fulfil the specialised requirements of a medical humidifier.

[0063] Medical humidifiers are used to increase humidity and / or temperature of the flow of air in relation to ambient air when required, typically where the patient may be asleep or resting (e.g. at a hospital). A medical humidifier for bedside placement may be small. A medical humidifier may be configured to only humidify and / or heat the flow of air delivered to the patient without humidifying and / or heating the patient’s surroundings. Room-based systems (e.g. a sauna, an air conditioner, or an evaporative cooler), for example, may also humidify air that is breathed in by the patient, however those systems would also humidify and / or heat the entire room, which may cause discomfort to the occupants. Furthermore, medical humidifiers may have more stringent safety constraints than industrial humidifiers

[0064] While a number of medical humidifiers are known, they can suffer from one or more shortcomings. Some medical humidifiers may provide inadequate humidification, some are difficult or inconvenient to use by patients.2.2.3.5 Data Management

[0065] There may be clinical reasons to obtain data to determine whether the patient prescribed with respiratory therapy has been “compliant”, e.g. that the patient has used their RPT device according to one or more “compliance rules”. One exampleof a compliance rule for CPAP therapy is that a patient, in order to be deemed compliant, is required to use the RPT device for at least four hours a night for at least 21 of 30 consecutive days. In order to determine a patient's compliance, a provider of the RPT device, such as a health care provider, may manually obtain data describing the patient's therapy using the RPT device, calculate the usage over a predetermined time period, and compare with the compliance rule. Once the health care provider has determined that the patient has used their RPT device according to the compliance rule, the health care provider may notify a third party that the patient is compliant.

[0066] There may be other aspects of a patient’s therapy that would benefit from communication of therapy data to a third party or external system.

[0067] Existing processes to communicate and manage such data can be one or more of costly, time-consuming, and error-prone.2.1.3.6 Vent technologies

[0068] 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.

[0069] The vent may comprise an orifice and gas may flow through the orifice in use of the mask. Many such vents are noisy. Others may become blocked in use and thus provide insufficient washout. Some vents may be disruptive of the sleep of a bed partner 1100 of the patient 1000, e.g. through noise or focussed airflow.

[0070] ResMed Inc. has developed a number of improved mask vent technologies, e.g. see International Patent Application Publication No. WO 1998 / 034665;International Patent Application Publication No. WO 2000 / 078381; US Patent No. 6,581,594; US Patent Application Publication No. US 2009 / 0050156; US Patent Application Publication No. 2009 / 0044808.

[0071] Table of noise of prior masks (ISO 17510-2:2007, 10 cmH20 pressure at Im)

[0072] (* one specimen only, measured using test method specified in ISO 3744 inCPAP mode at 10 cmH20)

[0073] Sound pressure values of a variety of objects are listed below2.2.4 Screening, Diagnosis, and Monitoring Systems

[0074] Polysomnography (PSG) is a conventional system for diagnosis and monitoring of cardio-pulmonary disorders, and typically involves expert clinical staff to apply the system. PSG typically involves the placement of 15 to 20 contact sensors on a patient in order to record various bodily signals such as electroencephalography (EEG), electrocardiography (ECG), electrooculograpy (EOG), electromyography (EMG), etc. PSG for sleep disordered breathing has involved two nights of observation of a patient in a clinic, one night of pure diagnosis and a second night of titration of treatment parameters by a clinician. PSG is therefore expensive and inconvenient. In particular, it is unsuitable for home screening / diagnosis / monitoring of sleep disordered breathing.

[0075] Screening and diagnosis generally describe the identification of a condition from its signs and symptoms. Screening typically gives a true / false result indicating whether or not a patient’s SDB is severe enough to warrant further investigation, while diagnosis may result in clinically actionable information. Screening and diagnosis tend to be one-off processes, whereas monitoring the progress of a condition can continue indefinitely. Some screening / diagnosis systems are suitable only for screening / diagnosis, whereas some may also be used for monitoring.

[0076] Clinical experts may be able to screen, diagnose, or monitor patients adequately based on visual observation of PSG signals. However, there are circumstances where a clinical expert may not be available, or a clinical expert may not be affordable. Different clinical experts may disagree on a patient’s condition. In addition, a given clinical expert may apply a different standard at different times.3 BRIEF SUMMARY OF THE TECHNOLOGY

[0077] 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.

[0078] A first aspect of the present technology relates to apparatus used in the screening, diagnosis, monitoring, amelioration, treatment or prevention of a respiratory disorder.

[0079] Another aspect of the present technology relates to methods used in the screening, diagnosis, monitoring, amelioration, treatment or prevention of a respiratory disorder.

[0080] 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.

[0081] One form of the present technology comprises a positioning and stabilising structure configured to provide a force to hold the seal-forming structure in a therapeutically effective position on the patient’s head. The positioning and stabilising structure includes at least one strap.

[0082] One form of the present technology comprises a patient interface comprising a plenum chamber, a seal-forming structure, and a positioning and stabilising structure.

[0083] One form of the present technology comprises patient interface comprising a plenum chamber pressurisable to a therapeutic pressure of at least 4 cmH20 above ambient air pressure. The plenum chamber includes at least one plenum chamber inlet port sized and structured to receive a flow of air at the therapeutic pressure for breathing by a patient. The patient interface also comprises a seal-forming structure that is constructed and arranged to form a seal with a region of the patient’s face surrounding an entrance to the patient’s airways. The seal -forming structure has a hole therein such that the flow of air at said therapeutic pressure is delivered to at least an entrance to the patient’s nares. The seal-forming structure is constructed and arranged to maintain said therapeutic pressure in the plenum chamber throughout the patient’s respiratory cycle in use. The patient interface also comprises a positioning and stabilising structure to provide a force to hold the seal-forming structure in a therapeutically effective position on the patient’s head.

[0084] Another aspect of one form of the present technology is a series of modular elements that may be interconnected in order to form different styles of patient interfaces.

[0085] In one form, there are at least two versions or styles of each modular element. The versions or styles may be interchangeably used with one another in order to form different modular assemblies.

[0086] One form of the present technology relates to a flow disruptor for a patient interface, the patient interface configured to deliver a flow of breathable gas to a patient for treatment of a respiratory disorder and comprising: a plenum chamber pressurisable to a therapeutic pressure of at least 6 cmH20 above ambient air pressure throughout a patient’s respiratory cycle in use, the plenum chamber comprising: a sealforming structure constructed and arranged to form a seal with a region of the patient’s face surrounding at least one entrance to the patient’s airways, and a shell configured to support the seal-forming structure in use, a connection port configured to receive the flow of breathable gas from a flow generator; and wherein the flow disruptor is configured to be positioned at or between the connection port and the at least one entrance to the patient’s airways, such that the flow disruptor at least partially obstructs the flow of breathable gas entering the patient’s airways.

[0087] In one form, the patient interface may comprise at least one clip, configured to attach the seal-forming structure to the shell.

[0088] In examples, the flow disruptor may be formed in or attached to the clip.

[0089] In examples, the flow disruptor may be releasably attached to the clip.

[0090] In one form, the flow disruptor may be formed in or attached to the shell.

[0091] In certain forms, the flow disruptor may comprise a front face which obstructs the flow of breathable gas wherein the front face obstructs less than or equal to 50% of the cross-sectional area between the connection port and the patient’s airways.

[0092] In certain forms, the flow disruptor may comprise a plurality of apertures. In some examples at least two of the plurality of apertures may be of different sizes to each other.

[0093] In examples, the plurality of apertures may comprise a first set of apertures 10002 A wherein each aperture of the first set of apertures has a first aperture size, anda second set of apertures wherein each aperture of the second set of apertures having a second size, where the second size is greater than the first size.

[0094] In further examples, the plurality of apertures may further comprise a third set of apertures, wherein each aperture of the third set of apertures has a third size, and wherein the third size is greater than the first size and second size.

[0095] In examples, the third set of apertures may be positioned distal to a central axis of the flow disruptor.

[0096] In some forms, the flow disruptor may have a wall thickness of between 1 mm and 3 mm inclusive.

[0097] In one form, the flow disrupter may be provided to the shell.

[0098] In some forms, the flow disruptor may comprise a bar extending between an inferior side of the shell and a superior side of the shell.

[0099] In examples, the bar may have a V-shaped cross-section.

[0100] In examples, the bar may be formed from two arms each having a first end and a second end, wherein the respective first ends are connected at a linking portion.

[0101] In examples, the linking portion may form a leading edge of the flow disruptor.

[0102] In examples, the respective second ends of the two arms may each form a trailing edge of the flow disruptor.

[0103] In examples, the flow disrupter may comprise a first bar and a second bar, wherein the first and second bars extend between an inferior side of the shell and a superior side of the shell and define a channel therebetween said first and second bars.

[0104] In examples, the first bar and the second bar may be arranged at an angle relative to the connection port.

[0105] In examples, the first bar and second bar may have a leading edge and a trailing edge.

[0106] In examples, the first bar and the second bar may be arranged with respect to each other such that the respective leading edges are closer together than the respective trailing edges.

[0107] In examples, the trailing edges of one or both of the first bar and the second bar may be contoured or serrated.

[0108] In one form, the flow disrupter may be provided to the connection port.

[0109] In examples, the flow disruptor may comprise at least a first arm and a second arm extending from an internal surface of the connection port into the path of the flow of breathable gas.

[0110] In examples, the first arm and second arm maybe provided to opposing internal surfaces of the connection port.

[0111] In examples, the flow disruptor may comprise three or more arms extending from an internal surface of the connection port into the path of the flow of breathable gas.

[0112] In examples, the arms may be arranged equidistance around the internal surface of the connection port.

[0113] In examples, at least one of the arms of the flow disruptor may be comprised of a first portion and a second portion.

[0114] In examples, the second portion may be at an angle relative to the first portion.

[0115] In examples, the arm may include a third portion, wherein the third portion is at an angle relative to the first portion and the second portion.

[0116] In examples, both the second portion of the arm and the third portion of the arm may extend from the first portion of the arm.

[0117] In examples, the second portion of the arm may be arranged to be anterior to the third portion of the arm.

[0118] In some forms, flow disruptor may be constructed of the same material as the seal-forming structure, the shell, or the connector. For example the material may be silicone or polycarbonate.

[0119] Another form of the present technology relates to a patient interface configured to deliver a flow of breathable gas to a patient for treatment of a respiratory disorder, the patient interface comprising: a plenum chamber pressurisable to a therapeutic pressure of at least 6 cmH20 above ambient air pressure throughout a patient’s respiratory cycle in use, the plenum chamber comprising: a seal -forming structure constructed and arranged to form a seal with a region of the patient’s face surrounding at least one entrance to the patient’s airways, and a shell configured to support the seal-forming structure in use, a connection port configured to receive the flow of breathable gas from a flow generator; and a flow disruptor positioned at or between the connection port and the at least one entrance to the patient’s airways, suchthat the flow disruptor at least partially obstructs the flow of breathable gas entering the patient’s airways.

[0120] Another aspect of one form of the present technology is a patient interface that is moulded or otherwise constructed with a perimeter shape which is complementary to that of an intended wearer.

[0121] An aspect of one form of the present technology is a method of manufacturing apparatus.

[0122] Another aspect of one form of the present technology is a method of assembling a modular system comprising selecting a positioning and stabilising structure, and connecting the positioning and stabilising structure to either a first cushion or a second cushion.

[0123] 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.

[0124] An aspect of one form of the present technology is a portable RPT device that may be carried by a person, e.g., around the home of the person.

[0125] An aspect of one form of the present technology is a patient interface that may be washed in a home of a patient, e.g., in soapy water, without requiring specialised cleaning equipment. An aspect of one form of the present technology is a humidifier tank that may be washed in a home of a patient, e.g., in soapy water, without requiring specialised cleaning equipment.

[0126] The methods, systems, devices and apparatus described may be implemented so as to improve the functionality of a processor, such as a processor of a specific purpose computer, respiratory monitor and / or a respiratory therapy apparatus. Moreover, the described methods, systems, devices and apparatus can provide improvements in the technological field of automated management, monitoring and / or treatment of respiratory conditions, including, for example, sleep disordered breathing.

[0127] 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.

[0128] Other features of the technology will be apparent from consideration of the information contained in the following detailed description, abstract, drawings and claims.4 BRIEF DESCRIPTION OF THE DRAWINGS

[0129] 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:4.1 RESPIRATORY THERAPY SYSTEMS

[0130] Fig. 1 A shows a system including a patient 1000 wearing a patient interface 3000, in the form of nasal pillows, receiving a supply of air at positive pressure from an RPT device 4000. Air from the RPT device 4000 is humidified in a humidifier 5000, and passes along an air circuit 4170 to the patient 1000. A bed partner 1100 is also shown. The patient is sleeping in a supine sleeping position.

[0131] Fig. IB shows a system including a patient 1000 wearing a patient interface 3000, in the form of a nasal mask, receiving a supply of air at positive pressure from an RPT device 4000. Air from the RPT device is humidified in a humidifier 5000, and passes along an air circuit 4170 to the patient 1000.

[0132] Fig. 1C shows a system including a patient 1000 wearing a patient interface 3000, in the form of a full-face mask, receiving a supply of air at positive pressure from an RPT device 4000. Air from the RPT device is humidified in a humidifier 5000, and passes along an air circuit 4170 to the patient 1000. The patient is sleeping in a side sleeping position.4.2 RESPIRATORY SYSTEM AND FACIAL ANATOMY

[0133] 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.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] 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.

[0138] 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.

[0139] Fig. 2G shows a side view of the superficial features of a nose.

[0140] Fig. 2H shows subcutaneal structures of the nose, including lateral cartilage, septum cartilage, greater alar cartilage, lesser alar cartilage, sesamoid cartilage, nasal bone, epidermis, adipose tissue, frontal process of the maxilla and fibrofatty tissue.

[0141] 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.

[0142] Fig. 2 J 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.

[0143] 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.

[0144] Fig. 2L shows an anterolateral view of a nose.4.3 PATIENT INTERFACE

[0145] Fig. 3A shows a patient interface in the form of a nasal mask in accordance with one form of the present technology.

[0146] Fig. 3A-1 shows forces acting on the patient interface of Fig. 3A, while in use.

[0147] Fig. 3B shows a schematic of a cross-section through a structure at a point. An outward normal at the point is indicated. The curvature at the point has a positive sign, and a relatively large magnitude when compared to the magnitude of the curvature shown in Fig. 3C.

[0148] Fig. 3C shows a schematic of a cross-section through a structure at a point. An outward normal at the point is indicated. The curvature at the point has a positive sign, and a relatively small magnitude when compared to the magnitude of the curvature shown in Fig. 3B.

[0149] Fig. 3D shows a schematic of a cross-section through a structure at a point. An outward normal at the point is indicated. The curvature at the point has a value of zero.

[0150] Fig. 3E shows a schematic of a cross-section through a structure at a point. An outward normal at the point is indicated. The curvature at the point has a negative sign, and a relatively small magnitude when compared to the magnitude of the curvature shown in Fig. 3F.

[0151] Fig. 3F shows a schematic of a cross-section through a structure at a point. An outward normal at the point is indicated. The curvature at the point has a negative sign, and a relatively large magnitude when compared to the magnitude of the curvature shown in Fig. 3E.

[0152] Fig. 3G shows a cushion for a mask that includes two pillows. An exterior surface of the cushion is indicated. An edge of the surface is indicated. Dome and saddle regions are indicated.

[0153] Fig. 3H shows a cushion for a mask. An exterior surface of the cushion is indicated. An edge of the surface is indicated. A path on the surface between points A and B is indicated. A straight line distance between A and B is indicated. Two saddle regions and a dome region are indicated.

[0154] Fig. 31 shows the surface of a structure, with a one dimensional hole in the surface. The illustrated plane curve forms the boundary of a one dimensional hole.

[0155] Fig. 3J shows a cross-section through the structure of Fig.31. The illustrated surface bounds a two dimensional hole in the structure of Fig. 31.

[0156] Fig. 3K shows a perspective view of the structure of Fig. 31, including the two dimensional hole and the one dimensional hole. Also shown is the surface that bounds a two dimensional hole in the structure of Fig. 31.

[0157] Fig. 3L shows a mask having an inflatable bladder as a cushion.

[0158] Fig. 3M shows a cross-section through the mask of Fig. 3L, and shows the interior surface of the bladder. The interior surface bounds the two dimensional hole in the mask.

[0159] Fig. 3N shows a further cross-section through the mask of Fig. 3L. The interior surface is also indicated.

[0160] Fig. 30 illustrates a left-hand rule.

[0161] Fig. 3P illustrates a right-hand rule.

[0162] Fig. 3Q shows a left ear, including the left ear helix.

[0163] Fig. 3R shows a right ear, including the right ear helix.

[0164] Fig. 3S shows a right-hand helix.

[0165] Fig. 3T shows a view of a mask, including the sign of the torsion of the space curve defined by the edge of the sealing membrane in different regions of the mask.

[0166] Fig. 3U shows a view of a plenum chamber 3200 showing a sagittal plane and a mid-contact plane.

[0167] Fig. 3 V shows a view of a posterior of the plenum chamber of Fig. 3U. The direction of the view is normal to the mid-contact plane. The sagittal plane in Fig. 3 V bisects the plenum chamber into left-hand and right-hand sides.

[0168] Fig. 3W shows a cross-section through the plenum chamber of Fig. 3 V, the cross-section being taken at the sagittal plane shown in Fig. 3 V. A ‘mid-contact’ plane is shown. The mid-contact plane is perpendicular to the sagittal plane. The orientation of the mid-contact plane corresponds to the orientation of a chord 3210 which lies on the sagittal plane and just touches the cushion of the plenum chamber at two points on the sagittal plane: a superior point 3220 and an inferior point 3230. Depending on the geometry of the cushion in this region, the mid-contact plane may be a tangent at both the superior and inferior points.

[0169] Fig. 3X shows the plenum chamber 3200 of Fig. 3U in position for use on a face. The sagittal plane of the plenum chamber 3200 generally coincides with the midsagittal plane of the face when the plenum chamber is in position for use. The mid-contact plane corresponds generally to the ‘plane of the face’ when the plenum chamber is in position for use. In Fig. 3X the plenum chamber 3200 is that of a nasal mask, and the superior point 3220 sits approximately on the sellion, while the inferior point 3230 sits on the lip superior.

[0170] Fig. 3Y shows a patient interface in the form of a nasal cannula in accordance with one form of the present technology.

[0171] Fig. 3Z shows a patient interface having conduit headgear, in accordance with one form of the present technology.

[0172] Fig. 3Z-1 shows forces acting on the patient interface of Fig. 3Z, while in use.4.4 RPT DEVICE

[0173] Fig. 4 A shows an RPT device in accordance with one form of the present technology.

[0174] Fig. 4B is a schematic diagram of the pneumatic path of an RPT device in accordance with one form of the present technology. The directions of upstream and downstream are indicated with reference to the blower and the patient interface. The blower is defined to be upstream of the patient interface and the patient interface is defined to be downstream of the blower, regardless of the actual flow direction at any particular moment. Items which are located within the pneumatic path between the blower and the patient interface are downstream of the blower and upstream of the patient interface.4.5 HUMIDIFIER

[0175] Fig. 5 A shows an isometric view of a humidifier in accordance with one form of the present technology.

[0176] Fig. 5B shows an isometric view of a humidifier in accordance with one form of the present technology, showing a humidifier reservoir 5110 removed from the humidifier reservoir dock 5130.4.6 BREATHING WAVEFORMS

[0177] Fig. 6 shows a model typical breath waveform of a person while sleeping.4.7 MODULARITY

[0178] Fig. 7 A shows a perspective view of a cushion of a patient interface configured to be worn by a patient and convey pressurized air to the patient’s nose and the patient’s mouth.

[0179] Fig. 7B shows a perspective view of a cushion of a patient interface configured to be worn by a patient and convey pressurized air to the patient’s nose.

[0180] Fig. 7C shows a perspective view of tubes usable with either the cushion of Fig. 7 A or the cushion of Fig. 7B.

[0181] Fig. 7D shows a perspective view of rigi diser arms usable with either the cushion of Fig. 7 A of the cushion of Fig. 7B.

[0182] Fig. 7E shows a perspective view of headgear straps usable with the cushion of Fig. 7 A.

[0183] Fig. 7F shows a perspective view of headgear straps usable with the cushion of Fig. 7B.

[0184] Fig. 7G shows a front view of a pair of sleeves that is removably fitted to either the tubes of Fig. 7C or the rigi diser arms of Fig. 7D.

[0185] Fig. 7H shows a front view of a full sleeve that is removably fitted to the rigi diser arms of Fig. 7D.

[0186] Fig. 71 shows a front perspective view of yet another alternate form of a full sleeve that is removably fitted to the rigi diser arms of Fig. 7D.

[0187] Fig. 7J is a front view of a patient wearing the cushion of Fig. 7A connected to the tubes of Fig. 7C, the headgear straps of Fig. 7E, and the sleeves of Fig. 7G.

[0188] Fig. 7K is a front view of a patient wearing the cushion of Fig. 7A connected to the rigi diser arms of Fig. 7D, the headgear straps of Fig. 7E, and the sleeve of Fig. 7H.

[0189] Fig. 7L is a front view of a patient wearing the cushion of Fig. 7B connected to the conduit headgear of Fig. 7C, and the headgear straps of Fig. 7F.

[0190] Fig. 7M is a front view of a patient wearing the cushion of Fig. 7B connected to the rigi disier arms of Fig. 7D, the headgear straps of Fig. 7F, and the sleeve of Fig. 71.

[0191] Fig. 7N is an isolated perspective view of the vent of Fig. 7L.

[0192] Fig. 70 is an isolated perspective view of a portion of the air circuit of Fig.7M.

[0193] Fig. 7P is a schematic view illustrating the possible combinations of the patient interfaces.4.8 FLOW DIFFUSERS

[0194] Fig. 8 shows a cross-sectional front view of a patient interface in accordance with one form of the technology.

[0195] Fig. 9A shows a top front perspective view of a shell of a patient interface in accordance with another form of the technology.

[0196] Fig. 9B shows a rear perspective view of the shell of Fig. 9 A.

[0197] Fig. 9C shows a front view of a clip for use with the shell of Fig. 9 A.

[0198] Fig. 9D shows a rear view of the clip of Fig. 9C.

[0199] Fig. 10A shows a top perspective view of a patient interface in accordance with another form of the technology.

[0200] Fig. 10B shows a rear view of the patient interface of Fig. 10A.

[0201] Fig. 10C shows a perspective rear view of the flow disruptor and shell of the patient interface of Fig. 10 A.

[0202] Fig. 10D shows a partial cross sectional side view of the flow disruptor and shell of Fig. 10C.

[0203] Fig. 10E shows a partial cross sectional perspective side view of the patient interface of Fig. 10A.

[0204] Fig. 10F shows a flow disruptor in accordance with another form of the technology.

[0205] Fig. 10G shows a flow disruptor in accordance with another form of the technology.

[0206] Fig. 10H shows a flow disruptor in accordance with another form of the technology.

[0207] Fig. 11 A shows a rear view of a patient interface in accordance with another form of the technology.

[0208] Fig. 1 IB shows a perspective rear view of the shell of the patient interface of Fig. 11 A.

[0209] Fig. 12A shows a perspective front view of the shell of a patient interface in accordance with another form of the technology.

[0210] Fig. 12B shows a cross-sectional top view along line a-a of the shell of Fig.12 A.

[0211] Fig. 12C shows a graphical representation of a velocity contour plot of air flow through a patient interface provided with the shell of Figs. 12A and 12B.

[0212] Fig. 13 A shows a perspective front view of the shell of a patient interface in accordance with another form of the technology.

[0213] Fig. 13B shows a cross-sectional side view along line a-a of the shell of Fig. 13A.

[0214] Fig. 13C shows a graphical representation of a velocity contour plot of air flow through a patient interface provided with the shell of Figs. 13 A and 13B.

[0215] Fig. 14A shows a front view of the shell of a patient interface in accordance with another form of the technology.

[0216] Fig. 14B shows a front view of the shell of a patient interface in accordance with another form of the technology.

[0217] Fig. 14C shows a front view of the shell of a patient interface in accordance with yet another form of the technology.

[0218] Fig. 14D shows a front view of the shell of a patient interface in accordance with another form of the technology.

[0219] Fig. 14E shows a cross-sectional side view along line a-a of the shell of Fig. 14D.

[0220] Fig. 14F shows a front view of the shell of a patient interface in accordance with yet another form of the technology

[0221] Fig. 15A shows a front view of the shell of a patient interface in accordance with another form of the technology

[0222] Fig. 15B shows a close up perspective view of a portion of the flow disruptor of Fig. 15A.5 DETAILED DESCRIPTION OF EXAMPLES OF THETECHNOLOGY

[0223] Before the present technology is described in further detail, it is to be understood that the technology is not limited to the particular examples described herein, which may vary. It is also to be understood that the terminology used in this disclosure is for the purpose of describing only the particular examples discussed herein, and is not intended to be limiting.

[0224] 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 oneor more features of another example or other examples. In addition, any single feature or combination of features in any of the examples may constitute a further example.5.1 THERAPY

[0225] 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.

[0226] 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.

[0227] In certain examples of the present technology, mouth breathing is limited, restricted or prevented.5.2 RESPIRATORY THERAPY SYSTEMS

[0228] In one form, the present technology comprises a respiratory therapy system for treating a respiratory disorder. The respiratory therapy system may comprise an RPT device 4000 for supplying a flow of air to the patient 1000 via an air circuit 4170 and a patient interface 3000 or 3800.5.3 PATIENT INTERFACE

[0229] A non-invasive patient interface 3000, such as that shown in Fig. 3A, in accordance with one aspect of the present technology comprises the following functional aspects: a seal-forming structure 3100, a plenum chamber 3200, a positioning and stabilising structure 3300, a vent 3400, one form of connection port 3600 for connection to air circuit 4170, and a forehead support 3700. In some forms a functional aspect may be provided by one or more physical components. In some forms, one physical component may provide one or 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.

[0230] As shown in Fig. 3Z, a non-invasive patient interface 3000 in accordance with another aspect of the present technology comprises the following functional aspects: a seal-forming structure 3100, a plenum chamber 3200, a positioning and stabilising structure 3300, a vent 3400 and one form of connection port 3600 for connection to an air circuit (such as the air circuit 4170 shown in Figs. 1 A-1C). The plenum chamber 3200 may be formed of one or more modular components (e.g., acushion module 3150 together with the seal -forming structure 3100) in the sense that it or they can be replaced with different components, for example components of a different size.

[0231] An unsealed patient interface 3800, in the form of a nasal cannula, includes nasal prongs 3810a, 3810b which can deliver air to respective nares of the patient 1000 via respective orifices in their tips. Such nasal prongs do not generally form a seal with the inner or outer skin surface of the nares. This type of interface results in one or more gaps that are present in use by design (intentional) but they are typically not fixed in size such that they may vary unpredictably by movement during use. This can present a complex pneumatic variable for a respiratory therapy system when pneumatic control and / or assessment is implemented, unlike other types of mask-based respiratory therapy systems. The air to the nasal prongs may be delivered by one or more air supply lumens 3820a, 3820b that are coupled with the nasal cannula-type unsealed patient interface 3800. The lumens 3820a, 3820b lead from the nasal cannula-type unsealed patient interface 3800 to a respiratory therapy device via an air circuit. The unsealed patient interface 3800 is particularly suitable for delivery of flow therapies, in which the RPT device generates the flow of air at controlled flow rates rather than controlled pressures. The “vent” or gap at the unsealed patient interface 3800, through which excess airflow escapes to ambient, is the passage between the end of the prongs 3810a and 3810b of the nasal cannula-type unsealed patient interface 3800 via the patient’s nares to atmosphere.

[0232] 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.

[0233] 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 cmH20 with respect to ambient.5.3.1 Seal-forming structure

[0234] In one form of the present technology, a seal-forming structure 3100 provides a target seal-forming region, and may additionally provide a cushioning function. The target seal-forming region is a region on the seal -forming structure 3100 where sealing may occur. The region where sealing actually occurs- the actual sealingsurface- may change within a given treatment session, from day to day, and from patient to patient, depending on a range of factors including for example, where the patient interface was placed on the face, tension in the positioning and stabilising structure and the shape of a patient’s face.

[0235] In one form the target seal-forming region is located on an outside surface of the seal-forming structure 3100.

[0236] In certain forms of the present technology, the seal-forming structure 3100 is constructed from a biocompatible material, e.g. silicone rubber.

[0237] A seal -forming structure 3100 in accordance with the present technology may be constructed from a soft, flexible, resilient material such as silicone.

[0238] 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.5.3.1.1 Sealing mechanisms

[0239] In one form, the seal -forming structure includes a sealing flange utilizing a pressure assisted sealing mechanism. In use, the sealing flange can readily respond to a system positive pressure in the interior of the plenum chamber 3200 acting on its underside to urge it into tight sealing engagement with the face. The pressure assisted mechanism may act in conjunction with elastic tension in the positioning and stabilising structure.

[0240] In one form, the seal -forming structure 3100 comprises a sealing flange and a support flange. The sealing flange comprises a relatively thin member with a thickness of less than about 1mm, for example about 0.25mm to about 0.45mm, which extends around the perimeter of the plenum chamber 3200. Support flange may be relatively thicker than the sealing flange. The support flange is disposed between the sealing flange and the marginal edge of the plenum chamber 3200, and extends at least part of the way around the perimeter. The support flange is or includes a spring-like element and functions to support the sealing flange from buckling in use.

[0241] In one form, the seal-forming structure may comprise a compression sealing portion or a gasket sealing portion. In use the compression sealing portion, orthe gasket sealing portion is constructed and arranged to be in compression, e.g. as a result of elastic tension in the positioning and stabilising structure.

[0242] In one form, the seal-forming structure comprises a tension portion. In use, the tension portion is held in tension, e.g. by adjacent regions of the sealing flange.

[0243] In one form, the seal-forming structure comprises a region having a tacky or adhesive surface.

[0244] In certain forms of the present technology, a seal-forming structure may comprise one or more of a pressure-assisted sealing flange, a compression sealing portion, a gasket sealing portion, a tension portion, and a portion having a tacky or adhesive surface.5.3.1.2 Nose bridge or nose ridge region

[0245] In one form, the non-invasive patient interface 3000 comprises a sealforming structure that forms a seal in use on a nose bridge region or on a nose-ridge region of the patient's face.

[0246] In one form, the seal-forming structure includes a saddle-shaped region constructed to form a seal in use on a nose bridge region or on a nose-ridge region of the patient's face.5.3.1.3 Upper lip region

[0247] In one form, the non-invasive patient interface 3000 comprises a sealforming structure that forms a seal in use on an upper lip region (that is, the lip superior) of the patient's face.

[0248] In one form, the seal-forming structure includes a saddle-shaped region constructed to form a seal in use on an upper lip region of the patient's face.5.3.1.4 Chin-region

[0249] In one form the non-invasive patient interface 3000 comprises a sealforming structure that forms a seal in use on a chin-region of the patient's face.

[0250] In one form, the seal-forming structure includes a saddle-shaped region constructed to form a seal in use on a chin-region of the patient's face.5.3.1.5 Forehead region

[0251] In one form, the seal -forming structure that forms a seal in use on a forehead region of the patient's face. In such a form, the plenum chamber may cover the eyes in use.5.3.1.6 Nasal pillows

[0252] In one form the seal-forming structure of the non-invasive patient interface 3000 comprises a pair of nasal puffs, or nasal pillows, each nasal puff or nasal pillow being constructed and arranged to form a seal with a respective naris of the nose of a patient.

[0253] Nasal pillows in accordance with an aspect of the present technology include: a frusto-cone, at least a portion of which forms a seal on an underside of the patient's nose, a stalk, a flexible region on the underside of the frusto-cone and connecting the frusto-cone to the stalk. In addition, the structure to which the nasal pillow of the present technology is connected includes a flexible region adjacent the base of the stalk. The flexible regions can act in concert to facilitate a universal joint structure that is accommodating of relative movement both displacement and angular of the frusto-cone and the structure to which the nasal pillow is connected. For example, the frusto-cone may be axially displaced towards the structure to which the stalk is connected.5.3.1.7 Nose-only Masks

[0254] In one form, the patient interface 3000 comprises a seal-forming structure 3100 configured to seal around an entrance to the patient’s nasal airways but not around the patient’s mouth. The seal -forming structure 3100 may be configured to seal to the patient’s lip superior. The patient interface 3000 may leave the patient’s mouth uncovered. This patient interface 3000 may deliver a supply of air or breathable gas to both nares of patient 1000 and not to the mouth. This type of patient interface may be identified as a nose-only mask.

[0255] One form of nose-only mask according to the present technology is what has traditionally been identified as a “nasal mask”, having a seal-forming structure 3100 configured to seal on the patient’s face around the nose and over the bridge of the nose. A nasal mask may be generally triangular in shape. In one form, the non-invasive patient interface 3000 comprises a seal-forming structure 3100 that forms a seal in use to an upper lip region (e.g. the lip superior), to the patient’s nose bridge or at least a portion of the nose ridge above the pronasale, and to the patient's face on each lateral side of the patient’s nose, for example proximate the patient’s nasolabial sulci. The patient interface 3000 shown in Fig. IB has this type of seal-forming structure 3100.This patient interface 3000 may deliver a supply of air or breathable gas to both nares of patient 1000 through a single orifice.

[0256] Another form of nose-only mask may seal around an inferior periphery of the patient’s nose without engaging the user’s nasal ridge. This type of patient interface 3000 may be identified as a “nasal cradle” mask and the seal-forming structure 3100 may be identified as a “nasal cradle cushion”, for example. In one form, for example as shown in Fig. 3Z, 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 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.

[0257] In some forms, a nose-only mask may comprise nasal pillows, described above.5.3.1.8 Nose and Mouth Masks

[0258] In one form, the patient interface 3000 comprises a seal-forming structure 3100 configured to seal around an entrance to the patient’s nasal airways and also around the patient’s mouth. The seal -forming structure 3100 may be configured to seal to the patient’s face proximate a chin region. This patient interface 3000 may deliver a supply of air or breathable gas to both nares and to the mouth of patient 1000. This type of patient interface may be identified as a nose and mouth mask.

[0259] One form of nose-and-mouth mask according to the present technology is what has traditionally been identified as a “full-face mask”, having a seal-forming structure 3100 configured to seal on the patient’s face around the nose, below the mouth and over the bridge of the nose. A nose-and-mouth mask may be generallytriangular in shape. In one form the patient interface 3000 comprises a seal-forming structure 3100 that forms a seal in use to a patient’s chin-region (which may include the patient’s lip inferior and / or a region directly inferior to the lip inferior), to the patient’s nose bridge or at least a portion of the nose ridge superior to the pronasale, and to cheek regions of the patient's face. The patient interface 3000 shown in Fig. 1C is of this type. This patient interface 3000 may deliver a supply of air or breathable gas to both nares and mouth of patient 1000 through a single orifice. This type of sealforming structure 3100 may be referred to as a “nose-and-mouth cushion”.

[0260] In another form the patient interface 3000 comprises a seal-forming structure 3100 that forms a seal in use on a patient’s chin region (which may include the patient’s lip inferior and / or a region directly inferior to the lip inferior), to an inferior and / or an anterior surface of a pronasale portion of the patient’s nose, to the alae of the patient’s nose and to the patient’s face on each lateral side of the patient’s nose, for example proximate the nasolabial sulci. The seal-forming structure 3100 may also form a seal against a patient’s lip superior. A patient interface 3000 having this type of seal-forming structure may have a single opening configured to deliver a flow of air or breathable gas to both nares and mouth of a patient, may have an oral hole configured to provide air or breathable gas to the mouth and a nasal hole configured to provide air or breathable gas to the nares, or may have an oral hole for delivering air to the patient’s mouth and two nasal holes for delivering air to respective nares. This type of patient interface 3000 may have a nasal portion and an oral portion, the nasal portion sealing to the patient’s face at similar locations to a nasal cradle mask.

[0261] In a further form of nose and mouth mask, the patient interface 3000 may comprise a seal -forming structure 3100 having a nasal portion comprising nasal pillows and an oral portion configured to form a seal to the patient’s face around the patient’s mouth.

[0262] In some forms, the seal -forming structure 3100 may have a nasal portion that is separate and distinct from an oral portion. In other forms, a seal-forming structure 3100 may form a contiguous seal around the patient’s nose and mouth.

[0263] It is to be understood that the above examples of different forms of patient interface 3000 do not constitute an exhaustive list of possible configurations. In some forms a patient interface 3000 may comprise a combination of different features of the above described examples of nose-only and nose and mouth masks.5.3.2 Plenum chamber

[0264] 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. 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 is 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. In some forms, the plenum chamber 3200 and the seal-forming structure 3100 are formed from a single homogeneous piece of material.

[0265] In certain forms of the present technology, the plenum chamber 3200 does not cover the eyes of the patient in use. In other words, the eyes are outside the pressurised volume defined by the plenum chamber. Such forms tend to be less obtrusive and / or more comfortable for the wearer, which can improve compliance with therapy.

[0266] In certain forms of the present technology, the plenum chamber 3200 is constructed from a transparent material, e.g. a transparent polycarbonate. The use of a transparent material can reduce the obtrusiveness of the patient interface, and help improve compliance with therapy. The use of a transparent material can aid a clinician to observe how the patient interface is located and functioning.

[0267] 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.

[0268] 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.

[0269] 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 of0.7MPa or less, for example between 0.7MPa and 0.3MPa. An example of such a material is silicone.5.3.2.1 Multiple Openings

[0270] As shown in Figs. 7A and 7B, different plenum chambers 3200-1, 3200-2 may be formed as part of a multi -opening cushion 3050-1, 3050-2. In the illustrated examples, the cushions 3050-1, 3050-2 each include three openings, although an alternate cushion may be formed with greater or fewer openings.

[0271] In some forms, the different openings may serve different functions. For example, some openings may be exclusively inlet openings, while other openings may be exclusively outlet openings.

[0272] In other forms, at least one opening may serve two different functions. For example, one opening may operate as both an inlet and an outlet during the same breathing cycle.

[0273] The plurality of openings may allow for a variety of configurations of air delivery to the plenum chamber 3200-1, 3200-2. For example, depending on patient need and / or patient comfort, the patient may use a given cushion 3050-1, 3050-2 in a “tube-up” configuration (e.g., using conduit headgear - described below) or a “tubedown” configuration (e.g., using a single conduit in front of the patient’s face).5.3.2.1.1 Nose and Mouth Mask

[0274] As shown in Fig. 7A, the plenum chamber 3200-1 includes a pair of plenum chamber inlet ports 3254-1, which may be used to convey gas into and / or out of the plenum chamber 3200-1. The plenum chamber inlet ports 3254-1 may be disposed on opposite sides (e.g., left and right sides) of the plenum chamber 3200-1.

[0275] In some forms, the plenum chamber 3200-1 may also include at least one vent opening 3402-1 (see e.g., Fig. 7A). The vent opening 3402-1 may be disposed in a center of the plenum chamber 3200-1. For example, the vent opening 3402-1 may be disposed between the plenum chamber inlet ports 3254-1.

[0276] In some forms, the plenum chamber 3200-1 may include a pair of grooves 3266-1. Each groove 3266-1 may be disposed proximate to one of the plenum chamber inlet ports 3254-1. Each groove 3266-1 may form a partially recessed surface.5.3.2.1.2 Nose-only Mask

[0277] The plenum chamber 3200-2 of a nasal only cushion 3050-2 may be similar to the plenum chamber 3200-1 of the mouth and nose cushion 3050-1. Onlysome similarities and differences between the plenum chambers 3200-1, 3200-2 may be described below.

[0278] As shown in Fig. 7B, the plenum chamber 3200-2 includes a pair of plenum chamber inlet ports 3254-2, which may be used to convey gas into and / or out of the plenum chamber 3200-2. The plenum chamber inlet ports 3254-2 may be disposed on opposite sides (e.g., left and right sides) of the plenum chamber 3200-2.

[0279] In some forms, the plenum chamber 3200-2 may also include at least one vent opening 3402-2 (see e.g., Fig. 7B). The vent opening 3402-2 may be disposed in a center of the plenum chamber 3200-2. For example, the vent opening 3402-2 may be disposed between the plenum chamber inlet ports 3254-2.

[0280] In some forms, the plenum chamber 3200-2 may include a pair of grooves 3266-2. Each groove 3266-2 may be disposed proximate to one of the plenum chamber inlet ports 3254-2. Each groove 3266-2 may form a partially recessed surface.5.3.3 Positioning and stabilising structure

[0281] The seal-forming structure 3100 of the patient interface 3000 of the present technology may be held in sealing position in use by the positioning and stabilising structure 3300. The positioning and stabilising structure 3300 may comprise and function as “headgear” since it engages the patient’s head in order to hold the patient interface 3000 in a sealing position. Examples of a positioning and stabilising structure may be shown in Figs. 3 A and 3A-1.

[0282] 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 (i.e., Fplenum).

[0283] 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.

[0284] With continued reference to Fig. 3A-1, the positioning and stabilising structure 3300 provides a force FPSS that assists in maintaining the plenum chamber 3200 in the sealing position on the patient’s face. The positioning and stabilising force FPSS may be the resultant force from the various forces of the different elements of the positioning and stabilising structure 3300. For example, headgear straps may individually provide a strap force Fstrap in order to hold the seal-forming structure 3100 against the patient’ s face. The force Fstrap may also be directed at least partiallyin the superior direction in order to overcome the gravitational force Fg. The gravitational force Fg may be specifically shown for the seal-forming structure 3100 and the plenum chamber 3200, but gravity would act on the entirely of the patient interface 3000 (i.e., in the same direction as the illustrated gravitational force Fg).

[0285] The gravitational force Fg may be opposed by a frictional force Ff, which may act in a direction directly opposite of the gravitational force Fg. As gravity pulls the seal -forming structure 3100 and the plenum chamber 3200 in the inferior direction (as viewed in Fig. 3A-1), the frictional force Ff would act in the superior direction (e.g., against a patient’s face). For example, the patient may experience the frictional force Ff against his lip superior (and / or other surfaces of the patient’s face in contact with the seal-forming structure 3100) in order to oppose the motion in the inferior direction (which may help to stabilising the cushion in place). Although the frictional force Ff is shown specifically opposing the gravitational force Fg of the seal -forming structure 3100 and the plenum chamber 3200, components of an overall frictional force (not shown) would also oppose the gravitational force Fg associated with the positioning and stabilising structure 3300 and any other portions of the patient interface 3000. A force of friction can act along any place where the patient interface 3000 contacts the patient’s skin (or hair). The frictional force Ff extends in the opposite direction of the gravitational force Fg and along the patient’s skin (or hair). In some forms the gravitiational force Fg may also be countered by vertical components of the reaction force from the patient’s face acting on the seal -forming structure 3100, for example at the nose ridge and chin regions of the patient’s face, for example.

[0286] In some forms, the sum of the various forces may equal zero so that the patient interface 3000 is at equilibrium (e.g., not moving along the patient’s face while in use). Specifically, the gravitational force Fg and the blowout force Fplenum tend to move the seal-forming structure 3100 away from the desired sealing position. The positioning and stabilising force FPSS is applied in order to counteract the gravitational force Fg and the blowout force Fplenum (as well as any frictional forces Ff) and keep the seal-forming structure 3100 properly situated. Although the positioning and stabilising force FPSS may exceed the sum of the gravitational force Fg and the blowout force Fplenum (with any additional positioning and stabilising force FPSS being balanced by reaction force from the patient’s head acting on the portions of patient interface 3000) and still maintain the seal-forming structure 3100 inan appropriate sealing position, patient comfort may be sacrificed. Maximum patient comfort may be achieved when the net force on the patient interface 3000 is zero and the positioning and stabilising force FPSS is exactly strong enough to achieve this. In some examples the positioning and stabilising structure 3300 may be adjustable such that when fitted the positioning and stabilising force FPSS is greater than required to exactly balance the gravitational force Fg and the blowout force Fplenum to hold the patient interface 3000 against the patient’s head tightly enough that disruptive forces which may be experienced in use (such as tube drag or lateral shunting of the plenum chamber 3200 during side sleeping) do not disrupt the seal. As described below, various positions of the patient’s head while using the patient interface 3000 may determine the positioning and stabilising force FPSS necessary to achieve equilibrium.

[0287] 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.

[0288] In one form of the present technology, a positioning and stabilising structure 3300 is provided that is configured in a manner consistent with being worn by a patient while sleeping. In one example the positioning and stabilising structure 3300 has a low profile, or cross-sectional thickness, to reduce the perceived or actual bulk of the apparatus. In one example, the positioning and stabilising structure 3300 comprises at least one strap having a rectangular cross-section. In one example the positioning and stabilising structure 3300 comprises at least one flat strap.

[0289] 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.

[0290] 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.

[0291] In one form of the present technology, a positioning and stabilising structure 3300 is provided with a decoupling portion located between an anterior portion of the positioning and stabilising structure 3300, and a posterior portion of thepositioning and stabilising structure 3300. The decoupling portion does not resist compression and may be, e.g. a flexible or floppy strap. The decoupling portion is constructed and arranged so that when the patient lies with their head on a pillow, the presence of the decoupling portion prevents a force on the posterior portion from being transmitted along the positioning and stabilising structure 3300 and disrupting the seal.

[0292] In one form of the present technology, a positioning and stabilising structure 3300 comprises a strap constructed from a laminate of a fabric patientcontacting layer, a foam inner layer and a fabric outer layer. In one form, the foam is porous to allow moisture, (e.g., sweat), to pass through the strap. In one form, the fabric outer layer comprises loop material to engage with a hook material portion.

[0293] In certain forms of the present technology, a positioning and stabilising structure 3300 comprises a strap that is extensible, e.g. resiliently extensible. For example the strap may be configured in use to be in tension, and to direct a force to draw a seal-forming structure into sealing contact with a portion of a patient’s face. In an example the strap may be configured as a tie.

[0294] In one form of the present technology, the positioning and stabilising structure comprises a first tie, the first tie being constructed and arranged so that in use at least a portion of an inferior edge thereof passes superior to an otobasion superior of the patient’s head and overlays a portion of a parietal bone without overlaying the occipital bone.

[0295] In one form of the present technology suitable for a nasal-only mask or for a full-face mask, the positioning and stabilising structure includes a second tie, the second tie being constructed and arranged so that in use at least a portion of a superior edge thereof passes inferior to an otobasion inferior of the patient’s head and overlays or lies inferior to the occipital bone of the patient’s head.

[0296] In one form of the present technology suitable for a nasal-only mask or for a full-face mask, the positioning and stabilising structure includes a third tie that is constructed and arranged to interconnect the first tie and the second tie to reduce a tendency of the first tie and the second tie to move apart from one another.

[0297] In certain forms of the present technology, a positioning and stabilising structure 3300 comprises a strap that is bendable and e.g. non-rigid. An advantage of this aspect is that the strap is more comfortable for a patient to lie upon while the patient is sleeping.

[0298] In certain forms of the present technology, a positioning and stabilising structure 3300 comprises a strap constructed to be breathable to allow moisture vapour to be transmitted through the strap,

[0299] In certain forms of the present technology, a system is provided comprising more than one positioning and stabilising structure 3300, each being configured to provide a retaining force to correspond to a different size and / or shape range. For example the system may comprise one form of positioning and stabilising structure 3300 suitable for a large sized head, but not a small sized head, and another, suitable for a small sized head, but not a large sized head.5.3.3.1 Conduit headgear5.3.3.1.1 Conduit headgear tubes

[0300] In some forms of the present technology, the positioning and stabilising structure 3300 comprises one or more headgear tubes 3350 that deliver pressurised air received from a conduit forming part of the air circuit 4170 from the RPT device to the patient’s airways, for example through the plenum chamber 3200 and seal-forming structure 3100. In the form of the present technology illustrated in Fig. 3Z, the positioning and stabilising structure 3300 comprises two tubes 3350 that deliver air to the plenum chamber 3200 from the air circuit 4170. The tubes 3350 are configured to position and stabilise the seal-forming structure 3100 of the patient interface 3000 at the appropriate part of the patient’s face (for example, the nose and / or mouth) in use. This allows the conduit of air circuit 4170 providing the flow of pressurised air to connect to a connection port 3600 of the patient interface in a position other than in front of the patient’s face, for example on top of the patient’s head.

[0301] In the form of the present technology illustrated in Fig. 3Z, the positioning and stabilising structure 3300 comprises two tubes 3350, each tube 3350 being positioned in use on a different side of the patient’s head and extending across the respective cheek region, above the respective ear (superior to the otobasion superior on the patient’s head) to the elbow 3610 on top of the head of the patient 1000. This form of technology may be advantageous because, if a patient sleeps with their head on its side and one of the tubes 3350 is compressed to block or partially block the flow of gas along the tube 3350, the other tube 3350 remains open to supply pressurised gas to the patient. In other examples of the technology, the patient interface 3000 may comprise a different number of tubes, for example one tube, or two or more tubes.

[0302] In one example in which the patient interface has one tube 3350, the single tube 3350 is positioned on one side of the patient’s head in use (e.g. across one cheek region) and a strap forms part of the positioning and stabilising structure 3300 and is positioned on the other side of the patient’s head in use (e.g. across the other region) to assist in securing the patient interface 3000 on the patient’s head. For example, the tube 3350 and the strap may each be under tension in use in order to assist in maintaining the seal-forming structure 3100 in a sealing position.

[0303] In one form, the tube 3350 may be at least partially extensible so that the tube 3350 and the strap may adjust substantially equal lengths when worn by a patient. This may allow for substantially symmetrical adjustments between the tube 3350 and the strap so that the seal-forming structure remains substantially in the middle.

[0304] In the form of the technology shown in Fig. 3Z, the two tubes 3350 are fluidly connected at superior ends to each other and to the connection port 3600. In some examples, the two tubes 3350 are integrally formed while in other examples the tubes 3350 are formed separately but are connected in use and may be disconnected, for example for cleaning or storage. Where separate tubes are used, they may be indirectly connected together, for example each may be connected to a T-shaped connector. The T-shaped connector may have two arms / branches each fluidly connectable to a respective one of the tubes 3350. Additionally, the T-shaped connector may have a third arm or opening providing the connection port 3600 for fluid connection to the air circuit 4170 in use. The opening may be an inlet 3332 (see e.g., 7C) for receiving the flow of pressurized air.

[0305] In some forms, the third arm of the T-shaped connector may be substantially perpendicular to each of the first two arms.

[0306] In some forms, the third arm of the T-shaped connector may be obliquely formed with respect to each of the first two arms.

[0307] In some forms, a Y-shaped connector may be used instead of the T-shaped connector. The first two arms may be oblique with respect to one another, and the third arm may be oblique with respect to the first two arms. The angled formation of the first two arms may be similar to the shape of the patient’s head in order to conform to the shape.

[0308] In some forms, at least one of the arms of the T-shaped connector (or Y- shaped connector) may be flexible. This may allow the connector to bend based on theshape of the patient’s head and / or a force in the positioning and stabilising structure 3300.

[0309] In some forms, at least one of the arms of the T-shaped connector (or Y- shaped connector) may be at least partially rigidised. This may assist in maintaining the shape of the connector so that bending of the connector does not close the airflow path.

[0310] The tubes 3350 may be formed from a flexible material, such as an elastomer, e.g. silicone or TPE, and / or from one or more textile and / or foam materials. The tubes 3350 may have a preformed shape and may be able to be bent or moved into another shape upon application of a force but may return to the original preformed shape in the absence of said force. The tubes 3350 may be generally arcuate or curved in a shape approximating the contours of a patient’s head between the top of the head and the nasal or oral region.

[0311] In some examples, the one or more tubes 3350 are crush resistant to resist being blocked if crushed during use, for example if squashed between a patient’s head and pillow, especially if there is only one tube 3350. The tubes 3350 may be formed with a sufficient structural stiffness to resist crushing or may be as described in US Patent No. 6,044,844, the contents of which are incorporated herein by reference.

[0312] Each tube 3350 may be configured to receive a flow of air from the connection port 3600 on top of the patient’s head and to deliver the flow of air to the seal-forming structure 3100 at the entrance of the patient’s airways. In the example shown in Fig. 3Z, each tube 3350 lies in use on a path extending from the plenum chamber 3200 across the patient’s cheek region and superior to the patient’s ear to the elbow 3610. For example, a portion of each tube 3350 proximate the plenum chamber 3200 may overlie a maxilla region of the patient’s head in use. Another portion of each tube 3350 may overlie a region of the patient’s head superior to an otobasion superior of the patient’s head. Each of the tubes 3350 may also lie over the patient’s sphenoid bone and / or temporal bone and either or both of the patient’s frontal bone and parietal bone. The elbow 3610 may be located in use over the patient’s parietal bone, over the frontal bone and / or over the junction therebetween (e.g. the coronal suture).

[0313] In certain forms of the present technology the patient interface 3000 is configured such that the connection port 3600 can be positioned in a range of positions across the top of the patient’s head so that the patient interface 3000 can be positionedas appropriate for the comfort or fit of an individual patient. In some examples, the headgear tubes 3350 are configured to allow movement of an upper portion of the patient interface 3000 (e.g. a connection port 3600) with respect to a lower portion of the patient interface 3000 (e.g. a plenum chamber 3200). That is, the connection port 3600 may be at least partially decoupled from the plenum chamber 3200. In this way, the seal -forming structure 3100 may form an effective seal with the patient’s face irrespective of the position of the connection port 3600 (at least within a predetermined range of positions) on the patient’s head.

[0314] As described above, in some examples of the present technology the patient interface 3000 comprises a seal-forming structure 3100 in the form of a cradle cushion which lies generally under the nose and seals to an inferior periphery of the nose (e.g. an under-the-nose cushion). The positioning and stabilising structure 3300, including the tubes 3350 may be structured and arranged to pull the seal-forming structure 3100 into the patient’s face under the nose with a sealing force in a posterior and superior direction (e.g. a posterosuperior direction). A sealing force with a posterosuperior direction may cause the seal -forming structure 3100 to form a good seal to both the inferior periphery of the patient’s nose and anterior-facing surfaces of the patient’s face, for example on either side of the patient’s nose and the patient’s lip superior.

[0315] Conduits forming part of the positioning and stabilising structure 3300, like headgear straps, may provide a force that contributes to the positioning and stabilising force FPSS. As illustrated in Fig. 3Z-1, the positioning and stabilising force FPSS may be the resultant force from the various forces of the different elements of the positioning and stabilising structure 3300. For example, each conduit may provide a force Fconduit directed in the posterior and respective lateral direction in order to hold the seal -forming structure 3100 against the patient’s face (into the upper lip and sealing under the nose) and oppose the effect of the positive pressure in the plenum chamber 3200 to lift off the face (i.e., Fplenum). The force Fconduit directed may also be directed at least partially in the superior direction in order to overcome the gravitational force Fg.

[0316] In some forms, the conduits may provide a force directed into the patient’s head when the conduits are filled with pressurized air. The force may assist in gripping the patient’s head. The force may be caused by the inflation of the conduits duringnormal use. In some forms, the force may provide a cushioning effect to the patient’s head. The conduits may be designed in order to limit expansion in order to prevent over-gripping the patient’s head.

[0317] The position of the patient’s head may also change the gripping force of the conduits. For example, if the patient is sleeping on his side, the weight of the patient’s head may compress one conduit, and the other conduit (e.g., the lateral portion not between the patient’s head and a sleeping surface, like a pillow) may additionally expand in order to keep substantially the same flow rate of pressurized air.

[0318] The gravitational force Fg may be opposed by a frictional force Ff, which may act in a direction directly opposite of the gravitational force Fg. As gravity pulls the seal -forming structure 3100 and the plenum chamber 3200 in the inferior direction (as viewed in Fig. 3A-1), the frictional force Ff would act in the superior direction (e.g., against a patient’s face). For example, the patient may experience the frictional force Ff against his lip superior (and / or other surfaces of the patient’s face in contact with the seal-forming structure 3100) in order to oppose the motion in the inferior direction (which may help to stabilising the cushion in place). Although the frictional force Ff is shown specifically opposing the gravitational force Fg of the seal -forming structure 3100 and the plenum chamber 3200, components of an overall frictional force (not shown) would also oppose the gravitational force Fg associated with the positioning and stabilising structure 3300 and any other portions of the patient interface 3000. A force of friction can act along any place where the patient interface 3000 contacts the patient’s skin (or hair). The frictional force Ff extends in the opposite direction of the gravitational force Fg and along the patient’s skin (or hair).

[0319] In some forms, the sum of the various forces may equal zero so that the patient interface 3000 is at equilibrium (e.g., not moving along the patient’s face while in use). Specifically, the gravitational force Fg and the blowout force Fplenum tend to move the seal-forming structure 3100 away from the desired sealing position. The positioning and stabilising force FPSS is applied in order to counteract the gravitational force Fg and the blowout force Fplenum (as well as any frictional forces Ff) and keep the seal-forming structure 3100 properly situated. Although the positioning and stabilising force FPSS may exceed the sum of the gravitational force Fg and the blowout force Fplenum (with any additional positioning and stabilising force FPSS being balanced by reaction force from the patient’s head acting on theportions of patient interface 3000) and still maintain the seal-forming structure 3100 in an appropriate sealing position, patient comfort may be sacrificed. Maximum patient comfort may be achieved when the net force on the patient interface 3000 is zero and the positioning and stabilising force FPSS is exactly strong enough to achieve this. In some examples the positioning and stabilising structure 3300 may be adjustable such that when fitted the positioning and stabilising force FPSS is greater than required to exactly balance the gravitational force Fg and the blowout force Fplenum to hold the patient interface 3000 against the patient’s head tightly enough that disruptive forces which may be experienced in use (such as tube drag or lateral shunting of the plenum chamber 3200 during side sleeping) do not disrupt the seal. As described below, various positions of the patient’s head while using the patient interface 3000 may determine the positioning and stabilising force FPSS necessary to achieve equilibrium5.3.3.1.2 Extendable and non-extendable tube portions

[0320] In some examples of the present technology, one or both of the tubes 3350 are not extendable in length. However, in some forms, the tubes 3350 may comprise one or more extendable tube sections, for example formed by an extendable concertina structure. In some forms, the patient interface 3000 may comprise a positioning and stabilising structure 3300 including at least one gas delivery tube comprising a tube wall having an extendable concertina structure. The patient interface 3000 shown in Fig. 3Z comprises tubes 3350, the superior portions of which comprise extendable tube sections each in the form of an extendable concertina structure 3362.

[0321] In some forms, the extendable concertina structure 3328 may be formed as a series of ridges and grooves on the surface of the tubes 3350. The concertina structure 3328 may be biased toward a retracted position, and may move to an expanded position when the patient dons the positioning and stabilising structure 3300. Because portions of the tubes 3350 may be substantially inextensible (e.g., non- extendable tube sections 3363), the concertina structures 3328 permit the positioning and stabilising structure 3300 to stretch in order to fit different sized heads. This may allow a single sized tube 3350 to be used with multiple sized heads. For example, the positioning and stabilising structure 3300 may be “one-size-fits-all” as a result of the concertina structure 3328. Alternatively, the tubes 3350 may be manufactured in multiple sizes (e.g., small, medium, large). The patient may select a length that mostclosely conforms to their head, and the concertina structures 3328 may make small adjustments in order to tailor the fit to the individual patient.

[0322] In some forms, the inlet 3332 may be disposed in the middle of the conduit 6320. For example, the tubes 3350 may be symmetric about the inlet 3332 through at least one axis.

[0323] The cross-sectional shape of the non-extendable tube sections 3363 of the tubes 3350 may be circular, elliptical, oval, D-shaped or a rounded rectangle, for example as described in US Patent No. 6,044,844. A cross-sectional shape that presents a flattened surface of tube on the side that faces and contacts the patient’s face or other part of the head may be more comfortable to wear than, for example a tube with a circular cross-section.

[0324] In some examples of the present technology, the non-extendable tube sections 3363 connects to the plenum chamber 3200 from a low angle. The headgear tubes 3350 may extend inferiorly down the sides of the patient’s head and then curve anteriorly and medially to connect to the plenum chamber 3200 in front of the patient’s face. The tubes 3350, before connecting to the plenum chamber 3200, may extend to a location at the same vertical position as (or, in some examples, inferior to) the connection with the plenum chamber 3200. That is, the tubes 3350 may project in an at least partially superior direction before connecting with the plenum chamber 3200. A portion of the tubes 3350 may be located inferior to the plenum chamber 3200 and / or the seal forming structure 3100. The tubes 3350 may contact the patient’s face below the patient’s cheekbones, which may be more comfortable than contact on the patient’s cheekbones and may avoid excessively obscuring the patient’s peripheral vision.5.3.3.1.3 Conduit headgear connection port

[0325] In certain forms of the present technology, the patient interface 3000 may comprise a connection port 3600 located proximal to a superior, lateral or posterior portion of a patient’s head. For example, in the form of the present technology illustrated in Fig 3Z, the connection port 3600 is located on top of the patient’s head (e.g. at a superior location with respect to the patient’s head). In this example the patient interface 3000 comprises an elbow 3610 forming the connection port 3600. The elbow 3610 may be configured to fluidly connect with a conduit of an air circuit 4170. The elbow 3610 may be configured to swivel with respect to the positioning and stabilising structure 3300 to at least partially decouple the conduit from the positioningand stabilising structure 3300. In some examples the elbow 3610 may be configured to swivel by rotation about a substantially vertical axis and, in some particular examples, by rotation about two or more axes. In some examples the elbow may comprise or be connected to the tubes 3350 by a ball-and-socket joint. The connection portion 3600 may be located in the sagittal plane of the patient’s head in use.

[0326] Patient interfaces having a connection port that is not positioned anterior to the patient’s face may be advantageous as some patients may find a conduit that connects to a patient interface anterior to their face to be unsightly and / or obtrusive. For example, a conduit connecting to a patient interface anterior to the patient’s face may be prone to interference with bedclothes or bed linen, particularly if the conduit extends inferiorly from the patient interface in use. Forms of the present technology comprising a patient interface having a connection port positioned superiorly to the patient’s head in use may make it easier or more comfortable for a patient to lie or sleep in one or more of the following positions: a side-sleeping position, a supine position (e.g. on their back, facing generally upwards) or in a prone position (e.g. on their front, facing generally downwards). Moreover, connecting a conduit to an anterior portion of a patient interface may exacerbate a problem known as tube drag in which the conduit exerts an undesired force upon the patient interface during movement of the patient’s head or the conduit, thereby causing dislodgement away from the face. Tube drag may be less of a problem when force is received at a superior location of the patient’s head than anterior to the patient’s face proximate to the sealforming structure (where tube drag forces may be more likely to disrupt the seal).5.3.3.1.4 Headgear Tube Fluid Connections

[0327] The two tubes 3350 are fluidly connected at their inferior ends to the plenum chamber 3200. In certain forms of the technology, the connection between the tubes 3350 and the plenum chamber 3200 is achieved by connection of two rigid connectors. The tubes 3350 and plenum chamber 3200 may be configured to enable the patient to easily connect the two components together in a reliable manner. The tubes 3350 and plenum chamber 3200 may be configured to provide tactile and / or audible feedback in the form of a ‘re-assuring click’ or a similar sound, so that the patient may easily know that each tube 3350 has been correctly connected to the plenum chamber 3200. In one form, the tubes 3350 are formed from a silicone or textile material and the inferior end of each of the silicone tubes 3350 is overmolded to a rigid connectormade, for example, from polypropylene, polycarbonate, nylon or the like. The rigid connector on each tube 3350 may comprise a female mating feature configured to connect with a male mating feature on the plenum chamber 3200. Alternatively, the rigid connector on each tube 3350 may comprise a male mating feature configured to connect to a female mating feature on the plenum chamber 3200. In other examples the tubes 3350 may each comprise a male or female connector formed from a flexible material, such as silicone or TPE, for example the same material from which the tubes 3350 are formed.

[0328] In other examples a compression seal is used to connect each tube 3350 to the plenum chamber 3200. For example, a resiliently flexible (e.g. silicone) tube 3350 without a rigid connector may be configured to be squeezed to reduce its diameter so that it can be compressed into a port in the plenum chamber 3200 and the inherent resilience of the silicone pushes the tube 3350 outwards to seal the tube 3350 in the port in an air-tight manner. Alternatively, in a hard-to-hard type engagement between the tube 3350 and the plenum chamber 3200, each tube 3350 and / or plenum chamber 3200 may comprise a pressure activated seal, for example a peripheral sealing flange. When pressurised gas is supplied through the tubes 3350 the sealing flange may be urged against the join between the tubes and a circumferential surface around a port or connector of the plenum chamber 3200 to form or enhance a seal between the tube 3350 and plenum chamber 3200.5.3.3.2 Headgear straps

[0329] In some forms, the positioning and stabilising structure 3300 may include headgear 3302 with at least one strap which may be worn by the patient in order to assist in properly orienting the seal -forming structure 3100 against the patient’s face (e.g., in order to limit or prevent leaks).

[0330] As described above, some forms of the headgear 3302 may be constructed from a textile material, which may be comfortable against the patient’s skin. The textile may be flexible in order to conform to a variety of facial contours. Although the textile may include rigidisers along a selected length, which may limit bending, flexing, and / or stretching of the headgear 3302.

[0331] In certain forms, the headgear 3302 may be at least partially extensible. For example, the headgear 3302 may include elastic, or a similar extensible material. For example, the entire headgear 3302 may be extensible or selected portions may beextensible (or more extensible than surrounding portions). This may allow the headgear 3302 to stretch while under tension, which may assist in providing a sealing force for the seal -forming structure 3100.

[0332] Two forms of the headgear, four-point headgear 3302-1 and two-point headgear 3302-2, are discussed in more detail below as illustrative examples.5.3.3.2.1 Four-point connection

[0333] As shown in Fig. 7E, some forms of the headgear 3302-1 may be a four- point connection headgear. This means that the headgear 3302-1 may connect to four separate places on the plenum chamber 3200, on a frame connected to the plenum chamber 3200, and / or on arms connected to the plenum chamber 3200. The headgear 3302-1 may include four different straps providing a tensile force to help maintain the seal-forming structure 3100 in a sealing position. The positioning and stabilising structure 3300 of Fig. 3 A may also be considered a four-point connection headgear.

[0334] In some forms, the headgear 3302-1 may include inferior straps 3304-1, which may connect to an inferior portion of the cushion 3050-1. The inferior straps3304-1 may extend along the patient’s cheek toward a posterior region of the patient’s head. For example, the inferior straps 3304-1 may overlay the masseter muscle on either side of the patient’s face. The inferior straps 3304-1 may therefore contact the patient’s head below the patient’s ears. The inferior straps 3304-1 may meet at the posterior of the patient’s head, and may overlay the occipital bone and / or the trapezius muscle.

[0335] The headgear 3302-1 may also include superior straps 3305-1, which may overlay the temporal bones, parietal bone, and / or occipital bone. The superior straps3305-1 may also connect to the tubes 3350 (e.g., by interfacing with the tabs 3320).

[0336] A rear strap 3307-1 may extend between the superior straps 3305-1 and between the inferior straps 3304-1. The inferior and superior straps 3304-1, 3305-1 on a given side (e.g., left or right) may also be connected to the rear strap 3307-1 adjacent to one another. The height of the rear strap 3307-1 may therefore be approximately the combined height of the inferior and superior strap 3304-1, 3305-1. The rear strap 3307- 1 may overlay the occipital bone and / or the pariental bone in use. This may allow the rear strap 3307-1 to assist in anchoring the headgear 3302-1 to the patient’s head.

[0337] In the illustrated example, the headgear 3302-1 may be formed with a substantially X-shape. The inferior and superior straps 3304-1, 3305-1 may beconnected to a rear strap 3307-1 using stitching, ultrasonic welding, or any similar process.

[0338] In some forms, the inferior straps 3304-1 are connected to a magnetic member 3306-1. For example, each inferior straps 3304-1 may be threaded through a magnetic member 3306-1, so that a length of each inferior strap 3304-1 may be adjusted. The magnetic members 3306-1 may removably connect to the magnets 3370- 1 (described below), so that the inferior straps 3304-1 may be disconnected from the plenum chamber 3200, but the length of the inferior straps 3304-1 may not be affected.

[0339] In some forms, the superior straps 3305-1 may be connected directly to the tabs 3320 of the tubes 3350. The superior straps 3305-1 may be threaded through the tabs 3320 in order to adjust the length and control the tensile force of each superior strap 3305-1.

[0340] In some forms, the headgear 3302-1 may be used only with the nose and mouth cushion 3050-1 (e.g., because the nose-only cushion 3050-1 does not have four connection points). However, the headgear 3302-1 may be used interchangeably with the tubes 3350 and the rigidiser arms 3340.5.3.3.2.2 Two-point connection

[0341] As shown in Fig. 7F, some forms of the headgear 3302-2 may be a two- point connection headgear. This means that the headgear 3302-2 may connect to two separate places.

[0342] In some forms, the headgear 3302-2 may be formed from a continuous piece of material. In other words, the headgear 3302-2 may not be formed from multiple straps connected (e.g., stitched) together. This may be comfortable for a patient as they will not be in contact with any seams or joints connecting different straps. In other forms, the headgear 3302-2 may be formed from multiple straps (e.g., two superior straps, a rear strap, etc.) that are connected together (e.g., with stitching, ultra-sonic welding, etc.).

[0343] In certain forms of the present technology, the positioning and stabilising structure 3300 comprises at least one headgear strap acting in addition to the tubes 3350 to position and stabilise the seal-forming structure 3100 at the entrance to the patient’s airways. As shown in Fig. 3Z, the patient interface 3000 comprises a strap 3307-2 forming part of the positioning and stabilising structure 3300. The strap 3307-2 may be known as a back strap or a rear headgear strap, for example. The rear strap3307-2 may overlay the temporal bones, parietal bone, and / or occipital bone. In other examples of the present technology, one or more further straps may be provided. For example, patient interfaces 3000 according to examples of the present technology having a nose-and-mouth cushion may have a second, lower, strap configured to lie against the patient’s head proximate the patient’s neck and / or against posterior surfaces of the patient’s neck.

[0344] In the example shown in Fig. 3Z, strap 3310 of the positioning and stabilising structure 3300 is connected between the two tubes 3350 positioned on each side of the patient’s head and passing around the back of the patient’s head, for example overlying or lying inferior to the occipital bone of the patient’s head in use. The strap 3310 connects to each tube above the patient’s ears. With reference to Fig. 3Z, the positioning and stabilising structure 3300 comprises a pair of tabs 3320. In use a strap 3310 may be connected between the tabs 3320. The strap 3310 may be sufficiently flexible to pass around the back of the patient’s head and lie comfortably against the patient’s head, even when under tension in use.

[0345] As shown in Fig. 7F, some forms of the headgear 3302-2 may be at least partially bifurcated. For example, a rear strap 3307-2 of the headgear 3302-2 (e.g., configured to contact the posterior portion of the patient’s head) may be wider than the surrounding portions of the headgear 3302-2. An intermediate section 3308-2 of the rear strap 3307-2 may include a slit 3309-2. A superior section of the rear strap 3307-2 may therefore be movable relative to the inferior section as a result of the slit 3309-2. This may allow the patient to have a larger strap coverage on the posterior region of their head, which may assist in better anchoring the headgear 3302-2 to the patient’s head since there is no inferior strap (e.g., 3304-1).

[0346] In some forms, the headgear 3302-2 may be used only with the nasal cushion 3050-2 (e.g., because the nose and mouth cushion 3050-1 does not have four connection points). However, the headgear 3302-2 may be used interchangeably with the tubes 3350 and the rigidiser arms 3340.5.3.3.3 Rigidiser Arm

[0347] As shown in Fig. 7D, a rigidiser arm 3340 may be an elongated, rigid member that assists in maintaining the cushion (e.g., the nose and mouth cushion 3050- 1 or the nasal cushion 3050-2) in an operating position. The rigidiser arm 3340 maycontact a side of the patient’s head and provide a force to limit slipping of the sealforming structure 3100 from the patient’s nose and / or mouth.

[0348] In some forms, the rigidiser arm 3340 is constructed from a rigid material (e.g., plastic). The rigid material may not permit the rigidiser arm 3340 to stretch. Additionally, the rigidiser arm 3340 may be substantially inflexible and may be unable to bend. The rigidiser arm 3340 may be pre-molded into a desired shape in order to fit a patient’s head. For example, the rigidiser arms 3340 may be molded with a curved shape to substantially correspond to the shape of the side of the patient’s head (e.g., overlaying the masseter muscle and / or the temporal bone).

[0349] In certain forms, the rigidiser arm 3340 may be molded in order to conform to a specific patient’s head (e.g., the rigidiser arm 3340 is customized).

[0350] In some forms, the rigidiser arm 3340 may be flexible along at least one direction. For example, the rigidiser arm 3340 may be flexible about its width and may be inflexible along its length. In other words, the rigidiser arm 3340 may be bendable about an axis along the width of the rigidiser arm 3340, but may be unable to bend about an axis perpendicular to the rigidiser arm 3340. This may allow an individual patient to adjust the rigidiser arm 3340 in order to better fit their individual head.

[0351] In certain forms, the rigidiser arm 3340 may remain in the new position after being bent. This may allow a patient adjust the shape of the rigidiser arm 3340 for their specific head and then the rigidiser arm 3340 will keep the desired shape while in use in order to promote patient comfort.

[0352] In some forms, a first end 3342 of the rigidiser arm 3340 may be a free end and a second end 3344 (e.g., opposite of the first end 3342) of the rigidiser arm 3340 may be fixed. The first end 3342 may be curved in order to minimize sharp edges that could cause patient discomfort. The first end 3342 may also overlay the patient’s head proximate to the temporal bone, in use. The second end 3344 may be fixed to an arm connection structure 3504.

[0353] In some forms, the arm connection structure 3504 may be similar to the conduit connection structure 3500. For example, the arm connection structure 3504 and the conduit connection structure 3500 may have substantially the same shape. This may allow either the conduit connection structure 3500 or the arm connection structure 3504 to fit into the groove (e.g., 3266-1 or 3266-2) and connect to the plenum chamber inlet port 3254. The arm connection structure 3504 may connect to the nose and mouthcushion 3050-1 or the nose-only cushion 3050-2 in substantially the same way as the conduit connection structure 3500 (e.g., via a snap fit, press fit, friction fit, etc.).

[0354] In some forms, the arm connection structure 3504 may act as a plug for the plenum chamber inlet port 3254 (e.g., either 3254-1 and / or 3254-2). Unlike the tubes 3350, the rigidiser arm 3340 does not convey pressurized air to the plenum chamber 3200. The rigidised arm 3340 may be used with a “tube down” configuration, where a hose is connected to the vent opening 3402 (e.g., either 3402-1 and / or 3402-2), and conveys air into the plenum chamber 3200 through the vent opening 3402. In this example, air does not need to travel into or out of the plenum chamber inlet openings 3254. Thus, the arm connection structure 3504 may form a seal with the plenum chamber inlet opening 3254 in order to limit airflow into or out of the plenum chamber 3200.5.3.4 Vent

[0355] In one form, the patient interface 3000 includes a vent 3400 constructed and arranged to allow for the washout of exhaled gases, e.g. carbon dioxide.

[0356] 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.

[0357] One form of vent 3400 in accordance with the present technology comprises a plurality of holes, for example, about 20 to about 80 holes, or about 40 to about 60 holes, or about 45 to about 55 holes.

[0358] The vent 3400 may be located in the plenum chamber 3200. Alternatively, the vent 3400 is located in a decoupling structure, e.g., a swivel.

[0359] As shown in Fig. 7N, a vent 3450 may be used with the patient interface 3000. The vent 3450 may have a substantially similar shape to the vent opening 3402-1 (e.g., a substantially circular shape).

[0360] The vent 3450 may be used with either the mouth and nose plenum chamber 3200-1 (e.g., illustrated in Figs. 7A) or the nose-only plenum chamber 3200-2 (e.g., illustrated in Figs. 7B).

[0361] With continued reference to Fig. 7A, the vent 3450 may include a vent housing 3404, which may be configured to engage with the vent opening 3402. The vent housing 3404 may be constructed from a rigid material or a semi-rigid material. For example, the vent housing 3404 may be constructed from plastic, metal, or any similar material. The vent housing 3404 may add rigidity to the patient interface 3000 (e.g., to limit unwanted bending that may affect the position of the seal-forming structure 3100 on the patient’s face).

[0362] The vent housing 3404 may include an anterior surface 3408, a posterior surface 3412, and a groove 3416. The anterior surface 3408 faces away from the patient’s face in use, and may be positioned outside the pressurized volume of the plenum chamber 3200. The posterior surface 3412 is disposed opposite to the anterior surface 3408. In use, the posterior surface 3412 may face the patient and may be disposed within the pressurized volume of the plenum chamber 3200. The groove 3416 may be formed between the anterior and posterior surfaces 3408, 3412. A portion of the plenum chamber 3200 may be received within the groove 3416 in order to retain the vent 3400 in position.

[0363] In some forms, a diffuser 3448 may be used with the vent housing 3404. The diffuser 3448 may assist with limiting the decibel output from any of the patient interface 3000 (or any other patient interface). Specifically, the diffuser 3448 may assist in limiting the decibel level associated with air output from the patient interface 3000 (e.g., exhaled air), although the diffuser 3448 may limit the decibel level of at any point in the patient interface.

[0364] In certain forms, the diffuser 3448 may diffuse, and therefore slow, the exhaust gas exiting the plenum chamber 3200 and passing through the vent housing 3404. The diffuser 3448 may assist in avoiding jetting and associated discomfort to the patient and / or bed partner (e.g., noise caused by jetting against a pillow, sheets, bedclothes, etc.).

[0365] In some forms, the diffuser may include an anterior surface 3456 that faces away from the patient in use. An outer diameter of the anterior surface 3456 may be less than an inner diameter of the vent housing 3404 proximate to the anterior surface 3408. This may form a gap 3464 through which air may travel.5.3.5 Decoupling structure(s)

[0366] In one form the patient interface 3000 includes at least one decoupling structure, for example, a swivel or a ball and socket.5.3.6 Connection port

[0367] Connection port 3600 allows for connection to the air circuit 4170.5.3.7 Forehead support

[0368] In one form, the patient interface 3000 includes a forehead support 3700.5.3.8 Anti-asphyxia valve

[0369] In one form, the patient interface 3000 includes an anti-asphyxia valve.5.3.9 Ports

[0370] In one form of the present technology, a patient interface 3000 includes one or more ports that allow access to the volume within the plenum chamber 3200. In one form this allows a clinician to supply supplementary oxygen. In one form, this allows for the direct measurement of a property of gases within the plenum chamber 3200, such as the pressure.5.3.10 Modularity

[0371] As described above, the cushion, headgear, and sleeves may come in different styles, which may correspond to different uses (e.g., mouth breathing, nasal breathing, etc.). A patient or clinician may select certain combinations of cushions, headgear, and sleeves in order to optimize the effectiveness of the therapy and / or the individual patient’s comfort. An example of this sort of modular design is described in PCT / SG2022 / 050777 filed 28 October 2022, incorporated herein by reference in its entirety.

[0372] In some forms, the different styles of cushions, headgear, and sleeves may be used interchangeably with one another in order to form different combinations of patient interfaces. This may be beneficial from a manufacturing prospective because wider variety of patient interfaces may be created using fewer parts. Additionally or alternatively, the various combinations may allow a patient to change styles of patient interface without changing the every component.

[0373] Air may be delivered to the patient in one of two main ways. In one example, the patient may receive the flow of pressurized air through headgear tubes 3350 (see e.g., Fig. 3Z). This may be referred to as a “tube up” configuration and may position a connection port at the top of the patient’s head. In other example, the patientmay receive the flow of pressurized air through a conduit connected to the plenum chamber 3200, for example through the connection port 3600 (see e.g., Fig. 3A). This may be referred to a “tube down” configuration where the airflow conduit is positioned in front of the patient’s face. Different patients may be more comfortable with one style of air delivery over the other (e.g., because of the patient’s sleep style). Therefore, it may be beneficial to allow a single style of patient interface to be used in either the “tube up” or “tube down” configuration.

[0374] The patient interface may be part of a modular assembly with a variety of interchangeable components that may be swapped out by a patient and / or clinician for one or more components for a different style. The following description describes the various combinations that may be created by assembling the different components together.5.3.10.1 Sleeve

[0375] In some forms, to allow for modularity, a sleeve may be used with the tubes 3350 and / or the rigidisier arms 3340. The sleeve may at least partially surround the tubes 3350 and / or the rigidiser arms 3340. As shown in Figs. 7G to 71, different shapes of sleeves may be used, which may correspond to different types of positioning and stabilising structures 3300. In some forms, the configuration of the sleeve may be customized to fit a particular user’s face. For instance, the sleeves may be configured in a relatively more posterior region of the patient’ s head.

[0376] In some forms, the sleeve may be constructed from a comfortable material. For example, the sleeve may be constructed from a textile material, a foam material, or a combination of the two. The comfortable material may contact the patient in use, and may feel soft against the patient’s skin in order to improve patient compliance.

[0377] The material may also be flexible in order to assist in donning or doffing the sleeve from the tube 3350 or the rigidiser arms 3340. For example, the material may allow the sleeve to bend in order to conform to the shape of the tubes or conduit headgear 3350 or the rigidiser arms 3340, which may change depending on the shape of an individual patient’s head.

[0378] In some forms, the sleeve may also be at least partially elastic (e.g., the material may allow the sleeve to stretch). The elastic material may help the sleeve stretch in order to fit around the tubes 3350 or the rigidiser arms 3340. The elasticmaterial may then return to an initial position that is snug against the tubes 3350 or the rigidiser arms 3340 in order to limit the sleeve from sliding while in use.

[0379] As described in more detail below, some forms of the sleeves may be specific to a rigidising element (e.g., tubes 3350 and / or rigidiser arms 3340). However, the sleeves may assist the rigidising elements in connecting interchangeably with the version or styles of cushions (e.g., the mouth and nose cushion 3050-1, the nose-only cushion 3050-2, etc.).5.3.10.1.1 Conduit Sleeve

[0380] As shown in Fig. 7G, one example of a sleeve is a conduit sleeve 3351, which may be usable with the tubes 3350 described above.

[0381] As shown in Fig. 7G, the conduit sleeve 3351 may include a curved shape that may be similar to the shape of the tubes 3350 shown in Fig. 7C. The flexible material used to construct the conduit sleeve 3351 may allow the conduit sleeve 3351 to further curve in order to correspond to the shape of the tubes 3350 (e.g., when worn by the patient).

[0382] In some forms, the conduit sleeve 3351 may include a first or superior opening 3352. The superior opening 3352 may be disposed at one end of the conduit sleeve 3351. The superior opening 3352 may be an opening to a passage that extends along at least a portion of the conduit sleeve 3351.

[0383] As shown in Fig. 7G, some forms of the conduit sleeve 3351 may also include an inferior extension 3354. The inferior extension 3354 may be positioned on an opposite end of the conduit sleeve 3351 from the superior opening 3352. The conduit sleeve 3351 may be customized to fit a particular user’s face. For instance, the inferior extension 3354 of the conduit sleeve 3351 may be configured in a relatively more posterior region or anterior region of the patient’s head.

[0384] Some forms of the inferior extension 3354 may include a rigid or semirigid piece (e.g., within the sleeve 3351). The rigid or semi-rigid piece may be constructed from a plastic material, or a similar material. Alternatively, the inferior extension 3354 may be stiffened using a manufacturing process (e.g., stitching rigidised thread, flat knitting, using thicker material).

[0385] As shown in Fig. 7G, some forms of the inferior extension 3354 may include a connection member 3356. In the illustrated example, the connection member 3356 may be a magnet, although in other examples, the connection member 3356 maybe a different type of connector (e.g., a mechanical fastener, an adhesive, hook and loop material, etc.). The connection member 3356 may also be positioned at an end of the inferior extension 3354, although the connection member 3356 could alternatively be positioned anywhere along the inferior extension 3354.

[0386] In some forms, the connection member 3356 (e.g., a magnet) may be removably connected to the magnets 3370-1 of the headgear 3302-1. For example, when the conduit sleeves 3351 are connected to the tubes 3350 (see e.g., Fig. 7J), the magnets 3370-1 connected to the inferior straps 3304-1 may be removably connected to the connection member 3356 in order to provide the tensile force.5.3.10.1.2 Four-point arm sleeve

[0387] As shown in Fig. 7H, another example of a sleeve is a four-point arm sleeve 3380, which may be usable with the rigidiser arms 3340 described above.

[0388] As shown in Fig. 7H, the four-point arm sleeve 3380 may include a curved shape that may be similar to the shape of the rigidiser arm 3340 shown in Fig. 7D. The flexible material used to construct the four-point arm sleeve 3380 may allow the four- point arm sleeve 3380 to further curve in order to correspond to the shape of the rigidiser arm 3340 (e.g., when worn by the patient and / or went bent by the patient).

[0389] As shown in Fig. 7H, some forms of the four-point arm sleeve 3380 may include an inferior extension 3384. The inferior extension 3384 may be positioned at an end of the four-point arm sleeve 3380.

[0390] In the illustrated example, the shape and / or structure of the inferior extension 3384 is substantially the same as the shape of the inferior extension 3354.For example, the inferior extension 3384 may be more rigid as compared to the rest of the four-point arm sleeve 3380 (e.g., as a result of rigidising thread or rigid material).

[0391] As shown in Fig. 7H, some forms of the inferior extension 3384 may include a connection member 3386. In the illustrated example, the connection member 3386 may be a magnet, although in other examples, the connection member 3386 may be a different type of connector (e.g., a mechanical fastener, an adhesive, hook and loop material, etc.). The connection member 3386 may also be positioned at an end of the inferior extension 3384, although the connection member 3386 could alternatively be positioned anywhere along the inferior extension 3384.

[0392] In some forms, the connection member 3386 (e.g., a magnet) may be removably connected to the magnets 3370-1 of the headgear 3302-1. For example,when the four-point arm sleeves 3380 are connected to the rigidiser arm 3340 (see e.g., Fig. 7K), the magnets 3370-1 connected to the inferior straps 3304-1 may be removably connected to the connection member 3386 in order to provide the tensile force.

[0393] As shown in Fig. 7H, the four-point arm sleeve 3380 may include a pair of tabs 3394, which may be similar to the tab 3320 on the tubes 3350. When the four- point arm sleeve 3380 is worn by the patient, the tabs 3394 may be positioned in substantially the same place on the patient’s head as where the tabs 3320 are positioned when the patient wears the tubes 3350.5.3.10.1.3 Two-point arm sleeve

[0394] As shown in Fig. 71, yet another example of a sleeve is a two-point arm sleeve 3380-1, which may be usable with the rigidiser arms 3340 described above.

[0395] In some forms, the two-point arm sleeve 3380-1 may be similar to the four- point arm sleeve 3380 described above. Only some similarities and differences may be described below.

[0396] As shown in Fig. 71, the two-point arm sleeve 3380-1 may include an inferior opening 3388-1 that is positioned at an end of the two-point arm sleeve 3380- 1. The inferior opening 3388-1 may form an opening to a passageway through the two- point arm sleeve 3380-1. In the illustrated example, the inferior opening 3388-1 may open into a surface of the conduit sleeve 3380-1.

[0397] As shown in Fig. 71, the two-point arm sleeve 3380-1 may include a pair of tabs 3394-1, which may be similar to the tab 3320 on the tubes 3350. When the two- point arm sleeve 3380-1 is worn by the patient, the tabs 3394-1 may be positioned in substantially the same place on the patient’s head as where the tabs 3320 are positioned when the patient wears the tubes 3350.5.3.10.2 Assembled Patient Interfaces

[0398] As illustrated in Figs. 7J to 7M, the various elements described above may be combined into four different patient interfaces. The different patient interfaces may allow patients to use different styles based on their individual comfort. The modularity of the different elements (e.g., the ability to be used in multiple styles of patient interfaces) may simplify manufacturing and / or may allow a patient to more easily switch between styles of patient interfaces.5.3.10.2.1 Nose and Mouth Mask Tube Up Configuration

[0399] As illustrated in Fig. 7J, the patient may wear the cushion 3050-1 in a tube- up configuration with the tubes 3350 and the four-point headgear 3302-1. This assembly may form a tube up nose and mouth patient interface 3000-1.

[0400] In some forms, a conduit sleeve may be used with the tubes 3350 in order to enable a patient to experience the “tube up” air delivery style with the mouth and nose cushion 3050-1. As is described below, the conduit sleeve provides additional connection locations for connecting the four-point headgear 3302-1. However, other forms of connectors aside from or in addition to the conduit sleeve may be used.

[0401] In the illustrated example, the conduit sleeves may be connected to the tubes 3350 of the positioning and stabilising structure 3300. The tubes 3350 (via the conduit connection structure 3500), may be used to connect the tubes 3350 to the cushion 3050-1. The conduit sleeves provide the magnets in order to connect to the magnets 3370-1 (see e.g., Fig. 7E) of the four-point headgear 3302-1. Alternatively, a different connection form may be used.

[0402] As illustrated in Fig. 7J, the four-point headgear 3302-1 may connect in four separate locations in order to provide a tensile force that maintains the cushion 3050-1 in a sealing position on the patient’s head.

[0403] For example, the inferior straps 3304-1 (e.g., via the magnetic members 3306-1) may removably connect to the magnets of the conduit sleeves. In use, each inferior strap 3304-1 may contact the patient’s cheek (e.g., overlaying the masseter muscle). The inferior straps 3304-1 may also extend below the patient’s ears.5.3.10.2.2 Nose and Mouth Mask Tube Down Configuration

[0404] As illustrated in Fig. 7K, the patient may wear the cushion 3050-1 in a tube-down configuration with the rigidiser arms 3340 and the four-point headgear 3302-1. This assembly may form a tube down nose and mouth patient interface 3000-2.

[0405] In some forms, a conduit sleeve may be used with the rigidiser arms 3340 in order to enable a patient to experience the “tube down” air delivery style with the mouth and nose cushion 3050-1. As is described below, the conduit sleeve provides additional connection locations for connecting the four-point headgear 3302-1.However, other forms of connectors aside from or in addition to the conduit sleeve may be used.

[0406] In the illustrated example, the conduit sleeves may be connected to the rigidiser arms 3340 of the positioning and stabilising structure 3300. The rigidiser arms 3340 (via the conduit connection structure 3504), may be used to connect the rigidiser arms 3340 to the cushion 3050-1. The conduit sleeves provide the magnets in order to connect to the magnets 3370-1 (see e.g., Fig. 7E) of the four-point headgear 3302-1. Alternatively, a different connection form may be used.

[0407] As illustrated in Fig. 7K, the four-point headgear 3302-1 may connect in four separate locations in order to provide a tensile force that maintains the cushion 3050-1 in a sealing position on the patient’s head.

[0408] For example, the inferior straps 3304-1 (e.g., via the magnetic members 3306-1) may removably connect to the magnets of the conduit sleeves. In use, each inferior strap 3304-1 may contact the patient’s cheek (e.g., overlaying the masseter muscle). The inferior straps 3304-1 may also extend below the patient’s ears.5.3.10.2.3 Nose Mask Tube Up Configuration

[0409] As illustrated in Fig. 7L, the patient may wear the cushion 3050-2 in a tube-up configuration with the tubes 3350 and the two-point headgear 3302-2. This assembly may form a tube up nose only patient interface 3000-3

[0410] A conduit sleeve may be used with the tubes 3350, and may provide additional comfort to the patient. The sleeve may not add additional connection points to connect the positioning and stabilising structure 3300 on the cushion 3050-2. In the illustrated example, the tubes 3350 of the positioning and stabilising structure 3300 may be connected directly to the cushion 3050-2.

[0411] As illustrated in Fig. 7L, the two-point headgear 3302-2 may connect to the tabs 3320 on the tubes 3350 in order to provide a tensile force that maintains the cushion 3050-2 in a sealing position on the patient’s head.5.3.10.2.4 Nose Mask Tube Down Configuration

[0412] As illustrated in Fig. 7M, the patient may wear the cushion 3050-2 in a tube-up configuration with the rigidiser arms 3340 and the two-point headgear 3302-2. This assembly may form a tube down nose only patient interface 3000-4.

[0413] A conduit sleeve may be used with the rigidiser arms 3340, and may provide additional comfort to the patient. The sleeve may not add additional connection points to connect the positioning and stabilising structure 3300 on thecushion 3050-2. In the illustrated example, the rigidiser arms 3340 of the positioning and stabilising structure 3300 may be connected directly to the cushion 3050-2.

[0414] As illustrated in Fig. 7M, the two-point headgear 3302-2 may connect to the tabs 3320 on the sleeve in order to provide a tensile force that maintains the cushion 3050-2 in a sealing position on the patient’s head.5.3.10.2.5 Modularity of Elements

[0415] Fig. 7P illustrates how the different elements can be combined in order to form the four different patient interfaces described above. As illustrated, the different components may be reused for different styles of patient interfaces. This may allow for easier manufacturing and assembly, because a large number of the same components may be produced and used in a variety of styles. The only components not used in multiple styles may be the sleeves. However, the sleeves may be easier to manufacture. Fig. 70 shows a portion of air circuit 4170 that may interface with the patient interface, while Fig. 7N shows a vent 3404 that may interchangeably replace the air circuit shown in Fig. 70, depending on the style of the patient interface.5.4 RPT DEVICE

[0416] 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 4300, 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.

[0417] In one form, the RPT device 4000 is constructed and arranged to be capable of delivering a flow of air in a range of -20 L / min to +150 L / min while maintaining a positive pressure of at least 4 cmH20, or at least 10cmH2O, or at least 20 cmH20.

[0418] The RPT device may have an external housing 4010, formed in two parts, an upper portion 4012 and a lower portion 4014. Furthermore, the external housing 4010 may include one or more panel(s) 4015. The RPT device 4000 comprises a chassis 4016 that supports one or more internal components of the RPT device 4000. The RPT device 4000 may include a handle 4018.

[0419] The pneumatic path of the RPT device 4000 may comprise one or more air path items, e.g., an inlet air filter 4112, an inlet muffler 4122, a pressure generator4140 capable of supplying air at positive pressure (e.g., a blower 4142), an outlet muffler 4124 and one or more transducers 4270, such as pressure sensors 4272 and flow rate sensors 4274.

[0420] One or more of the air path items may be located within a removable unitary structure which will be referred to as a pneumatic block 4020. The pneumatic block 4020 may be located within the external housing 4010. In one form a pneumatic block 4020 is supported by, or formed as part of the chassis 4016.5.4.1 RPT device mechanical & pneumatic components

[0421] An RPT device may comprise one or more of the following components in an integral unit. In an alternative form, one or more of the following components may be located as respective separate units.5.4.1.1 Air filter (s)

[0422] An RPT device in accordance with one form of the present technology may include an air filter 4110, or a plurality of air filters 4110.

[0423] In one form illustrated in Fig. 4B, an inlet air filter 4112 is located at the beginning of the pneumatic path upstream of a pressure generator 4140.

[0424] In one form illustrated in Fig. 4B, an outlet air filter 4114, for example an antibacterial filter, is located between an outlet of the pneumatic block 4020 and a patient interface 3000 or 3800.5.4.1.2 Muffler(s)

[0425] An RPT device in accordance with one form of the present technology may include a muffler 4120, or a plurality of mufflers 4120.

[0426] In one form of the present technology (see e.g., Fig. 4B), an inlet muffler 4122 is located in the pneumatic path upstream of a pressure generator 4140.

[0427] In one form of the present technology, an outlet muffler 4124 is located in the pneumatic path between the pressure generator 4140 and a patient interface 3000 or 3800.5.4.1.3 Pressure generator

[0428] In one form of the present technology, a pressure generator 4140 for producing a flow, or a supply, of air at positive pressure is a controllable blower 4142. For example, the blower 4142 may include a brushless DC motor 4144 with one or more impellers. The impellers may be located in a volute. The blower may be capable of delivering a supply of air, for example at a rate of up to about 120 litres / minute, at apositive pressure in a range from about 4 cmH20 to about 20 cmH20, or in other forms up to about 30 cmH20 when delivering respiratory pressure therapy. The blower may be as described in any one of the following patents or patent applications the contents of which are incorporated herein by reference in their entirety: U.S. Patent No. 7,866,944; U.S. Patent No. 8,638,014; U.S. Patent No. 8,636,479; and PCT Patent Application Publication No. WO 2013 / 020167.

[0429] The pressure generator 4140 may be under the control of the therapy device controller 4240.

[0430] In other forms, a pressure generator 4140 may be a piston-driven pump, a pressure regulator connected to a high pressure source (e.g. compressed air reservoir), or a bellows.5.4.1.4 Transducer(s)

[0431] Transducers may be internal of the RPT device, or external of the RPT device. External transducers may be located for example on or form part of the air circuit, e.g., the patient interface. External transducers may be in the form of noncontact sensors such as a Doppler radar movement sensor that transmit or transfer data to the RPT device.

[0432] In one form of the present technology (see e.g., Fig. 4B), one or more transducers 4270 are located upstream and / or downstream of the pressure generator 4140. The one or more transducers 4270 may be constructed and arranged to generate signals representing properties of the flow of air such as a flow rate, a pressure or a temperature at that point in the pneumatic path.

[0433] In one form of the present technology, one or more transducers 4270 may be located proximate to the patient interface 3000 or 3800.

[0434] In one form, a signal from a transducer 4270 may be filtered, such as by low-pass, high-pass or band-pass filtering.5.5 AIR CIRCUIT

[0435] An air circuit 4170 in accordance with an aspect of the present technology is a conduit or a tube constructed and arranged to allow, in use, a flow of air to travel between two components such as RPT device 4000 and the patient interface 3000 or 3800.

[0436] In particular, the air circuit 4170 may be in fluid connection with the outlet of the pneumatic block 4020 and the patient interface. The air circuit may be referredto as an air delivery tube. In some cases there may be separate limbs of the circuit for inhalation and exhalation. In other cases a single limb is used.

[0437] In some forms, the air circuit 4170 may comprise one or more heating elements configured to heat air in the air circuit, for example to maintain or raise the temperature of the air. The heating element may be in a form of a heated wire circuit, and may comprise one or more transducers, such as temperature sensors. In one form, the heated wire circuit may be helically wound around the axis of the air circuit 4170. The heating element may be in communication with a controller. One example of an air circuit 4170 comprising a heated wire circuit is described in United States Patent 8,733,349, which is incorporated herewithin in its entirety by reference.5.6 HUMIDIFIER5.6.1 Humidifier overview

[0438] In one form of the present technology there is provided a humidifier 5000 (e.g. as shown in Fig. 5A) to change the absolute humidity of air or gas for delivery to a patient relative to ambient air. Typically, the humidifier 5000 is used to increase the absolute humidity and increase the temperature of the flow of air (relative to ambient air) before delivery to the patient’s airways.

[0439] The humidifier 5000 may comprise a humidifier reservoir 5110, a humidifier inlet 5002 to receive a flow of air, and a humidifier outlet 5004 to deliver a humidified flow of air. In some forms, as shown in Fig. 5A and Fig. 5B, an inlet and an outlet of the humidifier reservoir 5110 may be the humidifier inlet 5002 and the humidifier outlet 5004 respectively. The humidifier 5000 may further comprise a humidifier base 5006, which may be adapted to receive the humidifier reservoir 5110 and comprise a heating element 5240.5.7 BREATHING WAVEFORMS

[0440] Fig. 6 shows a model typical breath waveform of a person while sleeping. The horizontal axis is time, and the vertical axis is respiratory flow rate. While the parameter values may vary, a typical breath may have the following approximate values: tidal volume Vt 0.5L, inhalation time Ti 1.6s, peak inspiratory flow rate Qpeak 0.4 L / s, exhalation time Te 2.4s, peak expiratory flow rate Qpeak -0.5 L / s. The total duration of the breath, Tlol. is about 4s. The person typically breathes at a rate of about 15 breaths per minute (BPM), with Ventilation Vent about 7.5 L / min. A typical duty cycle, the ratio of Ti to Ttot, is about 40%.5.8 FLOW DISRUPTORS

[0441] In some examples of the technology, the flow of breathable gas delivered to the airways of the patient 1000 may be uncomfortable, for example due to the velocity, directionality, or laminar nature of the flow. This can be perceived as a cold spot, a blowing sensation, increased dryness at the point of impact with the face, and / or general annoyance or greater awareness of the flow. As many of the patient interfaces 3000 described herein are intended for use during sleep, these effects can have a negative effect on sleep quality.

[0442] For example, Fig. 8 shows a partial cross-sectional view of an oro-nasal or nasal cradle patient interface 3000 where the connection port 3600 is oriented in a substantially inferior-superior direction. While this configuration allows the patient interface 3000 to be relatively compact and stable on the face of the patient 1000, one side effect is that the flow of breathable gas received into the patient interface 3000 is directed in an upwardly, or superior direction towards the nares of the patient 1000, in a direction generally indicated by arrows ‘A’. This can result in an uncomfortable sensation as the airflow hits the nares of the patient 1000.

[0443] The patient interface 3000 includes a seal-forming structure 3100 as described herein, which is attached to a shell 8002, which in this example is configured to provide the connection port 3600.

[0444] In some examples the seal -forming structure 3100 is constructed from a material which is resiliently deformable, such that, in use it can conform to the geometry of the patient’s face to form an airtight seal therewith. In contrast, the shell 8002 is constructed from a material having a higher rigidity than the seal-forming structure 3100 such as a thermoplastic, such as a polycarbonate, polypropylene or acrylic material. Accordingly, the shell 8002 is configured to provide support to the seal-forming structure 3100 in use, such that the seal-forming structure and shell 8002 can co-operate to provide the plenum chamber 3200.

[0445] In some examples, such as illustrated in Fig. 8 the shell 8002 may be permanently attached to the seal -forming structure 3100, so as to provide a cushion module that can be replaced as required. For example the seal-forming structure 3100 may be overmoulded to, or otherwise attached to the shell 8002 using a fastener such as an adhesive, to thereby provide a cushion module which defines a plenum chamber 3200. In other examples the seal-forming structure 3100 may be configured toreleasably attached to the shell 8002, for example to allow the seal-forming structure 3100 to be removed and replaced as necessary.

[0446] For example, the seal-forming structure 3100 may be configured to stretch over, or otherwise engage with the shell 8002 to provide a substantially airtight seal therebetween. In some examples the seal forming structure 3100 may attached to the shell 8002 using a clip 8004. In other examples the clip 8004 may be configured to provide an flow disruptor 9008 as described herein.

[0447] In some examples the clip 8004 may be attached to the seal-forming structure, such as using an adhesive or overmoulding process, while in other examples the clip may be releasably attached to the seal-forming structure.

[0448] The clip 8004 is configured to provide a substantially air-tight seal between the seal -forming structure 3100 and the shell 8002, for example by engaging with the shell (such as with an interference fit) or compressing at least a portion of the sealforming structure 3100 into engagement with the shell 8002.

[0449] In Fig. 8, the shell 8002 includes a shelf 8006 which extends from the shell 8002 in a substantially posterior direction towards the seal forming structure 3100. This shelf 8006, provides a surface 8008 to which the seal-forming structure 3100 and / or clip 8004 attaches in use. Preferably the surface 8008 is provided around a full perimeter of the inlet 8010 through which the flow of breathable gas passes in use. In some examples of patient interface, the inlet 8010 may be equivalent to the plenum chamber inlet ports 3254 described herein, for example in Fig. 7A the patient interface may include a feature equivalent to the shelf 8006 to provide a sealing surface 8008 around one or both of the plenum chamber inlet ports 3254-1.

[0450] In some examples the clip 8004 may be constructed of a resiliently deformable material such as a silicone or polyurethane such that the engagement between the clip 8004 and the shell 8002 forms a substantially air-tight seal. In other examples the clip 8004 may be constructed of the same material as the shell 8002, such as a polycarbonate, polypropylene or acrylic, such that the shell 8002 and clip 8004 engage each other with an interference or snap-fit connection. In other examples the clip 8004 may be constructed from the same material as the seal-forming structure 3100 for example the clip may be formed from a silicone.

[0451] Figs. 9A to 9D show another example of a shell 8002 and associated clip 8004 of a patient interface 3000. In this example the shell 8002 includes connectors9002 for connecting to a positioning and stabilising structure 3300 in use. For example, the connectors 9002 may be configured to attach to a conduit connection structure 3500 or arm connection structure 3504 in use.

[0452] In this example, a clip 8004 is provided which is configured to engage with the surface 8008 of the shelf 8006 surrounding the inlet 8010. The clip 8004 forms a loop shape which has an internal surface 9004 which is complementary to, or otherwise configured to seal with the corresponding surface 8008 on the shelf 8006. The outer surface 9006 of the clip may be configured to attach to, or otherwise be permanently attached to the seal -forming structure 3100.

[0453] The clip 8004 includes a flow disruptor 9008 in the form of a protrusion which extends from one edge 9010 of the clip in a radially inward direction, i.e., towards a centre of the loop such that when it is positioned on the shelf 8006, the flow disruptor 9008 is aligned with the flow of breathable gases provided through the inlet 8010 / connection port 3600.

[0454] The flow disruptor 9008 therefore at least partially obscures the inlet 8010 to thereby obstruct, deflect or disperse the airflow provided through the connection port 3600. As a result, the flow disruptor 9008 diffuses the flow of breathable gas received by the patient’s airways, increasing comfort and potentially increasing compliance with respiratory pressure therapies. As such, in some examples the flow disruptor may be referred to as an air diffuser.

[0455] In some examples the flow disruptor 9008 may act to add turbulence to the flow of breathable gas to reduce potential jetting effects on the patient’s face and / or airways. For example, the flow disruptor 9008 may be configured to separate the flow of breathable gas into two or more streams, such as one provided on either side of the protrusion 9008. These streams may rejoin on the patient side of the protrusion, causing increased turbulence in the airflow, reducing jetting effects within the patient interface 3000.

[0456] In some examples the flow disruptor 9008 may be constructed of a resiliently deformable material such as an elastomeric material such as silicone or rubber. In this way the protrusion may act to dampen vibrations in the patient interface, caused by the flow of breathable gas.

[0457] In some examples the flow disruptor 9008 is shaped as a tongue, having a substantially curved shape, wherein the flow disruptor 9008 has a first width ‘Wl’where it connects to the clip 8004 and a second width ‘W2’ at a free hanging end of the flow disruptor 9008. For example the first width ‘Wl’ may be between 8 mm and 20 mm inclusive, while the second width ‘W2’ may be between 5 and 10 mm inclusive. The flow disruptor may also have a thickness of between 0.1 mm to 10 mm inclusive such as between 0.5 mm, and 5 mm inclusive.

[0458] In one example the present technology provides a patient interface 3000 which is configured to receive a flow of breathable gas for treatment of a respiratory disorder, the patient interface comprising a flow disruptor 9008 positioned in the path of the flow of breathable gas such that it disrupts, deflects or diffuses the flow of breathable gas. It can further be advantageous for the protrusion to be positioned such that it does not obstruct the one or more vents 3450 in the patient interface 3000 in other words, the patient interface 3000 may be structured or arranged such that the vents 3450 are substantially unobstructed from the airways of the patient. In other words, the protrusion 9008 is configured such that it is not positioned between the oral and / or nasal airways of the patient and the one or more vents 3450. This can advantageously help to ensure that that adequate CO2 is removed from the plenum chamber 3200 on each breath, and further help to reduce flow impedance for the patient’s expired breath.

[0459] Fig. 10A to 10G show another example of the technology, in which a flow disruptor 9008 is provided within a compact patient interface 3000 configured to deliver a flow of breathable gas to the nasal airways of the patient 1000 in use.

[0460] In this example, the flow disruptor 9008 comprises a plurality of apertures 10002 through which the flow of breathable gas passes in use. The apertures 10002 are configured to force separation of the flow of breathable gas received via the connection port 3600 into a plurality of airflow streams, thereby diffusing the airflow, and reducing the jetting effect on the face and / or airways of the patient 1000.

[0461] In the illustrated example, the flow disruptor 9008 comprises a body 10004 which is contoured to match or otherwise be complementary to the internal profile of plenum chamber 3200, for example by matching the internal profile of the sealforming structure 3100, and / or the shell 8002. For example, the body 10004 may comprise a central portion which is 10006 substantially concave relative to the patient 1000 and / or seal forming structure 3100 such that it reduces the likelihood of coming into contact with the face of the patient 1000, such as the nose of the patient.

[0462] In some examples the body 10004 of the flow disruptor 9008 may include a sidewall 10008 which is configured to extend in a posterior-anterior direction around a periphery of the flow disruptor 9008 to thereby provide separation between the apertures 10002 and any component which may restrict airflow through the apertures, such as the shell 8002 and / or the clip 8004. For example, the sidewall may extend between 1 mm and 6 mm inclusive in an posterior-anterior direction, such as approximately 3mm. For example, Fig. 10D shows a partial cross section of the flow disruptor 9008 in which the sidewall 10008 connects to an inwardly facing flange 10010 which extends in a radially inward direction so as to provide a contact surface which connects to the clip 8004. This however should not be seen as limiting, for example Fig. 10H shows another example of the technology in which the flange 10010 extends in a radially outward direction. This flange 10010 may in use facilitate connection to the shell 8002 or clip 8004 for example by an overmoulding process or by using a fastener such as an adhesive.

[0463] In some examples the wall thickness ‘W’ may be approximately 0.5 mm to 3mm inclusive, such as between 0.5mm and 1mm inclusive, this thickness can thereby allow for a compact flow disruptor, or be increased to provide additional durability as required. For example, any one or more of the front face 10012, sidewall 10008 and / or flange may have a wall thickness of between approximately 0.5 mm to 3 mm inclusive, such as between 0.5 mm and 1.5 mm inclusive.

[0464] Accordingly, the clip 8004 may be configured to attach both the seal forming structure 3100 and the flow disruptor 9008 to the shell 8002. In some applications it may be advantageous for the flow disruptor 9008 to be removably attached to the clip 8004, for example to allow for cleaning or replacement, while in other examples it may be advantageous for the flow disruptor 9008 to be permanently attached to the clip 8004 (such as by an overmoulding process as described herein) for example to prevent the flow disruptor 9008 from coming dislodged in use.

[0465] In some examples, it may be advantageous for the flow disruptor 9008 to be removably attached to the seal-forming structure 3100, for example to allow for cleaning or replacement, while in other examples it may be advantageous for the flow disruptor 9008 to be permanently attached to the seal-forming structure 8004 (such as by an overmoulding process or adhesive as described herein) for example to prevent the flow disruptor 9008 from coming dislodged in use.

[0466] In some examples of the technology, the flow disruptor 9008 may include a plurality of apertures 10002 wherein at least two of the plurality of apertures are of different sizes. For example, with reference to Figs. 10F and 10G, in some examples of the technology, the flow disruptor 9008 comprises a plurality of apertures 10002 wherein each of the apertures 10002 are substantially the same size. In these examples the plurality of apertures 10002, may be regularly spaced i.e., the flow disruptor 9008 may comprise an array of apertures 10002, such as between approximately 45 and 65 apertures such as approximately 55 apertures.

[0467] It may be advantageous for the total combined aperture 10002 area to be equal to or greater than the total area of the front face 10012 which does not have holes, or otherwise obstructs the airflow. For example, with reference to a patient interface without a flow disruptor 9008, the total cross-sectional area impacted by the flow disruptor 9008 is preferably between 10% and 50% inclusive. Put another way, the flow disruptor may be configured to have protrusions or a front face which obstructs between 10% and 50% of the total cross-sectional area of the plenum chamber, leaving 50% to 90% (inclusive) of the area open (for example using the one or more apertures 10002). This approach can advantageously result in desirable flow disruption / diffusion while minimising the effects on flow impedance.

[0468] In other examples, such as the embodiment shown in Fig. 10G, the flow disruptor 9008 may comprise a plurality of apertures 10002 wherein at least two of the plurality of apertures 10002 are of different sizes to each other. For example, the plurality of apertures 10002 may comprise a first set of apertures 10002A wherein each aperture of the first set of apertures has a first aperture size, and a second set of apertures 10002B, wherein each aperture of the second set of apertures having a second size, where the second size is greater than the first size. In some examples the flow disruptor may further comprise a third set of apertures 10002C (noting that the set may be a set of one aperture), wherein each aperture of the third set of apertures has a third size, and wherein the third size is greater than the first size and second size.

[0469] In some examples the apertures 10002 may be substantially circular, however this should not be seen as limiting and in other examples, the apertures 10002 may include any suitable shape, including for example slots.

[0470] For example, the first aperture size may have a cross-sectional area of between approximately 0.75 mm2, and approximately 7 mm2inclusive, such asapproximately 3 mm2, the second aperture size may have a cross-sectional area of between approximately 7 mm2, and 38 mm2inclusive, such as approximately 20 mm2, the third aperture size may have a cross-sectional area of between approximately 80 mm2 and approximately 315 mm2inclusive, such as approximately 175 mm2.

[0471] In some examples it may be beneficial for the apertures 10002 near to the centre of the flow disruptor 9008 to have a smaller aperture size and the apertures nearer to the lateral sides of the flow disruptor 9008 to have greater aperture sizes. This arrangement may advantageously encourage a reduced airflow in the regions adjacent to the patient nose, in use, and increased airflow around the sides of the patient’s 1000 nose. This can advantageously reduce the effect of jetting on the patient’s 1000 face / nose in use.

[0472] The size of the apertures 10002 can be an important design consideration as reducing the apertures 10002 forces the flow of breathable gas through a smaller area, resulting in a faster flow velocity to maintain the same flow rate / volume.However, a small hole size can also increase the impedance / pressure drop caused by the flow disruptor 9008. Therefore, it can be beneficial that the total surface area covered by the front face 10012 of the flow disruptor 9008 is less than 50% of the available surface area between opposing walls of the plenum chamber 3200. In other words, it can be beneficial for the combined surface area of the apertures 10002 to be greater than or equal to the combined surface area of the front face 10012 of the flow disruptor 9008, such as between 50% and 90% of the total available surface area, inclusive.

[0473] In order to maximise the total surface area of the apertures 10002 while limiting the jetting effects on the patient’s face, it can be beneficial to provide a greater flow around the sides of the flow disruptor 9008 for example either by positioning the diffuser over only a central portion of the inlet 8008 as shown in Fig. 9A to 9D, or by having larger apertures 10002 positioned furthest from the central axis ‘C’ i.e., distal to the central axis ‘C’ as shown in Fig. 10G.

[0474] The inventors have found that the use of a flow disruptor 9008 such as those described in relation to Figs. 10F and 10G can result in a reduction of the maximum velocity at the nose of the patient of approximately 40% while having a reduction in pressure drop of around 2%.

[0475] It should be appreciated that in the foregoing example the flow disruptor 9008 is described in relation to a nasal patient interface 3000 (i.e., a patient interface 3000 configured to deliver a flow of breathable gas to the nasal airways of the patient 1000), the present technology may equally be applied to full-face and oro-nasal patient interfaces 3000 (i.e., patient interfaces that are configured to deliver a flow of breathable gas to the oral and nasal airways of the patient).

[0476] In a yet further example of the technology shown in Fig. 11 A and 1 IB a flow disruptor 9008 may be provided in the shell 8002, for example the flow disruptor 9008 may be formed as a protrusion which is positioned in the path of the incoming flow of breathable gas from the connection port 3600.

[0477] In these examples the flow disruptor 9008 may be moulded as part of the shell 8002 or otherwise attached to the shell 8002, for example using a fastener or adhesive. In other examples the flow disruptor 9008 may be provided by the sealforming structure 3100, for example as protrusion which extends at least partially across the inlet 8010.

[0478] The flow disruptor 9008 is preferably positioned such that the flow of breathable gas exiting the connection port 3600, at least partially collides with, and is therefore partially diverted and diffused by the flow disruptor 9008. For example, the flow disruptor may be formed as part of, or otherwise attached to the connection port 3600, such that the flow of air exiting the connection port. In the illustrated example the flow disruptor 9008 is configured to extend between the connection port 3600 and the shelf 8006, such that it at least partially divides the inlet 8010 through which the flow of breathable gas passes in use. Accordingly, by dividing the inlet 8010 the incoming flow of breathable gas is forced to divide into two flow streams (generally indicated by arrows ‘Al’ and ‘A2’) thereby diffusing the flow of breathable gas. These two flow streams may rejoin after passing the flow disruptor 9008, this has been found to add turbulence to the airflow, further aiding in reducing the unpleasant jetting effect.

[0479] In some examples the flow disruptor 9008 may induce vortices in the flow of breathable gas, thereby further reducing the perceived jetting effect on the patient’s face.

[0480] While in the present example the flow disruptor 9008 extends in a substantially inferior-superior direction, to thereby laterally divide the flow of breathable gas, this should not be seen as limiting and in other examples of thetechnology, such as where conduit headgear is used, the flow disruptor 9008 may extend in a substantially lateral, substantially lateral to contra-lateral direction and / or substantially in a transverse plane to divide the flow of breathable gas into inferior and superior portions. In yet further examples the flow disruptor 9008 may take any suitable shape or structure which is configured to divide the flow of breathable gas received from the connection port 3600 into two or more streams to thereby diffuse the flow of breathable gas.

[0481] An example of a flow disruptor 9008 according to the present technology and optimised for noise performance is shown in Figs. 12A and 12B in which the shell 8002 forms at least part of the plenum chamber 3200 of an ora-nasal or nasal cradle patient interface. For sake of clarity, the connection port which would be mounted to the anterior side of the shell 8002 is not shown, such that the interior of the plenum chamber 3200 is visible. In use, the seal-forming structure (not shown) would be provided to and be supported by the posterior side of the shell 8002. This may be achieved in a permanent fashion, by over-moulding or with suitable fasteners to form a cushion module, or in a removable fashion, through the use of snap-lock features or clips.

[0482] In this example, the flow disruptor 9008 may be formed as a vertically orientated bar-or pillar-like structure which is positioned in the plenum chamber 3200 such that it is in the path of the incoming flow of breathable gas from the connection port (not shown). As such, the flow disruptor 9008 separates the flow of air entering the plenum chamber 3200 into substantially two distinct streams.

[0483] The bar, shown here spanning the internal portion of the frame 8002 between its respective inferior and superior surfaces (not visible), is configured with a substantially V-shaped profile; i.e. two arms or wings 9008a, 9008b connected at their respective ends by a linking portion 9008c. As best seen in Fig. 12 B, the linking portion 9008c forms the leading edge LE of the flow disruptor; as the flow of air entering the plenum chamber 3200, it contacts the leading edge of the flow disruptor and is divided into two streams, each substantially flowing along arms 9008a, 9008b respectively. The bar is arranged such that the arms 9008a, 9008b diverge or taper away from the linking portion 9008c at an angle towards a trailing edge TE. This divergence is towards the posterior side of the plenum chamber, i.e. the side closest to the seal-forming structure that contacts the patient face in use. The angle between therespective arms 9008a, 9008b is shown here as approximating 70°. In some instances, this angle may be greater, for example 90° or more. It will be appreciated that the greater the angle between the respective arms 9008a, 9008b, the greater the divergence of the resulting streams of air, such that they may be directed more into the lateral portions of the plenum chamber 3200.

[0484] In one form, the flow disruptor 9008 may be integrally formed with the shell 8002. As such it may be formed from a suitably rigid thermoplastic, such as a polycarbonate, polypropylene or acrylic material.

[0485] In some other forms, the flow disruptor 9008 may be a separate structure that is releasably attached to the shell 8002. This may be advantageous in that it may allow the user to adapt the degree of divergence of the flow of air entering the plenum chamber 3200 to their preferences by replacing the flow disruptor 9008. For example, the inferior and superior ends (not visible) of the flow disruptor may be snap-locked into complementary structures (not visible) provided to the respective inferior and superior surfaces of the internal portion of the shell 8002. The user would initially present the flow disruptor 9008 to the plenum chamber 3200 in substantially horizontal orientation, before rotating it into a vertical orientation where the respective inferior and superior ends engage with the corresponding surfaces of the internal portion of the shell 8002.

[0486] In further forms not shown here, the flow disruptor 9008 may be integral to a clip or intermediary member positioned between the shell 8002 and the connection port (not shown) in use. For example, the flow disruptor may be provided as part of a structure that clips into the anterior side of the shell, with the connection port in turn engaging or otherwise connecting to said structure, either permanently or in a releasable arrangement. In some examples, the flow disruptor may be provided as part of a structure that clips into the posterior side of the shell, with the seal-forming structure in turn engaging or otherwise connecting to said structure, either permanently or in a releasable arrangement.

[0487] In forms where the flow disruptor 9008 is separate to the shell 8002, it may be formed from a material different to that used for the shell 8002. This may allow the flow disruptor to be configured to enhance and supplement its functionality; for example, the use of a slightly porous material to further retard the flow of air passing over the surfaces of the flow disruptor. Alternatively, it may be formed from the samematerials used for the shell, i.e. a suitably rigid thermoplastic, such as a polycarbonate, polypropylene or acrylic material. As noted previously, having the flow disruptor as a separate structure to the shell may be useful in conferring the user of the patient interface with ability to switch out the flow disruptor, depending on their preferences. It may also better facilitate cleaning or maintenance of the patient interface.

[0488] As can be seen, the flow disruptor 9008 faces the flow of air entering the plenum chamber from the air circuit (not shown) that engages with the connection port (not shown). In use, this prevents the flow of air from directly hitting or otherwise contacting the nares of the patient wearing the nasal mask. Instead, the arms 9008a, 9008b of the flow disruptor 9008 divides the incoming airflow into two streams, left and right, diffusing and retarding the flow of air entering the plenum chamber 3200 via the connection port (not shown). As it passes over the respective arms 9008a, 9008b, drag is induced which causes retardation of the flow of air. Furthermore, as the stream of air passes over the trailing edge TE of each arm 9008a, 9008, a vortex is formed. This also acts to slow down the flow of air prior to contact with and entry to the nares of the patient (not shown) This may be a more comfortable sensation for the patient. Furthermore, the reduction in kinetic energy, due to the slower flow of air at the trailing edge TE of the respective arms 9008a, 9008b, may also bring accompanying noise reduction; this may be useful for patient comfort and compliance when wearing the patient interface to which the shell 8002 is provided.

[0489] If desired, the cross-sectional profile of the flow disruptor 9008 may be configured to further push airflow entering the plenum chamber 3200 via the connection port (not shown) into the lateral portions of the plenum chamber 3200. This may be achieved, for example, by increasing the angle between the respective arms 9008a, 9008b of the V-shaped profile of the flow disruptor 9008.

[0490] Fig. 12C shows a simulation of the velocity of the flow of air through a patient interface 3000, with the flow disruptor 9008 as described in Figs. 12A and 12B, arranged or otherwise positioned at about the plane of the mid-height of the nares of the patient. The darker the air flow, the greater its velocity. As can be seen, the velocity of the airflow AF is greatest at the point of entry to the plenum chamber 3200. The airflow then hits the flow disruptor 9008 that is provided proximate the anterior side of the plenum chamber 3200, creating a left stream L and a right stream R of air deeper into the plenum chamber. At the posterior side of the plenum chamber, proximate theseal-forming structure that bears against the patient’s face in use, the air flow velocity of the respective left stream L and right stream R is retarded compared to the anterior side. As already noted, this has the effect of diffusing the air flow and reducing noise.

[0491] Although the flow disruptor 9008 of Figs. 12A and 12B is shown as being orientated substantially vertically, i.e. spanning the height dimension of the plenum chamber 3200, in other examples not shown here, it may alternatively span the width dimension of the plenum chamber. As such, rather than splitting the airflow into a left stream and a right stream, a flow disruptor so orientated would split the airflow into an anterior or upper stream and an inferior or lower stream.

[0492] Another configuration of the flow disrupter 9008, for use with the shell 8002 of an ora-nasal or nasal patient interface, is shown in Figs. 13 A and 13B. In this configuration, the flow disruptor has a first arm, 9008a and a second arm 9008b with a channel 9008d therebetween them. As such, the linking portion of the flow disruptor shown in Figs. 12A and 12B is absent, at least along a substantial portion of the height of the flow disruptor. This means that the flow of air entering the plenum chamber 3200 is divided substantially into three streams of air; one flowing along the first arm 9008a, one flowing along the second arm 9008, and one flowing through the channel 9008d.

[0493] The arms 9008a, 9008b diverge or taper outwards from their respective leading edge LE (the edge proximate the anterior side of the plenum chamber 3200) to their respective trailing edge TE (proximate the posterior side of the plenum chamber 3200). As a consequence, the channel 9008d has a narrow opening which is defined by the leading edge LE of the respective arms 9008a, 9008b but a wider exit defined by the trailing edge TE of the respective arms 9008a, 9008b. This configuration may help with reducing the velocity of the stream of air flowing through the channel 9008d, and therefore reduces the volume of the noise of the air as it flows through the flow disruptor 9008.

[0494] It will be noted that the trailing edge TE of the arms 9008a, 9008b are serrated or otherwise contoured. This configuration helps reduce the velocity of the air flow at this region of the flow disruptor 9008; as such there may be a reduction in the noise of the air as it passes over the trailing edge TE.

[0495] In some examples, the arms 9008a, 9008b may be linked at their respective superior and inferior ends by a linking member (not visible) to form a unitary structure.This linking member may serve as a means by which the flow disruptor may be mounted to the frame 8002. However, in some instances, the flow disruptor 9008 may be integrally formed with the shell 8002 or alternatively provided as part of a clip or intermediary member that engages or otherwise connects to the anterior or posterior side of the plenum chamber 3200 as previously described in respect of Figs. 12A and 12B.

[0496] As best understood from Fig. 13C, showing a simulation of the airflow AF through the patient interface 3000 to which the flow disruptor 9008 as described in Figs. 13 A and 13B is provided, in this configuration a portion of the airflow AF entering the plenum chamber 3200, may be substantially diverted into three streams; a left stream L, a right stream R, and a central stream C flowing through the channel 9008d of the flow disruptor. As a consequence of this, the velocity of the flow of air is reduced at the sealing forming structure proximate the patient’s nose, which may contribute to user comfort when wearing the patient interface.

[0497] Yet another example of a flow disruptor 9008 is shown in Fig. 14A, integrated into a shell 8002 which forms at least part of the plenum chamber of an ora- nasal or nasal cradle patient interface. As in the previous examples described, the shell 8002 and flow disruptor 9008 may be formed from a suitably rigid material such as thermoplastic of polycarbonate, polypropylene or acrylic material. In this example, the shell 8002 forms a portion of the anterior side of the plenum chamber (not shown and is configured to include the connection port 3600. The connection port 3600 is arranged as a cylindrical body or protrusion formed by a wall extending from the circumference of the connection port. In use, the connection port 3600 receives the downstream end of the air circuit (not shown); this may be inserted into, or over, the connection port, depending on the respective configuration of the connection port and air circuit.

[0498] The flow disruptor 9008 is provided to and arises from the internal circumference of the connection port 3600, such that it extends into the path of the air flowing there through. In this example, the flow disruptor 9008 is configured as a pair of opposing arms or wing-like structures 9012a and 9012b, which shall now be referred to as wings, extending radially from the wall of the connection port 3600 substantially in a horizontal plane. In use, these wings 9012a, 9012b disrupt the flow of air entering the patient interface. The flow of air is split substantially into threestreams. A first stream flowing over the respective wings and the second stream flowing under the respective wings, thereby inducing drag and therefore a reduction in the velocity of the flow of air. A third stream flows into the region between the respective wings 9012a, 9012b. For the patient, the impact of the flow of air on the nares may be reduced, potentially resulting in greater comfort. In Fig. 14 A, the respective wings 9012a, 9012b are arranged to substantially extend from the midpoint of the wall of the connection port 3600. In some examples, not shown here, the respective wings may extend, still in a horizontal plane, but from a point on the circumference of the connection port that is superior (or inferior) to the midpoint of same. As such the wings 9012a, 9012b may favour the superior (or inferior) portion of the connection port 3600.

[0499] In some examples of the technology, the flow disruptor 9008 may comprise three or more wings provided to the connection port. Such examples are shown in Figs. 14B and 14C respectively. The configuration depicted in Fig. 14B shows a configuration in which three wing 9012a, 9012b, 9012c are provided to the shell 8002 spaced equidistance apart around the inner circumference of the connection port 3600. Each wing 9012a, 9012b, 9012c is orientated such that it extends radially towards the centre of the connection port. The example of Fig. 14C is a configuration with four wings 9012a, 9012b, 9012c, 9012d arranged equidistance around the inner circumference of the connection port 3600, each orientated such that they extend radially to the centre of the connection port. While the wings 9012a to 9012d shown in Fig. 14C are shown as being arranged in pairs along vertical and horizontal axes respectively, in other forms, they may be arranged in pairs along respective diagonal axes.

[0500] In Figs. 14D and 14E, an example of a shell 8002 is illustrated in which the flow disruptor 9008 provided to the connection port 3600 comprises a pair of wings 9012a and 9012b wherein each wing is provided with a winglet 9014a and 9014b. As such each wing will be understood to have a first portion (corresponding to the wings 9012a, 9012b and a second portion (corresponding to the winglets 9014a, 9014b). In the illustrated example, each winglet is angled at 30° incline from the horizontal, in a superior orientation. However, this is not meant to be limiting, and the angle may be more or less, depending on the desired performance characteristics. Furthermore it willalso be understood that in some examples, not shown here, the angle may be such that the winglet is declined, towards a posterior orientation.

[0501] As shown, the configuration of the flow disruptor 9008 means that the leading edge LE and trailing edge TE has two distinct portions, each corresponding to the wing 9012a and its winglet 9014b. This configuration may reduce the size of the vortices that may form at the trailing edge and tip of the wing. Concurrently with the reduction in the size of the vortices, there may be a reduction in the kinetic energy and noise of the flow of air. This may enhance patient comfort as the air contacts and enters the nares. In the illustrated example of Figs. 14D and 14E, the leading edge LE and trailing edge TE are of substantially the same thickness. However, in some examples not shown here, the trailing edge may be reduced in thickness relative to the leading edge LE. Furthermore, the trailing edge may be contoured or serrated, as discussed above in respect of the example of the flow disruptor shown in Figs.13 A and 13B.This may be of assistance in reducing noise downstream of the disruptor as the respective streams of air formed by passing over and under the wing and winglet meet.

[0502] Variations of the flow disruptor 9008 shown in Fig. 14D may be readily envisaged given the preceding disclosure. For instance, in some forms not shown here, the horizontal plane from which the wing extends from the inner wall of the connection port may be orientated to favour the superior portion of the connection port (or the inferior portion). In other forms not shown here, the flow disruptor 9008 may comprise three (or more) wings arranged equidistance apart around the inner circumference of the connection port 3600 (similar to what is shown in Figs. 14B and 14C), with each wing having its own winglet. In yet further forms not shown here, each wing may be provided with two (or more) winglets, i.e. comprised of three or more portions, each successive winglet being at an increased angle from the horizontal; in a non-limiting example, a first winglet extending from the wing may be at 30° from the horizontal, with a second winglet extending from the first winglet at 45° from the horizontal.

[0503] Referring to Fig. 14F, this depicts a flow disruptor 9008 with a relatively thick wing 9012a, 9012b and winglet combination 9014a, 9014b, compared to the relatively low-profile configuration of Fig. 14D. The extra thickness of the wing 9012a, 9012b and winglet 9014a, 9014b means the leading edge presents a greater frontal surface area to the flow of air entering the connection port and may result ingreater divergence of the respective upper and lower streams of air passing over the flow disruptor.

[0504] An alternative flow disruptor 9008 configuration is shown in Fig. 15 A, integrated into a shell 8002 which forms at least part of the plenum chamber of an ora- nasal or nasal cradle patient interface. As with the example of Fig. 14A, the shell is configured to provide the connection port 3600 for the air circuit (not shown).

[0505] In this form, each wing 9012a, 9012b is provided with two winglets: first winglets 9014a, 9014b and second winglets 9016a, 9016b. The first winglets 9014a, 9014b extend away from their respective wings 9012a, 9012b in a substantially superior orientation; in the illustrated example, at about 75 to 80° from the horizontal. The respective second winglets 9016a, 9016b extend away from their respective wings 9012a, 9012b in a substantially inferior orientation; in the illustrated example, at about 45 to 60° from the horizontal. A flow disruptor 9008 with this configuration substantially quarters the flow of air passing through the connection port 3600, although a portion of the air still flows through the central portion of the connection port.

[0506] As will be best understood from Fig. 15B, the respective first winglet 9014b and second winglet 9016b are associated with one of the leading edge LE and trailing edge TE of the wing 9012b which arises from the inner circumference 3602 of the connection port 3600 of the shell 8002. The leading edge of the wing 9012b of the flow disruptor 9008 is substantially continuous with the leading edge LE of the second winglet 9016b, while the trailing edge is of the wing 9012b is substantially continuous with the first winglet 9014b (it will be appreciated that this arrangement could be reversed if desired). Furthermore, the relative depth (from the anterior to the posterior) of the winglets 9014b, 9016b also differ. The second winglet 9016b is of a reduced depth relative to the first wing winglet 9014b. This may be useful in reducing or eliminating vortices from forming in the flow of air, which in turn may affect drag and / or noise performance.

[0507] In some examples not shown here, the leading edge LE and trailing edge TE of the wing and / or winglet may be optimised for desired performance. In one such instance, one or both of the wing and winglet may be configured such that their cross- sectional profile tapers, i.e. narrows, from the leading edge to the trailing edge. Such tapering may be of assistance in improving drag and / or noise performance. Similarly,the trailing edge may be contoured or serrated as discussed above with respect to certain other examples of the flow disruptor.

[0508] While shown in Fig. 15B as being of different lengths (as can be seen, the first winglet 9014b has a greater length than the second winglet 9016b), in some other examples, the winglets 9014b, 9016b may be different lengths and angles (relative to the wing 9012b) depending on the desired performance characteristics; these may be greater or lesser diffusion of the flow of air, noise performance and so on. Furthermore, in some instances, the orientation of the winglets provided to the respective leading edge LE and trailing edge TE may vary. For example, the winglet forming at least part of the leading edge of the flow disruptor may extend in a superior orientation while that forming at least part of the trailing edge may extend in an inferior orientation.5.8.1 Heat Moisture Exchangers

[0509] Another type of device which may be positioned within a plenum chamber 3200 of a patient interface is a heat moisture exchanger. In some applications these devices may act as flow disruptors, however these devices have a number of key differences from the flow disruptors 9008 of the present technology including that: the flow disruptors 9008 of the present technology do not need to constructed of a hygroscopic material. For example, the flow disruptor may be constructed of a silicone, textile or polycarbonate material. These are materials which are already used within patient interfaces, and therefore the flow disruptors of the present invention may be more cost effective to manufacture.

[0510] Heat moisture exchangers also generally need to have much smaller apertures 10002 to aid in trapping and retaining moisture within the patient interface 3000. For example in some examples the apertures may have a cross-sectional area of 0.3mm2or smaller this can add to the manufacturing cost (as moulding or forming small holes can require complex tooling), increase the flow impedance within the interface (reducing the therapeutic efficacy of the PAP treatment, and increasing breathing discomfort which can reduce compliance), and result in reduced CO2 washout from the plenum chamber 3200 which can be potentially hazardous to the patient.

[0511] In addition, the materials used in heat moisture exchangers are generally expensive, can be difficult to clean, and need to be handled carefully to preventcontamination. For example, the materials used in the wet airflow pathway need to meet strict biocompatibility requirements, including ensuring that they do not degrade over time.

[0512] Heat moisture exchangers also generally have a greater thickness, to aid in trapping the moisture exhaled by the patient, as such they can be difficult to position within the patient interface 3000 without coming into contact with the face of the patient, such as the patient’s nose. For example, a heat moisture exchanger may have a thickness of between 5mm and 10mm, wherein the flow disruptors of the present technology, may have a wall thickness ‘W’ of approximately l-3mm, as described herein allowing a more compact patient interface.5.9 GLOSSARY

[0513] For the purposes of the present technology disclosure, in certain forms of the present technology, one or more of the following definitions may apply. In other forms of the present technology, alternative definitions may apply.5.9.1 General

[0514] 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.

[0515] 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.

[0516] 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.

[0517] In another example, ambient pressure may be the pressure immediately surrounding or external to the body.

[0518] 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.

[0519] Automatic Positive Airway Pressure (APAP) therapy: CPAP therapy in which the treatment pressure is automatically adjustable, e.g. from breath to breath,between minimum and maximum limits, depending on the presence or absence of indications of SDB events.

[0520] Continuous Positive Airway Pressure (CPAP) therapy: Respiratory pressure therapy in which the treatment pressure is approximately constant through a respiratory cycle of a patient. In some forms, the pressure at the entrance to the airways will be slightly higher during exhalation, and slightly lower during inhalation. In some forms, the pressure will vary between different respiratory cycles of the patient, for example, being increased in response to detection of indications of partial upper airway obstruction, and decreased in the absence of indications of partial upper airway obstruction.

[0521] 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’.

[0522] In the example of patient respiration, a flow rate may be nominally positive for the inspiratory portion of a breathing cycle of a patient, and hence negative for the expiratory portion of the breathing cycle of a patient. Device flow rate, Qd, is the flow rate of air leaving the RPT device. Total flow rate, Qt, is the flow rate of air and any supplementary gas reaching the patient interface via the air circuit. Vent flow rate, Qv, is the flow rate of air leaving a vent to allow washout of exhaled gases. Leak flow rate, QI, is the flow rate of leak from a patient interface system or elsewhere. Respiratory flow rate, Qr, is the flow rate of air that is received into the patient's respiratory system.

[0523] 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.

[0524] 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.

[0525] 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.

[0526] 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.

[0527] 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.

[0528] 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.

[0529] 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”.

[0530] Medical Oxygen: Medical oxygen is defined as oxygen enriched air with an oxygen concentration of 80% or greater.

[0531] Patient: A person, whether or not they are suffering from a respiratory condition.

[0532] Pressure: Force per unit area. Pressure may be expressed in a range of units, including cmH20, g-f / cm2 and hectopascal. 1 cmH20 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 cmH20.

[0533] 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.

[0534] 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.

[0535] Ventilator: A mechanical device that provides pressure support to a patient to perform some or all of the work of breathing.5.9.1.1 Materials & their properties

[0536] Hardness: Refers to durometer or indentation hardness, which is a material property measured by indentation of an indentor (e.g., as measured in accordance with ASTM D2240).• ‘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, and may not e.g. readily deform under finger pressure.

[0537] Silicone or Silicone Elastomer: A synthetic rubber. In this specification, a reference to silicone is a reference to liquid silicone rubber (LSR) or a compression moulded silicone rubber (CMSR). One form of commercially available LSR is SILASTIC (included in the range of products sold under this trademark), manufactured by Dow Corning. Another manufacturer of LSR is Wacker. Unless otherwise specified to the contrary, an exemplary form of LSR has a Shore A (or Type A) indentation hardness in the range of about 35 to about 45 as measured using ASTM D2240.

[0538] Polycarbonate: a thermoplastic polymer of Bisphenol-A Carbonate.5.9.1.2 Mechanics

[0539] Axes: a. Neutral axis: An axis in the cross-section of a beam or plate along which there are no longitudinal stresses or strains. b. Longitudinal axis: An axis extending along the length of a shape. The axis generally passes through a center of the shape. c. Circumferential axis: An axis oriented perpendicularly with respect to the longitudinal axis. The axis may be specifically present in pipes, tubes, cylinders, or similar shapes with a circular and / or elliptical cross section.

[0540] Deformation: The process where the original geometry of a member changes when subjected to forces, e.g. a force in a direction with respect to an axis. The process may include stretching or compressing, bending and, twisting.

[0541] Elasticity: The ability of a material to return to its original geometry after deformation.

[0542] 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.

[0543] Resilience: Ability of a material to absorb energy when deformed elastically and to release the energy upon unloading.

[0544] Resilient: Will release substantially all of the energy when unloaded. Includes e.g. certain silicones, and thermoplastic elastomers.

[0545] 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.

[0546] 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.

[0547] 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.

[0548] Viscous: The ability of a material to resist flow.

[0549] Visco-elasticity: The ability of a material to display both elastic and viscous behaviour in deformation.

[0550] Yield: The situation when a material can no longer return back to its original geometry after deformation.5.9.1.3 Structural Elements

[0551] Compression member: A structural element that resists compression forces.

[0552] 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.

[0553] 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.

[0554] 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.

[0555] Tie (noun): A structure designed to resist tension.

[0556] Thin structures: a. Beams, i. A beam may be relatively long in one dimension compared to the other two dimensions such that the smaller dimensions are comparatively thin compared to the long dimension b. Membranes, i. Relatively long in two dimensions, with one thin dimension. Readily deforms in response to bending forces. Resists being stretched, (might also resist compression). c. Plates & Shells i. These may be relatively long in two directions, with one thin dimension. They may have bending, tensile, and / or compressive stiffness.

[0557] Thick structures: Solids

[0558] 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 / orarranged to ‘seal’ or to effect ‘sealing’ therebetween without requiring a separate ‘seal’ element per se.

[0559] 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.

[0560] 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.

[0561] 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.

[0562] 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.5.9.2 Respiratory cycle

[0563] Apnea: According to some definitions, an apnea is said to have occurred when flow falls below a predetermined threshold for a duration, e.g. 10 seconds. An obstructive apnea will be said to have occurred when, despite patient effort, some obstruction of the airway does not allow air to flow. A central apnea will be said to have occurred when an apnea is detected that is due to a reduction in breathing effort, or the absence of breathing effort, despite the airway being patent. A mixed apnea occurs when a reduction or absence of breathing effort coincides with an obstructed airway.

[0564] Breathing rate: The rate of spontaneous respiration of a patient, usually measured in breaths per minute.

[0565] Duty cycle: The ratio of inhalation time, Ti to total breath time, Ttot.

[0566] Effort (breathing): The work done by a spontaneously breathing person attempting to breathe.

[0567] Expiratory portion of a breathing cycle: The period from the start of expiratory flow to the start of inspiratory flow.

[0568] Flow limitation: Flow limitation will be taken to be the state of affairs in a patient's respiration where an increase in effort by the patient does not give rise to a corresponding increase in flow. Where flow limitation occurs during an inspiratory portion of the breathing cycle it may be described as inspiratory flow limitation. Where flow limitation occurs during an expiratory portion of the breathing cycle it may be described as expiratory flow limitation.

[0569] Types of flow limited inspiratory waveforms:(i) Flattened: Having a rise followed by a relatively flat portion, followed by a fall.(ii) M-shaped: Having two local peaks, one at the leading edge, and one at the trailing edge, and a relatively flat portion between the two peaks.(iii) Chair-shaped: Having a single local peak, the peak being at the leading edge, followed by a relatively flat portion.(iv) Reverse-chair shaped: Having a relatively flat portion followed by single local peak, the peak being at the trailing edge.

[0570] Hypopnea: According to some definitions, a hypopnea is taken to be a reduction in flow, but not a cessation of flow. In one form, a hypopnea may be said to have occurred when there is a reduction in flow below a threshold rate for a duration. A central hypopnea will be said to have occurred when a hypopnea is detected that is due to a reduction in breathing effort. In one form in adults, either of the following may be regarded as being hypopneas:(i) a 30% reduction in patient breathing for at least 10 seconds plus an associated 4% desaturation; or(ii) a reduction in patient breathing (but less than 50%) for at least 10 seconds, with an associated desaturation of at least 3% or an arousal.

[0571] Hyperpnea: An increase in flow to a level higher than normal.

[0572] Inspiratory portion of a breathing cycle: The period from the start of inspiratory flow to the start of expiratory flow will be taken to be the inspiratory portion of a breathing cycle.

[0573] Patency (airway): The degree of the airway being open, or the extent to which the airway is open. A patent airway is open. Airway patency may be quantified,for example with a value of one (1) being patent, and a value of zero (0), being closed (obstructed).

[0574] Positive End-Expiratory Pressure (PEEP): The pressure above atmosphere in the lungs that exists at the end of expiration.

[0575] Peak flow rate (Qpeak): The maximum value of flow rate during the inspiratory portion of the respiratory flow waveform.

[0576] Respiratory flow rate, patient airflow rate, respiratory airflow rate (Qr): These terms may be understood to refer to the RPT device’s estimate of respiratory flow rate, as opposed to “true respiratory flow rate” or “true respiratory flow rate”, which is the actual respiratory flow rate experienced by the patient, usually expressed in litres per minute.

[0577] Tidal volume (Vt): The volume of air inhaled or exhaled during normal breathing, when extra effort is not applied. In principle the inspiratory volume Vi (the volume of air inhaled) is equal to the expiratory volume Ve (the volume of air exhaled), and therefore a single tidal volume Vt may be defined as equal to either quantity. In practice the tidal volume Vt is estimated as some combination, e.g. the mean, of the inspiratory volume Vi and the expiratory volume Ve.

[0578] Inhalation Time (Ti): The duration of the inspiratory portion of the respiratory flow rate waveform.

[0579] Exhalation Time (Te): The duration of the expiratory portion of the respiratory flow rate waveform.

[0580] Total Time (Ttot): The total duration between the start of one inspiratory portion of a respiratory flow rate waveform and the start of the following inspiratory portion of the respiratory flow rate waveform.

[0581] Typical recent ventilation: The value of ventilation around which recent values of ventilation Vent over some predetermined timescale tend to cluster, that is, a measure of the central tendency of the recent values of ventilation.

[0582] Upper airway obstruction (UAO): includes both partial and total upper airway obstruction. This may be associated with a state of flow limitation, in which the flow rate increases only slightly or may even decrease as the pressure difference across the upper airway increases (Starling resistor behaviour).

[0583] Ventilation (Vent): A measure of a rate of gas being exchanged by the patient’s respiratory system. Measures of ventilation may include one or both ofinspiratory and expiratory flow, per unit time. When expressed as a volume per minute, this quantity is often referred to as “minute ventilation”. Minute ventilation is sometimes given simply as a volume, understood to be the volume per minute.5.9.3 Ventilation

[0584] Adaptive Servo-Ventilator (ASV): A servo-ventilator that has a changeable, rather than fixed target ventilation. The changeable target ventilation may be learned from some characteristic of the patient, for example, a respiratory characteristic of the patient.

[0585] Backup rate: A parameter of a ventilator that establishes the minimum breathing rate (typically in number of breaths per minute) that the ventilator will deliver to the patient, if not triggered by spontaneous respiratory effort.

[0586] Cycled: The termination of a ventilator's inspiratory phase. When a ventilator delivers a breath to a spontaneously breathing patient, at the end of the inspiratory portion of the breathing cycle, the ventilator is said to be cycled to stop delivering the breath.

[0587] Expiratory positive airway pressure (EPAP): a base pressure, to which a pressure varying within the breath is added to produce the desired interface pressure which the ventilator will attempt to achieve at a given time.

[0588] End expiratory pressure (EEP): Desired interface pressure which the ventilator will attempt to achieve at the end of the expiratory portion of the breath. If the pressure waveform template □(□) is zero-valued at the end of expiration, i.e. □(□) = 0 when > = 1, the EEP is equal to the EPAP.

[0589] Inspiratory positive airway pressure (IPAP): Maximum desired interface pressure which the ventilator will attempt to achieve during the inspiratory portion of the breath.

[0590] Pressure support: A number that is indicative of the increase in pressure during ventilator inspiration over that during ventilator expiration, and generally means the difference in pressure between the maximum value during inspiration and the base pressure (e.g., PS = IPAP - EPAP). In some contexts, pressure support means the difference which the ventilator aims to achieve, rather than what it actually achieves.

[0591] Servo-ventilator: A ventilator that measures patient ventilation, has a target ventilation, and which adjusts the level of pressure support to bring the patient ventilation towards the target ventilation.

[0592] Spontaneous / Timed (S / T): A mode of a ventilator or other device that attempts to detect the initiation of a breath of a spontaneously breathing patient. If however, the device is unable to detect a breath within a predetermined period of time, the device will automatically initiate delivery of the breath.

[0593] Swing: Equivalent term to pressure support.

[0594] Triggered: When a ventilator, or other respiratory therapy device such as an RPT device or portable oxygen concentrator, delivers a volume of breathable gas to a spontaneously breathing patient, it is said to be triggered to do so. Triggering usually takes place at or near the initiation of the respiratory portion of the breathing cycle by the patient's efforts.5.9.4 Anatomy5.9.4.1 Anatomy of the face

[0595] Ala: the external outer wall or "wing" of each nostril (plural: alar)

[0596] Alar angle: An angle formed between the ala of each nostril.

[0597] Alare: The most lateral point on the nasal ala.

[0598] 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.

[0599] Auricle: The whole external visible part of the ear.

[0600] (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.

[0601] (nose) Cartilaginous framework: The cartilaginous framework of the nose comprises the septal, lateral, major and minor cartilages.

[0602] Columella: the strip of skin that separates the nares and which runs from the pronasale to the upper lip.

[0603] 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.

[0604] 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.

[0605] Glabella: Located on the soft tissue, the most prominent point in the midsagittal plane of the forehead.

[0606] 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.

[0607] Lip, lower (labrale inferius): The lip extending between the subnasale and the mouth.

[0608] Lip, upper (labrale superius): The lip extending between the mouth and the supramenton.

[0609] 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.

[0610] 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.

[0611] 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.

[0612] Naso-labial angle: The angle between the columella and the upper lip, while intersecting subnasale.

[0613] Otobasion inferior: The lowest point of attachment of the auricle to the skin of the face.

[0614] Otobasion superior: The highest point of attachment of the auricle to the skin of the face.

[0615] 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.

[0616] Philtrum: the midline groove that runs from lower border of the nasal septum to the top of the lip in the upper lip region.

[0617] Pogonion: Located on the soft tissue, the most anterior midpoint of the chin.

[0618] Ridge (nasal): The nasal ridge is the midline prominence of the nose, extending from the Sellion to the Pronasale.

[0619] 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.

[0620] Sellion: Located on the soft tissue, the most concave point overlying the area of the frontonasal suture.

[0621] Septal cartilage (nasal): The nasal septal cartilage forms part of the septum and divides the front part of the nasal cavity.

[0622] Subalare: The point at the lower margin of the alar base, where the alar base joins with the skin of the superior (upper) lip.

[0623] Subnasal point: Located on the soft tissue, the point at which the columella merges with the upper lip in the midsagittal plane.

[0624] Supramenton: The point of greatest concavity in the midline of the lower lip between labrale inferius and soft tissue pogonion

[0625] Anatomy of the skull

[0626] Frontal bone: The frontal bone includes a large vertical portion, the squama frontalis, corresponding to the region known as the forehead.

[0627] Mandible: The mandible forms the lower jaw. The mental protuberance is the bony protuberance of the jaw that forms the chin.

[0628] 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.

[0629] 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.

[0630] 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.

[0631] 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.

[0632] Orbit: The bony cavity in the skull to contain the eyeball.

[0633] Parietal bones: The parietal bones are the bones that, when joined together, form the roof and sides of the cranium.

[0634] 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.

[0635] Zygomatic bones: The face includes two zygomatic bones, located in the upper and lateral parts of the face and forming the prominence of the cheek.5.9.4.1 Anatomy of the respiratory system

[0636] Diaphragm: A sheet of muscle that extends across the bottom of the rib cage. The diaphragm separates the thoracic cavity, containing the heart, lungs and ribs, from the abdominal cavity. As the diaphragm contracts the volume of the thoracic cavity increases and air is drawn into the lungs.

[0637] Larynx: The larynx, or voice box houses the vocal folds and connects the inferior part of the pharynx (hypopharynx) with the trachea.

[0638] Lungs: The organs of respiration in humans. The conducting zone of the lungs contains the trachea, the bronchi, the bronchioles, and the terminal bronchioles. The respiratory zone contains the respiratory bronchioles, the alveolar ducts, and the alveoli.

[0639] Nasal cavity: The nasal cavity (or nasal fossa) is a large air filled space above and behind the nose in the middle of the face. The nasal cavity is divided in two by a vertical fin called the nasal septum. On the sides of the nasal cavity are three horizontal outgrowths called nasal conchae (singular "concha") or turbinates. To the front of the nasal cavity is the nose, while the back blends, via the choanae, into the nasopharynx.

[0640] Pharynx: The part of the throat situated immediately inferior to (below) the nasal cavity, and superior to the oesophagus and larynx. The pharynx is conventionally divided into three sections: the nasopharynx (epipharynx) (the nasal part of the pharynx), the oropharynx (mesopharynx) (the oral part of the pharynx), and the laryngopharynx (hypopharynx).5.9.5 Patient interface

[0641] 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.

[0642] Headgear: Headgear will be taken to mean a form of positioning and stabilising structure designed to hold a device, e.g., a mask, on a head.

[0643] Plenum chamber: a mask plenum chamber will be taken to mean a portion of a patient interface having walls at least partially enclosing a volume of space, the volume having air therein pressurised above atmospheric pressure in use. A shell may form part of the walls of a mask plenum chamber.

[0644] 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.

[0645] Vent: (noun): A structure that allows a flow of air from an interior of the mask, or conduit, to ambient air for clinically effective washout of exhaled gases. For example, a clinically effective washout may involve a flow rate of about 10 litres per minute to about 100 litres per minute, depending on the mask design and treatment pressure.5.9.6 Shape of structures

[0646] Products in accordance with the present technology may comprise one or more three-dimensional mechanical structures, for example a mask cushion or an impeller. The three-dimensional structures may be bounded by two-dimensional surfaces. These surfaces may be distinguished using a label to describe an associated surface orientation, location, function, or some other characteristic. For example a structure may comprise one or more of an anterior surface, a posterior surface, an interior surface and an exterior surface. In another example, a seal-forming structure may comprise a face-contacting (e.g. outer) surface, and a separate non-face-contacting (e.g. underside or inner) surface. In another example, a structure may comprise a first surface and a second surface.

[0647] To facilitate describing the shape of the three-dimensional structures and the surfaces, we first consider a cross-section through a surface of the structure at a point, p. See Fig. 3B to Fig. 3F, which illustrate examples of cross-sections at point p on a surface, and the resulting plane curves. Figs. 3B to 3F also illustrate an outward normal vector at p. The outward normal vector at p points away from the surface. In some examples we describe the surface from the point of view of an imaginary small person standing upright on the surface.5.9.6.1 Curvature in one dimension

[0648] The curvature of a plane curve at p may be described as having a sign (e.g. positive, negative) and a magnitude (e.g. 1 / radius of a circle that just touches the curve at p).

[0649] Positive curvature: If the curve at p turns towards the outward normal, the curvature at that point will be taken to be positive (if the imaginary small person leaves the point p they must walk uphill). See Fig. 3B (relatively large positive curvature compared to Fig. 3C) and Fig. 3C (relatively small positive curvature compared to Fig. 3B). Such curves are often referred to as concave.

[0650] Zero curvature: If the curve at p is a straight line, the curvature will be taken to be zero (if the imaginary small person leaves the point p, they can walk on a level, neither up nor down). See Fig. 3D.

[0651] Negative curvature: If the curve at p turns away from the outward normal, the curvature in that direction at that point will be taken to be negative (if the imaginary small person leaves the point p they must walk downhill). See Fig. 3E (relatively small negative curvature compared to Fig. 3F) and Fig. 3F (relatively large negative curvature compared to Fig. 3E). Such curves are often referred to as convex.5.9.6.1 Curvature of two dimensional surfaces

[0652] A description of the shape at a given point on a two-dimensional surface in accordance with the present technology may include multiple normal cross-sections. The multiple cross-sections may cut the surface in a plane that includes the outward normal (a “normal plane”), and each cross-section may be taken in a different direction. Each cross-section results in a plane curve with a corresponding curvature. The different curvatures at that point may have the same sign, or a different sign. Each of the curvatures at that point has a magnitude, e.g. relatively small. The plane curves in Figs. 3B to 3F could be examples of such multiple cross-sections at a particular point.

[0653] Principal curvatures and directions: The directions of the normal planes where the curvature of the curve takes its maximum and minimum values are called the principal directions. In the examples of Fig. 3B to Fig. 3F, the maximum curvature occurs in Fig. 3B, and the minimum occurs in Fig. 3F, hence Fig. 3B and Fig. 3F are cross sections in the principal directions. The principal curvatures at p are the curvatures in the principal directions.

[0654] Region of a surface: A connected set of points on a surface. The set of points in a region may have similar characteristics, e.g. curvatures or signs.

[0655] Saddle region: A region where at each point, the principal curvatures have opposite signs, that is, one is positive, and the other is negative (depending on the direction to which the imaginary person turns, they may walk uphill or downhill).

[0656] Dome region: A region where at each point the principal curvatures have the same sign, e.g. both positive (a “concave dome”) or both negative (a “convex dome”).

[0657] Cylindrical region: A region where one principal curvature is zero (or, for example, zero within manufacturing tolerances) and the other principal curvature is non-zero.

[0658] Planar region: A region of a surface where both of the principal curvatures are zero (or, for example, zero within manufacturing tolerances).

[0659] Edge of a surface: A boundary or limit of a surface or region.

[0660] Path: In certain forms of the present technology, ‘path’ will be taken to mean a path in the mathematical - topological sense, e.g. a continuous space curve from f(0) to f(l) on a surface. In certain forms of the present technology, a ‘path’ may be described as a route or course, including e.g. a set of points on a surface. (The path for the imaginary person is where they walk on the surface, and is analogous to a garden path).

[0661] Path length: In certain forms of the present technology, ‘path length’ will be taken to mean the distance along the surface from f(0) to f(l), that is, the distance along the path on the surface. There may be more than one path between two points on a surface and such paths may have different path lengths. (The path length for the imaginary person would be the distance they have to walk on the surface along the path).

[0662] Straight-line distance: The straight-line distance is the distance between two points on a surface, but without regard to the surface. On planar regions, there would be a path on the surface having the same path length as the straight-line distance between two points on the surface. On non-planar surfaces, there may be no paths having the same path length as the straight-line distance between two points. (For the imaginary person, the straight-line distance would correspond to the distance ‘as the crow flies’.)5.9.6.3 Space curves

[0663] Space curves: Unlike a plane curve, a space curve does not necessarily lie in any particular plane. A space curve may be closed, that is, having no endpoints. A space curve may be considered to be a one-dimensional piece of three-dimensional space. An imaginary person walking on a strand of the DNA helix walks along a space curve. A typical human left ear comprises a helix, which is a left-hand helix, see Fig. 3Q. A typical human right ear comprises a helix, which is a right-hand helix, see Fig. 3R. Fig. 3S shows a right-hand helix. The edge of a structure, e.g. the edge of a membrane or impeller, may follow a space curve. In general, a space curve may be described by a curvature and a torsion at each point on the space curve. Torsion is a measure of how the curve turns out of a plane. Torsion has a sign and a magnitude. The torsion at a point on a space curve may be characterised with reference to the tangent, normal and binormal vectors at that point.

[0664] Tangent unit vector (or unit tangent vector): For each point on a curve, a vector at the point specifies a direction from that point, as well as a magnitude. A tangent unit vector is a unit vector pointing in the same direction as the curve at that point. If an imaginary person were flying along the curve and fell off her vehicle at a particular point, the direction of the tangent vector is the direction she would be travelling.

[0665] Unit normal vector: As the imaginary person moves along the curve, this tangent vector itself changes. The unit vector pointing in the same direction that the tangent vector is changing is called the unit principal normal vector. It is perpendicular to the tangent vector.

[0666] Binormal unit vector: The binormal unit vector is perpendicular to both the tangent vector and the principal normal vector. Its direction may be determined by a right-hand rule (see e.g. Fig. 3P), or alternatively by a left-hand rule (Fig. 30).

[0667] Osculating plane: The plane containing the unit tangent vector and the unit principal normal vector. See Figures 30 and 3P.

[0668] Torsion of a space curve: The torsion at a point of a space curve is the magnitude of the rate of change of the binormal unit vector at that point. It measures how much the curve deviates from the osculating plane. A space curve which lies in a plane has zero torsion. A space curve which deviates a relatively small amount from the osculating plane will have a relatively small magnitude of torsion (e.g. a gentlysloping helical path). A space curve which deviates a relatively large amount from the osculating plane will have a relatively large magnitude of torsion (e.g. a steeply sloping helical path). With reference to Fig. 3S, since T2>T1, the magnitude of the torsion near the top coils of the helix of Fig. 3S is greater than the magnitude of the torsion of the bottom coils of the helix of Fig. 3S

[0669] With reference to the right-hand rule of Fig. 3P, a space curve turning towards the direction of the right-hand binormal may be considered as having a righthand positive torsion (e.g. a right-hand helix as shown in Fig. 3S). A space curve turning away from the direction of the right-hand binormal may be considered as having a right-hand negative torsion (e.g. a left-hand helix).

[0670] Equivalently, and with reference to a left-hand rule (see Fig. 30), a space curve turning towards the direction of the left-hand binormal may be considered as having a left-hand positive torsion (e.g. a left-hand helix). Hence left-hand positive is equivalent to right-hand negative. See Fig. 3T.5.9.6.4 Holes

[0671] A surface may have a one-dimensional hole, e.g. a hole bounded by a plane curve or by a space curve. Thin structures (e.g. a membrane) with a hole, may be described as having a one-dimensional hole. See for example the one dimensional hole in the surface of structure shown in Fig. 31, bounded by a plane curve.

[0672] A structure may have a two-dimensional hole, e.g. a hole bounded by a surface. For example, an inflatable tyre has a two dimensional hole bounded by the interior surface of the tyre. In another example, a bladder with a cavity for air or gel could have a two-dimensional hole. See for example the cushion of Fig. 3L and the example cross-sections therethrough in Fig. 3M and Fig. 3N, with the interior surface bounding a two dimensional hole indicated. In a yet another example, a conduit may comprise a one-dimension hole (e.g. at its entrance or at its exit), and a two-dimension hole bounded by the inside surface of the conduit. See also the two dimensional hole through the structure shown in Fig. 3K, bounded by a surface as shown.5.10 OTHER REMARKS

[0673] 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 itappears in Patent Office patent files or records, but otherwise reserves all copyright rights whatsoever.

[0674] 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.

[0675] 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.

[0676] Furthermore, “approximately”, “substantially”, “about”, or any similar term used herein means + / - 5-10% of the recited value.

[0677] 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.

[0678] 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.

[0679] 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.

[0680] All publications mentioned herein are incorporated herein by reference in their entirety to disclose and describe the methods and / or materials which are the subject of those publications. The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present technology is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dates, which may need to be independently confirmed.

[0681] 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.

[0682] 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.

[0683] 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.

[0684] 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

6 CLAIMS1. A flow disruptor for a patient interface, wherein the patient interface is configured to deliver a flow of breathable gas to a patient for treatment of a respiratory disorder and comprises: a plenum chamber pressurisable to a therapeutic pressure of at least 6 cmH20 above ambient air pressure throughout a patient’s respiratory cycle in use, the plenum chamber comprising: a seal-forming structure constructed and arranged to form a seal with a region of the patient’s face surrounding at least one entrance to the patient’s airways, and a shell configured to support the sealforming structure in use, a connection port configured to receive the flow of breathable gas from a flow generator; and wherein the flow disruptor is positioned at or between the connection port and the at least one entrance to the patient’s airways, such that the flow disruptor at least partially obstructs the flow of breathable gas entering the patient’s airways.

2. The flow disruptor as claimed in claim 1, wherein the patient interface further comprises a clip, wherein the clip is configured to attach the seal-forming structure to the shell.

3. The flow disruptor as claimed in claim 2, wherein the flow disruptor is formed in or attached to the clip.

4. The flow disruptor as claimed in claim 2 or 3, wherein the flow disruptor is releasably attached to the clip.

5. The flow disruptor as claimed in claim 1, wherein the flow disruptor is formed in or attached to the shell.

6. The flow disruptor as claimed in any one of the preceding claims, wherein the flow disruptor comprises a front face which obstructs the flow of breathable gas wherein the front face obstructs less than or equal to 50% of the cross sectional area between the connection port and the patient’s airways.

7. The flow disruptor as claimed in any one of the preceding claims, wherein the flow disruptor comprises a plurality of apertures.

8. The flow disruptor as claimed in claim 7, wherein at least two of the plurality of apertures are of different sizes to each other.

9. The flow disruptor as claimed in claim 8, wherein the plurality of apertures comprises a first set of apertures wherein each aperture of the first set of apertures has a first aperture size, and a second set of apertures wherein each aperture of the second set of apertures having a second size, where the second size is greater than the first size.

10. The flow disruptor as claimed in claim 9, wherein the plurality of apertures further comprises a third set of apertures, wherein each aperture of the third set of apertures has a third size, and wherein the third size is greater than the first size and second size.

11. The flow disruptor of claim 10, wherein the third set of apertures are distal to a central axis of the flow disruptor.

12. The flow disruptor as claimed in any one of the preceding claims, wherein the flow disruptor has a wall thickness of between 1 mm and 3 mm inclusive.

13. The flow disruptor of any one of claims 1 to 5, wherein the flow disrupter comprises a bar extending between an inferior side of the shell and a superior side of the shell.

14. The flow disruptor of claim 13, wherein the bar has a V-shaped cross-section.

15. The flow disruptor of either claim 13 or claim 14, wherein the bar is formed from two arms each having a first end and a second end, wherein the respective first ends are connected at a linking portion.

16. The flow disruptor of claim 15, wherein the linking portion forms a leading edge of the flow disruptor.

17. The flow disruptor of either claim 15 or claim 16, where the respective second ends of the two arms each form a trailing edge of the flow disruptor.

18. The flow disruptor of any one of claims 1 to 5, wherein the flow disrupter comprises a first bar and a second bar, wherein the first bar and second bar extend between an inferior side of the shell and a superior side of the shell and define a channel therebetween said first and second bars.

19. The flow disruptor of claim 18, wherein the first bar and the second bar are arranged at an angle relative to the connection port.

20. The flow disruptor of either claim 18 or claim 19, wherein each of the first bar and second bar has a leading edge and a trailing edge.

21. The flow disruptor of claim 20, wherein the first bar and the second bar are arranged with respect to each other such that the respective leading edges are closer together than the respective trailing edges.

22. The flow disruptor of either claim 20 or claim 21, wherein the trailing edges of one or both of the first bar and the second bar are contoured or serrated.

23. The flow disruptor of any one of claims 1 to 5, wherein the flow disrupter is provided to the connection port.

24. The flow disruptor of claim 23, wherein the flow disruptor comprises at least a first arm and a second arm extending from an internal surface of the connection port into the path of the flow of breathable gas.

25. The flow disruptor as claimed in claim 24, wherein the first arm and second arm are provided to opposing internal surfaces of the connection port.

26. The flow disruptor of claim 24, wherein the flow disruptor comprises three or more arms extending from an internal surface of the connection port into the path of the flow of breathable gas.

27. The flow disruptor of claim 26, wherein the arms are arranged equidistance around the internal surface of the connection port.

28. The flow disruptor of any one of claims 24 to 27, wherein at least one of the arms of the flow disruptor is comprised of a first portion and a second portion.

29. The flow disruptor of claim 28, wherein the second portion is at an angle relative to the first portion.

30. The flow disruptor of either claim 28 or claim 29, wherein the arm includes a third portion, wherein the third portion is at an angle relative to the first portion and the second portion.

31. The flow disruptor of claim 30, wherein both the second portion of the arm and the third portion of the arm extend from the first portion of the arm.

32. The flow disruptor of claim 31, wherein the second portion of the arm is arranged to be anterior to the third portion of the arm.

33. The flow disruptor as claimed in any one of the preceding claims, wherein the flow disruptor is constructed of the same material as the seal-forming structure, the shell, or the connection port.

34. The flow disruptor as claimed in claim 33, wherein the material is silicone or polycarbonate.

35. A patient interface configured to deliver a flow of breathable gas to a patient for treatment of a respiratory disorder and comprising: a plenum chamber pressurisable to a therapeutic pressure of at least 6 cmH20 above ambient air pressure throughout a patient’s respiratory cycle in use, the plenum chamber comprising: a seal -forming structure constructed and arranged to form a seal with a region of the patient’s face surrounding at least one entrance to the patient’s airways, and a shell configured to support the seal-forming structure in use, a connection port configured to receive the flow of breathable gas from a flow generator; and a flow disruptor as claimed in any one of claims 1 to 34.

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