Device for retaining humidity in a patient interface

Abstract

Disclosed are heat and moisture exchangers for use in treatment of sleep disordered breathing. In some examples the heat and moisture exchangers may be positioned within the plenum chamber of a patient interface, an air circuit connected to the patient interface or within a conduit of a positioning and stabilising structure. In examples the heat and moisture exchanger is configured to provide a pressure drop of less than 5 cm of H2O, when measured at a flow rate of 100 litres per minute, while maintaining a humidity level of inhaled air which is 10 mg / L or greater.

Description

DEVICE FOR RETAINING HUMIDITY IN A PATIENT INTERFACE1 CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Australian Provisional Application No. 2023902762, filed August 28, 2023 and Australian Provisional Application No.2024900826, filed 27 March 2024, each of which are incorporated herein by reference 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] Obstructive Sleep Apnea (OSA), a form of Sleep Disordered Breathing (SDB), is characterised by events including occlusion or obstruction of the upper air passageduring 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).

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

[0008] 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.

[0009] 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.

[0010] 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 bymuscle 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.

[0011] 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.

[0012] 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 Therapy

[0013] 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.

[0014] 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 CSRand 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.

[0015] 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.2.2.3 Diagnosis and Treatment Systems

[0016] 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.

[0017] 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

[0018] 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 cmHiO relative to ambient pressure. For other forms of therapy, such as the delivery of oxygen, the patient interface may not include a seal sufficient to facilitate delivery to the airways of a supply of gas at a positive pressure of about 10 cmHiO. 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.

[0019] 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 cangive 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.

[0020] 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.

[0021] 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.

[0022] For these reasons, patient interfaces for delivery of CPAP during sleep form a distinct field.2.2.3.1.1 Seal-forming structure

[0023] 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.

[0024] 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 beknown by a variety of names by their manufacturer including nasal masks, full-face masks, nasal pillows, nasal puffs and oro-nasal masks.

[0025] A seal-forming structure that may be effective in one region of a patient’s face may be inappropriate in another region, e.g. because of the different shape, structure, variability and sensitivity regions of the patient’s face. For example, a seal on swimming goggles that overlays a patient’s forehead may not be appropriate to use on a patient’s nose.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] One form of nasal pillow is found in the Adam Circuit manufactured by Puritan Bennett. Another nasal pillow, or nasal puff is the subject of US Patent 4,782,832 (Trimble et al. , assigned to Puritan-Bennett Corporation.

[0033] 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

[0034] 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.

[0035] 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.

[0036] 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 Vent technologies

[0037] Some forms of patient interface 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 the patient interface, e.g., the plenum chamber, to an exterior of the patient interface, e.g., to ambient. 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.

[0038] ResMed Limited has developed a number of improved mask vent technologies. See International Patent Application Publication No. WO 1998 / 034,665; International Patent Application Publication No. WO 2000 / 078,381; US Patent No. 6,581,594; US Patent Application Publication No. US 2009 / 0050156; US Patent Application Publication No. 2009 / 0044808.

[0039] Table of noise of prior masks (ISO 17510-2:2007, 10 cmfUO pressure at Im)

[0040] (* one specimen only, measured using test method specified in ISO3744 inCPAP mode at 10 cmH2O)Sound pressure values of a variety of objects are listed below2.2.3.1.4 Pressurised Air Conduit

[0041] 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 is positioned on the patient’s face during use. The conduit may extend from the patient interface forwards away from the patient’s face.2.2.3.1.5 Pressurised Air Conduit used for Positioning / Stabilising the Seal- Forming Structure

[0042] 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.

[0043] 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.2.2.3.2 Respiratory Pressure Therapy (RPT) Device

[0044] Air pressure generators are known in a range of applications, e.g. industrialscale 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.

[0045] An example of the special requirements of certain RPT devices is acoustic noise.

[0046] 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 asflow therapy devices. Examples of RPT devices include a CPAP device and a ventilator. ISO 3744 in CPAP mode at 10 cmH20).

[0047] 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 non-dependent ventilation for a range of patients for treating a number of conditions such as but not limited to NMD, OHS and COPD.

[0048] 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.2.2.3.3 Humidifier

[0049] Delivery of a flow of air without humidification may cause drying of airways. The use of a humidifier with an RPT device and the patient interface produces humidified gas that minimizes drying of the nasal mucosa and increases patient airway comfort. In addition in cooler climates, warm air applied generally to the face area in and about the patient interface is more comfortable than cold air. A range of artificial humidification devices and systems are known, however they may not fulfil the specialised requirements of a medical humidifier.

[0050] 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 causediscomfort to the occupants. Furthermore medical humidifiers may have more stringent safety constraints than industrial humidifiers

[0051] 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.2.2.3.4 Heat and Moisture Exchangers (HMEs)

[0052] HME’s may be utilized in RPT therapy as a passive form of humidification. HMEs work by partially recovering heat and moisture present in exhaled gas from patients. This heat and moisture can be retained and recycled to the patient in a passive manner as a flow of breathable gas passes through the HME prior to inspiration. Thus, the use of EIME’ s can provide the needed moisture and humidity (generally recognized as >10mg / l) to most patients during RPT therapy to minimize any detrimental effects associated with RPT therapy and non-humidified ambient air while avoiding the need for a heated humidifier system. The use of a HME rather than a heated humidifier may also lower the possibility of occlusion caused by condensation in air delivery tubes. Heat and moisture exchangers are generally made up of foam, paper, or a substance capable of acting as a condensation and absorption surface. Generally, the material carries hygroscopic salts to improve the water-retaining capacity. Suitable salts include calcium chloride.

[0053] When selecting a suitable HME, careful consideration of material, swept length (thickness), flow area and internal surface area of the HME as well as integrated mask airflow or vent design is required to deliver an effective passive humidification system. These factors are important for ensuring that the right level of humidification may be reached while trying to minimise impact on the PAP therapy delivered to a patient. It is also important to ensure that the materials used meet strict biocompatibility requirements such as cytotoxicity levels. Careful consideration is also required to ensure that the materials do not degrade over time, or during thermal cycling, as any particles which may be inhaled by a patient could have negative health outcomes.

[0054] There is a need to provide passive humidification to a patient on PAP therapy while minimising the negative effect on patient therapy, inadequate CO2 washout, and reducing overall bulk and weight of the patient interface.2.2.3.5 Mandibular repositioning

[0055] A mandibular repositioning device (MRD) or mandibular advancement device (MAD) is one of the treatment options for sleep apnea and snoring. It is an adjustable oral appliance available from a dentist or other supplier that holds the lower jaw (mandible) in a forward position during sleep. The MRD is a removable device that a patient inserts into their mouth prior to going to sleep and removes following sleep. Thus, the MRD is not designed to be worn all of the time. The MRD may be custom made or produced in a standard form and includes a bite impression portion designed to allow fitting to a patient’s teeth. This mechanical protrusion of the lower jaw expands the space behind the tongue, puts tension on the pharyngeal walls to reduce collapse of the airway and diminishes palate vibration.

[0056] In certain examples a mandibular advancement device may comprise an upper splint that is intended to engage with or fit over teeth on the upper jaw or maxilla and a lower splint that is intended to engage with or fit over teeth on the upper jaw or mandible. The upper and lower splints are connected together laterally via a pair of connecting rods. The pair of connecting rods are fixed symmetrically on the upper splint and on the lower splint.

[0057] In such a design the length of the connecting rods is selected such that when the MRD is placed in a patient’s mouth the mandible is held in an advanced position. The length of the connecting rods may be adjusted to change the level of protrusion of the mandible. A dentist may determine a level of protrusion for the mandible that will determine the length of the connecting rods.

[0058] Some MRDs are structured to push the mandible forward relative to the maxilla while other MADs, such as the ResMed Narval CC™ MRD are designed to retain the mandible in a forward position. This device also reduces or minimises dental and temporo-mandibular joint (TMJ) side effects. Thus, it is configured to minimises or prevent any movement of one or more of the teeth.2.2.4 Screening, Diagnosis, and Monitoring Systems

[0059] Polysomnography (PSG) is a conventional system for diagnosis and prognosis of cardio-pulmonary disorders. PSG typically involves the placement of 15 to 20 contact sensors on a person in order to record various bodily signals such as electroencephalography (EEG), electrocardiography (ECG), electrooculograpy (EOG), etc. However, while they may be suitable for their usual application in a clinical setting,such systems are complicated and potentially expensive, and / or may be uncomfortable or impractical for a patient at home trying to sleep.

[0060] The designer of a device may be presented with an infinite number of choices to make to design a product or system. Design criteria often conflict, meaning that certain design choices are far 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.3 BRIEF SUMMARY OF THE TECHNOLOGY

[0061] 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.

[0062] A first aspect of the present technology relates to apparatus used in the screening, diagnosis, monitoring, amelioration, treatment or prevention of a respiratory disorder.

[0063] Another aspect of the present technology relates to methods used in the screening, diagnosis, monitoring, amelioration, treatment or prevention of a respiratory disorder.

[0064] 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.

[0065] Another aspect of the present technology is directed to a patient interface for providing a flow of pressurized, breathable gas to a patient’s airways for the treatment of a respiratory disorder. The patient interface may comprise a seal-forming structure to form pneumatic seal with the entrance to the patient’s airways, a plenum chamber, a device or insert positioned within the plenum chamber to divide the plenum chamber into an anterior chamber and a posterior chamber, wherein the device or insert comprises a plurality of apertures to allow gas to flow between the anterior chamber and the posterior chamber, and wherein, the plurality of apertures may comprise a first set of apertures of a first size, and a second set of apertures of a second size, the second size being greater than the first size.

[0066] One form of the present technology comprises a patient interface comprising a device comprising at least one aperture, the device having a predetermined surface area, the device comprising at least one aperture having a predetermined size; the device beingpositioned along a flow path of the flow of breathable gas; wherein the predetermined size of the at least one aperture and the predetermined surface area of the device are selected such that in the pressure drop through the device, when measured at a flow rate of lOOL / min is less than 5 cmHiO.

[0067] In an example, the flow may be directed away from the mucosal surface. The flow may be directed away from the mucosal surface by changing the flow from a turbulent flow to a laminar flow. By directing the predetermined amount of breathable gas through the at least one aperture to change a turbulent flow to a laminar flow, a rate of heat and water loss from the mucosal surface may be reduced. During RPT treatment, a turbulent flow of the flow of breathable gas delivered to the mucosal surface of the patient’s airways may result in evaporation of moisture on the surface and ultimately cause drying. Drying of the mucosal surface affects breathing comfort. It is the desire of the present technology to provide a patient interface comprising a device to prevent drying on the mucosal surface of a patient’s airways during RPT treatment to promote breathing comfort. The device may alter the flow of breathable gas being delivered to the patient such that the flow converts from a turbulent flow to a more laminar flow, or a less turbulent flow, which results in reduced evaporation at the mucosal surface. The device may act by directing air through apertures that are sized to allow the appropriate amount of breathable gas to flow through to provide RPT treatment to induce the desired reduction in turbulence. The apertures may also be sized to change the flow of breathable gas from a turbulent flow to a laminar flow to a sufficient level such that the rate of heat and moisture loss from the mucosal surface is reduced. The device may also comprise a large enough surface area to direct enough of the breathable through the apertures. It is also desirable to prevent drying at the mucosal surface of a patient’s airways to a sufficient level that breathing comfort is maintained without the need for a HME or any other added humidification, e.g., via a humidifier .

[0068] In another aspect of the present technology, the number and size of the apertures may be selected such that a flow of the breathable gas may be directed through the apertures within a predetermined pressure range set by the RPT device to ensure that occlusions of the patient’s airways can be reduce or minimized in spite of the increased flow impedance that may be imparted by the presence of the device in the flow path. In a further aspect of the present technology, the device may be provided with a first set of apertures having an aperture diameter of between 0.05 mm and 1 mm, and a second set of apertures having an aperture diameter of between 1 mm and 5mm, the second set ofapertures being dimensioned and positioned to increase the rate of CO2 washout within the patient interface, reduce the rate of CO2 rebreathing by the patient, and / or reduce the flow impedance caused by the device.

[0069] Another aspect of one form of the present technology is the patient interface further comprising an elbow in fluid communication with the connection port and wherein the device is positioned within the elbow. In a further aspect of one form of the present technology, the connection port may be in fluid connection to an air delivery conduit for delivery of the flow of breathable gas and wherein the device may be positioned within the air delivery conduit in the flow path of the flow of breathable gas. It is the desire of the present technology to provide a device that may be positioned anywhere in the flow path of the flow of breathable gas during RPT treatment to reduce a turbulence of the flow of breathable gas towards a mucosal surface of a patient’s airways.

[0070] Another aspect of one form of the present technology is the patient interface further comprising a connection port and wherein the device is positioned in a spaced relationship relative to the connection port. In a further aspect of one form of the present technology, device may be positioned between 1 mm and 10 mm from the connection port.

[0071] Another aspect of one form of the present technology a predetermined surface area of the device is selected to direct all the flow of breathable gas through the aperture. It is the desire of the present technology to physically interfere with and direct a laminar flow of the flow of breathable gas on the mucosal surface of a patient’s airways to prevent evaporation at the surface and ultimately prevent drying.

[0072] Another aspect of one form of the present technology the device materials, size and configuration may be selected to maintain the moisture concentration of the air inhaled by the patient at a level of lOmg / L or greater. For example, in one example the device 6000 may be configured to maintain a moisture concentration in the inhaled air of 15mg / L or greater, or in some examples a moisture concentration of 18mg / L or greater.

[0073] Another aspect of one form of the present technology provides a heat and moisture exchanging device which comprises a material which is coated, bonded with or otherwise impregnated with a humidification agent configured to encourage condensation to form on the surface of the material. In some aspects of the technology, the humidification agent is polyethylene glycol or calcium chloride. In some aspects, thematerial may comprise approximately a humidification agent percentage of approximately 2% to 20%.

[0074] Another aspect of one form of the present technology provides a heat and moisture exchanging device which comprises an open-celled hygroscopic or hydrophilic foam, such as a polyurethane foam.

[0075] In some examples the device may be configured to have a foam comprising between approximately 30 and 150 pores per inch (PPI) inclusive, such as between approximately 40 PPI and 80 PPI, such as approximately 60 PPI.

[0076] Another aspect of one form of the present technology is a system for treatment of a respiratory illness, comprising a patient interface, an air circuit and a heat and moisture exchanging device, wherein in use the air circuit delivers of a flow of breathable gas to the airways of a patient for treatment of the respiratory illness and the patient interface is configured to maintain a therapy pressure in a range of about 4 cmH20 to about 30 cmH20 above ambient air pressure.

[0077] In examples, the heat and moisture exchanging device may be provided in or attached to a connection port on the patient interface.

[0078] In other examples, the heat and moisture exchanging device may be provided in or attached to the air circuit.

[0079] In examples, the system may comprise one or more headgear tubes, and wherein the heat and moisture exchanging device may be provided in the one or more headgear tubes.

[0080] In examples, the system may comprise one or more headgear tubes, and the headgear tubes comprise an inlet configured to receive a flow of breathable gas in use, wherein the heat and moisture exchanging device may be provided in or attached to the inlet.

[0081] In other examples, the patient interface may comprise one or more plenum chamber inlet ports, wherein the heat and moisture exchanging device may be provided in or attached to the plenum chamber inlet ports.

[0082] Another aspect of one form of the present technology is a patient interface that comprises a vent for washout of exhaled air from the patient interface. The device may be positioned in a flow path of the flow of breathable gas between the vent and the entrance of a patient’s airways, when in use. Preferably, the device may be positioned in close proximity to a patient’s airways to maximise its effect on the physical interference of the flow of breathable gas.

[0083] Another aspect of one form of the present technology is the patient interface further comprises a plenum chamber separated by the device, into a first anterior chamber and a second posterior chamber configured to be in fluid communication with the entrance of the patient’s airways. The device may be positioned within the plenum chamber such that it spans an entire cross sectional surface area of the plenum chamber. The device may be positioned within the plenum chamber to minimise its impedance of the flow of breathable gas as the plenum chamber may have a larger volume for housing the device in comparison to the connection port, conduit or elbow.

[0084] Another aspect of one form of the present technology is directed to the device, wherein the device physically interferes with a flow of expiratory gas to increase the humidity in the second posterior chamber to a predetermined absolute humidity. The predetermined absolute humidity may be greater than 10 mg / L. It is desirable to provide a device to physically interfere with the flow of expiratory gas to retain the moisture in the second posterior chamber of the patient interface such that the moisture is in close proximity to the entrance of a patient’s airways for redelivery. It is also desirable to provide a level of moisture is equivalent to a predetermined absolute humidity that is sufficient to prevent drying of the mucosal surface in a patient’s airways to prevent breathing discomfort.

[0085] It should be understood that the increase in absolute humidity, as compared to a patient interface without the device, may be the result of the device reducing humidity loss from the second, posterior chamber. The absolute humidity in the second, posterior chamber is increased by expiration by the patient expiring gas humidified by the mucosal surfaces of the patient’s airways and the loss of this moisture may be caused by venting the humidified gas from the plenum chamber.

[0086] Another aspect of one form of the present technology is the device comprising at least one aperture having a predetermined size, and wherein the predetermined size of the at least one aperture is selected to such that the predetermined amount of the breathable gas flows through the aperture to deliver the flow of breathable gas at a predetermined level of pressure. The predetermined level of pressure may be between 2cm of H2O to 40cm of H2O. The predetermined size of the aperture may be selected to increase a permeability of the device to the flow of breathable gas. The permeability may be increased by increasing an anterior flow area of the aperture. The anterior flow area is the surface area of the device on an anterior side of the device facing away from the entrance to the patient’s airways. The permeability of the device may also be increasedby increasing the number of apertures. It is desirable to provide a device that does not significantly impede the flow of breathable gas to maintain a predetermined pressure level. Pressure levels in RPT treatment and particularly for PAP therapy in the treatment of OSA and other SDB conditions requires a set therapeutic level of pressure delivered to the entrance airways. Thus, it is also desirable to provide a device comprising apertures to prevent a significant pressure loss when a pressurised flow of breathable gas is delivered to the patient interface, such that a therapeutic level of pressure is maintained and delivered to the entrance of the patient’s airways.

[0087] Another aspect of one form of the present technology is directed towards the device comprising apertures having the predetermined size selected to allow a flow of expiratory gas through the aperture for a predetermined level of CO2 washout through the vent. The apertures may comprise an inner surface profile configured to direct the flow of expiratory gas towards the vent for CO2 washout. The predetermined size of the aperture may be selected to increase a permeability of the device to the flow of expiratory gas for CO2 washout. The permeability may be increased by increasing a posterior flow area of the aperture. The posterior flow area of the apertures may be increased by increasing the size of the aperture on a posterior side of the device. The permeability of the device may also be increased by increasing the number of apertures. It is desirable to provide a device that does not impede the flow of expiratory gas for sufficient CO2 washout. Impeding the flow of expiratory gas to the vent for CO2 washout results in the increase of CO2 concentrations in the patient interface and will effectively result in CO2 rebreathing. Thus, it is also desirable to provide a device comprising apertures for expiratory gas flow through, wherein the device has an increased permeability to the flow of expiratory gas for sufficient CO2 washout.

[0088] Another aspect of one form of the present technology is the device, wherein the device a flexible membrane sheet. Alternatively, the device is a textile formed of woven fibres and wherein the fibres form a plurality of the apertures between adjacent fibres. The device may also be a mesh structure. The device may be a thin flexible structure that does not occupy a significant volume along the flow path of RPT treatment, such as within the plenum chamber of the patient interface. The thin structure allows for reduced flow impedance during RPT treatment and also allows easier positioning of the device in a fixed volume of space along the flow path. Moreover, the flexibility of the device allows for ease in manipulating the device to conform to the inner volume of a patient interface.

[0089] Another aspect of one form of the present technology is the device, wherein the device has a reduced thickness to reduce a flow impedance of the flow breathable gas. The thickness may be in the range of about 0.5 cm to 1cm. The thickness may alternatively be in the range of 1mm to 0.5 cm. The thickness may be less than 1mm. A thinner device may occupy a smaller volume within the plenum chamber of the patient interface, reducing its impact on flow impedance and its impact on occupying the volume needed to accommodate a portion of the patient’s face. Thus, it is desirable to provide a device that has a reduced thickness to reduce the impact on flow impedance on the flow of breathable gas and the flow of expiratory gas and effectively reduce the volume in which the device occupies within the plenum chamber. It is also desirable to provide a device that effectively reduces drying of the mucosal surface of a patient’s airways, while having less flow impedance and occupying a smaller volume in a patient interface when compared to a HME. A HME is heat and moisture absorbent and therefore requires a volume of absorbent substrate to be able to capture the desired level of humidity. In contrast, it is also a desire of the present technology to prevent drying of the mucosal surface of the patient’s airways and redeliver humidity from expiratory gas to the patient without the need to a heat and moisture absorbent material.

[0090] Another aspect of the present technology is directed to a patient interface for sealed delivery of a flow of air at a continuously positive pressure with respect to ambient air pressure to an entrance to the patient’s airways including at least an entrance of a patient’s nares, wherein the patient interface is configured to maintain a therapy pressure in a range of about 4 cmH20 to about 30 cmH20 above ambient air pressure in use, throughout the patient’s respiratory cycle, while the patient is sleeping, to ameliorate sleep disordered breathing. The patient interface may comprise: a seal-forming structure to form a pneumatic seal with the entrance to the patient’s airways; a positioning and stabilising structure to maintain the seal-forming structure in sealing contact with an area surrounding the entrance to the patient’s airways while maintaining a therapeutic pressure at the entrance to the patient’s airways; a plenum chamber pressurised at a pressure above ambient pressure in use; a connection port for the delivery of the flow of breathable gas into the patient interface; and a device having a predetermined surface area comprising at least one aperture having a predetermined size; the device positioned along a flow path of breathable gas to physically interfere with the flow; wherein the predetermined size of the at least one aperture and the predetermined surface area of the device are selected such that a predetermined amount of breathable gas flows through theat least one aperture; and wherein the device is heat non-absorbent and moisture nonabsorbent and the device changes the flow of breathable gas flowing towards a mucosal surface of the patient’s airways from a turbulent flow to a laminar flow by directing the predetermined amount of breathable gas through the at least one aperture such that a rate of heat and water loss from the mucosal surface is reduced.

[0091] In examples, (a) the patient interface may further comprise an elbow in fluid communication with the connection port and wherein the device is positioned within the elbow, (b) the patient interface may further comprise an air delivery conduit for delivering the flow of breathable gas to the patient interface, the air delivery conduit in fluid communication with the connection port and wherein the device is positioned within the conduit, (c) the patient interface may further comprise a gas washout vent configured to allow a flow of patient exhaled CO2 to an exterior of the patient interface to minimise rebreathing of exhaled CO2 by the patient, (d) the device may be positioned in a flow path of the flow of breathable gas between the vent and the entrance of the patient’s airways, when in use, (e) the device may be positioned within the plenum chamber such that the plenum chamber is divided into a first anterior chamber and a second posterior chamber, the second posterior chamber being proximal to the entrance of the patient’s airways relative to the first anterior chamber, (f) the device may physically interfere with a flow of expiratory gas to increase the humidity in the second posterior chamber to a predetermined absolute humidity, (g) the device may physically interfere with the flow of expiratory gas by decelerating the flow of expiratory gas to the first anterior chamber for redelivery to the entrance of the patient’s airways, (h) the predetermined absolute humidity may be greater than 10 mg / L, (i) the predetermined size of each at least one aperture may be selected to substantially maintain a predetermined level of pressure when the flow of breathable gas flows through the aperture, (j) the predetermined level of pressure may be between 2 cm of H2O to 40 cm of H2O, (k) the predetermined size of the at least one aperture may be selected to maintain the predetermined pressure level by increasing a permeability of the device to the flow of breathable gas, (1) the permeability may be increased by increasing an anterior flow area of the aperture, (m) the anterior flow area of the aperture may be increased by increasing the size of the aperture on an anterior side of the device, (n) the at least one aperture may be a plurality of apertures and permeability of the device may be increased by increasing the number of apertures, (o) the predetermined size of the aperture may be selected to allow a flow of expiratory gas to flow through the aperturesfor a predetermined level of CO2 washout through the vent, (p) the aperture may comprise an inner surface profile configured to direct the flow of expiratory gas towards the vent for CO2 washout, (q) the predetermined size of the aperture may be selected to increase a permeability of the device to the flow of expiratory gas for CO2 washout, the permeability may be increased by increasing a posterior flow area of the aperture, (r) the posterior flow area of the apertures may be increased by increasing the size of the aperture on a posterior side of the device, (s) the at least one apertures may comprise a plurality of apertures and the permeability of the device may be increased by increasing the number of apertures, (t) the device may be a flexible membrane sheet, (u) the device may be a textile formed of woven fibres and the fibres may form a plurality of the apertures between adjacent fibres, (v) the device may be a mesh structure, (w) the device may comprise a material from any one of the group consisting of: synthetic materials, thermoplastic elastomers or hydrophobic polymers, (x) the device may have a predetermined thickness selected to reduce a flow impedance of the flow breathable gas, (y) the predetermined thickness of the device may be in the range of about 0.5 cm to 1 cm, (z) the predetermined thickness of the device may be in the range of about 1 mm to 0.5 cm, (aa) the predetermined thickness of the device may be less than 1mm, and / or (bb) the predetermined size of the device may be selected to fit within the plenum chamber of the patient interface.

[0092] Another aspect of the present technology is directed to a patient interface for sealed delivery of a flow of air at a continuously positive pressure with respect to ambient air pressure to an entrance to the patient’s airways including at least an entrance of a patient’s nares, wherein the patient interface is configured to maintain a therapy pressure in a range of about 4 cmH20 to about 30 cmH20 above ambient air pressure in use, throughout the patient’s respiratory cycle, while the patient is sleeping, to ameliorate sleep disordered breathing. The patient interface may comprising: a seal-forming structure to form a pneumatic seal with the entrance to the patient’s airways; a positioning and stabilising structure to maintain the seal-forming structure in sealing contact with an area surrounding the entrance to the patient’s airways while maintaining a therapeutic pressure at the entrance to the patient’s airways; a plenum chamber pressurised at a pressure above ambient pressure in use; a connection port for the delivery of the flow of breathable gas into the patient interface; and a device positioned within a breathing chamber defined, at least in part, by the seal-forming structure and the plenum chamber when the seal-forming structure is in sealing contact with the areasurrounding the entrance to the patient’s airways, wherein the device divides the breathing chamber into a posterior chamber and an anterior chamber, and wherein the device comprises a plurality of apertures such that turbulence of the air in the posterior chamber is less than turbulence in the air in the anterior chamber.

[0093] In examples, (a) the device may be positioned, shaped, and dimensioned such that the air in the breathing chamber moving between the posterior chamber and the anterior chamber only passes through the plurality of apertures, (b) the device may be shaped and dimensioned such that at least a portion of an outer peripheral edge region of the device substantially conforms to an internal surface of at least one of the sealforming structure and the plenum chamber, (c) the outer peripheral edge region may form a pneumatic seal against the internal surface of at least one of the seal-forming structure and the plenum chamber, (d) the entire outer peripheral edge region of the device may substantially conform to the internal surface of at least one of the sealforming structure and the plenum chamber, (e) the patient interface may further comprise at least one gap between the outer peripheral edge region of the device and the internal surface of at least one of the seal-forming structure and the plenum chamber, (f) at least a portion of the outer peripheral edge region of the device may be fixedly attached to the internal surface of at least one of the seal-forming structure and the plenum chamber, (g) at least a portion of the outer peripheral edge region of the device may be removably attached to the internal surface of at least one of the seal-forming structure and the plenum chamber, (h) the plurality of apertures may be uniform in at least one of size, shape, and density across the entire device, (i) the plurality of apertures may not be uniform in at least one of size, shape, and density across the entire device, (j) each of the plurality of apertures may have a posterior area adjacent to the posterior chamber and an anterior area adjacent to the anterior chamber, (k) the posterior area of each of the plurality of apertures may be greater than, less than, or equal to the anterior area of each of the plurality of apertures, (1) a flow path through each of the plurality of apertures may be linear or non-linear, (m) the device may comprise a material that is resistant to absorption of moisture and / or heat, (n) the material may be any one of the group consisting of nylon, polycarbonate, silicone, polyurethane, thermoplastic elastomers, hydrophobic polymers, and other synthetic materials, (o) the device may comprise a single, continuous, and homogeneous piece of the material, (p) the device may have a mesh, foam, or woven structure, (q) the device may be positioned within the breathing chamber such that the volume of the posterior chamber is greater than, less than, or equalto the volume of the anterior chamber, (r) the patient interface may further comprise a vent to washout gas from the patient interface, (s) the vent may be positioned on the plenum chamber or an elbow of the patient interface such that gas from the anterior chamber is washed out via the vent, and / or (t) the vent and the connection port may be positioned opposite the entrance to patient’s airways relative to the device.

[0094] 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.

[0095] 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

[0096] 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

[0097] Fig. 1A 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.

[0098] 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.

[0099] 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

[0100] Fig. 2A shows an overview of a human respiratory system including the nasal and oral cavities, the larynx, vocal folds, oesophagus, trachea, bronchus, lung, alveolar sacs, heart and diaphragm.

[0101] Fig. 2B shows a view of a human upper airway including the nasal cavity, nasal bone, lateral nasal cartilage, greater alar cartilage, nostril, lip superior, lip inferior, larynx, hard palate, soft palate, oropharynx, tongue, epiglottis, vocal folds, oesophagus and trachea.

[0102] Fig. 2C is a front view of a face with several features of surface anatomy identified including the lip superior, upper vermilion, lower vermilion, lip inferior, mouth width, endocanthion, a nasal ala, nasolabial sulcus and cheilion. Also indicated are the directions superior, inferior, radially inward and radially outward.

[0103] Fig. 2D is a side view of a head with several features of surface anatomy identified including glabella, sellion, pronasale, subnasale, lip superior, lip inferior, supramenton, nasal ridge, alar crest point, otobasion superior and otobasion inferior. Also indicated are the directions superior & inferior, and anterior & posterior.

[0104] Fig. 2E is a further side view of a head. The approximate locations of the Frankfort horizontal and nasolabial angle are indicated. The coronal plane is also indicated.

[0105] Fig. 2F shows a base view of a nose with several features identified including naso-labial sulcus, lip inferior, upper Vermilion, naris, subnasale, columella, pronasale, the major axis of a naris and the midsagittal plane.

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

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

[0108] Fig. 21 shows a medial dissection of a nose, approximately several millimeters from the midsagittal plane, amongst other things showing the septum cartilage and medial crus of greater alar cartilage.

[0109] Fig. 2J shows a front view of the bones of a skull including the frontal, nasal and zygomatic bones. Nasal concha are indicated, as are the maxilla, and mandible.

[0110] Fig. 2K shows a lateral view of a skull with the outline of the surface of a head, as well as several muscles. The following bones are shown: frontal, sphenoid,nasal, zygomatic, maxilla, mandible, parietal, temporal and occipital. The mental protuberance is indicated. The following muscles are shown: digastricus, masseter, sternocleidomastoid and trapezius.

[0111] Fig. 2L shows an anterolateral view of a nose.4.3 PATIENT INTERFACE

[0112] Fig. 3A shows a patient interface in the form of a nasal mask in accordance with one form of the present technology.

[0113] Fig. 3B shows a patient interface having conduit headgear, in accordance with one form of the present technology.4.4 RPT DEVICE

[0114] Fig. 4A shows an RPT device in accordance with one form of the present technology.

[0115] 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.

[0116] Fig. 4C is a schematic diagram of the electrical components of an RPT device in accordance with one form of the present technology.

[0117] Fig. 4D is another schematic diagram of the electrical components of an RPT device in accordance with one form of the present technology.4.5 HUMIDIFIER

[0118] Fig. 5A shows an isometric view of a humidifier in accordance with one form of the present technology.

[0119] 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.

[0120] Fig. 5C shows a schematic of a humidifier in accordance with one form of the present technology.4.6 BREATHING WAVEFORMS

[0121] Fig. 6A shows a model typical breath waveform of a person while sleeping.4.7 EXAMPLES OF THE PRESENT TECHNOLOGY

[0122] Fig. 7A shows a side view of a patient receiving a flow of pressurized, breathable from a patient interface in accordance with an example of the present technology.

[0123] Fig. 7B shows a side view of a patient receiving a flow of pressurized, breathable from a patient interface with a device in accordance with an example of the present technology.

[0124] Fig. 8A shows a side view of a patient with a patient interface that includes a device in accordance with an example of the present technology.

[0125] Fig. 8B shows a side view of a patient with a patient interface that includes a device in accordance with an example of the present technology.

[0126] Fig. 8C shows a side view of a patient with a patient interface that includes a device in accordance with an example of the present technology.

[0127] Fig. 9A shows a perspective view of an example of a device in accordance with an example of the present technology.

[0128] Fig. 9B shows a perspective view of an example of a device in accordance with an example of the present technology.

[0129] Fig. 9C shows a perspective view of a further example of a device in accordance with an example of the present technology.

[0130] Fig. 10A shows a rear view of a patient with a patient interface in accordance with an example of the present technology.

[0131] Fig. 10B shows a rear view of a patient with a patient interface that includes a device in accordance with an example of the present technology.

[0132] Fig. 11 shows a chart of the average absolute humidity in the posterior side of a device in a patient interface based on different device materials according to an example of the present technology.T1

[0133] Fig. 12A shows a front perspective view of a model of a seal-forming structure and a plenum chamber of a patient interface with a vent, a connection port, and a device in accordance with an example of the present technology.

[0134] Fig. 12B shows a front perspective view of a model of a seal-forming structure and a plenum chamber of a patient interface with a vent, a connection port, and a device in accordance with an example of the present technology.

[0135] Fig. 13A shows flow velocity modelling within the model of Figs. 12A and 12B (the device is absent) from a computational fluid dynamics program when flow produced by the patient is zero.

[0136] Fig. 13B shows flow velocity modelling within the model of Figs. 12A and 12B (the device is present) from a computational fluid dynamics program when flow produced by the patient is zero.

[0137] Fig. 14A shows flow velocity modelling within the model of Figs. 12A and 12B (the device is absent) from a computational fluid dynamics program when flow produced by the patient is lOL / min.

[0138] Fig. 14B shows flow velocity modelling within the model of Figs. 12A and 12B (the device is present) from a computational fluid dynamics program when flow produced by the patient is lOL / min.

[0139] Fig. 15A shows flow velocity streamlines modelled within the model of Figs. 12A and 12B (the device is absent) from a computational fluid dynamics program when flow produced by the patient is zero.

[0140] Fig. 15B shows flow velocity streamlines modelled within the model of Figs. 12A and 12B (the device is present) from a computational fluid dynamics program when flow produced by the patient is zero.

[0141] Fig. 16A shows flow velocity streamlines modelled within the model of Figs. 12A and 12B (the device is absent) from a computational fluid dynamics program when flow produced by the patient is lOL / min.

[0142] Fig. 16B shows flow velocity streamlines modelled within the model of Figs. 12A and 12B (the device is present) from a computational fluid dynamics program when flow produced by the patient is lOL / min.4.8 MODULARITY

[0143] Fig. 17A-1 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.

[0144] Fig. 17A-2 shows a perspective view of the cushion of Fig 17A-1 with a device in at least one plenum chamber inlet port.

[0145] Fig. 17A-3 shows a perspective view of the cushion of Fig 17A-1 with a device in at least one vent opening or connection port.

[0146] Fig. 17B-1 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.

[0147] Fig. 17B-2 shows a perspective view of the cushion of Fig 17B-1 with a device in at least one plenum chamber inlet port.

[0148] Fig. 17B-3 shows a perspective view of the cushion of Fig 17B-1 with a device in at least one vent opening or connection port.

[0149] Fig. 17C shows a perspective view of tubes usable with the cushions of Fig. 17A-1 to Fig. 17B-3.

[0150] Fig. 17D shows a perspective view of rigidiser arms usable with the cushions of Fig. 17A-1 to Fig. 17B-3.

[0151] Fig. 17E shows a perspective view of headgear straps usable with the cushion of Fig. 17A-1.

[0152] Fig. 17F shows a perspective view of headgear straps usable with the cushion of Fig. 17B-1.

[0153] Fig. 17G shows a front view of a pair of sleeves that is removably fitted to either the tubes of Fig. 17C or the rigidiser arms of Fig. 17D.

[0154] Fig. 17H shows a front view of a full sleeve that is removably fitted to the rigidiser arms of Fig. 17D.

[0155] Fig. 171 shows a front perspective view of yet another alternate form of a full sleeve that is removably fitted to the rigidiser arms of Fig. 17D.

[0156] Fig. 17J-1 is a front view of a patient wearing the cushion of any one of Figs. 17A-1 to 17A-3 connected to the tubes of Fig. 17C, the headgear straps of Fig. 17E, and the sleeves of Fig. 17G.

[0157] Fig. 17J-2 is a front view of a patient wearing the cushion of any one of Figs. 17A-1 to 17A-3 connected to the tubes of Fig. 17C, the headgear straps of Fig. 17E, and the sleeves of Fig. 17G together with a device in an inlet.

[0158] Fig. 17K is a front view of a patient wearing the cushion of Fig. 17A-1 or 17A-3 connected to the rigidiser arms of Fig. 17D, the headgear straps of Fig. 17E, and the sleeve of Fig. 17H.

[0159] Fig. 17L is a front view of a patient wearing the cushion of any one of Figs. 17B-1 to 17B-3 connected to the conduit headgear of Fig. 17C, and the headgear straps of Fig. 17F.

[0160] Fig. 17M is a front view of a patient wearing the cushion of Fig. 17B-1 or Fig. 17B-3 connected to the rigidisier arms of Fig. 17D, the headgear straps of Fig. 17F, and the sleeve of Fig. 171.

[0161] Fig. 17N is an isolated perspective view of the vent of Fig. 17L.

[0162] Fig. 170 is an isolated perspective view of a portion of the air circuit of Fig.17M.

[0163] Fig. 17P is a schematic view illustrating the possible combinations of the patient interfaces.DETAILED DESCRIPTION OF EXAMPLES OF THE TECHNOLOGY

[0164] 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.

[0165] The following description is provided in relation to various examples which may share one or more common characteristics and / or features. It is to be understood that one or more features of any one example may be combinable with one or more features of another example or other examples. In addition, any single feature or combination of features in any of the examples may constitute a further example.5 DETAILED DESCRIPTION OF THE TECHNOLOGY

[0166] 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 isfor the purpose of describing only the particular examples discussed herein, and is not intended to be limiting.

[0167] The following description is provided in relation to various examples which may share one or more common characteristics and / or features. It is to be understood that one or more features of any one example may be combinable with one or more features of another example or other examples. In addition, any single feature or combination of features in any of the examples may constitute a further example.5.1 THERAPY

[0168] In one form, the present technology comprises a method for treating a respiratory disorder comprising the step of applying positive pressure to the entrance of the airways of a patient 1000.

[0169] 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.

[0170] In certain examples of the present technology, mouth breathing is limited, restricted or prevented.5.2 TREATMENT SYSTEMS

[0171] In one form, the present technology comprises an apparatus or device for treating a respiratory disorder. The apparatus or device may comprise an RPT device 4000 for supplying pressurised air to the patient 1000 via an air circuit 4170 to a patient interface 3000.5.3 PATIENT INTERFACE

[0172] A non-invasive patient interface 3000 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 and one form of connection port 3600 for connection to air circuit 4170. 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 facilitate the supply of air at positive pressure to the airways.5.3.1 Seal-forming structure

[0173] In one form of the present technology, a seal-forming structure 3100 provides a seal-forming surface, and may additionally provide a cushioning function.

[0174] A seal-forming structure 3100 in accordance with the present technology may be constructed from a soft, flexible, resilient material such as silicone.

[0175] In one form, the seal-forming structure comprises a sealing flange and a support flange. 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 3110 from buckling in use. In use the sealing flange 3110 can readily respond to system pressure in the plenum chamber 3200 acting on its underside to urge it into tight sealing engagement with the face.

[0176] In one form the seal-forming portion 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.

[0177] 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.

[0178] 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) of the patient's face.

[0179] In one form the non-invasive patient interface 3000 comprises a seal-forming portion that forms a seal in use on a chin-region of the patient's face.5.3.2 Plenum chamber

[0180] 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 3200.5.3.2.1 Multiple Openings

[0181] As shown in Figs. 17A-1 to 17B-3, 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.

[0182] 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.

[0183] 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.

[0184] 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 “tube-down” configuration (e.g., using a single conduit in front of the patient’s face).5.3.2.2 Nose and Mouth Mask

[0185] As shown in Figs. 17A-1 to 17A-3, 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.

[0186] In some forms, the plenum chamber 3200-1 may also include at least one vent opening 3402-1 (see e.g., Fig. 17A-1). 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.

[0187] It should be appreciated that in tube down patient interfaces 3000 such as shown in FIG. 17K the vent opening 3402-1 may be a connection port 3600 configured to connect to an air circuit 4170 in use. Similarly the plenum chamber inlet ports 3254-1 may be configured to connect to one or more straps of a positioning and stabilising structure 3300.

[0188] 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.5.3.2.3 Nose-only Mask

[0189] 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. Only some similarities and differences between the plenum chambers 3200-1, 3200-2 may be described below.

[0190] As shown in Figs. 17B-1 to 17B-3, 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.

[0191] In some forms, the plenum chamber 3200-2 may also include at least one vent opening 3402-2 or connection port 3600 (see e.g., Fig. 17B-1). 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.

[0192] 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

[0193] 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.

[0194] 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 theapparatus. 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.

[0195] In one form of the present technology, a positioning and stabilising structure 3300 comprises a strap constructed from a laminate of a fabric patient-contacting layer, a foam inner layer and a fabric outer layer. In one form, the foam is porous to allow moisture, (e.g., sweat), to pass through the strap. In one form, the fabric outer layer comprises loop material to engage with a hook material portion.

[0196] 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.

[0197] 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.5.3.3.1 Conduit headgear5.3.3.1.1 Conduit headgear tubes

[0198] 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. 17J -1 and 17J-2, the positioning and stabilising structure 3300 comprises two tubes 3350 that deliver air to the plenum chamber 3200 from an air circuit 4170 connected to the inlet 3332-1. 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.

[0199] In the form of the present technology illustrated in Fig. 17J-1 and 171-2, 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.

[0200] 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.

[0201] 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.

[0202] In the form of the technology shown in Fig. 17J-1 and 17J-2, the two tubes 3350 are fluidly connected at superior ends to each other and to the connection port 3600. In some examples a device 6000 may be provided in or otherwise connected to the connection port 3600.

[0203] 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.

[0204] 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 anothershape 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.

[0205] 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.

[0206] Each tube 3350 may be configured to receive a flow of air from the connection port 3600 or inlet 3332 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. 17J-1 and 17J-2, 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 inlet 3332-1. 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).

[0207] In certain forms of the present technology the patient interface 3000 is configured such that the connection port 3600 or inlet 3332 can be positioned in a range of positions across the top of the patient’s head so that the patient interface 3000 can be positioned as 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.

[0208] 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 cushionwhich 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.5.3.3.1.2 Extendable and non-extendable tube portions

[0209] 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 3362. 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. 17C comprises tubes 3350, the superior portions of which comprise extendable tube sections each in the form of an extendable concertina structure 3362.

[0210] In some forms, the extendable concertina structure 3362 may be formed as a series of ridges and grooves on the surface of the tubes 3350. The concertina structure 3362 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 3362 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 3362. Alternatively, the tubes 3350 may be manufactured in multiple sizes (e.g., small, medium, large). The patient may select a length that most closely conforms to their head, and the concertina structures 3362 may make small adjustments in order to tailor the fit to the individual patient.

[0211] In some forms, the inlet 3332 may be disposed in the middle of the conduit. For example, the tubes 3350 may be symmetric about the inlet 3332 through at least one axis.

[0212] 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.

[0213] In some examples of the present technology, the non-extendable tube sections 3363 connect 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

[0214] 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 3B, 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 positioning and 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 port 3600 may be located in the sagittal plane of the patient’s head in use.

[0215] In some examples of the technology, the device 6000 configured to exchange heat and / or moisture between the air exhaled by the patient and the air inhaled by the patient may be positioned in or otherwise configured to attach to the connection port 3600, for example the device 6000 may be positioned in, or otherwise configured to attach to the elbow 3610 in use.

[0216] Patient interfaces having a connection port 3600 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 seal -forming structure (where tube drag forces may be more likely to disrupt the seal).5.3.3.1.4 Headgear Tube Fluid Connections

[0217] 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 connector made, 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.

[0218] 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 airtight 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

[0219] As shown in Fig. 17F, 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).5.3.4 Vent

[0220] In one form, the patient interface 3000 includes a vent 3400 constructed and arranged to allow for the washout of exhaled carbon dioxide.

[0221] 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.

[0222] The vent 3400 may be located in the plenum chamber 3200. Alternatively, the vent 3400 is located in a decoupling structure 3500, e.g., a swivel 3510.5.3.5 Decoupling structure(s)

[0223] In one form the patient interface 3000 includes at least one decoupling structure 3500, for example, a swivel 3510 or a ball and socket.5.3.6 Connection port

[0224] Connection port 3600 allows for connection to the air circuit 4170.5.3.7 Forehead support

[0225] In one form, the patient interface 3000 includes a forehead support 3700.5.3.8 Anti-asphyxia valve

[0226] In one form, the patient interface 3000 includes an anti-asphyxia valve.5.3.9 Ports

[0227] 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 supplemental 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 Patient Interface 3000 Comprising a Device 6000

[0228] In related technologies, the patient 1000 may be provided a supply of gas generated by an RPT device 4000, as described elsewhere herein. The patient interface 3000 of these related technologies may include a vent 3400 to allow for the washout or discharge of expired gas from the patient 1000 to direct CO2 away from the patient’s airways 1004, thereby preventing the patient 1000 from inhaling gas with an undesirably high concentration of CO2. When the patient 1000 inhales the supply of gas generated by the RPT device during breathing, the mucosal surfaces of the patient’s airways 1004 provide moisture to the air as it is inhaled and the moisture is retained in the air once it isexhaled. However, the washout of the expired gas, with the higher concentration of CO2, or vent flow 7004 discharges the moisture added to the air by the patient’s mucosal surfaces along with the CO2. Over the course of a treatment session, e.g., while the patient sleeps, this may result in drying of the mucosal surfaces which may become uncomfortable for the patient.

[0229] Related technologies have addressed this issue by providing a humidifier 5000, described in greater detail elsewhere herein, to add moisture, i.e., humidify, the flow of gas 7000 provided to the patient interface 3000 for therapy. In other words, the humidifier 5000 may be understood to resupply the moisture lost through the vent flow 7004 by providing moisture in the flow of gas 7000 supplied to the patient. While a humidifier 5000 may effectively reduce the drying of the patient’s airways 1004 during therapy, the humidifier 5000 may require a source of moisture, a source of power, and control systems to coordinate operation of the humidifier 5000 with the RPT device 4000 to deliver the desired level of humidity and therapy to the patient. Therefore, it may be desirable to provide another solution to the problem of the loss of moisture during therapy without the requirements associated with the humidifier 5000.

[0230] A non-invasive patient interface 3000 in accordance with one aspect of the present technology comprises a device 6000. The device 6000 may be heat nonabsorbent or resistant to the absorption of heat and / or the device 6000 may be moisture non-absorbent or resistant to the absorption of moisture.

[0231] The device 6000 may be positioned within the plenum chamber 3200 of the patient interface 3000 in accordance with an example of the present technology. The device 6000 may also be located in a breathing chamber that is defined, at least in part, by the seal-forming structure 3100 and the plenum chamber 3200. Alternatively, the device 6000 may be positioned within the decoupling structure 3500 or an elbow of the patient interface 3000. Alternatively, the device 6000 may be positioned within the air circuit 4170. The device 6000 may be configured to direct the flow of breathable gas 7000 through at least one aperture 6002 to reduce a turbulence of the flow 7000 towards a mucosal surface of the patient’s airways 1004 to reduce drying of the mucosal surface.

[0232] The device may comprise a plurality of apertures 6002. These apertures may be formed for example during a foaming process. For example, in the production of a foams, it is common for two or more ingredients to react together to produce a gas, this gas can form a series of apertures as it expands and escapes from the mixture.

[0233] For example, in the context of polyurethane foams an isocyanate and a polyol are combined, sometimes in the presence of a catalyst or ultraviolet light. During the reaction water may be added to form carbon dioxide gas, whereby the escaping of the gas forms the one of more apertures. These apertures may be represented by an average aperture size, or more commonly in terms of pores per inch (PPI).

[0234] In aspects of the present technology, it may be desirable to have a device having apertures 6002 consisting of between approximately 30 PPI and 150 PPI inclusive, such as between approximately 40 PPI and 80 PPI, such as approximately 60 PPI. These ranges may advantageously provide a device with low impedance characteristics while simultaneously allowing for adequate moisture retention.

[0235] The device 6000 may be positioned between the connection port 3600 and the entrance 1006 of a patient’s airways 1004 such that it directs some or all of the flow of breathable gas 7000 through the apertures 6002. The device 6000 may comprise a predetermined surface area to physically interfere with and direct all of the flow 7000 through the apertures 6002. Also, the expiratory flow 7002 from the patient’s airways 1004 may be directed out of the plenum chamber 3200 by passing in the opposite direction through the apertures 6002 and out the vent 3400 as the washout or vent flow 7004.

[0236] In one form, the device 6000 may separate the plenum chamber 3200 into a first, anterior chamber 6004 and a second, posterior chamber 6006. The second, posterior chamber 6006 is positioned such that it is adjacent to the entrance 1006 of the patient’s airways 1004. The device 6000 may physically interfere with the flow of expiratory gas 7002 to increase the humidity in the second, posterior chamber 6006 to a predetermined absolute humidity for redelivering humidification to the mucosal surface of the patient’s airways 1004. The humidified flow of expiratory gas 7002 of the patient may be decelerated from flowing into the first anterior chamber 6004, thereby increasing the humidity within the second posterior chamber 6006 for redelivery to the entrance of a patient’s airways 1004. Thus, by reducing the velocity of the expiratory flow 7002 within the plenum chamber 3200, by forcing the expiratory flow 7002 to pass through the apertures 6002 from the second, posterior chamber 6006 to the first, anterior chamber 6004, the turbulence in the second, posterior chamber 6006 may be reduced. It should be understood that the device 6000 may reduce the velocity or kinetic energy of the flow 7000 by impeding its passage to the second, posterior chamber 6006, which in turn reduces turbulence in the flow. The reduction of the turbulence in the second, posteriorchamber 6006 may in turn reduce mixing between the expiratory flow 7002 and the flow of breathable gas 7000 from the RPT device 4000, which may be less humid. Thus, there may be a reduction in the loss of moisture from the expiratory flow 7002, a substantial portion of which may ultimately be retained in the second, posterior chamber 6006 and can be used to humidify air inhaled by the patient 1000 such that the patient’s airways 1004 do not dry out. Additionally, by retaining more moisture in the second, posterior chamber 6006, there is less moisture that is transferred to the first, anterior chamber 6004 that may ultimately be lost from the plenum chamber 3200 by, for example, the vent flow 7004. The absolute humidity within the second, posterior chamber 6006 may reach greater than 10 mg / L.

[0237] In one form, the seal-forming structure 3100 of the patient interface 3000 may be configured to seal on a portion of the patient’s 1000 face to provide the flow of breathable gas 7000 at a therapeutic pressure level for RPT to treat conditions such as sleep disordered breathing. The flow of breathable gas 7000 flows from the connection port 3600, into the plenum chamber 3200 and through the apertures 6002 of the device 6000 before reaching the entrance of the patient’s airways 1004. The permeability of the device 6000 to the flow of breathable gas 7000 may be increased to maintain a predetermined level of pressure when the flow of breathable gas 7000 flows through the apertures 6002 to avoid significant losses of therapeutic pressure prior to reaching the entrance of the patient’s airways 1004. The predetermined pressure level may be between 2 cm H2O to 40 cm H2O. The permeability may be increased by increasing an anterior flow area of the apertures 6002. The anterior flow area of the apertures 6002 is the area in which the apertures occupy on an anterior side of the device 6000 to allow the flow of breathable gas 7000 through the apertures 6002. The anterior flow area may be selected by selecting apertures 6002 having a predetermined size. Alternatively, the permeability of the device 6000 to the flow of breathable gas 7000 may be increased by increasing the number of apertures 6002. Thus, the area of the apertures 6002 on the anterior side of the device 6000 and the number of the apertures 6002 are two factors in determining the anterior flow area of the device 6000.

[0238] In one form, the device 6000 may be positioned between the vent 3400 and the patient 1000 such that the flow of expiratory gas 7002 flows through the apertures 6002 of the device 6000 prior to flowing out of the vent 3400 for CO2 washout as the vent flow 7004. The permeability of the device 6000 to the flow of expiratory gas 7002 may be increased to allow the flow of expiratory gas 7002 through the apertures 6002 for apredetermined level of CO2 washout. The permeability to the flow of expiratory gas 7002 may be increased by increasing a posterior flow area of the apertures 6002. The desired posterior flow area of the device 6000 may be selected by selecting apertures 6002 having a predetermined size. In addition, the permeability may be increased by increasing the number of the apertures 6002. Thus, the area of the apertures 6002 on the posterior side of the device 6000 and the number of the apertures 6002 are two factors in determining the posterior flow area of the device 6000.

[0239] In another form, the apertures 6002 may each comprise an inner surface profile configured to direct the flow of expiratory gas 7002 towards the vent 3400 for the predetermined level of CO2 washout. The predetermined level of CO2 washout or vent flow 7004 may be sufficient to prevent significant CO2 rebreathing resulting in deleterious effects such as sudden awakening during RPT in the treatment of SDB.

[0240] In one form, the device 6000 may be a flexible membrane sheet, as shown in Fig. 8A. Alternatively, the device 6000 may be a textile formed of woven fibres and wherein the fibres form a plurality of apertures 6002 between adjacent fibres, as shown in Fig. 8B. In another form, the device 6000 may be a mesh structure, as shown in Fig. 8C.

[0241] Figs. 9A and 9B show two perspective views of a device 6000 according to the present technology. The device 6000 can be seen with a number of apertures 6002. The apertures 6002 may be substantially uniform in size and shape over the entirety of the device 6000 for example each aperture may be formed to have approximately the same size using a puncturing or drilling process, or alternatively the device 6000 may be characterised by an approximate range of pores per inch, as described herein, such as approximately 60 PPI. Alternatively, the size of the apertures 6002 may be varied in different regions of the device 6000, the shape of the apertures 6002 may be varied in different regions of the device 6000, and / or the density of the apertures 6002, i.e., the number of apertures 6002 per unit area (PPI) of the surface of the device 6000, may be varied in different regions of the device 6000.

[0242] In some examples of the technology, the apertures 6002 may be formed during the manufacturing process. For example, in the process of forming a foam, the apertures may be formed by selecting an appropriate blowing agent, foam material / compo sition or controlling operational parameters such as temperature, pressure and time. In some examples of the technology, such as is shown in Fig 9C, it may be advantageous for the device 6000 to comprise a plurality of apertures 6002A configured to retain moisture,and one or more apertures 6002B configured to reduce the flow impedance of the device 6000. For example, a device 6000 may be provided which comprises a first set of apertures 6002A with a first aperture size or diameter, and a second set of apertures 6002B with a second aperture size or diameter, the second size or diameter being greater than the first size.

[0243] For example, the first set of apertures 6002A which may be configured to exchange moisture may be configured to have a diameter of between approximately 0.05 mm and approximately 1 mm such as approximately 0.1 mm to approximately 0.5 mm. In some examples the first set of apertures 6002A may comprise a plurality of different apertures between 0.05 mm and 1 mm. In some examples the first set of apertures may be characterised as having a pore density of between approximately 30 PPI and 150 PPI inclusive, such as between approximately 40 PPI and 80 PPI, such as approximately 60 PPI.

[0244] In some examples, the second set of apertures 6002B which may be configured to reduce the flow impedance, may be sized or otherwise dimensioned to reduce the total pressure drop through the device 6000 to below 5 cmFhO, when measured at an airflow rate of lOOL / minute. For example, it may be advantageous for the device 6000 to be configured to provide a pressure drop of less than 3 cmFhO or less than 1 cmfFO when measured at an airflow rate of lOOL / minute. For example, the second set of apertures 6002B may be dimensioned between approximately 1 mm and approximately 5 mm, such as between approximately 1.5 mm and approximately 3mm, such as between 2 mm and 2.5 mm. In some examples the second set of apertures may be characterised as having a pore density of less than 20 PPI.

[0245] The second set of apertures 6002B may be formed at the time that the device 6000 material is produced, for example by expanding a foam around one or more posts dimensioned to match the required size of the apertures 6002B. Alternatively, the apertures 6002B may be formed after the material has been produced, such as by a punching, drilling, or cutting process.

[0246] The apertures 6002B may be distributed around the device in an even arrangement, such as in a grid, or geometric pattern or with fixed spacing from adjacent apertures 6002B. In other examples, the apertures 6002B may be positioned to provide controlled airflow within the patient interface 3000. For example, apertures 6002B may be positioned in areas of the device 6000 in order to assist with CO2 washout, such as regions within the plenum chamber which have the lowest overall airflow rate.

[0247] Accordingly, in one example of the technology, the device 6000 may comprises a first set of apertures 6002A configured in use to exchange heat and / or moisture between the exhaled breath of a patient and the inhaled breath of a patient, and a second set of apertures which are larger than the first set of apertures, in order to reduce the flow impedance of the device. In some examples the second set of apertures may be positioned to encourage or increase the air flow rate in certain regions of a patient interface, such as in any one or more of: below the mouth of the patient, in the nasal bridge region, in one or more cheek regions, in one or more side of nose regions, and in one or more comers of the patient interface.

[0248] Furthermore, the device 6000 may be shaped such that its periphery substantially conforms to the interior surface of the plenum chamber 3200 to provide a secure fit within the patient interface 3000. The device 6000 may be secured to the interior of the plenum chamber 3200 with a friction fit, a press fit, a snap fit, adhesive, molding, and / or clips or other attachment structures. Alternatively, the device 6000 may be formed in one piece with the plenum chamber 3200 such that the device 6000 and the plenum chamber 3200 comprise a single piece of homogenous and continuous material.

[0249] According to further examples, the device 6000 may be formed of a material that is heat non-absorbent or resistant to the absorption of heat and / or the device 6000 may be moisture non-absorbent or resistant to the absorption of moisture. The material of the device 6000 may be any one of the group consisting of Nylon, polycarbonate, silicone, polyurethane, thermoplastic elastomers, hydrophobic polymers, and other synthetic materials. Alternatively, the device 6000 may comprise a material that forms a heat and moisture exchanger, such as paper. However, in this instance, the device 6000 may be too thin to effectively exchange heat and moisture to provide humidification at the predetermined level. Thus, the device 6000 may rely mostly on the ability to direct the flow of breathable gas 7000 to reduce the turbulence of the flow towards the mucosal surface of the patient’s airways 1004 to reduce drying of the mucosal surface.

[0250] In one form, the device 6000 may be less than 1 cm thick, according to an example of the present technology. According to another example of the present technology, the device 6000 may be less than 0.5 cm thick. According to another example of the present technology, the device 6000 may be less than 1 mm thick. The device 6000 may occupy a smaller volume within the plenum chamber 3200 to reduce its impact on the flow of breathable gas 7000, the flow of expiratory gas 7002 from the patient, and / or the vent flow 7004. The device 6000 may reduce the drying of themucosal surface of a patient’s airways 1004 to avoid breathing discomfort to the same effect as powered humidification or the use of a HME. However, the device 6000 will not require any external power source and the device 6000 is capable of occupying a significantly smaller size and volume when compared to an HME that may provide a similar level of breathing comfort through heat and moisture exchange. Occupying a smaller volume may have the effect of reducing impedance on the flow of breathable gas 7000 that results in pressure losses during RPT for the treatment of SDB. The smaller device 6000 may also have a reduced impedance on the flow of expiratory gas 7002 to the vent 3400 and / or the vent flow 7004 that washes out CO2. Moreover, a smaller device 6000 may allow for additional space to accommodate a portion of the patient’s face within the patient interface 3000 when compared to the use of an in-mask HME.

[0251] In one form, the device 6000 material may comprise a humidification agent. For example, the humidification agent may be coated, bonded with, or otherwise impregnated with a humidification agent configured to encourage condensation to form on the surface of the material. For example, the humidification agent may be a biocompatible hydrophilic material such as calcium chloride or polyethylene glycol. In some examples of the technology, the humidification agent may comprise between 2% and 20% of the device material.

[0252] In one form, the device 6000 may be constructed of a moulded foam material. For example, the foam may be a hygroscopic and / or hydrophilic foam. In examples the foam may be an open-celled foam. For example the device may comprise an open-celled hydroscopic and / or hydrophilic polyurethane foam.

[0253] In one form, the device 6000 may be configured to maintain a moisture concentration in the air inhaled by the patient of 10 mg / L or greater. For example, in one example the device 6000 may be configured to maintain a moisture concentration in the inhaled air of 15 mg / L or greater, or in some examples a moisture concentration of 18 mg / L or greater. In some examples of the technology, it can be advantageous for the moisture concentration to be greater than one of the aforementioned levels to minimise the potential drying of the patient’s airways in use.

[0254] In practical terms, the expired air from a patient’s airways may have a moisture concentration of between approximately 40mg / L and 50mg / L and in examples of the technology, it may be advantageous to maintain this moisture concentration as high as possible, to prevent or otherwise reduce the patient’s airways from drying out, potentially increasing patient comfort and compliance.

[0255] In one form, the device 6000 may be configured to provide a pressure drop of less than 5 cmFhO when measured at an airflow rate of lOOL / minute. For example it may be advantageous for the device 6000 to be configured to provide a pressure drop of less than 3 cmFhO or less than 1 cmHzO when measured at an airflow rate of lOOL / minute. Reducing or otherwise minimising the pressure drop caused by the device 6000 may advantageously improve patient comfort and compliance, and reduce the effort required to breathe through the device 6000.

[0256] In examples of the technology where a device 6000 is provided within a patient interface, the dimensions and thickness of the device 6000 may be adjusted to achieve any one or more of the foregoing moisture retention and flow impedance parameters described herein. For example, when positioned within a patient interface, the device 6000 may be dimensioned to match the internal bore of the connection port 3600. In other examples, the device 6000 may be provided in a spaced relationship relative to the connection port 3600, such as with an air gap between the connection port 3600 and the device of between approximately 1 mm and approximately 10 mm, such as 5 mm. In larger masks, such as full-face masks the air gap between the connection port 3600 and the device 6000 may be between 5 mm and 10 mm, while in nasal interfaces, the air gap between the connection port 3600, and device 6000 may be between 1 mm and 5 mm.

[0257] In examples of the technology, where a plurality of connection ports 3600 are provided, a device 6000 may be configured to sit in the airflow path between each connection port 3600, and the patient’s airways, or alternatively a plurality of devices 6000 may be provided, such as one for each connection port 3600.

[0258] In a full-face mask in which the device 6000 in positioned proximal to, within, or otherwise contacting the connection port 3600, the device may be configured with a width of between approximately 20 mm and 50 mm, a height of between 20 mm and 50 mm, and a thickness of between 2mm and 10mm. For example, the device 6000 may be dimensioned to engage with and / or attach to the connection port 3600.

[0259] In a full-face mask in which the device 6000 is positioned in the plenum chamber in a spaced arrangement from the connection port 3600, the device 6000 may be configured with a width of between 20 mm and 70 mm, a height of between 20 mm and 100 mm and a thickness of between 2 mm and 5 mm.

[0260] In a nasal mask in which the device 6000 in positioned proximal to, within, or otherwise contacting the connection port 3600, the device may be configured with a width of between approximately 10 mm and 25 mm, a height of between 10 mm and 25mm, and a thickness of between 3mm and 15 mm. For example, the device 6000 may be dimensioned to engage with and / or attach to the connection port 3600.

[0261] In a nasal mask in which the device 6000 is positioned in the plenum chamber in a spaced arrangement from the connection port 3600, the device 6000 may be configured with a width of between 20 mm and 50 mm, a height of between 20 mm and 50 mm and a thickness of between 2 mm and 10 mm.

[0262] The device 6000, may have any suitable shape, including square, rectangular, circular, or any other suitable geometry. For example, the device 6000 may be provided with an outer perimeter which is complementary to an inner surface of the patient interface, such that the device engages with and is supported by the inner surfaces of the patient interface.

[0263] In an example of the technology, the device 6000 may have any one or more of a humidification agent concentration of between approximately 7% and approximately 12%, a moisture retention rate of 13 to 20 mg / L, and an impedance which results in a pressure drop at lOOL / min which is less than 1 cmFhO such as between 0.3 cmFhO and 0.7 cmHiO.

[0264] In an example of the technology, the device 6000 may have a substantially circular or rectangular heat and moisture exchanging material, having a diameter, width and / or height of between approximately 24 mm and 28 mm. In examples the heat and moisture exchanging material may have a thickness of between 8 mm and 12 mm such as substantially 10 mm.

[0265] In an example of the technology, the device 6000 may have a substantially circular or rectangular heat and moisture exchanging material, having a diameter, width and / or height of between approximately 8 mm and 15 mm. In examples the heat and moisture exchanging material may have a thickness of between 8 mm and 12 mm such as substantially 10 mm.

[0266] Fig. 11 shows an increase in average absolute humidity when measured in the posterior chamber 6006 of the patient interface 3000 comprising a device 6000 in use.As shown, the absolute humidity was measured in the patient interface 3000 proximal to the entrance of a patient’s airways 1004 in: 1) a patient interface 3000 without the device 6000, 2) a patient interface 3000 comprising the device 6000 comprising a HME material, and 3) a patient interface 3000 comprising the device 6000 in the form of a woven material that is heat non-absorbent or resistant to absorption of heat and moisture non-absorbent or resistant to absorption of moisture. The results show a significantincrease in absolute humidity, with the best result shown for the patient interface comprising the device 6000 in the form of a woven material that is heat non-absorbent or resistant to absorption of heat and moisture non-absorbent or resistant to absorption of moisture.

[0267] Figs. 12A and 12B show a test rig or a model 3900 that was utilised to measure the turbulence of the flow of breathable gas 7000 in a simulated patient interface system with a device 6000 and a simulated patient interface system without a device 6000. The test rig 3900 comprises a simulated entrance 1002 to the patient’s airways, a simulated vent 3400 and a simulated connection port 3600. The volume of the test rig 3900 may also be understood to be defined, at least in part, by simulated forms of the seal-forming structure 3100 and the plenum chamber 3200. In other words, the test rig 3900 may be understood to model the breathing chamber defined, at least in part, by the seal-forming structure 3100 and the plenum chamber 3200 when placed against the patient’s face.

[0268] Figs. 13A to 16B show the results of measuring turbulence or flow in the test rig 3900 using a computational fluid dynamics program. The results show that in the test rig 3900 comprising the device 6000 that the turbulence of the gas may be reduced significantly by the device 6000, when compared to the test rig 3900 without the device 6000. Although Figs. 12A and 12B show the test rig 3900 with the device 6000, it should be understood that the Figs. 13A, 14A, 15A, and 16A depict modelling of flows in the test rig 3900 without the device 6000, while Figs. 13B, 14B, 15B, and 16B show depict modelling of flows in the test rig 3900 with the device 6000.

[0269] Figs. 13A and 13B show velocities of gas flow in the test rig 3900 without and with the device 6000, respectively. In this simulation, the patient's expiratory flow 7002 via the simulated entrance 1002 is zero and there is a flow of breathable gas 7000 entering into the test rig 3900 via the connection port 3600. As can be seen in Fig. 13B, where the test rig 3900 includes the device 6000, turbulence is reduced in the posterior chamber 6006 relative to the anterior chamber 6004.

[0270] Figs. 14A and 14B show velocities of gas flow in the test rig 3900 without and with the device 6000, respectively. In this simulation, the patient’s expiratory flow 7002 via the simulated entrance 1002 is positive, i.e., the patient is exhaling, and there is a flow of breathable gas 7000 entering into the test rig 3900 via the connection port 3600. As can be seen in Fig. 13B, where the test rig 3900 includes the device 6000, turbulence is reduced in the posterior chamber 6006 relative to the anterior chamber 6004.

[0271] Figs. 15A and 15B show streamlines of gas flow in the test rig 3900 without and with the device 6000, respectively. In this simulation, the patient's expiratory flow 7002 via the simulated entrance 1002 is zero and there is a flow of breathable gas 7000 entering into the test rig 3900 via the connection port 3600. As can be seen in Fig. 15B, where the test rig 3900 includes the device 6000, turbulence is reduced in the posterior chamber 6006 relative to the anterior chamber 6004.

[0272] Figs. 16A and 16B show streamlines of gas flow in the test rig 3900 without and with the device 6000, respectively. In this simulation, the patient’s expiratory flow 7002 via the simulated entrance 1002 is positive, i.e., the patient is exhaling, and there is a flow of breathable gas 7000 entering into the test rig 3900 via the connection port 3600. As can be seen in Fig. 16B, where the test rig 3900 includes the device 6000, turbulence is reduced in the posterior chamber 6006 relative to the anterior chamber 6004.5.3.11 Modularity

[0273] 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.

[0274] 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.

[0275] 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. 3B). 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 patient may 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. 3B). 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.

[0276] 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.5.3.11.1 Sleeve

[0277] 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. 17G to 171, 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.

[0278] 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.

[0279] 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.

[0280] 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 elastic material 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.

[0281] 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.).5.3.11.1.1 Conduit Sleeve

[0282] As shown in Fig. 17G, one example of a sleeve is a conduit sleeve 3351, which may be usable with the tubes 3350 described above.

[0283] As shown in Fig. 17G, the conduit sleeve 3351 may include a curved shape that may be similar to the shape of the tubes 3350 shown in Fig. 17C. 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).

[0284] 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.

[0285] As shown in Fig. 17G, 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.

[0286] Some forms of the inferior extension 3354 may include a rigid or semi-rigid 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).

[0287] As shown in Fig. 17G, 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 may be 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 theinferior extension 3354, although the connection member 3356 could alternatively be positioned anywhere along the inferior extension 3354.

[0288] 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. 171-1), 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.5.3.11.1.2 Four-point arm sleeve

[0289] As shown in Fig. 17H, another example of a sleeve is a four-point arm sleeve 3380, which may be usable with the rigidiser arms 3340 described above.

[0290] As shown in Fig. 17H, 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. 17D. 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).

[0291] As shown in Fig. 17H, 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.

[0292] 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).

[0293] As shown in Fig. 17H, 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.

[0294] 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.17K), 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.

[0295] As shown in Fig. 17H, 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 3350.5.3.11.1.3 Two-point arm sleeve

[0296] As shown in Fig. 171, 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.

[0297] 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.

[0298] As shown in Fig. 171, 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.

[0299] As shown in Fig. 171, 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 3350.5.3.11.2 Assembled Patient Interfaces

[0300] As illustrated in Figs. 17J-1 to 17M, 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.5.3.11.2.1 Nose and Mouth Mask Tube Up Configuration

[0301] As illustrated in Fig. 17J-1 and 17J-2, 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.

[0302] 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.

[0303] 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. 17E) of the four-point headgear 3302-1. Alternatively, a different connection form may be used.

[0304] As illustrated in Fig. 17J, 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.

[0305] 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.

[0306] In some examples the device 6000 configured to exchange heat and / or moisture between the air exhaled by the patient and the air inhaled by the patient may be positioned in the one or more headgear tubes 3350, for example a first device 6000 in a first headgear tube 3350 extending on a first side of the patient’s face in use, and a second device 6000 in a second headgear tube 3350 positioned on a second side of the patient’s face in use.

[0307] In another example the device 6000 may be provided in or adjacent to the one or more plenum chamber inlet ports 3254-1. For example, with reference to Fig 17A-2, a first device 6000 may be attached to a first chamber inlet port 3254-1, and a second device 6000 may be attached to the second chamber inlet port 3254-1. In some examples the device 6000 may be releasably attached as described herein.

[0308] In a further example, the device 6000 may be provided at or adjacent to the inlet 3332, for example the device 6000 may be configured to releasably attach to the inlet 3332. By providing a device 6000 which is attached to or otherwise provided in the inlet 3332, the present technology may be provided via a single device 6000, rather than requiring a device in each plenum chamber inlet port 3254-1 or each headgear tube 3350.

[0309] In a further example, shown in Fig 17A-3 and illustrated as part of a system in Fig. 17K the device 6000 may be provided in or adjacent to the vent opening 3402-1 or connection port 3600.

[0310] Alternatively as described herein a device 6000 may be positioned in, or otherwise attached to the plenum chamber 3200.5.3.11.2.2 Nose and Mouth Mask Tube Down Configuration

[0311] As illustrated in Fig. 17K, the patient may wear the cushion 3050- 1 in a tubedown 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.

[0312] 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.

[0313] 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. 17E) of the four-point headgear 3302-1. Alternatively, a different connection form may be used.

[0314] As illustrated in Fig. 17K, 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.

[0315] 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.

[0316] In tube down patient interfaces, such as those shown in Fig. 3 A, 3B, and 17K the device 6000 configured to exchange heat and / or moisture between the air exhaled by the patient and the air inhaled by the patient may be positioned in or otherwise attached to the connection port 3600, such as is shown in Fig. 17A-3. For example, the device 6000 may be configured to releasably attach to the connection port 3600 or vent opening 3402-1.

[0317] In other examples, the device 6000 may be provided in, or otherwise attached to the air circuit 4170. Alternatively, as described herein the device 6000 may be positioned in, or otherwise attached to the plenum chamber 3200.5.3.11.2.3 Nose Mask Tube Up Configuration

[0318] As illustrated in Fig. 17L, 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

[0319] 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.

[0320] As illustrated in Fig. 17L, 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.

[0321] As discussed in relation to patient interfaces 3000 with a nose and mouth tube- up configuration, the device 6000 may be positioned in or otherwise attached to any one or more of: the headgear tubes 3350, plenum chamber inlet ports 3254-1, or the inlet 3332; see for example Figs. 17B-2 and 17B-3.

[0322] Alternatively, as described herein the device 6000 may be positioned in, or otherwise attached to the plenum chamber 3200.5.3.11.2.4 Nose Mask Tube Down Configuration

[0323] As illustrated in Fig. 17M, 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.

[0324] 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 the cushion 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.

[0325] As illustrated in Fig. 17M, 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.

[0326] In tube down patient interfaces, such as those shown in Fig. 17M, the device 6000 configured to exchange heat and / or moisture between the air exhaled by the patient and the air inhaled by the patient may be positioned in or otherwise attached to the connection port 3600 as shown in Fig. 17B-3. For example, the device 6000 may be configured to releasably attach to the connection port 3600.

[0327] In other examples, the device 6000 may be provided in, or otherwise attached to the air circuit 4170. Alternatively, as described herein the device 6000 may be positioned in, or otherwise attached to the plenum chamber 3200.5.3.11.2.5 Modularity of Elements

[0328] Fig. 17P 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. 170 shows a portion of air circuit 4170 that may interface with the patient interface, while Fig. 17N shows a vent 3404 that may interchangeably replace the air circuit shown in Fig. 170, depending on the style of the patient interface.5.4 RPT DEVICE

[0329] An RPT device 4000 in accordance with one aspect of the present technology comprises mechanical and pneumatic components 4100, electrical components 4200 and is configured to execute one or more algorithms 4300. 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.

[0330] The pneumatic path of the RPT device 4000 may comprise one or more air path items, e.g., an inlet air filter 4112, an inlet muffler 4122, a pressure generator 4140 capable of supplying air at positive pressure (e.g., a blower 4142), an outlet muffler 4124 and one or more transducers 4270, such as pressure sensors 4272 and flow rate sensors 4274.

[0331] 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.

[0332] The RPT device 4000 may have an electrical power supply 4210, one or more input devices 4220, a central controller 4230, a therapy device controller 4240, a pressure generator 4140, one or more protection circuits 4250, memory 4260, transducers 4270, data communication interface 4280 and one or more output devices 4290. Electrical components 4200 may be mounted on a single Printed Circuit Board Assembly (PCBA) 4202. In an alternative form, the RPT device 4000 may include more than one PCBA 4202.5.4.1 RPT device mechanical & pneumatic components

[0333] 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)

[0334] 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.

[0335] 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. See Fig.

[0336] 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 See Fig. or 3800.5.4.1.2 Muffler(s)

[0337] An RPT device in accordance with one form of the present technology may include a muffler 4120, or a plurality of mufflers 4120.

[0338] 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. See Fig.

[0339] 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

[0340] 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 a positive 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.

[0341] The pressure generator 4140 may be under the control of the therapy device controller 4240.

[0342] 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)

[0343] Transducers may be internal of the RPT device, or external of the RPT device. External transducers may be located for example on or form part of the air circuit, e.g., the patient interface. External transducers may be in the form of non-contact sensors such as a Doppler radar movement sensor that transmit or transfer data to the RPT device.

[0344] 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.

[0345] In one form of the present technology, one or more transducers 4270 may be located proximate to the patient interface 3000 or 3800.

[0346] In one form, a signal from a transducer 4270 may be filtered, such as by low- pass, high-pass or band-pass filtering.5.4. 1.4. 1 Flow rate sensor

[0347] A flow rate sensor 4274 in accordance with the present technology may be based on a differential pressure transducer, for example, an SDP600 Series differential pressure transducer from SENSIRION.

[0348] In one form, a signal generated by the flow rate sensor 4274 andi epresenting a flow rate such as a total flow rate Qi from the flow rate transducer 4274 is received by the central controller 4230.5.4.1.4.2 Pressure sensor

[0349] A pressure sensor 4272 in accordance with the present technology is located in fluid communication with the pneumatic path. An example of a suitable pressure sensor is a transducer from the HONEYWELL ASDX series. An alternative suitable pressure sensor is a transducer from the NPA Series from GENERAL ELECTRIC.

[0350] In one form, a signal generated by the pressure sensor 4272 and representing a pressure is received by the central controller 4230.5.4.1.4.3 Motor speed transducer

[0351] In one form of the present technology a motor speed transducer 4276 is used to determine a rotational velocity of the motor 4144 and / or the blower 4142. A motor speed signal from the motor speed transducer 4276 may be provided to the therapy device controller 4240. The motor speed transducer 4276 may, for example, be a speed sensor, such as a Hall effect sensor.5.4.1.5 Anti-spill back valve

[0352] As shown in Fig. 4B, one form of the present technology, an anti-spill back valve 4160 is located between the humidifier 5000 and the pneumatic block 4020. The anti-spill back valve is constructed and arranged to reduce the risk that water will flow upstream from the humidifier 5000, for example to the motor 4144.5.4.1.6 Air circuit

[0353] An air circuit 4170 in accordance with an aspect of the present technology is a conduit or a tube constructed and arranged in use to allow a flow of air to travel between two components such as the pneumatic block 4020 and the patient interface 3000.

[0354] In particular, the air circuit 4170 may be in fluid connection with the outlet of the pneumatic block and the patient interface. The air circuit may be referred to as an air delivery tube. In some cases there may be separate limbs of the circuit for inhalation and exhalation. In other cases a single limb is used.

[0355] 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 such as a central controller 4230 or a humidifier controller 5250. One example of an air circuit 4170 comprising a heated wire circuit is described in United States Patent Application No.US / 2011 / 0023874, which is incorporated herewithin in its entirety by reference.5.4.1.7 Oxygen delivery

[0356] In one form of the present technology, supplemental oxygen 4180 is delivered to one or more points in the pneumatic path, such as upstream of the pneumatic block 4020, to the air circuit 4170 and / or to the patient interface 3000.5.4.2 RPT device electrical components5.4.2.1 Power supply

[0357] A power supply 4210 may be located internal or external of the external housing 4010 of the RPT device 4000.

[0358] In one form of the present technology power supply 4210 provides electrical power to the RPT device 4000 only. In another form of the present technology, power supply 4210 provides electrical power to both RPT device 4000 and humidifier 5000.5.4.2.2 Input devices

[0359] In one form of the present technology, an RPT device 4000 includes one or more input devices 4220 in the form of buttons, switches or dials to allow a person to interact with the device. The buttons, switches or dials may be physical devices, or software devices accessible via a touch screen. The buttons, switches or dials may, in one form, be physically connected to the external housing 4010, or may, in another form, be in wireless communication with a receiver that is in electrical connection to the central controller 4230.

[0360] In one form, the input device 4220 may be constructed and arranged to allow a person to select a value and / or a menu option.5.4.2.3 Central controller

[0361] In one form of the present technology, the central controller 4230 is one or a plurality of processors suitable to control an RPT device 4000.

[0362] Suitable processors may include an x86 INTEL processor, a processor based on ARM® Cortex®-M processor from ARM Holdings such as an STM32 series microcontroller from ST MICROELECTRONIC. In certain alternative forms of the present technology, a 32-bit RISC CPU, such as an STR9 series microcontroller from ST MICROELECTRONICS or a 16-bit RISC CPU such as a processor from the MSP430 family of microcontrollers, manufactured by TEXAS INSTRUMENTS may also be suitable.

[0363] In one form of the present technology, the central controller 4230 is a dedicated electronic circuit.

[0364] In one form, the central controller 4230 is an application- specific integrated circuit. In another form, the central controller 4230 comprises discrete electronic components.

[0365] The central controller 4230 may be configured to receive input signal(s) from one or more transducers 4270, and one or more input devices 4220.

[0366] The central controller 4230 may be configured to provide output signal(s) to one or more of an output device 4290, a pressure generator 4140, a therapy devicecontroller 4240, a data communication interface 4280, and / or the humidifier controller 5250.

[0367] In some forms of the present technology, the central controller 4230 is configured to implement the one or more methodologies described herein, such as the one or more algorithms 4300 which may be implemented with processor-control instructions, expressed as computer programs stored in a non-transitory computer readable storage medium, such as memory 4260. In some forms of the present technology, the central controller 4230 may be integrated with an RPT device 4000. However, in some forms of the present technology, some methodologies may be performed by a remotely located device. For example, the remotely located device may determine control settings for a ventilator or detect respiratory related events by analysis of stored data such as from any of the sensors described herein.5.4.2.4 Clock

[0368] The RPT device 4000 may include a clock 4232 that is connected to the central controller 4230.5.4.2.5 Therapy device controller

[0369] In one form of the present technology, therapy device controller 4240 is a control module 4330 that forms part of the algorithms 4300 executed by the central controller 4230.

[0370] In one form of the present technology, therapy device controller 4240 is a dedicated motor control integrated circuit. For example, in one form a MC33035 brushless DC motor controller, manufactured by ONSEMI is used.5.4.2.6 Protection circuits

[0371] The one or more protection circuits 4250 in accordance with the present technology may comprise an electrical protection circuit, a temperature and / or pressure safety circuit.5.4.2.7 Memory

[0372] In accordance with one form of the present technology the RPT device 4000 includes memory 4260, e.g., non-volatile memory. In some forms, memory 4260 may include battery powered static RAM. In some forms, memory 4260 may include volatile RAM.

[0373] Memory 4260 may be located on the PCBA 4202. Memory 4260 may be in the form of EEPROM, or NAND flash.

[0374] Additionally or alternatively, RPT device 4000 includes a removable form of memory 4260, for example a memory card made in accordance with the Secure Digital (SD) standard.

[0375] In one form of the present technology, the memory 4260 acts as a non- transitory computer readable storage medium on which is stored computer program instructions expressing the one or more methodologies described herein, such as the one or more algorithms 4300.5.4.2.8 Data communication systems

[0376] In one form of the present technology, a data communication interface 4280 is provided, and is connected to the central controller 4230 (see e.g., Fig. 4C). Data communication interface 4280 may be connectable to a remote external communication network 4282 and / or a local external communication network 4284. The remote external communication network 4282 may be connectable to a remote external device 4286. The local external communication network 4284 may be connectable to a local external device 4288.

[0377] In one form, data communication interface 4280 is part of the central controller 4230. In another form, data communication interface 4280 is separate from the central controller 4230, and may comprise an integrated circuit or a processor.

[0378] In one form, remote external communication network 4282 is the Internet. The data communication interface 4280 may use wired communication (e.g. via Ethernet, or optical fibre) or a wireless protocol (e.g. CDMA, GSM, LTE) to connect to the Internet.

[0379] In one form, local external communication network 4284 utilises one or more communication standards, such as Bluetooth, or a consumer infrared protocol.

[0380] In one form, remote external device 4286 is one or more computers, for example a cluster of networked computers. In one form, remote external device 4286 may be virtual computers, rather than physical computers. In either case, such a remote external device 4286 may be accessible to an appropriately authorised person such as a clinician.

[0381] The local external device 4288 may be a personal computer, mobile phone, tablet or remote control.5.4.2.9 Output devices including optional display, alarms

[0382] An output device 4290 in accordance with the present technology may take the form of one or more of a visual, audio and haptic unit. A visual display may be a Liquid Crystal Display (LCD) or Light Emitting Diode (LED) display.5.4.2.9.1 Display driver

[0383] A display driver 4292 receives as an input the characters, symbols, or images intended for display on the display 4294, and converts them to commands that cause the display 4294 to display those characters, symbols, or images.5.4.2.9.2 Display

[0384] A display 4294 is configured to visually display characters, symbols, or images in response to commands received from the display driver 4292. For example, the display 4294 may be an eight-segment display, in which case the display driver 4292 converts each character or symbol, such as the figure “0”, to eight logical signals indicating whether the eight respective segments are to be activated to display a particular character or symbol.5.5 HUMIDIFIER5.5.1 Humidifier overview

[0385] 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.

[0386] 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. 5 A 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 5240.5.5.2 Humidifier components5.5.2.1 Water reservoir

[0387] According to one arrangement, the humidifier 5000 may comprise a water reservoir 5110 configured to hold, or retain, a volume of liquid (e.g. water) to be evaporated for humidification of the flow of air. The water reservoir 5110 may be configured to hold a predetermined maximum volume of water in order to provide adequate humidification for at least the duration of a respiratory therapy session, such as one evening of sleep. Typically, the reservoir 5110 is configured to hold several hundred millilitres of water, e.g. 300 millilitres (ml), 325 ml, 350 ml or 400 ml. In other forms, the humidifier 5000 may be configured to receive a supply of water from an external water source such as a building’s water supply system.

[0388] According to one aspect, the water reservoir 5110 is configured to add humidity to a flow of air from the RPT device 4000 as the flow of air travels therethrough. In one form, the water reservoir 5110 may be configured to encourage the flow of air to travel in a tortuous path through the reservoir 5110 while in contact with the volume of water therein.

[0389] According to one form, the reservoir 5110 may be removable from the humidifier 5000, for example in a lateral direction as shown in Fig. 5 A and Fig. 5B.

[0390] The reservoir 5110 may also be configured to discourage egress of liquid therefrom, such as when the reservoir 5110 is displaced and / or rotated from its normal, working orientation, such as through any apertures and / or in between its subcomponents. As the flow of air to be humidified by the humidifier 5000 is typically pressurised, the reservoir 5110 may also be configured to prevent losses in pneumatic pressure through leak and / or flow impedance.5.5.2.2 Conductive portion

[0391] According to one arrangement, the reservoir 5110 comprises a conductive portion 5120 configured to allow efficient transfer of heat from the heating element 5240 to the volume of liquid in the reservoir 5110. In one form, the conductive portion 5120 may be arranged as a plate, although other shapes may also be suitable. All or a part of the conductive portion 5120 may be made of a thermally conductive material such as aluminium (e.g. approximately 2 mm thick, such as 1 mm, 1.5 mm, 2.5 mm or 3 mm),another heat conducting metal or some plastics. In some cases, suitable heat conductivity may be achieved with less conductive materials of suitable geometry.5.5.2.3 Humidifier reservoir dock

[0392] In one form, the humidifier 5000 may comprise a humidifier reservoir dock 5130 (as shown in Fig. 5B) configured to receive the humidifier reservoir 5110. In some arrangements, the humidifier reservoir dock 5130 may comprise a locking feature such as a locking lever 5135 configured to retain the reservoir 5110 in the humidificr rcservoir dock 5130.5.5.2.4 Water level indicator

[0393] The humidifier reservoir 5110 may comprise a water level indicator 5150 as shown in Fig. 5A-5B. In some forms, the water level indicator 5150 may provide one or more indications to a user such as the patient 1000 or a care giver regarding a quantity of the volume of water in the humidifier reservoir 5110. The one or more indications provided by the water level indicator 5150 may include an indication of a maximum, predetermined volume of water, any portions thereof, such as 25%, 50% or 75% or volumes such as 200 ml, 300 ml or 400ml.5.5.3 Humidifier Electrical & thermal components

[0394] The humidifier 5000 may comprise a number of electrical and / or thermal components such as those listed below.5.5.3.1 Humidifier transducer(s)

[0395] The humidifier 5000 may comprise one or more humidifier transducers (sensors) 5210 instead of, or in addition to, transducers 4270 described above. Humidifier transducers 5210 may include one or more of an air pressure sensor 5212, an air flow rate transducer 5214, a temperature sensor 5216, or a humidity sensor 5218 as shown in Fig. 5C. A humidifier transducer 5210 may produce one or more output signals which may be communicated to a controller such as the central controller 4230 and / or the humidifier controller 5250. In some forms, a humidifier transducer may be located externally to the humidifier 5000 (such as in the air circuit 4170) while communicating the output signal to the controller.5.5.3.1.1 Pressure transducer

[0396] One or more pressure transducers 5212 may be provided to the humidifier 5000 in addition to, or instead of, a pressure sensor 4272 provided in the RPT device 4000.5.5.3.1.2 Flow rate transducer

[0397] One or more flow rate transducers 5214 may be provided to the humidifier 5000 in addition to, or instead of, a flow rate sensor 4274 provided in the RPT device 4000.5.5.3.1.3 Temperature transducer

[0398] The humidifier 5000 may comprise one or more temperature transducers 5216. The one or more temperature transducers 5216 may be configured to measure one or more temperatures such as of the heating element 5240 and / or of the flow of air downstream of the humidifier outlet 5004. In some forms, the humidifier 5000 may further comprise a temperature sensor 5216 to detect the temperature of the ambient air.5.5.3.1.4 Humidity transducer

[0399] In one form, the humidifier 5000 may comprise one or more humidity sensors 5218 to detect a humidity of a gas, such as the ambient air. The humidity sensor 5218 may be placed towards the humidifier outlet 5004 in some forms to measure a humidity of the gas delivered from the humidifier 5000. The humidity sensor may be an absolute humidity sensor or a relative humidity sensor.5.5.3.2 Heating element

[0400] A heating element 5240 may be provided to the humidifier 5000 in some cases to provide a heat input to one or more of the volume of water in the humidifier reservoir 5110 and / or to the flow of air. The heating element 5240 may comprise a heat generating component such as an electrically resistive heating track. One suitable example of a heating element 5240 is a layered heating element such as one described in the PCT Patent Application Publication No. WO 2012 / 171072, which is incorporated herewith by reference in its entirety.

[0401] In some forms, the heating element 5240 may be provided in the humidifier base 5006 where heat may be provided to the humidifier reservoir 5110 primarily by conduction as shown in Fig. 5B.5.5.3.3 Humidifier controller

[0402] According to one arrangement of the present technology, a humidifier 5000 may comprise a humidifier controller 5250 as shown in Fig. 5C. In one form, the humidifier controller 5250 may be a part of the central controller 4230. In another form, the humidifier controller 5250 may be a separate controller, which may be in communication with the central controller 4230.

[0403] In one form, the humidifier controller 5250 may receive as inputs measures of properties (such as temperature, humidity, pressure and / or flow rate), for example of the flow of air, the water in the reservoir 5110 and / or the humidifier 5000. The humidifier controller 5250 may also be configured to execute or implement humidifier algorithms and / or deliver one or more output signals.

[0404] As shown in Fig. 5C, the humidifier controller 5250 may comprise one or more controllers, such as a central humidifier controller 5251, a heated air circuit controller 5254 configured to control the temperature of a heated air circuit 4171 and / or a heating element controller 5252 configured to control the temperature of a heating element 5240.5.6 BREATHING WAVEFORMS

[0405] 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, Ttot, 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%.5.7 GLOSSARY

[0406] 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.5.7.1 General

[0407] 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.

[0408] 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.

[0409] 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.

[0410] In another example, ambient pressure may be the pressure immediately surrounding or external to the body.

[0411] 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.

[0412] Continuous Positive Airway Pressure (CPAP) therapy: CPAP therapy will be taken to mean the application of a supply of air to an entrance to the airways at a pressure that is continuously positive with respect to atmosphere. The pressure may be 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.

[0413] Patient: A person, whether or not they are suffering from a respiratory disease.

[0414] 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.5.7.2 Aspects of the respiratory cycle

[0415] 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.

[0416] Breathing rate: The rate of spontaneous respiration of a patient, usually measured in breaths per minute.

[0417] Duty cycle: The ratio of inhalation time, Ti to total breath time, Ttot.

[0418] Effort (breathing): Breathing effort will be said to be the work done by a spontaneously breathing person attempting to breathe.

[0419] Expiratory portion of a breathing cycle: The period from the start of expiratory flow to the start of inspiratory flow.

[0420] 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.

[0421] 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.

[0422] Hypopnea: Preferably, a hypopnea will be 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 inbreathing 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.

[0423] Hyperpnec . An increase in flow to a level higher than normal flow rate.

[0424] 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.

[0425] 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).

[0426] Positive End-Expiratory Pressure (PEEP)'. The pressure above atmosphere in the lungs that exists at the end of expiration.

[0427] Peak flow rate ( Qpeak): The maximum value of flow rate during the inspiratory portion of the respiratory flow waveform.

[0428] Respiratory flow rate, airflow rate, patient airflow rate, respiratory airflow rate (Qr): These synonymous terms may be understood to refer to the RPT device’s estimate of respiratory airflow rate, as opposed to “true respiratory flow” or “true respiratory airflow”, which is the actual respiratory flow rate experienced by the patient, usually expressed in litres per minute.

[0429] Tidal volume (Vt): The volume of air inhaled or exhaled during normal breathing, when extra effort is not applied.

[0430] (inhalation) Time (Ti): The duration of the inspiratory portion of the respiratory flow rate waveform.

[0431] (exhalation) Time (Te): The duration of the expiratory portion of the respiratory flow rate waveform.

[0432] (total) Time (Ttot)'. The total duration between the start of the inspiratory portion of one respiratory flow rate waveform and the start of the inspiratory portion of the following respiratory flow rate waveform.

[0433] Typical recent ventilation'. The value of ventilation around which recent values over some predetermined timescale tend to cluster, that is, a measure of the central tendency of the recent values of ventilation.

[0434] 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 level of flow increases only slightly or may even decrease as the pressure difference across the upper airway increases (Starling resistor behaviour).

[0435] Ventilation (Vent): A measure of the total amount of gas being exchanged by the patient’s respiratory system. Measures of ventilation may include one or both of inspiratory and expiratory flow, per unit time. When expressed as a volume per minute, this quantity is often referred to as “minute ventilation”. Minute ventilation is sometimes given simply as a volume, understood to be the volume per minute.5.7.3 RPT device parameters

[0436] Flow rate: The instantaneous volume (or mass) of air delivered per unit time. While flow rate and ventilation have the same dimensions of volume or mass per unit time, flow rate is measured over a much shorter period of time. 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. Where it is referred to as a signed quantity, 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. Flow rate will be given the symbol Q. ‘Flow rate’ is sometimes shortened to simply ‘flow’ Total flow rate, Qt, is the flow rate of air leaving the RPT device. Vent flow rate, Qv, is the flow rate of air leaving a vent to allow washout of exhaled gases. Leak flow rate, QI, is the flow rate of leak from a patient interface system. Respiratory flow rate, Qr, is the flow rate of air that is received into the patient's respiratory system.

[0437] 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.

[0438] 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 andthe 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.

[0439] 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.

[0440] 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 in the patient interface.

[0441] Pressure: Force per unit area. Pressure may be measured in a range of units, including cmthO, g-f / cm2, hectopascal. 1 cmlFO is equal to 1 g-f / cm2and is approximately 0.98 hectopascal. In this specification, unless otherwise stated, pressure is given in units of cmFhO. The pressure in the patient interface is given the symbol Pm, while the treatment pressure, which represents a target value to be achieved by the mask pressure Pm at the current instant of time, is given the symbol Pt.

[0442] Sound Power: The energy per unit time carried by a sound wave. The sound power is proportional to the square of sound pressure multiplied by the area of the wavefront. Sound power is usually given in decibels SWL, that is, decibels relative to a reference power, normally taken as 10’12watt.

[0443] Sound Pressure: The local deviation from ambient pressure at a given time instant as a result of a sound wave travelling through a medium. Sound pressure is usually given in decibels SPL, that is, decibels relative to a reference pressure, normally taken as 20 x 10’6Pascal (Pa), considered the threshold of human hearing.5.7.4 Terms for ventilators

[0444] 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.

[0445] 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.

[0446] 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 inspiratoryportion of the breathing cycle, the ventilator is said to be cycled to stop delivering the breath.

[0447] EPAP: a base pressure, to which a pressure varying within the breath is added to produce the desired mask pressure which the ventilator will attempt to achieve at a given time.

[0448] IPAP: desired mask pressure which the ventilator will attempt to achieve during the inspiratory portion of the breath.

[0449] 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 minimum value during expiration (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.

[0450] 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.

[0451] 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.

[0452] Swing: Equivalent term to pressure support.

[0453] Triggered: When a ventilator delivers a breath of air to a spontaneously breathing patient, it is said to be triggered to do so at the initiation of the respiratory portion of the breathing cycle by the patient's efforts.

[0454] Typical recent ventilation: The typical recent ventilation Vtyp is the value around which recent measures of ventilation over some predetermined timescale tend to cluster. For example, a measure of the central tendency of the measures of ventilation over recent history may be a suitable value of a typical recent ventilation.

[0455] Ventilator: A mechanical device that provides pressure support to a patient to perform some or all of the work of breathing.5.7.5 Anatomy of the face

[0456] Ala: the external outer wall or "wing" of each nostril (plural: alar)

[0457] Alare: The most lateral point on the nasal ala.

[0458] 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.

[0459] Auricle: The whole external visible part of the ear.

[0460] (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.

[0461] (nose) Cartilaginous framework: The cartilaginous framework of the nose comprises the septal, lateral, major and minor cartilages.

[0462] Columella: the strip of skin that separates the nares and which runs from the pronasale to the upper lip.

[0463] Columella angle: The angle between the line drawn through the midpoint of the nostril aperture and a line drawn perpendicular to the Frankfurt horizontal while intersecting subnasale.

[0464] 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.

[0465] Glabella: Located on the soft tissue, the most prominent point in the midsagittal plane of the forehead.

[0466] 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.

[0467] 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.

[0468] 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.

[0469] Naso-labial sulcus or Naso-labial fold: The skin fold or groove that runs from each side of the nose to the corners of the mouth, separating the cheeks from the upper lip.

[0470] Naso-labial angle: The angle between the columella and the upper lip, while intersecting subnasale.

[0471] Otobasion inferior: The lowest point of attachment of the auricle to the skin of the face.

[0472] Otobasion superior: The highest point of attachment of the auricle to the skin of the face.

[0473] 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.

[0474] Philtrum: the midline groove that runs from lower border of the nasal septum to the top of the lip in the upper lip region.

[0475] Pogonion: Located on the soft tissue, the most anterior midpoint of the chin.

[0476] Ridge (nasal): The nasal ridge is the midline prominence of the nose, extending from the Sellion to the Pronasale.

[0477] Sagittal plane: A vertical plane that passes from anterior (front) to posterior(rear) dividing the body into right and left halves.

[0478] Sellion: Located on the soft tissue, the most concave point overlying the area of the frontonasal suture.

[0479] Septal cartilage (nasal): The nasal septal cartilage forms part of the septum and divides the front part of the nasal cavity.

[0480] Subalare: The point at the lower margin of the alar base, where the alar base joins with the skin of the superior (upper) lip.

[0481] Subnasal point: Located on the soft tissue, the point at which the columella merges with the upper lip in the midsagittal plane.

[0482] Supramentale: The point of greatest concavity in the midline of the lower lip between labrale inferius and soft tissue pogonion5.7.6 Anatomy of the skull

[0483] Frontal bone: The frontal bone includes a large vertical portion, the squama frontalis, corresponding to the region known as the forehead.

[0484] Mandible: The mandible forms the lower jaw. The mental protuberance is the bony protuberance of the jaw that forms the chin.

[0485] 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.

[0486] 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.

[0487] 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.

[0488] Occipital hone. The occipital bone is situated at the back and lower part of the cranium. It includes an oval aperture, t e foramen magnum, through which the cranial cavity communicates with the vertebral canal. The curved plate behind the foramen magnum is the squama occipitalis.

[0489] Orbit'. The bony cavity in the skull to contain the eyeball.

[0490] Parietal bones'. The parietal bones are the bones that, when joined together, form the roof and sides of the cranium.

[0491] 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.

[0492] 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.5.7.7 Anatomy of the respiratory system

[0493] 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.

[0494] Larynx: The larynx, or voice box houses the vocal folds and connects the inferior part of the pharynx (hypopharynx) with the trachea.

[0495] 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.

[0496] 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.

[0497] 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).5.7.8 Materials

[0498] 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.

[0499] Polycarbonate-, a typically transparent thermoplastic polymer of Bisphenol-A Carbonate.5.7.9 Aspects of a patient interface

[0500] 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.

[0501] Elbow: A conduit that directs an axis of flow of air to change direction through an angle. In one form, the angle may be approximately 90 degrees. In another form, the angle may be less than 90 degrees. The conduit may have an approximately circular cross-section. In another form the conduit 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.

[0502] 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.

[0503] Headgear: Headgear will be taken to mean a form of positioning and stabilizing structure designed for use on a head. Preferably the headgear comprises a collection of one or more struts, ties and stiffeners configured to locate and retain a patient interface in position on a patient’s face for delivery of respiratory therapy. Some ties are formed of a soft, flexible, elastic material such as a laminated composite of foam and fabric.

[0504] 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.

[0505] Plenum chamber: a mask plenum chamber will be taken to mean a portion of a patient interface having walls 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.

[0506] Seal: The noun form ("a seal") will be taken to mean a structure or barrier that intentionally resists the flow of air through the interface of two surfaces. The verb form ("to seal") will be taken to mean to resist a flow of air.

[0507] 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.

[0508] 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.

[0509] 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.

[0510] 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.

[0511] Tie: A tie will be taken to be a structural component designed to resist tension.

[0512] Vent: (noun) the structure that allows an intentional flow of air from an interior of the mask, or conduit to ambient air, e.g. to allow washout of exhaled gases.5.7.10 Terms used in relation to patient interface

[0513] Curvature (of a surface): A region of a surface having a saddle shape, which curves up in one direction and curves down in a different direction, will be said to have a negative curvature. A region of a surface having a dome shape, which curves the same way in two principal directions, will be said to have a positive curvature. A flat surface will be taken to have zero curvature.

[0514] Floppy: A quality of a material, structure or composite that is one or more of:• Readily conforming to finger pressure.• Unable to retain its shape when caused to support its own weight.• Not rigid.• Able to be stretched or bent elastically with little effort.

[0515] The quality of being floppy may have an associated direction, hence a particular material, structure or composite may be floppy in a first direction, but stiff or rigid in a second direction, for example a second direction that is orthogonal to the first direction.

[0516] Resilient; Able to deform substantially elastically, and to release substantially all of the energy upon unloading, within a relatively short period of time such as 1 second.

[0517] Rigid; Not readily deforming to finger pressure, and / or the tensions or loads typically encountered when setting up and maintaining a patient interface in sealing relationship with an entrance to a patient's airways.

[0518] Semi-rigid; means being sufficiently rigid to not substantially distort under the effects of mechanical forces typically applied during respiratory pressure therapy.5.8 OTHER REMARKS

[0519] A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in Patent Office patent files or records, but otherwise reserves all copyright rights whatsoever.

[0520] 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.

[0521] 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.

[0522] Furthermore, “approximately”, “substantially”, “about”, or any similar term used herein means + / - 5-10% of the recited value.

[0523] 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.

[0524] 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.

[0525] 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.

[0526] 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.

[0527] 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.

[0528] 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 foundthroughout the disclosure or the claims. The subject headings should not be used in construing the scope of the claims or the claim limitations.

[0529] 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.

[0530] 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.REFERENCE SIGNS LIST

Claims

6 CLAIMS1. A patient interface for sealed delivery of a flow of air at a continuously positive pressure with respect to ambient air pressure to an entrance to the patient’s airways including at least an entrance of a patient’s nares, wherein the patient interface is configured to maintain a therapy pressure in a range of about 4 cinfbO to about 30 cmHiO above ambient air pressure in use, throughout the patient’s respiratory cycle, while the patient is sleeping, to ameliorate sleep disordered breathing, said patient interface comprising: a seal-forming structure to form a pneumatic seal with the entrance to the patient’s airways; a positioning and stabilising structure to maintain the seal-forming structure in sealing contact with an area surrounding the entrance to the patient’s airways while maintaining a therapeutic pressure at the entrance to the patient’s airways; a plenum chamber pressurised at a pressure above ambient pressure in use; a connection port for the delivery of the flow of breathable gas into the patient interface; and a device positioned along a flow path of breathable gas to physically interfere with the flow; wherein the device is configured to exchange heat and / or moisture between the air exhaled by the patient and the air inhaled by the patient in order to maintain the humidity level of the inhaled air to 10 mg / L or greater.

2. The patient interface of claim 1 , wherein the device is provided with a plurality of apertures, configured to provide an impedance which results in a pressure drop of less than 5 cm of H2O, when measured at a flow rate of 100 litres per minute.

3. The patient interface of claim 2, wherein the impedance results in a pressure drop of less than 2 cm of H2O, when measured at a flow rate of 100 litres per minute.

4. The patient interface of claim 2 or 3, wherein the plurality of apertures comprise a first set of apertures having a first size, and a second set of apertures having a second size, wherein the second size is greater than the second size.

5. The patient interface of any one of claims 2 to 4, wherein at least one of the plurality of apertures comprises an inner surface profile configured to direct the flow of expiratory gas towards a vent for CO2 washout.

6. The patient interface of any one of claims 1 to 5, wherein the device comprises a material from any one of the group consisting of: synthetic materials, thermoplastic elastomers or hydrophobic polymers.

7. The patient interface of any one of claims 1 to 6, wherein the device comprises a mesh structure.

8. The patient interface of claim 6 or 7, wherein the device comprises a foam having between approximately 30 and 150 pores per inch inclusive.

9. The patient interface of any one of claims 6 to 8, wherein the device comprises an open-celled polyurethane foam.

10. The patient interface of any one of claims 1 to 9, wherein the device has a predetermined thickness selected to reduce a flow impedance of the flow breathable gas wherein the predetermined thickness of the device is in the range of 2 mm to 10 mm.

11. The patient interface of claim 10, wherein the predetermined thickness of the device is in the range of 3 mm to 7 mm.

12. The patient interface of claim 10 or 11, wherein the predetermined thickness of the device is substantially 5mm.

13. The patient interface of any one of claims 1 to 12, wherein the device is configured to fit within the plenum chamber of the patient interface.

14. The patient interface of claim 13, wherein the device is positioned within the plenum chamber such that the plenum chamber is divided into a first anterior chamber and a second posterior chamber, the second posterior chamber being proximal to the entrance of the patient’s airways relative to the first anterior chamber.

15. The patient interface of claim 13 or 14, wherein the device physically interferes with a flow of expiratory gas to increase the humidity in the second posterior chamber to a humidity level of 15 mg / L or greater.

16. The patient interface of any one of claims 13 to 15, wherein the device physically interferes with the flow of expiratory gas by decelerating the flow of expiratory gas to the first anterior chamber for redelivery to the entrance of the patient’s airways.

17. The patient interface of any one of claims 1 to 12, further comprising an elbow in fluid communication with the connection port and wherein the device is positioned within or configured to attach to the elbow.

18. The patient interface of any one of claims 1 to 12, further comprising an air delivery conduit for delivering the flow of breathable gas to the patient interface, theair delivery conduit in fluid communication with the connection port and wherein the device is positioned within, or configured to attach to the conduit.

19. The patient interface of any one of claims 1 to 12, wherein the device is positioned in, or configured to attach to the connection port.

20. The patient interface of any one of claims 1 to 12, further comprising a gas washout vent configured to allow a flow of patient exhaled CO2 to an exterior of the patient interface to minimise rebreathing of exhaled CO2 by the patient.

21. The patient interface of claim 20, wherein the device is positioned in a flow path of the flow of breathable gas between the vent and the entrance of the patient’s airways, when in use.

22. The patient interface of any one of the preceding claims, wherein the humidity level of the inhaled air is 18 mg / L or greater.

23. The patient interface of any one of the preceding claims, wherein the positioning and stabilising structure comprises one or more headgear tubes.

24. The patient interface of claim 23 when dependent on any one of claims 1 to 12, wherein the device is provided in the one or more headgear tubes.

25. The patient interface of claim 23 when dependent on any one of claims 1 to 12, wherein the headgear tubes are connected to an inlet, and the device is provided in or configured to attach to the inlet.

26. The patient interface of any one of claims 1 to 12, further comprising one or more plenum chamber inlet ports, wherein the device is provided in or configured to attach to the one or more plenum chamber inlet ports.

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