humidifiers

Abstract

A humidifier for a respiratory therapy apparatus is described. The humidifier comprises an air passage for a gas to be humidified, the air passage having an inlet and outlet. A humidifier reservoir contains a volume of water. A nozzle has an internal passage, wherein an inlet of the nozzle is in fluid communication with the humidifier reservoir, and an outlet of the nozzle is within the air passage. The nozzle comprises a transducer. The transducer is configured to change a volume of the internal passage of the nozzle, to thereby eject a water droplet from the nozzle outlet. A patient interface which includes a nozzle is also described.

Description

HUMIDIFIERS1 CROSS REFERENCE TO RELATED CASES

[0001] The present application claims priority to Australian Provisional Patent Application No. 2024902151, filed on 12 July 2024, the contents of which is included herein by reference in its entirety.2 BACKGROUND OF THE TECHNOLOGY2.1 FIELD OF THE TECHNOLOGY

[0002] The present technology relates to one or more of the screening, diagnosis, monitoring, treatment, prevention and amelioration of respiratory-related disorders. The present technology also relates to medical devices or apparatus, and their use.2.2 DESCRIPTION OF THE RELATED ART2.2.1 Human Respiratory System and its Disorders

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

[0004] The airways include a series of branching tubes, which become narrower, shorter and more numerous as they penetrate deeper into the lung. The prime function of the lung is gas exchange, allowing oxygen to move from the inhaled air into the venous blood and carbon dioxide to move in the opposite direction. The trachea divides into right and left main bronchi, which further divide eventually into terminal bronchioles. The bronchi make up the conducting airways, and do not take part in gas exchange. Further divisions of the airways lead to the respiratory bronchioles, and eventually to the alveoli. The alveolated region of the lung is where the gas exchange takes place, and is referred to as the respiratory zone. See “ Respiratory Physiology”, by John B. West, Lippincott Williams & Wilkins, 9th edition published 2012.

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

[0006] Examples of respiratory disorders include Obstructive Sleep Apnea (OSA), Cheyne-Stokes Respiration (CSR), respiratory insufficiency, Obesity Hypoventilation Syndrome (OHS), Chronic Obstructive Pulmonary Disease (COPD), Neuromuscular Disease (NMD) and Chest wall disorders.2.2.2 Therapies

[0007] Various respiratory therapies, such as Continuous Positive Airway Pressure (CPAP) therapy, Non-invasive ventilation (NIV), Invasive ventilation (IV), and High Flow Therapy (HFT) have been used to treat one or more of the above respiratory disorders.2.2.2.1 Respiratory pressure therapies

[0008] Respiratory pressure therapy is the application of a supply of air to an entrance to the airways at a controlled target pressure that is nominally positive with respect to atmosphere throughout the patient’s breathing cycle (in contrast to negative pressure therapies such as the tank ventilator or cuirass).

[0009] 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.

[0010] Non-invasive ventilation (NIV) provides ventilatory support to a patient through the upper airways to assist the patient breathing and / or maintain adequate oxygen levels in the body by doing some or all of the work of breathing. The ventilatory support is provided via a non-invasive patient interface. NIV has been used to treat CSR and respiratory failure, in forms such as OHS, COPD, NMD and Chest Wall disorders. In some forms, the comfort and effectiveness of these therapies may be improved.

[0011] Invasive ventilation (IV) provides ventilatory support to patients that are no longer able to effectively breathe themselves and may be provided using a tracheostomy tube or endotracheal tube. In some forms, the comfort and effectiveness of these therapies may be improved.2.2.2.2 Flow therapies

[0012] Not all respiratory therapies aim to deliver a prescribed therapeutic pressure. Some respiratory therapies aim to deliver a prescribed respiratory volume, by delivering an inspiratory flow rate profile over a targeted duration, possiblysuperimposed on a positive baseline pressure. In other cases, the interface to the patient’s airways is ‘open’ (unsealed) and the respiratory therapy may only supplement the patient’s own spontaneous breathing with a flow of conditioned or enriched gas. In one example, High Flow therapy (HFT) is the provision of a continuous, heated, humidified flow of air to an entrance to the airway through an unsealed or open patient interface at a “treatment flow rate” that may be held approximately constant throughout the respiratory cycle. The treatment flow rate is nominally set to exceed the patient’s peak inspiratory flow rate. HFT has been used to treat OSA, CSR, respiratory failure, COPD, and other respiratory disorders. One mechanism of action is that the high flow rate of air at the airway entrance improves ventilation efficiency by flushing, or washing out, expired CO2 from the patient’s anatomical deadspace. Hence, HFT is thus sometimes referred to as a deadspace therapy (DST). Other benefits may include the elevated warmth and humidification (possibly of benefit in secretion management) and the potential for modest elevation of airway pressures. As an alternative to constant flow rate, the treatment flow rate may follow a profile that varies over the respiratory cycle.

[0013] Another form of flow therapy is long-term oxygen therapy (LTOT) or supplemental oxygen therapy. Doctors may prescribe a continuous flow of oxygen enriched air at a specified oxygen concentration (from 21%, the oxygen fraction in ambient air, to 100%) at a specified flow rate (e.g., 1 litre per minute (LPM), 2 LPM, 3 LPM, etc.) to be delivered to the patient’s airway.2.2.1.3 Supplementary oxygen

[0014] For certain patients, oxygen therapy may be combined with a respiratory pressure therapy or HFT by adding supplementary oxygen to the pressurised flow of air. When oxygen is added to respiratory pressure therapy, this is referred to as RPT with supplementary oxygen. When oxygen is added to HFT, the resulting therapy is referred to as HFT with supplementary oxygen.2.2.3 Respiratory Therapy Systems

[0015] 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.

[0016] 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

[0017] 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 cmlhO 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 cmFFO. For flow therapies such as nasal HFT, the patient interface is configured to insufflate the nares but specifically to avoid a complete seal. One example of such a patient interface is a nasal cannula.2.2.3.2 Respiratory Pressure Therapy (RPT) Device

[0018] A respiratory pressure therapy (RPT) device may be used individually or as part of a system to deliver one or more of a number of therapies described above, such as by operating the device to generate a flow of air for delivery to an interface to the airways. The flow of air may be pressure-controlled (for respiratory pressure therapies) or flow-controlled (for flow therapies such as HFT). Thus RPT devices may also act as flow therapy devices. Examples of RPT devices include a CPAP device and a ventilator.

[0019] Air pressure generators are known in a range of applications, e.g. industrial-scale ventilation systems. However, air pressure generators for medical applications have particular requirements not fulfilled by more generalised air pressure generators, such as the reliability, size and weight requirements of medical devices. In addition, even devices designed for medical treatment may suffer from shortcomings, pertaining to one or more of comfort, noise, ease of use, efficacy, size, weight, manufacturability, cost, and reliability.

[0020] An example of the special requirements of certain RPT devices is acoustic noise.

[0021] Table of noise output levels of prior RPT devices (one specimen only, measured using test method specified in ISO 3744 in CPAP mode at 10 cmH20).

[0022] One known RPT device used for treating sleep disordered breathing is the S9 Sleep Therapy System, manufactured by ResMed Inc. Another example of an RPT device is a ventilator. Ventilators such as the ResMed Stellar™ Series of Adult and Paediatric Ventilators may provide support for invasive and non-invasive nondependent ventilation for a range of patients for treating a number of conditions such as but not limited to NMD, OHS and COPD.

[0023] 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.

[0024] The designer of a device may be presented with an infinite number of choices to make. Design criteria often conflict, meaning that certain design choices 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.2.2.3.3 Air circuit

[0025] An air circuit is a conduit or a tube constructed and arranged to allow, in use, a flow of air to travel between two components of a respiratory therapy systemsuch as the RPT device and the patient interface. In some cases, there may be separate limbs of the air circuit for inhalation and exhalation. In other cases, a single limb air circuit is used for both inhalation and exhalation.2.1.3.4 Humidifier

[0026] 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.

[0027] A range of artificial humidification devices and systems are known, however they may not fulfil the specialised requirements of a medical humidifier.

[0028] Medical humidifiers are used to increase humidity and / or temperature of the flow of air in relation to ambient air when required, typically where the patient may be asleep or resting (e.g. at a hospital). A medical humidifier for bedside placement may be small. A medical humidifier may be configured to only humidify and / or heat the flow of air delivered to the patient without humidifying and / or heating the patient’s surroundings. Room-based systems (e.g. a sauna, an air conditioner, or an evaporative cooler), for example, may also humidify air that is breathed in by the patient, however those systems would also humidify and / or heat the entire room, which may cause discomfort to the occupants. Furthermore, medical humidifiers may have more stringent safety constraints than industrial humidifiers

[0029] 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.

[0030] Providing a patient mounted humidification system may create additional challenges. Patient mounted examples may need to be much smaller and lighter than traditional humidifier systems, which are intended to be located on a bedside table. Some patient mounted humidifier systems may be battery powered, in which case it may be important to minimise power consumption. Furthermore, because the patient may sleep in any one (or more) of a variety of different positions (on the back, on the side etc.) it may not be convenient to use a humidifier which directs air over a free surface of a liquid in a reservoir, since the orientation of the free surface relative to the structure of the apparatus (e.g. inlet and outlet air ports) may change.2.1.3.5 Data Management

[0031] There may be clinical reasons to obtain data to determine whether the patient prescribed with respiratory therapy has been “compliant”, e.g. that the patient has used their RPT device according to one or more “compliance rules”. One example of a compliance rule for CPAP therapy is that a patient, in order to be deemed compliant, is required to use the RPT device for at least four hours a night for at least 21 of 30 consecutive days. In order to determine a patient's compliance, a provider of the RPT device, such as a health care provider, may manually obtain data describing the patient's therapy using the RPT device, calculate the usage over a predetermined time period, and compare with the compliance rule. Once the health care provider has determined that the patient has used their RPT device according to the compliance rule, the health care provider may notify a third party that the patient is compliant.

[0032] There may be other aspects of a patient’s therapy that would benefit from communication of therapy data to a third party or external system.

[0033] Existing processes to communicate and manage such data can be one or more of costly, time-consuming, and error-prone.2.1.3.6 Vent technologies

[0034] Some forms of treatment systems may include a vent to allow the washout of exhaled carbon dioxide. The vent may allow a flow of gas from an interior space of a patient interface, e.g., the plenum chamber, to an exterior of the patient interface, e.g., to ambient.2.2.4 Screening, Diagnosis, and Monitoring Systems

[0035] Polysomnography (PSG) is a conventional system for diagnosis and monitoring of cardio-pulmonary disorders, and typically involves expert clinical staff to apply the system. PSG typically involves the placement of 15 to 20 contact sensors on a patient in order to record various bodily signals such as electroencephalography (EEG), electrocardiography (ECG), electrooculograpy (EOG), electromyography (EMG), etc. PSG for sleep disordered breathing has involved two nights of observation of a patient in a clinic, one night of pure diagnosis and a second night of titration of treatment parameters by a clinician. PSG is therefore expensive and inconvenient. In particular, it is unsuitable for home screening / diagnosis / monitoring of sleep disordered breathing.

[0036] Screening and diagnosis generally describe the identification of a condition from its signs and symptoms. Screening typically gives a true / false result indicating whether or not a patient’s SDB is severe enough to warrant further investigation, while diagnosis may result in clinically actionable information. Screening and diagnosis tend to be one-off processes, whereas monitoring the progress of a condition can continue indefinitely. Some screening / diagnosis systems are suitable only for screening / diagnosis, whereas some may also be used for monitoring.

[0037] Clinical experts may be able to screen, diagnose, or monitor patients adequately based on visual observation of PSG signals. However, there are circumstances where a clinical expert may not be available, or a clinical expert may not be affordable. Different clinical experts may disagree on a patient’s condition. In addition, a given clinical expert may apply a different standard at different times.3 BRIEF SUMMARY OF THE TECHNOLOGY

[0038] 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.

[0039] A first aspect of the present technology relates to apparatus used in the screening, diagnosis, monitoring, amelioration, treatment or prevention of a respiratory disorder.

[0040] Another aspect of the present technology relates to methods used in the screening, diagnosis, monitoring, amelioration, treatment or prevention of a respiratory disorder.

[0041] 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.

[0042] One form of the present technology comprises a positioning and stabilising structure configured to provide a force to hold the seal-forming structure in a therapeutically effective position on the patient’s head. The positioning and stabilising structure includes at least one strap.

[0043] One form of the present technology comprises a patient interface comprising a plenum chamber, a seal-forming structure, and a positioning and stabilising structure.

[0044] One form of the present technology comprises a patient interface comprising a plenum chamber pressurisable to a therapeutic pressure of at least 4 cmH20 above ambient air pressure. The plenum chamber includes at least one plenum chamber inlet port sized and structured to receive a flow of air at the therapeutic pressure for breathing by a patient. The patient interface also comprises a seal-forming structure that is constructed and arranged to form a seal with a region of the patient’s face surrounding an entrance to the patient’s airways. The seal-forming structure has a hole therein such that the flow of air at said therapeutic pressure is delivered to at least an entrance to the patient’s nares. The seal-forming structure is constructed and arranged to maintain said therapeutic pressure in the plenum chamber throughout the patient’s respiratory cycle in use. The patient interface also comprises a positioning and stabilising structure to provide a force to hold the seal-forming structure in a therapeutically effective position on the patient’s head.

[0045] Another aspect of one form of the present technology is a series of modular elements that may be interconnected in order to form different styles of patient interfaces.

[0046] In one form, there are at least two versions or styles of each modular element. The versions or styles may be interchangeably used with one another in order to form different modular assemblies.

[0047] One form of the present technology comprises a humidifier for a respiratory therapy apparatus comprising, an air passage for a gas to be humidified, the air passage having an inlet and outlet, a humidifier reservoir for containing a volume of water, a nozzle having an internal passage, wherein an inlet of the nozzle is in fluid communication with the humidifier reservoir, and an outlet of the nozzle is within the air passage, and the nozzle comprising a transducer, wherein the transducer is configured to change a volume of the internal passage of the nozzle, to thereby eject a water droplet from the nozzle outlet.

[0048] In examples:- the nozzle is configured to direct the water droplet onto a surface of the air passage;- the transducer is a piezoelectric transducer;- the transducer is provided to an external surface of the nozzle;- the transducer is provided to an internal surface of the nozzle; and / or the nozzle outlet has a diameter of no more than 1mm, more preferably less than 300pm, more preferably less than 150 pm, more preferably less than 50 pm.

[0049] Another aspect of one form of the present technology comprises a humidifier for a respiratory therapy apparatus comprising, an air passage for a gas to be humidified, the air passage having an inlet and outlet, a humidifier reservoir for containing a volume of water, a water outlet member in fluid communication with the humidifier reservoir, the water outlet member comprising a plurality of outlet apertures, each outlet aperture having a diameter of no more than 1mm, wherein the outlet apertures are within the air passage, the apparatus further comprising a transducer configured to increase a pressure of the water when activated, to thereby cause a volume of the water to pass through the outlet apertures into the air passage.

[0050] In examples:- the transducer is provided within the humidifier reservoir;- the water outlet member is connected to the humidifier reservoir by a conduit, and the transducer is provided within the conduit; and / or- the transducer is a piezoelectric transducer.

[0051] Another aspect of one form of the present technology comprises a humidifier for a respiratory therapy apparatus comprising,an air passage for a gas to be humidified, the air passage having an inlet and outlet, a humidifier reservoir for containing a volume of water, a water outlet member in fluid communication with the humidifier reservoir, the water outlet member comprising a plurality of outlet apertures, each outlet aperture having a diameter of no more than 1mm, wherein the outlet apertures are within the air passage, the apparatus further comprising a transducer configured to displace or deform the water outlet member when activated, to thereby cause a volume of the water to pass through the outlet apertures into the air passage.

[0052] In examples:- the transducer is a piezoelectric transducer.

[0053] Another aspect of one form of the present technology comprises a humidifier for a respiratory therapy apparatus comprising, an air passage for a gas to be humidified, the air passage having an inlet and outlet, a humidifier reservoir for containing a volume of water, a wicking material provided within the air passage and in fluid communication with the humidifier reservoir, and a heating element in contact with the wicking material and configured to heat the water present in the wicking material.

[0054] In examples:- the wicking material comprises one or more of fluted paper, woven textile, non-woven textile, open cell foam, woven mesh and / or metal mesh and / or- the wicking material surrounds the heating element.

[0055] Another aspect of one form of the present technology is a patient interface for treating a patient with a respiratory disorder, comprising: a respiratory pressure therapy (RPT) device including an electric blower configured to generate pressurized breathable air; a seal -forming structure configured to form a seal against the patient’s face, the seal-forming structure at least partially defining a plenum chamber configured to receive the pressurized air; a flow generator casing that at least partly encloses the electric blower and is connected to the plenum chamber, the casing including at least one air opening to receive ambient air for delivery to the RPT device; a humidifier provided to an air path between the flow generator and the plenum chamber; and a positioning and stabilising structure configured to maintain the sealforming structure and the blower in a therapeutically effective position.

[0056] In examples;- the humidifier is depowered or switched off during at least part of the patient’s breathing cycle; and / or- the humidifier is depowered or switched off during at least part of an exhalation phase of the patient's breathing cycle.

[0057] Another aspect of one form of the present technology is a patient interface that is moulded or otherwise constructed with a perimeter shape which is complementary to that of an intended wearer.

[0058] An aspect of one form of the present technology is a method of manufacturing apparatus.

[0059] Another aspect of one form of the present technology is a method of assembling a modular system comprising selecting a positioning and stabilising structure, and connecting the positioning and stabilising structure to either a first cushion or a second cushion.

[0060] An aspect of certain forms of the present technology is a medical device that is easy to use, e.g. by a person who does not have medical training, by a personwho has limited dexterity, vision or by a person with limited experience in using this type of medical device.

[0061] An aspect of one form of the present technology is a portable RPT device that may be carried by a person, e.g., around the home of the person.

[0062] An aspect of one form of the present technology is a patient interface that may be washed in a home of a patient, e.g., in soapy water, without requiring specialised cleaning equipment. An aspect of one form of the present technology is a humidifier tank that may be washed in a home of a patient, e.g., in soapy water, without requiring specialised cleaning equipment.

[0063] The methods, systems, devices and apparatus described may be implemented so as to improve the functionality of a processor, such as a processor of a specific purpose computer, respiratory monitor and / or a respiratory therapy apparatus. Moreover, the described methods, systems, devices and apparatus can provide improvements in the technological field of automated management, monitoring and / or treatment of respiratory conditions, including, for example, sleep disordered breathing.

[0064] 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.

[0065] 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

[0066] 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

[0067] Fig. 1 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.4.2 RESPIRATORY SYSTEM AND FACIAL ANATOMY

[0068] Fig. 2 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.4.3 PATIENT INTERFACE

[0069] Fig. 3 shows a patient interface in the form of a nasal mask in accordance with one form of the present technology.4.4 RPT DEVICE

[0070] Fig. 4A shows an RPT device in accordance with one form of the present technology.

[0071] 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.

[0072] Fig. 4C is a schematic diagram of the electrical components of an RPT device in accordance with one form of the present technology.

[0073] Fig. 4C-1 is a schematic diagram illustrating the interconnection of various electrical components of the RPT device.

[0074] Fig. 4D is a schematic diagram of the algorithms implemented in an RPT device in accordance with one form of the present technology.

[0075] Fig. 4E is a flow chart illustrating a method carried out by the therapy engine module of Fig. 4D in accordance with one form of the present technology.4.5 HUMIDIFIER

[0076] Fig. 5A shows an isometric view of a humidifier in accordance with one form of the present technology.

[0077] 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.

[0078] Fig. 5C shows a schematic of a humidifier in accordance with one form of the present technology.4.6 BREATHING WAVEFORMS

[0079] Fig. 6 shows a model typical breath waveform of a person while sleeping.4.7 PATIENT INTERFACE WITH INTEGRATED BLOWER

[0080] Fig. 7 shows a perspective view of one example of a patient interface with an integrated blower.

[0081] Fig. 8 shows an exploded view of the patient interface of Fig. 7.4.8 HUMIDIFIERS OF THE PRESENT TECHNOLOGY

[0082] Fig. 9 shows a diagrammatic cross-section view of a humidifier according to one form of the technology.

[0083] Fig. 10A shows a diagrammatic cross-section view of a humidifier according to another form of the technology.

[0084] Fig. 10B shows a diagrammatic cross-section view of a humidifier according to another form of the technology.

[0085] Fig. 11 shows a diagrammatic cross-section view of a humidifier according to another form of the technology.5 DETAILED DESCRIPTION OF EXAMPLES OF THETECHNOLOGY

[0086] 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.

[0087] 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

[0088] In one form, the present technology comprises a method for treating a respiratory disorder comprising applying positive pressure to the entrance of the airways of a patient 1000.

[0089] 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.

[0090] In certain examples of the present technology, mouth breathing is limited, restricted or prevented.5.2 RESPIRATORY THERAPY SYSTEMS

[0091] In one form, the present technology comprises a respiratory therapy system for treating a respiratory disorder. The respiratory therapy system may comprise an RPT device 4000 for supplying a flow of air to the patient 1000 via an air circuit 4170 and a patient interface 3000.5.3 PATIENT INTERFACE

[0092] A non-invasive patient interface 3000, such as that shown in Fig. 3, in accordance with one aspect of the present technology comprises the following functional aspects: a seal-forming structure 3100, a plenum chamber 3200, a positioning and stabilising structure 3300, a vent 3400, one form of connection port 3600 for connection to air circuit 4170, and a forehead support 3700. In some forms a functional aspect may be provided by one or more physical components. In some forms, one physical component may provide one or more functional aspects. In use the seal -forming structure 3100 is arranged to surround an entrance to the airways of the patient so as to maintain positive pressure at the entrance(s) to the airways of the patient 1000. The sealed patient interface 3000 is therefore suitable for delivery of positive pressure therapy.5.3.1 Self-Contained Patient Interface

[0093] As illustrated in Figs. 7 and 8, some forms of the technology the patient interface 6000 may comprise a self-contained unit. For example, the patient interfaces may not need to be connected to an external device to receive a flow of pressurized air. Instead, the patient interface itself may include a motor for delivering pressurized airflow directly to a patient.

[0094] In some forms, this may enable the patient interface to be more portable, which may be particularly beneficial for patients who travel. For example, the patient may be able to pack a smaller, more portable component. This may promote the continuance of therapy while the patient is away from home.

[0095] In some forms, the self-contained patient interface may promote better sleep in the patient or in a bed partner. For example, the patient may not be tethered to an RPT device, which could restrict movement while sleeping. This may allow the patient to roll or otherwise move while sleeping without being constrained. Similarly, the patient’s bed partner may experience a better sleep if the patient is able to sleep throughout the night.

[0096] In certain forms, a patient (and / or the patient’s bed partner) may dislike the intrusiveness of wires, tubes, and / or cords, and may find the medical appearance of the patient interface aesthetically unappealing. This could lead to lower compliance with the therapy. By reducing the external attachments on the self-contained patient interface, a patient may be more likely to use the patient interface. For example, as described below, the material of the patient interface, combined with the lack of external attachments, may reduce the medical feel of the patient interface.

[0097] In some forms, providing a single unit may be more intuitive for a patient to use. For example, the patient may need to interact with a single device, which may simplify the steps necessary to learn how to use the device.

[0098] Self-contained patient interfaces of this type are described in PCT Publication WO2023077192, the contents of which are included herein by reference in their entirety.

[0099] As described below, the patient interfaces 6000 illustrated in Figs. 7 and 8 may be similar to the patient interface 3000 described above (see e.g., Fig. 3), and only some similarities and differences may be described.5.3.1.1 Full-face Self Contained Interface

[0100] As illustrated in Figs. 7 and 8, some forms of the patient interface are a full-face patient interface. For example, the patient interface may form a seal around the patient’s nares and the patient’s mouth so that pressurized air may be delivered to the patient’s airways through either the patient’s nose and / or the patient’s mouth.

[0101] As illustrated in Figs. 7 and 8, a first version of a full-face patient interface 6000 may include a seal -forming structure 6100, a plenum chamber 6200, a positioning and stabilising structure 6300, and a flow generator casing 6400.

[0102] The seal-forming structure 6100 may be constructed from a flexible material and may be comfortable when contacting the patient’s face. For example, the seal-forming structure 6100 may be formed from a silicone material. Alternatively or additionally, the seal -forming structure 6100 may be formed from a textile material. The seal-forming structure may have a frame made of a more rigid material (e.g., plastic or polycarbonate) than the seal portion, and the frame may be attached to the casing 6400. The seal portion and / or the frame may have a gas washout vent with one or more holes to exhaust exhaled gas to ambient. Moreover, especially in the case where the patient interface is a full face mask or oro-nasal mask, the seal-forming structure and / or the casing (described below) may include an anti-asphyxia valve (AAV) to allow the patient to breath in ambient air if the patient interface is not connected to a power source (e.g., due to a power outage).

[0103] In the illustrated example, the seal-forming structure 6100 may have a substantially low profile. As described above, a patient may feel uncomfortable wearing a large device, and may therefore be dissuaded from continuing the therapy. The seal-forming structure 6100 may therefore minimize the sealing area (e.g., area within the seal-forming structure 6100).

[0104] In certain forms, the nasal seal 6104 of the seal-forming structure 6100 may not contact a ridge of the patient’s nose. For example, the seal-forming structure 6100 may seal around the patient’s alar rims while avoiding contact with the patient’s nasal ridge. Patients may find this more comfortable because less of their face is in contact with the seal and subjected to the therapeutic pressure.

[0105] In some forms, the seal -forming structure 6100 may not extend substantially beyond the plenum chamber 6200 and / or the flow generator casing 6400. For example, a height of the plenum chamber 6200 and / or the flow generator casing 6400 may be substantially the same as the height of the sealing area (e.g., measuredfrom the patient’s lip inferior to the pronasal e). In other examples, the plenum chamber 6200 and / or the flow generator casing 6400 may extend inferior to the sealforming structure 6100 (e.g., toward the supramenton) but may not extend substantially superior to the seal-forming structure (e.g., above the pronasale and onto the patient’s nasal ridge). This may assist in contributing to a low profile of the patient interface 6000. For example, the plenum chamber 6200 and / or the flow generator casing 6400 may not substantially obstruct the patient’s line of sight.

[0106] In some forms, the positioning and stabilising structure 6300 may be connected to the flow generator casing 6400. The plenum chamber 6200 and the sealforming structure 6100 are connected to the flow generator casing 6400. The positioning and stabilising structure 6300 may therefore provide a tensile force for maintaining the seal-forming structure 6100 in a sealing position on the patient’s face.

[0107] The positioning and stabilising structure 6300 may be formed as a headgear and may include a front strap 6304. The front strap 6304 may contact the patient’s face between the respective eye and ear and pass over top of the patient’s head. In other words, the front strap 6304 may contact the patient’s cheeks and may overlay the frontal bone and / or the parietal bone on the patient’s head.

[0108] In some forms, the front strap 6304 may include ends 6308 that connect to the flow generator casing 6400. In some examples, the ends 6308 may be permanently connected (e.g., via an adhesive, stitching, welding, etc.) to the flow generator casing 6400. In other examples, the ends 6308 may be removably connected (e.g., via a mechanical fastener, hook and look material, magnets, etc.) to the flow generator casing 6400. Although not shown, the ends 6308 may alternatively be connected directly to the plenum chamber 6200 (e.g., either removably or permanently).

[0109] In some forms, the front strap 6304 may be constructed from a textile or other comfortable material (e.g., a material that is flexible and soft to the touch). The textile material may promote patient compliance because it more closely resembles bed clothes and not a medical device. The improved comfort as well as the aesthetically pleasing look may encourage patients to continue to wear the patient interface 6000 and continue the therapy.

[0110] As indicated in Fig. 7, certain forms of the front strap 6304 may include one or more rigidizers 6312.

[0111] In some forms, the positioning and stabilising structure 6300 may further include an upper back strap 6316. The upper back strap 6316 may contact a posteriorportion of the patient’s head in use. For example, the upper back strap 6316 may contact the patient’s head superior to a respective ear (e.g., overlaying a temporal bone) and extend toward the back of the patient’s head (e.g., overlaying the occipital bone).

[0112] In some forms, the upper back strap 6316 may connect to the front strap 6304. For example, the upper back strap 6316 may connect to the front strap 6304 at a location superior to the patient’s ear in use (e.g., so that the upper back strap 6316 does not intersect with the patient’s ear). In some forms, the upper back strap 6316 may be permanently connected to the front strap 6304, while in other examples, the upper back strap 6316 may be removably connected to the front strap 6304.

[0113] In some forms, the positioning and stabilising structure 6300 may further include a lower back strap 6320. The lower back strap 6320 may contact a posterior portion of the patient’s head in use. For example, the lower back strap 6320 may contact the patient’s head inferior to a respective ear (e.g., overlaying the masseter muscle) and extend toward the back of the patient’s head (e.g., overlaying the occipital bone).

[0114] As illustrated in Fig. 7, a connector strap 6324 may connect the upper and lower back straps 6316, 6320. The connector strap 6324 may overlay the patient’s occipital bone in use. The connector strap 6324 may limit the relative movement between the upper and lower back straps 6316, 6320.5.3.1.2 Power source

[0115] A patient wearing a patient interface may feel uncomfortable surrounded by cables or wires. The cables or wires may constrain the patient’s movement while wearing the device. The wires and cables may also give the patient interface a medical feel that may contribute to decreased compliance.

[0116] However, the wires and cables generally connect the patient interface to an RPT device, which requires electrical power to supply a flow of pressurized air. The self-contained patient interfaces described above include a flow generator (e.g., within the flow generator casing 6400), but still require a power source in order to operate.

[0117] The illustrated examples are therefore capable of providing power to the patient interface without substantially diminishing the aesthetically pleasing elements for promoting compliance described above.5.3.1.2.1 Connected power source

[0118] In the example shown in Figs. 7 and 8, a battery 6030 may be provided for providing power to an embodiment of the patient interface. The battery 6030 may store an electrical charge, which may be used to power electrical elements of the patient interface (e.g., the flow generator, sensors, etc.). An electrical conductor, e.g. wire, may extend from the battery, along a strap of the positioning and stabilising structure, to the blower.

[0119] In some forms, the battery 6030 is a rechargeable battery and may be reused numerous times. In other forms, the battery 6030 is a single use battery and must be replaced after a predetermined number of usage hours.

[0120] The battery 6030 may be connected directly to the respective patient interface. In other words, a power cord may not be required to connect the battery to the patient interface in order to power the various electrical components (although other examples may not include battery 6030 and may be powered by a remote power source via a power cord).

[0121] In the illustrated examples, the superior region of the front strap 6304 (e.g., the portion overlaying the frontal bone and / or the parietal bone) may include a battery dock. The battery dock may have a complementary shape to the battery 6030 so that the battery 6030 may be removably received on the battery dock.

[0122] In some forms, a button 6314 may be positioned proximate to the battery dock, and may engage a latch which allows the battery 6030 to be disengaged from a battery dock which is provided to the headgear. The projection may engage the battery 6030 and retain it in position. The button 6314 may be actuated in order to move a projection relative to the battery 6030, so that the battery 6030 may be removed from the battery dock (e.g., in order to be recharged and / or replaced).

[0123] In some forms, the battery 6030 may be covered or encased in a textile material (e.g., the same or similar material as the front strap 6304). This may give the patient interface with the battery 6030 a similar non -medical feel as the positioning and stabilising structure.5.4 RPT DEVICE

[0124] An RPT device 4000 in accordance with one aspect of the present technology comprises mechanical, pneumatic, and / or electrical components and is configured to execute one or more algorithms 4300, such as any of the methods, inwhole or in part, described herein. The RPT device 4000 may be configured to generate a flow of air for delivery to a patient’s airways, such as to treat one or more of the respiratory conditions described elsewhere in the present document.

[0125] In one form, the RPT device 4000 is constructed and arranged to be capable of delivering a flow of air in a range of -20 L / min to +150 L / min while maintaining a positive pressure of at least 4 cmH20, or at least 10cmH2O, or at least 20 cmH20.

[0126] 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.

[0127] 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.

[0128] 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.

[0129] As shown in Fig. 4C, 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

[0130] 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)

[0131] 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.

[0132] 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.

[0133] 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 3000.5.4.1.2 Muffler(s)

[0134] An RPT device in accordance with one form of the present technology may include a muffler 4120, or a plurality of mufflers 4120.

[0135] 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.

[0136] 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 3000.5.4.1.3 Pressure generator

[0137] 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.

[0138] The pressure generator 4140 may be under the control of the therapy device controller 4240.

[0139] 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)

[0140] Transducers may be internal of the RPT device, or external of the RPT device. External transducers may be located for example on or form part of the air circuit, e.g., the patient interface. External transducers may be in the form of noncontact sensors such as a Doppler radar movement sensor that transmit or transfer data to the RPT device.

[0141] 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.

[0142] In one form of the present technology, one or more transducers 4270 may be located proximate to the patient interface 3000.

[0143] 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

[0144] 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.

[0145] In one form, a signal generated by the flow rate sensor 4274 and representing a flow rate is received by the central controller 4230.5.4.1.4.2 Pressure sensor

[0146] 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.

[0147] 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

[0148] 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 thetherapy 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

[0149] 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 4144.5.4.2 RPT device electrical components5.4.2.1 Power supply

[0150] A power supply 4210 may be located internal or external of the external housing 4010 of the RPT device 4000.

[0151] 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.

[0152] As illustrated in Fig. 4C-1, the power supply 4210 may provide electrical power to the input device 4220, the central controller 4230, the output device 4290, and the pressure generator 4140. The power supply 4210 may also provide electric energy to other components of the RPT device 4000 (or the humidifier 5000, as described above).5.4.2.1 Input devices

[0153] 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.

[0154] 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.5.4.1.3 Central controller

[0155] 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. The central controller 4230 is show in Figs. 4C and 4C-1.

[0156] 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.

[0157] In one form of the present technology, the central controller 4230 is a dedicated electronic circuit.

[0158] In one form, the central controller 4230 is an application-specific integrated circuit. In another form, the central controller 4230 comprises discrete electronic components.

[0159] The central controller 4230 may be configured to receive input signal(s) from one or more transducers 4270, one or more input devices 4220, and / or the humidifier 5000.

[0160] 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 device controller 4240, a data communication interface 4280, and / or the humidifier 5000.

[0161] 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.5.4.1.4 Clock

[0162] The RPT device 4000 may include a clock 4232 that is connected to the central controller 4230.5.4.1.5 Therapy device controller

[0163] In one form of the present technology, therapy device controller 4240 is a therapy control module 4330 that forms part of the algorithms 4300 executed by the central controller 4230.

[0164] 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.5.4.1.6 Protection circuits

[0165] 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.5.4.1.7 Memory

[0166] 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.

[0167] Memory 4260 may be located on the PCBA 4202. Memory 4260 may be in the form of EEPROM, or NAND flash.

[0168] 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.

[0169] 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 4300.5.4.1.8 Data communication systems

[0170] 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 remoteexternal device 4286. The local external communication network 4284 may be connectable to a local external device 4288.

[0171] 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.

[0172] 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.

[0173] In one form, local external communication network 4284 utilises one or more communication standards, such as Bluetooth, or a consumer infrared protocol.

[0174] 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.

[0175] The local external device 4288 may be a personal computer, mobile phone, tablet or remote control.5.4.1.9 Output devices including optional display, alarms

[0176] 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

[0177] 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

[0178] 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.5.4.3 RPT device algorithms

[0179] As mentioned above, in some forms of the present technology, the central controller 4230 may be configured to implement one or more algorithms 4300 expressed as computer programs stored in a non-transitory computer readable storage medium, such as memory 4260. The algorithms 4300 are generally grouped into groups referred to as modules.

[0180] In other forms of the present technology, some portion or all of the algorithms 4300 may be implemented by a controller of an external device such as the local external device 4288 or the remote external device 4286. In such forms, data representing the input signals and / or intermediate algorithm outputs necessary for the portion of the algorithms 4300 to be executed at the external device may be communicated to the external device via the local external communication network 4284 or the remote external communication network 4282. In such forms, the portion of the algorithms 4300 to be executed at the external device may be expressed as computer programs, such as with processor control instructions to be executed by one or more processor(s), stored in a non-transitory computer readable storage medium accessible to the controller of the external device. Such programs configure the controller of the external device to execute the portion of the algorithms 4300.

[0181] In such forms, the therapy parameters generated by the external device via the therapy engine module 4320 (if such forms part of the portion of the algorithms 4300 executed by the external device) may be communicated to the central controller 4230 to be passed to the therapy control module 4330.5.4.3.1 Pre-processing module

[0182] A pre-processing module 4310 in accordance with one form of the present technology receives as an input a signal from a transducer 4270, for example a flow rate sensor 4274 or pressure sensor 4272, and performs one or more process steps to calculate one or more output values that will be used as an input to another module, for example a therapy engine module 4320.

[0183] In one form of the present technology, the output values include the interface pressure Pm, the vent flow rate Qv, the respiratory flow rate Qr, and the leak flow rate QI.

[0184] In various forms of the present technology, the pre-processing module 4310 comprises one or more of the following algorithms: interface pressureestimation 4312, vent flow rate estimation 4314, leak flow rate estimation 4316, and respiratory flow rate estimation 4318.5.4.3.1.1 Interface pressure estimation

[0185] In one form of the present technology, an interface pressure estimation algorithm 4312 receives as inputs a signal from the pressure sensor 4272 indicative of the pressure in the pneumatic path proximal to an outlet of the pneumatic block (the device pressure Pd) and a signal from the flow rate sensor 4274 representative of the flow rate of the airflow leaving the RPT device 4000 (the device flow rate Qd). The device flow rate Qd, absent any supplementary gas 4180, may be used as the total flow rate Qt. The interface pressure algorithm 4312 estimates the pressure drop AP through the air circuit 4170. The dependence of the pressure drop AP on the total flow rate Qt may be modelled for the particular air circuit 4170 by a pressure drop characteristic AP(Q). The interface pressure estimation algorithm, 4312 then provides as an output an estimated pressure, Pm, in the patient interface 3000. The pressure, Pm, in the patient interface 3000 or 3800 may be estimated as the device pressure Pd minus the air circuit pressure drop AP.5.4.3.1.2 Vent flow rate estimation

[0186] In one form of the present technology, a vent flow rate estimation algorithm 4314 receives as an input an estimated pressure, Pm, in the patient interface 3000 or 3800 from the interface pressure estimation algorithm 4312 and estimates a vent flow rate of air, Qv, from a vent 3400 in a patient interface 3000. The dependence of the vent flow rate Qv on the interface pressure Pm for the particular vent 3400 in use may be modelled by a vent characteristic Qv(Pm).5.4.3.1.3 Leak flow rate estimation

[0187] In one form of the present technology, a leak flow rate estimation algorithm 4316 receives as an input a total flow rate, Qt, and a vent flow rate Qv, and provides as an output an estimate of the leak flow rate QI. In one form, the leak flow rate estimation algorithm estimates the leak flow rate QI by calculating an average of the difference between total flow rate Qt and vent flow rate Qv over a period sufficiently long to include several breathing cycles, e.g. about 10 seconds.

[0188] In one form, the leak flow rate estimation algorithm 4316 receives as an input a total flow rate Qt, a vent flow rate Qv, and an estimated pressure, Pm, in the patient interface 3000 or 3800, and provides as an output a leak flow rate QI, bycalculating a leak conductance, and determining a leak flow rate QI to be a function of leak conductance and pressure, Pm. Leak conductance is calculated as the quotient of low pass filtered non-vent flow rate equal to the difference between total flow rate Qt and vent flow rate Qy, and low pass filtered square root of pressure Pm, where the low pass filter time constant has a value sufficiently long to include several breathing cycles, e.g. about 10 seconds. The leak flow rate QI may be estimated as the product of leak conductance and a function of pressure, Pm.5.4.3.1.4 Respiratory flow rate estimation

[0189] In one form of the present technology, a respiratory flow rate estimation algorithm 4318 receives as an input a total flow rate, Qt, a vent flow rate, Qy, and a leak flow rate, QI, and estimates a respiratory flow rate of air, Qr, to the patient, by subtracting the vent flow rate Qy and the leak flow rate QI from the total flow rate Qt.5.4.3.1 Therapy Engine Module

[0190] In one form of the present technology, a therapy engine module 4320 receives as inputs one or more of a pressure, Pm, in a patient interface 3000 or 3800, and a respiratory flow rate of air to a patient, Qr, and provides as an output one or more therapy parameters.

[0191] In one form of the present technology, a therapy parameter is a treatment pressure Pt.

[0192] In one form of the present technology, therapy parameters are one or more of an amplitude of a pressure variation, a base pressure, and a target ventilation.

[0193] In various forms, the therapy engine module 4320 comprises one or more of the following algorithms: phase determination 4321, waveform determination 4322, ventilation determination 4323, inspiratory flow limitation determination 4324, apnea / hypopnea determination 4325, snore determination 4326, airway patency determination 4327, target ventilation determination 4328, and therapy parameter determination 4329.5.4.3.2.1 Phase determination

[0194] In one form of the present technology, the RPT device 4000 does not determine phase.

[0195] In one form of the present technology, a phase determination algorithm 4321 receives as an input a signal indicative of respiratory flow rate, Qr, and provides as an output a phase of a current breathing cycle of a patient 1000.

[0196] In some forms, known as discrete phase determination, the phase output is a discrete variable. One implementation of discrete phase determination provides a bi-valued phase output with values of either inhalation or exhalation, for example represented as values of 0 and 0.5 revolutions respectively, upon detecting the start of spontaneous inhalation and exhalation respectively. RPT devices 4000 that “trigger” and “cycle” effectively perform discrete phase determination, since the trigger and cycle points are the instants at which the phase changes from exhalation to inhalation and from inhalation to exhalation, respectively. In one implementation of bi-valued phase determination, the phase output is determined to have a discrete value of 0 (thereby “triggering” the RPT device 4000) when the respiratory flow rate Qr has a value that exceeds a positive threshold, and a discrete value of 0.5 revolutions (thereby “cycling” the RPT device 4000) when a respiratory flow rate Qr has a value that is more negative than a negative threshold. The inhalation time Ti and the exhalation time Te may be estimated as typical values over many respiratory cycles of the time spent with phase equal to 0 (indicating inspiration) and 0.5 (indicating expiration) respectively.

[0197] Another implementation of discrete phase determination provides a trivalued phase output with a value of one of inhalation, mid-inspiratory pause, and exhalation.

[0198] In other forms, known as continuous phase determination, the phase output is a continuous variable, for example varying from 0 to 1 revolutions, or 0 to 2 ;r radians. RPT devices 4000 that perform continuous phase determination may trigger and cycle when the continuous phase reaches 0 and 0.5 revolutions, respectively. In one implementation of continuous phase determination, a continuous value of phase is determined using a fuzzy logic analysis of the respiratory flow rate Qr. A continuous value of phase determined in this implementation is often referred to as “fuzzy phase”. In one implementation of a fuzzy phase determination algorithm 4321, the following rules are applied to the respiratory flow rate Qr.1. is zero and increasing fast then is 0 revolutions.2. If Qr is large positive and steady thenis 0.25 revolutions.3. If Qr is zero and falling fast, then is 0.5 revolutions.4. If Qr is large negative and steady then is 0.75 revolutions.5. If Qr is zero and steady and the 5-second low-pass filtered absolute value of Qr is large then O is 0.9 revolutions.6. If Qr is positive and the phase is expiratory, then O is 0 revolutions.7. If Qr is negative and the phase is inspiratory, then O is 0.5 revolutions.8. If the 5-second low-pass filtered absolute value of Qr is large, O is increasing at a steady rate equal to the patient’s breathing rate, low-pass filtered with a time constant of 20 seconds.

[0199] The output of each rule may be represented as a vector whose phase is the result of the rule and whose magnitude is the fuzzy extent to which the rule is true. The fuzzy extent to which the respiratory flow rate is “large”, “steady”, etc. is determined with suitable membership functions. The results of the rules, represented as vectors, are then combined by some function such as taking the centroid. In such a combination, the rules may be equally weighted, or differently weighted.

[0200] In another implementation of continuous phase determination, the phase O is first discretely estimated from the respiratory flow rate Qr as described above, as are the inhalation time Ti and the exhalation time Te. The continuous phase O at any instant may be determined as the half the proportion of the inhalation time Ti that has elapsed since the previous trigger instant, or 0.5 revolutions plus half the proportion of the exhalation time Te that has elapsed since the previous cycle instant (whichever instant was more recent).5.4.3.2.2 Waveform determination

[0201] In one form of the present technology, the therapy parameter determination algorithm 4329 provides an approximately constant treatment pressure throughout a respiratory cycle of a patient.

[0202] In other forms of the present technology, the therapy control module 4330 controls the pressure generator 4140 to provide a treatment pressure Pt that varies as a function of phase O of a respiratory cycle of a patient according to a waveform template 11( ).

[0203] In one form of the present technology, a waveform determination algorithm 4322 provides a waveform template 11( ) with values in the range [0, 1] on the domain of phase values O provided by the phase determination algorithm 4321 to be used by the therapy parameter determination algorithm 4329.

[0204] In one form, suitable for either discrete or continuously-valued phase, the waveform template 11(0) is a square-wave template, having a value of 1 for values of phase up to and including 0.5 revolutions, and a value of 0 for values of phase above 0.5 revolutions. In one form, suitable for continuously-valued phase, the waveform template 11(0) comprises two smoothly curved portions, namely a smoothly curved (e.g. raised cosine) rise from 0 to 1 for values of phase up to 0.5 revolutions, and a smoothly curved (e.g. exponential) decay from 1 to 0 for values of phase above 0.5 revolutions. In one form, suitable for continuously-valued phase, the waveform template 11( ) is based on a square wave, but with a smooth rise from 0 to 1 for values of phase up to a “rise time” that is less than 0.5 revolutions, and a smooth fall from 1 to 0 for values of phase within a “fall time” after 0.5 revolutions, with a “fall time” that is less than 0.5 revolutions.

[0205] In some forms of the present technology, the waveform determination algorithm 4322 selects a waveform template 11( ) from a library of waveform templates, dependent on a setting of the RPT device. Each waveform template 11( ) in the library may be provided as a lookup table of values II against phase values O. In other forms, the waveform determination algorithm 4322 computes a waveform template 11(0) “on the fly” using a predetermined functional form, possibly parametrised by one or more parameters (e.g. time constant of an exponentially curved portion). The parameters of the functional form may be predetermined or dependent on a current state of the patient 1000.

[0206] In some forms of the present technology, suitable for discrete bi-valued phase of either inhalation (0 = 0 revolutions) or exhalation (O = 0.5 revolutions), the waveform determination algorithm 4322 computes a waveform template II “on the fly” as a function of both discrete phase O and time t measured since the most recent trigger instant. In one such form, the waveform determination algorithm 4322 computes the waveform template 11( , f) in two portions (inspiratory and expiratory) as follows:0 = 00 = 0.5

[0207] where Ili(t) and Flc( / ) are inspiratory and expiratory portions of the waveform template 11(0, f). In one such form, the inspiratory portion Ilf / ) of the waveform template is a smooth rise from 0 to 1 parametrised by a rise time, and theexpiratory portion Hc( / ) of the waveform template is a smooth fall from 1 to 0 parametrised by a fall time.5.4.3.2.3 Ventilation determination

[0208] In one form of the present technology, a ventilation determination algorithm 4323 receives an input a respiratory flow rate Qr, and determines a measure indicative of current patient ventilation, Vent.

[0209] In some implementations, the ventilation determination algorithm 4323 determines a measure of ventilation Vent that is an estimate of actual patient ventilation. One such implementation is to take half the absolute value of respiratory flow rate, Qr, optionally filtered by low-pass filter such as a second order Bessel low- pass filter with a comer frequency of 0.11 Hz.

[0210] In other implementations, the ventilation determination algorithm 4323 determines a measure of ventilation Vent that is broadly proportional to actual patient ventilation. One such implementation estimates peak respiratory flow rate Qpeak over the inspiratory portion of the cycle. This and many other procedures involving sampling the respiratory flow rate Qr produce measures which are broadly proportional to ventilation, provided the flow rate waveform shape does not vary very much (here, the shape of two breaths is taken to be similar when the flow rate waveforms of the breaths normalised in time and amplitude are similar). Some simple examples include the median positive respiratory flow rate, the median of the absolute value of respiratory flow rate, and the standard deviation of flow rate. Arbitrary linear combinations of arbitrary order statistics of the absolute value of respiratory flow rate using positive coefficients, and even some using both positive and negative coefficients, are approximately proportional to ventilation. Another example is the mean of the respiratory flow rate in the middle K proportion (by time) of the inspiratory portion, where 0 < K< 1. There is an arbitrarily large number of measures that are exactly proportional to ventilation if the flow rate shape is constant.5.4.3.2.4 Determination of Inspiratory Flow Limitation

[0211] In one form of the present technology, the central controller 4230 executes an inspiratory flow limitation determination algorithm 4324 for the determination of the extent of inspiratory flow limitation.

[0212] In one form, the inspiratory flow limitation determination algorithm 4324 receives as an input a respiratory flow rate signal Qr and provides as an output ametric of the extent to which the inspiratory portion of the breath exhibits inspiratory flow limitation.

[0213] In one form of the present technology, the inspiratory portion of each breath is identified by a zero-crossing detector. A number of evenly spaced points (for example, sixty-five), representing points in time, are interpolated by an interpolator along the inspiratory flow rate-time curve for each breath. The curve described by the points is then scaled by a scalar to have unity length (duration / period) and unity area to remove the effects of changing breathing rate and depth. The scaled breaths are then compared in a comparator with a pre-stored template representing a normal unobstructed breath, similar to the inspiratory portion of the breath shown in Fig. 6A. Breaths deviating by more than a specified threshold (typically 1 scaled unit) at any time during the inspiration from this template, such as those due to coughs, sighs, swallows and hiccups, as determined by a test element, are rejected. For non -rejected data, a moving average of the first such scaled point is calculated by the central controller 4230 for the preceding several inspiratory events. This is repeated over the same inspiratory events for the second such point, and so on. Thus, for example, sixty-five scaled data points are generated by the central controller 4230, and represent a moving average of the preceding several inspiratory events, e.g., three events. The moving average of continuously updated values of the (e.g., sixty-five) points are hereinafter called the "scaled flow rate ", designated as Qs(t). Alternatively, a single inspiratory event can be utilised rather than a moving average.

[0214] From the scaled flow rate, two shape factors relating to the determination of partial obstruction may be calculated.

[0215] Shape factor 1 is the ratio of the mean of the middle (e.g. thirty -two) scaled flow rate points to the mean overall (e.g. sixty-five) scaled flow rate points. Where this ratio is in excess of unity, the breath will be taken to be normal. Where the ratio is unity or less, the breath will be taken to be obstructed. A ratio of about 1.17 is taken as a threshold between partially obstructed and unobstructed breathing, and equates to a degree of obstruction that would permit maintenance of adequate oxygenation in a typical patient.

[0216] Shape factor 2 is calculated as the RMS deviation from unit scaled flow rate, taken over the middle (e.g. thirty-two) points. An RMS deviation of about 0.2 units is taken to be normal. An RMS deviation of zero is taken to be a totally flow-limited breath. The closer the RMS deviation to zero, the breath will be taken to be more flow limited.

[0217] Shape factors 1 and 2 may be used as alternatives, or in combination. In other forms of the present technology, the number of sampled points, breaths and middle points may differ from those described above. Furthermore, the threshold values can be other than those described.5.4.3.2.5 Determination of apneas and hypopneas

[0218] In one form of the present technology, the central controller 4230 executes an apnea / hypopnea determination algorithm 4325 for the determination of the presence of apneas and / or hypopneas.

[0219] In one form, the apnea / hypopnea determination algorithm 4325 receives as an input a respiratory flow rate signal Qr and provides as an output a flag that indicates that an apnea or a hypopnea has been detected.

[0220] In one form, an apnea will be said to have been detected when a function of respiratory flow rate Qr falls below a flow rate threshold for a predetermined period of time. The function may determine a peak flow rate, a relatively short-term mean flow rate, or a flow rate intermediate of relatively short-term mean and peak flow rate, for example an RMS flow rate. The flow rate threshold may be a relatively long-term measure of flow rate.

[0221] In one form, a hypopnea will be said to have been detected when a function of respiratory flow rate Qr falls below a second flow rate threshold for a predetermined period of time. The function may determine a peak flow, a relatively short-term mean flow rate, or a flow rate intermediate of relatively short-term mean and peak flow rate, for example an RMS flow rate. The second flow rate threshold may be a relatively long-term measure of flow rate. The second flow rate threshold is greater than the flow rate threshold used to detect apneas.5.4.3.2.6 Determination of snore

[0222] In one form of the present technology, the central controller 4230 executes one or more snore determination algorithms 4326 for the determination of the extent of snore.

[0223] In one form, the snore determination algorithm 4326 receives as an input a respiratory flow rate signal Qr and provides as an output a metric of the extent to which snoring is present.

[0224] The snore determination algorithm 4326 may comprise the step of determining the intensity of the flow rate signal in the range of 30-300 Hz. Further, the snore determination algorithm 4326 may comprise a step of filtering the respiratory flow rate signal Qr to reduce background noise, e.g., the sound of airflow in the system from the blower.5.4.3.2. 7 Determination of airway patency

[0225] In one form of the present technology, the central controller 4230 executes one or more airway patency determination algorithms 4327 for the determination of the extent of airway patency.

[0226] In one form, the airway patency determination algorithm 4327 receives as an input a respiratory flow rate signal Qr, and determines the power of the signal in the frequency range of about 0.75 Hz and about 3 Hz. The presence of a peak in this frequency range is taken to indicate an open airway. The absence of a peak is taken to be an indication of a closed airway.

[0227] In one form, the frequency range within which the peak is sought is the frequency of a small forced oscillation in the treatment pressure Pt. In one implementation, the forced oscillation is of frequency 2 Hz with amplitude about 1 cmH20.

[0228] In one form, airway patency determination algorithm 4327 receives as an input a respiratory flow rate signal Qr, and determines the presence or absence of a cardiogenic signal. The absence of a cardiogenic signal is taken to be an indication of a closed airway.5.4.3.2.8 Determination of target ventilation

[0229] In one form of the present technology, the central controller 4230 takes as input the measure of current ventilation, Vent, and executes one or more target ventilation determination algorithms 4328 for the determination of a target value Vtgt for the measure of ventilation.

[0230] In some forms of the present technology, there is no target ventilation determination algorithm 4328, and the target value Vtgt is predetermined, for example by hard-coding during configuration of the RPT device 4000 or by manual entry through the input device 4220.

[0231] In other forms of the present technology, such as adaptive servoventilation (ASV), the target ventilation determination algorithm 4328 computes atarget value Vtgt from a value Vtyp indicative of the typical recent ventilation of the patient.

[0232] In some forms of adaptive servo-ventilation, the target ventilation Vtgt is computed as a high proportion of, but less than, the typical recent ventilation Vtyp. The high proportion in such forms may be in the range (80%, 100%), or (85%, 95%), or (87%, 92%).

[0233] In other forms of adaptive servo-ventilation, the target ventilation Vtgt is computed as a slightly greater than unity multiple of the typical recent ventilation f -

[0234] The typical recent ventilation Vtyp is the value around which the distribution of the measure of current ventilation Vent over multiple time instants over some predetermined timescale tends to cluster, that is, a measure of the central tendency of the measure of current ventilation over recent history. In one implementation of the target ventilation determination algorithm 4328, the recent history is of the order of several minutes, but in any case should be longer than the timescale of Cheyne-Stokes waxing and waning cycles. The target ventilation determination algorithm 4328 may use any of the variety of well-known measures of central tendency to determine the typical recent ventilation Vtyp from the measure of current ventilation, Vent. One such measure is the output of a low-pass filter on the measure of current ventilation Vent, with time constant equal to one hundred seconds.5.4.3.2.9 Determination of therapy parameters

[0235] In some forms of the present technology, the central controller 4230 executes one or more therapy parameter determination algorithms 4329 for the determination of one or more therapy parameters using the values returned by one or more of the other algorithms in the therapy engine module 4320.

[0236] In one form of the present technology, the therapy parameter is an instantaneous treatment pressure Pt. In one implementation of this form, the therapy parameter determination algorithm 4329 determines the treatment pressure Pt using the equation pr= n(< + / l

[0237] where:• A is the amplitude,• 11( , f) is the waveform template value (in the range 0 to 1) at the current value 0 of phase and t of time, and• P is a base pressure.

[0238] If the waveform determination algorithm 4322 provides the waveform template 11( , f) as a lookup table of values II indexed by phase , the therapy parameter determination algorithm 4329 applies equation (1) by locating the nearest lookup table entry to the current value of phase returned by the phase determination algorithm 4321, or by interpolation between the two entries straddling the current value of phase.

[0239] The values of the amplitude A and the base pressure Po may be set by the therapy parameter determination algorithm 4329 depending on the chosen respiratory pressure therapy mode in the manner described below.5.4.3.3 Therapy Control module

[0240] The therapy control module 4330 in accordance with one aspect of the present technology receives as inputs the therapy parameters from the therapy parameter determination algorithm 4329 of the therapy engine module 4320, and controls the pressure generator 4140 to deliver a flow of air in accordance with the therapy parameters.

[0241] In one form of the present technology, the therapy parameter is a treatment pressure Pt, and the therapy control module 4330 controls the pressure generator 4140 to deliver a flow of air whose interface pressure Pm at the patient interface 3000 or 3800 is equal to the treatment pressure Pt.5.4.3.4 Detection of fault conditions

[0242] In one form of the present technology, the central controller 4230 executes one or more methods 4340 for the detection of fault conditions. The fault conditions detected by the one or more methods 4340 may include at least one of the following:• Power failure (no power, or insufficient power)• Transducer fault detection• Failure to detect the presence of a component• Operating parameters outside recommended ranges (e.g. pressure, flow rate, temperature, PaO2)• Failure of a test alarm to generate a detectable alarm signal.

[0243] Upon detection of the fault condition, the corresponding algorithm 4340 signals the presence of the fault by one or more of the following:• Initiation of an audible, visual & / or kinetic (e.g. vibrating) alarm• Sending a message to an external device• Logging of the incident5.4.4 Self-Contained Flow Generator

[0244] As illustrated in Figs. 7 and 8, an RPT device 6500 may be disposed within the flow generator casing 6400 of the patient interface 6000 (or any of the patient interfaces). For example, the RPT device 6500 may be disposed or enclosed within the cavity 6408 formed between the front case 6404 and the rear case 6406. The front case 6404 and the rear case 6406 may be formed from a rigid or semi-rigid material in order to protect the components housed in the cavity 6408.

[0245] In some forms, the RPT device 6500 may include a blower 6502. The blower 6502 may be substantially cylindrical in shape and arranged laterally within the cavity 6408.

[0246] In some forms, the RPT device 6500 may include a suspension 6504. The suspension 6504 may receive and support the blower 6502 within the cavity 6408.

[0247] The suspension 6504 may be formed as a substantially cylindrical body (e.g., similar to the blower 6502) and may include at least a first opening 6506 along a longitudinal direction of the suspension 6504. Only one opening is visible in Figure 8, but the other end of the suspension 6504 may include a second opening (for the opposed impeller on that side). The first opening 6506 may be sized in order to receive the blower 6502, and each first opening is sized to allow intake air from ambient to flow into the respective impeller.

[0248] The suspension 6504 may also include a second opening 6508 that extends tangentially from the cylindrical surface of the suspension 6504. The second opening 6508 may be in fluid communication with the first opening 6506. In use, airflow generated by the blower 6502 and output from the at least one central outlet of the blower 6502 may be forced through the second opening 6504 and toward the plenum chamber 6200. In examples, the air flows through a humidifier 7000 and / or heat and moisture exchanger (HMX) (for example, one of those described below with reference to Figs. 9-11) provided between the blower 6502 and the plenum chamber 6200

[0249] In some forms, an expiratory activated valve (EAV) 6516 may be connected to the manifold 6510. For example, the EAV 6516 may be connected adjacent to the second opening 6514 of the manifold 6510. The EAV 6516 may include at least one airflow path so that the pressurized air exiting the humidifier may continue to be directed toward the plenum chamber 6200.

[0250] The EAV 6516 may be positioned at least partially within an inlet 6518, e.g., in the form of an inlet tube, of the rear case 6406. The plenum chamber 6200 may be connected to the rear case 6406, and the inlet 6518 may extend into the plenum chamber 6200 so that airflow through the inlet 6518 enters the plenum chamber 6200. Thus, there may be an airflow path for delivering the pressurized air from the blower 6502 to the plenum chamber 6200. In examples provide with an HMX, the HMX may be provided in the air path between the EAV 6515 and the entrance to the patient’s airways, e.g, between the EAV 6515 and the plenum chamber 6200. In one example an HMX may be provided in the inlet 6518.

[0251] As illustrated in Fig. 8, the rear case 6406 may include a central groove or recess 6410, which is part of the cavity 6408 when the front case 6404 is connected. The central groove or recess 6410 may be semi -cylindrical in shape, and may be configured to receive the blower 6502 and the suspension 6504. The plenum chamber 6200 includes an anterior surface with a concave section that receives a convex exterior part of the casing or rear case that houses the blower.

[0252] One or more mufflers 6412 may be connected to the rear case 6406 within the cavity 6408 and outside of the central groove 6410. In other words, a muffler 6412 may be positioned at one or both ends of the blower 6502. The mufflers 6512 may assist in reducing the noise output of the blower 6502. This may be useful because the blower 6502 is positioned proximate to the patient’s face and could cause sleep disturbances because of the noise.

[0253] The casing, e.g., rear case 6406 and / or front case 6404, may include outlet vents. Although in other examples, the outlet vents may be included on the rear case 6406. The outlet vents may allow exhaled air to exhaust to ambient.

[0254] In the illustrated example (see e.g., Fig. 8) the rear case 6406 may include an exhaust channel 6416. The EAV 6516 may be smaller than the inlet 6518 so that airflow may pass around the outside of the EAV 6516. The exhausted air flowing around the outside of the EAV 6516 (e.g., air exiting the plenum chamber 6200) maybe directed by the EAV 6516 into the exhaust channel 6416 and through the outlet vents.5.5 AIR CIRCUIT

[0255] An air circuit 4170 in accordance with an aspect of the present technology is a conduit or a tube constructed and arranged to allow, in use, a flow of air to travel between two components such as RPT device 4000 and the patient interface 3000.5.6 HUMIDIFIERS5.6.1 Humidifier overview

[0256] 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.

[0257] The humidifier 5000 may comprise a humidifier reservoir 5110, a humidifier inlet 5002 to receive a flow of air, and a humidifier outlet 5004 to deliver a humidified flow of air. In some forms, as shown in Fig. 5A and Fig. 5B, an inlet and an outlet of the humidifier reservoir 5110 may be the humidifier inlet 5002 and the humidifier outlet 5004 respectively. The humidifier 5000 may further comprise a humidifier base 5006, which may be adapted to receive the humidifier reservoir 5110 and comprise a heating element 5240.5.6.2 Humidifier components5.6.2.1 Water reservoir

[0258] 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.

[0259] In some forms of the technology, 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.

[0260] 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.

[0261] 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.5.6.2.1 Conductive portion

[0262] 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.5.6.1.3 Humidifier reservoir dock

[0263] 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 humidifier reservoir dock 5130.5.6.1.4 Water level indicator

[0264] 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 moreindications 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.5.6.1.5 Humidifier transducer(s)

[0265] 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.5.6.2.5.1 Pressure transducer

[0266] 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 4000.5.6.2.5.2 Flow rate transducer

[0267] 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 4000.5.6.2.5.3 Temperature transducer

[0268] 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.5.6.2.5.4 Humidity transducer

[0269] 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.5.6.1.6 Heating element

[0270] 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.

[0271] 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.5.6.1.7 Humidifier controller

[0272] 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.

[0273] 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.

[0274] 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 5240.5.7 ALTERNATIVE HUMIDIFIERS

[0275] Referring next to Figs. 9 to 11, various alternative humidifiers 7000 are described. These may be particularly suitable for integration into a patient interface 3000, 6000, for example a self contained patient interface 6000 such as that described above with reference to Figs. 7 and 8.

[0276] Referring next to Fig. 9, in one form of the technology the humidifier 7000 may comprise an air passage 7010 having an inlet 7020 and an outlet 7030. The inlet 7020 may receive air from an RPT device. The outlet 7030 may be in fluid communication with a plenum chamber 6200 of a patient interface 6000. In examples, the outlet 7030 may be orientated orthogonally to the inlet 7020.

[0277] The humidifier 7000 comprises a humidifier reservoir 7040 for containing a volume of water. A nozzle 7050 is provided within the air passage 7010 and is in fluid communication with the humidifier reservoir 7040 via a nozzle inlet 7060. The nozzle 7050 may have an outlet 7070 having a diameter of no more than 1mm (i.e. a cross-sectional area of no more than 0.79mm2), for example less than 300pm, less than 150 pm, or less than 50 pm.

[0278] The nozzle 7050 is configured to direct a stream of water droplets from the outlet 7070 onto a landing surface 7080 of the air passage 7010. Air passing over the landing surface 7080 evaporates the water droplets and is humidified.

[0279] In examples, the nozzle 7050 may comprise a transducer, e.g. a piezoelectric transducer 8000. The transducer 8000 may rapidly alter the volume of a passage within the nozzle 7050, thereby causing the nozzle to eject very small droplets. In examples, the transducer 8000 deforms a side wall 8020 of the nozzle 7050 when activated. In other examples, the transducer 8000 is provided within the nozzle passage 8010 and displaces the water in the nozzle passage 8010 when activated. The transducer 8000 may be supplied with high frequency electrical pulses or alternating current in order to generate a large number of small droplets in a short period of time.

[0280] In some examples, particularly where it is important to conserve the water in the reservoir, to reduce rainout and / or to minimise power consumption, the transducer 8000 may only be energised when the patient is inhaling, or at least it may not be energised for a period during each breathing cycle.

[0281] Referring next to Fig. 10 A, another humidifier 7000 is shown which has an air passage 7010 and a humidifier reservoir 7040, similar to that of the example shown in Fig. 9. In the example shown in Fig. 10A, the nozzle 7050 is replaced by a water outlet member 8030. The water outlet member 8030 comprises a plurality ofwater outlet apertures, each having a diameter of no more than 1mm. In examples, the water outlet member 8030 comprises a mesh element. In examples, the water outlet apertures are sufficiently small that surface tension in the water may prevent the water from passing through the mesh unless a pressure of the water exceeds a predetermined threshold.

[0282] In one example, a piezoelectric transducer 8000 is attached to the water outlet member 8030. The transducer 8000 may be activated (with high frequency electrical pulses) to rapidly shake or vibrate the outlet member 8030 (e.g. in a direction transverse to the plane of the outlet member). This vibration may cause atomised water droplets to be forced through the water outlet apertures. The droplets may be of sufficiently small size to form an aerosol in the air flow through the air passage 7010.

[0283] In the example shown in Fig. 10B a piezoelectric transducer 8000 is provided within the reservoir 7040, or in a conduit 8040 provided between the reservoir 7040 and the water outlet member 8030, rather than being attached to the water outlet member 8030. When activated (with high frequency electrical pulses), the transducer 8000 may create pressure waves within the water in the reservoir 7040 which result in water droplets being released through the apertures in the water outlet member 8040.

[0284] In some examples, particularly where it is important to conserve water in the reservoir, to reduce rainout and / or to minimise power consumption, the piezoelectric transducer 8000 may only be energised when the patient is inhaling, or at least it may not be energised for a period during each breathing cycle.

[0285] Referring next to Fig. 11, a humidifier 7000 according to another form of the technology comprises an air passage 7010 and a humidifier reservoir 7040, similar to that of the examples shown in Figs. 9 and 10. In the example of Fig. 11, a heater element 8050 is provided within the air passage 7010. The heater element 8050 is surrounded by a wicking material 8060. The wicking material can be one of or a combination of: fluted paper, woven textile, non-woven textile, open cell foam, woven / metal mesh. In examples, two or more of these materials may be layered or laminated to form a composite.

[0286] The wicking material 8060 is in fluid communication with the humidifier reservoir 7040, such that all, most, or at least some of the wicking material 8060 is kept moist. The air passing through the air passage 7010 evaporates water from the wicking material 8060 and is humidified. The rate of evaporation is determined, in part, by the temperature of the water within the wicking material 8060, and so can be controlled by controlling the temperature of the heating element 8050. In examples, the power supply to the heating element 8050 may be reduced, or disconnected, when the patient is exhaling, or at least the heating element may not be energised for a period during each breathing cycle.

[0287] The humidifier reservoirs 7040 of the examples shown in Figs. 9-11 may comprise a sealable opening (e.g. a lid) so as to be refillable with water. However, in other forms of the technology the reservoir 7040 may be sealed, such that a replacement humidifier 7000, or at least a replacement reservoir, is required when the reservoir is empty, or when it contains less than a minimum required volume of water.

[0288] In examples, the humidifier reservoir 7040 may be filled with a wicking / capillary action material such as open celled sponge material.

[0289] As is noted above with reference to Figs 9-11, in examples the humidifier 7000 may be deactivated or depowered, or at least operated to provide reduced humification, when the patient is exhaling. However, the period of deactivation / reduced humidification may not be exactly synchronized with the patient’s exhalation. For example, it may be convenient to begin powering (or to increase power to) the humidifier 7000 a short period before the patient begins inhaling and / or to deactivate the humidifier 7000 (or at least to reduce humidification) shortly before the patient begins to exhale, or shortly after the patient begins to exhale. In some examples the humidifier may only operate when the flow rate to the patient is greater than a minimum threshold.

[0290] In examples, the air passage 7010 and / or the humidifier reservoir may be provided with disinfecting means. In one form this may comprise an ultraviolet (UV) light source, e.g. a UV LED.5.8 BREATHING WAVEFORMS

[0291] Fig. 6 shows a model typical breath waveform of a person while sleeping. The horizontal axis is time, and the vertical axis is respiratory flow rate. While the parameter values may vary, a typical breath may have the following approximate values: tidal volume Vt 0.5L, inhalation time Ti 1.6s, peak inspiratory flow rate Qpeak 0.4 L / s, exhalation time Te 2.4s, peak expiratory flow rate Qpeak -0.5 L / s. The total duration of the breath, Tlol. is about 4s. The person typically breathes at a rate of about 15 breaths per minute (BPM), with Ventilation Vent about 7.5 L / min. A typical duty cycle, the ratio of Ti to Ttot, is about 40%.5.9 RESPIRATORY THERAPY MODES

[0292] Various respiratory therapy modes may be implemented by the disclosed respiratory therapy system.

[0556] Fig. 4E is a flow chart illustrating a method 4500 carried out by the central controller 4230 to continuously compute the base pressure P0 as part of an APAP therapy implementation of the therapy parameter determination algorithm 4329, when the pressure support A is identically zero.5.10 GLOSSARY

[0293] 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.5.10.1 General

[0294] 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.

[0295] 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.

[0296] 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.

[0297] In another example, ambient pressure may be the pressure immediately surrounding or external to the body.

[0298] 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.

[0299] 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.

[0300] Continuous Positive Airway Pressure (CPAP) therapy. Respiratory pressure therapy in which the treatment pressure is approximately constant through a respiratory cycle of a patient. In some forms, the pressure at the entrance to the airways will be slightly higher during exhalation, and slightly lower during inhalation. In some forms, the pressure will vary between different respiratory cycles of the patient, for example, being increased in response to detection of indications of partial upper airway obstruction, and decreased in the absence of indications of partial upper airway obstruction.

[0301] Flow rate. The volume (or mass) of air delivered per unit time. Flow rate may refer to an instantaneous quantity. In some cases, a reference to flow rate will be a reference to a scalar quantity, namely a quantity having magnitude only. In other cases, a reference to flow rate will be a reference to a vector quantity, namely a quantity having both magnitude and direction. Flow rate may be given the symbol Q. ‘Flow rate’ is sometimes shortened to simply ‘flow’ or ‘airflow’.

[0302] In the example of patient respiration, a flow rate may be nominally positive for the inspiratory portion of a breathing cycle of a patient, and hence negative for the expiratory portion of the breathing cycle of a patient. Device flow rate, Qd, is the flow rate of air leaving the RPT device. Total flow rate, Qt, is the flow rate of air and any supplementary gas reaching the patient interface via the air circuit. Vent flow rate, Qv, is the flow rate of air leaving a vent to allow washout of exhaled gases. Leak flow rate, QI, is the flow rate of leak from a patient interface system or elsewhere. Respiratory flow rate, Qr, is the flow rate of air that is received into the patient's respiratory system.

[0303] Flow therapy. Respiratory therapy comprising the delivery of a flow of air to an entrance to the airways at a controlled flow rate referred to as the treatment flow rate that is typically positive throughout the patient’s breathing cycle.

[0304] Humidifier'. The word humidifier will be taken to mean a humidifying apparatus constructed and arranged, or configured with a physical structure to be capable of providing a therapeutically beneficial amount of water (H2O) vapour to a flow of air to ameliorate a medical respiratory condition of a patient.

[0305] 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.

[0306] Noise, conducted (acoustic) '. Conducted noise in the present document refers to noise which is carried to the patient by the pneumatic path, such as the air circuit and the patient interface as well as the air therein. In one form, conducted noise may be quantified by measuring sound pressure levels at the end of an air circuit.

[0307] 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.

[0308] Noise, vent (acoustic)'. Vent noise in the present document refers to noise which is generated by the flow of air through any vents such as vent holes of the patient interface.

[0309] Oxygen enriched air '. Air with a concentration of oxygen greater than that of atmospheric air (21%), for example at least about 50% oxygen, at least about 60% oxygen, at least about 70% oxygen, at least about 80% oxygen, at least about 90% oxygen, at least about 95% oxygen, at least about 98% oxygen, or at least about 99% oxygen. “Oxygen enriched air” is sometimes shortened to “oxygen”.

[0310] Medical Oxygen'. Medical oxygen is defined as oxygen enriched air with an oxygen concentration of 80% or greater.

[0311] Patient'. A person, whether or not they are suffering from a respiratory condition.

[0312] Pressure: Force per unit area. Pressure may be expressed in a range of units, including cmFFO, g-f / cm2and hectopascal. 1 cmFFO is equal to 1 g-f / cm2and is approximately 0.98 hectopascal (1 hectopascal = 100 Pa = 100 N / m2= 1 millibar ~0.001 atm). In this specification, unless otherwise stated, pressure is given in units of cmlLO.

[0313] The pressure in the patient interface is given the symbol Pm, while the treatment pressure, which represents a target value to be achieved by the interface pressure Pm at the current instant of time, is given the symbol Pt.

[0314] Respiratory Pressure Therapy. The application of a supply of air to an entrance to the airways at a treatment pressure that is typically positive with respect to atmosphere.

[0315] Ventilator'. A mechanical device that provides pressure support to a patient to perform some or all of the work of breathing.5.10.1.1 Materials & their properties

[0316] Hardness'. Refers to durometer or indentation hardness, which is a material property measured by indentation of an indentor (e.g., as measured in accordance with ASTM D2240).• ‘Soft’ materials may include silicone or thermo-plastic elastomer (TPE), and may, e.g. readily deform under finger pressure.• ‘Hard’ materials may include polycarbonate, polypropylene, and may not e.g. readily deform under finger pressure.

[0317] 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.

[0318] Polycarbonate', a thermoplastic polymer of Bisphenol-A Carbonate.5.10.1.2 Mechanics

[0319] Axes: a. Neutral axis'. An axis in the cross-section of a beam or plate along which there are no longitudinal stresses or strains. b. Longitudinal axis'. An axis extending along the length of a shape. The axis generally passes through a center of the shape.c. Circumferential axis'. An axis oriented perpendicularly with respect to the longitudinal axis. The axis may be specifically present in pipes, tubes, cylinders, or similar shapes with a circular and / or elliptical cross section.

[0320] Deformation'. The process where the original geometry of a member changes when subjected to forces, e.g. a force in a direction with respect to an axis. The process may include stretching or compressing, bending and, twisting.

[0321] Elasticity '. The ability of a material to return to its original geometry after deformation.

[0322] Floppy structure or component: A structure or component that will change shape, e.g. bend, when caused to support its own weight, within a relatively short period of time such as 1 second.

[0323] Resilience'. Ability of a material to absorb energy when deformed elastically and to release the energy upon unloading.

[0324] Resilient'. Will release substantially all of the energy when unloaded. Includes e.g. certain silicones, and thermoplastic elastomers.

[0325] Rigid structure or component: A structure or component that will not substantially change shape when subject to the loads typically encountered in use. An example of such a use may be setting up and maintaining a patient interface in sealing relationship with an entrance to a patient's airways, e.g. at a load of approximately 20 to 30 cmH20 pressure.

[0326] As an example, an I-beam may comprise a different bending stiffness (resistance to a bending load) in a first direction in comparison to a second, orthogonal direction. In another example, a structure or component may be floppy in a first direction and rigid in a second direction.

[0327] Stiffness (or rigidity) of a structure or component: The ability of the structure or component to resist deformation in response to an applied load. The load may be a force or a moment, e.g. compression, tension, bending or torsion. The structure or component may offer different resistances in different directions. The inverse of stiffness is flexibility.

[0328] Viscous'. The ability of a material to resist flow.

[0329] Visco-elasticity : The ability of a material to display both elastic and viscous behaviour in deformation.

[0330] Yield. The situation when a material can no longer return back to its original geometry after deformation.5.10.1.3 Structural Elements

[0331] Compression member: A structural element that resists compression forces.

[0332] Elbow. An elbow is an example of a structure that directs an axis of flow of air travelling therethrough to change direction through an angle. In one form, the angle may be approximately 90 degrees. In another form, the angle may be more, or less than 90 degrees. The elbow may have an approximately circular cross-section. In another form the elbow may have an oval or a rectangular cross-section. In certain forms an elbow may be rotatable with respect to a mating component, e.g. about 360 degrees. In certain forms an elbow may be removable from a mating component, e.g. via a snap connection. In certain forms, an elbow may be assembled to a mating component via a one-time snap during manufacture, but not removable by a patient.

[0333] 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.

[0334] 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.

[0335] Tie (noun)'. A structure designed to resist tension.

[0336] Thin structures: a. Beams, i. A beam may be relatively long in one dimension compared to the other two dimensions such that the smaller dimensions are comparatively thin compared to the long dimension b. Membranes, i. Relatively long in two dimensions, with one thin dimension. Readily deforms in response to bending forces. Resists being stretched, (might also resist compression). c. Plates & Shellsi. These may be relatively long in two directions, with one thin dimension. They may have bending, tensile, and / or compressive stiffness.

[0337] Thick structures: Solids

[0338] Seal'. May be a noun form ("a seal") which refers to a structure, or a verb form (“to seal”) which refers to the effect. Two elements may be constructed and / or arranged to ‘seal’ or to effect ‘sealing’ therebetween without requiring a separate ‘seal’ element per se.

[0339] 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.

[0340] 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.

[0341] 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.

[0342] Swivel (noun) '. A subassembly of components configured to rotate about a common axis, preferably independently, preferably under low torque. In one form, the swivel may be constructed to rotate through an angle of at least 360 degrees. In another form, the swivel may be constructed to rotate through an angle less than 360 degrees. When used in the context of an air delivery conduit, the sub-assembly of components preferably comprises a matched pair of cylindrical conduits. There may be little or no leak flow of air from the swivel in use.5.10.2 Respiratory cycle

[0343] 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.

[0344] Breathing rate '. The rate of spontaneous respiration of a patient, usually measured in breaths per minute.

[0345] Duty cycle '. The ratio of inhalation time, Ti to total breath time, Ttot.

[0346] Effort (breathing): The work done by a spontaneously breathing person attempting to breathe.

[0347] Expiratory portion of a breathing cycle: The period from the start of expiratory flow to the start of inspiratory flow.

[0348] 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.

[0349] 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.

[0350] Efypopnea'. According to some definitions, a hypopnea is taken to be a reduction in flow, but not a cessation of flow. In one form, a hypopnea may be said to have occurred when there is a reduction in flow below a threshold rate for a duration. A central hypopnea will be said to have occurred when a hypopnea is detected that is due to a reduction in breathing effort. In one form in adults, either of the following may be regarded as being hypopneas:(i) a 30% reduction in patient breathing for at least 10 seconds plus an associated 4% desaturation; or(ii) a reduction in patient breathing (but less than 50%) for at least 10 seconds, with an associated desaturation of at least 3% or an arousal.

[0351] Hyperpnea'. An increase in flow to a level higher than normal.

[0352] 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.

[0353] 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).

[0354] Positive End-Expiratory Pressure (PEEP) : The pressure above atmosphere in the lungs that exists at the end of expiration.

[0355] Peak flow rate Qpeak . The maximum value of flow rate during the inspiratory portion of the respiratory flow waveform.

[0356] Respiratory flow rate, patient airflow rate, respiratory airflow rate (Qr)These terms may be understood to refer to the RPT device’s estimate of respiratory flow rate, as opposed to “true respiratory flow rate” or “true respiratory flow rate”, which is the actual respiratory flow rate experienced by the patient, usually expressed in litres per minute.

[0357] Tidal volume (Vt): The volume of air inhaled or exhaled during normal breathing, when extra effort is not applied. In principle the inspiratory volume Vi (the volume of air inhaled) is equal to the expiratory volume Ve (the volume of air exhaled), and therefore a single tidal volume Vt may be defined as equal to either quantity. In practice the tidal volume Vt is estimated as some combination, e.g. the mean, of the inspiratory volume Vi and the expiratory volume Ve.

[0358] Inhalation Time (Ti): The duration of the inspiratory portion of the respiratory flow rate waveform.

[0359] Exhalation Time (Ze): The duration of the expiratory portion of the respiratory flow rate waveform.

[0360] Total Time (Ttot): The total duration between the start of one inspiratory portion of a respiratory flow rate waveform and the start of the following inspiratory portion of the respiratory flow rate waveform.

[0361] Typical recent ventilation'. The value of ventilation around which recent values of ventilation Vent over some predetermined timescale tend to cluster, that is, a measure of the central tendency of the recent values of ventilation.

[0362] Upper airway obstruction (UAO) includes both partial and total upper airway obstruction. This may be associated with a state of flow limitation, in whichthe flow rate increases only slightly or may even decrease as the pressure difference across the upper airway increases (Starling resistor behaviour).

[0363] Ventilation (Vent): A measure of a rate of gas being exchanged by the patient’s respiratory system. Measures of ventilation may include one or both 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.5.10.3 Ventilation

[0364] 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.

[0365] 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.

[0366] Cycled: The termination of a ventilator's inspiratory phase. When a ventilator delivers a breath to a spontaneously breathing patient, at the end of the inspiratory portion of the breathing cycle, the ventilator is said to be cycled to stop delivering the breath.

[0367] Expiratory positive airway pressure (EPAP): a base pressure, to which a pressure varying within the breath is added to produce the desired interface pressure which the ventilator will attempt to achieve at a given time.

[0368] End expiratory pressure (EEP): Desired interface pressure which the ventilator will attempt to achieve at the end of the expiratory portion of the breath. If the pressure waveform template 11( ) is zero-valued at the end of expiration, i.e. 11(0) = 0 when = 1, the EEP is equal to the EPAP.

[0369] Inspiratory positive airway pressure (IPAP): Maximum desired interface pressure which the ventilator will attempt to achieve during the inspiratory portion of the breath.

[0370] Pressure support: A number that is indicative of the increase in pressure during ventilator inspiration over that during ventilator expiration, and generally means the difference in pressure between the maximum value during inspiration and the base pressure (e.g., PS = IPAP - EPAP). In some contexts, pressure supportmeans the difference which the ventilator aims to achieve, rather than what it actually achieves.

[0371] 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.

[0372] 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.

[0373] Swing: Equivalent term to pressure support.

[0374] Triggered: When a ventilator, or other respiratory therapy device such as an RPT device or portable oxygen concentrator, delivers a volume of breathable gas to a spontaneously breathing patient, it is said to be triggered to do so. Triggering usually takes place at or near the initiation of the respiratory portion of the breathing cycle by the patient's efforts.5.10.3.1 Anatomy of the respiratory system

[0375] 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.

[0376] Larynx: The larynx, or voice box houses the vocal folds and connects the inferior part of the pharynx (hypopharynx) with the trachea.

[0377] 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.

[0378] 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.

[0379] Pharynx: The part of the throat situated immediately inferior to (below) the nasal cavity, and superior to the oesophagus and larynx. The pharynx isconventionally 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).5.10.4 Patient interface

[0380] 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.

[0381] Headgear: Headgear will be taken to mean a form of positioning and stabilising structure designed to hold a device, e.g., a mask, on a head.

[0382] Plenum chamber: a mask plenum chamber will be taken to mean a portion of a patient interface having walls at least partially enclosing a volume of space, the volume having air therein pressurised above atmospheric pressure in use. A shell may form part of the walls of a mask plenum chamber.

[0383] Seal: May be a noun form ("a seal") which refers to a structure, or a verb form (“to seal”) which refers to the effect. Two elements may be constructed and / or arranged to ‘seal’ or to effect ‘sealing’ therebetween without requiring a separate ‘seal’ element per se.

[0384] Vent: (noun): A structure that allows a flow of air from an interior of the mask, or conduit, to ambient air for clinically effective washout of exhaled gases. For example, a clinically effective washout may involve a flow rate of about 10 litres per minute to about 100 litres per minute, depending on the mask design and treatment pressure.5.11 OTHER REMARKS

[0385] A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in Patent Office patent files or records, but otherwise reserves all copyright rights whatsoever.

[0386] Unless the context clearly dictates otherwise and where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit, between the upper and lower limit of that range, and any other stated or intervening value in that stated range is encompassed within the technology. The upper and lower limits of these intervening ranges, which may be independentlyincluded in the intervening ranges, are also encompassed within the technology, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the technology.

[0387] Furthermore, where a value or values are stated herein as being implemented as part of the technology, it is understood that such values may be approximated, unless otherwise stated, and such values may be utilized to any suitable significant digit to the extent that a practical technical implementation may permit or require it.

[0388] Furthermore, “approximately”, “substantially”, “about”, or any similar term used herein means + / - 5-10% of the recited value.

[0389] 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.

[0390] 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.

[0391] 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.

[0392] 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.

[0393] 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.

[0394] The subject headings used in the detailed description are included only for the ease of reference of the reader and should not be used to limit the subject matter found throughout the disclosure or the claims. The subject headings should not be used in construing the scope of the claims or the claim limitations.

[0395] 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.

[0396] 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.5.12 REFERENCE SIGNS LIST

Claims

6 CLAIMS1. A humidifier for a respiratory therapy apparatus comprising, an air passage for a gas to be humidified, the air passage having an inlet and outlet, a humidifier reservoir for containing a volume of water, a nozzle having an internal passage, wherein an inlet of the nozzle is in fluid communication with the humidifier reservoir, and an outlet of the nozzle is within the air passage, and the nozzle comprising a transducer, wherein the transducer is configured to change a volume of the internal passage of the nozzle, to thereby eject a water droplet from the nozzle outlet.

2. The humidifier of claim 1 wherein the nozzle is configured to direct the water droplet onto a surface of the air passage.

3. The humidifier of claim 1 or 2, wherein the transducer is a piezoelectric transducer.

4. The humidifier of claim 1, 2 or 3, wherein the transducer is provided to an external surface of the nozzle.

5. The humidifier of claim 1, 2 or 3, wherein the transducer is provided to an internal surface of the nozzle.

6. The humidifier of any one of claims 1 to 5, wherein the nozzle outlet has a diameter no more than 1mm.

7. A humidifier for a respiratory therapy apparatus comprising, an air passage for a gas to be humidified, the air passage having an inlet and outlet, a humidifier reservoir for containing a volume of water, a water outlet member in fluid communication with the humidifier reservoir, the water outlet member comprising a plurality of outlet apertures, each outlet aperture having a diameter of no more than 1mm, wherein the outlet apertures are within the air passage,the apparatus further comprising a transducer configured to increase a pressure of the water when activated, to thereby cause a volume of the water to pass through the outlet apertures into the air passage.

8. The humidifier of claim 7, wherein the transducer is provided within the humidifier reservoir.

9. The humidifier of claim 7, wherein water outlet member is connected to the humidifier reservoir by a conduit, and the transducer is provided within the conduit.

10. The humidifier of claim 7, 8 or 9 wherein the transducer is a piezoelectric transducer.

11. A humidifier for a respiratory therapy apparatus comprising, an air passage for a gas to be humidified, the air passage having an inlet and outlet, a humidifier reservoir for containing a volume of water, a water outlet member in fluid communication with the humidifier reservoir, the water outlet member comprising a plurality of outlet apertures, each outlet aperture having a diameter of no more than 1mm, wherein the outlet apertures are within the air passage, the apparatus further comprising a transducer configured to displace or deform the water outlet member when activated, to thereby cause a volume of the water to pass through the outlet apertures into the air passage.

12. The humidifier of claim 11, wherein the transducer is a piezoelectric transducer.

13. A humidifier for a respiratory therapy apparatus comprising, an air passage for a gas to be humidified, the air passage having an inlet and outlet, a humidifier reservoir for containing a volume of water,a wicking material provided within the air passage and in fluid communication with the humidifier reservoir, and a heating element in contact with the wicking material and configured to heat the water present in the wicking material.

14. The humidifier of claim 13, wherein the wicking material comprises one or more of fluted paper, woven textile, non-woven textile, open cell foam, woven mesh and / or metal mesh.

15. The humidifier of claim 13 or 14, wherein the wicking material surrounds the heating element.

16. A patient interface for treating a patient with a respiratory disorder, comprising: a respiratory pressure therapy (RPT) device including an electric blower configured to generate pressurized breathable air; a seal -forming structure configured to form a seal against the patient’s face, the seal-forming structure at least partially defining a plenum chamber configured to receive the pressurized air; a flow generator casing that at least partly encloses the electric blower and is connected to the plenum chamber, the flow generator casing including at least one air opening to receive ambient air for delivery to the RPT device; a humidifier according to any one of claims 1 to 15 provided to an air path between the flow generator and the plenum chamber; and a positioning and stabilising structure configured to maintain the sealforming structure and the blower in a therapeutically effective position.

17. The patient interface of claim 16, wherein the humidifier is depowered or switched off during at least part of the patient’s breathing cycle.

18. The patient interface of claim 17, wherein the humidifier is depowered or switched off during at least part of an exhalation phase of the patient's breathing cycle.

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