Tube detection system and method

Abstract

An apparatus can include a processing circuitry; a humidifier configured to humidify a breathable gas; an air delivery tube configured to convey the humidified breathable gas to a patient interface, the air delivery tube including a heating element, a sensor configured to measure a characteristic of the breathable gas, and a connector having a plurality of electrical tube contacts, at least a portion of which are coupled to the heating element and the sensor; and a contact assembly including a plurality of electrical apparatus contacts configured to electrically couple the plurality of electrical tube contacts to the processing circuitry. The processing circuitry can be configured to determine a type of air delivery tube coupled to the humidifier based on (1) which electrical apparatus contacts are coupled to the heating element and / or sensor, and / or (2) electrical characteristics measured via one or more electrical apparatus contacts.

Description

[0001] 1 CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application No. 62 / 868,674, filed June 28, 2019, which is incorporated herein by reference in its entirety. This application is related to U.S. Provisional Application No. 62 / 835,094, filed April 17, 2019, the contents of which are incorporated by reference herein in their entirety. 2 BACKGROUND 2.1 TECHNICAL FIELD

[0005] The present technology relates to one or more of screening, diagnosing, monitoring, treating, preventing, and ameliorating a respiratory-related disorder. The present technology also relates to medical devices or apparatuses and their use, and more specifically to methods and systems for identifying a type of device coupled to an apparatus configured to provide a flow of breathable gas (e.g., a type of air delivery tube).

[0006] 2.2 DESCRIPTION OF RELATED ART

[0007] 2.2.1 The Human Respiratory System and Its Disorders

[0008] The respiratory system of the body facilitates gas exchange. The nose and mouth form the entrance to the airways of the patient.

[0009] The airways include a sequence of branching tubes when the branching airways penetrate deeper into the lung, they become progressively narrower, shorter, and more numerous. The primary function of the lung is gas exchange, allowing oxygen to move from inhaled air to venous blood and carbon dioxide from venous blood to exhaled air. The trachea divides into the left and right principal bronchial tubes, which ultimately subdivide into terminal bronchioles. The bronchi constitute the conducting airways but do not participate in gas exchange. Further branching of the airways leads to the respiratory bronchioles, and ultimately to the alveoli. The alveolar region of the lung is where gas exchange occurs, and is called the respiratory zone. See, West, John B. Respiratory Physiology, 9thedition, Lippincott Williams & Wilkins, 2012.

[0010] There is a range of respiratory disorders. Certain disorders can be characterized by specific events, such as apneas, hypopneas, and hyperpneas.

[0011] 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.

[0012] Obstructive Sleep Apnea (OSA) is a form of Sleep Disordered Breathing (SDB) which involves partial or complete obstruction of the upper airway during sleep. It is caused by the combination of an abnormally small upper airway and muscle tone loss in the region of the tongue, soft palate and posterior oropharyngeal wall during sleep. The condition causes the affected patient to stop breathing for periods of time, typically between 30 seconds and 120 seconds, sometimes 200 to 300 times per night. This frequently results in excessive daytime sleepiness, and can cause cardiovascular disease and brain damage. The syndrome is common, particularly in middle aged overweight males, but the people affected can be unaware of the problem. See US Patent No. 4,944,310 (Sullivan).

[0013] Cheyne-Stokes Respiratory (CSR) is another form of Sleep Disordered Breathing. CSR is a disorder of the patient's respiratory controller where the rhythm of breathing becomes unstable and the patient's blood gases are unstable. CSR is characterised by alternating periods of hypopnoea (shallow breathing) and apnoea (breathing cessation) where the patient stops breathing. The respiratory effort can be violent and the patient can wake with a scream. The condition is treatable by Continuous Positive Airway Pressure (CPAP) or Variable Airway Pressure (VPAP) therapy.

[0014] Respiratory failure is an encompassing term for respiratory diseases where the lungs can't draw in enough oxygen or expel sufficient CO2 to meet the patient's needs. Respiratory failure can encompass some or all of the following conditions.

[0015] A patient with respiratory insufficiency, a form of respiratory failure, can experience abnormally short breath.

[0016] Obesity hypoventilation syndrome (OHS) is defined as the combination of severe obesity and chronic hypercapnoea in the presence of a normal awake PaC02, in the absence of other known causes of hypoventilation. Symptoms include breathlessness, morning headaches and excessive daytime sleepiness.

[0017] Chronic Obstructive Pulmonary Disease (COPD) encompasses any of a group of lower airway diseases that have certain characteristics in common. These include increased resistance to air movement, an extended expiratory phase of breathing, and loss of the normal elasticity of the lung. Examples of COPD are emphysema and chronic bronchitis. COPD is caused by chronic tobacco smoking (the primary risk factor), occupational exposures, air pollution, and genetic factors. Symptoms include laboured breathing, chronic cough and sputum production.

[0018] Neuromuscular Disease (NMD) is a broad term that encompasses many diseases and ailments that impair muscle function either directly by intrinsic muscle pathology, or indirectly by nerve pathology. Some NMD patients are characterised by progressive muscular impairment leading to loss of ambulation, being wheelchair-bound, dysphagia, respiratory muscle weakness, and, eventually, death from respiratory failure. Neuromuscular disorders can be divided into rapidly progressive and slowly progressive: (i) Rapidly progressive disorders: Characterised by muscle impairment that worsens over months, and leads to death within a few years (e.g. Amyotrophic lateral sclerosis (ALS) and Duchenne muscular dystrophy (DMD) in teenagers); (ii) Variable or slowly progressive disorders: Characterised by muscle impairment that worsens over years, and only mildly shortens life expectancy (e.g. Limb girdle, Facioscapulohumeral, and Myotonic muscular dystrophy). Symptoms of respiratory failure in NMD include: increasing generalised weakness, dysphagia, breathlessness during exercise and at rest, fatigue, sleepiness, morning headache, and difficulty concentrating and mood changes.

[0019] Chest wall disorders are a group of thoracic deformities that result in inefficient coupling of the respiratory muscles to the thoracic cage. These disorders are often characterised by a restrictive defect and share the potential for long term hypercapnic respiratory failure. Scoliosis and / or kyphoscoliosis can cause severe respiratory failure. Symptoms of respiratory failure include: breathlessness, peripheral oedema, orthopnea, repeated chest infections, morning headache, fatigue, poor sleep quality, and loss of appetite.

[0020] A range of therapies have been used to treat or ameliorate such conditions. Furthermore, such therapies can be utilised to prevent the development of respiratory distress in otherwise healthy individuals. However, these have a number of shortcomings.

[0021] 2.2.2 Treatment

[0022] A variety of respiratory therapies have been used to treat one or more of the above respiratory disorders, for example Continuous Positive Airway Pressure (CPAP) therapy, Non-invasive ventilation (NIV), Invasive ventilation (IV) and High Flow Therapy (HFT).

[0023] 2.2.2.1 Respiratory pressure therapy

[0024] Respiratory pressure therapy is the application of air supply to the entrance of the airways at a controlled target pressure that is nominally positive with respect to atmosphere throughout the patient’s respiratory cycle (as opposed to negative pressure therapies such as the tank respirator or cuirass).

[0025] 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 can 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 can be voluntary, and thus patients can elect not to comply with treatment if they find the devices used to provide such therapy to be any one or more of: uncomfortable, difficult to use, expensive, and aesthetically unappealing.

[0026] Non-invasive ventilation (NIV) provides ventilatory support to a patient through the upper airways, to assist the patient to breathe 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, such as OHS, COPD, NMD, and Chest Wall disorders. In some forms, the comfort and effectiveness of these therapies can be improved.

[0027] Invasive ventilation (IV) provides ventilatory support to a patient who is unable to breathe effectively on their own, and can be provided using an tracheostomy tube. In some forms, the comfort and effectiveness of these therapies can be improved.

[0028] 2.2.2.2 Flow therapies

[0029] Not all respiratory therapies aim to deliver a prescribed therapy pressure. Some respiratory therapies aim to deliver a prescribed respiratory volume by delivering an inspiratory flow rate profile over a target duration of time (possibly superimposed on a positive baseline pressure). In other cases, the interface to the patient’s airways is “open” (unsealed) and the respiratory therapy can supplement the patient’s own spontaneous breathing with a flow of conditioned or enriched gas. In one example, high flow therapy (HFT) is the delivery of a continuous, heated, humidified flow of air into the airways through an unsealed or “open” patient interface, at an “treatment flow rate” that is nominally set to exceed the peak inspiratory flow rate of the patient throughout the respiratory cycle. HFT has been used to treat OSA, CSR, respiratory failure, COPD, and other respiratory disorders. One mechanism of action is that the high flow of air at the airway entrance improves ventilation efficiency by flushing or washing out exhaled CO2 from the patient’s anatomic dead space. HFT is therefore sometimes referred to as deadspace therapy (DST). Other benefits can include elevated warmth and humidification (possibly beneficial to secretion management), and the potential for modest elevation of airway pressures. As an alternative to a constant flow, the treatment flow rate can follow a profile that varies with the respiratory cycle.

[0030] Another form of flow therapy is long-term oxygen therapy (LTOT) or supplemental oxygen therapy. A physician can prescribe a continuous flow of oxygen enriched gas to be delivered to the patient's airways at a specified oxygen concentration (from 21% of the fraction of oxygen in ambient air up to 100%) at a specified flow rate (e.g. 1 liter per minute (LPM), 2 LPM, 3 LPM, etc.). The flow rate can be constant or variable. The LTOT can be delivered via nasal prongs, a simple mask, or a hood.

[0031] 2.2.2.3 Supplemental oxygen

[0032] For some patients, oxygen therapy can be combined with respiratory pressure therapy or HFT by adding supplemental oxygen to the pressurised flow. When oxygen is added to respiratory pressure therapy, this is referred to as RPT with supplemental oxygen. When oxygen is added to HFT, the resulting therapy is referred to as HFT with supplemental oxygen.

[0033] 2.2.3 Respiratory therapy system

[0034] These respiratory therapies can be provided by a respiratory therapy system or device. Such systems and devices can also be used to screen for, diagnose, or monitor a condition without treating it.

[0035] A respiratory therapy system can include a respiratory pressure therapy device (RPT device), an air circuit, a humidifier, a patient interface, an oxygen source, and data management.

[0036] Another form of therapy system is a mandibular repositioning device.

[0037] 2.2.3.1 Patient interface

[0038] A patient interface can be used to interface a respiratory apparatus to its wearer, e.g., by providing a flow of air to an entrance to the airways. The flow of air can be provided via a mask to the nose and / or mouth, via a tube to the mouth, or via a tracheal tube to the trachea of a patient. Depending on the therapy to be applied, the patient interface can form a seal, e.g., with areas of the patient's face, to facilitate the delivery of gas at a pressure sufficiently different from ambient pressure (e.g., positive pressure of about 10 cmH20 relative to ambient pressure) to the airways to effect therapy. For other forms of therapy, such as the delivery of oxygen, the patient interface can not include a seal sufficient to facilitate delivery to the airways of a supply of gas at positive pressures of about 10 cmH20. For flow therapies such as nasal HFT, the patient interface is configured to blow gas into the nares, but specifically to avoid a full seal. One example of such a patient interface is a nasal hood.

[0039] Certain other mask systems can not be functionally suitable for use in the art. For example, purely decorative masks can not maintain an appropriate pressure. Mask systems used for underwater swimming or diving can be configured to prevent water from the higher pressure outside from entering, but will not maintain the air inside at a pressure higher than ambient.

[0040] Certain masks can be clinically disadvantageous for the present technology, for example if they obstruct airflow through the nose and only allow it through the mouth.

[0041] Certain masks can be uncomfortable or impractical for the present technology if the patient is required to insert a portion of the mask structure in their mouth to create and maintain a seal through their lips.

[0042] Certain masks can be impractical for use while sleeping, for example when lying on one's side in bed with the head on a pillow.

[0043] The design of patient interfaces presents a number of challenges. The face has a complex three-dimensional shape. The size and shape of the nose and head varies greatly between different individuals. As the head includes bone, cartilage, and soft tissue, different regions of the face respond differently to mechanical forces. The jaw or mandible can move relative to other bones of the skull. The entire head can move during respiratory therapy.

[0044] As a result of these challenges, some masks suffer from one or more of the problems of being protruding, aesthetically undesirable, expensive, ill-fitting, difficult to use, and uncomfortable, particularly when worn for long periods or when the patient is not familiar with the system. Masks that are incorrectly sized can result in reduced compliance, reduced comfort, and poorer patient outcomes. Masks designed only for pilots, masks designed as part of personal protection equipment (such as filtering masks), SCUBA masks, or masks for the administration of anaesthetics can be tolerable for their original application, but nonetheless such masks can be undesirably uncomfortable when worn for long periods of time (e.g. several hours). This discomfort can result in reduced patient compliance with therapy. This is even more so if the mask is worn during sleep.

[0045] CPAP therapy is highly effective for treating certain respiratory disorders, provided that the patient complies with the therapy. If the mask is uncomfortable or difficult to use, the patient can not comply with the therapy. Because it is generally recommended that patients clean their masks on a regular basis, if the mask is difficult to clean (e.g. difficult to assemble or disassemble), the patient can not clean their mask, and this can impact on the patient's compliance.

[0046] While masks for other applications (e.g. navigators) can not be suitable for treating sleep disordered breathing, masks designed for treating sleep disordered breathing can be suitable for other applications.

[0047] For these reasons, patient interfaces for delivering CPAP during sleep form a distinct field.

[0048] Respiratory pressure therapy (RPT) device

[0049] A respiratory pressure therapy (RPT) device can be used alone or as part of a system to deliver one or more of a number of therapies described above, for example by operating the device to generate a flow of air for delivery to an interface to the airways. The flow of air can be pressure controlled (for respiratory pressure therapy) or flow controlled (for flow therapy such as HFT). Thus, an RPT device can also be used as a flow therapy device. Examples of RPT devices include CPAP devices and ventilators.

[0050] Pneumatic generators are known in a variety of applications, for example industrial scale ventilation systems. However, pneumatic generators for medical applications have specific requirements that are not met by more general pneumatic generators, for example reliability, size and weight requirements of medical devices. Furthermore, even devices designed for medical therapy can have drawbacks related to one or more of: comfort, noise, ease of use, efficacy, size, weight, manufacturability, cost and reliability.

[0051] One example of a particular requirement for certain RPT devices is noise.

[0052] Table of noise output levels for existing RPT devices (only one sample, measured at 10 cmH20 in CPAP mode using the test method specified in ISO 3744).

[0053] RPT device name A-weighted sound pressure level dB(A) Year (approx.) C-Series Tango TM ]]> 31.9 2007 C-Series Tango with humidifier TM ]]> 33.1 2007 [SCAT S8 Escape TM II]] 30.5 2005 Having H4i TM S8 Escape of humidifier TM II]] 31.1 2005 [S9 AutoSet TM ]]> 26.5 2010 S9 AutoSet with H5i humidifier TM ]] 28.6 2010

[0054] One known RPT device for treating sleep disordered breathing is the S9 Sleep Therapy System, manufactured by ResMed Limited. Another example of an RPT device is a ventilator. The ResMed Stellar TM Series of ventilators, for example adult and paediatric ventilators, can provide invasive and non-invasive non-dependent ventilation support for a range of patients for the treatment of a number of conditions, for example but not limited to NMD, OHS and COPD.

[0055] ResMed Elisée TM 150 ventilator and ResMed VS III TM ResMed Stellar Series of ventilators can provide invasive and non-invasive dependent ventilation support for adult or paediatric patients for the treatment of a number of conditions. These ventilators provide volume and pressure ventilation modes with a single limb circuit or a dual limb circuit. RPT devices generally comprise a pressure generator, for example 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 can be supplied to the airway of a 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.

[0056] The designer of a device can 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 can be highly sensitive to small, subtle changes in one or more parameters.

[0057] 2.2.3.2 Air circuit

[0058] An air circuit is a conduit or tube constructed and arranged to allow, in use, a flow of air to travel between two components of a respiratory therapy system, such as an RPT device and a patient interface. In some cases, there can be separate limbs of the air circuit for inhalation and exhalation. In other cases, a single limb air circuit is used for inhalation and exhalation.

[0059] 2.2.3.3 Humidifier

[0060] Delivery of a flow of air without humidification can result in drying of the airways. The use of a humidifier with an RPT device and a patient interface produces humidified gas that minimizes drying of the nasal mucosa and increases patient airway comfort. Furthermore, in cooler climates, warm air applied into and around the face region of the patient interface is generally more comfortable than cold air. Thus, a humidifier generally has the capability to heat the flow of air as well as humidify the flow of air.

[0061] Many artificial humidification devices and systems are known, however they do not meet the special requirements of a medical humidifier.

[0062] Medical humidifiers are used when required to increase the humidity and / or temperature of a flow of air relative to ambient air, typically where the patient is sleeping or resting, for example in a hospital. Medical humidifiers for bedside placement can be small. A medical humidifier can 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. For example, a room-based system such as a sauna, air conditioner or evaporative cooler can also humidify the air inhaled by the patient, however these systems also humidify and / or heat the entire room, which can cause discomfort to the occupants. Furthermore, medical humidifiers can have more stringent safety constraints than industrial humidifiers.

[0063] While many medical humidifiers are known, they can have one or more shortcomings. Some medical humidifiers can provide inadequate humidification, some are difficult or inconvenient to use by patients.

[0064] 2.2.3.4 Oxygen source

[0065] Experts in the field have recognized that exercise for patients with respiratory failure provides long-term benefits that slow disease progression, improve quality of life, and extend the patient's life. However, most stationary forms of exercise such as treadmills and stationary bicycles are too strenuous for these patients. As a result, the need for mobility has long been recognized. Until recently, this mobility was facilitated by the use of small compressed oxygen tanks or cylinders mounted on carts with wheels. The disadvantage of these tanks is that they contain a limited amount of oxygen and are heavy, weighing about 50 pounds when mounted.

[0066] Oxygen concentrators have been used for about 50 years to provide oxygen for respiratory therapy. Conventional oxygen concentrators are large and bulky, making ordinary ambulatory activities difficult and impractical. Recently, companies that manufacture large stationary oxygen concentrators have begun to develop portable oxygen concentrators (POCs). The advantage of POCs is that they can produce theoretically unlimited supplies of oxygen. To make the mobility of these devices small, the various systems used to produce the oxygen-rich gas need to be condensed. POCs seek to use as efficiently as possible the oxygen they produce to minimize weight, size, and power consumption. This can be achieved by delivering the oxygen in a series of pulses or "boli," each timed to coincide with the start of inhalation. This mode of therapy is called pulsed or on-demand (oxygen) delivery (POD), as opposed to the more traditional continuous flow delivery that is better suited to stationary oxygen concentrators.

[0067] 2.2.3.5 Data management

[0068] There can be clinical reasons to obtain data to determine whether a patient prescribed 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 is required to use the RPT device for at least 4 hours on a single night for at least 21 of 30 consecutive days in order to be considered compliant. To determine a patient's compliance, a provider of the RPT device (e.g., a healthcare provider) can manually obtain data describing the patient's therapy using the RPT device, calculate the usage over the predetermined period of time, and compare to the compliance rule. Once the healthcare provider has determined that the patient has used their RPT device according to the compliance rule, the healthcare provider can notify a third party that the patient is compliant.

[0069] There can be other aspects of a patient's therapy that would benefit from communication from therapy data to a third party or external system.

[0070] Existing processes to communicate and manage such data can be one or more of expensive, time consuming, and error prone.

[0071] 2.2.3.6 Mandibular repositioning

[0072] A mandibular repositioning device (MRD) or mandibular advancement device (MAD) is one of the treatment options for sleep apnea and snoring. It is an adjustable oral appliance available from a dentist or other supplier that holds the mandible (lower jawbone) in a forward position during sleep. The MRD is a removable device that the patient inserts into their mouth before going to sleep and removes after sleeping. Thus, the MRD is not designed to be worn all the time. The MRD can be custom made or produced in a standard form and includes a bite impression portion designed to allow for the patient's teeth. This mechanical protrusion of the mandible expands the space behind the tongue, exerts tension on the pharyngeal walls to reduce collapse of the airway and reduces palate vibrations.

[0073] In certain examples, the mandibular advancement device can include an upper splint for engaging or fitting over the teeth of the maxilla or maxilla and a lower splint for engaging or fitting over the teeth of the maxilla or mandible. The upper and lower splints are laterally connected together by a pair of connecting links. The pair of connecting links are symmetrically fixed to the upper and lower splints.

[0074] In this design, the length of the connecting links is selected so that when the MRD is placed in the patient's mouth, the mandible is held in an advanced position. The length of the connecting links can be adjusted to change the level of protrusion of the mandible. The dentist can determine the level of protrusion of the mandible that will determine the length of the connecting links.

[0075] Some MRDs are constructed to push the mandible forward relative to the maxilla, while others MADs (e.g., ResMed Narval CC TM The MRD is designed to hold the mandible in an advanced position. The device also reduces or minimizes dental and temporomandibular joint (TMJ) side effects. Thus, it is configured to minimize or prevent any movement of one or more teeth.

[0076] 2.2.4 Screening, diagnosis and monitoring systems

[0077] Polysomnography (PSG) is a conventional system for diagnosing and monitoring cardiopulmonary disorders and typically involves a clinical expert to apply the system. PSG typically involves placing 15 to 20 contact sensors on a patient to record various body signals such as electroencephalogram (EEG), electrocardiogram (ECG), electrooculogram (EOG), electromyogram (EMG), etc. PSG for sleep disordered breathing involves observing the patient for two nights in a clinic, one night purely diagnostic and a second night for the clinician to titrate treatment parameters. PSG is thus expensive and inconvenient. In particular, it is not suitable for home screening / diagnosis / monitoring of sleep disordered breathing.

[0078] Screening and diagnosis generally describe the identification of a condition from signs and symptoms of the condition. Screening generally gives a true / false result indicating whether the patient's SDB is severe enough to warrant further investigation, whereas diagnosis can produce clinically actionable information. Screening and diagnosis tend to be one-time processes, whereas monitoring the progression of the condition can continue indefinitely. Some screening / diagnosis systems are suitable only for screening / diagnosis, whereas some can also be used for monitoring.

[0079] A clinical specialist can be able to adequately screen, diagnose, or monitor a patient from visual observation of PSG signals. However, there are situations in which a clinical specialist can not be available or a clinical specialist can not be affordable. Different clinical specialists can disagree on a patient's condition. Furthermore, a given clinical specialist can apply different criteria at different times. 3SUMMARY

[0081] The present technology is directed towards providing medical devices for screening, diagnosing, monitoring, ameliorating, treating or preventing a respiratory disorder, with one or more of improved comfort, cost, efficacy, ease of use, and manufacturability.

[0082] A first aspect of the present technology relates to apparatus for screening, diagnosing, monitoring, ameliorating, treating or preventing a respiratory disorder.

[0083] Another aspect of the present technology relates to methods for screening, diagnosing, monitoring, ameliorating, treating or preventing a respiratory disorder.

[0084] One aspect of certain forms of the present technology is to provide methods and / or apparatuses to improve patient compliance with respiratory therapy.

[0085] One form of the present technology includes identifying the type of air delivery tube connected to the apparatus, so that operation of the apparatus can be optimized for the identified air delivery tube.

[0086] Another aspect of the present technology relates to processing circuitry configured to identify the type of air delivery tube coupled to an apparatus for humidifying a flow of breathable gas based on electrical contacts of the apparatus being used by contacts of the air delivery tube.

[0087] Another aspect of the present technology relates to processing circuitry configured to identify the type of air delivery tube coupled to an apparatus for humidifying a flow of breathable gas based on measured properties of passive or active circuit components in the air delivery tube.

[0088] Another aspect of the present technology relates to processing circuitry configured to identify a type of air delivery tube coupled to a device for humidifying a flow of breathable gas based on a measured property of circuitry in the air delivery tube that is not part of sensing circuitry for measuring a temperature in the air delivery tube. The property of the circuitry can include a presence or absence of a resistance value on one or more electrical connections of the air delivery tube.

[0089] Another aspect of the present technology relates to a respiratory therapy device including processing circuitry configured to identify a type of air delivery tube coupled to a humidifier and / or flow generator of the device based on a measured property of circuitry of the air delivery tube that is not part of sensing circuitry for measuring a temperature in the air delivery tube. The property of the circuitry can include a presence or absence of a connection and / or resistance value on one or more electrical connections of the air delivery tube.

[0090] Another aspect of the present technology relates to a device including processing circuitry; a humidifier configured for humidifying a breathable gas; an air delivery tube configured for conveying the humidified breathable gas to a patient interface, the air delivery tube including a heating element, a sensor configured for measuring a property of the breathable gas, and a connector having a plurality of electrical tube contacts, at least a portion of which are coupled to the heating element and the sensor; and a contact assembly including a plurality of electrical device contacts configured to electrically couple the plurality of electrical tube contacts to the processing circuitry. The processing circuitry can be configured to determine a type of air delivery tube coupled to the humidifier based on (1) which electrical device contacts are coupled to the heating element and / or sensor, and / or (2) an electrical property measured via one or more electrical device contacts.

[0091] Another aspect of the present technology relates to a device for humidifying a flow of breathable gas, including: processing circuitry; a humidifier configured for humidifying a breathable gas; an air delivery tube configured for conveying the humidified breathable gas to a patient interface, the air delivery tube including one or more heating elements extending along at least a portion of a length of the air delivery tube, a sensor configured for measuring a property of the humidified breathable gas in the air delivery tube, and a connector having a plurality of electrical tube contacts; and a contact assembly including a plurality of electrical device contacts configured to electrically couple the plurality of electrical tube contacts to the processing circuitry, wherein the one or more heating elements and the sensor are coupled to the electrical tube contacts, and the electrical tube contacts are adapted to electrically engage only a portion of the electrical device contacts in an operational configuration of the device.

[0092] In examples of the foregoing aspects: (a) the processing circuitry can be configured to control operation of the one or more heating elements and the humidifier based on signals received from the sensor, and determine a type of air delivery tube coupled to the device based on which electrical device contacts of the contact assembly are coupled to the electrical tube contacts in the operating configuration of the device; (b) the processing circuitry can be configured to determine a type of air delivery tube coupled to the device based on which electrical device contacts of the contact assembly are coupled to the electrical tube contacts in the operating configuration of the device; (c) the processing circuitry can be configured to control operation of the one or more heating elements and / or the humidifier based on the determined type of air delivery tube; (d) the processing circuitry can be configured to determine a type of air delivery tube coupled to the device based on a lack of connection through one or more electrical device contacts to the heating elements and / or sensor; (e) the contact assembly can include only four electrical device contacts, a first pair of electrical device contacts configured to be electrically coupled to the one or more heating elements, and only one contact of a second pair of electrical device contacts configured to be electrically coupled to the sensor; (f) the processing circuitry can determine a type of air delivery tube coupled to the device based on which of the second pair of electrical device contacts is coupled to the sensor; (g) the contact assembly can include only four electrical device contacts, a first pair of electrical device contacts configured to be electrically coupled to the one or more heating elements, and the processing circuitry can be configured to determine that a first type of air delivery tube is coupled to the device when a first contact of a second pair of electrical device contacts is not coupled to the sensor, and determine that a second type of air delivery tube is coupled to the device when a second contact of the second pair of electrical device contacts is not coupled to the sensor; (h) the contact assembly can include only four electrical device contacts, and the air delivery tube can include only three electrical tube contacts configured to be coupled to the electrical device contacts; and / or (i) the processing circuitry can be configured to determine a type of air delivery tube coupled to the device based on which electrical device contact of the contact assembly is not coupled to the electrical tube contacts.

[0093] Another aspect of the present technology relates to an apparatus for humidifying a flow of breathable gas, comprising: processing circuitry; a humidifier configured for humidifying breathable gas; an air delivery tube configured to convey the humidified breathable gas to a patient interface, the air delivery tube comprising one or more heating elements extending along at least a portion of a length of the air delivery tube, a sensor configured to measure a property of the breathable gas in the air delivery tube, and a connector having a plurality of electrical tube contacts; and a contact assembly comprising a plurality of electrical device contacts configured to electrically couple the plurality of electrical tube contacts to the processing circuitry in an operational configuration of the apparatus, wherein the one or more heating elements and the sensor are coupled to a set of the electrical tube contacts configured to be electrically coupled to the corresponding electrical device contacts in the operational configuration of the apparatus, and the processing circuitry is configured to determine a type of air delivery tube coupled to the apparatus based on an electrical property measured by the processing circuitry via another electrical device contact of the contact assembly.

[0094] In examples of the foregoing aspects: (a) the processing circuitry can be configured to control operation of the one or more heating elements and the humidifier based on signals received from the sensor; (b) the measured property can comprise a voltage based on a resistance element disposed in the air delivery tube and coupled to the another electrical device contact and the electrical tube contact configured to be electrically coupled to the heating element; (c) the processing circuitry can be configured to determine that a first type of air delivery tube is coupled to the apparatus when the measured property indicates zero volts, and that a second type of air delivery tube is coupled to the apparatus when the measured property indicates a voltage greater than zero; (d) the air delivery tube can comprise a resistor or shunt coupled between a contact of the set of electrical tube contacts and the electrical tube contact configured to be electrically coupled to the another electrical device contact; (e) the processing circuitry can be configured to control operation of the one or more heating elements and the humidifier based on the determined type of air delivery tube; and / or (f) the contact assembly can comprise only four electrical device contacts, and the air delivery tube comprises only three electrical tube contacts configured to be coupled to the electrical device contacts.

[0095] Another aspect of the present technology relates to a respiratory treatment apparatus comprising: a power supply; a processing system; a pressure generator configured for generating a flow of breathable gas; a humidifier configured for storing a supply of water for humidifying the breathable gas and comprising a first heating element configured for heating the supply of water; an air delivery tube configured to deliver humidified breathable gas flow to a patient, the air delivery tube comprising a second heating element configured to heat the humidified breathable gas in the air delivery tube and a thermistor configured to generate a temperature signal representative of a temperature of the humidified breathable gas in the air delivery tube; a transducer configured for generating a flow signal representative of a characteristic of the flow of breathable gas; and a contact assembly configured to mechanically couple the air delivery tube to the humidifier and to electrically couple a plurality of main contacts coupled to the processing system to a plurality of tube contacts coupled to the second heating element and the thermistor, wherein in an operating configuration of the respiratory treatment apparatus only a portion of the main contacts are coupled to respective tube contacts. The processing system can be configured to: determine which main contact is coupled to the second heating element and the thermistor via the tube contacts based on signal values received from one or more of the main contacts; determine a type of air delivery tube coupled to the humidifier based on determining which main contact is coupled to the second heating element and the thermistor; and based on the determined tube type, the flow signal and the temperature signal, determine (1) a first control signal for controlling the first heating element, (2) a second control signal for controlling the second heating element, and (3) a third control signal for controlling the pressure generator.

[0096] In examples of the foregoing aspects: the contact assembly comprises two main contacts configured to electrically couple to two tube contacts coupled to the second heating element and two additional main contacts configured to couple to two additional tube contacts, only one of the two additional tube contacts being coupled to the thermistor, and the processing system is configured to determine a type of air delivery tube coupled to the humidifier based on which of the two additional main contacts is coupled to the thermistor via the tube contacts.

[0097] Another aspect of one form of the present technology is a patient interface that is molded or otherwise constructed to have a peripheral shape that is complementary to the peripheral shape of an intended wearer.

[0098] One aspect of one form of the present technology is a method of manufacturing an apparatus.

[0099] One aspect of certain forms of the present technology is a medical device that is easy to use, for example by a person without medical training, by a person with limited dexterity, vision, or by a person with limited experience in using this type of medical device.

[0100] One aspect of one form of the technology is a portable RPT device that can be carried by a person, for example, in the person’s home.

[0101] One aspect of one form of the technology is a patient interface that can be washed in a patient’s home, for example, in soapy water, without the need for specialised cleaning equipment. One aspect of one form of the technology is a humidifier tank that can be washed in a patient’s home, for example, in soapy water, without the need for specialised cleaning equipment.

[0102] The described methods, systems, devices and apparatus can be implemented to improve the functioning of processors, for example, processors of special purpose computers, respiratory monitors and / or respiratory treatment devices. Furthermore, the described methods, systems, devices and apparatus can provide improvements in the technical field of the automated management, monitoring and / or treatment of respiratory conditions including, for example, sleep disordered breathing.

[0103] Of course, some of these aspects can form sub-aspects of the technology. Furthermore, various aspects of the sub-aspects and / or aspects can be combined in various ways, and also form further aspects or sub-aspects of the technology.

[0104] Further features of the technology will become apparent from the following detailed description, abstract, drawings and claims. 4BRIEF DESCRIPTION OF DRAWINGS

[0106] The technology is illustrated in the accompanying drawings, which are depicted by way of example and not limitation, in which like references indicate similar elements, including:

[0107] 4.1 RESPIRATORY TREATMENT SYSTEM

[0108] Figure 1 A system is shown including a patient 1000 wearing a patient interface 3000 in the form of a 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 a humidified gas circuit 4170 to the patient 1000. A bed partner 1100 is also shown. The patient is sleeping in a supine sleeping position.

[0109] Figure 2 A system is shown including a patient 1000 wearing a patient interface 3000 in the form of a nasal mask receiving a supply of air at positive pressure from an RPT device 4000. Air from the RPT device is humidified in a humidifier 5000 and passes along a humidified gas circuit 4170 to the patient 1000.

[0110] Figure 3A system is shown comprising a patient 1000 wearing a patient interface 3000 in the form of a full-face mask receiving a supply of air at positive pressure from an RPT device 4000. Air from the RPT device is humidified in a humidifier 5000 and passes along an air circuit 4170 to the patient 1000. The patient is sleeping in a side sleeping position.

[0111] 4.2 RPT DEVICE

[0112] Figure 4A An RPT device according to one form of the present technology is shown.

[0113] Figure 4B is a schematic diagram of the pneumatic path of an RPT device according to one form of the present technology. The direction of upstream and downstream is indicated with reference to the blower and the patient interface. The blower is defined as being upstream of the patient interface and the patient interface is defined as being downstream of the blower, regardless of the actual direction of flow at any particular instant. Items located within the pneumatic path between the blower and the patient interface are downstream of the blower and upstream of the patient interface.

[0114] Figure 4C is a schematic diagram of the electrical components of an RPT device according to one form of the present technology.

[0115] Figure 4D is a schematic diagram of an algorithm implemented in an RPT device according to one form of the present technology.

[0116] Figure 4E is a flowchart showing a method performed by a therapy engine module of Figure 4D according to one form of the present technology.

[0117] 4.3 HUMIDIFIER

[0118] Figure 5A An isometric view of a humidifier according to one form of the present technology is shown.

[0119] Figure 5B An isometric view of a humidifier according to one form of the present technology is shown, showing a humidifier reservoir 5110 removed from a humidifier reservoir base 5130.

[0120] Figure 5C A schematic diagram of a humidifier according to one form of the present technology is shown.

[0121] 4.4 TUBE TYPE IDENTIFICATION

[0122] Figure 5D A schematic diagram of an air delivery tube comprising four wires connected to an RPT device according to one form of the present technology is shown.

[0123] Figure 5EA schematic of an air delivery tube comprising three lines connected to an RPT device is shown, in accordance with one form of the present technology.

[0124] Figure 5F A schematic of an air delivery tube comprising three lines connected to an RPT device is shown, in accordance with another form of the present technology.

[0125] Figure 5G A schematic of an air delivery tube connected to an RPT device is shown, in accordance with one form of the present technology, the RPT device comprising a detection line for identifying the tube type.

[0126] Figure 5H A schematic of an air delivery tube connected to an RPT device is shown, in accordance with one form of the present technology, the RPT device comprising a detection line for identifying the tube type.

[0127] Figure 5I An example heating tube detection circuit is shown, in accordance with one form of the present technology.

[0128] Figure 5J Another example heating tube detection circuit is shown, in accordance with one form of the present technology.

[0129] 4.5 Breathing waveforms

[0130] Figure 6A A model typical breathing waveform of a person while sleeping is shown.

[0131] Figure 6B Selected polysomnogram channels (pulse oximetry, flow, chest movement, and abdominal movement) of a patient during non-REM sleep breathing over a period of about ninety seconds under normal circumstances are shown.

[0132] Figure 6C A polysomnogram of a patient prior to treatment is shown.

[0133] Figure 6D Patient flow data is shown where the patient is experiencing a series of complete obstructive apneas.

[0134] Figure 6E A scaled inspiration portion of a breath is shown where the patient is experiencing low frequency inspiratory snoring.

[0135] Figure 6F A scaled inspiration portion of a breath is shown where the patient is experiencing an example of flattening inspiratory flow limitation.

[0136] Figure 6G A scaled inspiration portion of a breath is shown where the patient is experiencing an example of a "table top" flattening inspiratory flow limitation.

[0137] Figure 6HA scaled inspiration portion of respiration showing an example of a patient experiencing "panda ear" inspiratory flow limitation.

[0138] Figure 6I A scaled inspiration portion of respiration showing an example of a patient experiencing "chair" inspiratory flow limitation.

[0139] Figure 6J A scaled inspiration portion of respiration showing an example of a patient experiencing "reverse chair" inspiratory flow limitation.

[0140] Figure 6K A scaled inspiration portion of respiration showing an example of a patient experiencing "M-shaped" inspiratory flow limitation.

[0141] Figure 6L A scaled inspiration portion of respiration showing an example of a patient experiencing severe "M-shaped" inspiratory flow limitation.

[0142] Figure 6M Patient data from a patient with Cheyne-Stokes respiration is shown.

[0143] Figure 6N Patient data from another example of a patient with Cheyne-Stokes respiration using the same three channels as Figure 6M 5DETAILED DESCRIPTION

[0145] Before describing the present technology in further detail, it is to be understood that the technology is not limited to the specific examples described herein, which can vary. It is also to be understood that the terminology used herein is for the purpose of describing particular examples only and is not intended to be limiting.

[0146] The following description provides details of various examples which can share one or more common characteristics and / or features. It will be appreciated that one or more features of any one example can be combined with one or more features of another example or other examples. Additionally, any single feature or combination of features in any of the examples can constitute additional examples.

[0147] 5.1 TREATMENT

[0148] In one form, the technology includes a method for treating a respiratory disorder, the method including applying positive pressure to an entrance to the airways of a patient 1000.

[0149] In certain examples of the technology, an air supply at positive pressure is provided to the patient's nasal passages via one or both nares.

[0150] In certain examples of the technology, mouth breathing is limited, restricted or prevented.

[0151] 5.2 RESPIRATORY THERAPY SYSTEM​

[0152] In one form, the present technology comprises a respiratory therapy system for treating a respiratory disorder. The respiratory therapy system can comprise an RPT device 4000 for supplying a flow of air to a patient 1000 via an air circuit 4170 and a patient interface 3000 or 3800.

[0153] 5.3 Patient interface

[0154] A non-invasive patient interface 3000 according to an 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, a form of connection port 3600 for connection to an air circuit 4170, and a forehead support 3700. In some forms, a functional aspect can be provided by one or more physical components. In some forms, one physical component can provide one or more functional aspects. In use, the seal-forming structure 3100 is arranged to surround an entrance to a patient’s airways so as to maintain positive pressure at the entrance to the patient’s airways 1000. The sealed patient interface 3000 is thus suitable for delivery of positive airway pressure therapy.

[0155] A non-sealed patient interface 3800 in the form of a nasal cannula comprises nasal prongs 3810a, 3810b through which air can be delivered to respective nares of a patient 1000 via respective apertures in the tips of the prongs. Such nasal prongs typically do not form a seal with the inner or outer skin surfaces of the nares. Air can be delivered to the nasal prongs by one or more air supply lumens 3820a, 3820b coupled to the nasal cannula 3800. The lumens 3820a, 3820b lead from the nasal cannula 3800 to a respiratory therapy device via an air circuit. The non-sealed patient interface 3800 is particularly suitable for delivery of flow therapy, where the RPT device generates a flow of air at a controlled flow rate, rather than at a controlled pressure. The “vent” at the non-sealed patient interface 3800 is the passage to atmosphere via the patient’s nares between the ends of the prongs 3810a and 3810b of the cannula 3800, through which excess flow escapes to the ambient environment.

[0156] A patient interface can not be suitable for respiratory pressure therapy if it is not able to comfortably deliver a minimum level of positive pressure to the airways.

[0157] A patient interface 3000 according to one form of the present technology is constructed and arranged to be capable of supplying air at a positive pressure of at least 6 cmH20 relative to ambient.

[0158] A patient interface 3000 according to one form of the present technology is constructed and arranged to be capable of supplying air at a positive pressure of at least 10 cmH20 relative to ambient.

[0159] A patient interface 3000 according to an aspect of the present technology is constructed and arranged to be capable of supplying air at positive pressure of at least 20 cmH20 relative to ambient.

[0160] 5.4 RPT device

[0161] An RPT device 4000 according to an aspect of the present technology comprises mechanical, pneumatic, and / or electrical components and is configured to execute one or more algorithms 4300, for example any of the whole or part of the methods described herein. The RPT device 4000 can be configured to generate a flow of air for delivery to the airways of a patient, for example for treatment of one or more of the respiratory conditions described elsewhere in this document.

[0162] In one form, the RPT device 4000 is constructed and arranged to be capable of delivering a flow of air in the range -20 L / min to +150 L / min while maintaining a positive pressure of at least 6 cmH20, or at least 10 cmH20, or at least 20 cmH20.

[0163] The RPT device can have an outer casing 4010 which is formed in two parts: an upper portion 4012 and a lower portion 4014. Further, the outer casing 4010 can comprise one or more panels 4015. The RPT device 4000 comprises a chassis 4016 which supports one or more internal components of the RPT device 4000. The RPT device 4000 can comprise a handle 4018.

[0164] The pneumatic path of the RPT device 4000 can comprise one or more air path articles, for example an inlet air filter 4112, an inlet silencer 4122, a pressure generator 4140 (e.g. a blower 4142) capable of supplying air at positive pressure, an outlet silencer 4124, and one or more transducers 4270 such as a pressure sensor 4272 and a flow sensor 4274.

[0165] One or more air path articles can be located within a removable unitary structure which will be referred to as a pneumatic block 4020. The pneumatic block 4020 can be located within the outer casing 4010. In one form, the pneumatic block 4020 is supported by, or formed as part of, the chassis 4016.

[0166] The RPT device 4000 can have a 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, a memory 4260, a transducer 4270, a data communication interface 4280, and one or more output devices 4290. The electrical components 4200 can be mounted on a single printed circuit board assembly (PCBA) 4202. In an alternative form, the RPT device 4000 can comprise more than one PCBA 4202.

[0167] 5.4.1 RPT device mechanical & pneumatic components

[0168] An RPT device can comprise one or more of the following components in one integral unit. In an alternative form, one or more of the following components can be located as respective standalone units.

[0169] 5.4.1.1 Air filter

[0170] An RPT device according to one form of the present technology can comprise one air filter 4110, or a plurality of air filters 4110.

[0171] In one form, an inlet air filter 4112 is located at the start of the pneumatic path upstream of the pressure generator 4140.

[0172] In one form, an outlet air filter 4114, for example an anti-bacterial filter, is positioned between the outlet of the pneumatic block 4020 and the patient interface 3000 or 3800.

[0173] 5.4.1.2 Silencer

[0174] An RPT device according to one form of the present technology can comprise one silencer 4120, or a plurality of silencers 4120.

[0175] In one form of the present technology, an inlet silencer 4122 is located in the pneumatic path upstream of the pressure generator 4140.

[0176] In one form of the present technology, an outlet silencer 4124 is located in the pneumatic path between the pressure generator 4140 and the patient interface 3000 or 3800.

[0177] 5.4.1.3 Pressure generator

[0178] In one form of the present technology, the pressure generator 4140 for generating a flow or supply of air at positive pressure is a controllable blower 4142. The blower 4142 may, for example, include a brushless DC motor 4144 with one or more impellers. The impeller(s) can be located in a volute. The blower is capable of delivering a supply of air, for example, at rates up to about 120 litres / minute, at positive pressures in a range of about 4 cmH20 to about 20 cmH20, or other forms in delivery of a respiratory pressure therapy at up to about 30 cmH20. The blower can be as described in any one of the following patents or patent applications, the contents of which are incorporated by reference in their entirety: US Patent No. 7,866,944; US Patent No. 8,638,014; US Patent No. 8,636,479; and PCT Patent Application Publication No. WO 2013 / 020167.

[0179] The pressure generator 4140 is under the control of the therapy device controller 4240.

[0180] In other forms, the pressure generator 4140 can be a piston-driven pump, a pressure regulator connected to a high pressure source (for example, a compressed air reservoir), or a bellows.

[0181] 5.4.1.4 Transducers

[0182] The transducers can be internal to the RPT device, or external to the RPT device. External transducers can be located on or form part of, for example, an air circuit (for example, a patient interface). External transducers can be in the form of non-contact sensors, for example, Doppler radar motion sensors that transmit or transfer data to the RPT device.

[0183] In one form of the present technology, one or more transducers 4270 are located upstream and / or downstream of the pressure generator 4140. The one or more transducers 4270 can be constructed and arranged to generate a signal representative of a property of the flow of air (for example, flow, pressure or temperature) at the point in the pneumatic path.

[0184] In one form of the present technology, one or more transducers 4270 can be located in the vicinity of the patient interface 3000 or 3800.

[0185] In one form, signals from the transducers 4270 can be filtered, such as by low pass, high pass or band pass filtering.

[0186] 5.4.1.4.1 Flow sensors

[0187] Flow sensors 4274 according to the present technology can be based on differential pressure transducers, for example, SDP600 series differential pressure transducers from SENSIRION.

[0188] In one form, the signal generated by the flow sensor 4274 and indicative of flow is received by the central controller 4230.

[0189] 5.4.1.4.2 Pressure sensor

[0190] The pressure sensor 4272 according to the present technology is positioned in fluid communication with the pneumatic path. An example of a suitable pressure sensor is a transducer from the HONEYWELL ASDX series. Another suitable pressure sensor is a transducer from the NPA series from GENERAL ELECTRIC.

[0191] In one form, the signal generated by the pressure sensor 4272 is received by the central controller 4230.

[0192] 5.4.1.4.3 Motor speed transducer

[0193] In one form of the present technology, a motor speed transducer 4276 is used to determine the rotational speed of the motor 4144 and / or the blower 4142. The motor speed signal from the motor speed transducer 4276 can be provided to the therapy device controller 4240. The motor speed transducer 4276 may, for example, be a speed sensor such as a Hall effect sensor.

[0194] 5.4.1.5 Anti-overflow back valve

[0195] In one form of the present technology, an anti-overflow back valve 4160 is positioned between the humidifier 5000 and the pneumatic block 4020. The anti-overflow back valve is constructed and arranged to reduce the risk of water flowing upstream from the humidifier 5000 to, for example, the motor 4144.

[0196] 5.4.2 Electrical components of an RPT device

[0197] 5.4.2.1 Power supply

[0198] The power supply 4210 can be located inside or outside the housing 4010 of the RPT device 4000.

[0199] In one form of the present technology, the power supply 4210 provides power to the RPT device 4000 only. In another form of the present technology, the power supply 4210 provides power to both the RPT device 4000 and the humidifier 5000.

[0200] 5.4.2.2 Input device

[0201] In one form of the technology, the 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 can be physical devices or software devices accessible through a touch screen. The buttons, switches or dials can be physically connected to the housing 4010 in one form or can wirelessly communicate with a receiver electrically connected to the central controller 4230 in another form.

[0202] In one form, the input devices 4220 can be constructed and arranged to allow a person to select values and / or menu options.

[0203] 5.4.2.3 Central controller

[0204] In one form of the technology, the central controller 4230 is one or more processors adapted to control the RPT device 4000.

[0205] Suitable processors can include x86 INTEL processors, ARM Holdings based processors such as the CORTEX-M series of microcontrollers from ARM HOLDINGS PLC, or processors based on the MIPS instruction set such as the - processors based on the MIP S instruction set such as the STR9 series of microcontrollers from ST MICROELECTRONICS. In certain alternative forms of the technology, a 32-bit RISC CPU (such as the STR9 series of microcontrollers from ST MICROELECTRONICS) or a 16-bit RISC CPU (such as the processors of the MSP430 series of microcontrollers manufactured by TEXAS INSTRUMENTS) can also be suitable.

[0206] In one form of the technology, the central controller 4230 is a dedicated electronic circuit.

[0207] In one form, the central controller 4230 is an application specific integrated circuit. In another form, the central controller 4230 comprises discrete electronic components.

[0208] The central controller 4230 can be configured to receive input signals from the one or more transducers 4270, the one or more input devices 4220, and the humidifier 5000.

[0209] The central controller 4230 can be configured to provide output signals to one or more of the output devices 4290, the therapy device controller 4240, the data communication interface 4280, and the humidifier 5000.

[0210] In some forms of the technology, the central controller 4230 is configured to implement one or more methods described herein, for example one or more algorithms 4300 represented as computer programs stored in a non-transitory computer readable storage medium, such as the memory 4260. In some forms of the technology, the central controller 4230 can be integrated with the RPT device 4000. However, in some forms of the technology, some methods can be performed by a remotely located device. For example, a remotely located device can determine control settings for a ventilator or detect a respiratory related event by analysing stored data, such as from any of the sensors described herein.

[0211] 5.4.2.4 Clock

[0212] The RPT device 4000 can include a clock 4232 connected to the central controller 4230.

[0213] 5.4.2.5 Therapy device controller

[0214] In one form of the technology, the therapy device controller 4240 is a therapy control module 4330 which forms part of the algorithm 4300 executed by the central controller 4230.

[0215] In one form of the technology, the therapy device controller 4240 is a dedicated motor control integrated circuit. For example, in one form, an MC33035 brushless DC motor controller manufactured by ONSEMI is used.

[0216] 5.4.2.6 Protection circuitry

[0217] One or more protection circuitries 4250 according to the technology can include electrical protection circuitry, temperature and / or pressure safety circuitry.

[0218] 5.4.2.7 Memory

[0219] According to one form of the technology, the RPT device 4000 includes a memory 4260, such as a non-volatile memory. In some forms, the memory 4260 can include a battery backed-up static RAM. In some forms, the memory 4260 can include a volatile RAM.

[0220] The memory 4260 can be located on the PCBA 4202. The memory 4260 can be in the form of an EEPROM or a NAND flash memory.

[0221] Additionally or alternatively, the RPT device 4000 includes a memory 4260 in removable form, such as a memory card manufactured according to the Secure Digital (SD) standard.

[0222] In one form of the technology, the memory 4260 acts as a non-transitory computer readable storage medium having stored thereon computer program instructions which represent one or more methods described herein, such as one or more algorithms 4300.

[0223] 5.4.2.8 Data communication system

[0224] In one form of the technology, a data communication interface 4280 is provided which is connected to the central controller 4230. The data communication interface 4280 can be connected to a remote external communication network 4282 and / or a local external communication network 4284. The remote external communication network 4282 can be connected to a remote external device 4286. The local external communication network 4284 can be connected to a local external device 4288.

[0225] In one form, the data communication interface 4280 is part of the central controller 4230. In another form, the data communication interface 4280 is separate from the central controller 4230 and can comprise an integrated circuit or processor.

[0226] In one form, the remote external communication network 4282 is the Internet. The data communication interface 4280 can connect to the Internet using wired communication (e.g. via Ethernet or optical fibre) or wireless protocols (e.g. CDMA, GSM, LTE).

[0227] In one form, the local external communication network 4284 utilises one or more communication standards, such as Bluetooth or the consumer infrared protocol.

[0228] In one form, the remote external device 4286 is one or more computers, such as a cluster of networked computers. In one form, the remote external device 4286 can be a virtual computer, rather than a physical computer. In either case, such a remote external device 4286 can be accessible to a suitably authorised person, such as a clinician.

[0229] The local external device 4288 can be a personal computer, mobile phone, tablet or remote control device.

[0230] 5.4.2.9 Output device including optional display, alarm

[0231] The output device 4290 according to the technology can take the form of one or more of a visual, audio and tactile unit. The visual display can be a liquid crystal display (LCD) or light emitting diode (LED) display.

[0232] 5.4.2.9.1 Display driver

[0233] The display driver 4292 receives as input characters, symbols, or images to be displayed on the display 4294 and converts them into commands that cause the display 4294 to display the characters, symbols, or images.

[0234] 5.4.2.9.2 Display

[0235] The 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 can be an eight-segment display, in which case the display driver 4292 converts each character or symbol (e.g., the figure “0”) into 8 logic signals that indicate whether the 8 corresponding segments are to be activated to display the particular character or symbol.

[0236] 5.4.3 RPT device algorithms

[0237] As described above, in some forms of the technology the central controller 4230 can be configured to implement one or more algorithms 4300 represented as computer programs stored in a non-transitory computer-readable storage medium, such as the memory 4260. The algorithms 4300 are generally grouped into sets called modules.

[0238] In other forms of the technology some or all of the algorithms 4300 can be implemented by the controller of an external device, such as the local external device 4288 or the remote external device 4286. In such forms, the data representing the input signals and / or intermediate algorithm outputs required by the part of the algorithm 4300 to be executed at the external device can be communicated to the external device via the local external communications network 4284 or the remote external communications network 4282. In such forms, the part of the algorithm 4300 to be executed at the external device can be represented as a computer program stored in a non-transitory computer-readable storage medium accessible to the controller of the external device. Such a program configures the controller of the external device to perform the part of the algorithm 4300.

[0239] In such forms, treatment parameters generated by the external device via the therapy engine module 4320 (if that forms part of the part of the algorithm 4300 executed by the external device) can be communicated to the central controller 4230 to be passed to the therapy control module 4330.

[0240] 5.4.3.1 Pre-processing module

[0241] A pre-processing module 4310 according to one form of the technology receives as input signals from the transducer 4270 (e.g., the flow sensor 4274 or the pressure sensor 4272) and performs one or more processing steps to calculate one or more output values to be used as input to another module (e.g., the therapy engine module 4320).

[0242] In one form of the present technology, the output values include the interface pressure Pm, the respiratory flow rate Qr, and the leak flow rate Ql.

[0243] In various forms of the present technology, the pre-processing module 4310 includes one or more of the following algorithms: an interface pressure estimation 4312, a ventilation flow estimation 4314, a leak flow estimation 4316, and a respiratory flow estimation 4318.

[0244] 5.4.3.1.1 Interface pressure estimation

[0245] In one form of the present technology, the interface pressure estimation algorithm 4312 receives as inputs a signal from the pressure sensor 4272 indicative of the pressure in the pneumatic path adjacent the outlet of the pneumatic block (device pressure Pd) and a signal from the flow sensor 4274 representative of the flow of gas leaving the RPT device 4000 (device flow rate Qd). In the absence of any supplemental gas 4180, the device flow rate Qd can be used as the total flow rate Qt. The interface pressure algorithm 4312 estimates the pressure drop ΔΡ through the air circuit 4170. The dependence of the pressure drop ΔΡ on the total flow rate Qt can be modelled by a pressure drop characteristic ΔΡ(Ο) for the particular air circuit 4170. The interface pressure estimation algorithm 4312 then provides as an output an estimated pressure Pm in the patient interface 3000 or 3800. The pressure Pm in the patient interface 3000 or 3800 can be estimated as the device pressure Pd minus the air circuit pressure drop ΔΡ.

[0246] 5.4.3.1.2 Ventilation flow estimation

[0247] In one form of the present technology, the ventilation flow estimation algorithm 4314 receives as an input the estimated pressure Pm in the patient interface 3000 or 3800 from the interface pressure estimation algorithm 4312 and estimates the ventilation flow rate Qv of air from the vent 3400 in the patient interface 3000 or 3800. For a particular vent 3400 in use, the dependence of the vent flow rate Qv on the interface pressure Pm can be modelled by a vent characteristic Qv(Pm).

[0248] 5.4.3.1.3 Leak flow estimation

[0249] In one form of the present technology, the leak flow estimation algorithm 4316 receives as inputs the total flow rate Qt and the ventilation flow rate Qv and provides as an output an estimate of the leak flow rate Ql. In one form, the leak flow estimation algorithm estimates the leak flow rate Ql by calculating the average of the difference between the total flow rate Qt and the ventilation flow rate Qv over a sufficiently long period of time (e.g. about 10 seconds).

[0250] In one form, the leak flow estimation algorithm 4316 receives as inputs the total flow Qt, the ventilation flow Qv, and the estimated pressure Pm in the patient interface 3000 or 3800, and provides as an output the leak flow Ql by calculating a leak conductance and determining the leak flow Ql as a function of the leak conductance and the pressure Pm. The leak conductance is calculated as the quotient of a low pass filtered non-ventilation flow equal to the difference between the total flow Qt and the ventilation flow Qv, and a low pass filtered pressure square root Pm, with the low pass filter time constant having a value long enough to include several breath cycles, for example approximately 10 seconds. The leak flow Ql can be estimated as the product of the leak conductance and the pressure Pm as a function.

[0251] 5.4.3.1.4 Breathing flow estimation

[0252] In one form of the present technology, the breathing flow estimation algorithm 4318 receives as inputs the total flow Qt, the ventilation flow Qv, and the leak flow Ql, and estimates the breathing flow Qr of air to the patient by subtracting the ventilation flow Qv and the leak flow Ql from the total flow Qt.

[0253] 5.4.3.2 Therapy engine module

[0254] In one form of the present technology, the therapy engine module 4320 receives as inputs one or more of the pressure Pm in the patient interface 3000 or 3800 and the breathing flow Qr of air to the patient, and provides as an output one or more therapy parameters.

[0255] In one form of the present technology, the therapy parameter is a therapy pressure Pt.

[0256] In one form of the present technology, the therapy parameter is one or more of a pressure variation amplitude, a base pressure, and a target ventilation.

[0257] In various forms, the therapy engine module 4320 includes one or more of the following algorithms: phase determination 4321, waveform determination 4322, ventilation determination 4323, inspiratory flow limitation determination 4324, apnoea / hypopnoea determination 4325, snoring determination 4326, airway patency determination 4327, target ventilation determination 4328, and therapy parameter determination 4329.

[0258] 5.4.3.2.1 Phase determination

[0259] In one form of the present technology, the RPT device 4000 does not determine a phase.

[0260] In one form of the technology, the phase determination algorithm 4321 receives as input a signal indicative of respiratory flow rate Qr and provides as output the phase Φ of the current respiratory cycle of the patient 1000.

[0261] In some forms, known as discrete phase determination, the phase output Φ is a discrete variable. One implementation of discrete phase determination provides a two-valued phase output Φ with an inspiratory or expiratory value at the detection of the start of a spontaneous inspiration and expiration, respectively, for example values denoted as 0 and 0.5 turns, respectively. The RPT device 4000 is effectively performing discrete phase determination as the trigger point and cycle point are the times at which the phase changes from expiratory to inspiratory and from inspiratory to expiratory, respectively. In one implementation of two-valued phase determination, the phase output Φ is determined to have the discrete value 0 when the respiratory flow rate Qr has a value that exceeds a positive threshold (thereby “triggering” the RPT device 4000), and the phase output Φ is determined to have the discrete value 0.5 turns when the respiratory flow rate Qr has a value that is more negative than a negative threshold (thereby “cycling” the RPT device 4000). The inspiratory time Ti and expiratory time Te can be estimated as typical values over a number of respiratory cycles of the time taken for the phase Φ to equal 0 (indicating inspiration) and 0.5 (indicating expiration), respectively.

[0262] Another implementation of discrete phase determination provides a three-valued phase output Φ with a value of one of inspiratory, intermediate inspiratory pause, and expiratory.

[0263] In other forms, known as continuous phase determination, the phase output Φ is a continuous variable, for example varying from 0 to 1 turn, or 0 to 2p radians. An RPT device 4000 performing continuous phase determination can trigger and cycle when the continuous phase reaches 0 and 0.5 turns, respectively. In one implementation of continuous phase determination, a fuzzy logic analysis of the respiratory flow rate Qr is used to determine a continuous value of the phase Φ. The continuous value of the phase determined in this implementation is often referred to as a “fuzzy phase”. In one implementation of the fuzzy phase determination algorithm 4321, the following rules are applied to the respiratory flow rate Qr:

[0264] 1. If the respiratory flow rate is zero and rapidly increasing, the phase is 0 turns.

[0265] 2. If the respiratory flow rate is large and positive and stable, the phase is 0.25 turns.

[0266] 3. If the respiratory flow rate is zero and rapidly decreasing, the phase is 0.5 turns.

[0267] 4. If the respiratory flow rate is large and negative and stable, the phase is 0.75 turns.

[0268] 5. If the respiratory flow rate is zero and stable, and the 5 second low pass filtered absolute value of the respiratory flow rate is large, the phase is 0.9 turns.

[0269] 6. If respiratory flow is positive, phase is expiration, then phase is 0 turns.

[0270] 7. If respiratory flow is negative, phase is inspiration, then phase is 0.5 turns.

[0271] 8. If the 5-second low-pass filtered absolute value of respiratory flow is large, then phase is increased at a steady rate equal to the patient's respiratory rate, low-pass filtered with a time constant of 20 seconds.

[0272] The output of each rule can be represented as a vector whose phase is the result of the rule and whose magnitude is the degree of fuzziness with which the rule is true. The degree of fuzziness of respiratory flow being "large", "steady", etc. is determined with an appropriate membership function. The results of the rules are represented as vectors, which are then combined by some function such as taking the centroid. In such a combination, the rules can be weighted equally, differently.

[0273] In another implementation of continuous phase determination, the phase Φ is first discretely estimated from respiratory flow Qr as described above, as are the inspiration time Ti and the expiration time Te. The continuous phase Φ at any instant can be determined as half the proportion of inspiration time Ti that has elapsed since the previous triggering instant, or 0.5 turns plus half the proportion of expiration time Te that has elapsed since the previous cycle instant, whichever is more recent.

[0274] 5.4.3.2.2 Waveform determination

[0275] In one form of the technology, the therapy parameter determination algorithm 4329 provides an approximately constant therapy pressure throughout the respiratory cycle of the patient.

[0276] In other forms of the technology, the therapy control module 4330 controls the pressure generator 4140 to provide a therapy pressure Pt that varies as a function of phase Φ of the respiratory cycle of the patient according to a waveform template Π(Φ).

[0277] In one form of the technology, the waveform determination algorithm 4322 provides a waveform template Π(Φ) of values in the range [0, 1] over the phase values Φ provided by the phase determination algorithm 4321 for use by the therapy parameter determination algorithm 4329.

[0278] In one form suitable for discrete or continuous value phase, the waveform template Π(Φ) is a square wave template having a value of 1 for phase values up to and including 0.5 turns, and a value of 0 for phase values greater than 0.5 turns. In one form suitable for continuous value phase, the waveform template Π(Φ) comprises two smoothly curved portions, namely a smoothly curved (e.g. raised cosine) ramp up from 0 to 1 for phase values up to 0.5 turns, and a smoothly curved (e.g. exponential) decay from 1 to 0 for phase values greater than 0.5 turns. In one form suitable for continuous value phase, the waveform template Π(Φ) is based on a square wave, but smoothly ramps up from 0 to 1 for phase values up to a “ramp up time” less than 0.5 turns, and smoothly ramps down from 1 to 0 for phase values after 0.5 turns for a “ramp down time” less than 0.5 turns.

[0279] In some forms of the technology, the waveform determination algorithm 4322 selects a waveform template Π(Φ) from a library of waveform templates according to settings of the RPT device. Each waveform template Π(Φ) in the library can be provided as a lookup table of values Π against phase values Φ. In other forms, the waveform determination algorithm 4322 calculates the waveform template Π(Φ) “on the fly” using a predetermined functional form that can be parameterized by one or more parameters (e.g. time constant of an exponential curved portion). The parameters of the functional form can be predetermined or dependent on the current state of the patient 1000.

[0280] In some forms of the technology, suitable for discrete binary phase for inhalation (Φ = 0 turns) or exhalation (Φ = 0.5 turns), the waveform determination algorithm 4322 calculates the waveform template Π “on the fly” according to the discrete phase Φ and the time t measured from the most recent trigger instant. In one such form, the waveform determination algorithm 4322 calculates the waveform template Π(Φ, t) in two portions (inspiration and expiration) as follows:

[0281]

[0282] where Π i (t) and Π e (t) are the inspiration and expiration portions of the waveform template Π(Φ, t). In one such form, the inspiration portion of the waveform template Π i (t) is a smooth ramp up from 0 to 1 parameterized by a ramp up time, and the expiration portion of the waveform template Π e (t) is a smooth ramp down from 1 to 0 parameterized by a ramp down time.

[0283] 5.4.3.2.3 Ventilation determination

[0284] In one form of the technology, the ventilation amount determination algorithm 4323 receives an input of respiratory flow rate Qr, and determines a measure indicative of the current patient ventilation Vent.

[0285] In some implementations, the ventilation determination algorithm 4323 determines a measure of ventilation Vent that is an estimate of the actual patient ventilation. One such implementation is to take half of the absolute value of the respiratory flow rate Qr, optionally filtered by a low pass filter such as a second order Bessel low pass filter with a corner frequency of 0.11 Hz.

[0286] In other implementations, the ventilation determination algorithm 4323 determines a measure of ventilation Vent that is approximately proportional to the actual patient ventilation. One such implementation estimates the peak respiratory flow rate Qpeak over the inspiratory portion of the cycle. This process and many other processes that involve sampling the respiratory flow rate Qr yield a measure that is approximately proportional to ventilation, provided that the flow rate waveform shape does not vary much (here, two breaths are considered to have similar shape when their flow rate waveforms, normalized in time and amplitude, are similar). Some simple examples include the median of the positive respiratory flow rate, the median of the absolute value of the respiratory flow rate, and the standard deviation of the flow rate. Any linear combination of arbitrary order statistics of the absolute value of the respiratory flow rate using positive coefficients, and even some using positive and negative coefficients, are approximately proportional to ventilation. Another example is the average of the respiratory flow rate in the middle K fraction (in time) of the inspiratory portion, where 0 < K < 1. If the flow rate shape is constant, there are an infinite number of measures that are exactly proportional to ventilation.

[0287] 5.4.3.2.4 Determination of Inspiratory Flow Limitation

[0288] In one form of the present technology, the central controller 4230 executes an inspiratory flow limitation determination algorithm 4324 for determining the degree of inspiratory flow limitation.

[0289] In one form, the inspiratory flow limitation determination algorithm 4324 receives as input the respiratory flow rate signal Qr and provides as output a measure of the degree to which the inspiratory portion of the breath exhibits inspiratory flow limitation.

[0290] 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 (e.g. 65) representative of time points are interpolated along the inspiratory flow rate-time curve of each breath by an interpolator. The curve described by the points is then scaled by a scalar to have a uniform length (duration / period) and a uniform area to remove the effects of varying breath rate and depth. The scaled breath is then compared in a comparator to a pre-stored template representing a normal unobstructed breath, similar to Figure 6AThe inspiratory portion of the breath is shown. At any time during inspiration from this template, breaths that deviate beyond a specified threshold (typically 1 scaling unit) are rejected, such as those due to coughing, sighing, swallowing, and belching, as determined by the test element. For non-rejected data, a moving average of the first such scaled point is computed by the central controller 4230 for the first few inspiratory events. This is repeated for a second such point, on the same inspiratory event, and so on. Thus, for example, 65 scaled data points are generated by the central controller 4230, and represent a moving average of the previous few inspiratory events (e.g., three events). The moving average of the continuously updated value of the (e.g., sixty-five) points is hereinafter referred to as "scaled flow", denoted Qs(t). Alternatively, a single inspiratory event can be used instead of a moving average.

[0291] From the scaled flow, two shape factors can be computed that are related to determining partial obstruction.

[0292] Shape factor 1 is the ratio of the average of the middle (e.g., 32) scaled flow points to the total average (e.g., 65) scaled flow points. When this ratio exceeds 1, the breath will be normal. When the ratio is 1 or less, the breath will be obstructed. A ratio of about 1.17 is taken as the threshold between partially obstructed and unobstructed breaths, and is equal to the degree of obstruction that allows sufficient oxygenation to be maintained in a typical patient.

[0293] Shape factor 2 is computed as the RMS deviation of the unit scaled flow over the middle (e.g., 32) points. An RMS deviation of about 0.2 units is considered normal. Zero RMS deviation is considered a fully flow-limited breath. The closer the RMS deviation is to zero, the more flow-limited the breath will be considered to be.

[0294] Shape factors 1 and 2 can be used as alternatives, or in combination. In other forms of the technology, the number of sampling points, breaths, and middle points can be different from those described above. In addition, the threshold values can be different from those described.

[0295] 5.4.3.2.5 Determination of Apnea and Hypopnea

[0296] In one form of the technology, the central controller 4230 executes an apnea / hypopnea determination algorithm 4325 for determining the presence of apnea and / or hypopnea.

[0297] In one form, the apnea / hypopnea determination algorithm 4325 receives as input the respiratory flow signal Qr, and provides as output a flag indicating that an apnea or hypopnea has been detected.

[0298] In one form, a respiratory pause will be deemed 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 can determine peak flow rate, a relatively short term average flow rate, or an intermediate flow rate between the relatively short term average and peak flow rate, such as RMS flow rate. The flow rate threshold can be a relatively long term measure of flow rate.

[0299] In one form, a respiratory insufficiency will be deemed 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 can determine peak flow rate, a relatively short term average flow rate, or an intermediate flow rate between the relatively short term average and peak flow rate, such as RMS flow rate. The second flow rate threshold can be a relatively long term measure of flow rate. The second flow rate threshold is greater than the flow rate threshold used to detect respiratory pause.

[0300] 5.4.3.2.6 Determination of snoring

[0301] In one form of the present technology, the central controller 4230 executes one or more snore determination algorithms 4326 for determining a degree of snoring.

[0302] In one form, the snore determination algorithm 4326 receives as input a respiratory flow rate signal Qr and provides as output a measure of the degree of occurrence of snoring.

[0303] The snore determination algorithm 4326 can include a step of determining the intensity of the flow rate signal in the range 30-300 Hz. In addition, the snore determination algorithm 4326 can include a step of filtering the respiratory flow rate signal Qr to reduce background noise (e.g. sound from air flow in the system from the blower).

[0304] 5.4.3.2.7 Determination of airway patency

[0305] In one form of the present technology, the central controller 4230 executes one or more airway patency determination algorithms 4327 for determining a degree of airway patency.

[0306] In one form, the airway patency determination algorithm 4327 receives as 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 indicative of airway patency. The absence of a peak is considered to be an indication of a closed airway.

[0307] In one form, the frequency range in which the peak is sought is the frequency of a small forced oscillation in the treatment pressure Pt. In one implementation, the frequency of the forced oscillation is 2 Hz and the amplitude is about 1 cmH20.

[0308] In one form, the airway openness determination algorithm 4327 receives as input the respiratory flow rate signal Qr and determines whether a cardiogenic signal is present. The absence of a cardiogenic signal is taken as an indication of a closed airway.

[0309] 5.4.3.2.8 Determination of target ventilation

[0310] In one form of the present technology, the central controller 4230 receives as input a measure of the current ventilation Vent and executes one or more target ventilation determination algorithms 4328 for determining a target value Vtgt for the ventilation measure.

[0311] 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 input via the input device 4220.

[0312] In other forms of the present technology, for example adaptive servo ventilation (ASV), the target ventilation determination algorithm 4328 calculates the target value Vtgt from a value Vtyp indicative of a typical recent ventilation of the patient.

[0313] In some forms of adaptive servo ventilation, the target ventilation Vtgt is calculated as a high proportion of, but less than, the typical recent ventilation Vtyp. Such a form of high proportion can be in the range (80%, 100%) or (85%, 95%) or (87%, 92%).

[0314] In other forms of adaptive servo ventilation, the target ventilation Vtgt is calculated as an integer multiple of the typical recent ventilation Vtyp, but slightly greater than the typical recent ventilation Vtyp.

[0315] The typical recent ventilation Vtyp is a value around which a distribution of measures of the current ventilation Vent at multiple times over some predetermined timescale is clustered, i.e. a measure of a central tendency of measures of the current ventilation over a recent history. In one implementation of the target ventilation determination algorithm 4328, the recent history is of the order of a few minutes, but in any case should be longer than the timescale of the tidal inspiratory-expiratory cycle. The target ventilation determination algorithm 4328 can use any of various well-known measures of central tendency to determine the typical recent ventilation Vtyp from measures of the current ventilation Vent. One such measure is the output of a low-pass filter on the measures of the current ventilation Vent with a time constant equal to one hundred seconds.

[0316] 5.4.3.2.9 Determination of therapy parameters

[0317] In some forms of the technology, the central controller 4230 executes one or more treatment parameter determination algorithms 4329 for determining one or more treatment parameters using values returned by one or more other algorithms in the treatment engine module 4320.

[0318] In one form of the technology, the treatment parameter is the instantaneous treatment pressure Pt. In one implementation of this form, the treatment parameter determination algorithm 4329 determines the treatment pressure Pt using the equation

[0319] Pt = A Π(Φ, t) + P0 (1)

[0320] where:

[0321] • A is an amplitude,

[0322] • Π(Φ, t) is a waveform template value (in the range 0 to 1) at a current value Φ of the phase and time t, and

[0323] • P0 is a base pressure.

[0324] If the waveform determination algorithm 4322 provides the waveform template Π(Φ, t) as a lookup table of values Π indexed by phase Φ, then the treatment parameter determination algorithm 4329 applies equation (1) by locating the lookup table entry that is closest to the current value Φ of the phase returned by the phase determination algorithm 4321, or by interpolating between two entries across the current value Φ of the phase.

[0325] The values of the amplitude A and the base pressure P0 can be set by the treatment parameter determination algorithm 4329 in dependence on the selected respiratory pressure treatment mode in the following manner.

[0326] 5.4.3.3 Treatment Control Module

[0327] The treatment control module 4330 according to an aspect of the technology receives as input the treatment parameters from the treatment parameter determination algorithm 4329 of the treatment engine module 4320, and controls the pressure generator 4140 to deliver a flow of air in accordance with the treatment parameters.

[0328] In one form of the technology, the treatment parameter is the treatment pressure Pt, and the treatment control module 4330 controls the pressure generator 4140 to deliver a flow of air at the interface pressure Pmat the patient interface 3000 or 3800 that is equal to the treatment pressure Pt.

[0329] 5.4.3.4 Detection of Fault Conditions

[0330] In one form of the technology, the central controller 4230 executes one or more methods 4340 for detecting fault conditions. The fault conditions detected by the one or more methods 4340 can include at least one of:

[0331] • Power failure (no power or insufficient power)

[0332] • Transducer failure detection

[0333] • Failure to detect presence of component

[0334] • Operating parameters outside recommended range (e.g. pressure, flow rate, temperature, Pa02)

[0335] • Test alarm fails to generate a detectable alarm signal.

[0336] Upon detection of a fault condition, the corresponding algorithm 4340 signals the presence of a fault by one or more of the following:

[0337] • Initiating an audible, visual and / or dynamic (e.g. vibration) alarm

[0338] • Sending a message to an external device

[0339] • Event logging

[0340] 5.5 Air circuit

[0341] An air circuit 4170 according to an aspect of the present technology is a conduit or tube which, in use, is constructed and arranged to allow a flow of air to travel between two components, such as the RPT device 4000 and the patient interface 3000 or 3800.

[0342] In particular, the air circuit 4170 can be in fluid connection with the outlet of the pneumatic block 4020 and the patient interface. The air circuit can be referred to as an air delivery tube. In some cases, there can be separate limbs for inhalation and exhalation circuits. In other cases, a single limb is used.

[0343] In some forms, the air circuit 4170 can include one or more heating elements configured to heat air in the air circuit, for example to maintain or raise the temperature of the air. The heating elements can be in the form of a heating wire circuit, and can include one or more transducers, such as temperature sensors. In one form, the heating wire circuit can be helically wound around the axis of the air circuit 4170. The heating elements can be in communication with a controller, such as the central controller 4230. One example of an air circuit 4170 including a heating wire circuit is described in US Patent 8,733,349, which is incorporated herein in its entirety by reference.

[0344] 5.5.1 Supplementary gas delivery

[0345] In one form of the technology, a supplemental gas (e.g. oxygen) 4180 is delivered to one or more points in the pneumatic path, for example upstream of the pneumatic block 4020, to the air circuit 4170 and / or to the patient interface 3000.

[0346] 5.6 Humidifier

[0347] 5.6.1 Humidifier Overview

[0348] In one form of the technology, a humidifier 5000 (e.g. as shown in Figure 5A is provided 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 of the air flow and increase the temperature of the air flow (relative to ambient air) prior to delivery to the airways of a patient.

[0349] The humidifier 5000 can include a humidifier reservoir 5110, a humidifier inlet 5002 for receiving an air flow, and a humidifier outlet 5004 for delivering a humidified air flow. In some forms, as shown in Figure 5A and Figure 5B the inlet and outlet of the humidifier reservoir 5110 can be the humidifier inlet 5002 and the humidifier outlet 5004 respectively. The humidifier 5000 can also include a humidifier base 5006 which can be adapted to receive the humidifier reservoir 5110 and which includes a heating element 5240.

[0350] 5.6.2 Humidifier Components

[0351] 5.6.2.1 Water Reservoir

[0352] According to one arrangement, the humidifier 5000 can include a water reservoir 5110 configured to hold or retain a volume of liquid (e.g. water) to be vaporised for humidifying an air flow. The water reservoir 5110 can be configured to hold a predetermined maximum water volume so as to provide sufficient humidification for a duration of at least a respiratory session, such as a night of sleep. Typically, the reservoir 5110 is configured to hold a few hundred millilitres of water, for example, 300 millilitres (ml), 325 ml, 350 ml or 400 ml. In other forms, the humidifier 5000 can be configured to receive a supply of water from an external water source such as a building’s water supply system.

[0353] According to one aspect, the water reservoir 5110 is configured to add humidity to an air flow from the RPT device 4000 as the air flow travels therethrough. In one form, the water reservoir 5110 can be configured to facilitate the air flow to travel in a tortuous path through the reservoir 5110 while in contact with a volume of water therein.

[0354] According to one form, the storage 5110 can, for example, be along such a path. Figure 5A and Figure 5B The lateral direction shown is removed from the humidifier 5000.

[0355] The reservoir 5110 may also be configured to prevent liquid from flowing out of it, such as through any hole and / or between its sub-components, when the reservoir 5110 is displaced and / or rotated from its normal operating direction. Since the airflow to be humidified by the humidifier 5000 is typically pressurized, the reservoir 5110 may also be configured to prevent loss of pneumatic pressure due to leakage and / or flow resistance.

[0356] 5.6.2.2 Conductive Component

[0357] According to one arrangement, the reservoir 5110 includes a conductive portion 5120 configured to allow efficient heat transfer from the heating element 5240 to the liquid volume within the reservoir 5110. In one form, the conductive portion 5120 may be arranged as a plate, but other shapes are equally applicable. All or part of the conductive portion 5120 may be made of a thermally conductive material, such as aluminum (e.g., with a thickness of approximately 2 mm, such as 1 mm, 1.5 mm, 2.5 mm, or 3 mm), another thermally conductive metal, or some plastics. In some cases, suitable thermal conductivity may be achieved using materials with appropriate geometries and lower thermal conductivity.

[0358] 5.6.2.3 Humidifier storage base

[0359] In one form, the humidifier 5000 may include a humidifier reservoir base 5130 (e.g., Figure 5B As shown, it is configured to receive a humidifier reservoir 5110. In some arrangements, the humidifier reservoir base 5130 may include locking features, such as a locking lever 5135 configured to hold the reservoir 5110 in the humidifier reservoir base 5130.

[0360] 5.6.2.4 Water level indicator

[0361] The humidifier storage unit 5110 may include, for example: Figure 5A-5B The water level indicator 5150 is shown. In some forms, the water level indicator 5150 may provide a user (such as a patient 1000 or a caregiver) with one or more indications regarding the amount of water in the humidifier reservoir 5110. The one or more indications provided by the water level indicator 5150 may include an indication of the maximum predetermined volume of water, any portion thereof, such as 25%, 50%, 75%, or a volume such as 200 ml, 300 ml, or 400 ml.

[0362] 5.6.2.5 Humidifier Converter

[0363] The humidifier 5000 can include one or more humidifier transducers (sensors) 5210 in addition to or instead of the transducers 4270 described above. As shown, the humidifier transducers 5210 can include one or more of an air pressure sensor 5212, an air flow transducer 5214, a temperature sensor 5216, or a humidity sensor 5218. The humidifier transducers 5210 can generate one or more output signals that can be communicated to a controller, such as the central controller 4230 and / or the humidifier controller 5250. In some forms, the humidifier transducers can be located externally of the humidifier 5000 (such as in the air circuit 4170) when communicating output signals to the controller. Figure 5C

[0364] 5.6.2.5.1 Pressure transducer

[0365] In addition to, or instead of, the pressure sensor 4272 provided in the RPT device 4000, one or more pressure transducers 5212 can be provided to the humidifier 5000.

[0366] 5.6.2.5.2 Air flow transducer

[0367] In addition to, or instead of, the flow sensor 4274 provided in the RPT device 4000, one or more flow transducers 5214 can be provided to the humidifier 5000.

[0368] 5.6.2.5.3 Temperature transducer

[0369] The humidifier 5000 can include one or more temperature transducers 5216. The one or more temperature transducers 5216 can be configured to measure one or more temperatures of, for example, the heating element 5240 and / or the air flow downstream of the humidifier outlet 5004. In some forms, the humidifier 5000 can also include a temperature sensor 5216 to detect the temperature of ambient air.

[0370] 5.6.2.5.4 Humidity transducer

[0371] In one form, the humidifier 5000 can include one or more humidity sensors 5218 to detect the humidity of a gas (e.g. ambient air). The humidity sensor 5218 can be provided in some forms towards the humidifier outlet 5004 to measure the humidity of the gas delivered from the humidifier 5000. The humidity sensor can be an absolute humidity sensor or a relative humidity sensor.

[0372] 5.6.2.6 Heating element

[0373] ​In some cases, a humidifier 5000 can be provided with a heating element 5240 to provide a heat input to one or more volumes of water and / or air flow in the humidifier reservoir 5110. The heating element 5240 can include a heat-generating component, such as a resistive heating track. One suitable example of a heating element 5240 is a laminar heating element, such as described in PCT Patent Application Publication No. WO 2012 / 171072, which is incorporated herein by reference in its entirety.

[0374] In some forms, the heating element 5240 can be provided in the humidifier base 5006, where heat can be provided to the humidifier reservoir 5110 primarily by conduction, as Figure 5B illustrated.

[0375] 5.6.2.7 Humidifier Controller

[0376] According to arrangements of the present technology, the humidifier 5000 can include a humidifier controller 5250 as Figure 5C illustrated. In one form, the humidifier controller 5250 can be part of the central controller 4230. In another form, the humidifier controller 5250 can be a separate controller, which can be in communication with the central controller 4230.

[0377] In one form, the humidifier controller 5250 can receive as input measurements of characteristics of the flow of, for example, air, water in the reservoir 5110 and / or the humidifier 5000, such as temperature, humidity, pressure, and / or flow rate. The humidifier controller 5250 can also be configured to execute or implement a humidifier algorithm and / or deliver one or more output signals.

[0378] As Figure 5C illustrated, the humidifier controller 5250 can include one or more controllers, such as a central humidifier controller 5251, a heated air circuit controller 5254 configured to control the temperature of the heated air circuit 4171, and / or a heating element controller 5252 configured to control the temperature of the heating element 5240.

[0379] 5.7 Tube Type Identification

[0380] In one form of the technology, there is provided a system and / or method for identifying the type of a peripheral component connected to an RPT device 4000, for example, the type of air delivery tube 4170 and / or patient interface. In some examples, the air delivery tube type can be determined based on one or more unique electrical characteristics of the air delivery tube 4170 and / or one or more unique connectors of the air delivery tube 4170. In one example, a contact assembly of the air delivery tube 4170 that couples the air delivery tube 4170 to the RPT device 4000 can be used as an identifier of various parameters of the air delivery tube 4170 and / or patient interface. For example, the contact assembly can be configured to provide identification of the type of air delivery tube 4170 (e.g. non-heated tube, heated tube, tube with a heat and moisture exchanger (HME), unknown tube), the size of the air delivery tube (e.g. 15mm, 19mm), the presence and type of HME, the type of patient interface connected to the tube, and the like. The data from the identification can be communicated and used by the controller to optimise the operation of the RPT device 4000 and / or humidifier 5000. For example, the controller can be configured to identify unique identification features so that the controller can identify the specific features of the air delivery tube 4170 coupled to the RPT device 4000, and thus the controller can automatically configure the RPT device 4000 and / or humidifier 5000 for optimised operation.

[0381] Figure 5D-5H Schematic diagrams of air delivery tubes 4170 connected to an RPT device 4000 are shown in accordance with various forms of the technology. Each schematic diagram shows that the air delivery tube 4170 can provide different features that can be used to identify the type of tube connected to the RPT device 4000.

[0382] The RPT device 4000 can include a contact assembly 6200 for mechanically and electrically coupling to a tube connector 6300 to provide power, signals and / or air to the air delivery tube 4170. The contact assembly 6200 can be provided as a separate component that is coupled to or integrated into the housing of the RPT device 4000 or humidifier 5000. The connection in the tube can be a solid pin, but is not limited thereto. In some examples, the connection can be provided by, for example, a lead frame terminal. In one example, when the connection tube 4170 is connected, the solid pin in one device is connected to a corresponding spring single high pin in the other device.

[0383] In one form of the disclosure, the contact assembly 6200 includes four connections coupled to processing circuitry 6400. The processing circuitry 6400 can be provided as part of the central controller 4230, the central humidifier controller 5251, the air circuit controller 5254, or a separate circuit coupled to the central controller 4230, the central humidifier controller 5251, and / or the air circuit controller 5254. The processing circuitry 6400 can include one or more analog and / or digital hardware elements for performing the operations discussed in this application.

[0384] In one form of the disclosure, at least two connections (heating line 1 and heating line 2) are coupled to a heating control circuit, and two connections (sensor line 1 and sensor line 2) are coupled to a heating tube detection circuit. One heating line can be coupled to the heating control circuit ground. In some examples, one or both of the sensor line connections can be coupled to a sensor 6500 having a temperature-dependent electrical characteristic (e.g., resistance). The sensor 6500 can include a thermistor formed of a negative temperature coefficient (NTC) material. The parameters (e.g., resistance) of the thermistor can vary with changes in tube temperature.

[0385] The heater control circuit can supply power to the heating element in the tube 4170 via a switch (e.g., a transistor). The heating element can include a heating wire distributed along at least a portion of the length of the tube 4170 to the mask end of the tube 4170. The heater control circuit can control the duration, voltage, and / or frequency and / or period of a pulse width modulation (PWM) signal provided to the heating element 5240 in the tube 4170.

[0386] The heating tube detection circuit can be configured to receive a signal from a sensor 6500 disposed in the tube 4170 indicative of operation of the heating element in the tube 4170. The sensor 6500 can be disposed at the mask proximal end of the tube 4170. For example, the heating tube detection circuit can measure the voltage and / or current of the sensor 6500 to determine an operating characteristic (e.g., temperature) of the heating element. The heater control circuit can control the heating element based on the signal received by the heating tube detection circuit and the settings of the heating tube 4170. Other sensors, i.e., humidity sensors, disposed anywhere in the tube can also be connected in a similar manner.

[0387] The heated tube detection circuit can automatically identify the type of tube 4170 connected to the RPT device 4000 based on a unique characteristic(s) provided by active and / or passive components in the tube 4170 or by the absence of any connecting components via one or more of the four electrical connectors between the tube 4170 and the RPT device 4000. Based on the indicated type of connected tube 4170, the controller can change operating parameters of the system. For example, different heating control settings can be provided for different tubes (e.g., non-heated tube, heated tube, tube with a heat and moisture exchanger (HME), unknown tube). In some examples, the settings can be modified based on the identified size of the air delivery tube (e.g., 15 mm, 19 mm), the presence and type of HME, the type of patient interface connected to the tube, and the like.

[0388] 5.7.1 Four-pin, four-wire identification

[0389] In Figure 5D the heating element is coupled to two pins in the tube 4170 and the sensor 6500 is coupled to two other pins in the tube 4170. The characteristics of the sensor 6500 and / or the heating element can be used to identify the type of tube connected to the RPT device 4000. For example, the thermistor can be selected based on the type of air delivery tube 4170. A 10k thermistor can be provided in a first type of tube (e.g., a 15 mm hot air tube), a 100k thermistor can be provided in a second type of tube (e.g., a 19 mm hot air tube), and an open circuit can be provided in a third type of tube (e.g., a passive air tube without a heating element). The different resistance values provided by the sensor 6500 can allow the processing circuit 6400 to determine the type of connected tube and which control parameters to use for operation of the RPT device 4000. Tube detection using as described in U.S. Provisional Application 62 / 835,094, filed April 17, 2019, the contents of which are incorporated by reference herein in their entirety, can be applied to the present technology disclosure.

[0390] 5.7.2 Four-pin, three-wire identification

[0391] Because using certain thermistors can provide more accurate measurements of the temperature in the air delivery tube 4170, certain example embodiments provide for identifying the air delivery tube type without using sensors with different characteristics (e.g., resistance). In one example, a 10K thermistor can be used in different air delivery tubes 4170 to provide more accurate in-tube temperature measurements compared to a 100K thermistor.

[0392] Figure 5E and Figure 5F A schematic of an air delivery tube 4170 connected to the RPT device 4000 is shown in which one of the sensor lines is not coupled to the sensor 6500. Figure 5Eand Figure 5F The sensor 6500 shown can have the same characteristics as... Figure 5D The parameters of the sensor 6500 shown are similar to those of the sensor described. In one example, Figure 5D , Figure 5E and Figure 5F The sensor 6500 in the text can be a 10k thermistor.

[0393] exist Figure 5E and Figure 5F In this configuration, sensor 6500 is connected to only one of the sensor wires and the heating wires. Sensor 6500 can be connected to one or more heating wires via a heating element, or it can be directly connected to a heating wire via a connection in pipe connector 6300, bypassing the heating element in one or more heating wires. In one example, sensor 6500 can be connected to one of the sensor wires, and the pins in pipe connector 6300 are connected to ground of the heating tube control circuit.

[0394] Different air delivery pipe types can be specified by connecting sensor 6500 to different sensor lines from multiple sensor lines (two sensor lines are shown, but more can be included). For example, a first pipe type (e.g., a 15 mm hot air pipe) can be specified by connecting sensor 6500 to sensor line 2 and the heating line, and a second pipe type (e.g., a 19 mm hot air pipe) can be specified by connecting sensor 6500 to sensor line 1 and the heating line.

[0395] exist Figure 5E and Figure 5F In the examples shown, the contact assembly 6200 of the RPT device 4000 may include a 4-pin connection, while the tube connector 6300 may include a 3-pin connection. Different ways in which the lower number of pins in the air delivery tube 4170 connects to the higher number of pins in the RPT device 4000 can be used to distinguish the different air delivery tubes 4170. In these examples, the air delivery tube 4170 may include three wires (i.e., two for the heating element and one for the sensor 6500) extending within the tube to the tube end coupled to the patient interface 3000. In some examples, additional pins that are not electrically connected to any component of the air delivery tube may be provided in the tube connector 6300. In other examples, the tube connector 6300 may not include additional electrical pins (e.g., a fourth pin).

[0396] The heating tube detection circuit can determine the type of air delivery tube 4170 coupled to the RPT device 4000 by measuring the presence and / or absence of a signal on the pins of the contact assembly 6200. If there is no signal on sensor line 1, the heating tube detection circuit can identify a first type of air delivery tube. If there is no signal on sensor line 2, the heating tube detection circuit can identify a second type of air delivery tube.

[0397] In another example, there is a signal on sensor line 2, and then the heating tube detection circuit can identify a first type of air delivery tube. If there is a signal on sensor line 1, the heating tube detection circuit can identify a second type of air delivery tube.

[0398] In some examples, the absence of a signal on both sensor lines can indicate that the air delivery tube is not connected to the RPT device 4000, or that a third type of air delivery tube (e.g. a non-heated tube) is coupled to the RPT device 4000.

[0399] Figure 5G and Figure 5H A schematic of an air delivery tube 4170 connected to an RPT device 4000 is shown, where signals measured by the detection lines are used to identify the type of air delivery tube 4170 coupled to the RPT device 4000. In Figure 5G and Figure 5H In the RPT device 4000, the heating control circuit can power the heating element in the air delivery tube 4170 through the heating line and ground. The control circuit can determine the temperature in the air delivery tube 4170 by measuring the signal from the sensor 6500 through the sensor line and ground.

[0400] The heating tube detection circuit can determine the air delivery tube type based on the signals received via the detection lines in the contact assembly 6200. As Figure 5G shown, a first tube type (e.g. a 15mm hot air tube) can be specified by the absence of an electrical connection (or pin) to the detection lines in the contact assembly 6200 in the tube connector 6300. As Figure 6H shown, a second tube type (e.g. a 19mm hot air tube) can be specified by a pin in the tube connector 6300 that is electrically connected (e.g. in a ferrule bladder) by a detectable electrical connection 6350. The electrical connection 6350 can comprise, for example, a flat short, a resistive connection, a shunt, an asymmetric (e.g. diode type), or an active signal. As Figure 5HAs shown, an electrical connection 6350 can be provided between the detection line and the ground terminal of the contact assembly 6200 and the tube connector 6300.

[0401] The heated tube detection circuit can determine the type of air delivery tube 4170 coupled to the RPT device 4000 by measuring the presence and / or absence of circuit components on the detection line of the contact assembly 6200. For example, a voltage can be applied to the detection line to determine whether there is a current via components coupled between the detection line and ground. If there is no signal on the detection line (as shown in Figure 5G The heated tube detection circuit can identify a first type of air delivery tube. If there is a signal on the detection line (as shown in Figure 5H The heated tube detection circuit can identify a second type of air delivery tube.

[0402] In some examples, different types of electrical connections 6350 (e.g. different values of resistive elements) can be used to further distinguish between different types of air delivery tube, and the heated tube detection circuit can determine the type of tube based on the signal received via the detection line.

[0403] In another example, when there is a signal on sensor line 2, then the heated tube detection circuit can identify a first type of air delivery tube. When there is a signal on sensor line 1, then the heated tube detection circuit can identify a second type of air delivery tube.

[0404] The heated tube detection circuit can determine the type of air delivery tube 4170 coupled to the RPT device 4000 by determining whether a circuit including the detection line and one of the other connections (e.g. one of the heating lines) is open or closed. A first type of air delivery tube can be identified when the circuit is open, and a second type of air delivery tube can be identified when the circuit is closed (e.g. due to a resistor or shunt coupling the detection line to one of the other connections in the air delivery tube 4170).

[0405] The air delivery tube identification can be performed based on signals received from the sensor lines and / or detection lines in the hardware and / or software. In some examples, the hardware and / or software can be configured to perform the tube identification when the RPT device 4000 is started, when the air delivery tube is connected to the RPT device 4000, periodically during operation of the RPT device 4000, and / or at the start of operation of the RPT device 4000.

[0406] Figure 5I An example heated tube detection circuit according to one form of the present technology is shown. Figure 5I The heated tube detection circuit shown in Figure 5E and 5F can be used to identify the air delivery tube type using the identification circuit provided in

[0407] The comparator 5290 can be coupled to the sensor lines and provide an output signal to the controller 5250 which is configured to control the heating element 5240, the heated air circuit 4171 and / or other components of the RPT device 4000 based on the determined tube type and data received from the sensor 5210. The sensor line 1 and the sensor line 2 can be coupled to a comparator which is configured to compare the signals received via the sensor lines. The comparator can output a first value (e.g. zero) if the signal on the sensor line 1 is lower than the signal on the sensor line 2 (as shown in the configuration in Figure 5E Figure 5F The comparator can output a second value (e.g. one) if the signal on the sensor line 2 is lower than the signal on line 1 (as shown in the configuration inIn this example, the digital output of 1 or 0 can distinguish between the two tube types and indicate the type of air delivery tube 4170 coupled to the RPT device 4000. In some examples, the comparator 5290 can be further configured to determine when the signal on the sensor lines is equal to an indication of a third type of air delivery tube 4170 or the absence of an air delivery tube 4170. The third type of air delivery tube can correspond to an air delivery tube without a heating element and / or sensor.

[0408] Figure 5J An example heating tube detection circuit according to another form of the technology is shown. Figure 5J The heating tube detection circuit shown in Figure 5G and Figure 5H may be used to identify the air delivery tube type using the identification circuit provided in

[0409] The comparator 5292 can be coupled to the detection line and provide an output signal to the controller 5250 which is configured to control the heating element 5240, the heated air circuit 4171 and / or other components of the RPT device 4000 based on the determined tube type and data received from the sensor 5210. The detection line can be coupled to a comparator which is configured to compare the signal received via the detection line to a reference value (e.g. ground or a reference voltage). The comparator 5292 can output a first value (e.g. 1) if the signal on the detection line is higher than the reference value (as shown in the configuration in Figure 5H Figure 5G The comparator 5292 can output a second value (e.g. 0) if the signal on the detection line is equal to or lower than the reference value (as shown in the configuration inIn this example, the digital output of 1 or 0 can indicate the type of air delivery tube 4170 coupled to the RPT device 4000.

[0410] While the above examples of the present technology have been described with reference to three- or four-wire systems and connectors having three or pins in the connector, these examples are not limited to this. Examples of the present technology can be applied to systems having other numbers of wires (e.g. two wires, three wires, or five or more wires) and / or other numbers of pins. For example, additional sensor wires can be included in the RPT device 4000 to distinguish between a number of air delivery tube types.

[0411] 5.8 Breathing Waveform

[0412] Figure 6A A typical breathing waveform of a person sleeping is shown. The horizontal axis is time, and the vertical axis is respiratory flow rate. While the parameter values can vary, a typical breath can have the following approximate values: tidal volume Vt 0.5 L, inspiration time Ti 1.6 s, peak inspiratory flow rate Qpeak 0.4 L / s, expiration time Te 2.4 s, peak expiratory flow rate Qpeak -0.5 L / s. The total duration of the breath Ttot is approximately 4 s. The person is typically breathing at a rate of approximately 15 breaths per minute (BPM), with a ventilation of approximately 7.5 L / min. The typical duty cycle, the ratio of Ti to Ttot, is approximately 40%.

[0413] Figure 6B Selected polysomnogram channels (pulse oximetry, flow, chest movement, and abdominal movement) of a patient during a non-REM sleep breath, which is typically over a period of about 90 seconds, with about 34 breaths, treated with auto-PAP therapy, and an interface pressure of about 11 cmH20, are shown. The top channel shows pulse oximetry (oxygen saturation or Sp02), with a scale in the vertical direction having a range of saturation from 90% to 99%. The patient maintains a saturation of about 95% throughout the period shown. The second channel shows quantitative respiratory airflow, with a scale in the vertical direction from -1 to +1 LPS, and inspiration is positive. Chest and abdominal movements are shown in the third and fourth channels.

[0414] Figure 6CA polysomnogram of a patient before treatment is shown. From top to bottom there are 11 signal channels with a horizontal span of 6 minutes. The first two channels are both EEG (electroencephalogram) from different scalp locations. The periodic spikes in the second EEG indicate cortical arousal and associated activity. The third channel down is submental EMG (electromyogram). The increase around the arousal times indicates the genioglossus muscle recruitment. The fourth and fifth channels are EOG (electrooculogram). The sixth channel is an electrocardiogram. The seventh channel shows pulse oximetry (Sp02) with repeated desaturations from about 90% to below 70%. The eighth channel is respiratory airflow using a nasal cannula connected to a differential pressure transducer. The repeated apneas of 25 to 35 seconds alternate with recovery breath bursts of 10 to 15 seconds, consistent with the EEG arousal and increased EMG activity. The ninth channel indicates chest movement and the tenth channel indicates abdominal movement. The abdomen shows increasing movement over the length of the apnea leading to arousal. Both become disorganized during arousal due to whole body movement during recovery breaths. The apneas are therefore obstructive and the condition is severe. The lowest channel is posture and it does not show changes in this example.

[0415] Figure 6D Patient flow data is shown for a patient experiencing a series of complete obstructive apneas. The duration of the recording is approximately 160 seconds. The flow range is about +1 L / s to about -1.5 L / s. Each apnea lasts approximately 10-15 seconds.

[0416] Figure 6E A scaled inspiration portion of a breath is shown for a patient experiencing low frequency inspiratory snoring.

[0417] Figure 6F A scaled inspiration portion of a breath is shown for a patient experiencing an example of flattening inspiratory flow limitation.

[0418] Figure 6G A scaled inspiration portion of a breath is shown for a patient experiencing an example of "table top" flattening inspiratory flow limitation.

[0419] Figure 6H A scaled inspiration portion of a breath is shown for a patient experiencing an example of "panda ear" inspiratory flow limitation.

[0420] Figure 6I A scaled inspiration portion of a breath is shown for a patient experiencing an example of "chair" inspiratory flow limitation.

[0421] Figure 6J A scaled inspiration portion of a breath is shown for a patient experiencing an example of "reverse chair" inspiratory flow limitation.

[0422] Figure 6KA scaled inhalation portion of respiration showing an example of a patient experiencing an "M-shaped" inspiratory flow limitation.

[0423] Figure 6L A scaled inhalation portion of respiration showing an example of a patient experiencing a severe "M-shaped" inspiratory flow limitation.

[0424] Figure 6M Patient data from a patient with Cheyne-Stokes respiration is shown. There are three channels: pulse oximetry (Sp02); a signal representing flow; and chest movement. The data spans six minutes. The signal representing flow is measured using a pressure sensor connected to a nasal cannula. The patient exhibits an apnoea of about 22 seconds and a hypopnoea of about 38 seconds. The higher frequency, low amplitude oscillations during the apnoea are cardiogenic.

[0425] Figure 6N Patient data from another example of a patient with Cheyne-Stokes respiration is shown using the same three channels as in Figure 6M the previous example. The data spans 10 minutes. The patient exhibits a hypopnoea of about 30 seconds and a hyperpnoea of about 30 seconds.

[0426] 5.9 Respiratory therapy modes

[0427] A variety of respiratory therapy modes can be implemented by the disclosed respiratory therapy system.

[0428] 5.9.1 CPAP therapy

[0429] In some implementations of respiratory pressure therapy, the central controller 4230 sets the therapy pressure Pt according to a therapy pressure equation (1) that is part of a therapy parameter determination algorithm 4329. In one such implementation, the amplitude A is likewise zero, so the therapy pressure Pt (which represents a target value to be achieved by the interface pressure Pm at the current time instant) likewise equals the base pressure P0 throughout the respiratory cycle. Such implementations are generally grouped under the heading of CPAP therapy. In such implementations, the therapy engine module 4320 does not need to determine the phase Φ or the waveform template Π(Φ).

[0430] In CPAP therapy, the base pressure P0 can be a constant value that is hard-coded or manually entered into the RPT device 4000. Alternatively, the central controller 4230 can repeatedly calculate the base pressure P0 as a function of an index or measure of sleep disordered breathing returned by a corresponding algorithm in the therapy engine module 4320, such as one or more of flow limitation, apnoea, hypopnoea, open airway, and snoring. This option is sometimes referred to as APAP therapy.

[0431] Figure 4Eis a flowchart illustrating a method 4500 performed by the central controller 4230 for continuously calculating a base pressure Po as part of the APAP therapy implementation of the therapy parameter determination algorithm 4329 when pressure support A is equal to zero.

[0432] The method 4500 begins at step 4520, where the central controller 4230 compares a measure of the presence of apnea / hypopnea to a first threshold and determines whether the measure of the presence of apnea / hypopnea has exceeded the first threshold for a predetermined period of time, indicating that an apnea / hypopnea is occurring. If so, the method 4500 proceeds to step 4540; otherwise, the method 4500 proceeds to step 4530. At step 4540, the central controller 4230 compares a measure of airway patency to a second threshold. If the measure of airway patency exceeds the second threshold, indicating that the airway is open, the detected apnea / hypopnea is deemed central, and the method 4500 proceeds to step 4560; otherwise, the apnea / hypopnea is deemed obstructive, and the method 4500 proceeds to step 4550.

[0433] At step 4530, the central controller 4230 compares a measure of flow limitation to a third threshold. If the measure of flow limitation exceeds the third threshold, indicating that inspiratory flow is limited, the method 4500 proceeds to step 4550; otherwise, the method 4500 proceeds to step 4560.

[0434] At step 4550, the central controller 4230 increases the base pressure Po by a predetermined pressure increment AP, so long as the resulting therapy pressure Pt does not exceed a maximum therapy pressure Pmax. In one implementation, the predetermined pressure increment AP and the maximum therapy pressure Pmax are 1 cmH20 and 25 cmH20, respectively. In other implementations, the pressure increment AP can be as low as 0.1 cmH20 and as high as 3 cmH20, or as low as 0.5 cmH20 and as high as 2 cmH20. In other implementations, the maximum therapy pressure Pmax can be as low as 15 cmH20 and as high as 35 cmH20, or as low as 20 cmH20 and as high as 30 cmH20. The method 4500 then returns to step 4520.

[0435] At step 4560, the central controller 4230 decreases the base pressure P0 by a decrement as long as the decreased base pressure P0 does not fall below a minimum therapy pressure Pmin. The method 4500 then returns to step 4520. In one implementation, the decrement is proportional to the value of P0-Pmin, such that the decrease of P0 to the minimum therapy pressure Pmin is exponential in the absence of any detected events. In one implementation, the proportionality constant is set such that the time constant τ of the exponential decrease of P0 is 60 minutes, and the minimum therapy pressure Pmin is 4 cmH20. In other embodiments, the time constant τ can be as low as 1 minute and as high as 300 minutes, or as low as 5 minutes and as high as 180 minutes. In other implementations, the minimum therapy pressure Pmin can be as low as 0 cmH20 and as high as 8 cmH20, or as low as 2 cmH20 and as high as 6 cmH20. Alternatively, the decrease of P0 can be predetermined, such that the decrease of P0 to the minimum therapy pressure Pmin is linear in the absence of any detected events.

[0436] 5.9.2 Bi-level Therapy

[0437] In other implementations of this form of the technology, the value of the amplitude A in equation (1) can be positive. Such is referred to as bi-level therapy, because in determining the therapy pressure Pt using equation (1) with a positive amplitude A, the therapy parameter determination algorithm 4329 oscillates the therapy pressure Pt between two values or levels in synchrony with the spontaneous respiratory effort of the patient 1000. That is, based on the typical waveform template Π(Φ, t) described above, the therapy parameter determination algorithm 4329 increases the therapy pressure Pt to P0+A at the start or during or inspiration (referred to as IPAP), and decreases the therapy pressure Pt to the base pressure P0 at the start or during expiration (referred to as EPAP).

[0438] In some forms of bi-level therapy, IPAP is a therapy pressure of the same purpose as the therapy pressure in CPAP therapy mode, and EPAP is IPAP minus an amplitude A, which has a "small" value (a few cmH20), sometimes referred to as expiratory pressure relief (EPR). This form is sometimes referred to as CPAP therapy with EPR, which is generally considered more comfortable than direct CPAP therapy. In CPAP therapy with EPR, both IPAP and EPAP can be constant values that are hard-coded or manually entered to the RPT device 4000. Alternatively, the therapy parameter determination algorithm 4329 can repeatedly calculate IPAP and / or EPAP during CPAP with EPR. In this alternative, the therapy parameter determination algorithm 4329 repeatedly calculates EPAP and / or IPAP as a function of an indicator or measure of sleep disordered breathing returned by a respective algorithm in the therapy engine module 4320, in a similar manner to the calculation of the base pressure P0 in APAP therapy described above.

[0439] In other forms of bi-level therapy, the amplitude A is large enough that the RPT device 4000 does some or all of the work of breathing of the patient 1000. In this form, referred to as pressure support ventilation therapy, the amplitude A is referred to as pressure support or swing. In pressure support ventilation therapy, IPAP is the base pressure P0 plus the pressure support A, and EPAP is the base pressure P0.

[0440] In some forms of pressure support ventilation therapy, referred to as fixed pressure support ventilation therapy, the pressure support A is fixed at a predetermined value, for example 10 cmH20. The predetermined pressure support value is a setting of the RPT device 4000, and can be set, for example, by hard-coding during configuration of the RPT device 4000 or by manual input through the input device 4220.

[0441] In other forms of pressure support ventilation therapy, broadly referred to as servo- ventilation, the therapy parameter determination algorithm 4329 takes as input some current measured or estimated parameter of the respiratory cycle (for example, the current measure of ventilation Vent) and a target value for that respiratory parameter (for example, a target value for ventilation Vtgt), and repeatedly adjusts the parameters of equation (1) to bring the current measure of the respiratory parameter close to the target value. In a form of servo- ventilation known as adaptive servo- ventilation (ASV), which has been used to treat CSR, the respiratory parameter is the volume of ventilation, and the target ventilation value Vtgt is calculated by the target ventilation determination algorithm 4328 from the typical recent ventilation volume Vtyp, as described above.

[0442] In some forms of servo-ventilation, the therapy parameter determination algorithm 4329 applies a control method to repeatedly calculate the pressure support A so as to bring the current measurement of the respiratory parameter close to the target value. One such control method is proportional-integral (PI) control. In one implementation of PI control, applied to ASV modes in which the target ventilation Vtgt is set to be slightly less than the typical recent ventilation Vtyp, the pressure support A is repeatedly calculated as:

[0443] A = G ∫ (Vent - Vtgt) dt (2)

[0444] where G is the gain of the PI control. A larger gain G value can result in positive feedback in the therapy engine module 4320. A smaller gain G value can allow some residual untreated CSR or central sleep apnoea. In some implementations, the gain G is fixed at a predetermined value, for example -0.4 cmH20 / (L / min) / sec. Alternatively, the gain G can vary between therapy sessions, decreasing from one session and increasing from one session to another until a value is reached that substantially eliminates CSR. Conventional means for retrospectively analysing parameters of a therapy session to assess the severity of CSR during the therapy session can be employed in such implementations. In other implementations, the gain G can vary according to the difference between the current measurement of ventilation Vent and the target ventilation Vtgt.

[0445] Other servo-ventilation control methods that can be applied by the therapy parameter determination algorithm 4329 include proportional (P), proportional-derivative (PD) and proportional-integral-derivative (PID).

[0446] The value of pressure support A calculated via equation (2) can be clipped to a range defined as [Amin, Amax]. In this implementation, the pressure support A defaults to the minimum pressure support Amin until the measured value of current ventilation Vent falls below the target ventilation Vtgt, at which point A begins to increase, falling back to Amin only when Vent exceeds Vtgt again.

[0447] The pressure support limits Amin and Amax are settings of the RPT device 4000, for example set by hard-coding during configuration of the RPT device 4000 or by manual input via the input device 4220.

[0448] In the pressure support ventilation therapy mode, the EPAP is the base pressure P0. Like the base pressure P0 in CPAP therapy, the EPAP can be a constant value specified or determined during titration. Such a constant EPAP can be set, for example, by hard-coding during configuration of the RPT device 4000 or by manual input by the input device 4220. This alternative is sometimes referred to as fixed-EPAP pressure support ventilation therapy. During a titration session, a clinician can perform titration of the EPAP for a given patient with the aid of PSG with the aim of preventing obstructive apneas, thereby maintaining an open airway for pressure support ventilation therapy, in a manner similar to titration of the base pressure P0 in constant CPAP therapy.

[0449] Alternatively, the therapy parameter determination algorithm 4329 can repeatedly calculate the base pressure P0 during pressure support ventilation therapy. In such implementations, the therapy parameter determination algorithm 4329 repeatedly calculates the EPAP as a function of an index or measure of sleep disordered breathing returned by a respective algorithm in the therapy engine module 4320, such as one or more of flow limitation, apneas, hypopneas, open airway, and snoring. Because the continuous calculation of EPAP is analogous to manual adjustment of EPAP by a clinician during EPAP titration, this process is also sometimes referred to as automatic titration of EPAP, and the therapy mode is referred to as automatic-titration-EPAP pressure support ventilation therapy or automatic-EPAP pressure support ventilation therapy.

[0450] 5.9.3 High flow therapy

[0451] In other forms of respiratory therapy, the pressure of the flow of gas is not controlled as in respiratory pressure therapy. Rather, the central controller 4230 controls the pressure generator 4140 to deliver a flow of gas whose device flow Qd is controlled to be a therapy or target flow Qtgt that is generally positive throughout the respiratory cycle of the patient. These forms are generally grouped under the heading of flow therapy. In flow therapy, the therapy flow Qtgt can be a constant value that is hard-coded or manually input to the RPT device 4000. If the therapy flow Qtgt is sufficient to exceed the peak inspiratory flow of the patient, the therapy is often referred to as high flow therapy (HFT). Alternatively, the therapy flow can be a profile Qtgt(t) that varies over the respiratory cycle.

[0452] 5.10 Glossary

[0453] To achieve the objects of the present technology disclosure, one or more of the following definitions can be applied in certain forms of the present technology. In other forms of the present technology, alternative definitions can be applied.

[0454] 5.10.1 Overview

[0455] Air: In certain forms of the technology, air can be taken to mean atmospheric air, and in other forms of the technology, air can be taken to mean some other combination of breathable gases, such as atmospheric air enriched with oxygen.

[0456] Environment: In certain forms of the technology, the term environment can have the following meanings (i) the exterior of the therapy system or patient, and (ii) the immediate surroundings of the therapy system or patient.

[0457] For example, the ambient humidity with respect to a humidifier can be the humidity of the air immediately surrounding the humidifier, such as the humidity in the room in which the patient is sleeping. This ambient humidity can be different from the humidity outside the room in which the patient is sleeping.

[0458] In another example, the ambient pressure can be the pressure immediately surrounding or outside the body.

[0459] In certain forms, ambient (e.g. acoustic) noise can be taken to be the background noise level in the room in which the patient is located, other than noise produced by, for example, the RPT device or out of the mask or patient interface. Ambient noise can be produced by sound sources outside the room.

[0460] Automatic positive airway pressure (APAP) therapy: CPAP therapy in which the therapy pressure is automatically adjustable between a minimum and a maximum, for example differing with each breath, depending on whether or not there is an indication of an SBD event.

[0461] Continuous positive airway pressure (CPAP) therapy: Respiratory pressure therapy in which the therapy pressure is approximately constant throughout the respiratory cycle of the 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, increasing in response to detecting an indication of partial airway obstruction, and decreasing in the absence of an indication of partial airway obstruction.

[0462] Flow: Volume (or mass) of air delivered per unit of time. Flow can refer to an instantaneous quantity. In some cases, a reference to flow will be a reference to a scalar quantity, i.e. a quantity that has only a magnitude. In other cases, a reference to flow will be a reference to a vector quantity, i.e. a quantity that has both a magnitude and a direction. Flow can be given the symbol Q. ‘Flow’ is sometimes simply abbreviated to ‘flow’ or ‘air flow’.

[0463] In the example of a patient breathing, the flow can be nominally positive for the inspiration portion of the patient's breathing cycle and thus negative for the expiration portion of the patient's breathing cycle. Device flow Qd is the flow of air leaving the RPT device. Total flow Qt is the flow of air and any supplementary gases to the patient interface via the air circuit. Ventilation flow Qv is the flow of air leaving the vent to allow flushing of exhaled gases. Leak flow Ql is the flow of leaks from the patient interface system or elsewhere. Respiratory flow Qr is the flow of air received into the patient's respiratory system.

[0464] Flow therapy: Respiratory therapy includes the delivery of a flow of air to the entrance of the airways at a controlled flow rate known as the therapy flow rate, which is generally positive throughout the patient's breathing cycle.

[0465] Humidifier: The term humidifier will be taken to mean a humidification apparatus constructed and arranged or configured with a physical structure capable of providing a therapeutically beneficial amount of water (H20) vapour to a flow of air to improve a patient's medical respiratory condition.

[0466] Leak: The word leak will be taken to mean an unwanted flow of air. In one example, a leak can occur due to an imperfect seal between the mask and the patient's face. In another example, a leak can occur in a swivel elbow to ambient.

[0467] Noise, conducted (acoustics): Conducted noise in this document refers to noise brought to the patient through the pneumatic path such as the air circuit and patient interface and the air therein. In one form, conducted noise can be quantified by measuring the sound pressure level at the end of the air circuit.

[0468] Noise, radiated (acoustics): Radiated noise in this document refers to noise brought to the patient through the ambient air. In one form, radiated noise can be quantified by measuring the sound power / pressure level of the object in question according to ISO 3744.

[0469] Noise, vent (acoustics): Vent noise in this document refers to noise produced by the flow of air through any vent such as a vent of a patient interface.

[0470] Patient: A human, whether or not they suffer from a respiratory disorder.

[0471] Pressure: Force per unit area. Pressure can be expressed in a range of units including cmH20, g-f / cm 2 , hectopascals. 1 cmH20 is equivalent to 1 g-f / cm 2 and is approximately 0.98 hectopascals (1 hectopascal = 100 Pa = 100 N / m 2= 1 millibar to 0.001 atmosphere). In this specification, pressure is given in units of cm H2O unless otherwise stated.

[0472] Pressure in the patient interface is given the symbol Pm, while the therapy pressure is given the symbol Pt, which represents the target value achieved by the interface pressure Pm at the current time instant.

[0473] Respiratory Pressure Therapy (RPT): The application of a supply of air at typically positive pressure relative to atmosphere to the entrance of the airways.

[0474] Ventilator: A mechanical device that provides pressure support to a patient to perform some or all of the work of breathing.

[0475] 5.10.1.1 Materials

[0476] Silicone or Silicone Elastomer: A synthetic rubber. In this specification, reference to silicone means Liquid Silicone Rubber (LSR) or Compression Molded Silicone Rubber (CMSR). One form of commercially available LSR is SILASTIC (included in the range of products sold under this trademark) manufactured by Dow Corning. Another manufacturer of LSR is Wacker. Unless otherwise specified to the contrary, an exemplary form of LSR has a Shore A (or Type A) indentation hardness in the range of about 35 to about 45 as measured using ASTM D2240.

[0477] Polycarbonate: A thermoplastic polymer of bisphenol A carbonate.

[0478] 5.10.1.2 Mechanical Properties

[0479] Resilience: The ability of a material to absorb energy when elastically deformed and to release the energy when unloaded.

[0480] Elasticity: Will release substantially all of the energy when unloaded. Includes, for example, certain siloxanes and thermoplastic elastomers.

[0481] Hardness: The ability of a material itself to resist deformation (e.g. described by Young’s modulus or indentation hardness scales measured on standardized sample dimensions).

[0482] • “Soft” materials can include silicone or thermoplastic elastomers (TPEs) and can deform easily, for example, under finger pressure.

[0483] • “Hard” materials can include polycarbonate, polypropylene, steel, or aluminum and can not deform as easily, for example, under finger pressure.

[0484] Stiffness (or rigidity) of a structure or component: the ability of a structure or component to resist deformation in response to an applied load. The load can be a force or a moment, e.g. compression, tension, bending or torsion. The structure or component can provide different resistance in different directions. The inverse of stiffness is flexibility.

[0485] Soft structure or component: a structure or component that will change shape (e.g. bend) when left to support its own weight for a relatively short time, e.g. 1 second.

[0486] Rigid structure or component: a structure or component that does not substantially change shape when subjected to loads typically encountered in use. An example of such use can be a patient interface being arranged and held in a sealing relation with an entrance to a patient’s airways under a load of e.g. a pressure of about 20 to 30 cmH20.

[0487] As an example, an I-beam can comprise different bending stiffness (resistance to bending loads) in a first direction compared to a second, orthogonal direction. In another example, a structure or component can be soft in a first direction and rigid in a second direction.

[0488] 5.10.2 Breathing cycle

[0489] Apnoea: according to some definitions, an apnoea is considered to occur when the flow drops below a predetermined threshold for a duration of time, e.g. 10 seconds. An obstructive apnoea is considered to occur when some obstruction of the airways does not allow air flow, even when the patient is making efforts. A central apnoea is considered to occur when a respiratory apnoea is detected despite the airways being patent, due to a reduction or absence of respiratory effort. A mixed apnoea is considered to occur when a reduction or absence of respiratory effort coincides with an obstructed airway.

[0490] Breathing frequency: the rate of spontaneous breaths of a patient, which is typically measured in breaths per minute.

[0491] Duty cycle: the ratio of inhalation time, Ti, to total breathing time, Ttot.

[0492] Effort (breathing): the work done by a spontaneous breather in attempting to breathe.

[0493] Exhalation portion of a breathing cycle: the period of time from the start of exhalation flow to the start of inhalation flow.

[0494] Flow limitation: a flow limitation will be considered to be a state in a patient’s breathing where an increase in effort by the patient does not lead to a corresponding increase in flow. A flow limitation can be described as an inspiratory flow limitation in the case where it occurs during the inspiratory portion of a breathing cycle. A flow limitation can be described as an expiratory flow limitation in the case where it occurs during the expiratory portion of a breathing cycle.

[0495] Types of flow-limited inhalation waveforms:

[0496] (i) Flat: has a rise followed by a relatively flat portion followed by a fall.

[0497] (ii) M-shaped: has two local peaks, one at the leading edge and one at the trailing edge, and a relatively flat portion between the two peaks.

[0498] (iii) Chair-shaped: has a single local peak, the peak being at the leading edge, followed by a relatively flat portion.

[0499] (iv) Inverted chair-shaped: has a relatively flat portion followed by a single local peak, the peak being at the trailing edge.

[0500] Hypopnea: According to some definitions, a hypopnea will be considered to be a reduction in flow, rather than a cessation of flow. In one form, a hypopnea is considered to occur when the flow reduces below a threshold rate for a period of time. When a hypopnea is detected due to a reduction in respiratory effort, a central hypopnea is considered to occur. In one form for adults, either of the following can be considered a hypopnea:

[0501] (i) a 30% reduction in patient breathing for at least 10 seconds plus an associated 4% desaturation;

[0502] (ii) a reduction in patient breathing (but less than 50%) for at least 10 seconds with an associated at least 3% desaturation or arousal.

[0503] Hyperpnea: an increase in flow to above normal levels.

[0504] Inspiratory portion of a respiratory cycle: the period of time from the start of inhalation flow to the start of exhalation flow is considered to be the inspiratory portion of a respiratory cycle.

[0505] Open (airway): the degree to which an airway is open or the degree to which an airway is open. An open airway is open. Airway openness can be quantified, for example, with a value of (1) being open and a value of zero (0) being closed (obstructed).

[0506] Positive end-expiratory pressure (PEEP): a pressure above atmospheric pressure that exists in the lungs at the end of exhalation.

[0507] Peak flow (Qpeak): the maximum value of flow during the inspiratory portion of a breath flow waveform.

[0508] ​Breath flow, patient air flow, respiratory air flow (Qr): These terms can be understood to refer to the RPT device's estimate of the breath flow, as opposed to the "true breath flow" or "true respiratory flow", which is the actual breath flow experienced by the patient, typically expressed in litres per minute.

[0509] Tidal volume (Vt): The volume of air inhaled or exhaled during normal breathing when no extra effort is applied. In principle, the inspiratory volume Vi (volume of air inhaled) is equal to the expiratory volume Ve (volume of air exhaled), so a single tidal volume Vt can be defined as equal to either. In practice, the tidal volume Vt is estimated as some combination of the inspiratory volume Vi and the expiratory volume Ve, such as the average.

[0510] (Inspiratory) time (Ti): The duration of the inspiratory portion of a breath flow waveform.

[0511] (Expiratory) time (Te): The duration of the expiratory portion of a breath flow waveform.

[0512] (Overall) time (Ttot): The total duration between the start of an inspiratory portion of one breath flow waveform and the start of the inspiratory portion of the subsequent breath flow waveform.

[0513] Typical recent ventilation: A measure of the central tendency of the ventilation values around which the ventilation Vent recent values tend to cluster over some predetermined time horizon.

[0514] Upper airway obstruction (UAO): Includes partial and total upper airway obstruction. This can be associated with a state of flow limitation in which flow only increases slightly, or even decreases, as the pressure difference across the upper airway increases (Starling resistance behaviour).

[0515] Ventilation (Vent): A measure of the rate of gas exchange by the patient's respiratory system. The measure of ventilation can include one or both of the inspiratory and expiratory flow rates (per unit time). When expressed as a volume per minute, this quantity is often referred to as the "minute ventilation". The minute ventilation is sometimes simply given as a volume and understood to be a volume per minute.

[0516] 5.10.3 Ventilation

[0517] Adaptive servo-ventilator (ASV): A type of servo-ventilator with a variable, rather than a fixed, target ventilation. The variable target ventilation can be learned from some characteristic of the patient, such as a breathing characteristic of the patient.

[0518] Backup rate: A ventilator parameter that determines the minimum respiratory rate (typically expressed in breaths per minute) at which the ventilator will deliver breaths to the patient if not triggered by a spontaneous breath effort.

[0519] Cycle: Termination of the inspiratory phase of the ventilator breath. When the ventilator is delivering breaths to a spontaneously breathing patient, at the end of the inspiratory portion of the breathing cycle, the ventilator is said to cycle to stop delivering breaths.

[0520] Exhalation positive airway pressure (EPAP): The base pressure to which pressure variations within a breath are added to produce the desired interface pressure that the ventilator will attempt to achieve at a given time.

[0521] End-Exhalation Pressure (EEP): The desired interface pressure that the ventilator will try to obtain at the end of the exhalation portion of a breath. If the pressure waveform template Π(Φ) is a zero value at the end of exhalation, i.e., when Φ = 1, Π(Φ) = 0, then the EEP is equal to the EPAP.

[0522] Inspiratory positive airway pressure (IPAP): The maximum desired interface pressure that the ventilator attempts to reach during the inspiratory portion of a breath.

[0523] Pressure Support: A value that indicates the increase in pressure during inspiration by the ventilator over the increase in pressure during expiration by the ventilator, and generally means the difference in pressure between the maximum during inspiration and the base pressure (e.g., PS = IPAP - EPAP). In some cases, pressure support means the difference that the ventilator wants to achieve, not the difference that it actually achieves.

[0524] Servo-ventilator: A ventilator that measures the patient's ventilation and has a target ventilation, and adjusts the pressure support level to bring the patient's ventilation to the target ventilation.

[0525] Spontaneous / timed (S / T): A mode of a ventilator or other device that attempts to detect the start of a breath by a spontaneously breathing patient. However, if the device cannot detect a breath within a predetermined period of time, the device will automatically initiate the delivery of a breath.

[0526] Swing: An equivalent term for pressure support.

[0527] Trigger: Said to be triggered when a ventilator delivers an air breath to a spontaneously breathing patient at the time the patient effort begins the inspiratory portion of the breathing cycle.

[0528] 5.10.4 Patient Interface

[0529] Anti-asphyxia valve (AAV): A component or subcomponent of a mask system that reduces the risk of excessive CO2 rebreathing by the patient by opening to atmosphere in a fail-safe manner.

[0530] Elbow: An elbow is an example of a structure that directs the axis of the airflow travelling through it to change direction through an angle. In one form, the angle can be approximately 90 degrees. In another form, the angle can be greater or less than 90 degrees. An elbow can have a cross-section that is approximately circular. In another form, an elbow can have an elliptical or rectangular cross-section. In certain forms, an elbow can be rotatable relative to a mating component, for example, about 360 degrees. In certain forms, an elbow can be removable from a mating component, for example, via a snap connection. In certain forms, an elbow can be assembled to a mating component via a snap fit during manufacture, but not removable by a patient.

[0531] Frame: A frame will be taken to mean a mask structure that carries the tensile load between two or more connection points to a headgear. A mask frame can be a non-airtight load carrying structure in a mask. However, some forms of mask frame can also be airtight.

[0532] Headgear: Headgear will be taken to mean a form of positioning and stabilising structure designed for use on the head. For example, headgear can comprise a set of one or more support bars, straps and stabilisers configured to position and hold a patient interface in place on the patient's face for the purposes of delivering a therapy. Some straps are formed from a soft, flexible, resilient material, such as a laminate of foam and fabric.

[0533] Membrane: A membrane will be taken to mean a typically thin element that is preferably substantially inextensible but not substantially bend resistant.

[0534] Plenum chamber: A mask plenum chamber will be taken to mean the part of a patient interface that has walls that at least partially enclose a volume of space that in use has air pressurised within it to above atmospheric pressure. A shell can form part of the walls of a mask plenum chamber.

[0535] Seal: Can refer to the noun form of the structure ("seal") and also to the verb form of the effect ("sealing"). Two elements can be structured and / or arranged to'seal' or achieve'sealing' therebetween without the need for a separate'seal' element per se.

[0536] Shell: A shell will be taken to mean a curved and relatively thin structure that has bendable, stretchable and compressible stiffness. For example, a curved structural wall of a mask can be a shell. In some forms, a shell can be faceted. In some forms, a shell can be airtight. In some forms, a shell can not be airtight.

[0537] Stiffener: A stiffener will be taken to mean a structural component designed to increase the bend resistance of another component in at least one direction.

[0538] Supporting strut: A supporting strut shall be considered a structural component designed to increase the resistance to compression of another component in at least one direction.

[0539] Swivel (noun): A subassembly of components configured to rotate about a common axis, preferably independently, preferably at low torque. In one form, a swivel can be configured to rotate through an angle of at least 360 degrees. In another form, a swivel can be configured to rotate through an angle of less than 360 degrees. When used in the context of an air delivery conduit, the subassembly of components preferably includes a pair of mating cylindrical conduits. There can be little or no air leakage from the swivel when in use.

[0540] Lacing (noun): A structure used to resist tension.

[0541] Vent (noun): A structure that allows air flow from inside a mask or conduit to ambient air for clinically effective flushing of exhaled gases. For example, clinically effective flushing can involve a flow of about 10 liters per minute to about 100 liters per minute, depending on the mask design and treatment pressure.

[0542] 5.11 Other Comments

[0543] A portion of the disclosure of this patent document contains material that 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 the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.

[0544] Unless otherwise stated in the context, and where numerical ranges are provided, it is to be understood that every intermediate value of the upper and lower limits of the range, to the tenth of the unit of the lower limit, and any other stated or intervening value in that range, is encompassed within the technology. The upper and lower limits of these intermediate ranges, which can be independently included in the intermediate ranges, are also encompassed within the technology, subject to any specifically excluded limitations within the stated ranges. Where the stated ranges include one or both of the limits, ranges excluding either or both of those included limits are also included within the technology.

[0545] Further, where one or more values are stated in the present document as being implemented as part of the technology, it is to be understood that such values can be approximate, and such values can be used to any suitable number of significant figures to the extent that practical implementation of the technology can permit or require, unless otherwise stated.

[0546] 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 be used in the practice or testing of the present technology, a limited number of the exemplary methods and materials are described herein.

[0547] When particular materials are named herein as being used to construct components, obvious alternative materials of similar properties can be used as substitutes. Moreover, unless specified to the contrary, any and all components described herein are to be understood as being capable of being manufactured, and thus can be manufactured, together or separately.

[0548] It must be noted that, as used herein and in the appended claims, the singular form "a", "an", and "the" include plural referents unless the context clearly dictates otherwise.

[0549] All publications mentioned herein are incorporated herein by reference in their entirety to disclose and describe the methods and / or materials in connection with which the publications are cited. 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 publications. Further, the dates of publication provided can be different from the actual publication dates, which can need to be independently confirmed.

[0550] The terms "comprises" and "comprising" should be interpreted as referring to elements, components, or steps in a non-exclusive manner, referring to the possibility that there are other elements, components, or steps not listed.

[0551] The subject matter headings are included for ease of reference only and are not to be construed as limiting the subject matter described in the respective sections.

[0552] While the technology herein has been described with reference to particular examples, it is to be understood that the examples are illustrative of the principles and application of the technology. In some instances, terminology and symbols can imply specific details that are not required in practice of the described technology. For example, although the terms "first" and "second" can be used, unless otherwise specified, they are not intended to denote any order, but can be used to distinguish different elements. Moreover, although process steps in methods can be described or illustrated in sequence, such sequence is not required. Those skilled in the art will recognize that such sequence can be modified and / or that aspects of it can be performed concurrently or even synchronously.

[0553] It should thus be appreciated that numerous modifications can be made to the exemplary embodiments and that many alternatives can be devised to the details of the present technology without departing from the spirit and scope of the present technology.

[0554] 5.12 List of reference signs

[0555]

[0556]

[0557]

[0558]

[0559]

Claims

1. A device for humidifying breathable airflow, comprising: Processing circuitry; A humidifier, configured to humidify breathable gases; An air delivery tube configured to deliver the humidified breathable gas to a patient interface, the air delivery tube including one or more heating elements extending along at least a portion of the length of the air delivery tube, a sensor configured to measure the characteristics of the humidified breathable gas in the air delivery tube, and a connector having a plurality of electrical contacts. as well as A contact assembly comprising a plurality of electrical device contacts configured to electrically connect the plurality of electrical tube contacts to the processing circuit. The one or more heating elements and the sensor are coupled to the electrical contacts, and the number of electrical device contacts is greater than the number of electrical contacts, such that the electrical contacts are configured to electrically engage only a portion of the electrical device contacts in the operating configuration of the device. The processing circuit is configured to determine the type of air delivery pipe connected to the device based on which of the plurality of electrical device contacts of the contact assembly is connected to the conduit contact in the operating configuration of the device, and based on which of the plurality of electrical device contacts of the contact assembly is not connected to the conduit contact in the operating configuration of the device.

2. The device of claim 1, wherein the processing circuitry is configured to control the operation of the one or more heating elements and the humidifier based on signals received from the sensor.

3. The device of claim 1, wherein the processing circuitry is configured to control the operation of the one or more heating elements and / or the humidifier based on the determined type of air delivery pipe.

4. The device according to any one of claims 1 to 3, wherein the processing circuit is configured to determine the type of the air delivery pipe coupled to the device based on the absence of a connection to the heating element and / or sensor via one or more electrical device contacts.

5. The device according to any one of claims 1 to 3, wherein the contact assembly comprises only four electrical device contacts, a first pair of electrical device contacts configured to be electrically connected to the one or more heating elements, and only one of the second pair of electrical device contacts configured to be electrically connected to the sensor.

6. The device of claim 5, wherein the processing circuitry determines the type of the air delivery pipe connected to the device based on which of the second pair of electrical contacts is connected to the sensor.

7. The device according to any one of claims 1 to 3, wherein the contact assembly comprises only four electrical device contacts, a first pair of the electrical device contacts is configured to be electrically connected to the one or more heating elements, and the processing circuit is configured to determine that a first type of air delivery pipe is connected to the device when a first contact of a second pair of the electrical device contacts is not connected to the sensor, and to determine that a second type of air delivery pipe is connected to the device when a second contact of a second pair of the electrical device contacts is not connected to the sensor.

8. The device according to any one of claims 1 to 3, wherein the contact assembly comprises only four electrical device contacts, and the air delivery conduit comprises only three conduit contacts configured to be coupled to the electrical device contacts.

9. A device for humidifying breathable airflow, comprising: Processing circuitry; A humidifier, configured to humidify breathable gases; An air delivery tube configured to deliver the humidified breathable gas to a patient interface, the air delivery tube including one or more heating elements extending along at least a portion of the length of the air delivery tube, a sensor configured to measure the characteristics of the breathable gas in the air delivery tube, and a connector having a plurality of electrical contacts. as well as A contact assembly includes a plurality of electrical device contacts and a single additional electrical device contact. The plurality of electrical device contacts are configured to electrically connect the plurality of electrical device contacts to the processing circuitry in an operating configuration of the device. The single additional electrical device contact is used to identify the type of air delivery conduit connected to the device. The one or more heating elements and the sensor are coupled to a set of electrical tube contacts configured to be electrically connected to corresponding plurality of electrical device contacts in the operating configuration of the device, and the processing circuit is configured to determine the type of air delivery tube coupled to the device based on electrical characteristics measured by the processing circuit via a single additional electrical device contact of the contact assembly.

10. The device of claim 9, wherein the processing circuitry is configured to control the operation of the one or more heating elements and the humidifier based on signals received from the sensor.

11. The device of claim 9 or 10, wherein the measured characteristics include a voltage set based on a resistive element disposed in the air delivery conduit and connected to the single additional electrical device contact, and an electrical tube contact configured to be electrically connected to the heating element.

12. The device of claim 11, wherein the processing circuitry is configured to determine that a first type of air delivery pipe is connected to the device when the measured characteristic indicates zero volts, and to determine that a second type of air delivery pipe is connected to the device when the measured characteristic indicates a voltage greater than zero.

13. The device of claim 9 or 10, wherein the air delivery conduit includes a resistor or shunt connected between a contact in the group of conduit contacts and a conduit contact configured to be electrically connected to the individual additional electrical device contact.

14. The device of claim 9 or 10, wherein the processing circuitry is configured to control the operation of the one or more heating elements and the humidifier based on the determined type of air delivery pipe.

15. The device of claim 9 or 10, wherein the contact assembly comprises only four electrical device contacts, and the air delivery conduit comprises only three conduit contacts configured to be coupled to the electrical device contacts.

16. A respiratory therapy device, comprising: power supply; Processing system; A pressure generator configured to produce a breathable gas flow; A humidifier configured to store a water supply for humidifying the breathable gas and including a first heating element configured to heat the water supply; An air delivery tube configured to deliver a humidified breathable airflow to a patient, the air delivery tube including a second heating element configured to heat the humidified breathable gas in the air delivery tube and a thermistor configured to generate a temperature signal representing the temperature of the humidified breathable gas in the air delivery tube; A converter configured to generate a flow signal representing the characteristics of the breathable gas flow; as well as A contact assembly configured to mechanically connect the air delivery tube to the humidifier and electrically connect a plurality of main contacts connected to the processing system to a plurality of tube contacts connected to the second heating element and the thermistor, wherein the number of main contacts is greater than the number of tube contacts, such that in the operating configuration of the respiratory therapy device, only a portion of the main contacts are connected to the corresponding tube contacts; The processing system is configured as follows: Based on the signal values ​​received from one or more main contacts, determine which main contact is connected to the second heating element and the thermistor via a tube contact and which main contact is not connected to the second heating element and the thermistor via a tube contact; The type of air delivery pipe connected to the humidifier is determined based on which main contact is connected to the second heating element and the thermistor and which main contact is not connected to the second heating element and the thermistor; as well as Based on the determined pipe type, flow signal and temperature signal, determine (1) a first control signal for controlling the first heating element, (2) a second control signal for controlling the second heating element, and (3) a third control signal for controlling the pressure generator.

17. The respiratory therapy device of claim 16, wherein the contact assembly comprises two main contacts and two additional main contacts, the two main contacts being configured to be electrically connected to two tube contacts connected to the second heating element, the two additional main contacts being configured to be connected to two additional tube contacts, only one of the two additional tube contacts being connected to the thermistor, and the processing system being configured to determine the type of air delivery tube connected to the humidifier based on which of the two additional main contacts is connected to the thermistor via the tube contacts.

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