Methods and devices for treating respiratory disorders

Abstract

Methods, devices, and systems for treating respiratory disorders in a patient are disclosed. The device includes a pressure generator configured to generate an airflow to provide ventilatory assistance to the patient, a transducer configured to generate a flow signal characteristic of the airflow, and a controller. The controller is configured to analyze the flow signal to estimate the patient's inspiratory and expiratory volumes and servo-control the degree of ventilatory assistance to adjust the estimated tidal volume to approach a target tidal volume. The gain of the servo-control depends on the difference between the estimated inspiratory volume and the estimated expiratory volume. The method includes operating the device or system in a similar manner. [Selection diagram] Figure 9

Description

[Technical Field]

[0001] 1 Cross-reference to related applications This application claims the benefit of Australian Provisional Application No. 2017901773, filed May 12, 2017, the contents of which are incorporated herein by reference. 2. Technical Background 2.1 Technology field

[0002] The present technology relates to one or more of screening, diagnosing, monitoring, treating, preventing and ameliorating respiratory-related disorders. The present technology also relates to medical devices or apparatus, and their operation and use. [Background technology]

[0003] 2.2 Description of Related Art 2.2.1 The human respiratory system and its diseases

[0004] The body's respiratory system facilitates gas exchange. The nose and oral cavity form the entrance to a patient's airways.

[0005] These airways contain a series of branching tubes that become narrower, shorter, and more numerous the deeper they travel into the lungs. The lungs' primary function is gas exchange, allowing oxygen from the air to enter the venous blood and carbon dioxide to leave. The trachea divides into the right and left main bronchi, which further divide into the terminal bronchioles. The bronchi constitute conducting airways and do not participate in gas exchange. The airways further divide into respiratory bronchioles and ultimately into alveoli. Gas exchange occurs in the alveolar region of the lung, which is called the respiratory zone. See: "Respiratory Physiology," by John B. West, Lippincott Williams & Wilkins, 9th edition published 2012.

[0006] There is a range of respiratory diseases. Particular diseases can be characterized by particular manifestations such as apnea, hypopnea and hyperpnea.

[0007] Examples of respiratory diseases include obstructive sleep apnea (OSA), Cheyne-Stokes respiration (CSR), respiratory failure, obesity hyperventilation syndrome (OHS), chronic obstructive pulmonary disease (COPD), neuromuscular diseases (NMD), and chest wall diseases.

[0008] Obstructive sleep apnea (OSA) is a form of sleep-disordered breathing (SDB) characterized by episodes of upper airway closure or obstruction during sleep. It results from a combination of an abnormally small upper airway and normal loss of muscle tone in the tongue region, soft palate, and posterior oropharyngeal wall during sleep. This condition causes affected individuals to experience breathing pauses typically lasting 30 to 120 seconds, sometimes 200 to 300 times per night. This can result in excessive daytime sleepiness, which can contribute to cardiovascular disease and brain damage. This condition is common, particularly among middle-aged, overweight men, but patients often experience no symptoms. See U.S. Pat. No. 4,944,310 (Sullivan).

[0009] Cheyne-Stokes respiration (CSR) is another form of sleep-disordered breathing. CSR is a disorder of a patient's respiratory regulator, characterized by alternating periods of waxing and waning ventilation, known as the CSR cycle. CSR is characterized by repeated deoxygenation and reaeration of arterial blood. CSR can be harmful due to repeated hypoxia. In some patients, CSR is associated with recurrent sleep arousals, which can cause severe insomnia, increased sympathetic activity, and increased afterload. See U.S. Patent No. 6,532,959 (Berthon-Jones).

[0010] Respiratory failure is a general term for respiratory disorders that refers to the inability of the lungs to take in enough oxygen or exhale enough CO2 to meet the patient's needs. Respiratory failure can include some or all of the following conditions:

[0011] Patients with respiratory failure (a type of respiratory insufficiency) may experience unusual shortness of breath during exercise.

[0012] Obesity-hypopnea syndrome (OHS) is defined as the combination of severe obesity and chronic awake hypercapnia in the absence of other known causes of hypoventilation. Symptoms include dyspnea, morning headache, and excessive daytime sleepiness.

[0013] Chronic obstructive pulmonary disease (COPD) encompasses any of a group of lower respiratory tract diseases that share certain common characteristics, including increased resistance to air movement, prolonged expiratory phase of breathing, and a decrease in normal lung elasticity. Examples of COPD include emphysema and chronic bronchitis. Causes of COPD include chronic smoking (the primary risk factor), occupational exposure, air pollution, and genetic factors. Symptoms include dyspnea on exertion, chronic cough, and sputum production.

[0014] Neuromuscular disease (NMD) is a broad term encompassing numerous diseases and illnesses that impair muscle function directly through intrinsic muscle pathology or indirectly through neuropathology. Some NMD patients are characterized by progressive muscle impairment, resulting in the inability to walk, wheelchair confinement, difficulty swallowing, respiratory muscle weakness, and ultimately death from respiratory failure. Neuromuscular disorders can be categorized as rapidly progressive or slowly progressive: (i) rapidly progressive disorders, characterized by muscle impairment that worsens over months and leads to death within years (e.g., amyotrophic lateral sclerosis (ALS) and Duchenne muscular dystrophy (DMD) in teenagers); (ii) variable or slowly progressive disorders, characterized by muscle impairment that worsens over years and only modestly reduces life expectancy (e.g., limb-girdle, facioscapulohumeral, and myotonic muscular dystrophy). Symptoms of respiratory failure in NMD include: increasing general weakness, difficulty swallowing, difficulty breathing on exertion and at rest, fatigue, drowsiness, morning headache, and difficulty concentrating and mood changes.

[0015] Chest wall disorders are a group of thoracic deformities that result in ineffective connections between the respiratory muscles and the rib cage. These disorders are primarily characterized by restrictive obstruction and share the potential for long-term hypercapnic respiratory failure. Scoliosis and / or kyphoscoliosis can lead to severe respiratory failure. Symptoms of respiratory failure include: dyspnea on exertion, peripheral edema, orthopnea, recurrent chest infections, morning headache, fatigue, poor sleep quality, and loss of appetite.

[0016] A range of treatments are available to treat or ameliorate these conditions, and preventative treatments for respiratory disease are also available to benefit otherwise healthy individuals. However, these suffer from several deficiencies. 2.2.2 Treatment

[0017] A variety of therapies (e.g., continuous positive airway pressure (CPAP) therapy, non-invasive ventilation (NIV), and invasive ventilation (IV)) are used to treat one or more of the above respiratory disorders.

[0018] Continuous positive airway pressure (CPAP) therapy is used in the treatment of obstructive sleep apnea (OSA). Its mechanism of action is that continuous positive airway pressure acts as a pneumatic splint, for example, by pushing the soft palate and tongue forward or backward against the posterior oropharyngeal wall, thereby preventing closure of the upper airway. Because treatment of OSA with CPAP therapy can be voluntary, patients may choose not to adhere to treatment if they perceive one or more of the following about the device used to deliver the treatment: uncomfortable, difficult to use, expensive, or aesthetically unappealing.

[0019] Non-invasive ventilation (NIV) Supplementary Help ventilation is delivered to the patient through the upper airway to assist the patient in breathing and / or maintain adequate oxygen levels in the body by performing some or all of the respiratory functions. Supplementary Help ventilationis delivered via a non-invasive patient interface. NIV is used to treat CSR and respiratory failure in forms such as OHS, COPD, NMD, and chest wall disorders.

[0020] Invasive ventilation (IV) provides ventilatory support to patients who are no longer able to breathe effectively on their own and can be provided using a tracheostomy tube.

[0021] In some forms, the comfort and effectiveness of these treatments may be improved. 2.2.3 Treatment System

[0022] These treatments may be provided by therapeutic systems or devices. Such systems and devices may also be used to screen, diagnose, or monitor a disease without treating it.

[0023] The treatment system may include a respiratory pressure treatment device (RPT device), an air circuit, a humidifier, a patient interface, and data management. 2.2.3.1 Respiratory Pressure Therapy (RPT) Devices

[0024] Respiratory pressure therapy (RPT) devices can be used individually or as part of a system to deliver one or more of the therapies described above, for example, by activating the device to generate a flow of air delivery to an interface to the airway. This air flow can be pressurized. RPT devices typically include a pressure generator (e.g., an electric blower or compressed gas reservoir) and are configured to supply the air flow to the patient's airway. In some cases, the air flow can be supplied to the patient's airway at positive pressure. The outlet of the RPT device is connected via an air circuit to a patient interface, as described below.

[0025] One known RPT device used to treat sleep-disordered breathing is the S9 Sleep Therapy System (manufactured by ResMed Limited). Another example of an RPT device is a ventilator. The ResMed Elisee® 150 ventilator and ResMed VSIII® ventilator can provide invasive and non-invasive dependent respiratory support suitable for adult or pediatric patients for the treatment of multiple conditions. These ventilators offer volume- and pressure-controlled ventilation modes with single- or dual-limb circuits. 2.2.3.2 Patient Interface

[0026] A patient interface may be used to provide a wearer with an interface to a respiratory appliance, for example, by providing airflow to the airway entrance. Airflow may be provided via a mask to the nose and / or mouth, a tube to the mouth, or a tracheostomy tube to the patient's trachea. Depending on the therapy being applied, the patient interface may form a seal with, for example, an area of ​​the patient's face, thereby facilitating gas delivery at a pressure sufficient to disperse with atmospheric pressure for therapy implementation (e.g., at a positive pressure of about 10 cmH2O relative to atmospheric pressure). In other forms of therapy, such as oxygen delivery, the patient interface may not include a seal sufficient to facilitate delivery of a gas supply to the airways at a positive pressure of about 10 cmH2O. 2.2.3.3 Humidifier

[0027] Delivery of airflow without humidification can lead to dryness of the airway. When a humidifier is used with an RPT device and patient interface, humidified gas is produced, minimizing drying of the nasal mucosa and increasing comfort of the patient's airway. Additionally, in cooler climates, the application of warm air to the facial area surrounding the patient interface generally provides more comfort than cool air. 2.2.3.4 Data Management

[0028] For clinical reasons, data may be obtained to determine whether a patient prescribed respiratory therapy is "compliant" (e.g., whether the patient adheres to one or more "compliance rules" with their RPT device). An example of a compliance rule for CPAP therapy may require a patient to use the RPT device for at least four hours per night for at least 21 days out of 30 consecutive days to be considered compliant. To determine patient compliance, a provider of the RPT device (e.g., a healthcare provider) may manually obtain data describing the patient's treatment with the RPT device, calculate usage rates over a given period, and compare this to the compliance rules. Once the healthcare provider determines that the patient has used their RPT device in accordance with the compliance rules, the healthcare provider may notify a third party that the patient is compliant.

[0029] There may be other aspects of patient care that benefit from communication of treatment data to third parties or external systems. 2.2.3.5 Ventilation technology

[0030] Some forms of treatment systems may include a vent to push out exhaled carbon dioxide, which may allow gas flow from an interior space of the patient interface (e.g., a plenum chamber) to an exterior of the patient interface (e.g., ambient). 3. Brief description of the technology

[0031] The present technology relates to the provision of medical devices for use in screening, diagnosing, monitoring, ameliorating, treating or preventing respiratory diseases, which medical devices have one or more of improved comfort, cost, effectiveness, ease of use and manufacturability.

[0032] A first aspect of the present technology relates to devices used in the screening, diagnosis, monitoring, amelioration, treatment or prevention of respiratory disease.

[0033] Another aspect of the present technology relates to methods used in the screening, diagnosis, monitoring, amelioration, treatment or prevention of respiratory disorders.

[0034] One form of the present technology includes an apparatus for treating respiratory disorders using a safe volume servo ventilation mode, where the gain of the pressure support servo control is based on the difference between an estimated inspiratory volume and an estimated expiratory volume.

[0035] In accordance with one aspect of the present technology, there is provided an apparatus for treating respiratory disorders in a patient. Supplementary Help ventilation a pressure generator configured to generate an airflow to provide a pressure of 100 psi, a transducer configured to generate a signal indicative of a characteristic of the airflow, and a controller, the controller analyzing the signal to estimate the inhaled and exhaled volumes of the patient's breath and to adjust the estimated tidal volume to approach a target tidal volume. Supplementary Help ventilation and servo-controlling the degree of .times. ...

[0036] In one example of this aspect, the gain decreases with increasing difference between the estimated inhaled and exhaled volumes. In a further example, the gain depends on the difference between the estimated inhaled and exhaled volumes relative to the estimated tidal volume. Furthermore, the gain depends on the absolute magnitude of the difference between the estimated inhaled and exhaled volumes.

[0037] In another example of this embodiment, Supplementary Help ventilation The degree of Supplementary Help ventilation This is pressure assistance.

[0038] In accordance with a further aspect of the present technology, Supplementary Help ventilationA method is provided for operating a respiratory therapy device configured to generate an airflow to provide a target tidal volume, the method including: measuring a characteristic of the airflow with a transducer, analyzing the measured characteristic in a controller to estimate the patient's inhaled and exhaled volumes, calculating a gain in the controller based on the difference between the estimated inhaled and exhaled volumes, and servo-controlling the respiratory therapy device by the controller using the calculated gain to adjust the estimated tidal volume for the patient toward a target tidal volume.

[0039] In one example of this aspect, the gain depends on the difference between the estimated inhaled and exhaled volumes relative to the estimated tidal volume. In another example, the gain depends on the absolute magnitude of the difference between the estimated inhaled and exhaled volumes. Supplementary Help ventilation The degree of Supplementary Help ventilation This is pressure assistance.

[0040] In accordance with a further aspect of the present technology, there is provided a system for treating respiratory disorders in a patient. Supplementary Help ventilation means for generating a signal indicative of the airflow characteristic; means for analyzing the signal to estimate the inhaled and exhaled volumes of the patient's breath; and means for adjusting the estimated tidal volume to approximate a target tidal volume. Supplementary Help ventilation and means for servo-controlling the degree of the estimated inhalation volume, the gain of which depends on the difference between the estimated inhalation volume and the estimated exhalation volume.

[0041] In accordance with a further aspect of the present technology, there is provided an apparatus for treating respiratory disorders in a patient. Supplementary Help ventilationThe patient breathing apparatus includes a blower configured to deliver an air supply that provides a response to a patient's breathing pattern, a transducer configured to generate a signal indicative of a characteristic of the air supply, and a controller configured to analyze the signal to estimate an inhaled and exhaled volume of the patient's breath and to adjust a servo control gain based on a difference between the estimated inhaled and exhaled volumes.

[0042] In one example of this embodiment, the controller adjusts the servo control gain such that the gain decreases with increasing difference between the estimated inhaled volume and the estimated exhaled volume. In another example, adjusting the servo control gain decreases the rate of adjustment of the pressure support of the air supply. In another example, the controller is configured to adjust the servo control gain if the difference is 20% or greater, or is further configured to adjust the servo control gain to a default value if the difference returns to a value below 20%.

[0043] The described methods, systems, devices, and apparatus may be implemented to enable improved functionality in a processor (e.g., a processor in a special purpose computer, a respiratory monitor, and / or a respiratory treatment device). Further, the described methods, systems, devices, and apparatus enable advancements in the art of automated management, monitoring, and / or treatment of respiratory conditions (e.g., sleep disordered breathing).

[0044] Of course, some of the above aspects may form sub-aspects of the present technology, and various one of the sub-aspects, aspects and / or examples may be combined in various ways to form further aspects or sub-aspects of the present technology.

[0045] Other features of the present technology will become apparent in light of the information contained in the following detailed description, abstract, drawings, and claims. [Brief explanation of the drawings]

[0046] 4 Brief description of the drawings The present technology is illustrated by way of example and not limitation in the accompanying drawings, in which like reference numerals include like elements: 4.1 Treatment System [Figure 1] 1 shows a system including a patient 1000 wearing a patient interface 3000. The patient interface 3000 takes the form of a full face mask and receives a supply of air at positive pressure from an RPT device 4000. Air from the RPT device is humidified by a humidifier 5000 and travels along an air circuit 4170 to the patient 1000. The patient is sleeping in a lateral sleeping position. 4.2 Respiratory System and Facial Anatomy [Figure 2] Figure 2 shows an overview of the human respiratory system, including the nose and oral cavity, larynx, vocal folds, esophagus, trachea, bronchi, lungs, alveolar sacs, heart, and diaphragm. 4.3 Patient Interface [Figure 3] Figure 3 shows a patient interface in the form of a nasal mask in accordance with one form of the present technology. 4.4 RPT Device [Figure 4A] 4 shows an RPT device 4000 in accordance with one form of the present technology. [Figure 4B] 1 is a schematic diagram of an air circuit of an RPT device 4000 in accordance with one form of the present technology. Upstream and downstream directions are indicated relative to the blower and patient interface. Regardless of the actual flow direction at any particular moment, the blower is defined as being upstream of the patient interface, and the patient interface is defined as being downstream of the blower. Items located in the pneumatic path between the blower and the patient interface are downstream of the blower and upstream of the patient interface. [Figure 4C] FIG. 40 is a schematic diagram of the electrical components of an RPT device 4000 in accordance with one aspect of the present technology. [Figure 4D] 4D is a schematic diagram of an algorithm executed in an RPT device in accordance with one form of the present technology. 4.5 Humidifier [Figure 5A] FIG. 5A is an isometric view of a humidifier in accordance with one form of the present technology. [Figure 5B]5B is an isometric view of a humidifier in accordance with one form of the present technology, showing the humidifier reservoir 5110 removed from the humidifier reservoir dock 5130. 4.6 Respiratory Waveforms [Figure 6] Figure 6 shows a model of a typical human breathing waveform during sleep. 4.7 Breathing Pressure Treatment Mode [Figure 7A] FIG. 7A is a graph illustrating undesirable behavior of pressure assist during a sudden leak change in conventional safe volume mode. [Figure 7B] FIG. 7B is a graph showing pressure assist behavior during a sudden leak change in safe volume mode in accordance with one form of the present technology. [Figure 8] FIG. 8 is a graph illustrating the adjustment of servo control gain in safe volume mode as a function of the relative difference between inhaled and exhaled volumes. [Figure 9] FIG. 9 is a flow chart outlining a method for adjusting servo controller gains in a respiratory device. DETAILED DESCRIPTION OF THE INVENTION

[0047] 5 Detailed Description of the Embodiments of the Present Technology Before describing the present technology in further detail, it is to be understood that the present technology is not limited to the specific embodiments described herein, which may vary. It is also to be understood that the terminology used in the present disclosure is for the purpose of describing the specific embodiments described herein, and is not intended to be limiting.

[0048] The following description is provided in connection with various embodiments that may share one or more common characteristics and / or features. It should be understood that one or more features of any one embodiment may be combined with one or more features of another embodiment or other embodiments. In addition, any single feature or combination of features in any of these embodiments may constitute an additional embodiment. 5.1 Treatment

[0049] In one form, the present technology includes a method of treating a respiratory disorder, the method including applying positive pressure to the entrance of the airways of a patient 1000.

[0050] In certain embodiments of the present technology, a supply of air at positive pressure is provided to the patient's nasal passages via one or both nostrils.

[0051] In certain embodiments of the present technology, mouth breathing is restricted, limited or prevented. 5.2 Treatment System

[0052] In one form, the present technology includes an apparatus or device for the treatment of disordered breathing. The apparatus or device may include an RPT device 4000 that supplies pressurized air to a patient 1000 via an air circuit 4170 to a patient interface 3000, for example as shown in FIG. 5.3 Patient Interface

[0053] A non-invasive patient interface 3000 in accordance with one aspect of the present technology, as shown in, for example, FIG. 3 , includes the following functional features: a seal-forming structure 3100, a plenum chamber 3200, a positioning and stabilizing 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, the functional features may be provided by one or more physical components. In some forms, a single physical component may provide one or more functional features. In use, the seal-forming structure 3100 is positioned to surround the entrance to the patient's airways to facilitate the delivery of air at positive pressure to the airways. 5.4 RPT Device

[0054] An RPT device 4000 according to one aspect of the present technology includes mechanical, pneumatic, and / or electrical components and is configured to execute one or more algorithms 4300 (e.g., any of the methods described herein, in whole or in part). The RPT device 4000 may be configured to generate an airflow that is delivered to a patient's airway for treatment of, for example, one or more of the respiratory conditions described anywhere herein. Figures 4A-4D are schematic diagrams that illustrate examples of components or may include the RPT device 4000.

[0055] The RPT device may have an outer housing 4010. The outer housing 4010 is formed by two portions: an upper portion 4012 and a lower portion 4014. Additionally, the outer housing 4010 may include one or more panel(s) 4015. The RPT device 4000 includes a chassis 4016 that supports one or more internal components of the RPT device 4000. The RPT device 4000 may include a handle 4018.

[0056] The air pressure path of the pneumatic RPT device 4000 may include one or more air circuit items (e.g., an inlet air filter 4112, an inlet muffler 4122, a pressure generator 4140 (e.g., a blower 4142) capable of supplying air at positive pressure, an outlet muffler 4124) and one or more transducers 4270 (e.g., a pressure sensor 4272 and a flow sensor 4274).

[0057] One or more of the air path items may be located within a removable, unitary structure called a pneumatic block 4020. The pneumatic block 4020 may be located within the outer housing 4010. In one form, the pneumatic block 4020 is supported by or formed as part of the chassis 4016.

[0058] 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, the RPT device 4000 can include more than one PCBA 4202. 5.4.1 RPT Device Mechanical and Pneumatic Components

[0059] The RPT device may include one or more of the following components in an integral unit: In an alternative, one or more of the following components may be arranged as their own separate units. 5.4.1.1 Air filters

[0060] An RPT device in accordance with one form of the present technology may include an air filter 4110 or multiple air filters 4110.

[0061] In one form, the inlet air filter 4112 is located at the beginning of the air pressure path upstream of the pressure generator 4140 .

[0062] In one form, an outlet air filter 4114 (eg, an antibacterial agent) is located between the outlet of the pneumatic block 4020 and the patient interface 3000. 5.4.1.2 Mufflers

[0063] An RPT device in accordance with one form of the present technology may include a muffler 4120 or multiple mufflers 4120.

[0064] In one form of the present technology, an inlet muffler 4122 is positioned above a pressure generator 4140 in the pneumatic path.

[0065] In one form of the present technology, the outlet muffler 4124 is positioned in the pneumatic path between the pressure generator 4140 and the patient interface 3000. 5.4.1.3 Pressure generator

[0066] In one form of the present technology, the pressure generator 4140 that generates the air flow or supply at positive pressure is a controllable blower 4142. For example, the blower 4142 may include a brushless DC motor 4144 with one or more impellers housed within a blower housing, for example, in a volute. The blower may deliver the air supply at a rate of, for example, up to about 120 liters / minute, at a positive pressure ranging from about 4 cmH2O to about 20 cmH2O, or in other forms up to about 30 cmH2O. The blower may be described in any one of the following patents or patent applications, which are incorporated herein by reference in their entirety: U.S. Patent No. 7,866,944; U.S. Patent No. 8,638,014; U.S. Patent No. 8,636,479; and PCT Patent Application Publication WO 2013 / 020167.

[0067] The pressure generator 4140 is under the control of the therapy device controller 4240 .

[0068] In other forms, pressure generator 4140 can be a piston-driven pump, a pressure regulator connected to a high pressure source (eg, a compressed air reservoir), or a bellows. 5.4.1.4 Converters

[0069] The transducer may be internal to the RPT device or external to the RPT device. An external transducer may, for example, be located on the air circuit or form part of the air circuit (e.g., a patient interface). An external transducer may take the form of a non-contact sensor (e.g., a Doppler radar motion sensor that transmits or moves data RPT device).

[0070] In one form of the present technology, one or more transducers 4270 may be positioned upstream and / or downstream of the pressure generator 4140. The one or more transducers 4270 may be constructed and arranged to generate a signal indicative of a characteristic of the airflow (e.g., flow rate, pressure, or temperature at that point in the pneumatic path).

[0071] In one form of the present technology, one or more transducers 4270 may be positioned proximate the patient interface 3000.

[0072] In one form, the signal from the converter 4270 may be filtered (eg, by low-pass, high-pass, or band-pass filtering). 5.4.1.4.1 Flow Sensor

[0073] A flow sensor 4274 according to the present technology may be based on a differential pressure transducer (eg, an SDP600 series differential pressure transducer from SENSIRION).

[0074] In one form, a signal indicative of the flow rate from the flow sensor 4274 is received by the central controller 4230. 5.4.1.4.2 Pressure Sensors

[0075] A pressure sensor 4272 according to the present technology can be placed in fluid communication with the pneumatic path. One 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.

[0076] In one form, the signal from the pressure sensor 4272 is received by the central controller 4230. 5.4.1.4.3 Motor Speed ​​Converter

[0077] In one form of the present technology, a motor speed transducer 4276 may be used to determine the rotational speed of the motor 4144 and / or blower 4142. A motor speed signal from the motor speed transducer 4276 may be provided to the therapy device controller 4240. The motor speed transducer 4276 may be, for example, a speed sensor (e.g., a Hall effect sensor). 5.4.1.5 Anti-spillback valves

[0078] In one form of the present technology, an anti-spillback valve 4160 may be located between the humidifier 5000 and the pneumatic block 4020. The anti-spillback valve is constructed and positioned to reduce the risk of water flowing upstream from the humidifier 5000 (e.g., to the blower motor 4144). 5.4.2 RPT Device Electrical Components 5.4.2.1 Power supply

[0079] The power supply 4210 may be located inside or outside the external housing 4010 of the RPT device 4000.

[0080] In one form of the present technology, the power supply 4210 powers only the RPT device 4000. In another form of the present technology, power is provided from the power supply 4210 to both the RPT device 4000 and the humidifier 5000. 5.4.2.2 Input Devices

[0081] In one form of the present technology, the RPT device 4000 includes one or more input devices 4220 in the form of buttons, switches, or dials to allow a human to interact with the device. The buttons, switches, or dials may be physical or software devices accessible via a touchscreen. The buttons, switches, or dials may be physically connected to the external housing 4010 in one form, or may communicate wirelessly with a receiver electrically connected to the central controller 4230 in another form.

[0082] In one form, input device 4220 may be constructed and arranged to allow a human to select values ​​and / or menu options. 5.4.2.3 Central Controller

[0083] In one form of the present technology, the central controller 4230 is one or more processors suitable for controlling the RPT device 4000.

[0084] Suitable processors may include x86 INTEL processors, processors based on the ARM® Cortex®-M processor from ARM Holdings (e.g., the S®32 series of microcontrollers from ST Micro Electronics). In certain alternative forms of the present technology, 32-bit RISC CPUs (e.g., the STR9 series microcontrollers from ST Micro Electronics) or 16-bit RISC CPUs (e.g., processors from the MSP430 family of microcontrollers manufactured by Texas Instruments) may also be suitable.

[0085] In one form of the present technology, the central controller 4230 is a dedicated electronic circuit.

[0086] In one form, the central controller 4230 is an application specific integrated circuit. In another form, the central controller 4230 includes discrete electronic components.

[0087] The central controller 4230 may be configured to receive input signals from one or more transducers 4270, one or more input devices 4220 and the humidifier 5000.

[0088] The central controller 4230 may be configured to provide output signal(s) to one or more of the output device 4290, the therapy device controller 4240, the data communication interface 4280, and the humidifier 5000.

[0089] In some forms of the present technology, the central controller 4230 is configured to implement one or more methods described herein (e.g., one or more algorithms 4300 expressed as a computer program stored in a non-transitory computer-readable recording medium (e.g., memory 4260)). In some forms of the present technology, the central controller 4230 may be integrated with the RPT device 4000. However, in some forms of the present technology, some methods may be performed by a remotely located device. For example, the remotely located device may determine ventilator control settings or detect respiratory-related events through analysis of recorded data (e.g., from any of the sensors described herein). 5.4.2.4 Clock

[0090] The RPT device 4000 may include a clock 4232 connected to the central controller 4230 . 5.4.2.5 Therapy Device Controller

[0091] In one form of the present technology, the therapy device controller 4240 is a therapy control module 4330 and forms part of the algorithm 4300 executed by the central controller 4230.

[0092] In one form of the present technology, the therapy device controller 4240 is a dedicated motor control integrated circuit. For example, in one form, the MC33035 brushless DC motor controller manufactured by ONSEMI is used. 5.4.2.6 Protection circuit

[0093] The one or more protection circuits 4250 according to the present technology may include electrical protection circuits, temperature and / or pressure safety circuits. 5.4.2.7 Memory

[0094] In accordance with one form of the present technology, the RPT device 4000 includes memory 4260 (e.g., non-volatile memory). In some forms, the memory 4260 may include battery-powered static RAM. In some forms, the memory 4260 may include volatile RAM.

[0095] Memory 4260 may be located on PCBA 4202. Memory 4260 may take the form of EEPROM or NAND flash.

[0096] Additionally or alternatively, the RPT device 4000 includes removable memory 4260 (eg, a memory card made in accordance with the Secure Digital (SD) standard).

[0097] In one form of the present technology, the memory 4260 functions as a non-transitory computer-readable storage medium on which are recorded computer program instructions (e.g., one or more algorithms 4300) embodying one or more of the methods described herein. 5.4.2.8 Data communication systems

[0098] In one form of the present technology, a data communications interface 4280 is provided and connected to the central controller 4230. The data communications interface 4280 may be connectable to a remote external communications network 4282 and / or a local external communications network 4284. The remote external communications network 4282 may be connectable to a remote external device 4286. The local external communications network 4284 may be connectable to a local external device 4288.

[0099] 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 may include an integrated circuit or processor.

[0100] In one form, remote external communications network 4282 is the Internet. Data communications interface 4280 may use wired communications (e.g., via Ethernet or fiber optics) or may use wireless protocols (e.g., CDMA, GSM, LTE) to connect to the Internet.

[0101] In one form, the local external communications network 4284 uses one or more communications standards (eg, Bluetooth or Consumer Infrared Protocol).

[0102] In one form, the remote external device 4286 is one or more computers (e.g., a cluster of networked computers). In one form, the remote external device 4286 may be a virtual computer rather than a physical computer. In either case, such a remote external device 4286 may be accessible by an appropriately authorized person (e.g., a clinician).

[0103] The local external device 4288 may be a personal computer, a mobile phone, a tablet or a remote control. 5.4.2.9 Optional displays and output devices, including alarms

[0104] Output devices 4290 according to the present technology may take the form of one or more of visual, audio and tactile units. The visual display may be a liquid crystal display (LCD) or a light emitting diode (LED) display. 5.4.2.9.1 Display Driver

[0105] 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 those characters, symbols or images. 5.4.2.9.2 Display

[0106] Display 4294 is configured to visually display characters, symbols, or images in response to commands received from display driver 4292. For example, display 4294 may be an eight-segment display, in which case display driver 4292 converts each character or symbol (e.g., the digit "0") into eight logic signals indicating which of the eight segments should be activated to display the particular character or symbol. 5.4.3 RPT Device Algorithm

[0107] As noted above, in some forms of the present technology, the central controller 4230 may be configured to embody one or more algorithms 4300 expressed as a computer program stored in a non-transitory computer-readable storage medium (e.g., memory 4260). The algorithms 4300 are typically grouped into groups called modules. 5.4.3.1 Pre-processing module

[0108] A pre-processing module 4310 in accordance with one form of the present technology receives as input a signal from a transducer 4270 (e.g., a flow sensor 4274 or a pressure sensor 4272) and performs one or more process steps to calculate one or more output values ​​that are used as inputs to another module (e.g., a therapy engine module 4320) and may be depicted, for example, as shown in FIG. 4D.

[0109] In one form of the present technology, the output values ​​include interface or mask pressure Pm, respiratory flow Qr, and leak flow Ql.

[0110] In various forms of the present technology, the pre-processing module 4310 includes one or more of the following algorithms: pressure compensation 4312, ventilation flow estimation 4314, leak flow estimation 4316, and respiratory flow estimation 4318. 5.4.3.1.1 Pressure compensation

[0111] In one form of the present technology, a pressure compensation algorithm 4312 receives as an input a signal indicative of the pressure in the pneumatic path proximal to the outlet of the pneumatic block. The pressure compensation algorithm 4312 estimates the pressure drop through the pneumatic circuit 4170 and provides as an output the estimated pressure Pm in the patient interface 3000. 5.4.3.1.2 Estimation of ventilation flow rate

[0112] In one form of the present technology, an airflow estimation algorithm 4314 receives as input an estimated pressure Pm in the patient interface 3000 and estimates the airflow Qv of air out of the vent 3400 in the patient interface 3000. 5.4.3.1.3 Estimation of leakage flow rate

[0113] In one form of the present technology, a leak flow estimation algorithm 4316 receives as input the total flow Qt and the ventilation flow Qv and provides as output an estimate of the leak flow Ql, hi one form, the leak flow estimation algorithm estimates the leak flow Ql by calculating the average difference between the total flow Qt and the ventilation flow Qv over a period long enough to include several respiratory cycles (e.g., about 10 seconds).

[0114] In one form, the leak flow estimation algorithm 4316 provides a leak flow Ql as an output and receives as inputs the total flow Qt, ventilation flow Qv, and estimated pressure Pm in the patient interface 3000 by calculating the 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 low-pass filtered quotient of the non-ventilated flow equal to the difference between the total flow Qt and the ventilation flow Qv and the low-pass filtered square root of the pressure Pm, with the low-pass filter time constant having a value sufficient to include several respiratory cycles (e.g., about 10 seconds). The leak flow Ql may be estimated as a function of the product of the leak conductance and the pressure Pm.

[0115] A sudden leak change is a change on a time scale shorter (i.e., on the order of a respiratory cycle or less) than the time scale that the leak flow estimation algorithm 4316 can keep up with from the beginning. In certain treatment modes, such sudden leak changes require special handling, as described below. 5.4.3.1.4 Respiratory flow estimation

[0116] In one form of the present technology, the respiratory flow estimation algorithm 4318 receives as inputs the total flow Qt, the ventilation flow Qv and the leak flow Ql and estimates the respiratory flow Qr of air to the patient by subtracting the ventilation flow Qv and the leak flow Ql from the total flow Qt. 5.4.3.2 Treatment Engine Module

[0117] In one form of the present technology, the therapy engine module 4320 receives as inputs one or more of the pressure in the patient interface 3000, Pm, and the respiratory flow of air to the patient, Qr, and provides one or more therapy parameters as outputs.

[0118] In one form of the present technology, the treatment parameter is a treatment pressure, Pt.

[0119] In one form of the present technology, the therapy parameters are one or more of the amplitude of pressure change, base pressure, and target tidal volume.

[0120] In various embodiments, the therapy engine module 4320 includes one or more of the following algorithms: phase determination 4321, waveform determination 4322, tidal volume estimation 4323, and therapy parameter determination 4329. 5.4.3.2.1 Phase Determination

[0121] In one form of the present technology, the RPT device 4000 may determine the respiratory phase.

[0122] In one form of the present technology, a phase determination algorithm 4321 receives as input a signal indicative of respiratory flow Qr and provides as output Π the phase of the patient's 1000 current respiratory cycle.

[0123] In some forms, the phase output Π, known as discrete phase determination, is a discrete variable. One implementation of discrete phase determination results in a binary phase output Π with a value of inspiration or expiration. This value is represented, for example, as 0 and 0.5 revolutions when the onset of spontaneous inspiration and expiration, respectively, is detected. The RPT device 4000 that "triggers" and "cycles" effectively performs discrete phase determination because the trigger and cycle points are the instants at which the phase changes from inspiration to inspiration and inspiration to expiration, respectively. In one implementation of binary phase determination, the phase output Φ is determined to have a discrete value of 0 (thereby "trigging" the RPT device 4000) when respiratory flow Qr has a value greater than a positive threshold, and a discrete value of 0.5 revolutions (thereby "cycling" the RPT device 4000) when respiratory flow Qr has a value greater than a negative threshold. The inspiration time Ti and expiration time Te may be typical values ​​estimated over many respiratory cycles of the time spent with phase Φ equal to 0 (indicating inspiration) and 0.5 (indicating expiration), respectively.

[0124] Another implementation of the discrete phase determination provides a three-valued phase output Φ with one of the following values: inspiration, pause during inspiration, and expiration.

[0125] In other forms, the phase output Φ, known as continuous phase determination, is a continuous variable, varying, for example, between 0 and 1 revolution or 0 and 2Φ radians. An RPT device 4000 with continuous phase determination may trigger and cycle when the continuous phase reaches 0 and 0.5 revolutions, respectively. In one implementation of continuous phase determination, the phase Φ, as well as the inspiration time Ti and expiration time Te, are first estimated separately from the respiratory flow Qr as described above. The continuous phase Φ at any hypothetical instant is then determined as half the fraction of inspiration time Ti that has elapsed since the previous trigger instant or 0.5 revolutions plus the fraction of expiration time Te that has elapsed since the previous cycle instant (whichever is more recent). 5.4.3.2.2 Waveform determination

[0126] In one form of the present technology, the therapy parameter determination algorithm 4329 provides a nearly constant therapy pressure throughout the patient's respiratory cycle.

[0127] In another form of the present technology, the therapy control module 4330 controls the pressure generator 4140 to provide a therapy pressure Pt that varies as a function of the phase Φ of the patient's respiratory cycle according to a waveform template Π(Φ).

[0128] In one form of the present technology, the waveform determination algorithm 4322 provides a waveform template Π(Φ) having values ​​in the range [0, 1] for the domain of phase values ​​Φ provided by the phase determination algorithm 4321 to be used by the treatment parameter determination algorithm 4329.

[0129] In one embodiment, suitable for a discrete or continuous phase, the waveform template Π(Φ) is a square wave template having a value of 1 for phase values ​​up to 0.5 revolutions and a value of 0 for phase values ​​above 0.5 revolutions. In one embodiment, suitable for a continuous phase, the waveform template Π(Φ) includes two smoothly curved sections (i.e., a smoothly curved (e.g., raised cosine) rise from 0 to 1 for phase values ​​up to 0.5 revolutions, and a smoothly curved (e.g., exponential) fall from 1 to 0 for phase values ​​above 0.5 revolutions). In one embodiment, suitable for a continuous phase, the waveform template Π(Φ) is based on a square wave, but has a smooth rise from 0 to 1 for phase values ​​up to a "rise time" below 0.5 revolutions, and a smooth fall from 1 to 0 for phase values ​​within a "fall time" after 0.5 revolutions, with a "fall time" below 0.5 revolutions.

[0130] In some forms of the present technology, the waveform determination algorithm 4322 selects a waveform template Π(Φ) from a library of waveform templates depending on the settings of the RPT device. Each waveform template Π(Φ) in the library may be provided as a lookup table value Π for a phase value Φ. In other forms, the waveform determination algorithm 4322 calculates the waveform template Π(Φ) "on the fly" using a predetermined functional form, perhaps parameterized by one or more parameters (e.g., the time constant of an exponential curve portion). The parameters of the functional form may be predetermined or may depend on the current state of the patient 1000.

[0131] In some forms of the present technology suitable for the discrete binary phases of inspiration (Φ=0 revolutions) or expiration (Φ=0.5 revolutions), the waveform determination algorithm 4322 calculates the waveform template Π "on the fly" as a function of the discrete phase Φ and 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 parts (inspiration and expiration) as follows:

number

[0132] Here, Π i (t) and Π e (t) are the inspiratory and expiratory portions of the waveform template Π(Φ,t). In one such embodiment, the inspiratory portion Π i (t) is a smooth rise from 0 to 1 parameterized by the rise time, Π e (t) is a smooth decline from 1 to 0 parameterized by the decline time. 5.4.3.2.3 Tidal volume estimation

[0133] In some forms of the present technology, the central controller 4230 runs one or more tidal volume estimation algorithms 4323 for estimating tidal volume using values ​​returned from one or more of the other algorithms in the therapy engine module 4320.

[0134] In one form of the present technology, a tidal volume estimation algorithm 4323 receives as input a signal indicative of the respiratory flow Qr and phase Φ determined by the phase determination algorithm 4321, and calculates the tidal volume V of the most recent breath. T The tidal volume V is returned as an estimate. TQr can be estimated as the inspired (tension) volume during a breath, Vi, the expired (tension) volume during a breath, or some combination (e.g., mean or average) of the two. The inspired volume, Vi, can be estimated as the integral of the respiratory flow, Qr, over the inspiratory portion of the breath (indicated by a phase φ less than 0.5). The expired volume, Ve, can be estimated as the integral of the respiratory flow, Qr, over the expiratory portion of the breath (indicated by a phase φ greater than or equal to 0.5). 5.4.3.2.4 Determining Treatment Parameters

[0135] In some forms of the present technology, the central controller 4230 executes one or more treatment parameter determination algorithms 4329 for determining one or more treatment parameters using values ​​returned from one or more of the other algorithms in the treatment engine module 4320.

[0136] In one form of the present 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 following equation:

number

[0137] where: ● A is the amplitude, ● Π(Φ, t) is the waveform template value (ranging from 0 to 1) at the current value of phase Φ and time t; ● P0 is the base pressure.

[0138] If the waveform determination algorithm 4322 provides the waveform template Π(Φ, t) as a lookup table of values ​​Φ indexed by phase, the treatment parameter determination algorithm 4329 applies equation (1) by locating the closest lookup table entry to the current value Φ of the phase returned from the phase determination algorithm 4321 or by interpolating between two entries that span the current value Φ of the phase.

[0139] The values ​​of amplitude A and base pressure P0 may be set by the treatment parameter determination algorithm 4329 depending on the selected respiratory pressure treatment mode. 5.4.3.3 Treatment Control Module

[0140] The therapy control module 4330 according to one aspect of the present technology receives as input therapy parameters from the therapy parameter determination algorithm 4329 of the therapy engine module 4320 and controls the pressure generator 4140 to deliver airflow from the pressure generator 4140 in accordance with these therapy parameters.

[0141] In one form of the present technology, the treatment parameter is a treatment pressure Pt, and the treatment control module 4330 controls the pressure generator 4140 to deliver an airflow such that the mask pressure Pm at the patient interface 3000 is equal to the treatment pressure Pt. 5.4.3.4 Fault Condition Detection

[0142] In one form of the present technology, the central controller 4230 executes one or more methods 4340 for detecting a fault condition. The fault condition detected by the one or more methods 4340 may include at least one of the following: ● Power outage (no power or power shortage) ● Converter failure detection ● Unable to detect the presence of a component ● Operating parameters are outside the recommended range (e.g., pressure, flow, temperature, PaO2) • Failure of test alerts to produce detectable warning signals.

[0143] When a fault condition is detected, the corresponding algorithm 4340 signal the presence of the fault by one or more of the following: ● Initiation of audible, visual and / or kinetic (e.g., vibration) warnings. ● Sending messages to external devices Incident logging 5.5 Air Circuit

[0144] An air circuit 4170, according to one aspect of the present technology, is a conduit or tube constructed and arranged such that, in use, air flow travels between two components (e.g., the RPT device 4000 and the patient interface 3000).

[0145] In particular, the air circuit 4170 may be fluidly connected to the outlet of the pneumatic block 4020 and the patient interface. The air circuit may be referred to as an air delivery tube. In some cases, there may be separate limbs of the circuit for inhalation and exhalation. In other cases, a single limb air circuit is used. 5.6 Humidifier

[0146] In one form of the present technology, a humidifier 5000 is provided (for example as shown in FIG. 5A) for changing the absolute humidity of air or gas to be delivered to a patient relative to ambient air. Typically, the humidifier 5000 is used to increase the absolute humidity (relative to ambient air) and increase the temperature of the air stream before delivery to the patient's airways.

[0147] The humidifier 5000 may include a humidifier reservoir 5110, a humidifier inlet 5002 for receiving an airflow, and a humidifier outlet 5004 for delivering a humidified airflow. In some forms, such as shown in Figures 5A and 5B, the inlet and outlet of the humidifier reservoir 5110 may be the humidifier inlet 5002 and the humidifier outlet 5004, respectively. The humidifier 5000 may further include a humidifier base 5006. The humidifier base 5006 may be adapted to receive the humidifier reservoir 5110 and may include a heating element 5240. 5.7 Respiratory waveform

[0148] Figure 6 shows a model of a typical human respiratory waveform during sleep. The horizontal axis is time, and the vertical axis is respiratory flow. Because parameter values ​​can vary, a typical breath may have the following approximate values: tidal volume, Vt, 0.5 L; inspiratory time, Ti, 1.6 seconds; peak inspiratory flow, Qpeak, 0.4 L / sec; expiratory time, Te, 2.4 seconds; peak expiratory flow, Qpeak, -0.5 L / sec. The total duration of the breath, Ttot, is approximately 4 seconds. Humans typically breathe at approximately 15 breaths per minute (BPM), with a ventilation, Vent, of approximately 7.5 L / min. A typical duty cycle, the ratio of Ti to Ttot, is approximately 40%. 5.8 Respiratory Pressure Therapy Mode

[0149] Depending on the values ​​of the parameters A and P0 in the treatment pressure equation (1) used by the treatment parameter determination algorithm 4329 in one form of the present technology, various respiratory pressure treatment modes can be performed by the RPT device 4000.

[0150] In some implementations of this form of the present technology, the amplitude A in the treatment pressure equation (1) is equal to zero, so that the treatment pressure Pt is equal to the base pressure P0 throughout the entire respiratory cycle. Such implementations are primarily grouped under the heading of CPAP treatment. In other implementations of this form of the present technology, the value of the amplitude A in equation (1) is positive. Such implementations are known as bilevel treatment because when the treatment pressure Pt is determined using equation (1) with a positive amplitude A, the treatment parameter determination algorithm 4329 oscillates the treatment pressure Pt between two values ​​or levels in synchronization with the patient's 1000 spontaneous breathing efforts. That is, based on the exemplary waveform template Π(Φ,t) described above, the treatment parameter determination algorithm 4329 increases the treatment pressure Pt to P0+A (known as IPAP) at the beginning or during inspiration and decreases the treatment pressure Pt to the base pressure P0 (known as EPAP) at the beginning or during expiration.

[0151] In some forms of bilevel therapy, the amplitude A is large enough that the RPT device 4000 performs some or all of the breathing work of the patient 1000. Supplementary Help ventilation In this form of ventilation, known as pressure support or pressure controlled ventilation, the amplitude A is referred to as the pressure support or swing. In pressure support ventilation, IPAP is the base pressure P0 plus the pressure support A, and EPAP is the base pressure P0.

[0152] In some forms of pressure support ventilation therapy, known as constant pressure support ventilation therapy, the pressure support A is fixed at a predetermined value (e.g., 10 cmH2O). The predetermined pressure support value is a setting of the RPT device 4000 and may be set, for example, by hard-coded during configuration of the RPT device 4000 or by manual entry via the input device 4220.

[0153] In another form of pressure-support ventilation therapy, commonly known as servo-ventilation, the therapy parameter determination algorithm 4329 takes as input certain currently measured or estimated parameters of the respiratory cycle and a target value for that respiratory parameter, and continuously adjusts the parameters of equation (1) to adjust the currently measured respiratory parameter closer to the target value. T One example of servo ventilation is a fixed time period called the safe volume mode.

[0154] In some forms of servo-ventilation, the therapy parameter determination algorithm 4329 applies a servo-control method that iteratively calculates pressure support A to adjust the current measurement of the respiratory parameter towards a target value. One such servo-control method is proportional-integral (PI) control. In one implementation of PI control for safe volume mode, the adjustment ΔA to the current pressure support A is calculated as follows:

number

[0155] where G is the servo control gain, Cnom is the nominal compliance constant (which is typically set to 60 ml / cmH2O for adults and 40 ml / cmH2O for children, but may be modified for different patient subtypes), and V T (Target) is the target tidal volume (unit: milliliters). Gain G is typically a constant value of 1.

[0156] Other servo-control methods that may be applied by the treatment parameter determination algorithm 4329 include proportional (P), proportional differential (PD), and proportional integral differential (PID).

[0157] The value of pressure support A calculated via equation (2) may be clipped to a range defined as [Amin, Amax]. In this embodiment, pressure support A is calculated based on the tidal volume V T The target tidal volume V T Set as default at minimum pressure support Amin until it falls below (target). Tidal volume V T When the measured value of V falls below the target tidal volume, A begins to increase and V T V again T Only when it exceeds (target) will it drop to Amin.

[0158] The pressure support limits Amin and Amax are settings of the RPT device 4000 and are set, for example, by hard-coded or manual entry through the input device 4220 when the RPT device 4000 is configured. 5.8.1 Handling sudden leakage changes

[0159] A sudden leak change (sudden onset or sudden elimination of a leak) can cause the estimate of the leak flow Ql, and therefore the respiratory flow estimate Qr, to be temporarily inaccurate while the leak flow estimation algorithm 4316 "catches up" to the sudden change. When a leak occurs, the respiratory flow Qr will be overestimated for a period lasting perhaps several breaths. Then, when the leak is eliminated, the respiratory flow Qr will be underestimated for a period of time. In addition, the phase determination algorithm 4321 may over- or under-estimate the respective inspiratory portions of the breath. As a result, when a leak appears, the inspiratory volume Vi will tend to be temporarily overestimated, and the expiratory volume Ve will tend to be temporarily underestimated. When the leak is eliminated, the expiratory volume Ve will tend to be temporarily overestimated, and the inspiratory volume Vi will tend to be temporarily underestimated. In either case, the tidal volume V by the tidal volume estimation algorithm 4323 will be T The estimate of the pressure support A tends to temporarily exceed the actual tidal volume. As a result, in safe volume mode, pressure support A may be inappropriately decreased or increased slower than it should be. FIG. 7A includes a graph 7100 illustrating an example of such behavior. Traces 7110-7130 in graph 7100 represent direct measurements of various respiratory parameters (as opposed to parameters estimated by RPT device 4000 using algorithm 4300). The top trace 7110 shows the therapeutic pressure Pt fluctuating with an amplitude equal to pressure support A. The middle trace 7120 shows the respiratory flow Qr fluctuating between positive (inspiration) and negative (expiration) portions. The bottom trace 7130 shows the integral (i.e., instantaneous volume) of respiratory flow Qr. Therefore, the peak values ​​of the peaks in trace 7130 correspond to the tidal volume V of each successive breath. T Shows.

[0160] At 7140, a leak suddenly occurs. Immediately afterwards, pressure support drops significantly due to an overestimation of tidal volume, before returning to its previous value after a dozen or so breaths. As a result, the delivered tidal volume V TAfter the leak is cleared at 7150 and pressure support drops significantly due to tidal volume being overestimated again, it takes many breaths to return to its previous value, during which the delivered tidal volume V T also decreases significantly.

[0161] In one form of the present technology, the servo control gain G in equation (2) can be dynamically adjusted to reduce this effect of sudden leak changes. As noted above, one effect of the sudden appearance or disappearance of leak is that the estimates of the inspiratory volume Vi and the expiratory volume Ve vary temporarily. Therefore, in one implementation, the servo control gain G is adjusted based on the difference between the estimates of the inspiratory volume Vi and the expiratory volume Ve, such that the difference between the two decreases as the difference between the two increases. In one such implementation, the relative difference tidal volume dv varies between a lower value dvmin and a default value (e.g., 1), so the servo control gain G is adjusted linearly between the default value and a lower value Gmin. Figure 8 shows an example of such an adjustment of the servo control gain G. In the figure, the default value is 1, the lower value Gmin is 0.2, and the lower value dvmin is also 0.2. The relative difference tidal volume dv can be calculated from the most recent breath as follows, with the denominator adjusted to never be zero:

number

[0162] This implementation slows down the rate of adjustment of pressure assist A due to temporary variations in the estimates of inspiratory volume Vi and expiratory volume Ve caused by the sudden appearance or disappearance of a leak. After these estimates converge as the leak flow estimation algorithm 4316 catches up with the sudden leak change, the servo control gain G returns to its normal value of 1. This smooths out the effect of the sudden leak change on the pressure assist servo control, providing more stable therapy when a sudden leak change is encountered.

[0163] Graph 7200 included in Figure 7B illustrates the behavior of the therapy parameter determination algorithm 4329 in one such implementation of the present technology. As in Figure 7A, traces 7210-7230 in graph 7200 illustrate direct measurements of various respiratory parameters (rather than parameters estimated by the RPT device 4000 using algorithm 4300). Top trace 7210 illustrates the therapy pressure Pt, middle trace 7220 illustrates the respiratory flow Qr, and bottom trace 7230 illustrates the integral (i.e., instantaneous amount) of respiratory flow Qr.

[0164] Although a leak suddenly appears at 7240, the drop in pressure support A is much smaller than the drop in trace 7110 at the same stage. As a result, the drop in delivered tidal volume is also smaller than the drop in trace 7130 at the same stage. When the leak is eliminated at 7250 and gain pressure support A drops much smaller than the drop in trace 7110, the drop in delivered tidal volume is also smaller than the drop in trace 7130 at the same stage. Therefore, when a sudden change in leak is encountered, the drop in delivered tidal volume V T The change in is significantly smaller.

[0165] FIG. 9 shows a high-level flowchart of a method 9000 for dynamically adjusting the servo control gain G in the form of an algorithm. The algorithm may be implemented within the therapy engine module 4320 in the respiratory therapy device (RPT4000) or as a separate module. In block 9004, the algorithm is invoked when a sudden leak change is detected. As shown in FIG. 7A, sudden leak detection may be made in response to a change in pressure support or tidal volume. A sudden leak determination may be made based on a rise in the relative difference tidal volume dv (see equation (3)) between an estimate of the inspiratory volume V and an estimate of the exhaled volume V above a certain threshold dvmin for a certain predetermined period of time (e.g., a single breath or multiple breaths). Once a sudden leak is detected, in block 9008, the servo control gain G of the device is adjusted based on the difference between the estimated volume value V and the estimated volume value V. As shown in FIG. 8 and defined in equation (3), this adjustment may vary linearly based on the relative difference in tidal volume dv between the default or normal upper value and the lower minimum value Gmin. In this way, the gain G is dynamically adjusted in response to sudden leaks. This improves the performance of devices using this technology by servo-controlling the degree of support in response to sudden leaks. This reduces the impact of leaks and, therefore, the impact of leaks on operation in safe volume mode, which can be used. Supplementary Help ventilation Such effects can be reflected in changes in

[0166] At decision diamond 9012, the difference between Vi and Ve is examined to determine whether there is convergence (e.g., whether the difference between Vi and Ve is within a certain predetermined range (e.g., the relative difference is 20% or less)). If there is convergence, at block 9016, the gain G is returned to a normal or default value (e.g., 1). If there is no convergence, at block 9008, the gain G can be further adjusted depending on the relative difference between the estimated inhaled volume Vi and the estimated exhaled volume Ve, thereby allowing for an additional level of dynamic adjustment. For example, the gain G can be adjusted linearly based on the calculated relative difference tidal volume dv as shown in FIG. 8 until the convergence criterion is met.

[0167] In another implementation, blocks 9004, 9012, and 9016 are not used, and block 9008 is repeatedly called to adjust the servo control gain G of the system based on the difference between the estimated quantity value Vi and the estimated quantity value Ve.

[0168] By way of example, a respiratory treatment device including a pressure generator, a transducer, and a controller may be configured to operate in accordance with aspects of the present technology. In this example, the pressure generator generates an airflow or gas useful in ventilatory support to a patient. The transducer may then generate a signal indicative of one or more characteristics of the airflow. The controller then processes or analyzes this signal to estimate values ​​of inspiratory and expiratory volumes for one or more patient breaths. The controller is also configured to servo-control the ventilatory support to adjust the estimated tidal volume to approximate a target volume using a gain that is dynamically adjusted based on the difference between the estimated inspiratory and expiratory volumes. This allows for improvements associated with adjusting the estimated tidal volume during sudden leak events. 5.9 Glossary

[0169] For purposes of this disclosure, in certain aspects of the technology, one or more of the following definitions may apply. In other aspects of the technology, other definitions may apply. 5.9.1 General

[0170] Air: In certain forms of the present technology, air may refer to atmospheric air, while in other forms of the present technology, air may refer to a combination of other breathable gases (e.g., oxygen-rich atmospheric air).

[0171] Atmosphere: In certain forms of the present technology, the term "atmosphere" should be taken to mean (i) that which is external to the treatment system or patient, and (ii) that which immediately surrounds the treatment system or patient.

[0172] For example, the atmosphere for a humidifier humidity This may be the humidity of the air immediately surrounding the humidifier (e.g., the humidity inside the room where the patient is sleeping). Such ambient humidity may differ from the humidity outside the room where the patient is sleeping.

[0173] In another example, the ambient pressure may be the pressure immediately surrounding or external to the body.

[0174] In certain embodiments, ambient (e.g., acoustic) noise can be considered the background noise level in the room the patient is in, other than noise emanating from, for example, the RPT device or from the mask or patient interface. Ambient noise can originate from sources outside the room.

[0175] Automatic Positive Airway Pressure (APAP) Therapy: A CPAP therapy that is capable of automatically adjusting therapeutic pressure between minimum and maximum limits, for example, between breaths, depending on the presence or absence of signs of an SDB episode.

[0176] Continuous Positive Airway Pressure (CPAP) Therapy: Respiratory pressure therapy in which the therapeutic pressure is approximately constant throughout the patient's respiratory cycle. In some forms, the pressure at the entrance to the airways increases slightly during exhalation and decreases slightly during inhalation. In some forms, the pressure varies during different respiratory cycles of the patient (e.g., increased in response to the detection of an indication of partial upper airway obstruction and decreased in the absence of notification of partial upper airway obstruction).

[0177] Flow Rate: The instantaneous amount (or mass) of air delivered per unit time. Flow rate can refer to an instantaneous quantity. Sometimes, when referring to flow rate, it refers to a scalar quantity (i.e., a quantity that has only magnitude). In other cases, when referring to flow rate, it refers to a vector quantity (i.e., a quantity that has both magnitude and direction). Flow rate may be given the symbol Q. "Flow rate" may also be called "flow" or "airflow" for shorthand.

[0178] In the example of a patient's breathing, the flow rate may be nominally positive for the inspiratory portion of the patient's breathing cycle, and therefore negative for the expiratory portion of the patient's breathing cycle. Total flow rate Qt is the flow rate of air exiting the RPT device. Vent flow rate Qv is the flow rate of air exiting the vent to allow for the outflow of exhaled gases. Leakage flow rate Ql is the flow rate of leakage from the patient interface system or elsewhere. Respiratory flow rate Qr is the flow rate of air received into the patient's respiratory system.

[0179] Humidifier: The word "humidifier" is construed to mean a humidifying device constructed, arranged, or configured with a physical structure capable of providing a therapeutically beneficial quantity of water (H2O) vapor to an air stream to improve the medical respiratory condition of a patient.

[0180] Leakage: The term "leakage" refers to airflow to or from the environment (except through elements of the air circuit). In one example, leakage may occur due to an imperfect seal between the mask and the patient's face. In another example, leakage may occur at the elbow to the environment. The term "leakage" may also include air exhaled into the tracheostomy tube during invasive ventilation.

[0181] Noise Conduction (Acoustic): In this document, conducted noise refers to noise that is carried to the patient by the pneumatic pathway (e.g., 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.

[0182] Noise Emission (Acoustic): In this document, radiated noise refers to noise carried by the ambient air to the patient. In one form, radiated noise can be quantified by measuring the sound power / pressure level of the target in accordance with ISO 3744.

[0183] Ventilation noise (acoustic): In this document, ventilation noise refers to the noise generated by airflow through any ventilation (eg, ventilation holes in the patient interface).

[0184] Patient: A person with or without a respiratory disease.

[0185] Pressure: Force per unit area. Pressure can be expressed in a variety of units (e.g., cmH2O, gf / cm 2 , and hectopascals). 1cmH2O is 1g-f / cm 2 which is approximately 0.98 hectopascals. In this specification, pressures are given in units of cmH2O unless otherwise specified.

[0186] The pressure in the patient interface is designated by the symbol Pm, and the therapeutic pressure, which represents the target value that the mask pressure Pm should achieve at this time, is designated by the symbol Pt.

[0187] Respiratory Pressure Therapy (RPT): The application to the airway entrance of an air supply at therapeutic pressure, typically positive pressure relative to atmosphere.

[0188] Ventilator: A mechanical device that provides pressure support to a patient while they perform some or all of the work of breathing. 5.9.2 Breathing cycle

[0189] Apnea: According to some definitions, apnea is said to occur when flow below a predetermined threshold continues for a duration of, for example, 10 seconds. Obstructive apnea is said to occur when some airway obstruction does not allow airflow despite patient effort. Central apnea is said to refer to a condition in which apnea is detected due to reduced or absent respiratory effort despite a patent airway. Mixed apnea is said to refer to a condition in which reduced or absent respiratory effort occurs simultaneously with airway obstruction.

[0190] Respiratory rate: The patient's spontaneous breathing rate, usually measured in breaths per minute.

[0191] Duty cycle: The ratio of inspiration time Ti to total breathing time Ttot.

[0192] Exercise (Respiration): Respiratory effort is said to refer to the movement made by the spontaneous breathing of a person trying to breathe.

[0193] Expiratory portion of the respiratory cycle: the period from the start of expiratory flow to the start of inspiratory flow.

[0194] Flow limitation: Flow limitation is understood to be a condition in a patient's breathing where an increase in patient effort does not result in a corresponding increase in flow rate. If flow limitation occurs during the inspiratory portion of the respiratory cycle, the flow limitation can be referred to as inspiratory flow limitation. If flow limitation occurs during the expiratory portion of the respiratory cycle, the flow limitation can be referred to as expiratory flow limitation.

[0195] Hypopnea: By some definitions, hypopnea refers to a reduction in flow, rather than an interruption of flow. In one form, hypopnea is said to occur when flow is reduced below a threshold rate for a sustained period of time. When hypopnea is detected due to a decrease in respiratory effort, central hypopnea is said to occur. In one form, hypopnea may be considered when any of the following occur in adults: (i) A 30% decrease in patient respiration for at least 10 seconds plus an associated 4% desaturation, or (ii) A reduction in patient respiration (less than 50%) lasting at least 10 seconds and associated desaturation of at least 3% or arousal occurs.

[0196] Hyperventilation: An increase in flow to a level higher than normal.

[0197] Inspiratory portion of the respiratory cycle: The period from the start of the inspiratory flow to the start of the expiratory flow is taken as the inspiratory portion of the respiratory cycle.

[0198] Patency (Airway): The degree to which the airway is open or the extent to which it is open. Airway patency is an opening. Airway patency can be quantified, for example, with a value of 1 indicating open and a value of 0 indicating closed (obstructed).

[0199] Positive end-expiratory pressure (PEEP): The pressure above atmosphere in the lungs that exists at the end of expiration.

[0200] Peak flow (Qpeak): The maximum value of flow during the inspiratory portion of the respiratory flow waveform.

[0201] Respiratory airflow, airflow, patient airflow, respiratory airflow (Qr): These terms may be understood to refer to the RPT device's estimate of respiratory flow, and are used in contrast to "true respiratory flow" or "true respiratory flow," which is the patient's actual respiratory flow, usually expressed in liters per minute.

[0202] Tidal volume (V T ): The volume of air inhaled or exhaled during normal breathing without extra effort. 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 V T can be defined as equal to either quantity. In practice, the tidal volume V T is estimated as some combination (e.g., the average of these two quantities).

[0203] (Inspiration) Time (Ti): The duration of the inspiratory portion of the respiratory flow waveform.

[0204] (Expiratory) Time (Te): The duration of the expiratory portion of the respiratory flow waveform.

[0205] (Total) Time (Ttot): The total duration between the start of one inspiratory portion of the respiratory flow waveform and the start of the next inspiratory portion of the respiratory flow waveform.

[0206] Typical Recent Ventilation: The ventilation value around which recent values ​​of ventilationVent over a given time scale tend to cluster (i.e., the degree to which recent values ​​of ventilation tend to be centered).

[0207] Upper Airway Obstruction (UAO): Includes both partial and total upper airway obstruction. May be associated with a state of flow limitation in which flow may increase or decrease slightly with increasing pressure differential across the upper airway (Starling resistor behavior).

[0208] Vent: A measure of the rate of gas exchange performed by a patient's respiratory system. Measurements of ventilation may include either or both inspiratory and expiratory flow per unit time. When expressed as volume per minute, this quantity is often referred to as "minute ventilation." Minute ventilation is sometimes given simply as volume and is understood as volume per minute. 5.9.3 Ventilation

[0209] Adaptive Servo Ventilator (ASV): A servo ventilator that has variable target characteristics rather than fixed target characteristics. The variable target characteristics can be learned from some characteristics of the patient (e.g., the patient's breathing characteristics).

[0210] Backup Rate: A ventilator parameter that establishes the minimum respiratory rate (typically in breaths per minute) that will be delivered to the patient by the ventilator (when not triggered by spontaneous breathing efforts).

[0211] Cycle: The end of the inspiratory phase of a ventilator. When a ventilator delivers breaths to a spontaneously breathing patient, at the end of the inspiratory portion of the breathing cycle, the ventilator is said to be cycled to stop breath delivery.

[0212] Expiratory Positive Airway Pressure (EPAP): The base pressure to which varying pressures are added within a breath to produce the desired mask pressure that the ventilator attempts to achieve at a given moment.

[0213] End Expiratory Pressure (EEP): The desired mask pressure that the ventilator attempts to achieve at the end of the expiratory portion of the breath. If the pressure waveform template Π(Φ) has a value of zero at the end of expiration (i.e., Π(Φ)=0 when Φ=1), then EEP is equal to EPAP.

[0214] Inspiratory Positive Airway Pressure (IPAP): The maximum desired mask pressure that the ventilator attempts to achieve during the inspiratory portion of the breath.

[0215] Pressure Support: A number indicating the increase in pressure during ventilator inspiration compared to the corresponding ventilator expiration, and refers primarily to the pressure difference between the maximum inspiratory pressure and the base pressure (e.g., PS = IPAP - EPAP). In some contexts, pressure support refers to the difference the ventilator attempts to achieve (rather than the difference it actually achieves).

[0216] Servo-ventilator: a ventilator that measures or estimates some parameter of the patient's respiratory cycle and adjusts the level of pressure support to adjust this measured parameter closer to a target parameter value.

[0217] Spontaneous / Timed (S / T): A mode of a ventilator or other device that attempts to detect the onset of a breath in a spontaneously breathing patient. However, if the device fails to detect a breath within a predetermined period of time, the device automatically begins breath delivery.

[0218] Swing: A term equivalent to pressure assistance.

[0219] Triggered: When a ventilator delivers a breath of air to a spontaneously breathing patient, the ventilator is said to be triggered to deliver a breath when the patient himself initiates the breathing portion of the breathing cycle. 5.10 Other Notes

[0220] A portion of the disclosure of this patent document contains material that is entitled to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of this patent document or this patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but reserves all copyright rights therefor for all other purposes.

[0221] Unless otherwise clearly indicated from the context and unless a range of values ​​is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit, between the upper and lower limits of the range, and for any other stated or intervening value in the stated range, is encompassed by the technology. The upper and lower limits of these intervening ranges, independently included in the intervening range, are also encompassed by the technology if they specifically exceed the limits in the stated range. If the stated range includes one or both of these limits, then ranges exceeding either or both of these stated limits are also encompassed by the technology.

[0222] Furthermore, when a value or values ​​are embodied herein as part of the present technology, unless otherwise specified, it is understood that such values ​​may be approximated and may be used to any appropriate significant figures to the extent practical technical practice permits or requires.

[0223] Unless otherwise defined, 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 this technology, a limited number of exemplary methods and materials are described herein.

[0224] Although particular materials are described as being suitable for use in the construction of components, obvious alternative materials having similar properties may be substituted. Furthermore, unless stated to the contrary, any and all components described herein are understood to be manufacturable and therefore may be manufactured collectively or separately.

[0225] Please note that as used herein and in the appended claims, the singular forms "a," "an," and "the" include their plural equivalents unless the context clearly dictates otherwise.

[0226] All publications mentioned herein are incorporated by reference to disclose and describe the methods and / or materials that are the subject of these publications. The publications mentioned herein are provided solely for their disclosure prior to the filing date of this application. Nothing herein should be construed as an admission that the present technology does not antedate such publications by virtue of prior patents. Furthermore, the dates of publications mentioned may differ from the actual publication dates, which may require independent confirmation.

[0227] The terms "comprises" and "comprising" should be construed as referring to elements, components, or steps in a non-exclusive sense, indicating that a described element, component, or step may be present in, utilized with, or combined with other elements, components, or steps not specifically described.

[0228] The headings used in the detailed description are for the convenience of the reader and should not be used to limit the content found in the disclosure or claims as a whole. These headings should not be used in interpreting the scope of the claims or the claim limitations.

[0229] Although the technology herein has been described with reference to specific embodiments, it should be understood that these embodiments are merely illustrative of the principles and applications of the technology. In some cases, terms and symbols may indicate specific details unnecessary for the practice of the technology. For example, although the terms "first" and "second" (etc.) are used, unless otherwise specified, these terms are not intended to indicate any order but are used to distinguish between separate elements. Furthermore, although the process steps in the method may be described or illustrated in an ordered manner, such an order is not required. Those skilled in the art will recognize that such an order can be changed and / or aspects can be performed simultaneously or even synchronously.

[0230] It is therefore to be understood that numerous modifications may be made in the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present technology. 5.11 List of Reference Symbols patient 1000 Patient Interface 3000 Seal forming structure 3100 Plenum Chamber 3200 Structure 3300 Ventilation 3400 Connection port 3600 Forehead support part 3700 RPT Device 4000 Outer Housing 4010 Internal part 4012 Part 4014 Panel 4015 Chassis 4016 Handle 4018 Pneumatic Block 4020 Air Filter 4110 Inlet Air Filter 4112 Outlet Air Filter 4114 Muffler 4120 Inlet muffler 4122 Outlet muffler 4124 Pressure Generator 4140 Blower 4142 Motor 4144 Anti-spillback valve 4160 Air Circuit 4170 Electrical Components 4200 PCBA 4202 power supply 4210 Input Device 4220 Central Controller 4230 Clock 4232 Therapy Device Controller 4240 Protection circuit 4250 Memory 4260 Converter 4270 Pressure Sensor 4272 Flow Sensor 4274 Motor Speed ​​Converter 4276 Data communication interface 4280 Remote External Communications Network 4282 Local external communication network 4284 Remote External Device 4286 Local Foreign Device 4288 Output device 4290 Display driver 4292 Display 4294 Algorithm 4300 Pre-processing module 4310 Pressure compensation algorithm 4312 Airflow rate estimation algorithm 4314 Leakage flow rate estimation algorithm 4316 Respiratory flow estimation algorithm 4318 Treatment Engine Module 4320 Phase Determination Algorithm 4321 Waveform determination algorithm 4322 Tidal volume estimation algorithm 4323 Treatment parameter determination algorithm 4329 Treatment Control Module 4330 Method for detecting fault conditions 4340 Humidifier 5000 Humidifier inlet 5002 Humidifier outlet 5004 Humidifier Base 5006 Humidifier Reservoir 5110 Humidifier Reservoir Dock 5130 heating element 5240 Graph 7100 Trace 7110 Trace 7120 Trace 7130 Graph 7200 Trace 7210 Trace 7220 Trace 7230 Sudden leakage change 7240 Eliminate leaks 7250 method 9000 Block 9004 Block 9008 Judgement Diamond 9012 Block 9016 In order to maintain the disclosure of the present application as originally filed, the contents of claims 1 to 16 as originally filed are added below. (Claim 1) 1. An apparatus for treating disordered breathing in a patient, comprising: a pressure generator configured to generate an airflow to provide ventilatory support to the patient; a transducer configured to generate a signal indicative of a characteristic of the air flow; a controller, analyzing the signal to estimate the patient's inhaled and exhaled respiratory volumes; and servo-controlling the degree of ventilatory support to adjust the estimated tidal volume to approach a target tidal volume, wherein a gain of the servo-control is dependent on a difference between the estimated inhaled volume and the estimated exhaled volume. An apparatus comprising: (Claim 2) The apparatus of claim 1 , wherein the gain decreases with increasing difference between the estimated inspired volume and the estimated expired volume. (Claim 3) 3. The device according to claim 1, wherein the gain depends on the difference between the estimated inhaled volume and the estimated exhaled volume relative to the estimated tidal volume. (Claim 4) 4. The device according to claim 1, wherein the gain depends on the absolute magnitude of the difference between the estimated inhaled volume and the estimated exhaled volume. (Claim 5) 5. The device according to claim 1, wherein the degree of ventilatory support is a pressure support of the ventilatory support. (Claim 6) 1. A method of operating a respiratory treatment device configured to generate an airflow to provide ventilatory assistance to a patient, comprising: measuring a characteristic of the air flow with a transducer; analyzing the measured characteristics in a controller to estimate the patient's inhaled and exhaled respiratory volumes; calculating a gain in a controller based on the difference between the estimated inhaled volume and the estimated exhaled volume; servo-controlling, by a controller, the degree of ventilatory support using the calculated gain to adjust the estimated tidal volume for the patient toward a target tidal volume; The method comprising: (Claim 7) The method of claim 6 , wherein the calculating decreases the gain with increasing difference between the estimated inhaled volume and the estimated exhaled volume. (Claim 8) 8. The method according to claim 6, wherein the gain depends on the difference between the estimated inhaled volume and the estimated exhaled volume relative to the estimated tidal volume. (Claim 9) 9. The method according to claim 6, wherein the gain depends on an absolute magnitude of a difference between the estimated inhaled volume and the estimated exhaled volume. (Claim 10) 10. The method according to claim 6, wherein the degree of ventilatory support is pressure support of the ventilatory support. (Claim 11) 1. A system for treating respiratory disorder in a patient, comprising: means for generating an airflow to provide ventilatory support to a patient; means for generating a signal indicative of a characteristic of said air flow; means for analysing said signals to estimate the patient's inhaled and exhaled respiratory volumes; means for servo-controlling the degree of ventilatory assistance to adjust the estimated tidal volume to approach a target tidal volume; comprising A system wherein the gain of the servo control depends on the difference between the estimated inhaled volume and the estimated exhaled volume. (Claim 12) 1. An apparatus for treating disordered breathing in a patient, comprising: a blower configured to deliver a supply of air to provide ventilatory support to the patient; a transducer configured to generate a signal indicative of a characteristic of the air supply; a controller, analyzing the signal to estimate the patient's inhaled and exhaled respiratory volumes; adjusting a servo control gain based on a difference between the estimated inhaled volume and the estimated exhaled volume; and An apparatus comprising: (Claim 13) 13. The apparatus of claim 12, wherein the controller adjusts the servo control gain such that the gain decreases with increasing difference between the estimated inhaled volume and the estimated exhaled volume. (Claim 14) 14. Apparatus according to any one of claims 12 to 13, wherein adjustment of a servo control gain reduces the rate of adjustment of the pressure assistance of the air supply. (Claim 15) 15. The apparatus of claim 12, wherein the controller is configured to adjust the servo control gain if the difference is greater than or equal to 20%. (Claim 16) 16. The apparatus of claim 12, wherein the controller is further configured to adjust the servo control gain to a default value when the difference returns to a value below 20%.

Claims

1. 1. An apparatus for treating disordered breathing in a patient, comprising: a pressure generator for generating a flow of air to provide assisted ventilation to the patient; a transducer for generating a signal indicative of a characteristic of the air flow; Controller and It is equipped with The controller analyzing the signals to estimate the patient's respiratory inspiratory and expiratory volumes; servo-controlling the magnitude of the assisted ventilation to adjust the estimated tidal volume toward a target tidal volume; a gain of the servo control is dependent on a difference between an estimated inspiratory volume and an estimated expiratory volume relative to the estimated tidal volume, and a magnitude of the assisted ventilation is a pressure increment, the pressure increment being a pressure difference between a maximum pressure at inspiration and a base pressure at expiration; Device.

2. The apparatus of claim 1 , wherein the gain decreases with increasing difference between the estimated inspired volume and the estimated expired volume.

3. 3. The device of claim 1, wherein the gain depends on the absolute magnitude of the difference between the estimated inspired volume and the estimated expired volume.

4. 1. A method of operating a respiratory treatment device that generates an airflow to provide assisted ventilation to a patient, comprising: a transducer of the respiratory treatment device measuring a characteristic of the generated airflow; a controller of the respiratory treatment device analyzing the measured characteristics to estimate the patient's respiratory inspiratory and expiratory volumes; a controller of the respiratory treatment device calculating a servo control gain based on a difference between the estimated inhaled volume and the estimated exhaled volume relative to an estimated tidal volume; a controller of the respiratory therapy device servo-controlling the magnitude of the auxiliary ventilation using the calculated servo control gain to adjust the estimated tidal volume for the patient toward a target tidal volume, the magnitude of the auxiliary ventilation being a pressure increment, the pressure increment being the pressure difference between a peak pressure on inspiration and a base pressure on expiration; The method comprising:

5. The method of claim 4 , wherein the calculating decreases the servo control gain with increasing difference between the estimated inhaled volume and the estimated exhaled volume.

6. The method of claim 4 or 5, wherein the gain depends on the absolute magnitude of the difference between the estimated inspired volume and the estimated expired volume.

7. 7. The method according to claim 4, wherein the servo control gain is dependent on a relative difference tidal volume, the relative difference tidal volume being obtained by dividing the determined difference by the estimated tidal volume.

8. 1. A system for treating respiratory disorder in a patient, comprising: a pressure generator that generates a flow of air to provide assisted ventilation to the patient; a transducer for generating a signal indicative of a characteristic of the air flow; a controller that analyzes the signals to estimate the inspiratory and expiratory volumes of the patient's breath and servo-controls the magnitude of the assisted ventilation to adjust the estimated tidal volume toward a target tidal volume, the magnitude of the assisted ventilation being a pressure increment, the pressure increment being the pressure difference between a peak pressure at inspiration and a base pressure at expiration; It is equipped with A system wherein the gain of the servo control depends on the difference between the estimated inhaled volume and the estimated exhaled volume relative to the estimated tidal volume.

9. 1. An apparatus for treating disordered breathing in a patient, comprising: a blower for delivering a supply of air to provide assisted ventilation to the patient; a transducer for generating a signal indicative of a characteristic of the air supply; Controller and It is equipped with The controller analyzing the signals to estimate the patient's respiratory inspiratory and expiratory volumes; adjusting a servo control gain for a pressure increment of the assisted ventilation based on a difference between the estimated inspiratory volume and the estimated expiratory volume relative to an estimated tidal volume, the pressure increment being the pressure difference between a maximum pressure during inspiration and a base pressure during expiration; Device.

10. 10. The apparatus of claim 9, wherein the controller adjusts the servo control gain such that the gain decreases with increasing difference between the estimated inhaled volume and the estimated exhaled volume.

11. An apparatus as described in claim 9 or 10, wherein adjusting the servo control gain reduces the adjustment speed of the pressure assistance of the air supply.

12. Apparatus according to any one of claims 9 to 11, wherein the controller is configured to adjust the servo control gain if the difference is greater than or equal to 20%.

13. An apparatus according to any one of claims 9 to 12, wherein the controller is further configured to adjust the servo control gain to a default value when the difference falls back below 20%.

14. 14. The apparatus of claim 9, wherein the servo control gain is dependent on a relative difference tidal volume, the relative difference tidal volume being obtained by dividing the determined difference by the estimated tidal volume.

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