Methods and apparatus for respiratory therapy

Abstract

Methods and apparatuses, such as a controller of a respiratory treatment device, generate a signal representing an estimate of flow of air from the device. The respiratory treatment device can include a motor-operated blower. The method can include receiving, in the controller, signals generated by a set of sensors including measurements of pressure and frequency (e.g., speed) of the motor. The controller can be configured to calculate an entrained air density function and generate the estimate signal based on a function of the measurements of pressure and frequency and the entrained air density function. The entrained air density function can apply signals from additional sensors, such as atmospheric pressure, gas temperature, and ambient relative humidity, to calculate air density. Control operations of the treatment device can then be based on the estimated signal, which can be used to estimate accuracy of signals from flow sensors.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims the benefit of U.S. Provisional Application No. 62 / 880,533, filed July 30, 2019, the disclosure of which is incorporated by reference herein in its entirety. BACKGROUND 2.1 TECHNICAL FIELD

[0004] The present technology relates to one or more of screening, diagnosis, monitoring, treatment, prevention and amelioration of respiratory-related disorders. The present technology also relates to medical devices or apparatuses, and their use, such as methods and devices for estimating flow, such as for assessing accuracy of a flow sensor, detecting a system or respiratory condition, and / or controlling operation. Such processes can be implemented without a flow sensor or a flow sensor operating properly.

[0005] 2.2 DESCRIPTION OF RELATED ART

[0006] 2.2.1 The Human Respiratory System and Its Disorders

[0007] The respiratory system of the body facilitates gas exchange. The nose and mouth form the entrance to the airways of a patient.

[0008] The airways include a sequence of branching tubes when the branching airways penetrate deeper into the lung they become narrower, shorter and more numerous. The main function of the lung is gas exchange, allowing oxygen to flow from air into venous blood and carbon dioxide to flow from blood into air. The trachea divides into the left and right main bronchus, which eventually subdivide into terminal bronchioles. The bronchi constitute the conducting airways and do not participate in gas exchange. Further airway branching leads to the respiratory bronchioles and eventually to the alveoli. The alveolar region of the lung is where gas exchange occurs and is known as the respiratory zone. See West, John B. Respiratory Physiology, 9thedition, Lippincott Williams & Wilkins, 2011.

[0009] There is a range of disorders of the respiratory system. Certain disorders can be characterised by particular events, such as apnoea, hypopnoea, and hyperpnoea.

[0010] Obstructive sleep apnea (OSA) is a form of sleep-disordered breathing (SDB) characterized by events involving closure or obstruction of the upper airway during sleep. It arises from a combination of abnormally small upper airway size and normal loss of muscle tone in the areas of the tongue, soft palate, and posterior oropharyngeal walls during sleep. The condition causes affected individuals to stop breathing, typically for periods ranging from 30 to 120 seconds, sometimes 200 to 300 times per night. It frequently leads to excessive daytime sleepiness and can potentially cause cardiovascular disease and brain damage. Concomitant symptoms are common, especially in middle-aged overweight men, but those affected may not be aware of the problem. See U.S. Patent No. 4,944,310 (Sullivan).

[0011] Cheyne-Stokes respiration (CSR) is another form of sleep-disordered breathing. CSR is a disorder of the patient's respiratory controller, characterized by rhythmic alternating cycles of waxing and the desire to breathe, known as CSR cycles. CSR is characterized by repeated deoxygenation and reoxygenation of arterial blood. Due to repeated hypoxia, CSR can be harmful. In some patients, CSR is associated with repetitive awakenings from sleep, leading to severe sleep disruption, increased sympathetic activity, and increased afterload. See U.S. Patent No. 6,532,959 (Berthon-Jones).

[0012] Respiratory failure is a general term for respiratory disorders in which a patient is unable to adequately ventilate to balance the CO2 in their blood if their metabolic activity is elevated to a level far above resting level. Respiratory failure includes all of the following conditions.

[0013] Obesity hyperventilation syndrome (OHS) is defined as a combination of severe obesity and waking chronic hypercapnia in the absence of other known causes of hypoventilation. Symptoms include dyspnea, morning headache, and excessive daytime sleepiness.

[0014] Chronic obstructive pulmonary disease (COPD) includes any of a group of lower airway diseases that share certain common characteristics. These include increased resistance to air movement, prolonged expiratory phase of breathing, and loss of normal lung elasticity. Examples of COPD include emphysema and chronic bronchitis. COPD is caused by chronic smoking (a major risk factor), occupational exposure, air pollution, and genetic factors. Symptoms include shortness of breath on exertion, chronic cough, and excessive sputum production.

[0015] Neuromuscular disease (NMD) is a broad term encompassing many conditions and ailments that impair muscle function directly through intrinsic muscle pathology or indirectly through neuropathology. Some NMD patients are characterized by progressive muscle damage that leads to loss of mobility, wheelchair use, dysphagia, respiratory muscle weakness, and ultimately death from respiratory failure. Neuromuscular disorders can be classified as rapidly progressive or slowly progressive: (i) rapidly progressive disorders: characterized by muscle damage that worsens within months and leads to death within years (e.g., juvenile amyotrophic lateral sclerosis (ALS) and Duchenne muscular dystrophy (DMD); (ii) variable or slowly progressive disorders: characterized by muscle damage that worsens over many years and only slightly reduces life expectancy (e.g., limb girdle, scapular humerus, and myotonic dystrophy). Symptoms of respiratory failure in NMD include increased general weakness, dysphagia, difficulty breathing at exertion and rest, fatigue, somnolence, morning headache, and difficulty with attention and mood changes.

[0016] Chest wall disorders are a group of chest deformities that result in inefficient coupling between the respiratory muscles and the pleural cavity. These disorders are typically characterized by restrictive defects and have the potential to lead to chronic hypercapnia-related respiratory failure. Scoliosis and / or kyphosis can cause severe respiratory failure. Symptoms of respiratory failure include: forced dyspnea, peripheral edema, orthopnea, recurrent chest infections, morning headache, fatigue, poor sleep quality, and loss of appetite.

[0017] A range of treatments have been used to treat or improve such symptoms. Furthermore, these treatments can be used by other healthy individuals to prevent respiratory distress. However, these treatments have many drawbacks.

[0018] 2.2.2 Treatment

[0019] Continuous positive airway pressure (CPAP) has been used to treat obstructive sleep apnea (OSA). Its mechanism of action is that CPAP acts as an air splint and prevents upper airway obstruction, such as by pushing the soft palate and tongue forward and away from the posterior oropharyngeal wall. Treatment for OSA with CPAP can be voluntary, so patients can choose not to adhere to the therapy if they find the device used to provide one or more of the following: uncomfortable, difficult to use, expensive, or unsightly.

[0020] Noninvasive ventilation (NIV) provides ventilatory support to patients through the upper airway to help them breathe and / or maintain adequate oxygen levels by performing some or all of their breathing efforts. This ventilatory support is delivered via a non-invasive patient interface. NIV has been used to treat chronic respiratory failure (CSR) and respiratory failure in forms such as orthostatic hypoxia (OHS), chronic respiratory disease (COPD), non-invasive disease (NMD), and chest wall disorders. In some forms, it can improve the comfort and effectiveness of these treatments.

[0021] Patients receiving noninvasive ventilation, especially when asleep and / or sedated, often suffer from upper airway instability and collapse, as in OSA. This instability and collapse can impair the effectiveness of ventilation therapy by reducing or even eliminating the pressure actually reaching the lungs from the ventilator.

[0022] The upper airway can be stabilized by maintaining a positive basal pressure (referred to here as EPAP), on which ventilatory assistance is superimposed. Insufficient EPAP allows upper airway collapse, while excessive EPAP can completely stabilize the upper airway but negatively impact comfort, promote mask leakage, or cause cardiovascular complications. The task of selecting an EPAP sufficient to generally maintain upper airway stability across sleep states, postures, sedation levels, and disease progression while avoiding negative side effects (referred to as the task of EPAP titration) is a significant challenge, even for experienced clinicians who have benefited from complete polysomnography (PSG) studies. Appropriately titrated EPAP is a balance between extremes, not necessarily a balance to prevent all obstructive events. While the use of noninvasive ventilation (NIV) is increasing globally, only a subset of patients are given NIV, which has benefited PSG studies to titrate EPAP. In more acute settings, historically, there has been limited understanding of the effects of sleep and sedation on the efficacy of noninvasive ventilation.

[0023] Therefore, there is a great need for NIV therapies that can dynamically respond to changes in the upper airway of NIV patients and automatically adjust EPAP (i.e., perform “EPAP auto-titering”).

[0024] 2.2.3 Treatment System

[0025] These treatments can be provided by treatment systems or devices. Such systems and devices can also be used to diagnose conditions without treating them.

[0026] The treatment system may include a respiratory therapy device (RPT device), an air circuit, a humidifier, a patient interface, and data management.

[0027] 2.2.3.1 Patient Interface

[0028] The patient interface can be used, for example, to connect a breathing device to its wearer by providing an airflow to an inlet in the airway. The airflow can be provided to the patient's nose and / or mouth via a mask, to the mouth via a tube, or to the patient's trachea via a tracheostomy tube. Depending on the treatment to be applied, the patient interface can form a seal with an area such as the patient's face, thereby facilitating the delivery of gas at a pressure sufficiently different from ambient pressure (e.g., a positive pressure of approximately 10 cmH2O relative to ambient pressure) to achieve the treatment. For other forms of treatment, such as oxygen delivery, the patient interface may not include a seal sufficient to facilitate the delivery of a gas supply at a positive pressure of approximately 10 cmH2O to the airway.

[0029] 2.2.3.2 Respiratory Therapy (RPT) Device

[0030] Air pressure generators are known in applications such as industrial-scale ventilation systems. However, air pressure generators for medical applications have specific requirements that are not met by more general air pressure generators, such as the reliability, size, and weight requirements of medical devices. Furthermore, even devices designed for medical use may have disadvantages regarding one or more of the following: comfort, noise, ease of use, efficiency, size, weight, manufacturability, cost, and reliability.

[0031] One known RPT device for treating sleep-disordered breathing is the S9 Sleep Therapy System manufactured by ResMed Limited. Another example of an RPT device is a ventilator. Ventilators such as the ResMed Stellar... TM The range of adult and pediatric ventilators can support a range of patients with invasive and non-invasive non-dependent ventilation for the treatment of a variety of conditions, such as, but not limited to, NMD, OHS and COPD.

[0032] ResMed Elisée TM 150 ventilators and ResMed VS III TM Ventilators provide support for invasive and non-invasive dependent ventilation in adult or pediatric patients for the treatment of a variety of disorders. These ventilators offer volumetric and pressure-based ventilation modes with single- or dual-branch circuits. RPT (Respiratory Pressure Test) devices typically include a pressure generator, such as a motor-driven or motor-operated blower or compressed gas reservoir, and are configured to supply airflow to the patient's airway. In some cases, the airflow can be supplied to the patient's airway at positive pressure, such as using a pressure control loop based on a pressure setpoint controller or a flow control loop based on a flow setpoint controller. The outlet of the RPT device is connected via an air circuit to a patient interface such as those described above.

[0033] RPT devices can include, for example, high-flow-rate therapy devices configured to provide high-flow-rate therapy. In this respect, some respiratory therapies may be designed to deliver a prescribed respiratory volume by delivering an inspiratory flow distribution (which may be superimposed on a positive baseline pressure) over a target duration. In other cases, the interface to the patient's airway is 'open' (unsealed), and the respiratory therapy may supplement only the patient's own spontaneous breathing with a regulated or enriched flow of gas. In one example, high-flow-rate therapy (HFT) delivers a continuous, heated, humidified flow of air to the airway inlet through an unsealed or open patient interface at a 'therapeutic flow rate' that remains substantially constant throughout the respiratory cycle. This therapeutic flow rate is nominally set to exceed the patient's peak inspiratory flow rate. HFT has been used to treat OSA, CSR, respiratory disorders, COPD, and other respiratory diseases. One mechanism of action is that the high flow rate of air at the airway inlet improves ventilation efficiency by flushing or removing exhaled CO2 from the patient's anatomical dead space. Therefore, HFT is sometimes referred to as dead space therapy (DST). Other benefits may include warming and humidification (which can be beneficial for secretion management) and the possibility of a moderate increase in airway pressure. As an alternative to constant flow, therapeutic flow can follow a curve that varies with the respiratory cycle.

[0034] 2.2.3.3 Humidifier

[0035] Delivering airflow without humidification can lead to airway dryness. Humidifiers using an RPT device and patient interface generate humidified gas, minimizing dryness of the nasal mucosa and increasing patient airway comfort. Furthermore, in colder climates, warm air applied to the patient interface and the facial area around the patient interface is generally more comfortable than cold air. A range of artificial humidification devices and systems are known; however, they may not meet the specific requirements of medical humidifiers.

[0036] 2.2.4 Monitoring System

[0037] Screening and diagnosis generally describe the identification of a disorder from its signs and symptoms. Screening typically provides a true / false result, indicating whether the patient's disorder is severe enough to warrant further investigation, while diagnosis provides clinically actionable information. Screening and diagnosis tend to be one-off processes, while monitoring disorder progression can continue indefinitely. Some screening / diagnostic systems are only for screening / diagnosis, while others can also be used for monitoring.

[0038] Polysomnography (PSG) is a routine system for diagnosing / monitoring cardiopulmonary disorders and typically involves clinical expertise in its application. PSG usually involves placing 15 to 20 contact sensors on the body to record various biosignals, such as electroencephalograms (EEG), electrocardiograms (ECG), electrooculograms (EOG), and electromyograms (EMG). PSG for sleep-disordered breathing involves two nights of clinical observation: one night for pure diagnosis and the second night for titration of treatment parameters by a clinician. Clinicians can appropriately diagnose or monitor patients based on visual observation of PSG signals. However, there are situations where clinical expertise may be unavailable or unaffordable. Therefore, PSG is expensive and inconvenient. In particular, it is not suitable for home diagnosis / monitoring.

[0039] More convenient home screening / diagnostic / monitoring systems include a nasal cannula, a pressure sensor, a processing unit, and a recording component. The nasal cannula is a device comprising a protrusion with two hollow end openings configured to be non-invasively inserted a short distance into a patient's nostril to minimize interference with breathing. The hollow protrusions are in fluid communication with a pressure transducer via a Y-tube. The pressure transducer provides a data signal representing the pressure at the patient's nostril inlet (nasal pressure). It has been shown that the nasal pressure signal is a satisfactory alternative to the nasal flow signal generated by a flow transducer connected in series with a sealed nasal mask, as the nasal pressure signal is comparable in shape to the nasal flow signal. The processing unit can be configured to analyze the nasal pressure signal from the pressure transducer in real-time or near real-time to detect and classify SDB events for monitoring the patient's condition. Screening or diagnosis may require similar analysis, but not necessarily in real-time or near real-time. Therefore, the recording unit is configured to record the nasal pressure signal from the pressure transducer for later offline or "batch" analysis by the processing device for screening / diagnostic purposes.

[0040] Additionally, in monitoring respiratory status during respiratory therapy, such as in determining changes in whether controlled treatment should be provided and / or detecting conditions, measurements of the patient's respiratory flow can be helpful. These measurements can be derived from the total flow signal provided by the flow sensor of the RPT generator. For example, measurements of the patient's respiratory flow can be used to detect when the patient transitions from inspiration to expiration, or from expiration to inspiration, to determine when to deliver an expiratory or inspiratory treatment setting. Similarly, measured patient respiratory flow signals can be used to detect patient flow restriction, apnea, hypopnea, and / or other respiratory-related or sleep-disorder-related conditions / events. These detected events provide an assessment of the patient's condition and can be applied to automated control systems, such as for treatment adjustments, such as changing pressure control parameters (e.g., pressure setpoint) or flow control parameters (e.g., flow setpoint) involved in the control of the respiratory therapy device. Examples of such adjustments are illustrated in U.S. Patents 5,704,345 and 10,350,379. For these purposes, the measured flow signal can be obtained from a flow sensor such as a differential pressure transducer or anemometer.

[0041] It may be desirable to further develop methods and apparatus for estimating flow signals to improve existing methods and apparatus and / or develop new therapeutic and detection methods and apparatus. For example, to ensure the accurate performance of respiratory equipment, it may be desirable to develop methods for monitoring or detecting the accuracy of sensors (such as flow sensors) before and / or during use, for detecting malfunctions of such sensors, and / or for detecting system or respiratory conditions, such as in the absence of a flow sensor or in the absence of a properly functioning flow sensor. Summary of the Invention

[0042] This technology aims to provide medical devices that can be used to screen, diagnose, monitor and / or treat respiratory disorders, having one or more of the following: improved comfort, cost, efficacy, ease of use and manufacturability.

[0043] Some forms of this technology may include determining an estimate of the flow rate of the breathable gas associated with the airflow generator.

[0044] Some forms of this technology may include a method of controller for generating a signal representing an estimate of the flow rate of a breathable airflow associated with a respiratory therapy device. The respiratory therapy device may include a motor-operated blower. The method may include receiving, in the controller, an electronic signal representing a pressure measurement of the breathable gas from a pressure sensor. The method may include receiving, in the controller, an electronic signal representing a motor speed measurement from a speed sensor. The method may include calculating an entrained air density function in the controller. The method may include generating, in the controller, a signal representing an estimate of the flow rate of the breathable gas having a flow estimation function. The flow estimation function may include (a) a signal representing a pressure measurement, (b) a signal representing a motor speed measurement, and (c) a function representing an entrained air density function.

[0045] In some forms, the entrained air density function may include an air density value and an air density reference value. The entrained air density function may include a first ratio of the air density value to the air density reference value. The entrained air density function may include a second ratio of the air density value to the air density reference value. The method may include determining an estimate of the breathable gas flow rate, and may also include calculating a motor power, wherein the determined estimate of the breathable gas flow rate may be based on the motor power. The entrained air density function may include a function of atmospheric pressure, temperature, and relative humidity values.

[0046] In some forms, the method may further include evaluating a signal from an oxygen sensor to calculate an entrained air density function. The method may include receiving, in a controller, an electronic signal representing a measurement of atmospheric pressure of the breathable gas from an atmospheric pressure sensor, wherein the atmospheric pressure value may be a measurement of the atmospheric pressure of the breathable gas. The method may include receiving, in a controller, an electronic signal representing a measurement of the gas temperature of the breathable gas from a gas temperature sensor, wherein the gas temperature value may be a measurement of the gas temperature of the breathable gas. The method may also include receiving, in a controller, an electronic signal representing a measurement of the ambient relative humidity of the breathable gas from an ambient relative humidity sensor, wherein the ambient relative humidity value may be a measurement of the ambient relative humidity of the breathable gas.

[0047] In some forms, the function of atmospheric pressure, temperature, and relative humidity can include a saturated vapor pressure function based on temperature. The saturated vapor pressure function based on temperature can be defined as:

[0048]

[0049] Temp local_DegCThis can be a temperature value. Functions of atmospheric pressure, temperature, and relative humidity can include vapor pressure functions based on temperature and relative humidity. A vapor pressure function based on temperature and relative humidity can be defined by multiplying the result of (a) the saturated vapor pressure function based on temperature by (b) the relative humidity value, as follows:

[0050] RH local *Psv(Temp local_DegC )

[0051] RH local It can be a relative humidity value, where Psv(Temp) local_DegC It can be a function of saturated vapor pressure based on temperature.

[0052] In some forms, a function of atmospheric pressure, temperature, and relative humidity can be defined as:

[0053]

[0054] Among them, P0=103hectoPascals; T0=15degrees Celsius or 288.15degrees Kelvin; P atm_local It can be an atmospheric pressure value; it can be a vapor pressure function based on temperature and relative humidity; and Temp local_DegK It can be a temperature value.

[0055] In some forms, the flow estimation function may include a set of frequency functions. This set of frequency functions may include a first rotational frequency function, which is a function of the motor speed measurement and the entrained air density function. This set of frequency functions may include a second rotational frequency function, which is a function of the motor speed measurement. This set of frequency functions may include a third rotational frequency function, which is a function of the motor speed measurement and the entrained air density function. The first rotational frequency function may be defined as:

[0056]

[0057] RPM can be a measurement of motor speed; It can be an entrained air density function; and C1 and C2 are constants derived empirically. The second rotational frequency function can be defined as:

[0058] -C3*RPM 2 -C4*RPM-C5

[0059] Where RPM can be a measured value of the motor speed; and C3, C4, and C5 are constants derived empirically. In some forms, the third rotational frequency function can be defined as:

[0060]

[0061] RPM can be a measurement of motor speed; It can be an entrained air density function; and C6, C7, and C8 are constants derived empirically. The flow estimation function can be defined as:

[0062]

[0063] Where A can be a first rotational frequency function; B can be a second rotational frequency function; C can be a third rotational frequency function; and Pres_meas can be a measurement of the breathable gas pressure from a pressure sensor.

[0064] In some forms, the method may include receiving an electronic signal representing a measurement of the flow rate of a breathable gas from a flow sensor in a controller. The method may include comparing the electronic signal representing the breathable gas flow rate measurement with a generated signal representing an estimated breathable gas flow rate in the controller. The method may include generating an output indicator by the controller representing an accuracy estimate based on the compared flow sensor signal. The method may include modifying control parameters for operating a motor-operated blower by the controller based on the output indicator. The method may include modifying control parameters for operating a motor-operated blower by the controller based on the generated signal representing an estimated flow rate of the breathable gas. The control parameters may be either a pressure setpoint or a flow rate setpoint.

[0065] Some forms of this technology may include a processor-readable medium having processor-executable instructions stored thereon, which, when executed by a processor of a controller for a motor-operated blower in a respiratory therapy device, cause the processor to generate an estimate of the flow rate of breathable gas associated with the respiratory therapy device. The processor-executable instructions may include instructions for controlling the operation of any method described herein.

[0066] Some forms of this technology may include a respiratory therapy device. The respiratory therapy device may include an electric blower adapted to couple with a patient breathing interface and adapted to generate respiratory therapy, which may include a breathable airflow via the patient breathing interface. The respiratory therapy device may include a pressure sensor configured to generate an electronic signal representing a pressure measurement of the breathable gas. The respiratory therapy device may include a speed sensor configured to generate an electronic signal representing a measurement of the speed of the motor. The respiratory therapy device may include a controller that may include one or more processors and is coupled to the blower operated by the motor, the pressure sensor, and the speed sensor. The controller may be configured to receive the electronic signal representing a pressure measurement of the breathable gas. The controller may be configured to receive an electronic signal representing a speed measurement of the motor. The controller may be configured to calculate an entrained air density function. The controller may be configured to use a flow estimation function to generate a signal representing an estimate of the flow rate of the breathable gas, the flow estimation function may include (1) a signal representing a pressure measurement, (b) a signal representing a motor speed measurement, and (c) a function representing an entrained air density function.

[0067] In some forms, the entrained air density function may include an air density value and an air density reference value. The entrained air density function may include a first ratio of the air density value to the air density reference value. The entrained air density function may include a second ratio of the air density value to the air density reference value. 31. In some forms of respiratory therapy devices, to determine an estimate of the flow rate of the breathable gas, the controller may also be configured to calculate a motor power based on one or more sensor signals, wherein the determined estimate of the flow rate of the breathable gas may be based on the motor power. The entrained air density function may include a function of atmospheric pressure values, temperature values, and relative humidity values. The controller may also be configured to evaluate signals from an oxygen sensor for calculating the entrained air density function.

[0068] In some forms, the respiratory therapy device may include an atmospheric pressure sensor configured to generate an electronic signal representing a measurement of the atmospheric pressure of the breathable gas, wherein the atmospheric pressure value may be a measurement of the atmospheric pressure of the breathable gas. The respiratory therapy device may include a gas temperature sensor configured to generate an electronic signal representing a measurement of the gas temperature of the breathable gas, wherein the gas temperature value may be a measurement of the gas temperature of the breathable gas. The respiratory therapy device may include an ambient relative humidity sensor representing a measurement of the ambient relative humidity of the breathable gas, wherein the ambient relative humidity value may be a measurement of the ambient relative humidity of the breathable gas. A controller may be configured to receive an electronic signal representing a measurement of atmospheric pressure. A controller may be configured to receive an electronic signal representing a gas temperature measurement. A controller may be configured to receive an electronic signal representing a measurement of ambient relative humidity.

[0069] In some forms, the function of atmospheric pressure, temperature, and relative humidity can include a function of saturated vapor pressure based on temperature. A function of saturated vapor pressure based on temperature can be defined as described herein. The function of atmospheric pressure, temperature, and relative humidity can include a vapor pressure function based on temperature and relative humidity. A vapor pressure function based on temperature and relative humidity can be defined by multiplying (a) the result of (b) a saturated vapor pressure function based on temperature by (b) a relative humidity value as described herein. The function of atmospheric pressure, temperature, and relative humidity can be defined as described herein.

[0070] In some forms, the flow estimation function of a respiratory therapy device may include a set of frequency functions. This set of frequency functions may include a first rotational frequency function, which is a function of the motor speed measurement and the entrained air density function. This set of frequency functions may include a second rotational frequency function, which is a function of the motor speed measurement. This set of frequency functions may include a third rotational frequency function, which is a function of the motor speed measurement and the entrained air density function. The first rotational frequency function may be defined as described herein. The second rotational frequency function may be defined as described herein. The third rotational frequency function may be defined as described herein. The flow estimation function may be defined as:

[0071]

[0072] Where A can be a first rotational frequency function; B can be a second rotational frequency function; C can be a third rotational frequency function; and Pres_meas can be a measurement of the breathable gas pressure from a pressure sensor.

[0073] In some forms, the respiratory therapy device may also include a flow sensor configured to generate an electronic signal representing a measurement of the flow rate of the breathable gas. The controller may also be configured to receive the electronic signal representing the measurement of the breathable gas flow rate. The controller may also be configured to compare the electronic signal representing the measurement of the breathable gas flow rate with a generated signal representing an estimate of the breathable gas flow rate. The controller may also be configured to generate an output indicator based on the comparison, representing an estimate of the accuracy of the flow sensor. The controller may also be configured to modify control parameters for operating a motor-operated blower based on the output indicator. The controller may also be configured to modify control parameters for operating a motor-operated blower based on the generated signal representing the estimate of the breathable gas flow rate. The control parameters may be either a pressure setpoint or a flow setpoint.

[0074] Some forms of this technology may include a respiratory therapy device as described herein, and may also include a processor-readable medium storing processor-executable instructions that, when executed by one or more processors of a controller of a blower operated by the motor, cause the one or more processors to generate an estimate of the flow rate of the breathable gas, wherein the processor-executable instructions include instructions for controlling operation according to any of the methods described herein.

[0075] The methods, systems, apparatuses, and devices described herein can provide improved functionality in processors of controllers such as dedicated computer processors, respiratory monitors, and / or controllers of respiratory therapy devices. Furthermore, the described methods, systems, apparatuses, and devices can provide improvements in the field of automated management, monitoring, and / or treatment of respiratory conditions, including, for example, sleep-disordered breathing. In this regard, the technical methods described herein can help address problems associated with improving reliability in the automated determination of respiratory flow and / or gas flow rate in respiratory devices.

[0076] Of course, some of these aspects can form sub-aspects of this technology. Moreover, sub-aspects and / or aspects of the aspects can be combined in various ways and also constitute other aspects or sub-aspects of this technology.

[0077] Other features of the present technology will become apparent from the following detailed description, abstract, drawings and claims. Attached Figure Description

[0078] This technology is illustrated by way of example and not limitation in the figures, and similar reference numerals in the figures refer to similar elements, including:

[0079] 4.1 Treatment System

[0080] Figure 1 A system is shown in which a patient 1000 wearing a patient interface 3000 in a full-face mask receives a positive-pressure air supply from an RPT device 4000. The air from the RPT device is humidified in a humidifier 5000 and delivered to the patient 1000 along an air circuit 4170.

[0081] 4.2 Respiratory System and Facial Anatomy

[0082] Figure 2 This diagram illustrates an overview of the human respiratory system, which includes the nasal cavity and oral cavity, larynx, vocal cords, esophagus, trachea, bronchi, lungs, alveolar sacs, heart, and diaphragm.

[0083] 4.3 Patient Interface

[0084] Figure 3 A patient interface in the form of a nasal mask according to the present technology is shown.

[0085] 4.4RPT device

[0086] Figure 4A An RPT device of one form according to the present technology is shown.

[0087] Figure 4B This is a schematic diagram of the pneumatic path of one form of RPT device according to this technology. The upstream and downstream directions are indicated.

[0088] Figure 4C This is a schematic diagram of the electrical components of one form of RPT device according to the present technology.

[0089] Figure 4D This is a schematic diagram of an algorithm implemented in an RPT device according to one form of this technology.

[0090] 4.5 Humidifier

[0091] Figure 5A This is an isometric view of one form of humidifier according to this technology.

[0092] Figure 5B An isometric view of one form of humidifier according to the present technology is shown, illustrating the humidifier reservoir 5110 removed from the humidifier reservoir base 5130.

[0093] 4.6 Respiratory waveform

[0094] Figure 6AThe diagram shows a typical model respiratory flow waveform for a person during sleep. The horizontal axis represents time, and the vertical axis represents respiratory flow. Although parameter values ​​can vary, typical breathing can be approximated by the following: tidal volume (Vt) 0.5 L, inspiratory time (Ti) 1.6 s, peak inspiratory flow (Qpeak) 0.4 L / s, expiratory time (Te) 2.4 s, and peak expiratory flow (Qpeak) -0.5 L / s. The total duration of breathing, Ttot, is approximately 4 s. A person typically breathes at a rate of approximately 15 breaths per minute (BPM), with an outlet ventilation of approximately 7.5 L / min. The typical duty cycle is a ratio of Ti to Ttot of approximately 40%.

[0095] Figure 6B The diagram shows a scaled inspiratory portion of the respiratory flow waveform, illustrating an example of a patient experiencing “classic flatness” inspiratory flow restriction.

[0096] Figure 6C The diagram shows a scaled inspiratory portion of the respiratory flow waveform, with an example of a patient experiencing “chair-shaped” (post-flattening) inspiratory flow restriction.

[0097] Figure 6D The diagram shows a scaled inspiratory portion of the respiratory flow waveform, with an example of a patient experiencing “reverse chair” (early flattening) inspiratory flow restriction.

[0098] Figure 6E The diagram shows a scaled inspiratory portion of the respiratory flow waveform, with an example of a patient experiencing “M-shaped” inspiratory flow restriction.

[0099] Figure 6F The diagram shows a scaled inspiratory portion of the respiratory flow waveform, illustrating an example of a patient experiencing severe “M-shaped” inspiratory flow restriction.

[0100] 4.7 Flow Signal Estimation

[0101] Figure 7 This is an example diagram illustrating a method / system for generating signals that can be used, such as those described in more detail herein, to estimate flow rates.

[0102] Figure 8A This is an example flowchart illustrating the process for generating a flow estimation signal based on input signals such as gas pressure signals, motor speed signals, and a calculated entrained air density function.

[0103] Figure 8B This is an example flowchart illustrating the process for generating the entrained air density function, in order to produce... Figure 7 The example shows the flow estimation signal.

[0104] Figure 8C It is used in situations such as using Figure 7An exemplary process for using flow estimation signals in the respiratory equipment of an RPT device in a system.

[0105] Figure 9A and 9B This includes graphs illustrating a comparison between flow signals measured by flow sensors and the resulting flow estimation signals, and fan curves of an exemplary RPT device at various heights.

[0106] Figure 10A and 10B This includes graphs illustrating a comparison of flow signals measured by flow sensors and the resulting flow estimation signals during the use of exemplary RPT devices at various altitudes. Detailed Implementation

[0107] Before describing this technology in further detail, it should be understood that this technology is not limited to the specific examples described herein, and the specific examples described herein may be modified. It should also be understood that the terminology used in this disclosure is for the purpose of describing the specific examples described herein only and is not intended to be limiting.

[0108] The following description provides various examples of things that may share one or more common characteristics and / or features. It should be understood that one or more features of any example can be combined with one or more features of other examples. Furthermore, in any example, any single feature or combination of features can form another example.

[0109] 5.1 Treatment

[0110] In one form, the technology includes a method for treating respiratory disorders, the method comprising the steps of delivering air at positive pressure or high flow rate to the inlet 1000 of the patient's airway.

[0111] In some examples of this technique, a positive pressure or high-flow air supply is provided to the patient's nasal passages through one or both nostrils.

[0112] 5.2 Treatment System

[0113] In one form, the technology includes a device or apparatus for treating respiratory disorders. The device or apparatus may include an RPT (Respiratory Pressure Treatment) device 4000 for supplying pressurized air to a patient 1000 via an air circuit 4170 leading to a patient interface 3000. In some forms, the RPT device may be a high-flow-rate treatment device that delivers a controlled flow of air to the patient via an open patient interface (e.g., intubation) at a rate typically higher than the typical inspiratory flow rate.

[0114] 5.3 Patient Interface

[0115] According to one aspect of the present technology, the noninvasive patient interface 3000 includes the following functional aspects: a seal-forming structure 3100, an inflation chamber 3200, a positioning and stabilizing structure 3300, an air vent 3400, a connection port 3600 for connection to an air circuit 4170, and a forehead support 3700. In some forms, the functional aspects may be provided by one or more physical components. In some forms, a single physical component may provide one or more functional aspects. In use, the seal-forming structure 3100 is arranged around the inlet of the patient's airway to facilitate the supply of positive pressure air to the airway. Other patient interface devices may be used depending on the type of treatment provided by the RPT.

[0116] 5.4RPT device

[0117] According to one aspect of the present technology, an RPT device 4000 includes mechanical and pneumatic components 4100, electronic components 4200, and is configured to execute one or more algorithms 4300. The RPT device may have an outer housing 4010, which is configured in two parts: an upper portion 4012 and a lower portion 4014. Furthermore, the outer housing 4010 may include one or more panels 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.

[0118] The pneumatic path of the RPT device 4000 may include one or more air path objects, such as an inlet air filter 4112, an inlet silencer 4122, a pressure generator 4140 (e.g., a blower 4142) capable of supplying positive pressure air, an outlet silencer 4124, and one or more converters 4270, such as a pressure sensor 4272 and a flow sensor 4274.

[0119] One or more air path components may be housed within a detachable, separate structure, referred to as pneumatic block 4020. Pneumatic block 4020 may be housed within an outer housing 4010. In one embodiment, pneumatic block 4020 is supported by, or forms part of, a chassis 4016.

[0120] The RPT device 4000 may include a power supply 4210, one or more input devices 4220, a central controller 4230, a treatment device controller 4240, a pressure generator 4140, one or more protection circuits 4250, a memory 4260, a converter 4270, a data communication interface 4280, and one or more output devices 4290. Electrical components 4200 may be mounted on a single printed circuit board assembly (PCBA) 4202. Alternatively, the RPT device 4000 may include more than one PCBA 4202.

[0121] 5.4.1 Mechanical and pneumatic components of the RPT device

[0122] The RPT device may include one or more of the following components in an integral unit. In an alternative form, one or more of the following components may be configured as separate units.

[0123] 5.4.1.1 Air Filter

[0124] One form of RPT device according to the present technology may include one air filter 4110, or multiple air filters 4110.

[0125] In one configuration, the inlet air filter 4112 is positioned at the beginning of the pneumatic path upstream of the pressure generator 4140.

[0126] In one configuration, an outlet air filter 4114, such as an antibacterial filter, is positioned between the pneumatic block 4020 and the patient interface 3000.

[0127] 5.4.1.2 Muffler

[0128] In one embodiment of this technology, the inlet silencer 4122 is positioned in the pneumatic path upstream of the pressure generator 4140.

[0129] In one embodiment of this technology, the outlet silencer 4124 is disposed in the pneumatic path between the pressure generator 4140 and the patient interface 3000.

[0130] 5.4.1.3 Pressure Generator

[0131] In one form of this technology, the pressure generator 4140 for delivering a flow of air or air supply under positive pressure is a controllable blower 4142. For example, the blower 4142 may include a brushless DC motor 4144 having one or more impellers enclosed in a volute. The blower is capable of delivering an air supply, for example, at a rate up to about 120 liters per minute, under positive pressure ranging from about 4 cmH2O to about 20 cmH2O, or in other forms up to about 30 cmH2O. The blower may be as described in any of the following patents or patent applications, the contents of which are incorporated herein by reference in their entirety: U.S. Patent No. 7,866,944; U.S. Patent No. 8,638,014; U.S. Patent No. 8,636,479; and PCT Patent Application Publication No. WO2013 / 020167.

[0132] The pressure generator 4140 is controlled by the treatment device controller 4240.

[0133] In other words, the pressure generator 4140 can be a piston-driven pump, a pressure regulator (e.g., a compressed air reservoir) connected to a high-pressure source, or a bellows.

[0134] 5.4.1.4 Converter

[0135] The converter can be located inside or outside the RPT device 4000. An external converter can be located on, for example, an air circuit such as a patient interface or form part of it. An external converter can be in the form of a non-contact sensor, such as a Doppler radar motion sensor that transmits data or transfers it to the RPT device.

[0136] In one form of this technology, one or more converters 4270 are located upstream and / or downstream of pressure generator 4140. The one or more converters 4270 may be configured and arranged to measure characteristics such as flow rate, pressure, or temperature at that point in a pneumatic path.

[0137] In one form of this technology, one or more converters 4270 may be located adjacent to the patient interface 3000.

[0138] In one configuration, the signal from converter 4270 can be filtered, such as by low-pass, high-pass, or band-pass filtering.

[0139] 5.4.1.4.1 Flow Sensor

[0140] The flow sensor 4274 according to this technology can be based on a differential pressure converter, such as the SDP600 series differential pressure converter from SENSIRION. In some forms, this technology can be implemented without a flow sensor, such as when a flow estimation signal is generated based on signals from other sensors (i.e., not flow sensor signals).

[0141] In one form, the central controller 4230 receives a signal and / or an estimate of the flow rate, such as the total flow rate Qt from the flow sensor 4274.

[0142] 5.4.1.4.2 Barometric Pressure Sensor

[0143] According to this technology, the pressure sensor 4272 is in fluid communication with the pneumatic path. Therefore, the pressure sensor 4272 measures the pressure characteristics of the gas within the pneumatic path (e.g., the pressure generated by the blower of the RPT). An example of a suitable pressure transducer is the sensor from the HONEYWELL ASDX series. Another suitable pressure transducer is the sensor from the GENERAL ELECTRIC NPA series.

[0144] In one configuration, the signal from pressure sensor 4272 is received by central controller 4230.

[0145] 5.4.1.4.3 Motor Speed ​​Converter

[0146] In one form of this technology, a motor speed converter 4276 or a sensor is used to determine the rotational speed of the motor 4144 and / or the blower 4142. The motor speed signal from the motor speed converter 4276 can be provided to the treatment device controller 4240. The motor speed converter 4276 can be, for example, a speed sensor, such as a Hall effect sensor.

[0147] 5.4.1.4.4 Gas Temperature Sensor

[0148] In some forms of this technology, a gas temperature sensor 4275 is used. In some such implementations, the gas temperature sensor may be a component of another sensor, such as a Sensirion SDP-872 flow sensor (e.g., a hot filament sensor), which can generate temperature and flow signals, but may be a standalone temperature sensor or other temperature sensing device. Such a sensor can generate a measured temperature signal (e.g., electronic) representing the temperature of the gas in or associated with the gas in the pneumatic path of the RPT. This measurement may alternatively represent the gas surrounding the pneumatic flow path of the RPT. For example, such a sensor may be located on the PCB of the RPT. The sensor can generate a sensed temperature in the form of analog and / or digital signals and can be accessed by the processor of the controller 4230 via sampled signals and / or a memory including temperature values ​​from such sensor signals.

[0149] 5.4.1.4.5 Atmospheric Pressure Sensor

[0150] In some forms of this technology, an atmospheric pressure sensor 4277 is used. For example, an atmospheric pressure sensor for the RPT (e.g., on the RPT's PCB) is configured to measure atmospheric pressure (i.e., the pressure outside the RPT's aerodynamic flow path). This sensor can generate sensed atmospheric pressure as an analog and / or digital signal and can be accessed by the processor of the controller 4230 via a sampled signal and / or a memory including atmospheric pressure values ​​from such sensor signals.

[0151] 5.4.1.4.6 Ambient relative humidity sensor

[0152] In some forms of this technology, an ambient relative humidity sensor 4279 is used. For example, a relative humidity sensor for the RPT (e.g., on the RPT's PCB) is configured to measure ambient relative humidity (i.e., the relative humidity outside the RPT's aerodynamic flow path). This sensor can generate a sensed relative humidity in the form of analog and / or digital signals and can be accessed by the processor of the controller 4230 via sampled signals and / or a memory including relative humidity values ​​(such as percentage values) from such sensor signals.

[0153] 5.4.1.4.7 Oxygen Sensor

[0154] Some forms of this technology may optionally include one or more oxygen sensors, such as generating an oxygen sensor signal 7021 adapted to determine the oxygen concentration of a gas passing through a pneumatic path such as an RPT. In one implementation, an oxygen sensor 7023 is used to estimate the oxygen concentration of a gas passing through a breathing duct. An oxygen sensor is a device configured to measure the oxygen concentration in a gas. Examples of oxygen sensors include, but are not limited to, ultrasonic oxygen sensors, electro-oxygen sensors, chemical oxygen sensors, and optical oxygen sensors. In one implementation, oxygen sensor 7023 may be an ultrasonic oxygen sensor comprising an ultrasonic transmitter and an ultrasonic receiver.

[0155] 5.4.1.4.8 Other Motor Parameter Sensors

[0156] Some forms of this technology may optionally include one or more sensors or circuit elements for determining or sensing other motor parameter signals 7021, such as motor current, motor voltage, and / or motor power. For example, one or more sensing resistors may be used to measure the current and / or voltage supplied to the motor of the blower. In some forms, for example using the measured current and the known or measured voltage, the instantaneous power of the motor may be calculated, for example using the central controller of the device (e.g., current x voltage = power).

[0157] 5.4.1.5 Anti-overflow valve

[0158] In one embodiment of this technology, an anti-backflow valve is positioned between the humidifier 5000 and the pneumatic block 4020. The anti-backflow valve is constructed and arranged to reduce the risk of water flowing upstream from the humidifier 5000 to, for example, the motor 4144.

[0159] 5.4.1.6 Air Circuit

[0160] According to one aspect of the technology, the air circuit 4170 is a conduit or tube that is constructed and arranged in use to allow airflow to travel between two components (such as pneumatic block 4020 and patient interface 3000).

[0161] Specifically, the air circuit 4170 can be fluidly connected to the outlet of the pneumatic block and the patient interface. The air circuit may be referred to as an air delivery tube. In some cases, separate branches may exist for the inspiratory and expiratory circuits. In other cases, a single branch is used.

[0162] In some forms, the air circuit 4170 may include one or more heating elements configured to heat air in the air circuit, for example, to maintain or raise the temperature of the air. The heating element may be in the form of a heating wire circuit and may include one or more transducers, such as temperature sensors. In one form, the heating wire circuit may be helically wound around the axis of the air circuit 4170. The heating element may communicate with a controller such as a central controller 4230 or a humidifier controller 5250. An example of an air circuit 4170 including a heating wire circuit is described in U.S. Patent Application US / 2011 / 0023874, which is incorporated herein by reference in its entirety.

[0163] 5.4.1.7 Oxygen Delivery

[0164] In one form of this technology, supplemental oxygen 4180 is delivered to one or more points in a pneumatic path, such as upstream of pneumatic block 4020, and then to air circuit 4170 and / or patient interface 3000.

[0165] 5.4.2 Electrical components of the CPG device

[0166] 5.4.2.1 Power Supply

[0167] The power supply 4210 can be located inside or outside the housing 4010 of the RPT device 4000.

[0168] In one embodiment of this technology, power supply 4210 supplies power only to RPT device 4000. In another embodiment of the invention, power supply 4210 supplies power to both RPT device 4000 and humidifier 5000.

[0169] 5.4.2.2 Input Device

[0170] In one form of this technology, the RPT device 4000 includes one or more input devices 4220 in the form of buttons, switches, or dials to allow human interaction with the device. The buttons, switches, or dials can be physical devices or software devices accessible via a touchscreen. In one form, these buttons, switches, or dials can be physically attached to the outer housing 4010, or in another form, they can be in wireless communication with a receiver electrically connected to a central controller 4230.

[0171] In one form, the input device 4220 may be configured and arranged to allow a person to select values ​​and / or menu options.

[0172] 5.4.2.3 Central Controller

[0173] In one form of this technology, the central controller 4230 is one or more processors adapted to control the RPT device 4000.

[0174] Suitable processors could include x86 Intel processors, based on those from ARM Holdings. The processor can be a processor such as the STM32 series microcontroller from STMicroelectronics. In some alternative forms of this technology, a 32-bit RISC CPU such as the STR9 series microcontroller from STMicroelectronics, or a 16-bit RISC CPU such as the MSP430 series microcontroller from Texas Instruments, may also be used.

[0175] In one form of this technology, the central controller 4230 is a dedicated electronic circuit.

[0176] In one form, the central controller 4230 is an application-specific integrated circuit (ASIC). In another form, the central controller 4230 includes discrete electronic components.

[0177] The central controller 4230 can be configured to receive one or more input signals from one or more converters 4270 and one or more input devices 4220.

[0178] The central controller 4230 can be configured to provide one or more output signals to one or more of the output device 4290, the treatment device controller 4240, the data communication interface 4280, and the humidifier controller 5250.

[0179] In some forms of this technology, the central controller 4230 is configured to implement one or more methods described herein, such as one or more algorithms 4300 represented as a computer program stored in a non-transitory computer-readable storage medium (such as memory 4260). In some forms of this technology, the central controller 4230 may be integrated with the RPT device 4000. However, in some forms of this technology, some methods may be performed by a remotely located device. For example, a remote positioning device may determine the control settings of a ventilator or detect respiratory-related events by analyzing stored data from sensors such as those described herein.

[0180] 5.4.2.4 Clock

[0181] RPT device 4000 may include a clock 4232 connected to central controller 4230.

[0182] 5.4.2.5 Treatment device controller

[0183] In one form of this technology, the treatment device controller 4240 is a treatment control module 4330, which forms part of an algorithm 4300 executed by the central controller 4230.

[0184] In one embodiment of this technology, the treatment device controller 4240 is a dedicated integrated motor control circuit. For example, in one embodiment, an MC33035 brushless DC motor controller manufactured by ONSEMI is used.

[0185] 5.4.2.6 Protection Circuit

[0186] One or more protection circuits 4250 according to the present technology may include electrical protection circuits, temperature and / or pressure safety circuits.

[0187] 5.4.2.7 Memory

[0188] According to one embodiment of the present technology, the RPT device 4000 includes a memory 4260, such as non-volatile memory. In some embodiments, the memory 4260 may include battery-powered static RAM. In some embodiments, the memory 4260 may include volatile RAM.

[0189] The memory 4260 can be located on PCBA 4202. The memory 4260 can be in the form of EEPROM or NAND flash memory.

[0190] Additionally or optionally, the RPT device 4000 includes a removable memory 4260, such as a memory card manufactured according to the Secure Digital (SD) standard.

[0191] In one form of this technology, memory 4260 acts as a non-transitory computer-readable storage medium having computer program instructions stored thereon, the computer program instructions representing one or more methods described herein, including, for example, one or more algorithms 4300 of the method described herein with respect to flow estimation in more detail. Memory 4260 can also act as a volatile or non-volatile storage medium for data that is acquired, collected, used, or generated when one or more processors or methods are executed as instructions by one or more processors.

[0192] 5.4.2.8 Data Communication System

[0193] In one embodiment of this technology, a data communication interface 4280 is provided, and the data communication interface 4280 is connected to a central controller 4230. The data communication interface 4280 can be connected to a remote external communication network 4282 and / or a local external communication network 4284. The remote external communication network 4282 can be connected to a remote external device 4286. The local external communication network 4284 can be connected to a local external device 4288.

[0194] In one embodiment, the data communication interface 4280 is part of the central controller 4230. In another embodiment, the data communication interface 4280 is separate from the central controller 4230 and may include an integrated circuit or a processor.

[0195] In one form, the remote external communication network 4282 is the Internet. The data communication interface 4280 can connect to the Internet using wired communication (e.g., via Ethernet or fiber optic) or wireless protocols (e.g., CDMA, GSM, LTE).

[0196] In one form, the local external communication network 4284 utilizes one or more communication standards, such as Bluetooth or consumer infrared protocols.

[0197] In one form, the remote external device 4286 is one or more computers, such as a networked group of computers. In another 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 can be accessed by a properly authorized person, such as a clinician.

[0198] The local external device 4288 can be a personal computer, mobile phone, tablet computer, or remote control.

[0199] 5.4.2.9 Output devices, including optional displays and alarms.

[0200] The output device 4290 according to this technology can take the form of one or more visual, audio, and tactile units. The visual display can be a liquid crystal display (LCD) or a light-emitting diode (LED) display.

[0201] 5.4.2.9.1 Display Driver

[0202] The driver 4292 receives characters, symbols, or images to be displayed on the monitor 4294 as input and converts them into commands that cause the monitor 4294 to display those characters, symbols, or images.

[0203] 5.4.2.9.2 Monitor

[0204] 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, such as the number "0", into eight logic signals indicating whether to activate eight corresponding segments to display the specific character or symbol.

[0205] 5.4.3 RPT Device Algorithm

[0206] 5.4.3.1 Preprocessing Module

[0207] According to one form of the present technology, a preprocessing module 4310 receives a signal from a converter 4270 (e.g., a flow sensor 4274 or a pressure sensor 4272) as input and performs one or more process steps to calculate one or more output values ​​that will be used as input to another module (e.g., a treatment engine module 4320).

[0208] In one form of this technology, the output values ​​include the interface or mask pressure Pm, the breathing flow rate Qr, and the leakage flow rate Ql.

[0209] In various forms of this technology, the preprocessing module 4310 includes one or more of the following algorithms: pressure compensation 4312, ventilation flow estimation 4314, leakage flow estimation 4316, flow signal estimation 4317, and respiratory flow estimation 4318.

[0210] 5.4.3.1.1 Pressure Compensation

[0211] In one embodiment of this technology, the pressure compensation algorithm 4312 receives a signal indicating the pressure in the pneumatic path near the pneumatic block outlet as input. The pressure compensation algorithm 4312 estimates the pressure drop through the air circuit 4170 and provides an estimated pressure Pm in the patient interface 3000 as output.

[0212] 5.4.3.1.2 Ventilation flow rate estimation

[0213] In one form of this technology, the ventilation flow estimation algorithm 4314 receives the estimated pressure Pm in the patient interface 3000 as input and estimates the air ventilation flow Qv from the air vent 3400 in the patient interface 3000.

[0214] 5.4.3.1.3 Leakage Flow Estimation

[0215] In one form of this technology, the leakage flow estimation algorithm 4316 receives the total flow rate Qt and the ventilation flow rate Qv as inputs and provides an estimate of the leakage flow rate Ql as output. In another form, the leakage flow estimation algorithm 4316 estimates the leakage flow rate Ql by calculating the average of the difference between the total flow rate Qt and the ventilation flow rate Qv over a sufficiently long time period (e.g., about 10 seconds).

[0216] In one form, the leakage flow estimation algorithm 4316 receives the total flow rate Qt, ventilation flow rate Qv, and estimated pressure Pm from the patient interface 3000 as input, and provides the leakage flow rate Ql as output by calculating the leakage conductance and determining the leakage flow rate Ql as a function of the leakage conductance and pressure Pm. The leakage conductance is calculated as the quotient of the difference between the low-pass filtered non-ventilated flow rate Qt and the ventilation flow rate Qv, and the square root of the low-pass filtered pressure Pm, where the low-pass filter time constant has a sufficiently long value to include several respiratory cycles, for example, approximately 10 seconds. The leakage flow rate Ql can be estimated as the product of the leakage conductivity and the pressure Pm.

[0217] 5.4.3.1.4 Respiratory Flow Estimation

[0218] In one form of this technology, the respiratory flow estimation algorithm 4318 receives total flow rate Qt, ventilatory flow rate Qv, and leakage flow rate Ql as inputs, and estimates the patient's air respiratory flow rate Qr by subtracting the ventilatory flow rate Qv and the estimated leakage flow rate Ql from the total flow rate Qt.

[0219] 5.4.3.1.5 Flow Signal Estimation

[0220] In one form of this technique, the flow signal can be estimated by a flow signal estimation algorithm 4317 to generate estimates of the total flow rate Qt, ventilation flow rate Qv, and leakage flow rate Ql, and the patient's airflow rate Qr is further estimated by subtracting the ventilation flow rate Qv and the estimated leakage flow rate Ql from the estimated total flow rate Qt. This flow signal estimation process is described in more detail here. For example, if a fault flow signal is detected during the operation of the flow sensor, such as if a malfunction is detected in the operation of the flow sensor. Similarly, this flow signal estimation can be used to detect malfunctions in the operation of the flow sensor, or to evaluate the accuracy of the flow sensor, as discussed in more detail herein.

[0221] 5.4.3.2 Healing Engine Module

[0222] In one form of this technology, the treatment engine module 4320 receives one or more of the pressure Pm in the patient interface 3000 and the respiratory flow rate Qr of the air to the patient as input, such as one derived from a flow estimation signal, and provides one or more treatment parameters as output.

[0223] In one form of this technique, the treatment parameter is the treatment pressure Pt.

[0224] In various forms, the treatment engine module 4320 includes one or more of the following algorithms: phase determination 4321, waveform determination 4322, ventilation determination 4323, inspiratory flow restriction detection 4324, apnea detection 4325, inspiratory M-shaped detection 4326, airway patency determination 4327, typical recent ventilation determination 4328, and treatment parameter determination 4329.

[0225] 5.4.3.2.1 Phase Determination

[0226] In one form of this technology, the phase determination algorithm 4321 receives a signal indicating respiratory flow Qr as input and provides the phase of the patient's current respiratory cycle as output.

[0227] In some forms known as discrete phase determination, the phase output is a discrete variable. One implementation of discrete phase determination provides a dual-valued phase output with either an inspiratory or expiratory value, for example, values ​​of 0 and 0.5 revolutions, respectively, when the start of spontaneous inspiration and expiration is detected, respectively. The “triggering” and “cycling” RPT device 4000 effectively performs discrete phase determination because the trigger and cycling moments are the moments when the phase changes from expiration to inspiration and from inspiration to expiration, respectively. In one implementation of dual-valued phase determination, the phase output is determined to have a discrete value of 0 (indicating inspiration) when the respiratory flow Qr exceeds a “trigger threshold” (thus triggering the RPT device 4000 to deliver “spontaneous breathing”), and a discrete value of 0.5 revolutions (indicating expiration) when the respiratory flow Qr falls below a “cycling threshold” (thus triggering the RPT device 4000 to “spontaneously cycle”). In some such implementations, the trigger threshold and cycling threshold can vary over time during respiration according to corresponding trigger threshold and cycling threshold functions. These features are described in ResMed Limited’s Patent Cooperation Treaty patent application number PCT / AU2005 / 000895 (published as WO 2006 / 000017), the entire contents of which are incorporated herein by reference.

[0228] In some such implementations, the loop may be blocked during a "refractory period" (denoted as Timen) after the last triggering moment, and in the absence of a spontaneous loop, it must occur within a interval (denoted as Timex) after the last triggering moment. The values ​​of Timin and Timax are settings of the RPT device 4000 and can be set, for example, by hardcoding during the configuration of the RPT device 4000 or by manual input via the input device 4220.

[0229] In other forms known as continuous phase determination, the phase output is a continuous variable, such as varying from 0 to 1 revolution or 0 to 2 radians. The RPT device 4000 performing continuous phase determination can be triggered and cycled when the continuous phase reaches 0 and 0.5 revolutions, respectively. In one implementation of continuous phase determination, the inspiratory time Ti and expiratory time Te are first estimated based on the respiratory flow rate Qr. The phase is then determined as either half the proportion of the inspiratory time Ti elapsed since the previous triggering moment, or 0.5 revolutions plus half the proportion of the expiratory time Te elapsed since the previous cycle moment (whichever is more recent).

[0230] In some implementations suitable for ventilation therapy (described below), the phase determination algorithm 4321 is configured to trigger even when the respiratory flow Qr is not significant (such as during apnea). As a result, the RPT device 4000 delivers "backup breaths" in the absence of spontaneous breathing from the patient 1000. For this form, referred to as spontaneous / timed (ST) mode, the phase determination algorithm 4321 may utilize a "backup rate" Rb. The backup rate Rb is a setting of the RPT device 4000 and can be set, for example, by hardcoding during the configuration of the RPT device 4000 or by manual input via the input device 4220.

[0231] The phase determination algorithm 4321 (discrete or continuous) can implement the ST mode using a backup rate Rb in a manner referred to as timed backup. Timed backup can be implemented as follows: The phase determination algorithm 4321 attempts to detect the onset of inspiration due to spontaneous breathing effort, for example, by comparing the respiratory flow rate Qr with the trigger threshold as described above. If no onset of spontaneous inspiration is detected within an interval (referred to as the interval of the backup timing threshold Tback) after the last trigger moment of the duration equal to the reciprocal of the backup frequency Rb or the reciprocal of the last trigger moment, the phase determination algorithm 4321 sets the phase output to a value of 0, thereby triggering the RPT device 4000 to deliver a backup breath. Then, the phase determination algorithm 4321 attempts to detect the onset of spontaneous exhalation, for example, by comparing the respiratory flow rate Qr with the cycle threshold as described above. The cycle threshold for backup breathing can be different from the cycle threshold for spontaneous breathing. Similar to spontaneous breathing, spontaneous cycles during backup breathing can be prevented during the "refractory period" of the duration Timin after the last trigger moment.

[0232] Similar to spontaneous breathing, if no start of spontaneous exhalation is detected within Timax seconds after the previous trigger moment during the standby breathing period, the phase determination algorithm 4321 sets the phase output to a value of 0.5, thereby causing the RPT device 4000 cycles. The phase determination algorithm 4321 then attempts to detect the start of spontaneous inhalation by comparing the respiratory flow rate Qr with the trigger threshold as described above.

[0233] 5.4.3.2.2 Waveform Determination

[0234] In one form of this technology, waveform determination algorithm 4322 provides approximately constant therapeutic pressure throughout the patient's respiratory cycle.

[0235] In other forms of this technology, waveform determination algorithm 4322 controls pressure generator 4140 to provide therapeutic pressure Pt that varies throughout the patient's respiratory cycle according to a waveform template.

[0236] In one form of this technology, the waveform determination algorithm 4322 provides a waveform template Π(Φ) having a value in the range [0, 1] over the domain of the phase value Φ provided by the phase determination algorithm 4321 for use by the waveform determination algorithm 4322.

[0237] In one form, suitable for discrete or continuous phase values, the waveform template Π(Φ) is a square wave template with a value of 1 for phase values ​​up to and including 0.5 revolutions and a value of 0 for phase values ​​greater than 0.5 revolutions. In another form, suitable for continuous phase values, the waveform template Π(Φ) includes two smooth curve portions: for phase values ​​up to 0.5 revolutions, the smooth curve (e.g., raised cosine) rises from 0 to 1, while for phase values ​​greater than 0.5 revolutions, the smooth curve (e.g., exponential) falls from 1 to 0.

[0238] In some forms of this technology, the waveform determination algorithm 4322 selects a waveform template Π(Φ) from a waveform template library according to the settings of the RPT device 4000. Each waveform template Π(Φ) in the library may be provided as a lookup table of value Π relative to 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, which may be parameterized by one or more parameters (e.g., rise time and fall time). The parameters of the functional form may be predetermined or dependent on the current state of the patient 1000.

[0239] In some forms of this technology, waveform determination algorithm 4322 is applicable to discrete two-valued phases of inhalation (Φ = 0 rpm) or exhalation (Φ = 0.5 rpm). Waveform determination algorithm 4322 calculates a “running” waveform template Π as a function of the discrete phase Φ and the time t measured since the most recent trigger moment. In one such form, waveform determination algorithm 4322 calculates the waveform template Π(Φ,t) for two parts (inhalation and exhalation) as follows:

[0240]

[0241] Among them Π i (t) and Π e(t) represents the inhalation and exhalation portions of the waveform template Π(Φ,t).

[0242] In one such form, the air intake portion Π of the waveform template i (t) smoothly rises from 0 to 1 in two consecutive parts:

[0243] ● For the first half of the parameter, called the “time scale”, it rises linearly to 2 / 3;

[0244] ●For the latter half of the time scale, the parabola rises to 1.

[0245] This inhalation part Π i (t) "Rise time" can be defined as Π i The time it takes for (t) to rise to a value of 0.875.

[0246] The exhalation portion of the waveform template Π e (t) represents a smooth decrease from 1 to 0 in two consecutive parabolic segments, with the inflection point between 25% and 50% of the time scale. This exhalation segment Π e The "descent time" of (t) can be defined as Π e The time it takes for (t) to drop to a value of 0.125.

[0247] 5.4.3.2.3 Ventilation Determination

[0248] In one form of this technology, ventilation determination algorithm 4323 receives an input respiratory flow rate Qr, which can be derived from the estimated flow signal as described above, and determines a measurement Vent indicating the current patient ventilation.

[0249] In some implementations, the ventilation determination algorithm 4323 calculates Vent as "instantaneous ventilation" Vint, which is half the absolute value of the respiratory flow signal Qr.

[0250] In some implementations, the ventilation determination algorithm 4323 calculates Vent as a “very fast ventilation” VveryFast by filtering the instantaneous ventilation Vint with a low-pass filter (such as a fourth-order Bessel low-pass filter with a corner frequency of about 0.10 Hz). This is equivalent to a time constant of about 10 seconds.

[0251] In some implementations, the ventilation determination algorithm 4323 calculates Vent as the "fast ventilation" Vfast by filtering the instantaneous ventilation Vint with a low-pass filter (such as a fourth-order Bessel low-pass filter with a corner frequency of about 0.05 Hz). This is equivalent to a time constant of about 20 seconds.

[0252] In some implementations of this technology, the ventilation determination algorithm 4323 determines Vent as a measurement of alveolar ventilation. Alveolar ventilation is a measurement of how much air actually reaches the gas exchange surfaces of the respiratory system within a given time. Because a patient's respiratory system includes significant "anatomical dead space," i.e., the volume in which no gas exchange occurs, alveolar ventilation is less than the "total" ventilation value that would be produced by directly calculating the respiratory flow rate Qr, but it is a more accurate measurement of the patient's respiratory performance.

[0253] In this implementation, ventilation determination algorithm 4323 can determine whether the instantaneous alveolar ventilation is zero or half the absolute value of the respiratory flow rate Qr. The condition for zero instantaneous alveolar ventilation is:

[0254] ●When respiratory flow changes from non-negative to negative, or

[0255] ●When respiratory flow changes from negative to non-negative, and

[0256] ●The time period during which the absolute value of the integral of the respiratory flow rate Qr is less than the patient's anatomical dead space volume after the sign of the respiratory flow rate has changed.

[0257] The patient's anatomical dead space volume can be set by the RPT device 4000, for example, by hard coding during the configuration of the RPT device 4000 or by manual input via the input device 4220.

[0258] In some such implementations, the ventilation determination algorithm 4323 can calculate ventilation as “very fast alveolar ventilation” and / or “rapid alveolar ventilation” by using the corresponding low-pass filter described above to low-pass filter the transient alveolar ventilation.

[0259] The term "alveolar" is omitted in the following text, but it can be assumed that it exists in some implementations of the treatment engine module 4320. That is, "ventilation" and "tidal volume" mentioned in the following description can be used for alveolar ventilation and alveolar tidal volume, as well as "total" ventilation and tidal volume.

[0260] 5.4.3.2.4 Determination of Inspiratory Flow Restriction

[0261] In one form of this technology, the treatment engine module 4320 executes one or more algorithms to determine the degree of flow restriction in the inspiratory portion of a respiratory flow waveform, sometimes referred to as partial upper airway obstruction (sometimes simply referred to herein as the “inspiratory waveform”). In one form, the flow restriction determination algorithm 4324 receives a respiratory flow signal Qr as input, which can be derived from the estimated flow signal as described above, and provides a measurement as output of the degree of flow restriction exhibited by each inspiratory waveform.

[0262] A normal inspiratory waveform is circular, and its shape is close to a sine curve (see...). Figure 6A With sufficient upper airway muscle tone (or EPAP), the airway essentially functions as a rigid tube, where flow increases in response to increased respiratory effort (or external ventilation assistance). In some cases (e.g., sleep, sedation), the upper airway can be collapsible, such as in response to respiratory effort or even subatmospheric pressure within the upper airway from the applied ventilation. This can lead to complete obstruction (apnea) or a phenomenon known as “flow restriction.” The term “flow restriction” includes behavior in which increased respiratory effort merely causes an increase in airway narrowing, such that inspiratory flow becomes restricted to a constant value, independent of effort (“Starling resistance behavior”). Therefore, the inspiratory flow curve exhibits a flat shape (see [link to relevant documentation]). Figure 6B ).

[0263] In fact, upper airway behavior is even more complex, with a wide variety of flow patterns indicating upper airway-related inspiratory flow limitations, and an even wider variety of flow patterns in the presence of external ventilation assistance (see Appendix). Figure 6C to 6F Therefore, the flow restriction determination algorithm 4324 can respond to one or more of the following types of inspiratory flow restrictions: "classical smoothness" (see...). Figure 6B "Height" (see Figure 6C ) and "reverse height" (see Figure 6D ("M-shape" (see "M-shape")) Figure 6E and 6F The M-shaped detection algorithm 4326 is used.

[0264] 5.4.3.2.5 M-shape detection

[0265] In one form of this technology, the treatment engine 4320 module executes one or more algorithms to detect an "M-shape" in the inspiratory waveform. In one form, the M-shape detection algorithm 4326 receives the respiratory flow signal Qr as input and provides a measurement indicating the degree to which each inspiratory waveform exhibits an M-shape as output.

[0266] An M-shaped inspiratory waveform where tidal volume or other respiratory ventilation values ​​are not far from typical recent values ​​indicates flow restriction. This inspiratory waveform has a relatively rapid rise and fall, and a drop or "notch" in flow approximately in the center, which is due to flow restriction (see [link to relevant documentation]). Figure 6E and 6F At higher tidal volumes or respiratory ventilation values, this waveform is typically behavioral, i.e., micro-awakening during sleep or sighing, and without flow restriction.

[0267] To detect the M-shaped waveform, the M-shaped detection algorithm 4326 determines the similarity between the inhalation waveform and the approximate M-shaped waveform.

[0268] 5.4.3.2.6 Apnea Detection

[0269] In one form of this technology, the treatment engine module 4320 executes the apnea detection algorithm 4325 to detect apnea.

[0270] In one form, the apnea detection algorithm 4325 receives a respiratory flow signal Qr as input and provides a series of events indicating the start and end of a detected apnea as output.

[0271] 5.4.3.2.7 Determination of Typical Short-Term Ventilation

[0272] In one form of this technology, the central controller 4230 takes the current ventilation measurement value Vent as input and executes one or more typical recent ventilation determination algorithms 4328 to determine a value Vtyp indicating the typical recent ventilation of patient 1000.

[0273] A typical recent ventilation volume, Vtyp, is a value around which the distribution of current ventilation volume (Vent) measurements at multiple moments on a predetermined time scale tends to cluster; that is, the measurement of the current ventilation volume shows a central tendency over recent history. In one implementation of the typical target ventilation volume determination algorithm 4328, the recent history is on the order of minutes, but should in any case be longer than the time scale of Cheyne-Stokes waxing and waxing cycles. The typical recent target ventilation volume determination algorithm 4328 can use any of a variety of well-known central tendency measurements to determine the typical recent ventilation volume Vtyp based on the current ventilation volume (Vent) measurement. One such measure is to output a low-pass filter on the current ventilation volume measurement with a time constant of one hundred seconds.

[0274] 5.4.3.2.8 Determining airway patency

[0275] In one form of this technology, the central controller 4230 executes an airway patency determination algorithm 4327 to determine airway patency. In some implementations, the airway patency determination algorithm 4327 returns "closed" or "open" or an equivalent Boolean value, such as "true" indicating closed and "false" indicating open.

[0276] 5.4.3.2.9 Determination of Treatment Parameters

[0277] In some forms of this technology, the central controller 4230 executes one or more treatment parameter determination algorithms 4329 to determine one or more treatment parameters using values ​​returned by one or more other algorithms in the treatment engine module 4320.

[0278] In one form of this technology, the treatment parameter is the instantaneous treatment pressure Pt. In one implementation of this form, the treatment parameter determination algorithm 4329 uses the following equation to determine the treatment pressure Pt:

[0279] Pt=AΠ(Φ,t)+P0 (1)

[0280] Where A is the quantity of "pressure support", Π(Φ,t) is the waveform template value (in the range of 0 to 1) at the current value of phase Φ and the current value of time t, and P0 is the base pressure.

[0281] By using equation (1) to determine the treatment pressure Pt and applying it as a setpoint in the controller 4230 of the RPT device 4000, the treatment parameter determination algorithm 4329 synchronizes the treatment pressure Pt with the spontaneous respiratory effort of the patient 1000. That is, based on the typical waveform template Π(Φ) described above, the treatment parameter determination algorithm 4329 increases the treatment pressure Pt at the beginning of inspiration or during inspiration, and decreases the treatment pressure Pt at the beginning of expiration or during expiration. The (non-negative) pressure support A is the amplitude of the oscillation.

[0282] If the waveform determination algorithm 4322 provides a waveform template Π(Φ) as a lookup table, the treatment parameter determination algorithm 4329 applies equation (1) by locating the lookup table entry that is closest to the current value Φ of the stage returned by the stage determination algorithm 4321, or by interpolating between two entries that span the current value Φ of the stage.

[0283] The values ​​of pressure support A and baseline pressure P0 can be determined by treatment parameter determination algorithm 4329 in the manner described below, based on the selected respiratory pressure treatment mode.

[0284] 5.4.3.3 Treatment Control Module

[0285] According to one aspect of the present technology, the treatment control module 4330 receives treatment parameters from the treatment parameter determination algorithm 4329 of the treatment engine module 4320 as input, and controls the pressure generator 4140 to deliver an airflow according to the treatment parameters.

[0286] In one form of this technology, the treatment parameter is the treatment pressure Pt, and the treatment control module 4330 controls the pressure generator 4140 to deliver an airflow, the airflow having a mask pressure Pm at the patient interface 3000 equal to the treatment pressure Pt, or the airflow having an interface flow rate Ft at the interface equal to the treatment flow rate TFt.

[0287] 5.4.3.4 Detecting Fault Conditions

[0288] In one form of this technology, the central controller executes one or more methods 4230 for detecting fault conditions. The fault conditions detected by the one or more methods may include at least one of the following:

[0289] ● Power failure (no power or insufficient power)

[0290] ● Converter fault detection

[0291] ●Unable to detect the presence of components

[0292] ● Operating parameters outside the recommended range (e.g., pressure, flow rate, temperature, PaO2).

[0293] ● The test alarm failed to generate a detectable alarm signal.

[0294] ● Significant inhomogeneity between the flow signal from the flow sensor and the flow estimation signal from the flow signal estimation process 4137.

[0295] When a fault condition is detected, the corresponding algorithm notifies the existence of the fault by sending one or more of the following signals:

[0296] ●Activate audible, visual, and / or dynamic (e.g., vibration) alarms.

[0297] ● Sending messages to external devices

[0298] ● Event logging

[0299] ● Changes in control parameters as described in more detail in this article

[0300] 5.5 Humidifier

[0301] In one form of this technology, a humidifier 5000 is provided (e.g., as in...). Figure 5A (As shown) to change the absolute humidity of the air or gas delivered to the patient relative to the ambient air. Typically, the humidifier 5000 is used to increase the absolute humidity of the airflow and increase the temperature of the airflow (relative to ambient air) before it is delivered to the patient's airway.

[0302] The humidifier 5000 may include a humidifier reservoir 5110, a humidifier inlet 5002 for receiving an airflow, and a humidifier outlet 5004 for delivering the humidified airflow. In some forms, such as Figure 5A and Figure 5B As shown, the inlet and outlet of the humidifier reservoir 5110 can be a humidifier inlet 5002 and a humidifier outlet 5004, respectively. The humidifier 5000 may also include a humidifier base 5006, which is adapted to receive the humidifier reservoir 5110 and includes a heating element 5240.

[0303] 5.6 Respiratory Pressure Therapy Mode

[0304] Based on the values ​​of parameters A and P0 in the treatment pressure equation (1) used by the treatment parameter determination algorithm 4329 in one form of this technology, the RPT device 4000 can realize various respiratory pressure treatment modes.

[0305] 5.6.1 CPAP Treatment

[0306] In some implementations, the pressure support A is also zero, so the treatment pressure Pt is equal to the baseline pressure P0 throughout the respiratory cycle. This implementation is typically grouped under the heading of CPAP therapy. In these implementations, the treatment engine module 4320 is not required to determine the phase Φ or waveform template Π(Φ).

[0307] 5.6.2 Ventilation therapy

[0308] In other implementations, the value of pressure support A in equation (1) can be positive. This implementation is referred to as ventilation therapy. In some forms of ventilation therapy known as fixed pressure support ventilation therapy, pressure support A is fixed at a predetermined value, such as 10 cmH2O. This predetermined pressure support value is a setting of the RPT device 4000 and can be set, for example, by hard coding during the configuration of the RPT device 4000 or by manual input via input device 4220. In some forms, the pressure can be bi-level, such as delivering a higher pressure during the patient's inspiration and a lower pressure during the patient's expiration.

[0309] The pressure support value A can be limited to a range defined as [Amin, Amax]. The pressure support limits Amin and Amax are settings of the RPT device 4000, for example, by hard-coding during the configuration of the RPT device 4000 or by manual input via the input device 4220. The minimum pressure support Amin of 3 cmH2O is approximately 50% of the pressure support required to perform all respiratory work of a typical patient in steady state. The maximum pressure support Amax of 12 cmH2O is approximately twice the pressure support required to perform all respiratory work of a typical patient, thus sufficient to support the patient's breathing if the patient stops making any effort, but values ​​below which would be uncomfortable or dangerous.

[0310] 5.7 Respiratory Flow Therapy Mode

[0311] In some forms, RPT can be configured with a flow control loop, such as an estimated flow signal, to provide respiratory therapy with an interface to the patient's airway that is 'open' (unsealed). The respiratory therapy can supplement the patient's own spontaneous breathing with a controlled, regulated, or concentrated gas flow. In one example, high-flow therapy (HFT) controls the airway inlet through an unsealed or open patient interface to maintain a substantially constant "therapeutic flow rate" throughout the respiratory cycle. This therapeutic flow rate is nominally set to exceed the patient's peak inspiratory flow rate. As an alternative to a constant flow rate, the therapeutic flow rate can follow a curve that varies over the respiratory cycle.

[0312] 5.8 Flow Signal Estimation

[0313] As previously mentioned, a controller or processor, such as one or more RPTs, can be implemented, for example, without utilizing signals from a flow sensor. Figure 4D The flow signal estimation is achieved through the process 4317. Figure 7An exemplary flow estimation process is illustrated in estimation process 7002. As shown, the process may include a flow estimation unit 7004, such as a central controller or processor using control logic or processor control instructions as described above, which implements a function including flow estimation to derive a flow estimation signal 7008 from a set of input signals 7010, which may include measurements from a set of sensors. In this example, the flow estimation unit 7004 may receive signals (e.g., access data values ​​from memory and / or more directly from sensors) to generate the flow estimation signal 7008. As shown, input signals may include pressure 7012, such as from a pressure sensor 4272 in the pneumatic path of the RPT, to be associated with the operation of the blower. Input signals may include motor speed 7014, such as from a speed converter 4276, which may be associated with the motor of the blower of the RPT. Input signals may include atmospheric pressure 7016, such as atmospheric pressure from an atmospheric pressure sensor 4277, which may be configured to measure ambient pressure. Input signals may include gas temperature 7018, such as gas temperature from gas temperature sensor 4275, which may be associated with gas within the pneumatic path of the RPT. Input signals may include ambient relative humidity 7020, such as ambient relative humidity from ambient relative humidity sensor 4279, which may be associated with gas outside the pneumatic path of the RPT (e.g., the environment). In some forms, input signals may also optionally include signals from oxygen sensors (e.g., oxygen concentration 7021) and / or from motor parameter sensors (e.g., motor parameter 7023). Input signals may be received from sensors in real-time or near real-time to generate flow estimation signals simultaneously and repeatedly over time. Furthermore, in some forms, this estimation signal process may utilize one, more, or all of these signals from stored values ​​in memory.

[0314] In some examples, the flow estimation unit 7004 can achieve... Figure 8A and 8B The flowchart illustrates one or more processes. Furthermore, the flow estimation unit 7004 can operate in conjunction with the treatment engine and / or fault condition detection 4340 process to achieve... Figure 8C The method shown. For example, as Figure 8AAs shown, in step or process 8002, the flow estimation unit 7004 may receive input signals, such as measured atmospheric pressure signals and measured motor speed signals, such as using one or more sensors, and optionally other input signals previously described. In step or process 8004, the flow estimation unit 7004 may calculate an entrained air density function. In step or process 8006, the flow estimation unit 7004 may generate a flow estimation signal 7008, such as a flow estimation function having a function using gas pressure, motor speed, and entrained air density. Optionally, such as in the process of combining the flow estimation unit with a treatment engine or a fault condition detection engine, at process or step 8008, the central controller may generate an output indicator based on the generated flow estimation signal and / or an estimate of the estimation signal. In some forms, the flow estimation may optionally be derived with other motor parameters (e.g., motor power) to generate the estimated flow signal, such as those described in U.S. Patent No. 6,237,593 to Brydon (ResMed Limited). For example, when the system flow is negative (e.g., from a patient interface such as a patient moving in one direction toward a flow generator blower), this estimated flow signal can be utilized.

[0315] In some forms, when determining the estimated flow rate, signals such as those from an oxygen sensor can be used to assess the oxygen concentration to account for the concentration of the breathable gas being sensed. For example, if the gas composition of the breathable gas in the system differs from or is significantly different from ambient air, the function used to generate the estimated flow signal can be modified to account for this difference, or the existing function can be abandoned because the gas may differ from what is expected (e.g., the gas differs from the ambient air used in the model to derive the entrained air density function). In some examples, multiple entrained air density functions, as described herein by empirical models, can be derived at design time, each using a different gas concentration. Thus, in some forms, signals from an oxygen sensor can be used to select a suitable entrained air density function from multiple functions based on the gas concentration measured by the oxygen sensor during runtime, such that the selected function(s) is previously derived empirically using similar or equivalent gas concentrations (e.g., using fan curves).

[0316] Therefore, in some forms, the realization of a flow estimation function, such as when the system flow is positive (e.g., moving in one direction from the flow generator fan to the patient interface (such as the vent to the patient and the patient interface), can be calculated according to the following equation / function, which is a function of pressure, velocity, and atmospheric density:

[0317]

[0318] in:

[0319] Flow_est is the generated flow estimation signal;

[0320] A, B, and C are each frequency-dependent functions of a set of functions, such as at least the rotational frequency (e.g., the measured motor speed); and

[0321] Pressure_meas is a measurement of the pressure generated by the blower, such as that obtained by pressure sensor 4272 within the pneumatic path of the RPT.

[0322] In such an example, the set of functions for rotation frequency can be implemented as follows:

[0323]

[0324] B = -r3 * RPM 2 -r4*RPM-r5

[0325]

[0326] in:

[0327] r1, r2, r3, r4, r5, r6, and r7 are constants;

[0328] RPM is a measurement of motor speed (e.g., revolutions per minute); and

[0329] Furthermore, it includes an air density function or can be derived using such a function. These can include the ratio of a reference atmospheric density to a local atmospheric density, and can be as described in this paper regarding... Figure 8B The exemplary process is calculated as described in more detail. Each such ratio achieved in the generation of the flow estimation signal can be considered a density correction factor. The reference air density can be the air density that exists when the fan curves required for model building have been recorded. The density correction factor, in particular its local atmospheric density, can be empirically determined by evaluating one or more fan curves, such as at the same speed but different altitudes, as described in more detail herein, such as gases with a specific oxygen concentration (e.g., ambient air or others).

[0330] In an exemplary implementation, the constants of the rotational frequency correlation functions (A, B, C) can be determined empirically using fan curves (one or more) at different altitudes and correlated with the operation of the RPT blower (e.g., using at least part of pressure, flow, and RPM measurements) and modeled using polynomials (e.g., using second-order polynomial equations). For example, these values ​​can be found empirically by comparing fan curves at sea level, 2000m, and 3000m altitudes (e.g., at 5000, 10000, 15000, and 20000 RPM), such as using a barometer. In one such example, these constants could be the following values: 0.00000001, 0.00086500, 0.00000000005, 0.0000005119, 0.0130975, 0.000000038, 0.000070756, and 0.281905000. However, it is understood that these constant values ​​can vary depending on the type and construction of the blower in the RPT device. Furthermore, the values ​​of these constants can, for example, be approximated or otherwise rounded to the appropriate number desired for any particular implementation.

[0331] As previously described, the flow estimation unit 7004 employs an entrained air density function, which correlates a reference atmospheric density value with a locally determined atmospheric density value. This functionality can utilize measurement signals from a set of sensors, such as data representing these signals from a memory, including, for example, a gas temperature sensor 4275, an atmospheric pressure sensor 4277, and a relative humidity sensor.

[0332] Figure 8B The implementation is shown in the figure. Figure 8A This is an exemplary process for this function of process or step 8004. In process or step 8022, the central controller or processor may receive signals representing gas temperature, atmospheric pressure, and relative humidity. At process or step 8024, the central controller or processor may calculate, for example, a saturated vapor pressure function (Psv) related to temperature, which may use the measured temperature. At process or step 8026, the central controller or processor may calculate a vapor pressure function (Pv), such as with respect to temperature and relative humidity, which may use the measured relative humidity. This function may employ the saturated vapor pressure function (Psv), such that the vapor pressure function (Pv) is also a function of temperature. In process or step 8026, the central controller or processor may calculate an atmospheric density value based on the vapor pressure function (Pv), the saturated vapor pressure function (Psv), and the atmospheric pressure signal.

[0333] For example, in some forms, the saturated vapor pressure function (Psv) can be implemented as follows:

[0334]

[0335] in:

[0336] Psv is the value of the saturated vapor pressure generated by the saturated vapor pressure function;

[0337] e is the Euler number or any other value that approximates such a number to the desired number of digits;

[0338] Temp local_DegC This includes temperature measurements such as those in Celsius or other suitable temperature measures; and

[0339] K1, K2, and K3 are constants that can be determined empirically, but in some forms they can be, for example, 6.1078, 17.2693882, and 237.4, respectively. These values ​​can be approximated or otherwise rounded to the appropriate number of digits desired for any particular implementation.

[0340] In some forms, the vapor pressure function (Pv) can be implemented as follows:

[0341] Pv=RH local *Psv

[0342] in:

[0343] Pv is the value of vapor pressure generated by the vapor pressure function;

[0344] RH local It is the measured relative humidity, such as a signal from the ambient relative humidity sensor 4279, which can be a percentage; and

[0345] Psv is the value of the saturated vapor pressure generated by the saturated vapor pressure function.

[0346] In some forms, when calculating local air density values, the entrained air density function, as a function of atmospheric pressure, gas temperature, and relative humidity, can be implemented as follows:

[0347]

[0348] in:

[0349] ρ local These include, for example, the local air density values ​​used to calculate the aforementioned ratios;

[0350] P0 is 1013.0 hectopascals;

[0351] T0 is 15.0 degrees Celsius or 288.15 Kelvin;

[0352] ρ0 is

[0353] Patm_local It is a measurement of atmospheric pressure, such as a signal generated by atmospheric pressure sensor 4277;

[0354] Z1 is a constant that can be determined empirically, and in some forms it can be, for example, 0.3783 or other approximations thereof, such as rounded to the desired number of numbers expected by any particular implementation;

[0355] Temp local_DegK Temperature measurements such as those in Kelvin or other suitable temperature measures; and

[0356] Pv is the vapor pressure value generated by the vapor pressure function.

[0357] This generated flow estimation signal can be implemented by a controller (e.g., a central controller) or a processor (such as the processor of an RPT device) to perform various operations, such as for device diagnostics (e.g., fault detection). Additionally, estimation signals for control and / or respiratory status detection can be generated, replacing or appending to the flow estimation signal generated by the flow sensor. This can be discussed as previously mentioned. Figure 8A The above is mentioned and shown in more detail. Figure 8C The example steps or process 8008 are examples of such automated operations.

[0358] For example, in step or process 8030, the controller or processor may optionally receive a measured flow signal from flow sensor 4274. In step or process 8031, the controller or processor may receive a flow estimation signal 7008 from flow estimation process 7002. In step or process 8032, the controller or processor may evaluate the flow estimation signal 7008. For example, in some forms, such evaluation may involve any method described herein or otherwise known related to the analysis of the flow signal from the flow sensor, but alternatively using the flow estimation signal. For example, the estimation signal may be evaluated to determine the onset of patient inspiration, such as for triggering IPAP, for the onset of patient expiration in cyclic EPAP, or for determining phase variables as described herein. In some forms, the flow estimation signal may be evaluated relative to the measured flow signal. For example, the flow estimation signal may be used as a diagnostic check on the measured flow signal. For example, the controller or processor may compare the two signals and generate an indicator such as an error, fault, or missing fault indicator based on the comparison. In one such form, if one or more differences along different times of the signal are significant, such as relating to one or more thresholds, the controller or processor can generate a fault signal. The absence of significant differences can be used to confirm that the flow sensor is not faulty, and an appropriate signal can be generated to allow operation dependent on the flow sensor as an input signal for any method / process as described above.

[0359] Optionally, the output from process 8034, such as an error signal or fault signal, can be applied at step or process 8036 to control the respiratory equipment, such as an RPT device, to change operation, stop operation, or trigger a warning or alarm for an error (e.g., an audible, visual, or communication message). In some such examples, such output can be reported on a diagnostic display to show a fault error in the flow sensor or to depict the relationship between the estimated signal and the measured signal. This can be combined with... Figure 9A - Figure 9B and Figure 10A - Figure 10B The graph is shown as a comparative example.

[0360] As a further example, the operating mode of the RPT can be altered using an indication of a flow sensor malfunction, allowing it to avoid dependence on the flow signal. In some such control configurations, this activated flow estimation operating mode of the RPT can process the flow estimation signal instead of the measured flow signal. In some such configurations, the controller can determine ventilation control parameters such as measurements of patient ventilation (e.g., tidal volume, minute ventilation, etc.) to achieve controlled ventilation targets for pressure support adjustments. As a further example, respiratory rate and respiratory flow can be determined based on the estimated signal. Additionally, pressure and / or flow control parameters, such as the pressure of the controller for the RPT or the pressure and / or flow control parameters of the flow control loop, can be modified based on the flow estimation signal. In some such configurations, the detected difference between the estimated signal and the measured flow signal can be applied as an error signal to calibrate the flow sensor. For example, this difference or error can be applied to adjust the measured value from the flow sensor, such that the calibrated / adjusted measured flow signal can be used throughout any control process of the controller for the RPT described in this specification. This calibration process can be performed periodically by the device during the initialization process when the RPT is activated before a treatment session and / or before a use session.

[0361] Other operations using the flow estimation signal can also be implemented by the controller or processor. It can serve as a substitute for using flow sensor signals and all other measures or characteristics that would otherwise use the flow sensor signal as input. For example, a conductance-based circuit breaker alarm can be implemented using this flow estimation signal instead of a flow sensor signal. Thus, the conductance is used as the basis for detecting the breaker condition, calculated based on the measured pressure signal and the estimated flow signal (e.g., the ratio of the values ​​of these signals). Furthermore, in some forms, the flow estimation signal can be used in flow control loops with a target flow rate (e.g., therapeutic flow rate), such as in an RPT configured as a high-flow-rate treatment device. In this way, it can serve as a substitute for providing a flow sensor (i.e., the flow sensor can be omitted), or as a backup in case the included flow sensor fails.

[0362] The accuracy of this flow estimation signal based on the above method can be compared with... Figure 9A - Figure 9B and Figure 10A - Figure 10B The measured flow rate signal in the curve is considered in comparison. Figure 9A and 9B In the diagram, the fan curves for measuring flow rate and estimating flow are plotted relative to the blower speed of the RPT at different heights. Figure 9A The data shown is from the device operating at an altitude of 2000 meters. Figure 9B Data from the apparatus operated at an altitude of 3000 meters are shown. As shown in the figure, the estimated flow curve closely approximates the measured flow curve within the speed range of the RPT blower's fan curve.

[0363] Can be combined Figure 10A - Figure 10B Consider similar assessments using RPT during use (with a simulated respirator). Figure 10A and 10B In this diagram, the airflow of the RPT device includes a breathing component (rather than a fan-shaped curve). The graph plots measured flow rates and estimated flow rates relative to the blower speed of the RPT device during breathing-related operations at different altitudes. Figure 10A The data shown is from the device operating at an altitude of 2000 meters. Figure 10B Data from the device operating at an altitude of 3000 meters is shown. As illustrated, when the RPT's blower adjusts in response to the simulated user's breathing effort, the estimated flow curve remains very close to the measured flow rate.

[0364] 5.9 Glossary

[0365] To achieve the purposes of this technical disclosure, one or more of the following definitions may be applied in certain forms of this technology. Alternative definitions may be applied in other forms of this technology.

[0366] 5.9.1 Overview

[0367] Air: In some forms of this technology, air may be considered to mean atmospheric air, and in other forms of this technology, air may be considered to mean some other combination of breathable gases, such as oxygen-rich atmospheric air.

[0368] Environment: In some forms of this technology, the term “environment” refers to (i) the exterior of the treatment system or patient, and (ii) the exterior of the pneumatic path directly surrounding the treatment system or patient or RPT device.

[0369] For example, the ambient humidity relative to the humidifier can be the humidity of the air directly surrounding the humidifier, such as the humidity inside the patient's sleeping room. This ambient humidity can differ from the humidity outside the patient's sleeping room.

[0370] In another example, environmental stress can be stress that is directly around the body or outside the body.

[0371] In some forms, ambient (e.g., acoustic) noise can be considered as the background noise level in the patient's room, excluding noise generated by, for example, the RPT device or from the mask or patient interface. Ambient noise can be generated by sound sources outside the room.

[0372] Respiratory pressure therapy (RPT): Applying an air supply to the airway inlet at a treatment pressure that is normally positive relative to the atmosphere.

[0373] Continuous positive airway pressure (CPAP) therapy: respiratory pressure therapy in which the treatment pressure remains substantially constant throughout the patient's respiratory cycle. In some forms, the pressure at the airway inlet will be slightly higher during expiration and slightly lower during inspiration. In some forms, the pressure will vary between different respiratory cycles, for example, increasing in response to an indication of partial upper airway obstruction and decreasing in response to the absence of an indication of partial upper airway obstruction.

[0374] Patient: A person, whether or not they have a respiratory disorder.

[0375] Automated positive airway pressure (APAP) therapy: CPAP therapy in which the treatment pressure is automatically adjustable, for example, from one breath to another, between minimum and maximum, depending on the presence or absence of an SDB event indication.

[0376] 5.9.2 Regarding the respiratory cycle

[0377] Apnea: According to some definitions, apnea is said to have occurred when airflow drops below a predetermined threshold for a duration of, for example, 10 seconds. Closed apnea is considered to have occurred when some obstruction of the airway prevents airflow despite the patient's efforts. Open apnea is said to have occurred when apnea is detected even though the airway is open; this apnea is due to a reduction or absence of respiratory effort (patent). Mixed apnea occurs when a reduction or absence of respiratory effort coincides with an obstructed airway.

[0378] Respiratory rate: The rate at which a patient breathes spontaneously, usually measured in breaths per minute.

[0379] Work cycle or inspiratory fraction: the ratio of inhalation time Ti to total respiratory time Ttot.

[0380] Effort (breathing): Breathing effort will be referred to as the work done by a person who is trying to breathe spontaneously.

[0381] The expiratory phase of the respiratory cycle: the time period from the start of expiratory flow to the start of inspiratory flow.

[0382] Flow restriction: Flow restriction is considered a condition in a patient's breathing where increased effort does not result in a corresponding increase in flow. Flow restriction occurring during the inspiratory portion of the respiratory cycle can be described as inspiratory flow restriction. Flow restriction occurring during the expiratory portion of the respiratory cycle can be described as expiratory flow restriction.

[0383] Flow-restricted inhalation waveform types:

[0384] (i) (classical) flattened: has an ascending section, followed by a relatively flat section, followed by a descending section.

[0385] (ii) M-shape: has two local peaks, one in the early part and one in the late part, and a relatively flat part between the two peaks.

[0386] (iii) Chair-shaped: has a single local peak at the front, followed by a relatively flat section.

[0387] (iv) Inverted chair type: It has a relatively flat section followed by a single local peak, with the peak located at the rear.

[0388] Insufficient breathing: Reduced flow, but not cessation of flow. In one form, insufficient breathing can be considered to occur when the flow rate remains below a threshold for a sustained period. Central insufficiency is considered to occur when insufficient breathing is detected due to reduced respiratory effort.

[0389] Hyperventilation: Increased flow to a level higher than normal.

[0390] Inadequate ventilation: When the amount of gas exchanged within a certain time range is less than the patient's current needs, inadequate ventilation is said to occur.

[0391] Hyperventilation: Hyperventilation is defined as the amount of gas exchanged over a given timescale that exceeds the patient’s current requirements.

[0392] The inspiratory portion of the respiratory cycle: The time period from the start of inspiratory flow rate to the start of expiratory flow rate is considered the inspiratory portion of the respiratory cycle.

[0393] Airway patency: The degree to which the airway is open, or the extent to which the airway is open. The patient's airway is open. Airway patency can be quantified, for example, a value of one (1) indicates that the airway is open, while a value of zero (0) indicates that the airway is closed (obstructed).

[0394] Positive end-expiratory pressure (PEEP): The pressure above the atmosphere in the lungs at the end of expiration.

[0395] Peak flow (Qpeak): The maximum flow rate during the inspiratory portion of the respiratory flow waveform.

[0396] Respiratory flow rate, air flow rate, patient air flow rate, respiratory air flow rate (Qr): These synonyms can be understood as the RPT device's estimate of respiratory air flow rate, as opposed to "true respiratory flow" or "true respiratory airflow," which is the actual respiratory air flow rate experienced by the patient, usually expressed in liters per minute.

[0397] Tidal volume (Vt): The amount of air inhaled or exhaled with each breath during normal breathing without additional effort. This amount can be more specifically defined as inspiratory tidal volume (Vi) or expiratory tidal volume (Ve).

[0398] Inspiratory time (Ti): The duration of the inspiratory portion of the respiratory flow waveform.

[0399] Expiratory time (Te): The duration of the expiratory portion of the respiratory flow waveform.

[0400] Total (breathing) time (Ttot): The total duration between the start of the inspiratory portion of one respiratory flow waveform and the start of the inspiratory portion of the next respiratory flow waveform.

[0401] Typical recent ventilation: the ventilation values ​​that tend to cluster on a predetermined time scale, i.e., a measure of the clustering tendency of recent ventilation values.

[0402] Upper airway obstruction (UAO): This includes partial and complete upper airway obstruction. This may be associated with a state of flow restriction, where flow levels increase only slightly, or may even decrease with an increase in the pressure gradient across the upper airway (Starling resistance behavior).

[0403] Tidal volume (ventilation): Measures the total amount of gas exchanged by a patient's respiratory system. A tidal volume measurement can include one or both of inspiratory and expiratory flow rates (per unit of time). When expressed as volume per minute, this quantity is often referred to as "minute ventilation." Minute ventilation is sometimes simply expressed as volume and understood as volume per minute.

[0404] 5.9.3 RPT Device Parameters

[0405] Flow rate: The volume (or mass) of air delivered per unit time. While flow rate and ventilation have the same dimension of volume or mass per unit time, flow rate is measured over a shorter time period. In some cases, a reference to flow rate will be a scalar, i.e., a quantity that has only magnitude. In other cases, a reference to flow rate will be a vector, i.e., a quantity that has both magnitude and direction. In the case of quantities referred to as signed quantities, the inspiratory portion of a patient's respiratory cycle can be nominally positive, and therefore the expiratory portion of a patient's respiratory cycle can be negative. Flow rate can be represented by the symbol Q. 'Flow rate' is sometimes shortened to 'flow rate' or 'airflow'. Total flow rate (Qt) is the flow rate of air leaving the RPT device. Vent flow rate Qv is the flow rate of air leaving the vent to allow exhaled gas to escape. Leakage flow rate Ql is the leakage flow rate from the patient interface system. Respiratory flow rate (Qr) is the flow rate of air received into the patient's respiratory system.

[0406] Leakage: The term "leakage" refers to an unwanted flow of air. In one example, a leak could occur due to an incomplete seal between the mask and the patient's face. In another example, a leak could occur in a bend in the conduit leading to the surrounding environment.

[0407] Pressure: Force per unit area. Pressure can be measured in units, including cmH2O (cm⁻² water column), gf / cm², and hectopascals (hPa). 1 cmH2O equals 1 g⁻¹ / cm². 2 The pressure is approximately 0.98 hectopascals. In this instruction manual, unless otherwise stated, pressure is given in cmH2O. Pressure at the patient interface is given by the symbol Pm, while treatment pressure is represented by the symbol Pt, which indicates the target value achieved at the current moment by the mask pressure Pm.

[0408] 5.9.4 Ventilator Terminology

[0409] Standby rate: A parameter of the ventilator that determines the minimum respiratory rate (usually measured in breaths per minute) that the ventilator will deliver to the patient if not triggered by spontaneous breathing effort.

[0410] Cycle: The termination of the inspiratory phase of a ventilator. When a ventilator delivers breaths to a spontaneously breathing patient, the ventilator cycle is considered to end at the end of the inspiratory portion of the respiratory cycle.

[0411] Positive Expiratory Airway Pressure (EPAP): The base pressure to which the pressure changes within the respiratory tract are added to produce the desired mask pressure that the ventilator will attempt to achieve at a given time.

[0412] End-expiratory pressure (EEP) is the desired mask pressure that a ventilator attempts to achieve at the end of the expiratory phase of breathing. If the pressure waveform template Π(Φ) is zero at end-expiratory, i.e., Π(Φ) = 0, then EEP equals EPAP.

[0413] Inspiratory Positive Airway Pressure (IPAP): Inspiratory Positive Airway Pressure (IPAP): The maximum desired mask pressure that the ventilator attempts to achieve during the inspiratory phase of breathing.

[0414] Pressure support: A number indicating the increase in pressure during inspiration that exceeds the pressure during expiration, and generally refers to the pressure difference between the maximum pressure during inspiration and the baseline pressure (e.g., PS = IPAP - EPAP). In some cases, pressure support refers to the difference the ventilator is designed to achieve, rather than the difference it actually achieves.

[0415] Servo ventilator: A ventilator that measures a patient's ventilation volume, has a target ventilation volume, and adjusts the level of pressure support to enable the patient to achieve the target ventilation volume.

[0416] Spontaneous / Timed (S / T): A mode of operation for a ventilator or other device that attempts to detect the onset of spontaneous breathing in a patient. However, if the device fails to detect breathing within a predetermined time period, it will automatically initiate the delivery of breaths.

[0417] Swing difference: an equivalent term for pressure support.

[0418] Triggered: When a ventilator delivers breathing air to a patient who is breathing spontaneously, it is considered to be triggered by the patient's effort at the beginning of the breathing portion of the respiratory cycle.

[0419] Ventilator: A mechanical device that provides pressure support to a patient to perform some or all of the breathing work.

[0420] 5.9.5 Anatomical Structure of the Respiratory System

[0421] Diaphragm: A muscular plate that extends across the base of the ribcage. The diaphragm separates the thoracic cavity, which includes the heart, lungs, and ribs, from the abdominal cavity. As the diaphragm contracts, the volume of the thoracic cavity increases and air is drawn into the lungs.

[0422] The larynx: The larynx or larynx contains the vocal cords and connects the lower part of the pharynx (hypopharynx) to the trachea.

[0423] Lungs: The human respiratory organs. The conduction area of ​​the lungs includes the trachea, bronchi, bronchioles, and terminal bronchioles. The respiratory area includes the respiratory bronchioles, alveolar ducts, and alveoli.

[0424] Nasal cavity: The nasal cavity (or nasal socket) is a large, air-filled space located above and behind the nose in the middle of the face. The nasal cavity is divided into two parts by a vertical wing called the nasal septum. On the sides of the nasal cavity are three horizontal branches called nasal conchae (singular: "nasal conchae"). The front of the nasal cavity is the nasal part, while the back connects to the nasopharynx via the internal nasal openings.

[0425] Pharynx: The pharynx located below the nasal cavity and above the esophagus and larynx. The pharynx is conventionally divided into three parts: the nasopharynx (hyperpharynx) (the nasal part of the pharynx), the oropharynx (middle pharynx) (the oral part of the larynx), and the laryngopharynx (hypopharynx).

[0426] 5.10 Other Remarks

[0427] This patent document contains a portion of copyrighted material. The copyright holder does not object to the reproduction of these patent documents or patent disclosures by any person in the form they appear in the patent office documents or records, but otherwise reserves all copyright rights.

[0428] Unless explicitly stated in the context and a numerical range is provided, it should be understood that every intermediate value between the upper and lower limits of the range, up to one-tenth of the lower limit unit, and any other value or intermediate value within the range are broadly included within this technique. The upper and lower limits of these intermediate ranges may be included independently within the intermediate range and within the scope of this technique, but are subject to any explicitly excluded boundaries within the range. Where the range includes one or both of the extreme values, this technique also includes ranges that exclude any or both of those included extreme values.

[0429] Furthermore, in cases where one or more values ​​described herein are implemented as part of this technique, it should be understood that such values ​​may be approximate unless otherwise stated, and the extent to which such values ​​may be used in practical technical implementations is permitted or required for any appropriate number of digits.

[0430] 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 invention pertains. While any methods and materials similar to or equivalent to those described herein may be used in the practice or testing of the techniques of this invention, a limited number of exemplary methods and materials are described herein.

[0431] When a particular material is identified for use in a component, a readily available alternative material with similar properties is used as its substitute. Furthermore, unless otherwise stated, any and all components described herein are to be understood as being capable of being manufactured and therefore can be manufactured together or separately.

[0432] It must be noted that, unless the context clearly specifies otherwise, as used herein and in the appended claims, the singular forms “a,” “an,” and “the” include their plural equivalents.

[0433] All publications mentioned herein are incorporated herein in their entirety by reference to disclose and describe the methods and / or materials that are the subject of those publications. The publications discussed herein provide only disclosures prior to the filing date of this application. This document should not be construed as an admission by prior invention that the present invention was not authorized prior to such publications. Furthermore, the publication dates provided may differ from the actual publication dates, and publication dates may require independent verification.

[0434] The terms “comprising” and “including” should be interpreted as meaning that an element, component, or step referenced in a non-exclusive manner may be presented together, used together, or combined with other elements, components, or steps not explicitly referenced.

[0435] The headings used in the detailed description are for the convenience of the reader only and should not be used to limit the subject matter found in this disclosure or throughout the claims. The headings should not be used to interpret the scope or limitation of the claims.

[0436] Although specific implementations have been described herein, it should be understood that these implementations are merely illustrative of the principles and applications of the technology. In some examples, proper nouns, terms, and symbols may imply specific details not required for practicing the techniques of this invention. For example, although the terms "first" and "second" may be used, they are not intended to indicate any order unless otherwise specified, but rather to distinguish different elements. Furthermore, although process steps in a method may be described or illustrated in a certain order, this order is not necessary. Those skilled in the art will recognize that this order can be modified, and / or aspects of the order may be performed simultaneously or even concurrently.

[0437] Therefore, it should be understood that numerous modifications can be made to this exemplary implementation, and that other arrangements can be designed without departing from the spirit and scope of this technology.

[0438] 5.11 Reference Number List

[0439] Patient 1000

[0440] Patient Interface 3000

[0441] Non-invasive patient interface 3000

[0442] Sealing Formation Structure 3100

[0443] 3200 air chamber

[0444] Structure 3300

[0445] Vent 3400

[0446] Connection port 3600

[0447] Forehead support 3700

[0448] RPT device 4000

[0449] Outer casing 4010

[0450] Upper part 4012

[0451] Part 4014

[0452] Panel 4015

[0453] Chassis 4016

[0454] 4018 Handle

[0455] Pneumatic block 4020

[0456] Pneumatic component 4100

[0457] Air filter 4110

[0458] Inlet air filter 4112

[0459] 4114 Outlet air filter

[0460] Inlet silencer 4122

[0461] Export silencer 4124

[0462] Pressure generator 4140

[0463] Controllable blower 4142

[0464] Motor 4144

[0465] Air circuit 4170

[0466] Supplemental oxygen 4180

[0467] Electrical Components 4200

[0468] Printed circuit board assembly 4202

[0469] Power supply 4210

[0470] Input device 4220

[0471] Central controller 4230

[0472] Clock 4232

[0473] Treatment device controller 4240

[0474] Protection circuit 4250

[0475] 4260 memory

[0476] Converter 4270

[0477] Pressure sensor 4272

[0478] Flow sensor 4274

[0479] Gas temperature sensor 4275

[0480] Motor speed converter 4276

[0481] Atmospheric pressure sensor 4277

[0482] Ambient relative humidity sensor 4279

[0483] Data communication interface 4280

[0484] Remote external communication network 4282

[0485] Local external communication network 4284

[0486] Remote external device 4286

[0487] Local external device 4288

[0488] Output device 4290

[0489] Display driver 4292

[0490] Monitor 4294

[0491] Algorithm 4300

[0492] Preprocessing module 4310

[0493] Pressure compensation algorithm 4312

[0494] Ventilation flow rate estimated at 4314

[0495] Leakage flow estimation algorithm 4316

[0496] Flow signal estimation 4317

[0497] Respiratory flow estimation algorithm 4318

[0498] Healing Engine Module 4320

[0499] Phase determination algorithm 4321

[0500] Waveform Determination Algorithm 4322

[0501] Ventilation determination algorithm 4323

[0502] Inspiratory flow restriction test 4324

[0503] Sleep apnea detection algorithm 4325

[0504] M-shape detection algorithm 4326

[0505] Algorithm 4327 for determining airway patency

[0506] Typical recent ventilation volume determined to be 4328

[0507] Treatment parameter determination algorithm 4329

[0508] Treatment control module 4330

[0509] Humidifier 5000

[0510] Humidifier inlet 5002

[0511] Humidifier outlet 5004

[0512] Humidifier base 5006

[0513] Humidifier storage unit 5110

[0514] Humidifier reservoir base 5130

[0515] Heating element 5240

[0516] Humidifier controller 5250

[0517] Estimated processing 7002

[0518] Flow estimation unit 7004

[0519] Flow estimation signal 7008

[0520] Input signal 7010

[0521] Pressure 7012

[0522] Motor speed 7014

[0523] Atmospheric pressure 7016

[0524] Gas temperature 7018

[0525] Ambient relative humidity 70-20

[0526] Motor parameters 7021

[0527] Oxygen sensor signal 7023

[0528] Steps or processes 8002-34

Claims

1. A computer-readable storage medium storing processor-executable instructions thereon, the processor-executable instructions, when executed by a processor of a controller of a blower operated by a motor in a respiratory therapy device, causing the processor to generate an estimate of the flow rate of a breathable gas associated with the respiratory therapy device, the processor-executable instructions comprising instructions for: Receive an electronic signal from the pressure sensor representing a measurement of the pressure of the breathable gas; Receive an electronic signal from the speed sensor representing a speed measurement of the motor; Calculate the entrained air density function; and A flow estimation function is used to generate a signal representing an estimate of the flow rate of the breathable gas. The flow estimation function may include (a) a signal representing the pressure measurement, (b) a signal representing the motor speed measurement, and (c) a function incorporating the air density function. in, The entrained air density function includes functions of atmospheric pressure, temperature, and relative humidity. The functions of the atmospheric pressure value, the temperature value, and the relative humidity value include a saturated vapor pressure function based on temperature.

2. The computer-readable storage medium according to claim 1, wherein, The entrained air density function includes an air density value and an air density reference value.

3. The computer-readable storage medium according to claim 2, wherein, The entrained air density function includes a first ratio of the air density value to the air density reference value.

4. The computer-readable storage medium according to claim 3, wherein, The entrained air density function includes a second ratio of the air density value to the air density reference value.

5. The computer-readable storage medium according to any one of claims 1 to 4, wherein, To generate a signal representing an estimate of the flow rate, the instruction further includes instructions for determining an estimate of the flow rate of the breathable gas by calculating motor power, wherein the determined estimate of the flow rate of the breathable gas is based on the motor power.

6. The computer-readable storage medium according to any one of claims 1 to 4, wherein, It also includes evaluating signals from an oxygen sensor to calculate the entrained air density function.

7. The computer-readable storage medium according to any one of claims 1 to 4, further comprising instructions for: An electronic signal representing a measurement of the atmospheric pressure of the breathable gas is received from an atmospheric pressure sensor, wherein, The atmospheric pressure value is a measurement of the atmospheric pressure of the breathable gas; Receive an electronic signal from a gas temperature sensor representing a measured value of the temperature of the breathable gas, wherein the temperature value is the measured value of the temperature of the breathable gas; and An electronic signal representing a measurement of the ambient relative humidity of a breathable gas is received from an ambient relative humidity sensor, wherein the relative humidity value is the measurement of the ambient relative humidity of the breathable gas.

8. The computer-readable storage medium according to any one of claims 1 to 4, wherein, The saturated vapor pressure function based on temperature is defined as follows: Among them, Temp local_DegC It is a temperature value.

9. The computer-readable storage medium according to any one of claims 1 to 4, wherein, The functions of the atmospheric pressure value, the temperature value, and the relative humidity value include vapor pressure functions based on temperature and relative humidity.

10. The computer-readable storage medium according to claim 8, wherein, The vapor pressure function based on temperature and relative humidity is defined by multiplying (a) the result of the saturated vapor pressure function based on temperature by (b) the relative humidity value, as follows: RH local *Psv(Temp local_DegC ) Among them, RH local It is the relative humidity value, and Among them, Psv(Temp local_DegC ) is a saturated vapor pressure function based on temperature.

11. The computer-readable storage medium according to claim 10, wherein, The function of the atmospheric pressure value, the temperature value, and the relative humidity value is defined as follows: in: P0 = 103 hectoPascals; T0 = ​​15 degrees Celsius or 288.15 Kelvin; P atm_local This is the atmospheric pressure value; Pv(Temp local_DegC ,RH local It is a vapor pressure function based on temperature and relative humidity; and Temp local_DegK It is a temperature value.

12. The computer-readable storage medium according to any one of claims 1 to 4, wherein, The flow estimation function includes a set of frequency functions.

13. The computer-readable storage medium according to claim 12, wherein, The set of frequency functions includes a first rotational frequency function, which is a function of the motor speed measurement and the entrained air density function.

14. The computer-readable storage medium according to claim 13, wherein, The set of frequency functions includes a second rotational frequency function, which is a function of the measured speed of the motor.

15. The computer-readable storage medium according to claim 14, wherein, The set of frequency functions includes a third rotational frequency function, which is a function of the motor speed measurement and the entrained air density function.

16. The computer-readable storage medium according to claim 15, wherein, The first rotational frequency function is defined as follows: in: RPM is a measurement of motor speed; It is a function of entrained air density; and C1 and C2 are constants derived empirically.

17. The computer-readable storage medium according to any one of claims 14 to 16, wherein, The second rotational frequency function is defined by the following terms: -C3*RPM 2 -C4*RPM-C5 And among them: RPM is a measurement of motor speed; and C3, C4, and C5 are constants derived empirically.

18. The computer-readable storage medium according to claim 15, wherein, The third rotational frequency function is defined by the following terms: And among them: RPM is a measurement of motor speed; It is a function of entrained air density; and C6, C7, and C8 are constants derived empirically.

19. The computer-readable storage medium according to claim 18, wherein, The flow estimation function is defined as follows: in: A is the first rotational frequency function; B is the second rotational frequency function; C is the third rotational frequency function; and Pres_meas is a measurement of the pressure of the breathable gas from a pressure sensor.

20. The computer-readable storage medium according to any one of claims 1 to 4, further comprising instructions for: Receive an electronic signal representing a measurement of the flow rate of the breathable gas from the flow sensor; Compare the electronic signal representing the measured flow rate of the breathable gas with the generated signal representing the estimated flow rate of the breathable gas; and Based on the comparison, an output indicator is generated representing an estimate of the accuracy of the flow sensor.

21. The computer-readable storage medium according to claim 20, wherein, It also includes instructions for modifying the control parameters of the blower used to operate the motor based on the output indicator.

22. The computer-readable storage medium of claim 20, wherein, It also includes instructions for modifying control parameters of the blower used to operate the motor, based on a generated signal representing an estimate of the flow rate of the breathable gas.

23. The computer-readable storage medium according to any one of claims 21 and 22, wherein, The control parameter is either the pressure setpoint or the flow setpoint.

24. A respiratory therapy device, comprising: A motor-operated blower is adapted to couple with and generate respiratory therapy via a patient breathing interface, the respiratory therapy comprising a flow of breathable gas through the patient breathing interface. A pressure sensor is configured to generate an electronic signal representing a pressure measurement of the breathable gas; A speed sensor is configured to generate an electronic signal representing a measured value of the speed of the motor; A controller, including one or more processors and coupled to a blower operating on the motor, the pressure sensor, and the speed sensor, is configured to: Receive an electronic signal representing a measure of the pressure of the breathable gas; Receive an electronic signal representing a speed measurement of the motor; Calculate the entrained air density function; and A flow estimation function is used to generate a signal representing an estimate of the flow rate of the breathable gas. The flow estimation function may include (a) a signal representing the pressure measurement, (b) a signal representing the motor speed measurement, and (c) a function incorporating the air density function. The entrained air density function includes functions of atmospheric pressure, temperature, and relative humidity. The functions of the atmospheric pressure value, the temperature value, and the relative humidity value include a saturated vapor pressure function based on temperature.

25. The respiratory therapy device according to claim 24, wherein, The entrained air density function includes an air density value and an air density reference value.

26. The respiratory therapy device according to claim 25, wherein, The entrained air density function includes a first ratio of the air density value to the air density reference value.

27. The respiratory therapy device according to claim 26, wherein, The entrained air density function includes a second ratio of the air density value to the air density reference value.

28. The respiratory therapy device according to any one of claims 24 to 27, wherein, To determine an estimate of the breathable gas flow rate, the controller is also configured to calculate motor power based on one or more sensor signals, wherein the determined estimate of the breathable gas flow rate is based on the motor power.

29. The respiratory therapy device according to any one of claims 24 to 27, wherein, The controller is also configured to evaluate the signal from the oxygen sensor to calculate the entrained air density function.

30. The respiratory therapy device according to claim 29, further comprising: An atmospheric pressure sensor is configured to generate an electronic signal representing a measurement of the atmospheric pressure of the breathable gas, wherein the atmospheric pressure value is a measurement of the atmospheric pressure of the breathable gas. A gas temperature sensor is configured to generate an electronic signal representing a measured value of the gas temperature of the breathable gas, wherein the gas temperature value is the measured value of the gas temperature of the breathable gas; and An ambient relative humidity sensor is an electronic signal representing a measurement of the ambient relative humidity of the breathable gas, wherein the relative humidity value is a measurement of the ambient relative humidity of the breathable gas. The controller is configured to receive: An electronic signal representing a measurement of atmospheric pressure; An electronic signal representing a measured value of gas temperature; and An electronic signal representing the measurement of ambient relative humidity.

31. The respiratory therapy device according to any one of claims 24 to 27, wherein, The saturated vapor pressure function based on temperature is defined as follows: And among them, Temp local_DegC It is a temperature value.

32. The respiratory therapy device according to any one of claims 24 to 27, wherein, The functions of the atmospheric pressure value, the temperature value, and the relative humidity value include vapor pressure functions based on temperature and relative humidity.

33. The respiratory therapy device according to any one of claims 24 to 27, wherein, The vapor pressure function based on temperature and relative humidity is defined by multiplying (a) the result of the saturated vapor pressure function based on temperature by (b) the relative humidity value, as follows: RH local *Psv(Temp local_DegC ) Among them, RH local It is the relative humidity value, and Among them, Psv(Temp local_DegC ) is a saturated vapor pressure function based on temperature.

34. The respiratory therapy device according to any one of claims 24 to 27, wherein, The function of the atmospheric pressure value, the temperature value, and the relative humidity value is defined as follows: in: P0 = 103 hectoPascals; T0 = ​​15 degrees Celsius or 288.15 Kelvin; P atm_local This is the atmospheric pressure value; Pv(Temp local_DegC ,RH local It is a vapor pressure function based on temperature and relative humidity; and Temp local_DegK It is a temperature value.

35. The respiratory therapy device according to any one of claims 24 to 27, wherein, The flow estimation function includes a set of frequency functions.

36. The respiratory therapy device according to claim 35, wherein, The set of frequency functions includes a first rotational frequency function, which is a function of the motor speed measurement and the entrained air density function.

37. The respiratory therapy device according to claim 36, wherein, The set of frequency functions includes a second rotational frequency function, which is a function of the measured speed of the motor.

38. The respiratory therapy device according to claim 37, wherein, The set of frequency functions includes a third rotational frequency function, which is a function of the motor speed measurement and the entrained air density function.

39. The respiratory therapy device according to claim 36, wherein, The first rotational frequency function is defined as follows: in: RPM is a measurement of motor speed; It is a function of entrained air density; and C1 and C2 are constants derived empirically.

40. The respiratory therapy device according to claim 37, wherein, The second rotational frequency function is defined by the following terms: -C3*RPM 2 -C4*RPM-C5 in: RPM is a measurement of motor speed; and C3, C4, and C5 are constants derived empirically.

41. The respiratory therapy device according to claim 38, wherein, The third rotational frequency function is defined by the following terms: in: RPM is a measurement of motor speed; It is a function of entrained air density; and C6, C7, and C8 are constants derived empirically.

42. The respiratory therapy device according to claim 41, wherein, The flow estimation function is defined as follows: in: A is the first rotational frequency function; B is the second rotational frequency function; C is the third rotational frequency function; and Pres_meas is a measurement of the pressure of the breathable gas from a pressure sensor.

43. The respiratory therapy device according to any one of claims 24 to 27, further comprising: A flow sensor is configured to generate an electronic signal representing a measurement of the flow rate of the breathable gas; The controller is further configured as follows: Receive an electronic signal representing a measurement of the flow rate of the breathable gas; Compare the electronic signal representing the measured flow rate of the breathable gas with the generated signal representing the estimated flow rate of the breathable gas; and Based on the comparison, an output indicator is generated representing an estimate of the accuracy of the flow sensor.

44. The respiratory therapy device according to claim 43, wherein, The controller can also modify the control parameters of the blower used to operate the motor based on the output indicator.

45. The respiratory therapy device according to claim 43, wherein, The controller is also configured to modify the control parameters of the blower used to operate the motor based on a generated signal representing an estimate of the flow rate of the breathable gas.

46. ​​The respiratory therapy device according to any one of claims 44 and 45, wherein, The control parameter is either the pressure setpoint or the flow setpoint.

47. The respiratory therapy device according to any one of claims 24 to 27, further comprising a processor-readable medium storing processor-executable instructions that, when executed by one or more processors of the controller of the blower operated by the motor, cause the one or more processors to generate an estimate of the flow rate of the breathable gas, wherein, The processor executable instructions include instructions for controlling operations according to any one of claims 1 to 23.

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