Real-time detection of periodic breathing

Abstract

A method for utilizing a device to detect periodic breathing of a patient. The method may include receiving a series of event intervals defined by detection of apnea or hypopnea events in the patient's breathing, and processing the event intervals at the end of the event intervals to determine a characteristic of the event intervals, such as any of the following: likely a periodic breathing cycle; likely not a periodic breathing cycle; and not informative. The method may further include determining whether to change a current periodic breathing state indicating whether a periodic breathing event is ongoing based on a history of event interval characteristics that are longer than a typical length of a periodic breathing cycle.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Australian Provisional Application No. 2014900435 filed on February 13, 2014, the entire disclosure of which is incorporated herein by reference.

[0003] STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0004] not applicable

[0005] Names of joint research and development participants

[0006] not applicable

[0007] Sequence Listing

[0008] not applicable Technical Field

[0009] The present invention relates to one or more of the diagnosis, treatment, prevention and improvement of respiratory disorders. Specifically, the present invention relates to medical devices and their use in the treatment and prevention of respiratory disorders. Background Art

[0010] Description of Related Technology

[0011] The human respiratory system facilitates gas exchange. The nose and mouth form the entrances to the patient's airway.

[0012] The airways consist of a series of branching tracheae that become narrower, shorter, and more numerous as they penetrate deeper into the lungs. The main function of the lungs is gas exchange, allowing oxygen to pass from the air into the venous blood and expel carbon dioxide. The trachea divides into the left and right main bronchi, which then divide into the terminal bronchioles. The bronchi form the conducting airways but do not participate in gas exchange. Further branches of the airways lead to the respiratory bronchioles and ultimately to the alveoli. The alveolar region of the lungs is where gas exchange occurs and is called the respiratory zone. See West, Essentials of Respiratory Physiology.

[0013] The presence of multiple respiratory disorders.

[0014] Obstructive Sleep Apnea (OSA) is a form of sleep-disordered breathing (SDB) characterized by obstruction or occlusion of the upper airway during sleep. This is caused by a combination of an abnormally small upper airway and the normal loss of muscle tone in the tongue, soft palate, and posterior pharyngeal wall area during sleep. This symptom causes affected patients to stop breathing for a period of time each night, usually lasting 30 to 120 seconds, sometimes 200 to 300 times. It often causes excessive daytime sleepiness and may cause cardiovascular disease and brain damage. Complications are a common disease, especially in middle-aged overweight men, but those affected may not notice that there is a problem. See U.S. Patent No. 4,944,310 (Sullivan).

[0015] Cheyne-Stokes Respiration (CSR) is a periodic breathing form caused by a disorder of the patient's respiratory controller, in which there is a rhythmic alternation of boom and bust ventilation during sleep, causing repeated hypoxia and reoxygenation of arterial blood. Due to repeated hypoxia, CRS is potentially harmful. In some patients, CRS is associated with repetitive sleep arousals, which can cause severe sleep disruption, increased sympathetic nervous system activity, and an increase in afterload. See U.S. Patent No. 6,532,959 (Berthon-Jones).

[0016] Obesity Hyperventilation Syndrome (OHS) is defined as the combination of severe obesity and chronic hypercapnia during wakefulness in the absence of other known causes of hypoventilation. Symptoms include dyspnea, morning headaches, and excessive daytime sleepiness.

[0017] Chronic obstructive pulmonary disease (COPD) is a group of lower airway diseases that share certain common features. These include increased resistance to air flow, a prolonged expiratory phase of breathing, and loss of normal lung elasticity. Examples of COPD are emphysema and chronic bronchitis. COPD is caused by chronic smoking (a major risk factor), occupational exposure, air pollution, and genetic factors. Symptoms include dyspnea on exertion, a chronic cough, and sputum production.

[0018] Neuromuscular disease (NMD) is a broad term encompassing many diseases and disorders that impair muscle function directly through intrinsic muscle pathology or indirectly through neuropathology. Some patients with NMD are characterized by progressive muscle damage that can lead to loss of mobility (requiring wheelchair use), difficulty swallowing, respiratory muscle weakness, and ultimately death from respiratory failure. Neuromuscular diseases can be divided into rapidly progressive and slowly progressive: (i) rapidly progressive disorders are characterized by muscle damage that worsens over months and leads to death within years (e.g., juvenile amyotrophic lateral sclerosis (ALS) and Duchenne muscular dystrophy (DMD)); and (ii) variable or slowly progressive disorders are characterized by muscle damage that worsens over years with only a slight reduction in life expectancy (e.g., limb-girdle, facioscapulobrachial, and myotonic dystrophy). Symptoms of respiratory failure in NMD include: increasing general weakness, difficulty swallowing, dyspnea during exercise and at rest, fatigue, drowsiness, morning headaches, difficulty concentrating, and mood changes.

[0019] Chest wall disorders are a group of thoracic deformities that result in inefficient coupling between the respiratory muscles and the thorax. Disorders are often characterized by restrictive defects and all have the potential for long-term hypercapnic respiratory failure. Scoliosis and / or kyphoscoliosis can cause severe respiratory failure. Symptoms of respiratory failure include dyspnea on exertion, peripheral edema, orthopnea, recurrent chest infections, morning headaches, fatigue, poor sleep quality, and loss of appetite.

[0020] In other aspects, healthy individuals can utilize the systems and devices to prevent the development of respiratory disorders.

[0021] treat

[0022] Nasal continuous positive airway pressure (CPAP) therapy has been used to treat obstructive sleep apnea (OSA). The hypothesis is that CPAP acts as an inflatable splint and prevents upper airway obstruction by pushing the soft palate and tongue toward and away from the posterior pharyngeal wall.

[0023] Non-invasive ventilation (NIV) provides ventilator support to patients through the upper airway to help them breathe deeply and / or maintain adequate oxygen levels. Ventilator support is provided by a nasal mask or nasal interface. NIV has been used to treat CSR, OHS, COPD, MD, and chest wall disorders.

[0024] Invasive ventilation (IV) provides ventilation support to patients who can no longer breathe effectively on their own and is delivered using a tracheostomy tube.

[0025] The ventilator also controls the time and pressure of the breaths pumped into the patient and monitors the patient's breathing. Methods for controlling and monitoring the patient generally include volume cycle methods and pressure cycle methods. Among others, the volume cycle method may include pressure-regulated volume control (PRVC), volumetric ventilation (VV) and volume-controlled continuous mandatory ventilation (VC-CMV) technology. Among others, the pressure cycle method may include assist control (AC), synchronized intermittent mandatory ventilation (SIMV), controlled mechanical ventilation (CMV), pressure support ventilation (PSV), continuous positive airway pressure (CPAP), or positive end-expiratory pressure (PEEP) technology.

[0026] system

[0027] One known product for treating sleep-disordered breathing is the S9 sleep therapy system manufactured by ResMed. TM Series of adult and pediatric ventilators) can provide invasive and non-invasive non-dependent ventilation support for a wide range of patients, used to treat a variety of conditions such as, but not limited to, NMD, OHS and COPD.

[0028] ResMed Elisée TM 150 ventilator and ResMed VS III TM Ventilators can provide invasive or non-invasive dependent ventilation support to adults or children for a variety of conditions. These ventilators utilize single-limb or dual-limb circuits to provide both volume and pressure ventilation modes.

[0029] Patient interface

[0030] The application of a positive pressure air supply to the patient's airway entrance is facilitated by the use of a patient interface (e.g., a nasal mask, a full-face mask, or nasal pillows). Numerous patient interface devices are known, but many are one or more of cumbersome, aesthetically unpleasing, ill-fitting, difficult to use, and uncomfortable, particularly when worn for extended periods or when the patient is unfamiliar with the system. A nasal mask designed solely for pilots or for administering anesthetics as part of personal protective equipment may be tolerable in its initial use, however, it may be uncomfortable to wear for extended periods of time, such as while sleeping or throughout the day.

[0031] A tracheostomy tube is another form of patient interface used for invasive ventilation.

[0032] PAP devices

[0033] Positive pressure air can be supplied to the patient's airway by a PAP device such as a motor-driven blower. The outlet of the blower is connected to the patient interface as described above via an elastic delivery tube.

[0034] A ventilator typically includes an airflow generator or blower, an inlet filter, a patient interface, an air delivery conduit connecting the airflow generator to the patient interface, various sensors, and a microprocessor-based controller. The patient interface may include a nasal mask or a tracheostomy tube as described above. The airflow generator may include a servo-controlled motor, a spiral housing, and an impeller forming the blower. In some cases, a brake on the motor may be implemented to more quickly reduce the speed of the blower to overcome the inertia of the motor and impeller. The brake may allow the blower to achieve a lower pressure condition more quickly and in time to synchronize with exhalation regardless of inertia. In some cases, the airflow generator may also include a valve that, as an alternative to motor speed control, can exhaust the generated air to the atmosphere, as a means for varying the pressure delivered to the patient. Among other things, sensors measure motor speed, mass flow rate, and outlet pressure, such as using a pressure transducer or the like. The device may optionally include a humidifier and / or heater element in the path of the air delivery circuit. The controller may include data storage capabilities, with or without integrated data retrieval and display functions.

[0035] Monitoring system

[0036] The clinical significance of CSR is significant, so knowing how much CSR is present during sleep is important. Specifically, knowing whether a patient receiving CPAP therapy exhibits CSR is useful because of the potential for improving treatment with adaptive servoventilator (ASV) devices. Alternatively, the patient can be further monitored to see if CSR persists or is the result of so-called CPAP-induced central sleep apnea (CSA).

[0037] Diagnosis of CSR typically involves performing a sleep study and analyzing the resulting polysomnographic ("PSG") data. In a complete diagnostic PSG study, numerous physiological parameters are monitored, which typically include nasal flow signals, respiratory effort measurements, pulse oximetry, sleep position, and may further include: electroencephalogram ("EEG"), electrocardiogram ("ECG"), electromyogram ("EMG"), and electrooculogram ("EOG"). Respiratory characteristics can be identified from the visual signatures of the aforementioned parameters, allowing clinicians to assess respiratory function during sleep and detect and measure any CSR events.

[0038] While clinician examination is the most comprehensive approach, it is a costly process and relies heavily on clinical experience and understanding. To effectively screen patients, a classifier-based approach has been developed that automates the scoring process by calculating the probability of a CSR occurring regularly based on nasal flow signals. This approach is disclosed in U.S. Patent Application No. 11 / 576,210 (U.S. Patent Application Publication No. 20080177195), filed on March 28, 2007, and published on June 29, 2006 as WO2006066337A1. The approach includes a flow-based classifier that calculates the probability of a CSR given a series of discrete flow values. The method described in WO2006066337A1 uses a multidimensional feature space and performs cluster analysis by grouping features into clusters using a discriminant function. This approach is computationally intensive and, therefore, is typically performed on a separate computing device from the treatment device using a batch of data recorded between complete treatment or monitoring sessions.

[0039] Another method, disclosed in PCT Patent Application No. PCT / AU2013 / 000063 and published as WO2013110136 on August 1, 2013, also operates based on data recorded during a complete monitoring or treatment session. The method of WO2013110136 partitions the flow data into intervals based on SDB events, such as apneas and hypopneas, and constructs a histogram of interval lengths to determine whether CSRs occurred during the treatment session. Shape features of the data are also extracted and used to mark intervals as containing CSRs. Furthermore, this method is best suited for "batch mode" analysis at the end of a treatment session.

[0040] A more rapid method of detecting CSR events is needed, preferably one that operates "on the fly" based on only the most recent data during a monitoring or treatment session, i.e., "real time" as opposed to "batch mode." This would allow immediate action to be taken in response to a CSR event, such as a change in treatment parameters or an alert to a clinician, even before the end of the session. Summary of the Invention

[0041] The present technology is directed to providing medical devices for diagnosing, alleviating, treating, or preventing breathing disorders that have improved one or more of comfort, cost, efficacy, ease of use, and manufacturability.

[0042] A first aspect of the present technology relates to a device for diagnosing, ameliorating, treating or preventing a respiratory disorder.

[0043] Another aspect of the present technology relates to methods for diagnosing, ameliorating, treating or preventing breathing disorders.

[0044] One form of the present technology includes a device that determines in "real time" whether to signal the onset or end of a periodic respiratory event (eg, Cheyne-Stokes respiration) based on analysis of SDB events (eg, apneas and hypopneas).

[0045] Another aspect of one form of the present technology is a method of analyzing SDB events (eg, apneas and hypopneas) to determine the start and end times at or shortly after the occurrence of periodic respiratory events.

[0046] According to a first aspect of the present technology, a method for detecting periodic breathing in a patient is provided, the method comprising: receiving, using a processor, a series of event intervals defined by apnea or hypopnea events detected in the patient's breathing; at the end of the event interval, processing the event interval to determine a characteristic of the event interval, wherein the characteristic of the event interval is one of the following: may be a periodic breathing cycle; may not be a periodic breathing cycle; and is not referenceable; based on a history of event interval characteristics that is longer than the typical length of a periodic breathing cycle, using the processor to determine whether to change a current periodic breathing state indicating whether a periodic breathing event is ongoing.

[0047] According to another aspect of the present technology, a device for detecting periodic breathing in a patient is provided, the device comprising: a sensor configured to provide a signal representing the patient's respiratory airflow; and a processor configured to perform a method comprising: receiving, using the processor, a series of event intervals defined by apnea or hypopnea events detected in the patient's breathing; at the end of the event interval, processing the event interval to determine a characteristic of the event interval, wherein the characteristic of the event interval is one of the following: may be a periodic breathing cycle; may not be a periodic breathing cycle; and is not referenceable; and based on a history of event interval characteristics that is longer than the typical length of a periodic breathing cycle, determining, using the processor, whether to change a current periodic breathing state indicating whether a periodic breathing event is ongoing.

[0048] According to another aspect of the present technology, a computer-readable storage medium storing program code instructions is provided, wherein the program code instructions are configured to cause a processor to perform a method comprising: receiving, using a processor, a series of event intervals defined by apnea or hypopnea events detected in a patient's breathing; at the end of the event interval, processing the event interval to determine a characteristic of the event interval, wherein the characteristic of the event interval is one of the following: may be a periodic breathing cycle; may not be a periodic breathing cycle; and is not referenceable; and based on a history of event interval characteristics that is longer than a typical length of a periodic breathing cycle, determining, using the processor, whether to change a current periodic breathing state indicating whether a periodic breathing event is ongoing.

[0049] Certain versions of the present technology may include a method, for example, utilizing one or more processors to detect periodic breathing in a patient. The method may include receiving, with a processor, a series (e.g., a data series) of event intervals defined by apnea or hypopnea events detected in the patient's breathing. The method may include processing, with a processor, the event interval at the end of the event interval to determine a characteristic of the event interval, wherein the characteristic of the event interval is one of: likely a periodic breathing cycle; likely not a periodic breathing cycle; and not instructive. The method may also include determining, with a processor, based on a history of event interval characteristics that are longer than a typical length of a periodic breathing cycle, whether to change a current periodic breathing state indicating whether a periodic breathing event is ongoing.

[0050] In some cases, the method may further include reporting parameters of the detected periodic respiratory events. The patient may be receiving treatment for a respiratory disorder such that the method may further include adjusting one or more parameters of the treatment in response to the detected periodic respiratory events. In some versions of the method, processing may depend on a sequence of respiratory ventilation measurements associated with the event interval. The respiratory ventilation measurement is the product of the current half-breath amplitude and the previous half-breath amplitude. The half-breath amplitude can be the tidal volume of half a breath. Optionally, processing may include determining that the event interval may not be a periodic respiratory cycle if the duration of the event interval is outside the range of a typical periodic respiratory cycle, or the respiratory ventilation measurement sequence contains less than the minimum number of non-zero measurements of respiratory ventilation. Optionally, processing may further include calculating a relative maximum phase feature from the respiratory ventilation measurement sequence.

[0051] The processing may further include, in the event that the event interval ends with a hypopnea event: constructing a template representing an expected sequence of respiratory ventilation measurements consistent with an event interval that results in periodic hypopnea; calculating a difference between the sequence of respiratory ventilation measurements and the template; and determining a characteristic of the event interval based on the relative maximum phase feature and the difference. In some cases, the determination may include: determining that the event interval is likely not a periodic breathing cycle if the relative maximum phase feature exceeds a first threshold; and determining that the event interval is likely a periodic breathing cycle if the difference is less than a second threshold and the duration of the event interval is greater than a third threshold. Optionally, in the event that the event interval ends with an apnea event, the processing may include: constructing a template representing an expected sequence of respiratory ventilation measurements consistent with an event interval that results in obstructive sleep apnea; constructing a template representing an expected sequence of respiratory ventilation measurements consistent with an event interval that results in periodic apnea; calculating a difference between the sequence of respiratory ventilation measurements and each template; calculating a periodic breathing similarity score from the differences; and determining a characteristic of the event interval based on the relative maximum phase feature and the periodic breathing similarity score.

[0052] In some cases, the determination may include: if the relative maximum phase feature exceeds a first threshold, determining that the event interval may not be a periodic breathing cycle; and if the periodic breathing similarity score is greater than a second threshold and the duration of the event interval is greater than a third threshold, determining that the event interval may be a periodic breathing cycle. In some cases, the determination may also include: calculating a count of event intervals that may be periodic breathing cycles in history, a count of event intervals that may not be periodic breathing cycles in history, and a total count of event intervals in history; if the count meets a start criterion, changing the periodic breathing state to true; and if the count meets an end criterion, changing the periodic breathing state to false. The determination may include: if the event interval ends due to a timeout, changing the periodic breathing state to false. Optionally, in some cases, the method may further include: for example, when changing the periodic breathing state to true, adjusting the start time of a periodic breathing event that has just begun. In some cases, the method may include: for example, when changing the periodic breathing state to false, adjusting the end time of a periodic breathing event that has just ended.

[0053] Some versions of the present technology may include a device for detecting periodic breathing in a patient. The device may include a sensor configured to provide a signal representing the patient's respiratory airflow. The device may include a processor configured to detect periodic breathing in the patient. The processor may be configured to receive a series of event intervals defined by apnea or hypopnea events detected in the patient's breathing using the signal from the sensor. The processor may be configured to process the event interval at the end of the event interval to determine a characteristic of the event interval, wherein the characteristic of the event interval is one of the following: may be a periodic breathing cycle; may not be a periodic breathing cycle; and is not informative. The processor may be configured to determine whether to change the current periodic breathing state indicating whether a periodic breathing event is ongoing based on a history of event interval characteristics that are longer than the typical length of a periodic breathing cycle.

[0054] In some cases, the device may further include a treatment device configured to provide treatment for a respiratory disorder to the patient, and, for example, the processor may be further configured to adjust one or more parameters of the treatment in response to the detected periodic respiratory events. Optionally, the device may include a data communication interface coupled to the processor, and the processor may be further configured to report the parameters of the detected periodic respiratory events to an external device via the data communication interface.

[0055] The apparatus may further comprise a processor configured to control any one or more features of the method described above or throughout this specification.

[0056] Some versions of the present technology may include a computer-readable storage medium having program code instructions stored thereon, the program code instructions being configured to cause a processor to perform a method for detecting periodic breathing in a patient. The method may include providing for receiving a series of event intervals defined by apnea or hypopnea events detected in the patient's breathing. The method may include, at the end of the event interval, processing the event interval to determine a characteristic of the event interval, wherein the characteristic of the event interval is one of: possibly a periodic breathing cycle; possibly not a periodic breathing cycle; and not instructive. The method may include determining whether to change a current periodic breathing state indicating whether a periodic breathing event is ongoing based on a history of event interval characteristics that are longer than a typical length of a periodic breathing cycle. Any one or more additional optional features of the method may include features of the method described previously or throughout this specification.

[0057] Of course, parts of the aspects may form sub-aspects of the present technology. In addition, various aspects in the sub-aspects and / or aspects may be combined in various ways and may also constitute additional aspects or sub-aspects of the present technology.

[0058] Other features of the present technology will be apparent from consideration of the information contained in the following detailed description, abstract, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] The present technology is illustrated by way of example and not limitation in the figures of the accompanying drawings in which like reference numerals refer to similar elements, including:

[0060] Treatment system

[0061] Figure 1 A system according to one form of the present technology is shown. A patient 1000 wearing a patient interface 3000 receives a supply of positive pressure air from a PAP device 4000. The air from the PAP device is humidified in a humidifier 5000 and delivered to the patient 1000 along an air circuit 4170. A bed partner 1100 is also shown.

[0062] respiratory system

[0063] Figure 2 An overview of the human respiratory system is shown, including the nasal and oral cavities, larynx, vocal cords, esophagus, trachea, bronchi, lungs, alveolar sacs, heart, and diaphragm.

[0064] Patient interface

[0065] Figure 3 A patient interface 3000 is shown in accordance with one form of the present technology.

[0066] PAP devices

[0067] Figure 4A A PAP device 4000 in accordance with one form of the present technology is shown.

[0068] Figure 4B A schematic diagram of the pneumatic circuit of a PAP device 4000 according to one form of the present technology is shown. The upstream and downstream directions are indicated.

[0069] Figure 4C A schematic diagram illustrating electrical components of a PAP device 4000 in accordance with an aspect of the present technology is shown.

[0070] Figure 4D A schematic diagram of an algorithm 4300 implemented in a PAP device 4000 is shown in accordance with aspects of the present technique.

[0071] Figure 4E This is an explanation of one aspect of the present technology. Figure 4D Flowchart of method 4500 performed by the treatment engine module 4320.

[0072] humidifier

[0073] Figure 5 A humidifier 5000 is shown in accordance with one aspect of the present technology.

[0074] Respiratory waveform

[0075] Figure 6A Figure 2 shows a typical breathing waveform pattern for a person sleeping. The horizontal axis is time, and the vertical axis is respiratory flow. Although the parameter values ​​can vary, a typical breath can have the following approximate values: tidal volume (Vt) 0.5 L; inhalation time (Ti) 1.6 s; peak inspiratory flow (Qpeak) 0.4 L / s; exhalation time (Te) 2.4 s; peak expiratory flow (Qpeak) -0.5 L / s. The total duration of the breath (Ttot) is approximately 4 s. A typical person breathes at a rate of about 15 breaths per minute (BPM), with a ventilation volume of about 7.5 liters / minute at the ventilator (Vent). A typical duty cycle (the ratio of Ti to Ttot) is about 40%.

[0076] Figure 6B Data from a patient during non-REM sleep breathing (approximately 34 breaths) over a typical approximately 90-second period is shown, which was treated with auto-PAP and a nasal mask pressure of approximately 11 cmH2O. The upper channel shows blood oxygen saturation (SpO2), with the saturation scaled vertically from 90 to 99%. The patient maintained approximately 95% saturation throughout the shown period. The second channel shows quantitative respiratory airflow, with the scaled vertically from -1 to +1 L / s, while inspiratory under positive pressure. Chest and abdominal movements are shown in the third and fourth channels.

[0077] Figure 6C A polysomnogram of a patient before treatment is shown. There are 11 signal channels from top to bottom, with a horizontal span of 6 minutes. The upper two channels are two electroencephalograms (EEGs) from different scalp locations. The periodic spikes of the second EEG represent cortical activation and related activity. The lower third channel is the submental electromyogram (EMG). Increased activity during the wake-up period represents the recovery of the genioglossus muscle. The fourth and fifth channels are electrooculograms (EOGs). The sixth channel is an electrocardiogram. The seventh channel shows pulse oximetry (SpO2) with repeated desaturations from about 90% to below 70%. The eighth channel is the respiratory airflow using a nasal cannula connected to a differential pressure transducer. Repetitive apneas of 25 to 35 seconds alternate with 10 to 15 second recovery breathing bursts, which are consistent with EEG arousal and increased EMG activity. The ninth channel shows movement of the chest, and the tenth channel shows movement of the abdomen. The abdomen shows a gradual increase in movement within the length of the apnea that leads to arousal. Because of the whole body movement during the recovery breathing enhancement, both become unbalanced during arousal. Therefore, the apnea is obstructive and the condition is severe. The lowest channel is posture, and in this example, it shows no change.

[0078] Figure 6D Flow data for a patient experiencing a series of total obstructive apneas is shown. The duration of the recording was approximately 160 seconds. The flow range was approximately +1 L / s to approximately -1.5 L / s. Each apnea lasted approximately 10 to 15 seconds.

[0079] Figure 6E Data from a patient with Cheyne-Stokes breathing is shown. There are three channels: oxygen saturation (SpO2), a signal indicating flow, and motion. The time span of the data is 6 minutes. The signal indicating flow was measured using a pressure sensor connected to a nasal cannula. The patient presented with approximately 22 seconds of apnea and approximately 38 seconds of augmented breathing. The higher frequency, low amplitude oscillations during the apnea were of cardiac origin.

[0080] Figure 6F Data from another example patient with tidal breathing is shown using the same Figure 6E The same three channels. The data spans 10 minutes. The patient presented with approximately 30 seconds of apnea and approximately 30 seconds of augmented breathing.

[0081] Monitoring system

[0082] Figure 7 Another form of monitoring system according to the present technology is shown. A patient 1000 is monitored by a nearby non-contact motion sensor 7000.

[0083] Figure 8Contains instructions for implementing the present technology in one form Figure 4D Flowchart of the method of the Cheyne-Stokes respiration detection algorithm.

[0084] Figure 9 In one form, the present technology can be used to implement Figure 8 Diagram of a hierarchical state machine of event handlers for a method.

[0085] Figure 10 Contains instructions for implementing the present technology in one form Figure 8 A flow chart of the method of the event interval processing steps of the method.

[0086] Figure 11 In one form of the present technology, instructions are included for use in implementing a method in which an event interval ends due to a hypopnea event. Figure 10 A flow chart of the method showing the characteristic determination steps of the method.

[0087] Figure 12 Contains instructions for implementing, in one form, the present technology when an event interval ends due to an apnea event. Figure 10 A flow chart of the method showing the characteristic determination steps of the method.

[0088] Figure 13 An example of the evolution of the contents of a ring buffer recording event interval statistics in an implementation using 38 storage bins in the ring buffer is described.

[0089] Figure 14 Contains instructions for implementing the present technology in one form Figure 8 A flow chart of the method of the CSR status determination steps of the method.

[0090] Figure 15A and Figure 15B Contains instructions for respiratory flow examples Figure 4D Graph of the operation of the CSR detection algorithm.

[0091] Figure 16 Contains instructions for Figure 15B Graph of the operation of the previous CSR detection algorithm for the same respiratory flow example. DETAILED DESCRIPTION

[0092] Before describing the present technology in further detail, it should be understood that the present technology is not limited to the specific embodiments described herein, which may vary. It should also be understood that the terminology used herein is for the purpose of describing the specific embodiments discussed herein only and is not intended to be limiting.

[0093] treat

[0094] In one form, the present technology comprises a method for treating a breathing disorder comprising the step of applying positive pressure to an airway entrance of a patient 1000 .

[0095] Treatment system

[0096] In one form, the present technology includes an apparatus for treating a respiratory disorder. The apparatus may include a PAP device 4000 for supplying pressurized breathing gas, such as air, to an airway entrance of a patient 1000 via a gas delivery tube leading to a patient interface 3000 .

[0097] Patient interface

[0098] A non-invasive patient interface 3000 according to one aspect of the present technology includes the following functional aspects: a seal-forming structure 3100, a plenum chamber 3200, a positioning and stabilizing structure 3300, a ventilation port 3400, a connection port 3600 for connecting to a form of 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, one physical component may provide one or more functional aspects. In use, the seal-forming structure 3100 is arranged to surround the patient's airway entrance to facilitate the supply of positive pressure air to the airway.

[0099] PAP devices

[0100] A preferred PAP device 4000 according to one aspect of the present technology includes a mechanical and pneumatic assembly 4100 and an electrical assembly 4200, and is programmed to execute one or more algorithms 4300. The PAP device 4000 preferably has an outer housing 4010, which is preferably formed in two parts: an upper portion 4012 of the outer housing 4010 and a lower portion 4014 of the outer housing 4010. In an alternative form, the outer housing 4010 may include one or more panels 4015. Preferably, the PAP device 4000 includes a chassis 4016 that supports one or more internal components of the PAP device 4000. In one form, a pneumatic block 4020 is supported by or formed as part of the chassis 4016. The PAP device 4000 may include a handle 4018.

[0101] The pneumatic path of the PAP device 4000 preferably includes an inlet air filter 4112, an inlet muffler 4122, a controllable pressure device 4140 capable of supplying positive pressure air (preferably a blower 4142), and an outlet muffler 4124. One or more sensors or transducers 4270 are included within the pneumatic path.

[0102] The preferred pneumatic block 4020 includes a portion of the pneumatic path located within the outer housing 4010.

[0103] The PAP device 4000 preferably has a power supply 4210, one or more input devices 4220, a processor 4230, a therapy device controller 4240, a therapy device 4245, one or more protection circuits 4250, a memory 4260, a converter 4270, a data communication interface 4280, and one or more output devices 4290. The electrical components 4200 may be mounted on a single printed circuit board assembly (PCBA) 4202. In alternative forms, the PAP device 4000 may include more than one PCBA 4202.

[0104] PAP device mechanical and pneumatic components 4100

[0105] Air filter(s) 4110

[0106] A PAP device according to one form of the present technology may include an air filter 4110 or a plurality of air filters 4110 .

[0107] In one form, the inlet air filter 4112 is located at the beginning of the pneumatic path upstream of the pressure device 4140.

[0108] In one form, an outlet air filter 4114 (eg, an antimicrobial filter) is located between the outlet of the pneumatic block 4020 and the patient interface 3000 .

[0109] (Multiple) mufflers 4120

[0110] In one form of the present technology, an inlet muffler 4122 is located in the pneumatic path upstream of the pressure device 4140 .

[0111] In one form of the present technology, an outlet muffler 4124 is located within the pneumatic path between the pressure device 4140 and the patient interface 3000 .

[0112] Pressure Device 4140

[0113] In a preferred form of the present technology, the pressure device 4140 for generating a positive pressure air flow is a controllable blower 4142. For example, the blower may include a brushless direct current (DC) motor 4144 having one or more impellers housed in a spiral housing. Preferably, the blower may be capable of delivering an air supply (e.g., about 120 liters / minute) with a positive pressure ranging from about 4 cmH2O to about 20 cmH2O, or in other forms up to about 30 cmH2O.

[0114] The pressure device 4140 is under the control of the treatment device controller 4240.

[0115] (Multiple) Converters 4270

[0116] In one form of the present technology, one or more transducers 4270 are located upstream of the pressure device 4140. The one or more transducers 4270 are constructed and arranged to measure the property of the air at the point in the pneumatic path.

[0117] In one form of the present technology, one or more transducers 4270 are located downstream of the pressure device 4140 and upstream of the air circuit 4170. The one or more transducers 4270 are constructed and arranged to measure properties of the air at that point in the pneumatic path.

[0118] In one form of the present technology, one or more transducers 4270 are located proximate to the patient interface 3000 .

[0119] Anti-overflow valve 4160

[0120] In one form of the present technology, an anti-spill back valve is located between the humidifier 5000 and the pneumatic block 4020. The anti-spill back valve is constructed and arranged to reduce the risk of water flowing upstream from the humidifier 5000, for example, to the motor 4144.

[0121] Air circuit 4170

[0122] The air circuit 4170 in accordance with one aspect of the present technology is constructed and arranged to allow air or breathable gas to flow between the pneumatic block 4020 and the patient interface 3000 .

[0123] Supplemental oxygen 4180

[0124] In one form of the present technology, supplemental oxygen 4180 is delivered to a point in the pneumatic pathway.

[0125] In one form of the present technology, supplemental oxygen 4180 is delivered upstream of the pneumatic block 4020 .

[0126] In one form of the present technology, supplemental oxygen 4180 is delivered to the air circuit 4170 .

[0127] In one form of the present technology, supplemental oxygen 4180 is delivered to the patient interface 3000 .

[0128] PAP device electrical components 4200

[0129] Power Supply 4210

[0130] In one form of the present technology, the power supply 4210 is located inside the outer housing 4010 of the PAP device 4000. In another form of the present technology, the power supply 4210 is located outside the outer housing 4010 of the PAP device 4000.

[0131] In one form of the present technology, the power supply 4210 provides power only to the PAP device 4000. In another form of the present technology, the power supply 4210 provides power to both the PAP device 4000 and the humidifier 5000.

[0132] Input device 4220

[0133] In one form of the present technology, the PAP device 4000 includes one or more input devices 4220 in the form of buttons, switches, or dials to allow a person to interact with the device. The buttons, switches, or dials may be physical devices or software devices that can be used via a touch screen. In one form, the buttons, switches, or dials may be physically connected to the external housing 4010 or, in another form, may communicate wirelessly with a receiver that is electrically connected to the processor 4230.

[0134] In one form, input device 4220 may be constructed and arranged to allow a person to select a value and / or menu option.

[0135] Processor 4230

[0136] In one form of the present technology, processor 4230 is a processor suitable for controlling PAP device 4000, such as an x86 INTEL processor.

[0137] A processor 4230 suitable for controlling a PAP device 4000 according to another form of the present technology comprises a processor based on an ARM Cortex-M processor from ARM Holdings. For example, an STM32 series microcontroller from ST MICROELECTRONICS may be used.

[0138] Another processor 4230 suitable for controlling the PAP device 4000 according to another alternative form of the present technology comprises a component selected from a 32-bit RISC CPU based on the ARM9 series. For example, the STR9 series of microcontrollers from ST MICROELECTRONICS may be used.

[0139] In some alternative forms of the present technology, a 16-bit RISC CPU may be used as the processor 4230 of the PAP device 4000. For example, a processor from the MSP430 series of microcontrollers manufactured by TEXAS INSTRUMENTS may be used.

[0140] The processor 4230 is configured to receive input signal(s) from one or more converters 4270 and one or more input devices 4220 .

[0141] The processor 4230 is configured to provide output signal(s) to one or more of the output device 4290 , the therapy device controller 4240 , the data communication interface 4280 , and the humidifier controller 5250 .

[0142] In some forms of the present technology, processor 4230 or a plurality of such processors is configured to implement one or more of the methods described herein, such as one or more algorithms 4300, represented as computer programs stored in a non-transitory computer-readable storage medium (e.g., memory 4260). In some cases, as previously discussed, such a processor may be integrated with the PAP device 4000. However, in some forms of the present technology, the processor may be implemented separately from the flow generating components of the PAP device 4000, for example, to perform any of the methods described herein rather than directly controlling the delivery of respiratory therapy. For example, such a processor may perform any of the methods described herein to determine control settings for a ventilator or other respiratory-related event by analyzing stored data, such as from any of the sensors described herein.

[0143] The processor 4230 of the PAP device 4000 is programmed to execute one or more algorithms 4300 , preferably including a pre-processing module 4310 , a therapy engine module 4320 , a therapy control module 4330 , a reporting module 4335 , and a fault condition detection module 4340 .

[0144] Clock 4232

[0145] Preferably, the PAP device 4000 includes a clock 4232 connected to the processor 4230 .

[0146] Treatment device controller 4240

[0147] In one form of the present technology, the treatment device controller 4240 is a treatment control module 4330 that forms part of the algorithm 4300 executed by the processor 4230.

[0148] In another form of the present technology, the treatment device controller 4240 is a dedicated motor control integrated circuit. For example, in one form, the MC33035 brushless DC motor controller manufactured by ONSEMI is used.

[0149] Protection circuit 4250

[0150] Preferably, a PAP device 4000 in accordance with the present technology includes one or more protection circuits 4250 .

[0151] One form of protection circuit 4250 according to the present technology is an electrical protection circuit.

[0152] One form of protection circuit 4250 according to the present technology is a temperature or pressure safety circuit.

[0153] Memory 4260

[0154] According to one form of the present technology, PAP device 4000 includes memory 4260, preferably non-volatile memory. In some forms, memory 4260 may include battery-powered static RAM. In some forms, memory 4260 may include volatile RAM.

[0155] Preferably, the memory 4260 is located on the PCBA 4202. The memory 4260 may be in the form of an EEPROM or a NAND flash memory.

[0156] Additionally or alternatively, the PAP device 4000 includes memory 4260 in a removable form, such as a memory card manufactured according to the Secure Digital (SD) standard.

[0157] In one form of the present technology, the memory 4260 acts as a non-transitory computer-readable storage medium having stored thereon computer program instructions encoding one or more methods described herein (e.g., one or more algorithms 4300). The processor 4230 is configured to execute these instructions stored on the non-transitory computer-readable storage medium.

[0158] Converter 4270

[0159] The transducer may be located internally to the PAP device 4000 or externally to the PAP device 4000. An external transducer may be located on or form part of the air circuit 4170, such as at the patient interface 3000. The external transducer may be in the form of a non-contact sensor, such as a Doppler radar motion sensor that transmits or transfers data to the PAP device 4000.

[0160] Flow Converter 4274

[0161] A flow transducer 4274 according to the present technology may be based on a differential pressure transducer, such as the SDP600 series differential pressure transducers from SENSIRION. The differential pressure transducers are in fluid communication with the pneumatic circuit, with each pressure transducer connected to respective first and second points in the flow restriction element.

[0162] In one example, a signal representing the total flow Qt from the flow converter 4274 is received by the processor 4230 .

[0163] Pressure Converter 4272

[0164] A pressure transducer 4272 according to the present technology is positioned in fluid communication with the pneumatic path. An example of a suitable pressure transducer 4272 is the ASDX series of sensors from Honeywell. An alternative suitable pressure transducer is the NPA series of sensors from General Electric.

[0165] In use, the signal from the pressure transducer 4272 is received by the processor 4230. In one form, the signal from the pressure transducer 4272 is filtered before being received by the processor 4230.

[0166] Motor speed signal 4276

[0167] In one form of the present technology, a motor speed signal 4276 is generated. The motor speed signal 4276 is preferably provided by the treatment device controller 4240. The motor speed may, for example, be generated by a speed sensor, such as a Hall effect sensor.

[0168] Data Communication Interface 4280

[0169] In one preferred form of the present technology, a data communication interface 4280 is provided and connected to the processor 4230. Preferably, the data communication interface 4280 is connectable to a remote external communication network 4282. Preferably, the data communication interface 4280 is connectable to a local external communication network 4284. Preferably, the remote external communication network 4282 is connectable to a remote external device 4286. Preferably, the local external communication network 4284 is connectable to a local external device 4288.

[0170] In one form, the data communications interface 4280 is part of the processor 4230. In another form, the data communications interface 4280 is a separate integrated circuit from the processor 4230.

[0171] In one form, remote external communication network 4282 is the Internet. Data communication interface 4280 may use wired communication (eg, via Ethernet or fiber optics) or wireless protocols to connect to the Internet.

[0172] In one form, the local external communication network 4284 utilizes one or more communication standards, such as Bluetooth or consumer infrared protocols.

[0173] In one form, the remote external device 4286 is one or more computers, such as a networked computer cluster. 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 may be used by appropriately authorized personnel, such as a clinician.

[0174] Preferably, the local external device 4288 is a personal computer, a mobile phone, a tablet or a remote control device.

[0175] Output device 4290 including optional display and alarm

[0176] Output devices 4290 according to the present technology may take the form of one or more of visual, audio, and tactile units.The visual display may be a liquid crystal display (LCD) or a light emitting diode (LED) display.

[0177] Display Driver 4292

[0178] The display driver 4292 receives as input characters, symbols, or images intended for display on the display 4294 and converts them into commands that cause the display 4294 to display those characters, symbols, or images.

[0179] Display 4294

[0180] The display 4294 is configured to visually display characters, symbols, or images in response to commands received from the display driver 4292. For example, the display 4294 may be an eight-segment display, in which case the display driver 4292 converts each character or symbol (e.g., the number "0") into eight logic signals that indicate whether to activate the eight corresponding segments to display the particular character or symbol.

[0181] PAP Device Algorithm 4300

[0182] Preprocessing module 4310

[0183] A pre-processing module 4310 according to the present technology receives raw data as input from a transducer (e.g., a flow or pressure transducer) and preferably performs one or more processing steps to calculate one or more output values, which are used as input to another module (e.g., a treatment engine module 4320).

[0184] In one form of the present technology, the output values ​​include the interface or mask pressure Pm, the respiratory flow Qr, and the leakage flow Ql.

[0185] In various forms of the present technology, pre-processing module 4310 includes one or more of the following algorithms: pressure compensation 4312, ventilator flow 4314, leak flow 4316, respiratory flow 4318, and respiratory framer 4319.

[0186] Pressure Compensation 4312

[0187] In one form of the present technology, a pressure compensation algorithm 4312 receives as input a signal indicative of the pressure in the pneumatic path proximate the outlet of the pneumatic block 4020. The pressure compensation algorithm 4312 estimates the pressure drop in the air circuit 4170 and provides as output an estimated pressure Pm in the patient interface 3000.

[0188] Ventilation port flow rate 4314

[0189] In one form of the present technology, a vent flow estimation algorithm 4312 receives as input an estimated pressure Pm in the patient interface 3000 and estimates a vent air flow Qv from the vent 3400 in the patient interface 3000 .

[0190] Leakage flow 4316

[0191] In one form of the present technology, the leak flow algorithm 4316 receives the total flow Qt and the ventilator flow Qv as inputs and provides the leak flow Ql as output by averaging Qt-Qv over a sufficiently long period (e.g., approximately 10 seconds) including several respiratory cycles.

[0192] In one form, the leak flow algorithm 4316 receives as input the total flow Qt, the ventilator flow Qv, and the estimated pressure Pm in the patient interface 3000, and provides as output a leak flow Ql by calculating a leak conductance and determining the leak flow Ql (which is a function of the leak conductance) and the pressure Pm. Preferably, the leak conductance is calculated as the quotient of the low-pass filtered non-ventilator flow Qt-Qv and the low-pass filtered square root of the pressure Pm, where the low-pass filter time constant is large enough to cover several respiratory cycles, for example, about 10 seconds.

[0193] Respiratory flow 4318

[0194] In one form of the present technology, respiratory flow algorithm 4318 receives as inputs the total flow Qt, the ventilator flow Qv, and the leak flow Ql and estimates the patient's air respiratory flow Qr by subtracting the ventilator flow Qv and the leak flow Ql from the total flow Qt.

[0195] Breathing Framer 4319

[0196] In one form of the present technology, a breath framer 4319 receives as input the patient's air breath flow Qr and provides as output a series of "half-breath markers" that indicate the end of each half-breath (i.e., the end of the inspiratory portion and the end of the expiratory portion of each breath).

[0197] Breath framer 4319 also provides a series of measurements of each half-breath amplitude at the end of each half-breath. In one form of the present technology, breath framer 4319 calculates each half-breath amplitude as the tidal volume, i.e., the integral of the absolute value of the respiratory flow rate Qr over the interval between each consecutive pair of half-breath markers. In other forms, the half-breath amplitude is the peak flow rate, the average flow rate, the inspiration / expiration time, the respiratory rate, or some other half-breath amplitude measure of the absolute value of the respiratory flow rate Qr over the interval.

[0198] Treatment Engine Module 4320

[0199] In one form of the present technology, the therapy engine module 4320 receives as input one or more of the pressure Pm in the patient interface 3000 and the patient's air respiratory flow Qr and provides as output one or more therapy parameters.

[0200] In one form of the present technology, the therapy parameter is CPAP therapy pressure Pt.

[0201] In one form of the present technology, the therapy parameter is one or more of a pressure support level and a target ventilation volume.

[0202] Phase determination 4321

[0203] In one form of the present technology, a phase determination algorithm 4321 receives as input a signal indicative of respiratory flow Qr and provides as output the phase of the patient's 1000 respiratory cycle.

[0204] In one form, the phase output is a discrete variable having either an inspiratory or expiratory value.

[0205] In one form, the phase output is a discrete variable having values ​​of one of inspiration, mid-breath pause, and expiration.

[0206] In one form, the phase output is a continuous variable, for example varying from 0 to 1 or from 0 to 2π.

[0207] In one form, when the respiratory flow Qr has a positive value exceeding a positive threshold, the phase output is determined to have a discrete inspiratory value. In one form, when the respiratory flow Qr has a negative value (more negative than the negative threshold), the phase is determined to have a discrete expiratory value.

[0208] Ventilation judgment 4323

[0209] In one form of the present technology, a ventilation determination algorithm 4323 receives as input respiratory flow Qr and determines a measure indicative of patient ventilation Vent.

[0210] In one form, ventilation determination algorithm 4323 determines the current value of patient ventilation Vent as half the low pass filtered absolute value of respiratory flow Qr.

[0211] Waveform judgment 4322

[0212] In one form of the present technology, the control module 4330 controls the therapy device 4245 to provide positive airway pressure according to a predetermined pressure waveform as a function of phase. In one form, the waveform is maintained at a substantially constant level for all phase values. In one form, the waveform is a square wave having a higher level for some phase values ​​and a lower level for other phase values.

[0213] In one form of the present technology, a waveform determination algorithm 4322 receives as input a value indicative of current patient ventilation Vent and provides as output a pressure waveform as a function of phase.

[0214] Determination of Inspiratory Flow Limitation 4324

[0215] In one form of the present technology, a processor executes one or more algorithms 4324 for detecting inspiratory flow limitation.

[0216] In one form, algorithm 4324 receives as input the respiratory flow signal Qr and provides as output a measure of the extent to which the inspiratory portion of the breath exhibits inspiratory flow limitation.

[0217] In one form of the present technology, the inspiratory portion of each breath is identified by a zero crossing detector. A large number of evenly spaced points (e.g., 65 points) representing time points are interpolated by an interpolator along the inspiratory flow time curve for each breath. The curve described by these points is then calibrated by a scaler to have unit length (duration / period) and unit area to remove the effects of varying breathing rate and depth. The calibrated breaths are then compared using a comparator to a pre-stored template representing a normal, unobstructed breath, similar to Figure 6AThe inspiratory portion of the breath shown. Breaths that deviate from this sample by more than a specified threshold (typically 1 scale unit) at any time during a breath from this sample (e.g., breaths due to coughs, sighs, swallows, and burps, as determined by the test element) are rejected. For data that is not rejected, a moving average is calculated by processor 4230 for the first such calibration point of the aforementioned several inspiratory events. This is repeated for the same inspiratory event at the second such point, and so on. Thus, for example, 65 calibration data points are generated by processor 4230, and the calibration data points represent a moving average of the aforementioned several inspiratory events (e.g., three events). The moving average of the continuously updated values ​​of the (e.g., 65) points is hereinafter referred to as "proportional flow," which is denoted as Qs(t). Alternatively, a single inspiratory event may be used instead of a moving average.

[0218] From the proportional flow, two shape factors can be calculated that are relevant to determining partial blockage.

[0219] Shape Factor 1 is the ratio of the average of the middle (e.g., 32) proportional flow points to the average of all (e.g., 65) proportional flow points. When the ratio exceeds one, the breathing is considered normal. When the ratio is one or less, the breathing is considered obstructed. A ratio of approximately 1.17 is considered the threshold between partially obstructed and unobstructed breathing and is equivalent to the degree of obstruction that will allow for maintenance of adequate oxygenation in a typical user.

[0220] Shape Factor 2 is calculated as the RMS deviation of R from the unit ratio flow at the middle (e.g., 32) point. An RMS deviation of approximately 0.2 units is considered normal. An RMS deviation of zero is considered a fully flow-limited breath. The closer the RMS deviation is to zero, the more flow-limited the breath will be.

[0221] Form factors 1 and 2 may be used in place of or in combination. In other forms of the present technology, the number of sampling points, breaths, and intermediate points may be different than described above. Additionally, the thresholds may be other than those described.

[0222] Determination of respiratory arrest and hypopnea 4325

[0223] In one form of the present technology, processor 4230 executes one or more algorithms 4325 for determining the presence of apnea and / or hypopnea.

[0224] Preferably, the one or more algorithms 4325 receive as input the respiratory flow signal Qr and provide as output an event indicative of apnea or termination of hypopnea.

[0225] In one form, apnea is detected when a function of respiratory flow Qr falls below a flow threshold for a predetermined period of time. The function may determine peak flow, a relatively short-term average flow, or a flow value intermediate between the relatively short-term average flow and peak flow, such as RMS flow. The flow threshold may be a relatively long-term flow measurement.

[0226] In one form, hypopnea is detected when the function of respiratory flow Qr falls below a second flow threshold over a predetermined period of time. The function may determine peak flow, a relatively short-term average flow, or a flow intermediate between the relatively short-term average flow and peak flow, such as RMS flow. The second flow threshold may be a relatively long-term flow measurement. The second flow threshold is greater than a flow threshold used to detect apnea.

[0227] Snoring Determination 4326

[0228] In one form of the present technology, processor 4230 executes one or more snore algorithms 4326 for determining snoring.

[0229] In one form, the snore algorithm 4326 receives as input the respiratory flow signal Qr and provides as output a measure of the extent to which snoring is present.

[0230] Preferably, the algorithm 4326 includes a step of determining the flow signal strength in the range of 30 to 300 Hz. Further preferably, the algorithm 4326 includes a step of filtering the respiratory flow signal Qr to reduce background noise (eg, airflow sound from a blower in the system).

[0231] Determination of airway patency 4327

[0232] In one form of the present technology, the processor 4230 executes one or more algorithms 4327 for determining airway patency.

[0233] In one form, the airway patency algorithm 4327 receives the respiratory flow signal Qr as input and determines the signal power within a frequency range of about 0.75 Hz to about 3 Hz. The presence of a peak in this frequency range is considered to indicate airway patency. The absence of a peak is considered to indicate airway obstruction.

[0234] In one form, the peak found in the frequency range is the frequency of the small forced oscillation at the therapeutic pressure Pt. In one embodiment, the frequency of the forced oscillation is 2 Hz, with an amplitude of about 1 cmH20.

[0235] In one form, the airway general algorithm 4327 receives as input the respiratory flow signal Qr and determines whether a cardiac signal is present. The absence of a cardiac signal is considered indicative of airway obstruction.

[0236] Treatment parameter determination 4328

[0237] In one form of the present technology, the processor 4230 executes one or more algorithms 4328 for determining treatment parameters (e.g., target treatment pressure Pt). In one embodiment, the treatment parameter determination algorithm 4328 receives as input one or more of the following:

[0238] i. The measurement of the respiratory phase at the current time t Π(t) (can be discrete or continuous);

[0239] ii. Waveform function Φ(Π) (may be a square wave or other waveform), such as a phase function;

[0240] iii. Measurement of ventilation (Vent);

[0241] iv. Measurement of inspiratory flow limitation;

[0242] v. Measurement of the presence of apneas and / or hypopneas;

[0243] vi. measurement of the presence of snoring; and

[0244] vii. Measurement of airway patency.

[0245] In one form of the present technology, the treatment parameter determination algorithm 4328 calculates the amplitude A based on the integral governing equation:

[0246] A=G∫(Vent-Vtgt)dt (1),

[0247] Wherein, Vtgt is the target ventilation. In other forms, other control modes can be used to calculate the amplitude A, such as proportional, proportional derivative, proportional integral derivative.

[0248] Next, the treatment parameter determination algorithm 4328 calculates the treatment parameter (treatment pressure Pt) as follows:

[0249] Pt(t)=A*Φ(Π(t))+P0 (2)

[0250] Where P0 is the "DC" component of pressure, which may be a constant or may be a function of an index or measure of one or more of flow limitation, apnea, hypopnea, patency, and snoring. (Note: In CPAP or APAP therapy, A may be zero, in which case the therapeutic pressure equation (2) simplifies to Pt = P0).

[0251] In another form of the present technology, algorithm 4328 determines the treatment pressure Pt as a function of an index or measurement of one or more of flow limitation, apnea, hypopnea, patency, and snoring. In one embodiment, these measurements are determined based on a single breath rather than a collection of several previous breaths.

[0252] Figure 4E To illustrate method 4500 performed by processor 4230 in this form of the present technology, a flowchart is provided as one implementation of algorithm 4328. Method 4500 begins at step 4520, where processor 4230 compares a measure of the presence of apnea / hypopnea to a first threshold and determines whether the measure of the presence of apnea / hypopnea has exceeded the first threshold for a predetermined period of time, indicating that apnea / hypopnea is occurring. If so, method 4500 proceeds to step 4540; otherwise, method 4500 proceeds to step 4530. At step 4540, processor 4230 compares a measure of airway patency to a second threshold. If the measure of airway patency exceeds the second threshold, indicating that the airway is patent, the detected apnea / hypopnea is deemed central, and method 4500 proceeds to step 4560; otherwise, the apnea / hypopnea is deemed obstructive, and method 4500 proceeds to step 4550.

[0253] At step 4530 , processor 4230 compares the measure of flow limitation to a third threshold. If the measure of flow limitation exceeds the third threshold, indicating inspiratory flow limitation, method 4500 proceeds to step 4550 ; otherwise, method 4500 proceeds to step 4560 .

[0254] At step 4550, processor 4230 increases treatment pressure Pt by a predetermined pressure increment ΔP, assuming that the increased treatment pressure Pt does not exceed an upper limit Pmax. In one embodiment, the predetermined pressure increment ΔP and the upper limit Pmax are 1 cmH20 and 20 cmH20, respectively. Method 4500 then returns to step 4520.

[0255] At step 4560, processor 4230 decreases the treatment pressure Pt by a decrement, assuming that the reduced treatment pressure Pt does not fall below the lower limit Pmin. Method 4500 then returns to step 4520. In one embodiment, the decrement is proportional to the value of Pt-Pmin, such that in the absence of any detected event, the decrement Pt of the lower limit Pmin is exponential. Alternatively, the decrement Pt can be predetermined so that in the absence of any detected event, the decrement Pt of the lower limit Pmin is linear.

[0256] Detection of Cheyne-Stokes respiration4329

[0257] In one form of the present technology, one or more processors may implement one or more methods described herein for detecting Cheyne-Stokes respiration (CSR). For example, processor 4230 may execute algorithm 4329 to detect Cheyne-Stokes respiration (CSR). The one or more processors may be implemented, for example, in a PAP device that can provide respiratory therapy, in a computer that can analyze previously recorded flow data input to the computer, or in a monitoring / detection device (e.g., an invasive or non-invasive device) having a sensor that measures and analyzes a signal indicative of a patient's flow, which may or may not provide respiratory or other therapy.

[0258] In one form, the algorithm 4329 receives as input the respiratory flow rate Qr, a series of apnea and / or hypopnea events provided by the apnea and / or hypopnea determination algorithm 4325, and a series of half-breath markers and corresponding half-breath amplitudes provided by the respiratory framer 4319. The CSR detection algorithm 4329 processes these inputs "on the fly" and returns the parameters for each CSR event as quickly as possible or very soon after it occurs. In this regard, the CSR detection algorithm 4329 can be considered to operate in "real time." In one embodiment, the CSR event parameters are the start and end times of the CSR event.

[0259] Figure 6E Data from a Cheyne-Stokes patient is shown. Consecutive apnea events 6010, 6020, 6030 are marked.

[0260] Figure 6F Data from a patient with less severe Cheyne-Stokes respiration is shown. Consecutive hypopnea events 6110, 6120, 6130 are marked.

[0261] The period of time defined by consecutive apnea or hypopnea events is called the "event interval." Figure 6E 6120. An event interval may also end after a predetermined period of time (a "timeout condition") has passed without any apnea or hypopnea events. An event interval determined by the CSR detection algorithm 4329 to contain a CSR is referred to as a "CSR cycle." The initial work of the CSR detection algorithm 4329 is to determine which event intervals can be classified as CSR cycles and which other event intervals can be classified as upper airway obstruction (e.g., Figure 6D 4329) and is therefore not related to CSR. Once a series of consecutive event intervals has been determined to be a CSR cycle, the start of the first CSR cycle and the end of the last CSR cycle are used to distinguish the start and end of a "CSR event." The start and end times of each CSR event are returned by the CSR detection algorithm 4329.

[0262] Figure 8A flow chart illustrating a method 8000 that may be implemented by the CSR detection algorithm 4329 in one form of the present technology is included. The method 8000 begins at step 8010, which is an event handler that is continually executed to process each apnea or hypopnea event provided by the apnea / hypopnea determination algorithm 4325. Figure 9 The event handler 8010 is described in detail. The output of the event handler 8010 is a series of event intervals.

[0263] Upon receiving the event interval from the event handler 8010, step 8020 processes the event interval to determine its nature: positive indication (possibly a CSR cycle), negative indication (possibly not a CSR cycle), or no information. Figure 10 、 Figure 11 and Figure 12 Step 8020 is described in more detail. The next step 8030 updates the event interval statistics based on the characteristics determined in step 8020. Figure 13 Step 8030 is described in more detail. Finally, step 8040 analyzes the current event interval statistics to determine whether to change the CSR state. The CSR state, which can be a Boolean variable or other suitable data structure, indicates whether a CSR event has occurred. Figure 13 and Figure 14 Step 8040 is described in more detail.

[0264] Step 8040 applies a set of rules governing the interpretation of the current event interval statistics. Step 8040 considers a group of recent consecutive event intervals, such that if a positive indication of balance for the group is obtained, the group is considered to be part of a CSR event, and if a negative indication of balance is obtained, the group is considered not to be part of a CSR event. If the group also remains balanced, step 8040 does not change the current CSR state. The size of the group is defined by the number of event intervals, which may be accumulated over a longer history than the typical length of a CSR cycle.

[0265] Previous approaches for detecting CSRs collectively or holistically analyze multiple recent candidate CSR cycles to determine an overall CSR index score. This differs from current approaches, which independently characterize consecutive event intervals and detect CSRs based on a count of recent event interval characteristics. Because the current approach is less likely to be dominated by a single event interval, it can provide fewer false CSR detections, particularly those that are similar or non-similar to CSRs. This advantage is accentuated by analyzing a longer history of recent event intervals than in previous approaches.

[0266] Figure 9 In one form of the invention, Figure 8Schematic diagram of a hierarchical state machine (HSM) 9000 implemented by the event handler 8010 of method 8000. The HSM 9000 begins in state 9010, where it waits for a "first" apnea or hypopnea event. This "first" event is not necessarily the first event in the monitoring phase; it can be the first event after the end of a previous event interval due to a timeout condition. The arrival of the "first" apnea or hypopnea event starts an event interval and transitions the HSM 9000 to state 9020. Generally speaking, each event occurring after the "first" event ends the current event interval and starts a new event interval. The ended event interval is passed to step 8020 of method 8000 for processing. The exception to the general rule is that an apnea event causes any subsequent hypopnea event detected within a first predetermined time period (equivalent to the length of time that typical hypopneas can be ignored), the purpose of which is not to "double-handle" a single "low flow" event. In one embodiment of the HSM 9000, the first predetermined time period is less than 1 minute, for example, about half a minute (25 seconds long). That is to say, for example, a hypopnea event that occurs within 25 seconds of an apnea event will not end the current event interval or start a new event interval. For this reason, if the "first" event is an apnea event, state 9010 resets the "apnea timer."

[0267] In accordance with a timeout condition, if a second, longer predetermined period has elapsed since the previous event was processed, the current event interval ends and the HSM 9000 returns to state 9010, awaiting a new "first" event. To implement the timeout condition, state 9010 resets the "long timer" once the "first" event arrives. In one embodiment, the second predetermined period is longer than the first predetermined period and can be several minutes. For example, the second predetermined period can be 180 seconds, or approximately three minutes.

[0268] State 9020, which processes subsequent events, itself includes a state machine with sub-states 9030 and 9040. However, while in state 9020, if the long timer times out, i.e., a timeout condition occurs, the HSM 9000 ends the current event interval and returns to state 9010 to wait for the "first" event.

[0269] In substate 9030, which is the entry state, if the first event is a hypopnea, detection of a new / subsequent hypopnea event ends the current event interval, starts a new event interval, resets the long timer, and causes state 9020 to remain in substate 9030. Detection of a new / subsequent apnea event in substate 9030 ends the current event interval, starts a new event interval, resets the long timer and the apnea timer, and causes state 9020 to transition to substate 9040.

[0270] In substate 9040, which is the entry state, if the first event is apnea, the hypopnea event is ignored. An apnea event in substate 9040 ends the current event interval, starts a new event interval, resets the long timer and the apnea timer, and causes state 9020 to remain in substate 9040. Expiration of the apnea timer in substate 9040 causes state 9020 to return to substate 9030, where the hypopnea event can be processed.

[0271] Once an event interval is opened, subsequent occurrences of the half-breath marker signal (signaling that a half-breath has been completed) and the amplitude of the half-breath are calculated by the respiration framer 4329 for the CSR detection algorithm 4329. As the respiration framer 4329 signals each half-breath as complete and returns its amplitude, the CSR detection algorithm 4329 calculates a measure of respiratory ventilation and records the measure in a sequential buffer associated with the current open event interval. In one embodiment, the measure of respiratory ventilation is the product of the current half-breath amplitude and the amplitude of the previous half-breath. In other embodiments, the measure of respiratory ventilation can be the sum of the current half-breath amplitude and the previous half-breath amplitude, the current half-breath amplitude itself, the arithmetic or geometric mean of the previous two or more half-breath amplitudes, or some other low-pass filtered value of the most recent half-breath amplitude. Hereinafter, tidal volume is used as the half-breath amplitude, and the tidal volume product ("TVP") (which can be measured, for example, in squared liters) is used as the measure of respiratory ventilation. However, the described method can implement other measures of half-breath amplitude and respiratory ventilation.

[0272] There are exceptions to this general pattern of taking the product of the current half-breath tidal volume and the previous half-breath tidal volume for respiratory ventilation. The first exception is when the "first" hypopnea event occurs, the HSM 9000 is transitioned from the waiting state 9010 to the processing state 9020. The CSR detection algorithm 4329 may not record the previous half-breath tidal volume, and therefore, the tidal volume of the first half-breath occurring after the "first" hypopnea may be ignored. The second exception is that the first half-breath after any respiratory arrest may also be ignored because the tidal volume presented refers to the breath before the respiratory arrest and is therefore irrelevant. Hypopnea events after the "first" event are not handled in an exceptional manner, in the sense that the tidal volume available from the first half-breath is multiplied by the previous value and stored in a sequential buffer. The reason for this is that the hypopnea event is greatly delayed relative to the lowest point of the tidal volume, and therefore the value recorded may be associated with the most recently opened event interval.

[0273] In one embodiment, the sequential buffer associated with the currently open event interval may have limited space (e.g., only room for data for 125 half-breath tidal volume products (TVPs)). Typically, in most true CSR events, there will be no more than this limit for half-breaths in an event interval. Once the event interval ends, the contents of the sequential buffer are forwarded to step 8020 as a series of TVPs associated with the event interval, and the sequential buffer begins to be overwritten by the TVP associated with the most recently opened event interval (if any).

[0274] Figure 10 Contains instructions for implementing the present technology in one form Figure 8 8000 of the method 1000 is a flow chart of the event interval processing step 8020 of the method 8000.

[0275] Method 10000 begins at step 10010, which checks whether the event interval has ended due to a timeout condition. If so ("Y"), step 10020 marks the event interval so that subsequent processing at step 8040 terminates the current CSR event, if one is currently being processed, and method 10000 ends. Otherwise ("Y"), method 10000 proceeds to step 10030 to check: (a) the number of non-zero TVPs in the TVP sequence associated with the event interval and (b) the duration of the interval. For example, if there are fewer than a minimum number of non-zero TVPs or the event interval duration is outside the duration range of a typical CSR cycle ("Y"), then at step 10040, the event interval is characterized as a negative indication and method 10000 ends. In one embodiment, the duration range is approximately 30 seconds to 125 seconds, and the minimum number of non-zero TVPs is three. Otherwise (“N”), at step 10050 , the minimum value TVPmin and the maximum value TVPmax of the TVP in the sequence are found and recorded.

[0276] Step 10060 then calculates the value of a feature called "relative maximum phase" (thought of as a "jump" or sudden rise). The relative maximum phase feature is calculated as the maximum value of the difference between consecutive TVPs in the sequence, normally denoted as TVPmax. The first difference is simply set to the first TVP in the sequence. The significance of the relative maximum phase feature is that the presence of a relatively sudden and large rise in the TVP sequence of an event interval indicates that the event interval is obstructive in nature, rather than due to a CSR.

[0277] Step 10070 determines the nature of the event interval (positive indication, negative indication, or no indication). The nature of the processing at step 10070 depends on whether the event interval ends with an apnea event or a hypopnea event, that is, at its "end event". Figure 11 and Figure 12 Step 10070 is described in more detail below. Method 10000 then ends.

[0278] Figure 11 A flow chart is included that illustrates a method 11000 that may be implemented as an event interval characterization step 10070 in one form of the present technology where the event interval ends due to a hypopnea event. The method 11000 begins at step 11010 by constructing a proportional TVP template based on a normalized template representing an expected sequence of TVP values ​​consistent with an event interval leading to a CSR hypopnea (see Figure 6F ). The normalization template is defined to range between 0 and 1 in the domain [0, 1]. The number of values ​​in the normalization template is set to equal the number of TVPs in the TVP sequence. The zero value of the normalization template occurs slightly before the end of the domain so that it matches the actual position of the hypopnea at the end event interval, which is slightly before the hypopnea event due to the delay in the hypopnea detection portion of the algorithm 4325.

[0279] In one embodiment of step 11010, the normalization template is constructed using the following functional form:

[0280]

[0281] Step 11010 constructs a scaled TVP template by scaling the normalized template y(x) to the interval [TVPmin, TVPmax] as follows:

[0282] ScaledTemplate(x)=y(x)(TVPmax-TVPmin)+TVPmin (4)

[0283] Step 11020 then calculates the difference between the TVP sequence and the proportional TVP template. A low difference value indicates that the event interval has characteristics that lead to CSR hypopnea. In one embodiment, the difference is the root mean square (RMS) deviation of the TVP sequence from the proportional TVP template.

[0284] The remaining steps 11030 through 11070 of method 11000 apply a rule for evaluating the jump-up feature value, the difference, and the duration of the event interval to determine its characteristics. At step 11030, the jump feature value is compared to a threshold value J1. If the jump feature value is greater than the threshold value J1 ("Y"), then at step 11040, the event interval is characterized as a negative suggestion. Otherwise ("N"), if the event interval duration is greater than the threshold value D1 and the difference in the TVP sequence from the proportional TVP template is less than the threshold value R1 ("Y" at step 11050), then at step 11060, the event interval is characterized as a positive suggestion. Otherwise ("N"), at step 11070, the event interval is labeled as non-informative. In one embodiment, the rule thresholds are J1 = 0.6, D1 = 35 seconds, and R1 = 0.2 square liters.

[0285] Figure 12 A flow chart is included that illustrates a method 12000 that may be implemented as an event interval characterization step 10070 in one form of the present technology when the event interval ends due to an apnea event. The method 12000 begins at step 12010 by constructing two proportional TVP templates based on corresponding normalized templates, one of which represents an expected sequence of TVP values ​​consistent with an event interval leading to an OSA event (see Figure 6D ), while the other template represents the expected sequence of TVP values ​​consistent with the interval of events leading to CSR apnea (see Figure 6E ). The normalized template is defined to range between 0 and 1 in the domain [0,1]. The number of values ​​in each normalized template is set to be equal to the number of TVPs in the TVP sequence. In one embodiment of step 12010, the normalized OSA template is constructed using the following functional form:

[0286]

[0287] In one embodiment of step 12010, the normalized CSR template is constructed as the product of a raised half-wave cosine function and a log-normal distribution parameterized by the average of the scale parameters of 0 and 1, which is normalized so that the peak of the normalized CSR template reaches an amplitude of 1. That is, the normalized CSR template can be constructed using the following function form

[0288]

[0289] Step 12010 constructs two scaled TVP templates (scaled OSA template and scaled CSR template) by scaling each normalized template y(x) to the interval [TVPmin, TVPmax] according to equation (4).

[0290] Step 12020 then calculates the difference between the TVP sequences based on the proportional OSA template and the proportional CSR template, generating two numerical values ​​that can be considered "unlike OSA scores" and "unlike CSR scores," respectively. These are called "unlike" scores because the smaller the score, the closer the recorded TVP value is to the associated template, and conversely, the larger the score, the less similar the recorded TVP value is to the template. A zero difference is achieved only when the recorded TVP exactly matches the corresponding template. In one embodiment, the difference is calculated as an RMS deviation.

[0291] At step 12025, a combined normalized score, called a "CSR similarity score," is calculated from the unlike-OSA score and the unlike-CSR score. The CSR similarity score is the minimum of the recorded TVPs for the perfect match ratio OSA template and the maximum of the recorded TVPs for the perfect match ratio CSR template. In one embodiment, step 12025 calculates the CSR similarity score by taking the difference between the unlike-OSA score and the unlike-CSR score and dividing the result by the larger of the two scores. The resulting CSR similarity score is in the range of -1 (for the recorded TVPs for the perfect match ratio OSA template) to +1 (for the recorded TVPs for the perfect match ratio CSR template).

[0292] The remaining steps 12030 through 12070 of method 12000 apply a rule for evaluating the jump feature value, the CSR similarity score, and the duration of the event interval to determine its characteristics. At step 12030, the jump feature value is compared to a threshold value J2. If the jump feature value is greater than the threshold value J2 ("Y"), then at step 12040, the event interval is characterized as a negative suggestion. Otherwise ("N"), if the event interval duration is greater than the threshold value D2 and the CSR similarity is greater than the threshold value R2 ("Y" at step 12050), then at step 12060, the event interval is characterized as a positive suggestion. Otherwise ("N"), at step 12070, the event interval is marked as non-informative. In one embodiment, the rule thresholds are J2 = 0.6, D2 = 40 seconds, and R2 = -0.15.

[0293] As previously described, the determination at step 8040 regarding whether a CSR event is currently occurring can be further refined by considering additional event intervals, such as all event intervals that have been processed in a history longer than the typical length of a CSR cycle. At step 8040, event intervals longer than the history duration are not considered. In one embodiment, this history can be several minutes or hours, for example, a duration of 19 minutes. However, other such history durations can be selected to provide an appropriate historical assessment.

[0294] Step 8040 determines whether to set or change the CSR status based on any one or more (e.g., all) of the total count of event intervals in the history, the number of event intervals in the history that were positively indicated, and the number of event intervals in the history that were negatively indicated. (Other criteria may also be applied / evaluated, such as whether the event interval ended due to a timeout condition or end of treatment.)

[0295] Step 8040 utilizes the event interval statistics that have been updated based on the most recently completed event at step 8030. Step 8030 may optionally be implemented to maintain a b Statistics in the ring buffer of memory blocks, N b Each of the memory blocks corresponds to one of a series of windows of equal duration into which the history is conceptually divided. Each memory block is configured to contain records comprising counts from event intervals, for example, three different types of counts of event intervals that have ended in the corresponding window. For example, the different types of counts may include one or more of: the number of event intervals having a positive prompt characteristic, the number of event intervals having a negative prompt characteristic, and the total number of event intervals for the corresponding window, including non-informative event intervals and those event intervals that ended due to a timeout condition. For the reasons described below, the duration of each window is the temporal resolution of the CSR detection algorithm 4329, and therefore the window duration is selected to be approximately equivalent to the length of the CSR cycle. In one form, the duration of each window is 30 seconds. The number of memory blocks in the ring buffer, N, is: b is the length of the history divided by the window duration. In one embodiment, when the duration of the history is 19 seconds and the duration of each window is 30 seconds, there are N b = 38 memory blocks (19 minutes / 30 seconds). Although a circular buffer is described in the example, other data structures may be implemented in the statistical collection / evaluation of counts for CSR status determination.

[0296] When the HSM 9000 is in the waiting state 9010, the index of the current storage block remains at 1. Once the HSM 9000 has entered the "process subsequent events" state 9020, step 8030 increments the index by 1 after each successive window has passed (calculating N b ) until the HSM 9000 returns to wait state 9010. Step 8030 increments only the relevant count in the current memory block (the total count in each case, and possibly subsequently the positive hint count or the negative hint count), depending on the nature of the event interval just completed and processed by step 8020.

[0297] Figure 13 Indicates the use of N in the ring bufferb = Example 13000 of the evolution of the contents of an example circular buffer for an implementation with 38 memory blocks. The memory blocks are numbered 1 to 38 from right to left. The current memory block is white, with earlier memory blocks represented by progressively darker fills. The memory block numbers represent the counts for each memory block; from top to bottom, they are: the number of positive cues, the number of negative cues, and the total number of event intervals. Row 13010 depicts the state of the circular buffer shortly after the end of the first event interval, where all memory blocks except the current memory block (numbered 1) have all zero counts, and the current memory block has a positive count of 1 when step 8020 determines that the event interval is a negative cue. Row 13020 depicts the state of the circular buffer shortly before 19 minutes had passed. The current memory block is now numbered 37, and all illustrated memory blocks have at least one event interval recorded in them. Row 13030 depicts the state of the circular buffer shortly after 20.5 minutes have passed. The current memory block number is 3, and the counts previously stored in memory blocks 1, 2, and 3 have been overwritten using the new technique associated with the most recently completed event interval.

[0298] After processing the event intervals at step 8020 and updating the event interval statistics at step 8030, step 8040 analyzes the event interval statistics.

[0299] Figure 14 A flow chart illustrating a method 14000 that may be used to implement step 8040 in one form of the present technology is included.

[0300] Method 14000 begins at step 14010, which checks whether the event interval has ended due to a timeout condition (as indicated by step 14020). If so ("Y"), step 14015 determines that the current CSR event (if one is in progress) has ended and sets the CSR status to false. The end time of the just-ended CSR event is the current time. Optional step 14020 then adjusts the end time of the just-ended CSR event as described below. At the next step 14070, any count that may exist in the ring buffer is cleared, and method 14000 ends at step 14090.

[0301] Otherwise ("N" at step 14010), step 14025 checks whether the statistical history recorded in the ring buffer is longer than a threshold value slightly less than the maximum possible length of the history. This step includes checking the oldest stored block in the history using a non-zero total event interval count. In one embodiment where the duration of the history is 19 minutes, this threshold value is 15 minutes. If not ("N"), method 14000 ends at step 14030 because there is insufficient information to change the CSR state.

[0302] Otherwise ("Y" at Step 14025), Method 14000 proceeds to Step 14035, which calculates three counts based on the statistics recorded in the ring buffer.

[0303] ·C + = the number of positive cue event intervals in history

[0304] ·C - = the number of negative cue event intervals in history

[0305] ·C T = the total number of event intervals in history

[0306] Step 14040 then determines whether the three counts meet the criteria indicating that a CSR event has begun. The "start" criterion ensures that there have been enough event intervals in the history to form a reliable determination, and that the number of positive event intervals is equal to the total number of event intervals and greater than the number of negative event intervals. In one embodiment, the three start criteria are as follows:

[0307]

[0308] in is the floor operator and H is the history length (in minutes). If all start criteria are met ("Y" at step 14040), step 14045 determines that a CSR event has started and sets the CSR status to true. The start time of the just-started CSR event is the current time. Optional step 14050 then adjusts the start time of the CSR event as described below. Method 14000 then proceeds to step 14070 to clear the ring buffer, as described above.

[0309] If the start criteria are not met ("N" at step 14040), step 14055 determines whether the three counts meet the criteria indicating that the CSR event has ended. The end criteria ensures that there have been enough event intervals in the history to form a reliable decision, and that the number of event intervals that negate the prompt is equivalent to the total number of event intervals. In one embodiment, the two "end" criteria are as follows:

[0310]

[0311] If all end criteria are met ("Y" at step 14055), step 14060 determines that the current CSR event has ended and sets the CSR status to false. The end time of the just-ended CSR event is the current time. Optional step 14065 then adjusts the end time of the just-ended CSR event as described below. Method 14000 then proceeds to step 14070 to clear the ring buffer, as described above.

[0312] If the ending criteria are not met (“N” at step 14055 ), method 14000 ends at step 14090 .

[0313] The adjustment of the start and end times at optional steps 14020, 14050, and 14065 will now be described. Due to the discretion of the CSR detection algorithm 4329, the moment a CSR event is determined to begin or end can (and likely is) a long time after the CSR event actually begins or ends. Since the CSR detection algorithm 4329 returns the start and end times for each CSR event, steps 14020, 14050, and 14065 perform some backtracking to find the most appropriate time to return those start and end times.

[0314] Once step 14015 determines that the CSR event has ended due to a timeout condition, step 14020 adjusts the end time of the CSR event by subtracting the duration of the HSM9000's "long timer", which in one embodiment is equal to 3 minutes.

[0315] Once step 14045 determines that a CSR event has started, step 14050 adjusts the start time of the CSR event by subtracting the elapsed duration of the CSR event, which is the earliest record (from the start of the record) in the ring buffer containing a non-zero positively implied event interval count in the event that the CSR event is determined to have started.

[0316] Once step 14060 determines that the CSR event has ended due to event interval statistics, step 14065 adjusts the end time of the CSR event to the time of completion of the most recent record in the circular buffer containing a non-zero positively implied event interval count.

[0317] Since the resolution of the usage recorded in the history is the duration of the window corresponding to the storage block, the elapsed duration also has a resolution equal to the duration of the window (30 seconds in the embodiment described above). Therefore, the adjusted start and end times have a resolution equal to the window duration.

[0318] When implemented in a PAP device, an additional scenario can be addressed during the decision process. In some cases, the PAP device 4000 can be set by the user to a standby mode indicating "end of treatment" (for example, because a salesperson is conducting a product demonstration). In this case, there are two possibilities, depending on whether the most recent event interval that was not characterized as non-informative was a positive or negative prompt. If it was a positive prompt, the end time of the CSR event is set to the time when the PAP device 4000 was set to standby mode. If it was a negative prompt, the end time of the CSR event is set to the start time of the event interval of the negative prompt. Therefore, the time can be set based on the mode of the PAP device (e.g., standby mode).

[0319] In all cases, the elapsed duration is calculated from the start time (adjusted) to the end time (adjusted) to indicate the duration of the CSR event.

[0320] The thresholds and templates defined above are specifically chosen to distinguish between CSR cycles and OSA event cycles, which is why algorithm 4329 is described as a "CSR detection" algorithm. However, by using other values ​​for the thresholds and templates, algorithm 4329 can be applied to distinguish between other forms of periodic breathing interrupted by apneas or hypopneas (e.g., complex sleep apneas) and OSA cycles. For this reason, algorithm 4329 can be more generally described as a "periodic breathing detection" algorithm.

[0321] Figure 15A Graphs illustrating the operation of the CSR detection algorithm 4329 are included. The upper trace (trace 15000) represents respiratory flow Qt over a period of approximately 8 minutes. The lower trace 15030 represents the CSR state calculated using the CSR detection algorithm 4329 based on the respiratory flow trace 15000. The respiratory flow trace 15000 begins with normal breathing, followed by a series of CSR cycles (e.g., 15020), each of which includes a complete respiratory arrest (e.g., 15010). The CSR state trace 15030 shows that the CSR state is not set to true by normal breathing, but rises to true at time 15040 shortly after the respiratory arrest 15010 of the first CSR cycle ends, and remains true for the remainder of the trace 15030 as the CSR event continues.

[0322] Figure 15BContains a graph further illustrating the operation of the CSR detection algorithm 4329. The upper trace (trace 15050) represents the respiratory flow Qt over approximately 7 minutes. The lower trace 15090 represents the CSR state calculated using the CSR detection algorithm 4329 based on the respiratory flow trace 15050. The respiratory flow trace 15050 begins with normal breathing, followed by a series of CSR cycles (e.g., 15070), each of which contains a complete obstructive apnea (e.g., 15060) followed by a rapid recovery (e.g., 15080). The CSR state trace 15090 shows that the CSR state was not set to true at any stage by normal breathing or OSA cycles in the respiratory flow trace 15050.

[0323] Figure 16 Contains graphs whose illustrations are based on Figure 15B False positive CSR identification in the operation of a CSR detection algorithm (EncorePro 2) implemented on a current market device (Respironics REMStar Pro 2) using the same flow signal. Figure 16 , trace 16000 represents respiratory flow Qt over approximately 12 minutes. Respiratory flow trace 16000 shows a series of OSA cycles (e.g., 16010), each containing a complete obstructive apnea (e.g., 16020) followed by a rapid recovery (e.g., 16030). The gray shaded area 16040 indicates that the CSR detection algorithm incorrectly detects the presence of CSR, which begins around 8 minutes and continues to the end of respiratory flow trace 16000.

[0324] Control Module 4330

[0325] In one form of the present technology, a control module 4330 according to an aspect of the present technology receives as input one or more treatment parameters and controls the treatment device 4245 to deliver treatment based on the treatment parameters.

[0326] In one form of the present technology, the treatment parameter is a target treatment pressure Pt.

[0327] In another form of the present technology, a control module 4330 according to an aspect of the present technology receives EPAP pressure and IPAP pressure as inputs and controls the therapy device 4245 to deliver these respective pressures in synchronization with the expiratory and inspiratory phases of the respiratory cycle, respectively.

[0328] In one form of the present technology, the control module 4330 is responsive to any CSR event parameters provided by the CSR detection algorithm 4329 to adjust the treatment parameters provided by the treatment parameter determination algorithm 4328 to mitigate the CSR.

[0329] Report Module 4335

[0330] The reporting module 4335 sends data from one or more of the pre-treatment and therapy engine processing modules 4310 and 4320 to the data communication interface 4280. In one form of the present technology, the reporting module 4335 reports any CSR event parameters provided by the CSR detection algorithm 4329 to the data communication interface 4280. The reported data may be stored in the memory 4260 of the PAP device 4000 and / or forwarded to local or remote external communication networks 4284 and 4282 via the data communication interface 4280. In some forms of the present technology, the processor 4230 may display details of the detected CSR event on the output device 4290.

[0331] Detection of fault conditions 4340

[0332] In one form of the present technology, the processor 4230 executes one or more methods for detecting a fault condition. Preferably, the fault condition detected by the one or more methods includes at least one of the following:

[0333] Power failure (no power, or insufficient power)

[0334] Converter fault detection

[0335] Unable to detect the presence of components

[0336] Operating parameters outside recommended ranges (e.g., pressure, flow, temperature, PaO2)

[0337] The test alarm failed to produce a detectable alarm signal

[0338] Upon detecting a fault condition, the corresponding algorithm signals the presence of the fault by one or more of the following:

[0339] Start an audible, visual, and / or dynamic (e.g., vibration) alarm

[0340] Sending messages to external devices

[0341] Record of events

[0342] Treatment Device 4245

[0343] In a preferred form of the present technology, treatment device 4245 delivers treatment to patient 1000 under the control of control module 4330.

[0344] Preferably, the treatment device 4245 is a pressure device 4140 as described above.

[0345] Monitoring system

[0346] Another form of the present technology includes an apparatus for monitoring a respiratory disorder patient 1000. The apparatus may include a monitoring device 7000 configured to monitor the respiratory motion of the patient 1000.

[0347] In one embodiment, monitoring device 7000 includes components similar to the following components of PAP device 4000 : processor 4230 , clock 4232 , power supply 4210 , memory 4260 , and data communication interface 4280 .

[0348] Monitoring device 7000 also includes a non-contact sensor that generates a signal representing the respiratory motion of patient 1000. In one embodiment, the non-contact sensor generates the respiratory motion signal by delivering an RF pulse or series of pulses to patient 1000 and analyzing the chest response of patient 1000. Processor 4230 (typically a processor) of monitoring device 7000 is configured to execute the aforementioned algorithm 4330 (in addition to treatment parameter determination algorithm 4328 and control module 4330) using the respiratory motion signal provided by the non-contact sensor as the respiratory air flow rate Qr.

[0349] In other forms of the present technology, apparatus for monitoring a respiratory disorder patient 1000 includes different monitoring devices utilizing sensors configured to provide respiratory motion signals according to different modalities, such as a chest strap (plethysmograph).

[0350] In other forms, the monitoring device may be an implantable device, such as a cardiac resynchronization therapy (CRT) device and / or a defibrillator, such as a defibrillator that uses one or more implanted electrodes to measure respiratory motion or other signals indicative of respiration.

[0351] Glossary

[0352] For purposes of this technical disclosure, in some forms of the technology, one or more of the following definitions may apply. In other forms of the technology, alternative definitions may apply.

[0353] General Principles

[0354] Air: In some forms of the present technology, the air supplied to the patient may be atmospheric air, and in other forms of the present technology, the atmospheric air may be supplemented with oxygen.

[0355] Continuous Positive Airway Pressure (CPAP): Taking CPAP therapy means applying a supply of air or breathable gas to the airway entrance at a continuous positive pressure relative to atmosphere, and preferably at a constant pressure, throughout the patient's breathing cycle. In some forms, the pressure at the airway entrance will vary by several centimeters of water during a single breathing cycle, e.g., higher during inspiration and lower during expiration. In some forms, the pressure at the airway entrance is slightly higher during expiration and slightly lower during inspiration. In some forms, the pressure will vary between different breathing cycles of the patient, e.g., increasing in response to detecting an indication of partial upper airway obstruction and decreasing when there is no indication of partial upper airway obstruction.

[0356] Aspects of PAP Devices

[0357] Air Circuit: A conduit or tube constructed and arranged to carry air or a supply of breathable gas between a PAP device and a patient interface, when in use. Specifically, the air circuit may be fluidly connected to the outlets of the pneumatic block and the patient interface. The air circuit may also be referred to as an air delivery tube. In some cases, there may be separate branches of the circuit for inspiration and expiration. In other cases, a single branch is used.

[0358] APAP: Automatically adjusts positive airway pressure. Positive airway pressure is continuously adjusted between a minimum and maximum limit, depending on the presence or absence of an indication of an SDB event.

[0359] Blower or flow generator: A device that delivers a flow of air at a pressure higher than ambient pressure.

[0360] Controller: A device or part of a device that adjusts its output based on its input. For example, one form of controller has a variable under control, the controlled variable, which constitutes the input to the device. The output of the device varies with the current value of the controlled variable and the variable's set point.

[0361] Therapy: Therapy in this context can be one or more of positive pressure therapy, oxygen therapy, carbon dioxide therapy, control of enclosed space, and administration of medication.

[0362] Positive Airway Pressure (PAP) Device: A device used to provide a positive pressure supply of air to the airways.

[0363] Transducer: A device used to convert one form of energy or signal into another. A transducer can be a sensor or detector that converts mechanical energy (e.g., motion) into an electrical signal. Examples of sensors include pressure sensors, flow sensors, carbon dioxide (CO2) sensors, oxygen (O2) sensors, strain sensors, motion sensors, noise sensors, plethysmographs, and cameras.

[0364] Aspects of the respiratory cycle

[0365] Apnea: Preferably, apnea will be said to occur when flow drops below a predetermined threshold for a duration of, for example, 10 seconds. Obstructive apnea will be said to occur when some obstruction in the airway does not allow air to flow (despite the patient's efforts). Central apnea will be said to occur when apnea is detected due to a decrease in respiratory effort or an absence of respiratory effort.

[0366] Breathing rate: The patient's spontaneous breathing rate, usually measured in breaths per minute.

[0367] Duty cycle: The ratio of inspiratory time Ti to total breathing time Ttot.

[0368] (Respiratory) effort: Preferably, respiratory effort will be the movement accomplished by a spontaneous breather attempting to breathe.

[0369] Expiratory portion of a breathing cycle: The period from the start of the respiratory flow to the start of the inspiratory flow.

[0370] Flow limitation: Preferably, flow limitation will be considered a state of the patient's breathing in which an increased effort by the patient does not result in a corresponding increase in flow. When flow limitation occurs during the inspiratory portion of the breathing cycle, the flow limitation may be described as inspiratory flow limitation. When flow limitation occurs during the expiratory portion of the breathing cycle, the flow limitation may be described as expiratory flow limitation.

[0371] Half-breath: The inhalation or exhalation portion of the respiratory cycle.

[0372] Hypopnea: Preferably, hypopnea is considered a decrease in flow, but not a cessation of flow. In one form, hypopnea is said to occur when flow decreases below a threshold for a sustained period of time. In one form, in an adult, any of the following may be considered hypopnea:

[0373] (i) The patient's respiration rate decreases by 30% for at least 10 seconds with an associated 4% desaturation; or

[0374] (ii) The patient's breathing is reduced (but less than 50%) for at least 10 seconds, plus an associated desaturation or arousal of at least 3%.

[0375] Inspiratory portion of a breathing cycle: Preferably, the period from the start of inspiratory flow to the start of expiratory flow will be considered the inspiratory portion of a breathing cycle.

[0376]

[00145] Patency (Airway): The degree to which the airway is open, or the extent to which the airway is open. A patent airway is open. Airway patency can be quantified, for example, with a value of one (1) indicating open and a value of zero (0) indicating closed.

[0377] Positive End-Expiratory Pressure (PEEP): The pressure above atmospheric pressure that exists in the lungs at the end of exhalation.

[0378] Peak flow (Qpeak): The maximum flow value during the inspiratory portion of the respiratory flow waveform.

[0379] Respiratory flow, airflow, patient airflow, respiratory airflow (Qr): These synonymous terms should be understood to refer to the estimate of respiratory airflow of the PAP device, rather than the "correct respiratory flow" or "correct respiratory airflow", which is the actual respiratory flow experienced by the patient, usually expressed in liters per minute.

[0380] Tidal volume (Vt): The amount of air inhaled or expired during normal breathing when no extra effort is exerted.

[0381] (Inspiratory) Time (Ti): Duration of the inspiratory portion of the respiratory flow waveform.

[0382] (Expiratory) Time (Te): Duration of the expiratory portion of the respiratory flow waveform.

[0383] (Total) 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 immediately following respiratory flow waveform.

[0384] Typical recent ventilation: The ventilation value around which recent values ​​within some predetermined timescale tend to cluster, ie a measure of the central tendency of recent ventilation values.

[0385] Upper airway obstruction (UAO): includes both partial and total upper airway obstruction. This can be associated with a flow-limited state where flow levels increase only slightly or may even decrease as the pressure differential across the upper airway increases (Starling resistance behavior).

[0386] Ventilation Volume (Ventilation): A measure of the total amount of gas exchanged by a patient's respiratory system, including both inspiratory and expiratory flow per unit time. When expressed as volume per minute, this quantity is often referred to as "minute ventilation." Minute ventilation is sometimes given simply as volume, understood as volume per minute.

[0387] PAP device parameters

[0388] Flow rate: The instantaneous volume (or mass) of air delivered per unit time. Flow rate is measured over a very short period of time when flow rate and ventilation volume have the same volume or mass size per unit time. Flow may nominally be positive for the inspiratory portion of a patient's breathing cycle and therefore negative for the expiratory portion of the patient's breathing cycle. In some cases, reference to flow rate will be to a scalar quantity (i.e., a quantity having only magnitude). In other cases, reference to flow rate will be to a vector quantity (i.e., a quantity having both magnitude and direction). Flow rate will be given a sign, Q. Total flow, Qt, is the flow rate of air leaving the PAP device. Ventilator flow, Qv, is the flow rate of air leaving the ventilator to expel exhaled gas. Leakage flow, Ql, is the flow rate of unintentional leakage from the patient interface system. Respiratory flow, Qr, is the flow rate of air received into the patient's respiratory system.

[0389] Leak: The word "leak" can be thought of as the flow of air to the environment. Leaks can be intentional, for example, to expel exhaled CO2. Leaks can be unintentional, for example, due to an incomplete seal between the nasal mask and the patient's face.

[0390] Other notes

[0391] The disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent files or records, but otherwise reserves all copyright rights whatsoever.

[0392] Unless the context clearly dictates otherwise and where various values ​​are provided, it should be understood that each intervening value (to one-tenth of the unit of the lower limit) between the upper and lower limits of the stated range and any other stated or intervening value in the stated range is encompassed within the present technology. The upper and lower limits of these intervening ranges (which may independently be included in the intervening ranges) are also encompassed within the present technology, subject to any specifically excluded limits in the stated ranges. When the stated range includes one or both limits, ranges excluding either or both of those included limits are also encompassed within the present technology.

[0393] Furthermore, where one or more values ​​are stated herein as implemented as part of the present technology, it should be understood that unless otherwise indicated, these values ​​may be approximate and that these values ​​may be used to any suitable number of significant digits as may be permitted or required by practical technical implementations.

[0394] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this technology belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of this technology, a limited number of exemplary methods and materials are described herein.

[0395] When a particular material is identified as being preferably used to construct a component, it is apparent that alternative materials having similar properties may be used as substitutes. Furthermore, unless otherwise specified, any and all components described herein should be understood to be capable of being manufactured, and also to be manufactured together or separately.

[0396] It must be noted that as used herein and in the appended claims, the singular forms "a," "an," and "the" include plural equivalents unless the context clearly dictates otherwise.

[0397] All publications mentioned herein are incorporated by reference into the disclosure and description of the method and / or material of the themes belonging to these publications. The publication discussed herein is only provided for its disclosure before the application's filing date. Any content herein can not be construed as admitting that this technology has no right to advance by means of this publication date previously invented. In addition, the publication date provided can be different from actual publication date, and it may need to confirm independently.

[0398] Moreover, in interpreting this disclosure, all terms should be interpreted in the broadest reasonable manner consistent with the content. Specifically, the term "comprising" should be interpreted as referring to elements, components or steps in a non-exclusive manner, indicating that the referenced elements, components or steps may be present, utilized or combined with other elements, components or steps not explicitly referenced.

[0399] The subject headings used in the detailed description are included for the convenience of the reader and should not be used to limit the subject matter found in the entire disclosure or claims. The subject headings should not be used to constitute the scope of the claims or claim limitations.

[0400] Although the present technology has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely illustrative of the principles and applications of the present technology. In some instances, terms and symbols may imply specific details that are not required to practice the present technology. For example, although the terms "first" and "second" may be used, unless otherwise specified, they are not intended to indicate any order, but rather to distinguish different elements. Furthermore, although the processing steps in the method may be described or illustrated in an order, such order is not required. Those skilled in the art will recognize that such order may be modified and / or aspects thereof may be performed simultaneously or even synchronously.

[0401] It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present technology.

[0402] Reference Mark List

[0403] Patient 1000

[0404] Bed Partner 1100

[0405] Patient Interface 3000

[0406] Sealing forming structure 3100

[0407] Inflatable Chamber 3200

[0408] Positioning and stabilizing structures 3300

[0409] Ventilation port 3400

[0410] Connection port 3600

[0411] Forehead support 3700

[0412] PAP Device 4000

[0413] External housing 4010

[0414] Upper part 4012

[0415] Lower part 4014

[0416] Panel 4015

[0417] Chassis 4016

[0418] Handle 4018

[0419] Pneumatic block 4020

[0420] Pneumatic components 4100

[0421] Air filter 4110

[0422] Inlet air filter 4112

[0423] Outlet air filter 4114

[0424] Muffler 4120

[0425] Inlet muffler 4122

[0426] Outlet muffler 4124

[0427] Pressure Device 4140

[0428] Blower 4142

[0429] Motor 4144

[0430] Check Valve 4160

[0431] Air circuit 4170

[0432] Supplemental oxygen 4180

[0433] Electrical Components 4200

[0434] Circuit Board Assembly PCBA 4202

[0435] Power Supply 4210

[0436] Input device 4220

[0437] Processor 4230

[0438] Clock 4232

[0439] Treatment device controller 4240

[0440] Treatment Device 4245

[0441] Protection circuit 4250

[0442] Memory 4260

[0443] Converter 4270

[0444] Pressure Converter 4272

[0445] Flow Converter 4274

[0446] Motor speed signal 4276

[0447] Data Communication Interface 4280

[0448] Remote External Communication Network 4282

[0449] Local external communication network 4284

[0450] Remote External Device 4286

[0451] Local external device 4288

[0452] Output device 4290

[0453] Display Driver 4292

[0454] Display 4294

[0455] Algorithm 4300

[0456] Preprocessing module 4310

[0457] Pressure Compensation Algorithm 4312

[0458] Ventilation port flow calculation algorithm 4314

[0459] Leakage flow calculation algorithm 4316

[0460] Respiratory Flow Algorithm 4318

[0461] Breathing Framer 4319

[0462] Treatment Engine Module 4320

[0463] Phase determination algorithm 4321

[0464] Waveform determination algorithm 4322

[0465] Forming ventilation determination algorithm 4323

[0466] Traffic Limitation Determination Algorithm 4324

[0467] Apnea / Hypopnea Determination Algorithm 4325

[0468] Snoring Detection Algorithm 4326

[0469] Airway Patency Algorithm 4327

[0470] Treatment parameter determination algorithm 4328

[0471] CSR Detection Algorithm 4329

[0472] Control Module 4330

[0473] Report Module 4335

[0474] Fault condition detection module 4340

[0475] Method 4500

[0476] Humidifier 5000

[0477] Humidifier Controller 5250

[0478] Respiratory arrest event 6010

[0479] Respiratory arrest event 6020

[0480] Respiratory arrest event 6030

[0481] Event interval 6040

[0482] Hypopnea event 6110

[0483] Hypopnea event 6120

[0484] Hypopnea event 6130

[0485] Monitoring Device 7000

[0486] Method 8000

[0487] Event Handler 8010

[0488] HSM 9000

[0489] Method 10000

[0490] Method 11000

[0491] Method 12000

[0492] Instance 13000

[0493] Line 13010

[0494] Line 13020

[0495] Line 13030

[0496] Method 14000

[0497] Trace 15000

[0498] Respiratory arrest 15010

[0499] CSR Cycle 15020

[0500] Trace 15030

[0501] Time 15040

[0502] Trace 15050

[0503] Respiratory arrest 15060

[0504] OSA Cycle 15070

[0505] Restore 15080

[0506] Trace 15090

[0507] Trace 16000

[0508] OSA Cycle 16010

[0509] Respiratory arrest 16020

[0510] Restore 16030

[0511] Shaded area 16040

Claims

1. A computer-readable storage medium storing program code instructions, wherein the program code instructions are configured to cause a processor to perform a method for detecting periodic breathing of a patient, the method comprising: receiving a series of event intervals defined by apnea or hypopnea events detected in the respiration of the patient; At the end of an event interval, the event interval is processed to determine a characteristic of the event interval, wherein the characteristic of the event interval is determined using a set of characteristic descriptions including: (a) the event interval is determined to be likely to be a periodic respiratory cycle; (b) the event interval is determined to be unlikely to be a periodic respiratory cycle; and (c) if the event interval is determined to be neither (a) nor (b), the event interval is determined to be non-informative; and determining whether to change a current periodic breathing state indicating whether a periodic breathing event is ongoing based on a history of event interval characteristics that are longer than a typical length of a periodic breathing cycle, Therein, the processing depends on a sequence of respiratory ventilation measurements associated with the event interval.

2. The computer-readable storage medium according to claim 1, wherein: The method further includes reporting parameters of the detected periodic respiratory events.

3. The computer-readable storage medium of claim 1, wherein the patient is undergoing treatment for a breathing disorder, further comprising adjusting one or more parameters of the treatment in response to detected periodic respiratory events.

4. The computer-readable storage medium of claim 1, wherein the measure of respiratory ventilation is the product of a current half-breathing amplitude and a previous half-breathing amplitude.

5. The computer-readable storage medium of claim 4, wherein: The amplitude of the half breath is the tidal volume of the half breath.

6. The computer-readable storage medium of claim 1, wherein the processing comprises: If the duration of the event interval is outside the range of a typical periodic breathing cycle, or the number of non-zero measurements contained in the respiration and ventilation measurement sequence is less than the minimum number of non-zero respiration and ventilation measurements, it is determined that the event interval is likely not a periodic breathing cycle.

7. The computer-readable storage medium of claim 6, wherein the processing further comprises calculating a relative maximum phase feature from the sequence of respiration and ventilation measurements.

8. The computer-readable storage medium of claim 7, wherein the processing further comprises, if the event interval ends due to a hypopnea event: constructing a template representing an expected sequence of respiratory ventilation measurements consistent with said event intervals leading to periodic hypopnea; calculating a difference between the respiratory ventilation measurement sequence and the template; and The characteristic of the event interval is determined based on the relative maximum phase characteristic and the difference.

9. The computer-readable storage medium of claim 8, wherein the determining comprises: If the relative maximum phase feature exceeds a first threshold, determining that the event interval is likely not a periodic breathing cycle; and If the difference is smaller than a second threshold and the duration of the event interval is larger than a third threshold, it is determined that the event interval is likely to be a periodic breathing cycle.

10. The computer-readable storage medium of claim 7, wherein the processing further comprises, if the event interval ends due to an apnea event: constructing a template representing an expected sequence of respiratory ventilation measurements consistent with said event intervals leading to obstructive sleep apnea; constructing a template representing an expected sequence of respiratory ventilation measurements consistent with said event intervals leading to periodic apnea; calculating the difference between the respiratory ventilation measurement sequence and each template; calculating a periodic breathing similarity score from the difference; as well as The characteristic of the event interval is determined based on the relative maximum phase feature and the periodic breathing similarity score.

11. The computer-readable storage medium of claim 10, wherein: The determination includes: If the relative maximum phase feature exceeds a first threshold, determining that the event interval is likely not a periodic breathing cycle; and If the periodic breathing similarity score is greater than a second threshold and the duration of the event interval is greater than a third threshold, it is determined that the event interval is likely to be a periodic breathing cycle.

12. The computer-readable storage medium of any one of claims 1 to 11, wherein the determining comprises: calculating a count of event intervals in the history that are likely to be periodic breathing cycles, a count of event intervals in the history that are likely not periodic breathing cycles, and a total count of event intervals in the history; If the count meets the start criteria, changing the periodic breathing state to true; and If the count meets the end criteria, the periodic breathing state is changed to false.

13. The computer-readable storage medium of any one of claims 1 to 11, wherein the determining comprises: If the event interval ends due to timeout, the periodic breathing state is changed to false.

14. The computer-readable storage medium of claim 12, further comprising: When the periodic breathing state is changed to true, the start time of the just initiated periodic breathing event is adjusted.

15. The computer-readable storage medium of claim 12, further comprising: When the periodic breathing state is changed to false, the end time of the periodic breathing event that just ended is adjusted.

16. A device for detecting periodic breathing of a patient, the device comprising: a sensor configured to provide a signal representative of respiratory airflow of the patient; and A processor configured to detect periodic breathing of a patient, wherein the processor is configured to: receiving, using a signal from the sensor, a series of event intervals defined by apnea or hypopnea events detected in the respiration of the patient; At the end of an event interval, the event interval is processed to determine a characteristic of the event interval, wherein the characteristic of the event interval is determined using a set of characteristic descriptions including: (a) the event interval is determined to be likely to be a periodic respiratory cycle; (b) the event interval is determined to be unlikely to be a periodic respiratory cycle; and (c) if the event interval is determined to be neither (a) nor (b), the event interval is determined to be non-informative; and determining whether to change a current periodic breathing state indicating whether a periodic breathing event is ongoing based on a history of event interval characteristics that are longer than a typical length of a periodic breathing cycle, Therein, the process of determining the characteristic of the event interval depends on a sequence of respiratory ventilation measurements associated with the event interval.

17. The apparatus according to claim 16, further comprising: A therapeutic device configured to provide a patient with a respiratory disorder. Wherein the processor is further configured to adjust one or more parameters of the therapy in response to the detected periodic respiratory events.

18. The device according to any one of claims 16 and 17, further comprising a data communication interface coupled to the processor, wherein the processor is further configured to report the parameters of the detected periodic respiratory events to an external device through the data communication interface.

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