US-12616812-B2 - Methods and apparatus for treating respiratory disorders

Abstract

Methods and apparatus infer or indicate sleep stage(s) of a patient from a respiratory flow rate signal of the patient. The method may include applying a plurality of detection pathways to a signal representing a respiratory flow rate of the patient, wherein each detection pathway is configured to generate start events and end events indicating start times and end times of episodes respectively of a corresponding sleep stage, wherein each start event and each end event has a priority; and combining the start events and end events based on their priorities to produce an indication of the sleep stage of the patient. The apparatus may include a sensor configured to generate a signal representing a property of a flow of air within a patient interface; and a processor configured to implement a method of inferring a sleep stage of the patient from the signal.

Inventors

• Dinesh Ramanan

Assignees

• ResMed Pty Ltd

Dates

Publication Date

20260505

Application Date

20220728

Priority Date

20160202

Claims (20)

1. 1 . A method of indicating wakefulness of a patient, the method comprising: applying, in a wakefulness detector of one or more processors, first and second parallel detection pathways to breath features derived from a signal representing a respiratory flow rate of the patient; in each of the first and second parallel detection pathways, assessing the breath features, wherein the first parallel detection pathway is configured to evaluate variation of the breath features in a short term and wherein the second parallel detection pathway is configured to evaluate variation of the breath features in a long term; and generating, from the wakefulness detector of the one or more processors, start events and end events from the evaluations of the first parallel detection pathway and the second parallel detection pathway to produce indications of wakefulness of the patient.
2. 2 . The method of claim 1 , wherein the breath features comprise at least one of: (a) inter-breath intervals, (b) tidal volume, and (c) expiratory flow shape.
3. 3 . The method of claim 1 , wherein the produced indications of wakefulness comprise an indication of short-term awake from the first parallel detection pathway and an indication of long-term awake from the second parallel detection pathway.
4. 4 . The method of claim 3 , wherein the indication of long-term awake comprises generating indications of first and second types of long-term awake.
5. 5 . The method of claim 1 , wherein the first parallel detection pathway is a state machine having a plurality of states comprising: an initial state, a provisional short-term awake state, a provisional escape state and a confirmed short-term awake state.
6. 6 . The method of claim 1 , wherein the second parallel detection pathway is a state machine having a plurality of states comprising: an initial state, a provisional long-term awake state, a provisional back-to-sleep state, a confirmed back-to-sleep state and a confirmed long-term awake state.
7. 7 . The method of claim 1 , wherein the wakefulness detector generates a short-term awake start event on detecting large short-term variation in the breath features.
8. 8 . The method of claim 1 , wherein the wakefulness detector generates a long-term awake start event on detecting large long-term variation in the breath features.
9. 9 . The method of claim 8 , wherein the wakefulness detector generates a long-term awake start event of a second type on detecting medium-term variability of a breath feature.
10. 10 . A computer processor-readable memory storage apparatus having processor-executable instructions encoded thereon which, when executed by one or more processors, control the one or more processors to perform a method of indicating wakefulness of a patient, the processor-executable instructions comprising: instructions to apply, in a wakefulness detector of one or more processors, first and second parallel detection pathways to breath features derived from a signal representing a respiratory flow rate of the patient; instructions to assess, in each of the first and second parallel detection pathways, the breath features, wherein the first parallel detection pathway is configured to evaluate variation of the breath features in a short term and wherein the second parallel detection pathway is configured to evaluate variation of the breath features in a long term; and instructions to generate, from the wakefulness detector of the one or more processors, start events and end events from the evaluations of the first parallel detection pathway and the second parallel detection pathway to produce indications of wakefulness of the patient.
11. 11 . The computer processor-readable memory storage apparatus of claim 10 , wherein the breath features comprise at least one of: (a) inter-breath intervals, (b) tidal volume, and (c) expiratory flow shape.
12. 12 . The computer processor-readable memory storage apparatus of claim 10 , wherein the produced indications of wakefulness comprise an indication of short-term awake from the first parallel detection pathway and an indication of long-term awake from the second parallel detection pathway.
13. 13 . The computer processor-readable memory storage apparatus of claim 12 , wherein the indication of long-term awake comprises generating indications of first and second types of long-term awake.
14. 14 . The computer processor-readable memory storage apparatus of claim 10 , wherein the first parallel detection pathway is a state machine having a plurality of states comprising: an initial state, a provisional short-term awake state, a provisional escape state and a confirmed short-term awake state.
15. 15 . The computer processor-readable memory storage apparatus of claim 10 , wherein the second parallel detection pathway is a state machine having a plurality of states comprising: an initial state, a provisional long-term awake state, a provisional back-to-sleep state, a confirmed back-to-sleep state and a confirmed long-term awake state.
16. 16 . The computer processor-readable memory storage apparatus of claim 10 , wherein the wakefulness detector generates a short-term awake start event on detecting large short-term variation in the breath features.
17. 17 . The computer processor-readable memory storage apparatus of claim 10 , wherein the wakefulness detector generates a long-term awake start event on detecting large long-term variation in the breath features.
18. 18 . The computer processor-readable memory storage apparatus of claim 17 , wherein the wakefulness detector generates a long-term awake start event of a second type on detecting medium-term variability of a breath feature.
19. 19 . An apparatus comprising: a sensor configured to generate a signal representing a property of a flow of air within a patient interface configured to engage with an entrance to an airway of a patient; and one or more processors configured to receive the signal and further configured to: apply, in a wakefulness detector of one or more processors, first and second parallel detection pathways to breath features derived from the signal; in each of the first and second parallel detection pathways, assess the breath features, wherein the first parallel detection pathway is configured to evaluate variation of the breath features in a short term and wherein the second parallel detection pathway is configured to evaluate variation of the breath features in a long term; and generate, from the wakefulness detector of the one or more processors, start events and end events from the evaluations of the first parallel detection pathway and the second parallel detection pathway to produce indications of wakefulness of the patient.
20. 20 . The apparatus of claim 19 , further comprising: a pressure generator configured to generate a supply of air at positive pressure to an airway of the patient via the patient interface over an air circuit, wherein the one or more processors is/are configured to control the supply of air based on the wakefulness indicated.

Description

1 CROSS-REFERENCE TO RELATED APPLICATIONS The present application is a continuation application of U.S. patent application Ser. No. 16/071,334, filed Jul. 19, 2018, which is a national phase entry under 35 U.S.C. § 371 of International Application No. PCT/AU2017/050081 filed Feb. 1, 2017, published in English, which claims priority from Australian Provisional Patent Application No. AU 2016900329, filed Feb. 2, 2016, all of which are incorporated herein by reference. A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in Patent Office patent files or records, but otherwise reserves all copyright rights whatsoever. BACKGROUND OF THE TECHNOLOGY 2.1 Field of the Technology The present technology relates to one or more of the detection, diagnosis, treatment, prevention and amelioration of respiratory-related disorders. The present technology also relates to medical devices or apparatus, and their use. 2.2 Description of the Related Art 2.2.1 Human Respiratory System and its Disorders The respiratory system of the body facilitates gas exchange. The nose and mouth form the entrance to the airways of a patient. The airways include a series of branching tubes, which become narrower, shorter and more numerous as they penetrate deeper into the lung. The prime function of the lung is gas exchange, allowing oxygen to move from the air into the venous blood and carbon dioxide to move out. The trachea divides into right and left main bronchi, which further divide eventually into terminal bronchioles. The bronchi make up the conducting airways, and do not take part in gas exchange. Further divisions of the airways lead to the respiratory bronchioles, and eventually to the alveoli. The alveolated region of the lung is where the gas exchange takes place, and is referred to as the respiratory zone. See “Respiratory Physiology”, by John B. West, Lippincott Williams & Wilkins, 9th edition published 2011. A range of respiratory disorders exist. Certain disorders may be characterised by particular events, e.g. apneas, hypopneas, and hyperpneas. Obstructive Sleep Apnea (OSA), a form of Sleep Disordered Breathing (SDB), is characterized by events including occlusion or obstruction of the upper air passage during sleep. It results from a combination of an abnormally small upper airway and the normal loss of muscle tone in the region of the tongue, soft palate and posterior oropharyngeal wall during sleep. The condition causes the affected patient to stop breathing for periods typically of 30 to 120 seconds in duration, sometimes 200 to 300 times per night. It often causes excessive daytime somnolence, and it may cause cardiovascular disease and brain damage. The syndrome is a common disorder, particularly in middle aged overweight males, although a person affected may have no awareness of the problem. See U.S. Pat. No. 4,944,310 (Sullivan). A range of therapies have been used to treat or ameliorate such conditions. Furthermore, otherwise healthy individuals may take advantage of such therapies to prevent respiratory disorders from arising. However, these have a number of shortcomings. 2.2.2 Therapy Continuous Positive Airway Pressure (CPAP) therapy has been used to treat Obstructive Sleep Apnea (OSA). The mechanism of action is that continuous positive airway pressure acts as a pneumatic splint and may prevent upper airway occlusion, such as by pushing the soft palate and tongue forward and away from the posterior oropharyngeal wall. Treatment of OSA by CPAP therapy may be voluntary, and hence patients may elect not to comply with therapy if they find devices used to provide such therapy one or more of: uncomfortable, difficult to use, expensive and aesthetically unappealing. 2.2.3 Treatment Systems These therapies may be provided by a treatment system or device. Such systems and devices may also be used to diagnose a condition without treating it. A treatment system may comprise a Respiratory Pressure Therapy Device (RPT device), an air circuit, a humidifier, a patient interface, and data management. 2.2.3.1 Patient Interface A patient interface may be used to interface respiratory equipment to its wearer, for example by providing a flow of air to an entrance to the airways. The flow of air may be provided via a mask to the nose and/or mouth, a tube to the mouth or a tracheostomy tube to the trachea of a patient. Depending upon the therapy to be applied, the patient interface may form a seal, e.g., with a region of the patient's face, to facilitate the delivery of air at a pressure at sufficient variance with ambient pressure to effect therapy, e.g., at a positive pressure of about 10 cmH2O relative to ambient pressure. For other forms of therapy, such as the delivery of oxygen, the patient interface may not include a seal sufficient t