# US 11,298,074 B2 · Flow-based sleep stage determination > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,298,074 B2 - Document ID: US11298074B2 - Status: Granted - Kind: B2 - Application number: 15/373,344 - Filed: 2016-12-08 - Published: 2017-07-13 - Granted: 2022-04-12 - Earliest claimed: 2015-12-08 - Assignees: Fisher & Paykel Healthcare Limited - Applicants: Fisher & Paykel Healthcare Limited - Inventors: Simei Gomes Wysoski; David Robin Whiting - Web page: https://patentgrep.com/patent/US11298074B2 ## CPC - A61B 5/4815: {Sleep quality} - A61B 5/087: Measuring breath flow - A61B 5/4809: {Sleep detection, i.e. determining whether a subject is asleep or not} - A61B 5/4812: {Detecting sleep stages or cycles} - A61B 5/7225: {Details of analogue processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation (input circuits for detecting, measuring, or recording bioelectric or biomagnetic signals A61B5/30; specific diagnostic methods using bioelectric or biomagnetic signals A61B5/316)} - A61B 5/7239: {using differentiation including higher order derivatives} - A61B 5/7278: {Artificial waveform generation or derivation, e.g. synthesizing signals from measured signals} - A61B 5/742: {using visual displays (displays for heart-related electrical signals, e.g. ECG, A61B5/339)} - A61B 5/7475: {User input or interface means, e.g. keyboard, pointing device, joystick} - A61M 16/024: {including calculation means, e.g. using a processor} - G16H 50/30: for calculating health indices; for individual health risk assessment - A61M 16/16: Devices to humidify the respiration air {(A61M16/1045 takes precedence)} - A61M 2205/502: User interfaces, e.g. screens or keyboards - A61M 2230/40: Respiratory characteristics - G06N 20/00: Machine learning - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - A61M: DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY (introducing media into or onto the bodies of animals A61D7/00; means for inserting tampons A61F13/26; devices for administering food or medicines orally A61J; containers for collecting, storing or administering blood or medical fluids A61J1/05); DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY (surgery A61B; chemical aspects of surgical articles A61L); DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR {(Electrotherapy, e.g. producing anaesthesia by the use of alternating or intermittent currents A61N1/36021)} - G16H: HEALTHCARE INFORMATICS, i.e. INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR THE HANDLING OR PROCESSING OF MEDICAL OR HEALTHCARE DATA - G06N: COMPUTING ARRANGEMENTS BASED ON SPECIFIC COMPUTATIONAL MODELS ## Abstract A method and system of determining a sleep stage of a user involves receiving a respiratory flow signal of a user, obtaining at least one respiratory feature from at least part of the respiratory flow signal, and determining a sleep stage from the at least one respiratory feature. ## Claims ### Claim 1 A method of automatically determining a sleep stage of a user using a respiratory system configured to provide respiratory therapy to the user, the method comprising: using a controller of the respiratory system and one or more sensors of the respiratory system: receiving a respiratory flow signal of the user from the one or more sensors; obtaining at least one centre of mass measurement from the respiratory flow signal; automatically determining the sleep stage of the user from the at least one centre of mass measurement; and using the determined sleep stage of the user to adjust an operational parameter of the respiratory therapy. ### Claim 2 (depends on 1) The method of claim 1 further comprising obtaining at least one duration measurement from the respiratory flow signal, wherein automatically determining the sleep stage of the user further comprises automatically determining the sleep stage of the user from the at least one duration measurement. ### Claim 3 (depends on 2) The method of claim 2 wherein the at least one duration measurement includes one or more of breath duration, inspiration duration, maximum inspiration time, maximum expiration time, a function of maximum expiration time and maximum inspiration time, or a function of inspiration duration and breath duration. ### Claim 4 (depends on 1) The method of claim 1 further comprising obtaining at least one amplitude measurement from the respiratory flow signal, wherein automatically determining the sleep stage of the user further comprises automatically determining the sleep stage of the user from the at least one amplitude measurement. ### Claim 5 (depends on 4) The method of claim 4 wherein the at least one amplitude measurement includes one or more of maximum inspiration amplitude, maximum expiration amplitude, or a function of maximum inspiration amplitude and maximum expiration amplitude. ### Claim 6 (depends on 1) The method of claim 1 wherein the at least one centre of mass measurement includes one or both of: a function with variables including expiration centre of mass time and inspiration centre of mass time; or a function with variables including expiration centre of mass amplitude and inspiration centre of mass amplitude. ### Claim 7 (depends on 1) The method of claim 1 further comprising obtaining at least one derivative related measurement from the respiratory flow signal, wherein automatically determining the sleep stage of the user further comprises automatically determining the sleep stage of the user from the at least one derivative related measurement. ### Claim 8 (depends on 7) The method of claim 7 wherein the at least one derivative related measurement includes one or more of maximum negative acceleration time, maximum negative acceleration amplitude, maximum positive acceleration time, maximum positive acceleration amplitude, maximum negative flow rate time, maximum negative flow rate amplitude, maximum inspiration acceleration time, or maximum inspiration acceleration amplitude. ### Claim 9 (depends on 1) The method of claim 1 further comprising obtaining at least one volume related measurement from the respiratory flow signal, wherein automatically determining the sleep stage of the user further comprises automatically determining the sleep stage of the user from the at least one volume related measurement. ### Claim 10 (depends on 9) The method of claim 9 wherein the at least one volume related measurement includes one or more of inspiration volume, expiration volume, or a function of inspiration volume and expiration volume. ### Claim 11 (depends on 1) The method of claim 1 further comprising: identifying, within the respiratory flow signal, at least one breath signal representing a breath of the user; and obtaining at least one breath measurement from a portion of the respiratory flow signal within which the at least one breath signal is identified. ### Claim 12 (depends on 11) The method of claim 11 further comprising: identifying, within the respiratory flow signal, a window containing a plurality of breath signals; and obtaining respective breath measurements of the breath signals within the window. ### Claim 13 (depends on 12) The method of claim 12 wherein automatically determining the sleep stage of the user further comprises automatically determining the sleep stage of the user from at least one of a mean or a standard deviation of the breath measurements within at least part of the window. ### Claim 14 (depends on 1) The method of claim 1 further comprising determining the sleep stage from the at least one centre of mass measurement at least partly by applying at least one of a supervised learning algorithm, an unsupervised learning algorithm, or a semi-supervised learning algorithm. ### Claim 15 (depends on 1) The method of claim 1 wherein the sleep stage is one of a plurality of sleep stages configured to be determined by the method, the plurality of sleep stages comprising: awake, N1, N2, N3, and REM; awake, light sleep, deep sleep, and REM; awake, non-REM, and REM; or awake and asleep. ### Claim 16 (depends on 1) The method of claim 1 wherein the at least one centre of mass measurement includes: one or both of inspiration centre of mass time or mass amplitude; and one or both of expiration centre of mass time or mass amplitude. ### Claim 17 (depends on 1) The method of claim 1 wherein using the determined sleep stage of the user to adjust an operational parameter of the respiratory therapy comprises outputting control signals to adjust power to an air supply of the respiratory system based at least in part on the automatically determined sleep stage of the user. ### Claim 18 A respiratory system configured to provide respiratory therapy to a user and automatically determine a sleep stage of the user, the system comprising: a controller in electrical communication with one or more sensors located at the respiratory system and configured to receive a respiratory flow signal of the user from the one or more sensors, the controller comprising: a feature extractor configured to obtain at least one centre of mass measurement from at least part of the respiratory flow signal of the user; and a mapping module configured to automatically determine the sleep stage of the user from the at least one centre of mass measurement, wherein the controller is further configured to use the determined sleep stage of the user to adjust an operational parameter of the respiratory therapy. ### Claim 19 A respiratory system configured to provide respiratory therapy to a user and automatically determine a sleep stage of the user, the system comprising: a processor in electrical communication with one or more sensors located at the respiratory system; and a computer readable medium having stored thereon computer executable instructions that, when executed by the processor, cause the processor to perform a method of determining the sleep stage of the user, the method comprising: receiving a respiratory flow signal of the user from the one or more sensors; obtaining at least one centre of mass measurement from at least part of the respiratory flow signal; automatically determining the sleep stage of the user from the at least one centre of mass measurement; and using the determined sleep stage of the user to adjust an operational parameter of the respiratory therapy. ### Claim 20 A computer readable medium of a respiratory system configured to provide respiratory therapy to a user, the medium having stored thereon computer-executable instructions that, when executed by a processor of the respiratory system that is in electrical communication with one or more sensors located at the respiratory system, cause the processor to perform a method of automatically determining a sleep stage of a user, the method comprising: receiving a respiratory flow signal of the user from the one or more sensors; obtaining at least one centre of mass measurement from at least part of the respiratory flow signal; automatically determining the sleep stage of the user from the at least one centre of mass measurement; and using the determined sleep stage of the user to adjust an operational parameter of the respiratory therapy.