Characterising systems for respiratory therapy

Patent metadata

Field	Value
Publication number	US-2024424236-A1
Application number	US-202218695236-A
Country	US
Kind code	A1
Filing date	Sep 28, 2022
Priority date	Sep 29, 2021
Publication date	Dec 26, 2024
Grant date	—

Abstract

Apparatus and methods provide system characterisation such as for operation of respiratory treatment apparatus. Pressure and the flow rate signals from a therapy session may be analysed to determine a curve representing a pressure and flow characteristic of the system, such as where the system includes a delivery conduit and a patient interface with a vent. A pressure drop parameter may be derived such that the parameter is characteristic of pressure drop from a sensor in a therapy generator to the patient interface based on a first function characterizing the curve and a second function characterizing a curve representing a pressure and flow characteristic of a component of the system. The parameter may be derived from a difference between the first function and a second function. Signal(s) may be generated for controlling the therapy generator to adjust a property of supplied flow of air based on the pressure drop parameter.

First claim

1 . Apparatus for respiratory therapy, the apparatus comprising:
a pressure generator configured to generate a flow of air for delivery to a patient interface via a delivery conduit for a respiratory therapy for a patient, the patient interface comprising a vent; a pressure transducer configured to generate a signal representing a pressure generated by the pressure generator; a flow rate transducer configured to generate a signal representing a flow rate of the flow of air a controller configured to:
receive the pressure signal and the flow rate signal from the transducers;
analyse the pressure signal and the flow rate signal to determine a system curve representing a pressure and flow characteristic of a respiratory therapy system comprising the apparatus, the delivery conduit and the patient interface;
access data associated with a component curve representing a pressure and flow characteristic of at least one component of the system;
derive a pressure drop parameter that is characteristic of pressure drop across the vent of the patient interface and/or a pressure drop up to the patient interface, based on a first function characterising the system curve and a second function representing the component curve; and
based on the derived pressure drop parameter, effect an output.

2 . The apparatus of claim 1 wherein the output includes at least one of:
saving data indicative of the derived pressure drop parameter to a storage device of a remote server;
generating one or more signals to control operation of the pressure generator to adjust a property of the flow of air based on the pressure drop parameter;
displaying information indicative of the derived pressure drop parameter on a display of the apparatus for respiratory therapy; and
transmitting information indicative of the derived pressure drop parameter to a remote server.

3 . The apparatus of claim 1 , wherein the second function characterises a component curve representing a pressure and flow characteristic of a vent of the patient interface.

4 . The apparatus of claim 1 , wherein the first function is a quadratic function.

5 . The apparatus of claim 4 wherein the first function comprises a lookup table relating pressure values and flow rate values.

6 . The apparatus of claim 3 , wherein the second function comprises a quadratic function.

7 . The apparatus of claim 3 , wherein wherein the second function comprises a lookup table relating pressure values and flow rate values.

8 . The apparatus of claim 1 , wherein to derive the pressure drop parameter, the controller is configured to determine a difference with the first function and the second function.

9 . The apparatus of claim 8 , wherein the difference comprises a difference between a first reference pressure drop parameter that is characteristic of pressure drop from the pressure generator to atmosphere via the system and a second reference pressure drop parameter that is characteristic of pressure drop across the vent to atmosphere.

10 . The apparatus of claim 9 , wherein the controller is configured to determine the first reference pressure drop parameter by applying a measure of flow rate from the flow transducer to the first function.

11 . The apparatus of claim 9 , wherein the controller is configured to determine the second reference pressure drop parameter by applying a measure of flow rate from the flow transducer to the second function.

12 . The apparatus of claim 11 , wherein the controller is configured to subtract the second reference pressure drop parameter from the first reference pressure drop parameter to derive the pressure drop parameter that is characteristic of pressure drop from the pressure generator to the patient interface.

13 . The apparatus of claim claim 2 , wherein the controller is configured to generate the one or more signals for controlling operation of the pressure generator to control pressure in the patient interface by:
adding the derived pressure drop parameter that is characteristic of pressure drop from the pressure generator to the patient interface to a target therapy pressure parameter and (a) compare a result of the addition to a measure of the device pressure from the pressure transducer and control one or more of the blower driving parameters based on the comparison; or (b) using the result of the addition to control one or more of the blower driving parameters; subtracting the derived pressure drop parameter that is characteristic of pressure drop from the pressure generator to the patient interface from a target therapy pressure parameter and comparing a result of the subtracting to a measure of pressure from the pressure transducer; or adding the derived pressure drop parameter that is characteristic of pressure drop from the pressure generator to the patient interface to a measure of pressure from the pressure transducer, and comparing a result of the adding to the target therapy pressure parameter.

14 . The apparatus of claim 13 , wherein the controller is configured to detect one or more events of sleep disordered breathing by evaluating one or more of the signals received from the pressure transducer and/or the flow rate transducer, and to modify the target therapy pressure parameter based on the evaluating.

15 . The apparatus of claim 14 , wherein the one or more events comprises an event from the group consisting of: an apnea, a hypopnea, a snore, and inspiratory flow limitation.

16 . The apparatus of claim 1 , wherein the controller is configured to determine an actual pressure in the patient interface by subtracting: (a) the derived pressure drop parameter that is characteristic of pressure drop from the pressure generator to the patient interface, from (b) a measure of pressure determined from the signal received from the pressure transducer.

17 . The apparatus of claim 1 , wherein the analyse of the pressure signal and the flow rate signal to determine the curve representing a pressure and flow characteristic of a system selects values for the curve that correspond to therapy use when mask leak is effectively zero.

18 . The apparatus of claim 1 , wherein the analysis comprises a determination of parameters that best fit a template curve to a plurality of points, each point comprising: (a) a pressure value, and (b) a flow rate value at the pressure value.

19 . The apparatus of claim 1 , wherein the controller is a central controller of the pressure generator.

20 . The apparatus of claim 19 , wherein the central controller is configured to determine an identification of the patient interface based on the template curve.

21 . The apparatus of claim 1 , wherein the curve representing the pressure and flow characteristic of the system comprises:
(a) pressure values comprising values of a low-pass filtered version of measured pressure from the pressure signal; and (b) flow rate values comprising values of a low-pass filtered version of measured flow rate from the flow rate signal at the pressure value.

22 . The apparatus of claim 1 , wherein the controller is configured to, for the analysis, use the pressure signal and the flow rate signal that are generated by the pressure transducer and flow rate transducer during a therapy session comprising automatic positive airway pressure (APAP) therapy.

23 . A method of operating in a respiratory treatment apparatus comprising a pressure generator configured to generate a flow of air for delivery to a patient

Assignees

• ResMed Pty Ltd

Inventors

• Holley Liam

Classifications

• A61M2230/42

  Rate · CPC title

• A61M2205/3553

  remote, e.g. between patient's home and doctor's office · CPC title

• A61M2016/003

  with a flowmeter · CPC title

• A61M2016/0027

  pressure meter · CPC title

• A61M16/0616

  with face sealing means comprising a flap or membrane projecting inwards, such that sealing increases with increasing inhalation gas pressure · CPC title