Distinguishing between closed and open airway apneas and treating patients accordingly

• US 8,752,547 B2
• Filed: 12/20/2012
• Issued: 06/17/2014
• Est. Priority Date: 11/05/1993
• Status: Expired due to Fees

• Current Assignee: Resmed Limited (ResMed Incorporated)
• Original Assignee: Resmed Limited (ResMed Incorporated)
• Inventors: Berthon-Jones, Michael
• Primary Examiner(s): MATTER, KRISTEN CLARETTE
• Application Number:
  US13/722,111
• Publication Number:
  US 20130174847A1
• Time in Patent Office: 544 Days
• Field of Search: 128/203.23, 128/203.21, 128/204.18, 12820421-20423, 128/205.11, 128/205.23, 600/484, 600/481, 600/529, 600/533, 600/538
• US Class Current: 128/204.21
• CPC Class Codes: A61B 5/087 Measuring breath flow
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: A61F 5/56 Devices for preventing snoring by influencing the respiratory system by gas treatment A61M16/00
• CPC Class Codes: A61M 16/0006 with means for creating vibrations in patients' airways
• CPC Class Codes: A61M 16/0066 Blowers or centrifugal pumps
• CPC Class Codes: A61M 16/0069 the speed thereof being controlled by respiratory parameters, e.g. by inhalation
• CPC Class Codes: A61M 16/024 including calculation means, e.g. using a processor
• CPC Class Codes: A61M 16/06 Respiratory or anaesthetic masks
• CPC Class Codes: A61M 16/0875 Connecting tubes
• CPC Class Codes: A61M 2016/0039 in the inspiratory circuit
• CPC Class Codes: A61M 2230/60 Muscle strain, i.e. measured on the user

Abstract

A method of controlling treatment of respiratory conditions of a patient includes determining a signal representative of patient respiratory flow. The signal is analyzed to determine (i) the presence of an apnea and a hypopnea and (ii) if present, a type of the apnea or hypopnea. A motor driven blower is controlled to increase a treatment pressure of an airflow delivered toward the airway of the patient upon determination of the presence of an apnea or a hypopnea depending on the type of the apnea or hypopnea, and otherwise to decrease the treatment pressure.

Claims

1. A method of controlling treatment of respiratory conditions of a patient, the method comprising:

determining a signal representative of patient respiratory flow;

analyzing the signal to determine (i) the presence of an apnea and a hypopnea and (ii) if present, a type of the apnea or hypopnea; and

controlling a motor driven blower to increase a treatment pressure of an airflow delivered toward the airway of the patient upon determination of the presence of an apnea or a hypopnea depending on the type of the apnea or hypopnea being obstructive, and otherwise to decrease the treatment pressure for inspiration upon determination of the presence of an apnea or a hypopnea depending on the type of the apnea or hypopnea being central.

2. The method of claim 1, wherein the controlling comprises setting the motor driven blower to increase the treatment pressure upon determination of the presence of an obstructive apnea or an obstructive hypopnea.

3. The method of claim 2, further comprising calculating a patency index of the signal to determine the presence of an obstructive apnea or an obstructive hypopnea.

4. The method of claim 3, wherein the calculating comprises detecting cardiogenic airflow in the signal during the apnea or hypopnea.

5. The method of claim 3, wherein the calculating comprises evaluating an induced oscillatory airflow in the signal during the apnea or hypopnea.

6. The method of claim 3, further comprising adjusting the patency index to compensate for a leak in the airflow delivered toward the patient.

7. The method of claim 1, further comprising calculating a variance of the signal to determine the presence of an apnea and a hypopnea.

8. The method of claim 7, wherein the calculating comprises computing a moving average variance of the signal.

9. The method of claim 1, wherein analyzing the signal further comprises determining the presence of a flow limitation.

10. The method of claim 9, wherein the determination of the presence of a flow limitation comprises calculating an obstruction index of the signal.

11. The method of claim 10, wherein the controlling comprises setting the motor driven blower to increase the treatment pressure as a function of the calculated obstruction index upon determination of the presence of a flow limitation.

12. The method of claim 10, wherein the obstruction index is calculated with a shape factor determined from a scaled inspiratory portion of the signal.

13. The method of claim 12, further comprising calculating the shape factor by operating on a mid-portion of the scaled inspiratory portion of the signal.

14. The method of claim 10, wherein the obstruction index comprises a calculated snore signal derived from the signal.

15. An apparatus for treating respiratory conditions of a patient comprising:

a sensor for determining a signal representative of patient respiratory flow;

a processor coupled to the sensor for analyzing the signal to determine (i) the presence of an apnea and a hypopnea and (ii) if present, a type of the apnea or hypopnea; and

a motor driven blower for increasing a treatment pressure of an airflow delivered toward the airway of the patient upon determination of the presence of an apnea or a hypopnea depending on the type of the apnea or hypopnea being obstructive, and otherwise for decreasing the treatment pressure for inspiration upon determination of the presence of an apnea or a hypopnea depending on the type of the apnea or hypopnea being central.

16. The apparatus of claim 15, wherein the processor is configured to set the motor driven blower to increase the treatment pressure upon determination of the presence of an obstructive apnea or an obstructive hypopnea.

17. The apparatus of claim 16, wherein the processor is configured to calculate a patency index of the signal to determine the presence of an obstructive apnea or an obstructive hypopnea.

18. The apparatus of claim 17, wherein the processor is configured to detect cardiogenic airflow in the signal during the apnea or hypopnea.

19. The apparatus of claim 17, wherein the processor is configured to evaluate an induced oscillatory airflow in the signal during the apnea or hypopnea.

20. The apparatus of claim 17, wherein the processor is configured to adjust the patency index to compensate for a leak in the airflow delivered toward the patient.

21. The apparatus of claim 15, wherein the processor is configured to calculate a variance of the signal representative of patient respiratory flow to determine the presence of an apnea and a hypopnea.

22. The apparatus of claim 21, wherein the processor is configured to calculate the variance based on a moving average variance of the signal.

23. The apparatus of claim 15, wherein the processor is configured to determine the presence of a flow limitation.

24. The apparatus of claim 23, wherein the processor is configured to determinate the presence of a flow limitation by calculating an obstruction index of the signal.

25. The apparatus of claim 24, wherein the processor sets the motor driven blower to increase the treatment pressure as a function of the calculated obstruction index upon determination of the presence of a flow limitation.

26. The apparatus of claim 24, wherein the processor is configured to calculate the obstruction index by calculating a shape factor from a scaled inspiratory portion of the signal.

27. The apparatus of claim 26, wherein the processor is configured to calculate the shape factor by operating on a mid-portion of the scaled inspiratory portion of the signal.

28. The apparatus of claim 24, wherein the processor is configured to calculate the obstruction index by calculating a snore signal from the signal.

29. The apparatus of claim 15 wherein the sensor comprises a flow sensor.