Auto CPAP system profile information

• US 20030213488A1
• Filed: 03/12/2003
• Published: 11/20/2003
• Est. Priority Date: 11/14/1991
• Status: Active Grant

• Current Assignee: John Edward Remmers, Thomas Richard Feroah
• Original Assignee: John Edward Remmers, Thomas Richard Feroah
• Inventors: Feroah, Thomas Richard, Remmers, John Edward
• Granted Patent: US 6,920,877 B2
• Time in Patent Office: Days
• US Class Current: 128/204.18
• CPC Class Codes: A61M 16/026 specially adapted for predicting, e.g. for determining an information representative of a flow limitation during a ventilation cycle by using a root square technique or a regression analysis
• CPC Class Codes: A61M 2016/0027 pressure meter
• CPC Class Codes: A61M 2016/0036 in the breathing tube and used in both inspiratory and expiratory phase
• CPC Class Codes: A61M 2205/3553 remote, e.g. between patient's home and doctor's office
• CPC Class Codes: A61M 2205/3561 local, e.g. within room or hospital

Abstract

The present invention relates to systems and methods for automatically and continuously regulating the level of nasal pressure to an optimal value during OSA treatment. OSA therapy is implemented by a device which automatically re-evaluates an applied pressure and continually searches for a minimum pressure required to adequately distend a patient'"'"'s pharyngeal airway. For example, this optimal level varies with body position and stage of sleep throughout the night. In addition, this level varies depending upon the patient'"'"'s body weight and whether or not alcohol or sleeping medicine has been ingested.

Claims

1. Method for adaptively providing continuous positive airway pressure in an upper airway system comprising the steps of:

detecting airflow in the upper airway system in predetermined increments of time;

averaging said airflow information over a second period of time;

distinguishing respiratory and non-respiratory components of said airflow using said averaged information;

identifying periods of inspiration and expiration using said non-respiratory flow information;

extracting features of said upper airway system during at least one of said periods of inspiration;

identifying airflow profiles based on said detected airflow and said extracted features;

determining a critical pressure which produces a first predetermined airflow profile;

introducing incremental pressure increases to determine a second pressure, greater than said first critical pressure, which produces a second predetermined airflow profile; and

setting pressure in said upper airway system using said second pressure.

2. Method according to claim 1, wherein said step of extracting further includes a step of:

determining an inspiratory airflow profile for said at least one period of inspiration.

3. Method according to claim 2, wherein said step of determining an inspiratory airflow profile further includes the step of:

calculating a roundness feature and a flatness feature for said at least one period of inspiration.

4. Method according to claim 3, wherein said step of determining further includes the steps of:

establishing a predetermined airflow limit from at least said roundness feature, said flatness feature and a peak airflow signal, said predetermined airflow limit being adjusted in accordance with predetermined limit modifiers.

5. Method according to claim 4, further comprising the step of:

updating said predetermined airflow limit modifiers in response to patient sleep stage and detected respiratory instabilities.

6. Method according to claim 1, further comprising the step of:

identifying test periods suitable for adjusting said upper airway pressure, said step of identifying test periods further including the step of detecting respiratory instabilities which would render said test periods inaccurate.

7. Method according to claim 6, wherein said step of identifying test periods further includes the step of:

initiating a test period when respiratory instabilities have been detected for a predetermined number of inspiration and expiration periods.

8. Method according to claim 6, wherein said step of detecting respiratory instabilities further includes the step of:

determining that predetermined upper airway system performance indices are within predetermined physiological ranges.

9. Method according to claim 8, wherein said step of determining further includes the step of:

detecting respiratory variation, apnea and hypoventilation.

10. Method according to claim 1, wherein said step of determining the non-respiratory component further includes the step of:

detecting airflow leaks in an airflow path connected with said upper airway system.

11. Method according to claim 1, wherein said step of determining a critical pressure further includes the steps of:

reducing pressure in said upper airway system by a first predetermined amount; and

incrementally reducing pressure in said upper airway system by a second predetermined amount less than said first predetermined amount.

12. Method according to claim 1, further including the step of:

storing extracted features and incremental pressure adjustments in memory.

13. Method according to claim 4, wherein said first and second predetermined airflow profiles correspond to peak airflow limits when said roundness and flatness features have not changed by more than a predetermined amount.

14. Method according to claim 1 further comprising the step of:

incorporating an additional external input from an oxygen saturation monitor or a snoring monitor.

15. Method according to claim 1 further comprising the step of:

incorporating an additional external input from a monitor of pressure, sound, oxygen saturation or body position.

16. Method for adaptively providing continuous positive airway pressure in an upper airway system comprising the steps of:

detecting airflow in the upper airway system;

averaging said airflow information over a predetermined period of time;

determining respiratory and non-respiratory components of said airflow using said averaged information;

identifying periods of inspiration and expiration using said non-respiratory flow information; and

incrementally adjusting pressure in said upper airway system in response to airflow information detected during said period of inspiration.

17. Method according to claim 16, wherein said step of adjusting further includes steps of:

identifying a critical pressure at which a significant obstruction occurs during said inspiration; and

identifying an optimum pressure for eliminating said obstruction during said inspiration.

18. Method according to claim 16, wherein said step of adjusting is performed by identifying relative changes in airflow during said step of detecting.

19. Method according to claim 16, wherein said step of adjusting further includes steps of:

extracting features indicative of airflow resistance in said upper airway system.

20. Method according to claim 17, wherein said step of identifying a critical pressure and an optimum pressure further includes the step of:

introducing incremental pressure perturbations into said upper airway system;

extracting characteristic features of said upper airway system during inspiration;

using said extracted characteristics to identify the optimum pressure and the critical pressure.

21. System for providing continuous positive airway pressure in an upper airway system comprising:

means for detecting airflow in an upper airway system of a patient;

means for generating pressure in said upper airway system in response to a command pressure; and

means for adaptively controlling said pressure generating means in response to said detecting means to automatically provide continuous positive airway pressure, said adaptive control means introducing incremental pressure perturbations for setting a command pressure relative to a predetermined critical pressure.

22. System according to claim 21, wherein said adaptive control means further includes:

means for averaging airflow information over a predetermined period of time and for determining non-respiratory flow using said averaged information; and

means for identifying periods of inspiration and expiration using said non-respiratory flow information.

23. System according to claim 22, wherein said adaptive control means identifies said critical pressure as a pressure at which a predetermined upper airway obstruction occurs during said inspiration.

24. System according to claim 23, wherein said adaptive control means extracts features indicative of airflow resistance in said upper airway system to identify said critical pressure and to set said command pressure.

25. System according to claim 24, wherein said extracted features include flatness, roundness and peak flow.

26. System according to claim 21 wherein said adaptive control means further includes:

means for incorporating an additional external input from an oxygen saturation monitor or a snoring monitor.

27. System according to claim 21 wherein said adaptive control means further includes:

means for incorporating an additional external input from a monitor of pressure, sound, oxygen saturation or body position.