Control of pressure for breathing comfort

Patent metadata

Field	Value
Publication number	US-11052206-B2
Application number	US-201314400817-A
Country	US
Kind code	B2
Filing date	May 13, 2013
Priority date	May 14, 2012
Publication date	Jul 6, 2021
Grant date	Jul 6, 2021

Abstract

A respiratory treatment apparatus generates an indication of inspiration or expiration based on a measure of motor current of a flow generator. In an example, first and second current signals are derived from the measurement. The first derived current signal may be a long term measure or average of current and the second derived current signal may be a short term measure or average of current. A processor ( 120 ) determines an indication of inspiration or expiration as a function of the first and second derived current signals. The function of the first derived current signal and the second derived current signal may be a comparison of the derived current signals. The derived signals may be determined by filtering. The indication of inspiration or expiration may serve as a trigger or cycle control for changing treatment pressure in synchrony with patient respiration without measured signals from pressure, flow or speed sensors.

First claim

The invention claimed is:

1. A method of a respiratory treatment apparatus for determining an indication of inspiration or expiration, the method comprising:
measuring current supplied to a blower configured to provide a respiratory treatment;
deriving first and second current signals from the measured current, the first derived current signal being a long term measure of current, the second derived current signal being a short term measure of current; and
determining with a processor an indication of inspiration or expiration by comparison of the first derived current signal and the second derived current signal, wherein the first derived current signal and the second derived current signal are each derived by filtering, the filtering consisting of low pass filtering the measured current.

2. The method of claim 1 wherein the comparison generates a control signal to set a speed change of a blower.

3. The method of claim 2 wherein the first derived current signal is derived by a low pass filter with a first time constant.

4. The method of claim 3 wherein the first time constant is on an order of a time period greater than an average breath.

5. The method of claim 2 wherein the second derived current signal is derived by a low pass filter with a second time constant.

6. The method of claim 5 wherein the second time constant is on an order of a time period shorter than an average breath.

7. The method of claim 1 wherein the comparison of the first derived current signal and the second derived current signal is performed by a comparator.

8. The method of claim 1 further comprising adding a compensation signal to the first derived current signal.

9. The method of claim 8 wherein the compensation signal is based on the indication of inspiration or expiration and compensates for delay in determining a phase change in a respiratory cycle.

10. The method of claim 9 wherein a negative compensation signal is added to the first derived current signal based on the indication of inspiration, and a positive compensation signal is added to the first derived current signal based on the indication of expiration.

11. The method of claim 8 wherein the comparison of the first derived current signal and the second derived current signal comprises a comparison of the second derived current signal and the sum of the first derived current signal and the compensation signal.

12. The method of claim 9 wherein the comparison generates a control signal to set a speed change of a blower.

13. The method of claim 1 further comprising maintaining the first derived current signal with blanking values rather than the measure of current during a transition of the indicator of inspiration of expiration.

14. The method of claim 1 further comprising, controlling with the processor setting of a pressure treatment generated by the blower based on the indication of inspiration or expiration.

15. A respiratory treatment apparatus for determining an indication of inspiration or expiration, the apparatus comprising:
a blower, including an impeller and motor, the blower configured to generate a pressure treatment to a patient interface;
a current sensing circuit configured to generate a current signal representative of current supplied to the motor; and
a processor coupled to the sensing circuit, the processor configured to: (a) derive first and second current signals from the current sensing circuit, the first derived current signal being a long term measure of current, the second derived current signal being a short term measure of current, and (b) determine an indication of inspiration or expiration by comparison of the first derived current signal and the second derived current signal, wherein the first derived current signal and the second derived current signal are each derived by filtering, the filtering consisting of low pass filtering the measured current.

16. The apparatus of claim 15 wherein the processor comprises a filter to generate the second derived current signal by filtering of the measured current.

17. The apparatus of claim 16 wherein the filter comprises a low pass filter with a first time constant.

18. The apparatus of claim 17 wherein the processor further comprises a further filter to generate the first derived current signal by filtering of the second derived current signal, the further filter comprising a low pass filter with a second time constant, wherein the first time constant is on an order of a time period shorter than an average breath and the second time constant is on an order of a time period greater than an average breath.

19. The apparatus of claim 16 further comprising a further filter to generate the first derived current signal by filtering of the second derived current signal or the measured current.

20. The apparatus of claim 15 wherein the comparison of the first derived current signal and the second derived current signal generates a control signal to set a speed change of a blower.

21. The apparatus of claim 15 wherein the processor is further configured to add a compensation signal to the first derived current signal.

22. The apparatus of claim 21 wherein the compensation signal is a function of the determined indication of inspiration or expiration and compensates for delay in determining a phase change in a respiratory cycle.

23. The apparatus of claim 22 wherein the processor is configured to add a negative compensation signal to the first derived current signal based on the determined indication of inspiration and to add a positive compensation signal to the first derived current signal based on the determined indication of expiration.

24. The apparatus of claim 22 wherein the comparison ( 1 ) compares the second derived current signal and the sum of the first derived current signal and the compensation signal, and (b) generates a control signal to set a speed change of a blower.

25. The apparatus of claim 21 wherein the comparison comprises a comparison of the second derived current signal and the sum of the first derived current signal and the compensation signal.

26. The apparatus of claim 15 wherein the processor is further configured to maintain the first derived current signal with blanking values rather than the measure of current during a transition associated with the determined indication of inspiration or expiration.

27. The apparatus of claim 15 wherein the processor is further configured to control setting of the pressure treatment generated by the blower based on the indication of inspiration or expiration.

28. A method of a respiratory treatment apparatus for determining an indication of inspiration or expiration, the method comprising:
measuring current supplied to a blower configured to provide a respiratory treatment;
deriving first and second current signals from the measured current, the first derived current signal being a long term measure of current, the second derived current signal being a short term measure of current; and
determining with a processor an indication of inspiration or expiration by comparison of the first derived current signal and the second derived current signal, wherein the first derived current signal and the second derived current signal are each derived by filtering, the filtering consisting of low pass filtering the measured current,
wherein a negative compensation signal is added t

Assignees

• Resmed Motor Technologies Inc

Inventors

• Fleming David James
• Grunberg Michael

Classifications

• A61B5/097

  Devices for facilitating collection of breath or for directing breath into or through measuring devices · CPC title

• A61M2016/0021

  with a proportional output signal, e.g. from a thermistor · CPC title

• A61M16/107

  in the inspiratory path · CPC title

• A61M16/0683

  Holding devices therefor · CPC title

• A61M2205/505

  Touch-screens; Virtual keyboard or keypads; Virtual buttons; Soft keys; Mouse touches · CPC title