Method and device for carrying out a signal-processing viewing of a measurement signal that is correlated to the respiratory activity of an individual

• US 7,722,546 B2
• Filed: 10/17/2003
• Issued: 05/25/2010
• Est. Priority Date: 10/17/2002
• Status: Active Grant

• Current Assignee: ResMed Humidification Technologies GmbH (ResMed Incorporated)
• Original Assignee: MAP Medizin-Technologie GMBH (ResMed Incorporated)
• Inventors: Madaus, Stefan, Heidmann, Dieter, Meier, Jorg, Schneider, Hartmut
• Primary Examiner(s): Mallari; Patricia C
• Assistant Examiner(s): Toth; Karen E
• Application Number:
  US10/531,476
• Publication Number:
  US 20060037614A1
• Time in Patent Office: 2,412 Days
• Field of Search: 600529-543, 128/204.23
• US Class Current: 600/538
• CPC Class Codes: A61B 5/085 Measuring impedance of respiratory organs or lung elasticity
• CPC Class Codes: A61B 5/087 Measuring breath flow
• CPC Class Codes: A61B 5/4836 Diagnosis combined with treatment in closed-loop systems or methods A61B5/0036 takes precedence
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61B 5/7275 Determining trends in physiological measurement data; Predicting development of a medical condition based on physiological measurements, e.g. determining a risk factor
• CPC Class Codes: A61B 5/7282 Event detection, e.g. detecting unique waveforms indicative of a medical condition A61B5/4094, A61B5/4818, A61B5/349, A61B5/0823 take precedence
• CPC Class Codes: A61F 5/56 Devices for preventing snoring by influencing the respiratory system by gas treatment A61M16/00
• CPC Class Codes: A61M 16/0003 Accessories therefor, e.g. sensors, vibrators, negative pressure
• 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 2016/0018 electrical
• CPC Class Codes: A61M 2016/0033 electrical
• CPC Class Codes: A61M 2016/0036 in the breathing tube and used in both inspiratory and expiratory phase
• CPC Class Codes: A61M 2230/005 Parameter used as control input for the apparatus

Abstract

The invention relates to a method and device for carrying out a signal-processing viewing of a measurement signal that is correlated with the respiratory activity of an individual, for example, of a measurement signal that is correlated with the respiratory gas. The aim of the invention is to provide solutions with which an improved electronic analysis of the signals that are representative with regard to respiratory activity can be achieved. To this end, the invention provides that viewing results are obtained within the scope of a signal-processing viewing of said measurement signal and make a differentiation between obstructive and central respiratory disorders possible. The viewing results are determined, in particular, while taking into account changes of selected breathing characteristics such as, for example, the change in the ratio of inhalation time to exhalation time.

Claims

1. A method of carrying out signal-processing consideration of a measurement signal related to the respiration activity of a person when matching pressure regulation in administering a breathable gas at a pressure level which at least in phase-wise manner is above ambient pressure, the method comprising:

differentiating the measurement signal on a positive airway pressure (PAP) device to generate evaluation results indicative of the respiratory gas flow, the differentiating permitting classification between obstructive and central breathing disorders,

wherein the differentiating alone permits classification between obstructive and central breathing disorders.

2. A method as set forth in claim 1, further comprising detecting inspiration time and expiration time for successive breaths.

3. A method as set forth in claim 1, further comprising detecting a ratio of inspiration time and expiration time.

4. A method as set forth in claim 3, further comprising generating an evaluation signal which gives information as to whether imminent or already existing breathing disorders are obstructively and/or centrally caused based on the change with respect to time of said ratios.

5. A method as set forth in claim 3, wherein the evaluation results which give information as to whether a breathing disorder phase is imminent are generated from comparative evaluation of successively occurring changes in properties of the derivatives.

6. A method as set forth in claim 2, further comprising describing breathing disorders using a ratio of inspiration time Ix to expiration time Ex.

7. A method as set forth in claim 2, wherein a change in the duration of the inspiration time with respect to the expiration time is indicative of an imminent obstruction in the upper respiratory tracts.

8. A method as set forth in claim 2, further comprising extracting the evaluation results for an existing or imminent disturbance phase from comparative consideration of successively occurring changes in properties of derivatives of, or within, respiratory cycles.

9. A method as set forth in claim 2, wherein consideration is directed to the curve shape during the inspiration cycle.

10. A method as set forth in claim 9, further comprising calculating an average gradient in simple form for intervals which extend over a predetermined percentage of the time duration of the respective breathing phase.

11. A method as set forth in claim 9, further comprising variably calculating a gradient at the phase change within a window over the inspiration cycle.

12. A method as set forth in claim 1, further comprising performing trend analysis based on the nature and constitution of breathing drive.

13. A method as set forth in claim 12, further comprising performing the trend analysis based on one or more of the following signal evaluation results:

max. peak flow during the inspiration cycle, the breath volume, the inspiration time, and the second derivative of the measured flow curve.

14. A method as set forth in claim 1, further comprising performing an evaluation procedure that includes consideration of the maximum peak flow during the expiration cycle, the breath volume and/or the expiration time and/or the second derivative or curvature of the measured flow curve during the expiration cycle.

15. A method as set forth in claim 14, further comprising generating, based on the evaluation procedure, an evaluation result which furnishes information about the nature and the constitution of the upper respiratory tracts.

16. A method as set forth in claim 1, further comprising performing trend analysis of the evaluation results including combined consideration of at least two parameters.

17. A method as set forth in claim 16, wherein the trend analysis is based on consideration of the variation in the ratios between two of the following parameters:

inspiration time, expiration time, breath duration, breath frequency, breath volume during the inspiration cycle, breath volume during the expiration cycle, first differential and second differential of the respiratory flow, amplitudes of local maxima and local minima, frequency of local maxima and local minima, inflexion points, maximum inspiratory flow, and maximum expiratory flow.

18. An apparatus for carrying out the method as set forth in claim 1.

19. A method as set forth in claim 5, wherein the derivative is the first derivative of the respiratory gas flow in the region of the breathing phase change.

20. A method as set forth in claim 8, wherein the derivative is the first derivative of the respiratory gas flow in the region of the breathing phase change.

21. A method as set forth in claim 10, wherein the predetermined percentage is 10%.

22. A method of carrying out signal-processing consideration of a measurement signal related to the respiration activity of a person when matching pressure regulation in administering a breathable gas at a pressure level which at least in phase-wise manner is above ambient pressure, the method comprising:

differentiating the measurement signal on a positive airway pressure (PAP) device to generate evaluation results indicative of the respiratory gas flow, the differentiating permitting classification between obstructive and central breathing disorders;

detecting inspiration time and expiration time for successive breaths; and

extracting the evaluation results for an existing or imminent disturbance phase from comparative consideration of successively occurring changes in properties of derivatives of, or within, respiratory cycles,

wherein consideration of the derivatives is directed to the beginning of the inspiration cycle and/or to the end of the inspiration cycle.

23. A method of carrying out signal-processing consideration of a measurement signal related to the respiration activity of a person when matching pressure regulation in administering a breathable gas at a pressure level which at least in phase-wise manner is above ambient pressure, the method comprising:

differentiating the measurement signal on a positive airway pressure (PAP) device to generate evaluation results indicative of the respiratory gas flow, the differentiating permitting classification between obstructive and central breathing disorders,

wherein the signal-processing consideration is carried out based on consideration of a derivative taken at the beginning of the expiration cycle or at the end of the expiration cycle respectively.

24. A method as set forth in claim 23, further comprising calculating the derivative either (a) in a simple form over a predetermined interval at the beginning of the expiration cycle and after the expiratory maximum flow, or (b) variably over the expiration cycle.

25. A method as set forth in claim 24, wherein the predetermined interval is 10%.

26. A method of carrying out signal-processing consideration of a measurement signal related to the respiration activity of a person when matching pressure regulation in administering a breathable gas at a pressure level which at least in phase-wise manner is above ambient pressure, the method comprising:

differentiating the measurement signal on a positive airway pressure (PAP) device to generate evaluation results indicative of the respiratory gas flow, the differentiating permitting classification between obstructive and central breathing disorders; and

analyzing the number of local maxima and minima, the amplitude of the local maxima and minima, the sequence of the magnitude of the amplitudes of local maxima and minima, and the frequency in the sequence of local maxima and minima in considering the configuration of the curve shape.

27. A method of carrying out signal-processing consideration of a measurement signal related to the respiration activity of a person when matching pressure regulation in administering a breathable gas at a pressure level which at least in phase-wise manner is above ambient pressure, the method comprising:

differentiating the measurement signal on a positive airway pressure (PAP) device to generate evaluation results indicative of the respiratory gas flow, the differentiating permitting classification between obstructive and central breathing disorders; and

performing spectral consideration and consideration in respect of amplitude of a snoring signal.

28. A method of carrying out signal-processing consideration of a measurement signal related to the respiration activity of a person when matching pressure regulation in administering a breathable gas at a pressure level which at least in phase-wise manner is above ambient pressure, the method comprising:

differentiating the measurement signal on a positive airway pressure (PAP) device to generate evaluation results indicative of the respiratory gas flow, the differentiating permitting classification between obstructive and central breathing disorders; and

generating evaluation results based on an evaluation procedure which give information about at least one of the following;

the nature of the upper respiratory tracts, at least for differentiating between central and obstructive apneas,

the elastic properties of the upper respiratory tracts,

the location of an obstruction,

the degree of severity of a sleep apnea, and

the Pcrit-value.

29. A method as set forth in claim 28, wherein the elastic properties of the upper respiratory tracts include restoring modulus and/or modulus of elasticity.

30. An apparatus for supplying a respiratory gas to a patient at a pressure level which is above the ambient pressure at least in phase-wise manner, comprising

a delivery device for delivering the respiratory gas,

a measuring device for generating a signal indicative of the respiratory gas flow,

a regulating device for regulating the respiratory gas pressure to a predetermined reference pressure,

a pressure presetting device for presetting the reference pressure, and

a signal processing device configured to generate, based on a variation in respiratory cycle-specific reference features obtained via differentiation, an evaluation result which is indicative of whether or to what extent a prevailing or imminent breathing disorder is of obstructive or central origin,

wherein the reference pressure is determined having regard to said evaluation result, and

wherein the evaluation result indicative of whether or to what extent a prevailing or imminent breathing disorder is of obstructive or central origin is based solely on a variation in respiratory cycle-specific reference features obtained via differentiation.

31. The apparatus as set forth in claim 30, further comprising a respiratory gas line extending between the delivery device and a breathing mask.

32. An evaluation apparatus for evaluation of a series of measurement data which contains items of information indicative in respect of the pattern in respect of time of the breathing of a patient, comprising:

a signal processing device configured to generate, based on a variation in respiratory cycle-specific reference features obtained via differentiation, evaluation results indicative of whether or to what extent the measurement series contains sequences which are to be classified as a breathing disorder of obstructive or central origin,

wherein the signal processing device is configured to generate the evaluation result based on the variation in respiratory cycle-specific reference features obtained directly via differentiation.

33. An evaluation apparatus as set forth in claim 32, further comprising a display configured to visualize the measurement series at least in portion-wise manner and to distinguish sequences of presumed disturbed breathing as sequences of obstructive or central origin.

34. A method of carrying out signal-processing consideration of a measurement signal related to the respiration activity of a person when matching pressure regulation in administering a breathable gas at a pressure level which at least in phase-wise manner is above ambient pressure, the method comprising:

generating evaluation results of the measurement signal, on a positive airway pressure (PAP) device, indicative of the respiratory gas flow, the evaluation results permitting classification between obstructive and central breathing disorders; and

analyzing, on the PAP device, the number of local maxima and minima, the amplitude of the local maxima and minima, the sequence of the magnitude of the amplitudes of local maxima and minima, and the frequency in the sequence of local maxima and minima in considering the configuration of the curve shape.

35. A method of carrying out signal-processing consideration of a measurement signal related to the respiration activity of a person when matching pressure regulation in administering a breathable gas at a pressure level which at least in phase-wise manner is above ambient pressure, the method comprising:

generating evaluation results of the measurement signal, on a positive airway pressure (PAP) device, indicative of the respiratory gas flow, the evaluation results permitting classification between obstructive and central breathing disorders,

wherein the signal processing further includes spectral consideration and consideration in respect of amplitude of a snoring signal, the signal processing being performed on the PAP device.

36. A method of carrying out signal-processing consideration of a measurement signal related to the respiration activity of a person when matching pressure regulation in administering a breathable gas at a pressure level which at least in phase-wise manner is above ambient pressure, the method comprising:

generating evaluation results of the measurement signal, on a positive airway pressure (PAP) device, indicative of the respiratory gas flow, the evaluation results permitting classification between obstructive and central breathing disorders,

wherein said evaluation results are generated on the PAP device based on an evaluation procedure which gives information about at least one of the following;

the nature of the upper respiratory tracts, at least for differentiating between central and obstructive apneas, the elastic properties of the upper respiratory tracts (including restoring modulus and/or modulus of elasticity), the location of an obstruction, the degree of severity of a sleep apnea, and the Pcrit-value.

37. A method of carrying out signal-processing consideration of a measurement signal related to the respiration activity of a person when matching pressure regulation in administering a breathable gas at a pressure level which at least in phase-wise manner is above ambient pressure, the method comprising:

generating evaluation results of the measurement signal on a positive airway pressure (PAP) device, the evaluation results permitting classification between obstructive and central breathing disorders and being indicative of the respiratory gas flow via differentiation,

wherein the signal-processing consideration is carried out on the PAP device (1) based on consideration of a derivative taken at the beginning of the inspiration cycle or at the end of the inspiration cycle, and/or (2) based on consideration of a derivative taken at the beginning of the expiration cycle or at the end of the expiration cycle.

38. A method of carrying out signal-processing consideration of a measurement signal related to the respiration activity of a person when matching pressure regulation in administering a breathable gas at a pressure level which at least in phase-wise manner is above ambient pressure, the method comprising:

differentiating the measurement signal on a positive airway pressure (PAP) device to generate evaluation results indicative of the respiratory gas flow, the differentiating permitting classification between obstructive and central breathing disorders,

wherein classification between obstructive and central breathing disorders is based on variables and/or mathematical operations consisting essentially of the differentiating.