Signal Processing Systems and Methods for Analyzing Multiparameter Spaces to Determine Physiological States

• US 20100016680A1
• Filed: 10/01/2008
• Published: 01/21/2010
• Est. Priority Date: 07/15/2008
• Status: Active Grant

• Current Assignee: Nellcor Puritan Bennett Ireland
• Original Assignee: Nellcor Puritan Bennett Ireland
• Inventors: Addison, Paul Stanley, Watson, James Nicholas, McKenna, Edward M.
• Granted Patent: US 8,660,625 B2
• Time in Patent Office: Days
• US Class Current: 600/301
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/7207 of noise induced by motion artifacts
• CPC Class Codes: A61B 5/726 using Wavelet transforms
• CPC Class Codes: G06F 2218/06 by applying a scale-space analysis, e.g. using wavelet analysis
• CPC Class Codes: G06F 2218/12 Classification; Matching
• CPC Class Codes: G16H 50/20 for computer-aided diagnosis, e.g. based on medical expert systems

Abstract

The present disclosure relates to signal processing systems and methods, and more particularly, to systems and methods for analyzing multiparameter spaces to determine changes in a physiological state. In embodiments, a first signal and a second signal may be obtained, from which a first plurality of values of a physiological parameter may be determined. At least one of the signals also may be used to generate a scalogram derived at least in part from the signal. A second plurality of values may be determined based at least in part on a feature in the scalogram. The first and second plurality of values may then be associated, and a physiological state may be analyzed using the associated first and second values. In an embodiment, the signals may be PPG signals and the associated first and second values may include a parameter scatter plot that may permit a user to determine changes in a patient'"'"'s ventilation state over time.

Claims

1. A method for analyzing a physiological state, comprising:

obtaining a first signal and a second signal;

determining a first plurality of values of a physiological parameter using at least the first signal and the second signal;

deriving a scalogram from the first signal;

determining a second plurality of values based at least in part on a feature in the scalogram;

associating the first plurality of values with the second plurality of values; and

analyzing the physiological state based at least in part on the associated first and second plurality of values.

2. The method of claim 1, wherein the first signal and the second signal are photoplethysmograph signals from a user.

3. The method of claim 2, wherein the analyzing the physiological state comprises analyzing a ventilation state of the user.

4. The method of claim 2, wherein the physiological parameter corresponds at least in part to blood oxygen saturation of the user.

5. The method of claim 1, wherein the determining a second plurality of values based at least in part on a feature in the scalogram comprises selecting a plurality of scale values based at least in part on a respiration ridge in the scalogram.

6. The method of claim 1, wherein the determining a second plurality of values based at least in part on a feature in the scalogram comprises deriving a plurality of respiration rate values based at least in part on a respiration ridge in the scalogram.

7. The method of claim 1, wherein the associating the first plurality of values with the second plurality of values comprises deriving a parameter scatter plot.

8. The method of claim 73 wherein the analyzing the physiological state further comprises analyzing whether the parameter scatter plot is located within a threshold region.

9. The method of claim 8, wherein the threshold region is calibrated based at least in part upon at least a first portion of the first signal and at least a first portion of the second signal.

10. The method of claim 8, wherein the analyzing the physiological state further comprises calculating a slope value from the parameter scatter plot.

11. The method of claim 10, wherein the slope value having a lower value than a threshold value indicates a generally poor physiological state.

12. A system for analyzing a physiological state, the system comprising:

an input signal generator for generating a first signal and a second signal;

a processor coupled to the input signal generator; and

an output coupled to the input signal generator, wherein the output is capable of displaying information based at least in part on the analysis of the physiological state and wherein the processor is capable of;

determining a first plurality of values of a physiological parameter based at least in part upon at least the first signal and the second signal;

deriving a scalogram from the first signal;

determining a second plurality of values based at least in part on a feature in the scalogram;

associating the first plurality of values with the second plurality of values; and

analyzing the physiological state based at least in part on the associated first and second plurality of values.

17. The system of claim 12, wherein the output is an electronic device.

18. The system of claim 12, wherein the associating the first plurality of values with the second plurality of values comprises deriving a parameter scatter plot.

19. The method of claim 18, wherein the analyzing the physiological state further comprises analyzing whether the parameter scatter plot is located within a threshold region.

20. The method of claim 19, wherein the threshold region is calibrated based at least in part upon at least a first portion of the first signal and at least a first portion of the second signal.

13. The system of claim 13, wherein the input signal generator is a pulse oximeter coupled to a sensor.

14. The system of claim 13, wherein the first signal and the second signal are photoplethysmograph signals from a user.

15. The system of claim 14, wherein the analyzing the physiological state comprises analyzing a ventilation state of the user.

16. The system of claim 14, wherein the physiological parameter corresponds at least in part to blood oxygen saturation of a user.

21. A computer-readable medium for use in analyzing a physiological state, the computer-readable medium having computer program instructions recorded thereon for:

obtaining a first signal and a second signal;

determining a first plurality of values of a physiological parameter using at least the first signal and the second signal;

deriving a scalogram from the first signal;

determining a second plurality of values based at least in part on a feature in the scalogram;

associating the first plurality of values with the second plurality of values; and

analyzing the physiological state based at least in part on the associated first and second plurality of values.

22. The computer-readable medium of claim 21, wherein the associating the first plurality of values with the second plurality of values comprises deriving a parameter scatter plot.

23. The computer-readable medium of claim 22, wherein the analyzing the physiological state comprises calculating a slope value from the parameter scatter plot.

24. The computer-readable medium of claim 23, wherein the physiological state is the ventilation state of a patient.

25. The computer-readable medium of claim 24, wherein the slope value having a lower value than a threshold value indicates a generally poor ventilation state.

26. The computer-readable medium of claim 24, wherein the slope value having a higher value than a threshold value indicates a generally good ventilation state.