System and method for pre-processing waveforms

• US 20070073120A1
• Filed: 09/29/2005
• Published: 03/29/2007
• Est. Priority Date: 09/29/2005
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Nellcor Puritan Bennett LLC (Medtronic Plc)
• Inventors: Li, Li, Amundson, Scott, O'Neil, Michael
• Granted Patent: US 7,725,146 B2
• Time in Patent Office: Days
• US Class Current: 600/323
• CPC Class Codes: G06F 18/00 Pattern recognition
• CPC Class Codes: G06F 2218/02 Preprocessing

Abstract

A technique is provided for processing a physiological signal. The technique includes performing one or more multi-resolution decompositions on a physiological signal and one or more morphological operations on some or all of the respective decomposition components. In one embodiment, the technique is implemented as iteratively wavelet transformations where morphological operations, such as erosions and dilations, are applied to modify some or all of the respective wavelet coefficients. The modified wavelet coefficients may then be reconstructed to generate a clean version of the physiological signal from which some or all of the noise and/or artifacts have been removed.

Claims

1. A method for processing a physiological signal, the method comprising the acts of:

performing one or more multi-resolution decompositions on a physiological signal to generate high-passed components and low-passed components; and

performing one or more morphological operations on at least one of the high-passed components or the low-passed components generated by the one or more of the respective multi-resolution decompositions.

2. The method of claim 1, wherein the physiological signal is a waveform.

3. The method of claim 1, wherein the physiological signal is filtered.

4. The method of claim 3, wherein the physiological signal is median filtered.

5. The method of claim 1, wherein the one or more multi-resolution decompositions comprise one or more wavelet decompositions.

6. The method of claim 1, wherein the one or more morphological operations comprise at least one of an erosion or a dilation.

7. The method of claim 1, wherein the physiological signal comprises a pulse oximetry signal.

8. The method of claim 1, wherein the one or more multi-resolution decompositions and the one or more morphological operations are performed iteratively.

9. The method of claim 1, comprising iteratively performing one or more multi-resolution decompositions on respectively generated low-passed components.

10. The method of claim 1, wherein the one or more multi-resolution decompositions are implemented as a filter bank.

11. The method of claim 1, comprising reconstructing an output waveform from one or more modified wavelet coefficients generated by the one or more morphological operations.

12. The method of claim 11, wherein reconstructing the output waveform comprises performing an inverse wavelet transform of the one or more modified wavelet coefficients.

13. The method of claim 11 wherein the output waveform comprises a clean pulse oximetry signal.

14. One or more machine-readable media, comprising:

a routine configured to perform one or more multi-resolution decompositions on a physiological signal to generate high-passed components and low-passed components; and

a routine configured to perform one or more morphological operations on at least one of the high-passed components or the low-passed components generated by the one or more of the respective multi-resolution decompositions.

15. The one or more machine-readable media of claim 14, wherein the physiological signal is filtered.

16. The one or more machine-readable media of claim 14, wherein the one or more multi-resolution decompositions comprise one or more wavelet decompositions.

17. The one or more machine-readable media of claim 14, wherein the one or more morphological operations comprise at least one of an erosion or a dilation.

18. The one or more machine-readable media of claim 14, wherein the routine configured to perform the one or more multi-resolution decompositions and the routine for performing one or more morphological operations are implemented iteratively.

19. The one or more machine-readable media of claim 14, comprising a routine configured to iteratively perform one or more multi-resolution decompositions on respectively generated low-passed components.

20. The one or more machine-readable media of claim 14, wherein the one or more multi-resolution decompositions are implemented as a filter bank.

21. The one or more machine-readable media of claim 14, comprising a routine configured to reconstruct an output waveform from one or more modified wavelet coefficients generated by the one or more morphological operations.

22. The one or more machine-readable media of claim 21, wherein the routine configured to reconstruct the output waveform performs an inverse wavelet transform of the one or more modified wavelet coefficients.

23. A physiological monitoring system, comprising:

a sensor configured to generate a physiological signal; and

a monitor configured to display one or more physiological parameters derived from a modified version of the physiological signal, wherein the modified version is generated by performing one or more multi-resolution decompositions on the physiological signal to generate high-passed components and low-passed components, performing one or more morphological operations on at least one of the high-passed components or the low-passed components generated by the one or more of the respective multi-resolution decompositions, and reconstructing the modified version from one or more modified wavelet coefficients generated by the one or more morphological operations.

24. The physiological monitoring system of claim 23, wherein the physiological signal is filtered.

25. The physiological monitoring system of claim 23, wherein the one or more multi-resolution decompositions comprise one or more wavelet decompositions.

26. The physiological monitoring system of claim 23, wherein the one or more morphological operations comprise at least one of an erosion or a dilation.

27. The physiological monitoring system of claim 23, wherein the physiological signal comprises a pulse oximetry signal.

28. The physiological monitoring system of claim 23, wherein the one or more multi-resolution decompositions and the one or more morphological operations are performed iteratively.

29. The physiological monitoring system of claim 23, wherein the one or more multi-resolution decompositions are implemented as a filter bank.

30. A physiological monitoring system, comprising:

a sensor configured to generate a physiological signal; and

a monitor configured to perform one or more multi-resolution decompositions on the physiological signal to generate high-passed components and low-passed components, and configured to perform one or more morphological operations on at least one of the high-passed components or the low-passed components generated by the one or more of the respective multi-resolution decompositions.

31. The physiological monitoring system of claim 30, wherein the monitor is further configured to filter the physiological signal.

32. The physiological monitoring system of claim 30, wherein the one or more multi-resolution decompositions comprise one or more wavelet decompositions.

33. The physiological monitoring system of claim 30, wherein the one or more morphological operations comprise at least one of an erosion or a dilation.

34. The physiological monitoring system of claim 30, wherein the monitor is configured to perform the one or more multi-resolution decompositions and the one or more morphological operations iteratively.

35. The physiological monitoring system of claim 30, wherein the monitor is configured to iteratively perform one or more multi-resolution decompositions on respectively generated low-passed components.

36. The physiological monitoring system of claim 30, wherein the one or more multi-resolution decompositions are implemented as a filter bank.

37. The physiological monitoring system of claim 30, wherein the monitor is configured to reconstruct an output waveform from one or more modified wavelet coefficients generated by the one or more morphological operations.

38. The physiological monitoring system of claim 37, wherein the monitor is configured apply an inverse wavelet transform to the one or more modified wavelet coefficients to reconstruct the output waveform.