System and method for removing artifacts from waveforms

• US 9,204,844 B2
• Filed: 04/17/2014
• Issued: 12/08/2015
• Est. Priority Date: 09/29/2005
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Li, Li, Mannheimer, Paul D.
• Primary Examiner(s): WINAKUR, ERIC FRANK
• Application Number:
  US14/255,321
• Publication Number:
  US 20140228658A1
• Time in Patent Office: 600 Days
• US Class Current: 1/1
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/4875 Hydration status, fluid retention of the body
• CPC Class Codes: A61B 5/7207 of noise induced by motion artifacts
• CPC Class Codes: G06F 18/00 Pattern recognition
• CPC Class Codes: G06F 2218/06 by applying a scale-space analysis, e.g. using wavelet analysis

Abstract

A technique is provided for processing a physiological signal to compensate for artifacts. The technique includes identifying artifacts within the physiological signal. The technique also includes performing one or more multi-resolution decompositions, such as wavelet transformations, on the physiological signal and compensating for the identified artifacts in some or all of the respective decomposition components. The modified decomposition components may be reconstructed to generate an artifact-compensated signal which may be provided to a monitor or other device which is otherwise not configured to compensate for signal artifacts.

Claims

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

using one or more processors of a sensor, a cable coupling the sensor to a monitor, or an intermediate device disposed between the sensor and the monitor, or any combination thereof, to perform the steps of;

obtaining a physiological signal in a time domain from the sensor;

performing a wavelet decomposition on the physiological signal to generate two or more wavelet coefficients;

identifying one or more artifacts in the physiological signal in the time domain without using the wavelet decomposition results;

generating an artifact-compensated signal in the time domain based on the one or more artifacts that are identified in the time domain and the two or more wavelet coefficients; and

providing the artifact-compensated signal to the monitor, wherein the monitor is configured to display the artifact-compensated signal or to display one or more physiological parameters based on the artifact-compensated signal.

2. The method of claim 1, comprising processing the artifact-compensated signal to derive one or more physiological parameters using a processing component of the monitor.

3. The method of claim 2, wherein the monitor is configured to display the one or more physiological parameters, and wherein the physiological signal is an oximetry signal, and the one or more physiological parameters include blood oxygen saturation, pulse rate, tissue water fraction, or tissue or blood carbon dioxide levels, or any combination thereof.

4. The method of claim 1, comprising adjusting the two or more wavelet coefficients to reduce the two or more wavelet coefficients that correspond to the one or more artifacts identified in the time domain, prior to generating the artifact-compensated signal.

5. The method of claim 4, wherein generating the artifact-compensated signal comprises reconstructing the two or more wavelet coefficients using an inverse wavelet transform, after the two or more wavelet coefficients are adjusted to reduce the two or more wavelet coefficients that correspond to the one or more artifacts identified in the time domain.

6. The method of claim 4, wherein adjusting the two or more wavelet coefficients comprises minimizing the two or more wavelet coefficients that correspond to the one or more artifacts identified in the time domain.

7. The method of claim 1, comprising wirelessly transmitting the artifact-compensated signal to the monitor.

8. The method of claim 1, further comprising determining the one or more physiological parameters based on the artifact-compensated signal.

9. A method for processing a physiological signal, comprising:

using one or more processors of a sensor, a monitor, a cable coupling the sensor to the monitor, or an intermediate device disposed between the sensor and the monitor, or any combination thereof, to perform the steps of;

obtaining a physiological signal in a time domain from the sensor;

performing a wavelet decomposition on the physiological signal to generate two or more wavelet coefficients;

identifying one or more artifacts in the physiological signal in the time domain without using the wavelet decomposition results;

generating an artifact-compensated signal in the time domain based on the one or more artifacts that are identified in the time domain and the two or more wavelet coefficients; and

using the artifact-compensated signal to determine one or more physiological parameters.

10. The method of claim 9, wherein the physiological signal is an oximetry signal, and the one or more physiological parameters include blood oxygen saturation, pulse rate, tissue water fraction, or tissue or blood carbon dioxide levels, or any combination thereof.

11. The method of claim 9, comprising adjusting the two or more wavelet coefficients to reduce the two or more wavelet coefficients that correspond to the one or more artifacts identified in the time domain, prior to generating the artifact-compensated signal.

12. The method of claim 11, wherein generating the artifact-compensated signal comprises reconstructing the two or more wavelet coefficients using an inverse wavelet transform, after the two or more wavelet coefficients are adjusted to reduce the two or more wavelet coefficients that correspond to the one or more artifacts identified in the time domain.

13. The method of claim 11, wherein adjusting the two or more wavelet coefficients comprises minimizing the two or more wavelet coefficients that correspond to the one or more artifacts identified in the time domain.

14. The method of claim 11, wherein adjusting the two or more wavelet coefficients comprises setting a value of the two or more wavelet coefficients that correspond to the one or more artifacts to zero.

15. The method of claim 11, wherein the two or more coefficients are adjusted based on time information, frequency information, or a combination thereof, associated with the one or more artifacts identified in the time domain.

16. A method for processing a physiological signal, comprising:

using one or more processors to perform the steps of;

applying a wavelet transform to the physiological signal to generate a plurality of coefficients;

processing the physiological signal in the time domain, without using the wavelet transform results, to identify one or more artifacts within the physiological signal;

adjusting the plurality of coefficients to reduce one or more coefficients of the plurality of coefficients that correspond to the one or more artifacts identified in the time domain; and

reconstructing the adjusted plurality of coefficients using an inverse wavelet transform to generate an artifact-compensated signal in the time domain.

17. The method of claim 16, wherein the one or more processors are disposed within a sensor, a monitor, a cable configured to couple the sensor to the monitor, or an intermediate device positioned between the sensor and the monitor, or any combination thereof.

18. The method of claim 16, comprising providing the artifact-compensated signal to an external device that is physically separate from the one or more processors and is configured to display the artifact-compensated signal or to determine one or more physiological parameters based on the artifact-compensated signal.

19. The method of claim 18, comprising processing the artifact-compensated signal to derive one or more physiological parameters of interest using a processing component of the external device.

20. The method of claim 16, wherein the physiological signal is an oximetry signal, and the one or more physiological parameters include blood oxygen saturation, pulse rate, tissue water fraction, tissue or blood carbon dioxide levels, or a combination thereof.

21. The method of claim 16, wherein adjusting the plurality of coefficients comprises removing one or more coefficients that correspond to the one or more artifacts.