System and method for removing artifacts from waveforms

• US 8,744,543 B2
• Filed: 05/21/2010
• Issued: 06/03/2014
• Est. Priority Date: 09/29/2005
• Status: Active Grant

• Current Assignee: Covidien PLC (Medtronic Plc)
• Sponsoring Entity: Covidien PLC (Medtronic Plc)
• Inventors: Li, Li, Mannheimer, Paul
• Primary Examiner(s): WINAKUR, ERIC FRANK
• APPLICATION: US 20100234696A1
• Time in USPTO: 1474 Days
• Field of Search: 600/310, 600/322, 600/323, 600/336, 600/500, 600/502
• US Class Current: 600/336
• CPC Class Codes: A61B 5/02416 : using photoplethysmograph signals, e.g. generated by infra-red 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: G06K 9/00516 : 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, the method performed on a processing component and comprising the acts of:

independently, identifying one or more artifacts in a physiological signal and performing one or more multi-resolution decompositions on the physiological signal to generate two or more decomposition products;

compensating for the one or more artifacts in the two or more decomposition products to generate modified decomposition products;

generating an artifact-compensated signal based on the modified decomposition products;

processing the artifact-compensated signal at a monitor to derive one or more physiological characteristics of interest; and

displaying the one or more physiological characteristics on the monitor.

2. The method of claim 1, comprising displaying the artifact-compensated signal on the monitor.

3. The method of claim 1, wherein the physiological characteristics comprise one or more of blood oxygen saturation, pulse rate, tissue water fraction, or tissue or blood carbon dioxide levels.

4. The method of claim 1, comprising locating portions of the two or more decomposition products that correspond to the identified artifacts.

5. The method of claim 4, wherein the two or more decomposition products comprise wavelet coefficients, and wherein compensation for artifacts comprises altering the values of the portions of the wavelet coefficients that correspond to artifacts.

6. A method for processing a signal using one or more of a sensor, a cable, or a monitor of a monitoring system comprising the acts of:

decomposing the signal based on at least frequency characteristics of the signal to generate a plurality of coefficients;

independently processing the signal to identify one or more artifacts within the signal;

setting the value of one or more coefficients corresponding to the one or more artifacts to zero to generate modified coefficients; and

generating a modified signal based on the modified coefficients.

7. The method of claim 6, comprising displaying a waveform based on the modified signal on the monitor.

8. The method of claim 6, comprising processing the modified signal at a downstream device to derive one or more physiological characteristics of interest.

9. The method of claim 8, comprising displaying the physiological characteristics on the monitor.

10. The method of claim 8, comprising providing an audible or visual notification based on a value of the one or more physiological characteristics.

11. The method of claim 6, wherein the decomposition of the signal is based on time characteristics of the signal as well as frequency characteristics.

12. A physiological monitoring system, comprising:

a sensor configured to generate a physiological signal;

a monitor configured to receive a form of the physiological signal from the sensor; and

one or more processing components disposed in one of the sensor, the monitor, or in a cable connecting the sensor and the monitor, wherein the one or more processing components are configured to identify one or more artifacts in the physiological signal and, in parallel with the act of identification, to perform one or more multi-resolution decompositions on the physiological signal to generate two or more decomposition products, to modify respective values of portions of the two or more decomposition products corresponding to the identified artifacts to generate modified decomposition products, and to reconstruct the modified decomposition products to generate an artifact-compensated signal.

13. The system of claim 12, wherein the one or more processing components are further configured to process the artifact-compensated signal to derive one or more physiological characteristics of interest.

14. The system of claim 12, wherein the monitor is configured to display

one or more physiological characteristics derived from the artifact-compensated signal.

15. The system of claim 12, wherein the two or more decomposition products are characterized by time and frequency.

16. The system of claim 12, wherein the two or more decomposition products comprise wavelet coefficients, and wherein the one or more processing components are configured to modify respective values of the wavelet coefficients by setting the portions of the wavelet coefficients that correspond to artifacts to zero.

17. A monitor, comprising:

one or more processing components configured to receive a physiological signal generated by a sensor, to identify one or more artifacts in the received physiological signal, to perform one or more wavelet decompositions on the received physiological signal to generate a plurality of wavelet coefficients in parallel with identifying the one or more artifacts, to modify values of one or more of the wavelet coefficients based on the identified artifacts to generate modified coefficients, and to reconstruct the modified decomposition products to generate an artifact-compensated signal.

18. The monitor of claim 17, wherein the one or more processing components are configured to transmit the artifact compensated signal to a monitor which is not configured to perform artifact compensation.

19. The monitor of claim 17, wherein the wavelet coefficients are characterized by time and frequency.

20. The monitor of claim 17, wherein modifying values of the wavelet coefficients comprises setting values for some of the wavelet coefficients to zero.