Selection of preset filter parameters based on signal quality

• US 20060030766A1
• Filed: 10/11/2005
• Published: 02/09/2006
• Est. Priority Date: 01/13/2003
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Stetson, Paul F.
• Granted Patent: US 8,983,800 B2
• Time in Patent Office: Days
• US Class Current: 600/336
• CPC Class Codes: A61B 5/01 Measuring temperature of body parts ; Diagnostic temperature sensing, e.g. for malignant or inflamed tissue clinical contact thermometers G01K13/20
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• 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 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61B 5/725 using specific filters therefor, e.g. Kalman or adaptive filters A61B5/316 take precedence
• CPC Class Codes: G06F 2218/02 Preprocessing

Abstract

Methods and devices for reducing noise effects in a system for measuring a physiological parameter, including receiving an input signal, obtaining an assessment of the signal quality of the input signal, selecting coefficients for a digital filter using the assessment of signal quality; and filtering the input signal using the digital filter, without comparing the filter'"'"'s output signal with the input signal.

Claims

1. A method comprising:

receiving a sequence of data inputs;

obtaining one or more digital filter coefficients for each data input of the sequence using at least one signal quality metric for each respective data input; and

filtering each data input using the respective one or more digital filter coefficients.

2. The method, as set forth in claim 1, wherein obtaining one or more digital filter coefficients comprises:

accessing a data bank of stored coefficients.

3. The method, as set forth by claim 1, wherein filtering each data input comprises:

filtering each data input in substantially real time.

4. The method, as set forth by claim 1, wherein filtering each data input comprises:

configuring a linear digital filter using the respective one or more digital filter coefficients for each respective data input.

5. The method, as set forth by claim 1, wherein filtering each data input comprises:

configuring a non-linear digital filter using the respective one or more digital filter coefficients for each respective data input.

6. The method, as set forth in claim 1, wherein the at least one signal quality metric comprises at least one of a measure of variance in a raw saturation signal, a measure of correlation between signals from different wavelengths, a measure of skew of a derivative waveform of the data signal or a combination thereof.

7. A method comprising:

receiving a sequence of inputs;

obtaining at least one signal quality metric for each data input;

obtaining a coefficient for a digital filter for each data input using the respective signal quality metric; and

filtering the respective data input using the digital filter.

8. The method, as set forth in claim 7, wherein the at least one signal quality metric comprises at least one of a measure of variance in a raw saturation signal, a measure of correlation between signals from different wavelengths, a measure of skew of a derivative waveform of the data signal or a combination thereof.

9. The method, as set fort in claim 7, wherein obtaining the coefficients comprises

deriving the coefficients using a non-linear function of the signal quality metric.

10. A system, comprising:

a sensor adapted to deliver a data signal having a sequence of data inputs; and

a digital filter configured to filter each respective data input based on a respective signal quality metric for each respective data input.

11. The system, as set forth by claim 10, wherein the digital filter is configured by one or more filter coefficients, wherein the one or more filter coefficients is selected based upon the respective signal quality metric for each respective data input.

12. The system, as set forth by claim 10, wherein the digital filter is configured to filter each data input in substantially real time.

13. The system, as set forth by claim 10, wherein the digital filter comprises a linear filter.

14. The system, as set forth by claim 10, wherein the digital filter comprises a non-linear filter.

15. A system for reducing noise effects in pulse oximetry, comprising:

a pulse oximetry sensor adapted to acquire a sequence of data inputs;

a processor configured to obtain a respective filter coefficient for each respective data input of the sequence based upon at least one signal quality metric of each respective data input; and

a digital filter configured to filter each respective data input using the respective filter coefficient.

16. The system, as set forth in claim 15, wherein the at least one signal quality metric comprises at least one of a measure of variance in a raw saturation signal, a measure of correlation between signals from different wavelengths, a measure of skew of a derivative waveform of the signal, or a combination thereof.

17. The system, as set forth in claim 15, wherein the digital filter coefficients are derived using a non-linear function of the signal quality metric.

18. A tangible machine readable medium comprising:

code configured to obtain one or more digital filter coefficients for each data input of a sequence using at least one signal quality metric for each respective data input; and

code configured to filter each data input using the respective one or more digital filter coefficients.

19. The tangible machine readable medium, as set forth in claim 18, wherein the code configured to obtain the one or more digital filter coefficients is configured to access a data bank.

20. The tangible machine readable medium, as set forth in claim 18, wherein the code configured to filter each data input filters each data input in substantially real time.

21. The tangible machine readable medium, as set forth in claim 18, wherein the code configured to filter each data input applies a linear filter.

22. The tangible machine readable medium, as set forth in claim 18, wherein the code configured to filter each data input applies a non-linear filter.

23. A monitor comprising:

a processor configured to;

determine a signal quality metric for each data input of an input signal;

determine a filter coefficient based upon the signal quality metric; and

digitally filter each data input using the respective filter coefficient.

24. The monitor, as set forth in claim 23, wherein the processor comprises a digital filter configurable by each respective filter coefficient.

25. The monitor, as set forth in claim 23, comprising a memory storing a plurality of filter coefficients, wherein the processor is configured to select each of the respective filter coefficients from among the plurality of filter coefficients.

26. The monitor, as set forth in claim 23, wherein the signal quality metric comprises at least one of a measure of variance in a raw saturation signal, a measure of correlation between signals from different wavelengths, a measure of skew of a derivative waveform of the signal, or a combination thereof.

27. The monitor, as set forth in claim 23, wherein the digital filter comprises a linear filter.

28. The monitor, as set forth in claim 23, wherein the digital filter comprises a non-linear filter.