SYSTEMS AND METHODS FOR COMPUTING A PHYSIOLOGICAL PARAMETER USING CONTINUOUS WAVELET TRANSFORMS

• US 20100016692A1
• Filed: 10/03/2008
• Published: 01/21/2010
• Est. Priority Date: 07/15/2008
• Status: Abandoned Application

• Current Assignee: Nellcor Puritan Bennett Ireland
• Original Assignee: Nellcor Puritan Bennett Ireland
• Inventors: Addison, Paul Stanley, Watson, James Nicholas
• Application Number:
  US12/245,451
• Publication Number:
  US 20100016692A1
• Time in Patent Office: Days
• US Class Current: 600/324
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• 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

Abstract

According to embodiments, systems and methods for computing a physiological parameter are provided. The physiological parameter may be calculated using a continuous wavelet transform technique as well as using a non-continuous wavelet transform technique. More than one value for the physiological parameter may be calculated using various techniques. The values may be evaluated to select a desired value, or an average or weighted average of the values may be computed to generate a desired value.

Claims

1. A method for determining a physiological parameter from a physiological signal, comprising:

receiving at least one physiological signal;

calculating a first value for a physiological parameter based at least in part on the at least one physiological signal using a continuous wavelet transform technique;

calculating a second value for the physiological parameter based at least in part on the at least one physiological signal using a non-continuous wavelet transform technique;

analyzing the first value and the second value; and

determining, based at least in part on the analysis of the first value and the second value, a desired value for the physiological parameter.

2. The method of claim 1 wherein the at least one physiological signal comprises a photoplethysmogram signal.

3. The method of claim 1 wherein analyzing the first value and second value comprises considering at least one of the group consisting of:

an expected range of values for the physiological parameter, historical information, patient information, a statistical measure, noise associated with the signal, a confidence indicator.

4. The method of claim 1 further comprising:

assigning a first weight to the first value; and

assigning a second weight to the second value;

wherein determining, based at least in part on the analysis of the first value and the second value, the desired value for the physiological parameter comprises calculating a weighted average of the first value and the second value.

5. The method of claim 4 wherein the first weight and the second weight are based on at least one of the group consisting of:

an expected range of values for the physiological parameter, historical information, patient information, a statistical measure, noise associated with the signal, a confidence indicator.

6. The method of claim 1 wherein the physiological parameter comprises one of the group consisting of:

blood oxygen saturation, pulse rate, respiration rate, blood pressure, and respiration effort.

7. The method of claim 1 wherein the continuous wavelet transform technique comprises:

performing a continuous wavelet transform of the at least one physiological signal;

generating at least one scalogram based at least in part on the continuous wavelet transform; and

analyzing features in the at least one scalogram.

8. The method of claim 7 wherein analyzing features in the at least one scalogram comprises a technique selected from the group consisting of:

following a ridge, generating a Lissajous figure based on amplitude values of two scalograms, and determining a ratio of an amplitude value of one scalogram to an amplitude value of another scalogram.

9. The method of claim 1 wherein the non-continuous wavelet transform technique comprises a technique selected from the group consisting of:

a time domain technique and a spectral technique.

10. A system for determining a physiological parameter from a physiological signal, the system comprising:

a sensor configured to generate at least one physiological signal; and

a processor configured to;

calculate a first value for a physiological parameter based at least in part on the at least one physiological signal using a continuous wavelet transform technique;

calculate a second value for the physiological parameter based at least in part on the at least one physiological signal using a non-continuous wavelet transform technique;

analyze the first value and the second value; and

determine, based at least in part on the analysis of the first value and the second value, a desired value for the physiological parameter.

11. The system of claim 10 wherein the at least one physiological signal comprises a photoplethysmogram signal.

12. The system of claim 10 wherein analyze the first value and second value comprises considering at least one of the group consisting of:

an expected range of values for the physiological parameter, historical information) patient information, a statistical measure, noise associated with the signal, a confidence indicator.

13. The system of claim 10 wherein the processor is configured to:

assign a first weight to the first value; and

assign a second weight to the second value; and

wherein determine, based at least in part on the analysis of the first value and the second value, the desired value for the physiological parameter comprises calculating a weighted average of the first value and the second value.

14. The system of claim 13 wherein the first weight and the second weight are based on at least one of the group consisting of:

an expected range of values for the physiological parameter, historical information, patient information, a statistical measure, noise associated with the signal, a confidence indicator.

15. The system of claim 10 wherein the physiological parameter comprises one of the group consisting of:

blood oxygen saturation, pulse rate, respiration rate, blood pressure, and respiration effort.

16. The system of claim 10 wherein the continuous wavelet transform technique is performed by the processor, further configured to:

perform a continuous wavelet transform of the at least one physiological signal;

generate at least one scalogram based at least in part on the continuous wavelet transform; and

analyze features in the at least one scalogram.

17. The system of claim 16 wherein the analyze features in the at least one scalogram comprises a technique selected from the group consisting of:

following a ridge, generating a Lissajous figure based on amplitude values of two scalograms, and determining a ratio of an amplitude value of one scalogram to an amplitude value of another scalogram.

18. The system of claim 10 wherein the non-continuous wavelet transform technique comprises a technique selected from the group consisting of:

a time domain technique and a spectral technique.

19. A computer-readable medium for use in determining a physiological parameter from a physiological signal, the computer-readable medium having computer program instructions recorded thereon for:

receiving at least one physiological signal;

calculating a first value for a physiological parameter based at least in part on the at least one physiological signal using a continuous wavelet transform technique;

calculating a second value for the physiological parameter based at least in part on the at least one physiological signal using a non-continuous wavelet transform technique;

analyzing the first value and the second value; and

determining, based at least in part on the analysis of the first value and the second value, a desired value for the physiological parameter.