SYSTEMS AND METHODS FOR PROCESSING PHYSIOLOGICAL SIGNALS IN WAVELET SPACE

• US 20140094672A1
• Filed: 12/06/2013
• Published: 04/03/2014
• Est. Priority Date: 07/06/2009
• Status: Abandoned Application

• Current Assignee: Nellcor Puritan Bennett Ireland
• Original Assignee: Nellcor Puritan Bennett Ireland
• Inventors: Ochs, James P., Addison, Paul Stanley, Watson, James N.
• Application Number:
  US14/099,146
• Publication Number:
  US 20140094672A1
• Time in Patent Office: Days
• US Class Current: 600/364
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 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 5/14542 for measuring blood gases A61B5/14551 takes precedence
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/7207 of noise induced by motion artifacts
• CPC Class Codes: A61B 5/7225 Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation A61B5/30, A61B5/316 take precedence; transformers for specific applications H01F38/00; amplifiers H03F
• CPC Class Codes: A61B 5/7235 Details of waveform analysis A61B5/349 takes precedence
• CPC Class Codes: A61B 5/726 using Wavelet transforms
• CPC Class Codes: A61B 5/7264 Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems neural networks per se G06N3/00; expert systems per se G06N5/00

Abstract

Methods and systems are disclosed for analyzing multiple scale bands in the scalogram of a physiological signal in order to obtain information about a physiological process. An analysis may be performed to identify multiple scale bands that are likely to contain the information sought. Each scale band may be assessed to determine a band quality, and multiple bands may be combined based on the band quality. Information about a physiological process may determined based on the combined band. In an embodiment, analyzing multiple scale bands in a scalogram arising from a wavelet transformation of a photoplethysmograph signal may yield clinically relevant information about, among other things, the blood oxygen saturation of a patient.

Claims

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

receiving, from a sensor, the physiological signal;

determining, using a processor, a pulse rate of the subject based at least in part on the physiological signal;

transforming, using the processor, the physiological signal into a transformed signal based at least in part on a wavelet transform;

determining, using the processor, a quality associated with each of a plurality of scales of the transformed signal, wherein each of the plurality of scales is based at least in part on the pulse rate;

combining, using the processor, the plurality of scales of the transformed signal to generate combined scale data based at least in part on the associated qualities; and

determining, using the processor, physiological information of the subject based at least in part on the combined scale data.

2. The method of claim 1, wherein the plurality of scales corresponds to scales associated with the pulse rate and multiples of the pulse rate.

3. The method of claim 1, wherein the plurality of scales comprises a first scale corresponding to the pulse rate, a second scale corresponding to two times the pulse, and a third scale corresponding to three times the pulse rate.

4. The method of claim 1, wherein combining the plurality of scales comprises calculating a weighted combination based on each of the plurality of scales, wherein the weight associated with each of the plurality of scales is based at least in part on a corresponding associated quality.

5. The method of claim 1, further comprising removing a portion of a scale over a time interval based at least in part on a quality over the time interval.

6. The method of claim 1, further comprising:

receiving, from the sensor, a second physiological signal; and

transforming, using the processor, the second physiological signal into a second transformed signal based at least in part on a wavelet transform, wherein determining the quality associated with each of the plurality of scales is based on the transformed signal and the second transformed signal.

7. The method of claim 1, wherein determining the quality associated with each of a plurality of scales comprises measuring the consistency of features in the transformed signal.

8. The method of claim 1, wherein determining the quality associated with each of a plurality of scales comprises comparing energy of a scale and energy of the plurality of scales.

9. The method of claim 1, wherein determining the quality associated with each of a plurality of scales comprises assessing noise in the transformed signal.

10. The method of claim 1, wherein determining the physiological information of the subject comprises determining blood oxygen saturation of the subject.