Systems and methods for variable filter adjustment by heart rate metric feedback

• US 9,801,552 B2
• Filed: 07/25/2012
• Issued: 10/31/2017
• Est. Priority Date: 08/02/2011
• Status: Active Grant

• Current Assignee: Yukka Magic LLC
• Original Assignee: Valencell, Inc.
• Inventors: Romesburg, Eric Douglas
• Primary Examiner(s): Layno, Carl H
• Assistant Examiner(s): GHAND, JENNIFER LEIGH-STEWAR
• Application Number:
  US14/124,465
• Publication Number:
  US 20140114147A1
• Time in Patent Office: 1,924 Days
• Field of Search: None
• 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 5/0095 by applying light and detecting acoustic waves, i.e. photoacoustic measurements
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/316 Modalities, i.e. specific diagnostic methods
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/369 Electroencephalography [EEG] devices for psychotechnics A61B5/16
• 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 5/725 using specific filters therefor, e.g. Kalman or adaptive filters A61B5/316 take precedence
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence

Abstract

A physiological signal processing system for a physiological waveform that includes a cardiovascular signal component provides a variable high pass filter that is responsive to the physiological waveform, and that is configured to high pass filter the physiological waveform in response to a corner frequency that is applied. A heart rate metric extractor is responsive to the variable high pass filter and is configured to extract a heart rate metric from the physiological waveform that is high pass filtered. A corner frequency adjuster is responsive to the heart rate metric extractor and is configured to determine the corner frequency that is applied to the variable high pass filter, based on the heart rate metric that was extracted. Analogous methods may also be provided.

Claims

1. A physiological signal processing system comprising:

a physiological sensor that is configured to generate a physiological waveform that includes cardiovascular and pulmonary signal components therein;

a variable high pass filter and a variable low pass filter that are responsive to the physiological waveform and that are configured to high pass and low pass filter, respectively, the physiological waveform in response to at least one corner frequency that is applied thereto;

a heart rate metric extractor that is coupled to an output of the variable high pass filter and is responsive to the variable high pass filter and that is configured to extract a heart rate metric from the cardiovascular signal component of the physiological waveform that is output from the variable high pass filter responsive to high pass filtering the physiological waveform;

a respiration rate metric extractor that is coupled to an output of and is responsive to the variable low pass filter and that is configured to extract a respiration rate metric from the pulmonary signal component of the physiological waveform that is output from the variable low pass filter responsive to low pass filtering the physiological waveform; and

a corner frequency adjustor that is responsive to the heart rate metric extractor and that is configured to determine the at least one corner frequency that is applied to the variable high pass filter and the variable low pass filter from the heart rate metric that was extracted based on the output from the variable high pass filter.

2. A physiological signal processing system for a physiological waveform that includes a cardiovascular signal component therein, the physiological signal processing system comprising:

a variable high pass filter that is responsive to the physiological waveform and that is configured to high pass filter the physiological waveform in response to a corner frequency that is applied thereto;

a heart rate metric extractor that is coupled to an output of the variable high pass filter and is responsive to the variable high pass filter and that is configured to extract a heart rate metric from the cardiovascular signal component of the physiological waveform that is output from the variable high pass filter responsive to high pass filtering the physiological waveform; and

a corner frequency adjustor that is responsive to the heart rate metric extractor and that is configured to determine the corner frequency that is applied to the variable high pass filter from the heart rate metric that was extracted based on the output from the variable high pass filter.

3. A physiological signal processing system according to claim 2 wherein the physiological waveform comprises an electrical physiological waveform including an electroencephalogram (EEG), an electrocardiogram (ECG) and/or a radio frequency (RF) waveform, an electro-optical physiological waveform including a photoplethysmograph (PPG) waveform, an electro-photoacoustic waveform including a photoacoustic waveform, an electro-mechanical physiological waveform including an auscultation waveform, a piezo sensor waveform and/or an accelerometer waveform, and/or an electro-nuclear physiological waveform.

4. A physiological signal processing system according to claim 2 wherein the variable high pass filter comprises a single high pass filter having an adjustable corner frequency.

5. A physiological signal processing system according to claim 2 wherein the variable high pass filter comprises a plurality of high pass filters, a respective one of which includes a different value of the corner frequency, and wherein the corner frequency adjustor is configured to select one of the plurality of high pass filters that corresponds to the corner frequency that is determined.

6. A physiological signal processing system according to claim 2 wherein the variable high pass filter comprises a variable digital high pass filter having a plurality of delay taps and wherein the corner frequency corresponds to a number of the plurality of delay taps that are selected to filter the physiological waveform.

7. A physiological signal processing system according to claim 6 wherein the corner frequency adjustor comprises a mapping system that is configured to map the heart rate metric that is extracted from the physiological waveform that is filtered into the number of the delay taps that are selected to high pass filter the physiological waveform.

8. A physiological signal processing system according to claim 2 wherein the corner frequency adjustor is configured to reduce locking on an erroneous heart rate metric.

9. A physiological signal processing system according to claim 2 wherein the corner frequency adjustor is configured to initially set a predetermined corner frequency corresponding to a predetermined heart rate prior to determining the corner frequency that is applied to the variable high pass filter from the heart rate metric.

10. A physiological signal processing system according to claim 9 wherein the predetermined heart rate is a resting heart rate.

11. A physiological signal processing system according to claim 9 wherein the corner frequency adjustor is configured to initially set the predetermined corner frequency corresponding to the predetermined heart rate until the heart rate metric extractor locks on a heart rate in the physiological waveform.

12. A physiological signal processing system according to claim 9 wherein the corner frequency adjustor is configured to reset the predetermined corner frequency corresponding to the predetermined heart rate in response to determining that the physiological sensor is no longer responsive to a source of the physiological waveform.

13. A physiological signal processing system according to claim 2 wherein the corner frequency adjustor is configured to set a predetermined corner frequency corresponding to a predetermined heart rate in response to determining that the physiological sensor is not responsive to a source of the physiological waveform.

14. A physiological signal processing system according to claim 2 wherein the corner frequency adjustor is configured to determine the corner frequency that is applied to the variable high pass filter from the heart rate metric by applying a margin to the heart rate metric.

15. A physiological signal processing system according to claim 2 wherein the variable high pass filter includes a gradual filter transition band.

16. A physiological signal processing system according to claim 2 further comprising:

a physiological metric assessor that is responsive to the heart rate metric extractor and that is configured to process the heart rate metric to generate at least one physiological assessment.

17. A physiological signal processing system according to claim 2, wherein the corner frequency adjustor is configured to determine the at least one corner frequency that is applied to the variable high pass filter based on the heart rate metric independent of a respiration rate metric.

18. A physiological signal processing method for a physiological waveform that includes a cardiovascular signal component therein, the physiological signal processing method comprising:

high pass filtering the physiological waveform in response to an adjustable high pass filter corner frequency;

extracting a heart rate metric from the cardiovascular signal component of the physiological waveform that is output from the high pass filtering; and

determining the adjustable high pass filter corner frequency that is applied to the high pass filtering, from the heart rate metric that was extracted based on the output from the high pass filtering.

19. A physiological signal processing method according to claim 18 further comprising:

initially setting a predetermined corner frequency corresponding to a predetermined heart rate prior to the determining the at least one corner frequency that is applied to the variable high pass filtering from the heart rate metric.

20. A physiological signal processing method according to claim 19 wherein the initially setting the predetermined corner frequency comprises initially setting the predetermined corner frequency corresponding to the predetermined heart rate until the extracting locks on a heart rate in the physiological waveform.

21. A physiological signal processing method according to claim 19 further comprising:

resetting the predetermined corner frequency corresponding to the predetermined heart rate in response to determining that the physiological waveform is no longer being obtained.