Signal processing techniques for aiding the interpretation of respiration signals

• US 8,444,570 B2
• Filed: 06/09/2009
• Issued: 05/21/2013
• Est. Priority Date: 06/09/2009
• Status: Active Grant

• Current Assignee: Nellcor Puritan Bennett Ireland
• Original Assignee: Nellcor Puritan Bennett Ireland
• Inventors: McGonigle, Scott, Addison, Paul S., Watson, James N.
• Primary Examiner(s): Natnithithadha, Navin
• Assistant Examiner(s): BLOCH, MICHAEL RYAN
• Application Number:
  US12/481,045
• Publication Number:
  US 20100312075A1
• Time in Patent Office: 1,442 Days
• Field of Search: 600/529, 600/538
• US Class Current: 600/529
• CPC Class Codes: A61B 2562/08 Sensors provided with means for identification, e.g. barcodes or memory chips
• CPC Class Codes: A61B 5/0002 Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network A61B5/07 takes precedence; transmission systems for measured values G08C; transmission H04B; transmission of digital information H04L; wireless communication networks H04W
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/08 Detecting, measuring or recording devices for evaluating the respiratory organs A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• 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 5/726 using Wavelet transforms
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence

Abstract

According to embodiments, a respiration signal may be processed to normalize respiratory feature values in order to improve and/or simplify the interpretation and subsequent analysis of the signal. Data indicative of a signal may be received at a sensor and may be used to generate a respiration signal. Signal peaks in the respiration signal may be identified and signal peak thresholds may be determined. The identified signal peaks may be adjusted based on the signal peak threshold values to normalize the respiration signal.

Claims

1. A method for processing a respiration signal comprising:

using a processor for;

obtaining the respiration signal, wherein the respiration signal comprises a plurality of signal peaks;

identifying one or more signal peaks of the plurality of signal peaks;

determining a signal peak threshold for the respiration signal based at least in part on the identified one or more signal peaks;

adjusting one or more signal peaks of the plurality of signal peaks based at least in part on the signal peak threshold to generate an adjusted respiration signal, wherein at least one of the plurality of signal peaks remains unchanged in the adjusted respiration signal;

determining a respiration parameter based at least in part on the adjusted respiration signal; and

reporting the determined respiration parameter.

2. The method of claim 1, wherein the respiration signal is obtained based at least in part on data received from a sensor.

3. The method of claim 1, further comprising generating the respiration signal from a PPG photoplethysmograph (PPG) signal, a transthoracic impedance signal, a capnograph signal, a nasal thermistor signal, or an electrocardiogram (EKG) signal.

4. The method of claim 3, wherein generating the respiration signal from the PPG signal comprises:

obtaining a PPG signal;

generating a scalogram based at least in part on received PPG signal;

analyzing one or more features within the scalogram; and

generating the respiration signal based at least in part on the one or more analyzed features.

5. The method of claim 1, wherein determining a signal peak threshold comprises determining an upper signal peak threshold value.

6. The method of claim 5, wherein adjusting one or more signal peaks of the plurality of signal peaks comprises:

comparing an amplitude value of a signal peak of the plurality of signal peaks with the upper signal peak threshold value; and

reducing the amplitude value of the signal peak to a value less than the upper signal peak threshold value.

7. The method of claim 5, wherein determining a signal peak threshold further comprises determining a lower signal peak threshold value.

8. The method of claim 7, wherein adjusting one or more signal peaks of the plurality of signal peaks comprises:

comparing an amplitude value of a signal peak of the plurality of signal peaks with the lower signal peak threshold value; and

increasing the amplitude value of the signal peak to a value greater than the lower signal peak threshold value.

9. The method of claim 1, wherein adjusting one or more signal peaks of the plurality of signal peaks comprises:

selecting a portion of the respiration signal surrounding a signal peak of the plurality of signal peaks; and

adjusting the selected portion of the respiration signal.

10. The method of claim 9, wherein adjusting the selected portion of the respiration signal comprises resealing the selected portion by a constant factor.

11. The method of claim 1, wherein the respiration parameter comprises a respiration rate and/or respirations effort.

12. A system for processing a respiration signal system comprising:

a processor coupled to a sensor, wherein the processor is configured to;

obtain the respiration signal, wherein the respiration signal comprises a plurality of signal peaks;

identify one or more signal peaks of the plurality of signal peaks;

determine a signal peak threshold for the respiration signal based at least in part on the identified one or more signal peaks;

adjust one or more signal peaks of the plurality of signal peaks based at least in part on the signal peak threshold to generate an adjusted respiration signal, wherein at least one of the plurality of signal peaks remains unchanged in the adjusted respiration signal;

determine a respiration parameter based at least in part on the adjusted respiration signal; and

report the determined respiration parameter.

13. The system of claim 12, wherein the sensor is configured to receive data and wherein the respiration signal is obtained based at least in part on data received from the sensor.

14. The system of claim 12, wherein the respiration signal is obtained from a PPG photoplethysmograph (PPG) signal, a transthoracic impedance signal, a capnograph signal, a nasal thermistor signal, or an electrocardiogram (EKG) signal.

15. The system of claim 12, wherein the processor is further configured to:

obtain a PPG signal;

generate a scalogram based at least in part on received PPG signal data;

analyze one or more features within the scalogram; and

generate the respiration signal based at least in part on the one or more analyzed features.

16. The system of claim 12, wherein the system determined signal peak threshold comprises an upper signal peak threshold value.

17. The system of claim 16, wherein the processor is further configured to:

compare an amplitude value of a signal peak of the plurality of signal peaks with the upper signal peak threshold value; and

reduce the amplitude value of the signal peak to a value less than the upper signal peak threshold value.

18. The system of claim 16, wherein the determined signal peak threshold comprises a lower signal peak threshold value.

19. The system of claim 18, wherein the processor is further configured to:

compare an amplitude value of a signal peak of the plurality of signal peaks with the lower signal peak threshold value; and

increase the amplitude value of the signal peak to a value greater than the lower signal peak threshold value.

20. The system of claim 12, wherein the processor is further configured to:

select a portion of the respiration signal surrounding a signal peak of the plurality of signal peaks; and

adjust the selected portion of the respiration signal.

21. The system of claim 20, wherein the processor is further configured to rescale the selected portion by a constant factor.

22. The system of claim 12, wherein the determined respiration parameter comprises a respiration rate and/or respiration effort.