SYSTEMS AND METHODS FOR IDENTIFYING VENTILATED BREATHING

• US 20150119664A1
• Filed: 10/24/2014
• Published: 04/30/2015
• Est. Priority Date: 10/28/2013
• Status: Abandoned Application

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Addison, Paul S., Ochs, James, Watson, James N.
• Application Number:
  US14/523,080
• Publication Number:
  US 20150119664A1
• Time in Patent Office: Days
• US Class Current: 600/323
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 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 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61B 5/7246 using correlation, e.g. template matching or determination of similarity
• CPC Class Codes: A61B 5/726 using Wavelet transforms
• CPC Class Codes: A61B 5/7275 Determining trends in physiological measurement data; Predicting development of a medical condition based on physiological measurements, e.g. determining a risk factor
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence
• CPC Class Codes: A61B 5/7282 Event detection, e.g. detecting unique waveforms indicative of a medical condition A61B5/4094, A61B5/4818, A61B5/349, A61B5/0823 take precedence
• CPC Class Codes: A61M 16/0051 with alarm devices
• CPC Class Codes: A61M 16/021 operated by electrical means A61M16/202 – A61M16/205 take precedence
• CPC Class Codes: A61M 2205/50 with microprocessors or computers
• CPC Class Codes: A61M 2205/581 by audible feedback
• CPC Class Codes: A61M 2205/583 by visual feedback
• CPC Class Codes: A61M 2205/584 having a color code

Abstract

Provided are systems and methods for processing a physiological signal in order to detect whether a patient'"'"'s breathing is being controlled by a ventilator. A signal, such as a photoplethysmograph (PPG) may be processed to determine one or more various metrics indicative of the consistency of the patient'"'"'s respiration.

Claims

1. A computer-implemented method comprising:

receiving a photoplethysmograph (PPG) signal;

generating, using processing circuitry, at least one signal indicative of respiration consistency based on the PPG signal;

identifying, using the processing circuitry, a presence of ventilated breathing based on the at least one signal indicative of respiration consistency; and

providing, using the processing circuitry, an indicator of ventilated breathing based on the identifying of the presence of ventilated breathing.

2. The method of claim 1, wherein generating at least one signal indicative of respiration consistency comprises:

performing a wavelet transform of the PPG signal;

generating a scalogram based on the wavelet transform;

identifying a first portion of the scalogram and a second portion of the scalogram associated with respiration; and

determining the consistency of the first portion and of the second portion.

3. The method of claim 2, wherein the first portion comprises a first scale band and the second portion comprises a second scale band distinct from the first scale band and associated with characteristic frequencies lower than those of the first scale band, the method further comprising calculating a respiration rate based on characteristic frequencies associated with the second scale band when it is determined that ventilated breathing is present.

4. The method of claim 1, wherein generating at least one signal indicative of respiration consistency comprises:

extracting a baseline signal from the PPG signal;

performing an autocorrelation of the baseline signal to generate an autocorrelation signal; and

calculating at least one metric based on the autocorrelation signal.

5. The method of claim 4, wherein the at least one metric comprises at least one of a peak amplitude metric, a time consistency metric, a peak within frequency range metric, a normalized slope metric, and a historical standard deviation metric.

6. The method of claim 1, wherein the generating, identifying and providing steps are performed for consecutive time windows of the PPG signal.

7. The method of claim 6, further comprising:

determining whether at least a threshold number of time windows in a predetermined number of the consecutive time windows are associated with ventilated breathing; and

determining a presence of ventilatory breathing across the predetermined number of consecutive time windows.

8. The method of claim 1 further comprising determining respiration information based on the presence of ventilated breathing.

9. The method of claim 8 wherein the respiration information comprises respiration rate.

10. A system comprising:

an input that receives a photoplethysmograph (PPG) signal from a sensor; and

processing circuitry for;

generating at least one signal indicative of respiration consistency based on the PPG signal,

identifying a presence of ventilated breathing based on the at least one signal indicative of respiration consistency, and

providing an indicator of ventilated breathing based on the identifying of the presence of ventilated breathing.

11. The system of claim 10, wherein the processing circuitry is further configured for:

performing a wavelet transform of the PPG signal;

generating a scalogram based on the wavelet transform;

identifying a first portion of the scalogram and a second portion of the scalogram associated with respiration; and

determining the consistency of the first portion and of the second portion.

12. The system of claim 11, wherein the first portion comprises a first scale band and the second portion comprises a second scale band distinct from the first scale band and associated with characteristic frequencies lower than those of the first scale band, the processing circuitry further configured for calculating a respiration rate based on characteristic frequencies associated with the second scale band when it is determined that ventilated breathing is present.

13. The system of claim 10, wherein the processing circuitry is further configured for:

extracting a baseline signal from the PPG signal;

performing an autocorrelation of the baseline signal to generate an autocorrelation signal; and

generating at least one metric based on the autocorrelation signal.

14. The system of claim 13, wherein the at least one metric comprises at least one of a peak amplitude metric, a time consistency metric, a peak within frequency range metric, a normalized slope metric, and a historical standard deviation metric.

15. The system of claim 10, wherein the processing circuitry is configured to perform the generating, identifying and providing steps for consecutive time windows of the PPG signal.

16. The system of claim 15, wherein the processing circuitry is further configured for:

determining whether at least a threshold number of time windows in a predetermined number of the consecutive time windows are associated with ventilated breathing; and

determining a presence of ventilatory breathing across the predetermined number of consecutive time windows.

17. The system of claim 10, wherein the processing circuitry is further configured for determining respiration information based on the presence of ventilated breathing.

18. The system of claim 17 wherein the respiration information comprises respiration rate.

19. A non-transitory computer-readable medium having computer program instruction stored thereon for performing the method comprising:

receiving a photoplethysmograph (PPG) signal;

generating at least one signal indicative of respiration consistency based on the PPG signal;

identifying a presence of ventilated breathing based on the at least one signal indicative of respiration consistency; and

providing an indicator of ventilated breathing based on the identifying of the presence of ventilated breathing.

20. The computer-readable medium of claim 19, wherein generating at least one signal indicative of respiration consistency comprises:

performing a wavelet transform of the PPG signal;

generating a scalogram based on the wavelet transform;

identifying a first portion of the scalogram and a second portion of the scalogram associated with respiration; and

determining the consistency of the first portion and of the second portion.