Pulse Oximetry For Determining Heart Rate Variability As A Measure Of Susceptibility To Stress

• US 20120136226A1
• Filed: 11/29/2010
• Published: 05/31/2012
• Est. Priority Date: 11/29/2010
• Status: Abandoned Application

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Nellcor Puritan Bennett LLC (Medtronic Plc)
• Inventors: Wilke, Thomas A.
• Application Number:
  US12/955,187
• Publication Number:
  US 20120136226A1
• Time in Patent Office: Days
• US Class Current: 600/324
• CPC Class Codes: A61B 5/02405 Determining heart rate variability
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/165 Evaluating the state of mind, e.g. depression, anxiety
• CPC Class Codes: A61B 5/4884 inducing physiological or psychological stress, e.g. applications for stress testing

Abstract

Embodiments of the present disclosure relate to systems and methods for determining a physiologic parameter of a patient. Specifically, embodiments provided herein include methods and systems for determining or predicting the presence and/or severity of stress in a patient based on heart rate variability. The information relating to stress may be used as part of a broader physiological assessment.

Claims

1. A method of determining relative stress level in a subject comprising:

using a monitor to;

receive a signal from a pulse oximetry sensor, wherein the signal is representative of a heart rate of a patient;

determine a heart rate variability of the subject based at least in part on the signal; and

determine or predicting a stress response of the subject based in part on the heart rate variability, wherein a higher determined or predicted stress response is associated with increased heart rate variability relative to a baseline heart rate variability.

2. The method of claim 1, wherein the signal is from a time period.

3. The method of claim 2, wherein the time period is associated with a stress event.

4. The method of claim 2, wherein the time period is associated with a physical activity, a psychological test, or a physical stimulus.

5. The method of claim 2, comprising using the monitor to sample the signal at a higher rate during a period when heart rate variability is being determined and sample the signal at a lower rate when heart rate variability is not being determined.

6. The method of claim 5, wherein using the monitor to determine the heart rate variability comprises assessing pulse intervals from the signal and rejecting invalid pulse intervals.

7. The method of claim 1, comprising using the monitor to provide an indication of stress based on the heart rate variability.

8. The method of claim 1, wherein using the monitor to determine the heart rate variability comprises applying a smoothing filter to the signal.

9. The method of claim 1, comprising using the monitor to receive a second signal from the pulse oximetry sensor, wherein the second signal is used to determine a blood oxygen saturation and a heart rate of the subject.

10. A monitor, comprising:

an input circuit configured to receive a pulse oximetry signal;

a memory storing an algorithm configured to calculate a heart rate variability based at least in part on the pulse oximetry signal;

a processor configured to execute the algorithm;

and

a display configured to provide an indication of stress based on the heart rate variability, wherein the indication of stress is associated with increased heart rate variability relative to a threshold.

11. The monitor of claim 10, wherein the algorithm comprises determining a pulse interval.

12. The monitor of claim 10, wherein the algorithm comprises a beat-to-beat heart rate variability determination.

13. The monitor of claim 10, wherein the algorithm comprises a time domain heart rate variability determination.

14. The monitor of claim 10, wherein the algorithm comprises a frequency domain heart rate variability determination.

15. The monitor of claim 10, wherein the algorithm comprises a geometric heart rate variability determination.

16. The monitor of claim 10, wherein the algorithm uses a signal quality input to determine a sampling rate for the pulse oximetry signal.

17. The monitor of claim 10, wherein the indication of stress comprises a numerical index or a graphical icon.

18. A system for determining patient stress, comprising:

a sensor configured to acquire pulse oximetry data and generate a signal relating to the pulse oximetry data; and

a monitor configured to;

sample the signal at a rate of 2000 Hz or higher;

determine a heart rate variability based at least in part on the signal; and

provide an indication of stress based on the heart rate variability.

19. The system of claim 18, wherein the indication of stress is associated with an increased heart rate variability as compared to a threshold or baseline value.

20. The system of claim 19, wherein heart rate variability below the threshold or baseline value is associated with a lack of stress.