METHOD FOR MEASURING PHYSIOLOGICAL STRESS

• US 20100113893A1
• Filed: 10/11/2007
• Published: 05/06/2010
• Est. Priority Date: 10/12/2006
• Status: Abandoned Application

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Scepanovic, Danilo, Cohen, Richard J.
• Application Number:
  US12/445,139
• Publication Number:
  US 20100113893A1
• Time in Patent Office: Days
• US Class Current: 600/301
• 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 5/02405 Determining heart rate variability
• CPC Class Codes: A61B 5/091 Measuring volume of inspired or expired gases, e.g. to determine lung capacity
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/4035 Evaluating the autonomic nervous system
• CPC Class Codes: A61B 5/4818 Sleep apnoea
• CPC Class Codes: A61B 5/4884 inducing physiological or psychological stress, e.g. applications for stress testing

Abstract

Method for determining physiological stress. One or more physiologic signals in a subject is detected. The one or more physiologic signals are processed to obtain one or more processed signals. The subject'"'"'s stress level is estimated from the one or more processed signals. The one or more physiological signals may include the electrocardiogram, instantaneous lung volume or other signal reflecting respiratory activity, or the arterial blood pressure or other signal reflecting cardiovascular activity.

Claims

1. Method for determining physiological stress comprising:

detecting one or more physiologic signals in a subject;

processing the one or more physiologic signals to obtain one or more processed signals; and

estimating from the one or more processed signals the subject'"'"'s stress level.

2. The method of claim 1 wherein the one or more physiological signals includes the electrocardiogram, or the instantaneous lung volume or other signal reflecting respiratory activity, or the arterial blood pressure or other signal reflecting cardiovascular activity.

3. The method of claim 1 wherein the one or more processed signals includes the intervals between heart beats or the instantaneous heart rate.

4. The method of claim 1 wherein the processing step further includes computing the instantaneous rate of change, or the first difference, or the absolute value of the first difference, or the second difference, or the absolute value of the second difference.

5. The method of claim 1 further comprising computing shot noise, or a measure of spectral curvature or a correlation coefficient.

6. The method of claim 1 wherein the processing is conducted in real time.

7. The method of claim 1 wherein the processing is evaluated in a time window on the order of 1 to 10 seconds, or a time window of approximately 20 seconds, or a longer time window of one or more minutes.

8. The method of claim 1 further comprising computing the magnitude of sympathetic and parasympathetic activity.

9. The method of claim 8 wherein physiological stress is determined from a function of the sympathetic and parasympathetic activity.

10. The method of claim 8 wherein stress is estimated by computing S/P wherein S is sympathetic activity and P is parasympathetic activity.

11. The method of claim 8 wherein the stress is estimated by computing aS−

bP+c wherein S and P are sympathetic and parasympathetic activity respectively and a, b and c are constants.

12. The method of claim 1 further comprising the estimation of a transfer function.

13. The method of claim 1 further comprising the application of cardiovascular system identification (CSI).

14. The method of claim 1 further comprising computing a time-series of state vectors satisfying a Hidden Markov Model representation of hidden physiologic states and observable physiologic signals.

15. The method of claim 1 further comprising estimating Poisson process parameters.

16. The method of claim 1 further comprising the application of an integrate and fire model of the sino-atrial node.

17. The method of claim 8 wherein the magnitude of sympathetic and parasympathetic activity is computed by extrapolating short-window estimates to the “

infinite data set”

.

18. The method of claim 1 further comprising using the estimate of physiologic stress to determine whether a subject is lying (deceitful) or truthful when speaking spontaneously or when answering one or more questions.

19. The method of claim 1 wherein the estimate of physiologic stress is used to monitor the status of a patient.

20. Apparatus for determining physiological stress comprising:

means for detecting one or more physiologic signals in a subject;

processing means for processing the one or more physiologic signals to obtain one or more processed signals; and

means for estimating from the one or more processed signals the subject'"'"'s stress level.

21. The apparatus of claim 20 further comprising means for using the estimate of physiologic stress to determine whether a subject is lying (deceitful) or truthful when speaking spontaneously or when answering one or more questions.

22. The apparatus of claim 20 further including means for using the estimate of physiological stress to monitor the status of a patient.