METHOD AND SYSTEM FOR DETERMINING A PHYSIOLOGICAL CONDITION

• US 20110060235A1
• Filed: 04/24/2009
• Published: 03/10/2011
• Est. Priority Date: 05/08/2008
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Ouwerkerk, Martin, Krans, Martijn, Hessel, Henk Albert, Crompvoets, Floris Maria Hermansz, Westerink, Joanne Henriette Desiree Monique
• Granted Patent: US 8,880,156 B2
• Time in Patent Office: Days
• US Class Current: 600/509
• CPC Class Codes: A61B 5/02405 Determining heart rate variability
• CPC Class Codes: A61B 5/02438 with portable devices, e.g. worn by the patient
• CPC Class Codes: A61B 5/16 Devices for psychotechnics using teaching or educational appliances G09B1/00 - G09B7/00; Testing reaction times ; Devices for evaluating the psychological state
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
• CPC Class Codes: A61B 5/486 Bio-feedback A61B5/375 takes precedence

Abstract

The present invention relates to a method for determining a physiological condition of a person, comprising sampling a plurality of heart beats of the person, extracting a series of cardiac R-R intervals from the heart beat samples, and providing a two-dimensional representation of subsequent R-R intervals, wherein two subsequent R-R interval forms an entry in the two-dimensional representation, wherein the method further comprises the steps of determining a centroid, an average radius and an average rotation frequency for the plurality of entries in the two-dimensional representation, determining a plurality of distances between the radius and each of the entries in the two-dimensional representation, and determining the physiological condition of the person using the radius in combination with the plurality of distances. An advantage with the present invention following from this solution is that the time it take for determining the coherent state of the person is minimized at the same time as it is possible to quickly detect a change in state as each of the entries are directly related to the radius of the ellipse. The present invention also relates to a corresponding system making use of such a determination method.

Claims

1. A method for determining a physiological condition of a person, comprising:

sampling a plurality of heart beats of the person;

extracting a series of cardiac R-R intervals from the heart beat samples; and

providing a two-dimensional representation of subsequent R-R intervals, wherein two subsequent R-R interval forms an entry in the two-dimensional representation, characterized in that the method further comprises the steps of;

determining a centroid, for the plurality of entries in the two-dimensional representation;

fitting a closed curve through the plurality of entries in the two-dimensional representation, wherein the center of said closed curve coincides with said centroid

determining the distances between the closed curve and the entries in the two-dimensional representation; and

determining the physiological condition of the person by determining if the determined distances are above or below a predetermined first threshold.

2. The method according to claim 1, further comprising the step of determining the variance between the entries in the two-dimensional representation in relation to a determined average radius of the closed curve.

3. The method according to claim 1, wherein the two-dimensional representation of entries is essentially a Poincaré

model of subsequent R-R intervals.

4. The method according to claim 1, wherein the step of providing a two-dimensional representation of subsequent R-R intervals comprises the step of transforming the two-dimensional representation of entries to coincide with a circle.

5. The method according to claim 1, wherein the physiological condition for the person is a measure of coherence for the person.

6. The method according to claim 1, wherein the step of fitting a closed curve through the plurality of entries in the two-dimensional representation is adapted for fitting an ellipse through the plurality of entries.

7. The method according to claim 1, further comprising the step of outputting at least one of an audio stimulus, visual stimulus, haptic stimulus if a change in the physiological condition is above or below a predetermined second threshold.

8. The method according to claim 1, further comprising the step of outputting at least one of an audio stimulus, visual stimulus, haptic stimulus for guiding the person such that the distance between the radius and an entry is minimized.

9. The method according to claim 1, wherein the physiological condition is determined for a plurality of persons for measuring at least one of indifference, true attention and anger of the persons during a time of decision taking.

10. A system for determining a physiological condition of a person, comprising:

at least one sensor for sampling a plurality of heart beats of the person; and

a control unit adapted for;

extracting a series of cardiac R-R intervals from the heart beat samples; and

providing a two-dimensional representation of subsequent R-R intervals, wherein two subsequent R-R interval forms an entry in the two-dimensional representation, characterized in that the control unit is further adapted for;

determining a centroid, for the plurality of entries in the two-dimensional representation;

fitting a closed curve through the plurality of entries in the two-dimensional representation, wherein the center of said closed curve coincides with said centroid;

determining of the distances between the closed curve and the entries in the two-dimensional representation; and

determining the physiological condition of the person by determining if the determined distances are above or below a predetermined first threshold.

11. A method for determining a physiological condition of a person, comprising:

sampling a plurality of heart beats of the person;

extracting a series of cardiac R-R intervals from the heart beat samples; and

providing a two-dimensional representation of subsequent R-R intervals, wherein two subsequent R-R interval forms an entry in the two-dimensional representation, characterized in that the method further comprises the steps of;

determining a centroid, an average radius and an average rotation frequency for the plurality of entries in the two-dimensional representation;

determining a plurality of distances between the radius and each of the entries in the two-dimensional representation; and

determining the physiological condition of the person using the radius in combination with the plurality of distances.