Method and system for determining a physiological condition using a two-dimensional representation of R-R intervals

• US 8,880,156 B2
• Filed: 04/24/2009
• Issued: 11/04/2014
• Est. Priority Date: 05/08/2008
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Crompvoets, Floris Maria Hermansz, Ouwerkerk, Martin, Hessel, Henk Albert, Krans, Martijn, Westerink, Joanne Henriette Desiree Monique
• Primary Examiner(s): Layno, Carl H
• Assistant Examiner(s): ANTHONY, JESSICA LYNN
• Application Number:
  US12/990,977
• Publication Number:
  US 20110060235A1
• Time in Patent Office: 2,020 Days
• Field of Search: 600/512, 600/521, 600/300, 600508-509, 600/513, 600515-516, 600518-519, 600/523, 607/5, 607 17- 18
• 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 physiological condition of a person is determined in physiological condition determining system by using a sensor for sampling a plurality of heart beats of the person, and using a control unit to perform the acts of: extracting a series of cardiac R-R intervals from the heart beat samples, providing a two-dimensional representation of subsequent R-R intervals, wherein two subsequent R-R interval forms an entry in the two-dimensional representation resulting in a plurality of entries, 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.

Claims

1. A method for determining a physiological condition of a person, the method operating in a physiological condition determining system, the method comprising:

using a sensor of the physiological condition determining system for sampling a plurality of heart beats of the person;

extracting in a control unit of the physiological condition determining system a series of cardiac R-R intervals from the heart beat samples; and

using the control unit for providing a two-dimensional representation of subsequent R-R intervals, wherein two subsequent R-R intervals form an entry in the two-dimensional representation resulting in a plurality of entries in the two-dimensional representation,

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

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

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

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

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

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

model of subsequent R-R intervals.

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

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

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

7. The method of claim 1, comprising outputting from the control unit 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 of claim 1, comprising the step of outputting from the control unit at least one of an audio stimulus, visual stimulus, haptic stimulus for guiding the person such that the distance between a radius and an entry is minimized.

9. The method of 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, the system 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 intervals form an entry in the two-dimensional representation resulting in a plurality of entries in the two-dimensional representation,

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 a center of said closed curve coincides with said centroid;

determining of a distance between the closed curve and the plurality of 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, the method operating in a physiological condition determining system, the method comprising:

using a sensor of the physiological condition determining system for sampling a plurality of heart beats of the person;

extracting in a control unit of the physiological condition determining system, a series of cardiac R-R intervals from the heart beat samples; and

providing in the control unit a two-dimensional representation of subsequent R-R intervals, wherein two subsequent R-R intervals form an entry in the two-dimensional representation resulting in a plurality of entries in the two-dimensional representation,

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

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

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