Method for processing a series of cardiac rhythm signals (RR) and the use thereof for analysing a cardiac rhythm variability, in particular for assessing a patient's pain or stress

• US 8,352,020 B2
• Filed: 08/09/2005
• Issued: 01/08/2013
• Est. Priority Date: 09/20/2004
• Status: Active Grant

• Current Assignee: Centre Hospitalier Régional Universitaire de Lille, Universite De Droit Et Sante De Lille
• Original Assignee: Centre Hospitalier Régional Universitaire de Lille, Uiversite de Droite et de La Sante de Lille II
• Inventors: Logier, Régis, Jeanne, Mathieu, Tavernier, Benoît
• Primary Examiner(s): Layno, Carl H
• Assistant Examiner(s): Kimball, Jeremiah
• Application Number:
  US11/663,166
• Publication Number:
  US 20080132801A1
• Time in Patent Office: 2,709 Days
• Field of Search: 600/481./509/521
• US Class Current: 600/521
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
• CPC Class Codes: A61B 5/4821 Determining level or depth of anaesthesia A61B5/1106 takes precedence
• CPC Class Codes: A61B 5/4824 Touch or pain perception evaluation A61B5/4821 takes precedence
• CPC Class Codes: A61B 5/726 using Wavelet transforms

Abstract

The inventive method for processing an RR series comprises a plurality of (RR) samples representing time intervals (dti) between two successive heart beats or the inverse (1/dti) of said time intervals consists in selecting (N) (RRi) samples in a main time window having a predetermined length (n), in cutting said main window into (m) subwindows (F_j), in calculating an intermediate parameter (A1) for each subwindow (F_j) on the basis of the (RRi) samples contained in the subwindow (F_j) and in calculating a final parameter as a function of the intermediate parameters (A_j). The invention is used for analysing a cardiac rhythm variability, in particular for assessing a patient'"'"'s pain or stress.

Claims

1. A method for processing an RR series using a processing unit, the RR series consisting of a plurality of samples, each sample representing the time intervals separating two successive heart beats or the inverse of said time intervals, said method comprising:

selecting samples in a main time window having a predetermined length of time;

cutting said main window into subwindows;

calculating an intermediary parameter for each subwindow on the basis of the samples contained in the subwindow; and

calculating a final parameter as a function of the intermediary parameters.

2. Method according to claim 1, wherein the final parameter is calculated by iteration, by shifting the main time window by a predetermined time interval less than the length of time of the main window.

3. Method according to claim 1, wherein each intermediary parameter is a function at least of the minima of the RR series in the subwindow when the samples of the series represent the time intervals separating two successive heart beats, or is a function at least of the maxima of the RR series in the subwindow when the samples of the series represent the inverse of the time intervals separating two successive heart beats.

4. Method according to claim 1, wherein the calculated value for the final parameter is proportional to the maximum value of the intermediary parameters.

5. Method according to claim 1, wherein the calculated value for the final parameter is proportional to the average value of the intermediary parameters.

6. Method according to claim 1, wherein, for the calculation of the intermediary parameters, an envelope is defined, linking the minimum points measured when the samples of the series represent the time intervals separating two successive heart beats, or linking the maximum points measured when the samples of the series represent the inverse of the time intervals separating two successive heart beats.

7. Method according to claim 6, wherein each intermediary parameter is a function of an area delimited by the envelope.

8. Method according to claim 1, wherein, prior to the calculation of the intermediary parameters, the RR series is filtered by means of a high-pass filter with a cut-off frequency superior or equal to 0.1 Hz.

9. Method according to claim 1, wherein, prior to the calculation of the intermediary parameters, in each subwindow, the samples of the RR series are normalised over the entire width of the main window.

18. Method according to claim 1, wherein, prior to the calculation of the intermediary parameters, the RR series is filtered by means of a high-pass filter with a cut-off frequency between 0.1 Hz and 0.15 Hz.

10. A system for analysing the variability of a cardiac rhythm, said system comprising:

means of acquiring an analogue cardiac signal;

means of sampling said cardiac signal; and

means of processing the sampled signal, designed to construct an RR series consisting of a plurality of samples, each sample representing the time intervals separating two successive heart beats or the inverse of said time intervals, wherein said processing means are furthermore designed to calculate automatically from the series at least one final parameter by selecting samples in a main time window having a predetermined length of time, cutting said main window into subwindows, calculating an intermediary parameter for each subwindow on the basis of the samples contained in the subwindow, and calculating said at least one final parameter as a function of the intermediary parameters.

11. System according to claim 10 for the assessment of pain, the final calculated parameter characterising a level of pain.

12. System according to claim 10 for the assessment of stress, the final calculated parameter characterising a level of stress.

13. System according to claim 10 for the assessment of pain felt by a living being.

14. System according to claim 10 for the assessment of stress felt by a living being.

15. A method for analysing the variability of the cardiac rhythm of a living being, said method comprising:

acquisition of an analogue cardiac signal of the living being;

sampling of using an analog-to-digital converter to sample said cardiac signal and construct of an RR series consisting of a plurality of samples, each sample representing the time intervals that separate two successive heart beats or the inverse of said time intervals; and

processing of the RR series using a processing unit by selecting samples in a main time window having a predetermined length of time, cutting said main window into subwindows, calculating an intermediary parameter for each subwindow on the basis of the samples contained in the subwindow, and calculating a final parameter as a function of the intermediary parameters.

16. Method according to claim 15 for the assessment of the pain felt by a living being, the final calculated parameter characterising the level of pain.

17. Method according to claim 15 for the assessment of the stress felt by a living being, the final calculated parameter characterising the level of stress.