Method and apparatus for ECG derived sleep monitoring of a user

• US 20050148895A1
• Filed: 12/22/2004
• Published: 07/07/2005
• Est. Priority Date: 01/06/2004
• Status: Abandoned Application

• Current Assignee: Dale Julian Misczynski, Vladislav Bukhman
• Original Assignee: Dale Julian Misczynski, Vladislav Bukhman
• Inventors: Bukhman, Vladislav, Misczynski, Dale Julian
• Application Number:
  US11/020,953
• Publication Number:
  US 20050148895A1
• Time in Patent Office: Days
• US Class Current: 600/513
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/4035 Evaluating the autonomic nervous system
• CPC Class Codes: A61B 5/4809 Sleep detection, i.e. determining whether a subject is asleep or not
• CPC Class Codes: A61B 5/4812 Detecting sleep stages or cycles
• CPC Class Codes: A61B 5/6831 Straps, bands or harnesses
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: A61B 5/726 using Wavelet transforms

Abstract

The invention relates to a method and device for simultaneous monitoring of cardiac activity, respiratory rate, and the evaluation of sleep states of a user. The invention comprises a seamless on-line evaluation of cardiac activity, heart rate variability, and ECG derived respiratory rate and using these data as an input for evaluation and quantitative assessment of sleep disorders. The hardware comprises of a flexible cardiac belt with 3 electrodes, which is easy to use without involvement of trained professionals.

Claims

1. A method of assessing the cardiac, respiratory and sleep activity of a user comprising:

a) Placing a plurality of electrodes on said user'"'"'s torso;

b) Acquiring an ECG using at least one of said electrodes;

c) Identifying one or more characteristic points on said ECG;

d) Determining respiratory rate using R-waves of said acquired ECG;

e) Measuring parameters using at least one of said one or more characteristic points on said ECG; and

f) Measuring heart rate variability using said measured parameters of said ECG;

g) Evaluation of sympathetic and parasympathetic activity of autonomic nervous system using said measured heart rate variability;

h) Assessment of sleep stages of a user using power spectrum analysis of said sympathetic and parasympathetic activity.

2. The method of claim 1, wherein said plurality of electrodes comprise two sensing electrodes and one reference electrode positioned substantially parallel to the subclavian artery where sensing electrode are positioned in a close proximity to midaxillary lines at nipples level.

3. The method of claim 2, wherein said sensing electrodes are placed in a stretchable strap.

4. The method of claim 1, wherein said step of identifying one or more characteristic points on said ECG entails identifying at least one of the following points:

R, Q, S, J, T and T_e.

5. The method of claim 1, wherein said characteristic points are used for measurement of cardiac parameters.

6. The method of claim 1, wherein said respiratory rate is measured using fluctuation of the amplitude of R wave of said ECG.

7. The method of claim 1, wherein power spectrum analysis is used for determining of said sleep stages.

8. The method of claim 1, wherein Fast Fourier Transform (FFT) algorithm applied for calculation of low frequency (LF), reflecting both sympathetic and parasympathetic activities, and high frequency (HF), reflecting parasympathetic activity.

9. The method of claim 8, wherein total power (TP), said LF activity power (LP), and said HF activity power are calculated for the first 5 minutes of monitoring using said FFT algorithm.

10. The method of claim 8, wherein the wakefulness signature level WS is calculated by:

11. The method of claim 8, wherein current said wakefulness level W_c is calculated in 5 minutes window with 30 second shift by:

12. The method of claim 8, wherein in order to determine said sleep stages said current wakefulness level is compared with said wakefulness signature level.

13. The method of claim 8, wherein if said W_c≦

0.75*W_s, (i.e. ratio of sympathetic activity to parasympathetic activity drops by equal or more then 25% during the last 5 minutes), then the user is considered in NREM sleep state.

14. The method of claim 8, wherein if said W_c increases by more than 15% and said LP doesn'"'"'t change and the previous record shows that the user was in NREM stage, then the user is considered in REM sleep state.

15. The method of claim 8, wherein if said W_c increases by more than 15% and LP increases and the previous record shows that the user was in NREM or REM sleep, then the user is considered in the after-sleep wakefulness state.