Assessment of sleep quality and sleep disordered breathing based on cardiopulmonary coupling
View Patent ↗An assessment of sleep quality and sleep disordered breathing is determined from cardiopulmonary coupling between two physiological data series. An R-R interval series is derived from an electrocardiogram (ECG) signal. The normal beats from the R-R interval series are extracted to produce a normal-to-normal interval series. The amplitude variations in the QRS complex are used to extract a surrogate respiration signal (i.e., ECG-derived respiration) associated with the NN interval series. The two series are corrected to remove outliers, and resampled. The cross-spectral power and coherence of the two resampled signals are calculated over a plurality of coherence windows. For each coherence window, the product of the coherence and cross-spectral power is used to calculate coherent cross-power. Using the appropriate thresholds for the coherent cross-power, the proportion of sleep spent in CAP, non-CAP, and wake and/or REM are determined. Coherent cross-power can be applied to differentiate obstructive from non-obstructive disease, and admixtures of the same.
1. A method of assessing sleep quality for a subject, wherein the method is performed in a computer-based system, comprising:
deriving a heart rate interval series and a respiration series from at least one physiological signal obtained from the subject;
calculating a measure of cardiopulmonary coupling, wherein the measure of cardiopulmonary coupling is computed based on the heart rate interval series and the respiration series; and
automatically evaluating the spectral characteristics of the measure of cardiopulmonary coupling to differentiate between an obstructive sleep disorder and a non-obstructive sleep disorder.
2. The method according to claim 1 , wherein said evaluating step comprises:
identifying at least one of a plurality of spectral peaks and broad coupling spectra to detect said obstructive sleep disorder.
3. The method according to claim 1 , wherein said evaluating step comprises:
identifying at least one of a single dominant frequency and a narrow spectral dispersion to detect said non-obstructive sleep disorder.
4. The method according to claim 1 , wherein said evaluating step is independent of polysomnogram scoring.
5. The method according to claim 1 , further comprising:
producing a graphical representation of said cardiopulmonary coupling.
6. The method according to claim 5 , further comprising:
automatically evaluating said graphical representation to detect a CAP state, a non-CAP state, a wake state, or an REM state.
7. The method according to claim 5 , wherein 30-second epochs are applied to the graphical representation to thereby detect a CAP state, a non-CAP state, a wake state, or an REM state.
8. The method according to claim 5 further comprising:
automatically evaluating the graphical representation of said cardiopulmonary coupling to detect at least one of an aging or pathological condition.
9. The method according to claim 1 , further comprising:
automatically determining an effect of a drug or non-pharmacologic intervention.
10. The method according to claim 1 , further comprising:
automatically determining an adverse or therapeutic effect of a drug or non-pharmacologic intervention.
11. The method according to claim 1 , wherein the respiration series is derived from an electrocardiogram signal.
12. The method according to claim 1 , wherein the heart rate series and the respiration series are each derived from different physiological signals.
13. The method according to claim 1 , wherein the physiological signal is obtained using an electrocardiogram.