Methods for real-time autonomic nervous system monitoring using total heart rate variability, and notched windowing

• US 7,529,579 B2
• Filed: 07/11/2005
• Issued: 05/05/2009
• Est. Priority Date: 07/09/2004
• Status: Expired due to Fees

• Current Assignee: Ansar, Inc., The Ansar Group Incorporated
• Original Assignee: Ansar, Inc.
• Inventors: Aysin, Benhur, Colombo, Joseph, Welch, Robert G.
• Primary Examiner(s): SCHAETZLE, KENNEDY
• Application Number:
  US11/178,714
• Publication Number:
  US 20060100534A1
• Time in Patent Office: 1,394 Days
• Field of Search: 600/513
• US Class Current: 600/513
• CPC Class Codes: A61B 5/02405 Determining heart rate variability
• 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 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
• CPC Class Codes: A61B 5/4035 Evaluating the autonomic nervous system
• CPC Class Codes: A61B 5/412 Detecting or monitoring sepsis
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: A61B 5/726 using Wavelet transforms

Abstract

The present invention is a method and apparatus for non-invasive, real-time monitoring of the autonomic nervous systems. The present invention allows for monitoring of the autonomic nervous system using spectral analysis of both heart rate and respiratory signals. A preferred embodiment uses short-time Fourier transform (STFT) with a novel modified Bartlett windowing scheme in real-time so that the dynamic interactions between the sympathetic and parasympathetic divisions of the autonomic nervous system can be independently monitored. In addition, a preferred embodiment of the present invention uses the same techniques to monitor other biological or physiological data, including continuous blood pressure.

Claims

1. A method for power spectral analysis of heart rate variability comprising the steps of:

capturing a sample set of spline-interpolated heartbeat EKG signals;

applying a modified Bartlett window to a waveform of the captured sample set;

subjecting the windowed waveform to short-time Fourier transform (STFT); and

isolating a respiratory frequency area (RFA) from a low frequency area (LFA).

2. A method as set forth in claim 1, in which said short-time Fourier transform step comprises clinically suppressing mid-range heart rate variability frequencies and accentuating the low-and high-heart rate variability frequency ranges.

3. A method as set forth in claim 2, in which said step to clinically suppress comprises separating and isolating the parasympathetic and sympathetic frequencies of autonomic nervous system function;

thereby providing independent, non-invasive, repeatable, digital measures of parasympathetic and sympathetic activity levels.

4. A method as set forth in claim 2, in which said step to clinically suppress comprises monitoring parasympathetic and sympathetic activity to detect the early onset of sepsis, organ failure, and acute respiratory distress syndrome and other life threatening acute and critical care diseases.

5. A method as set forth in claim 2, in which said step to clinically suppress comprises monitoring parasympathetic and sympathetic activity for the early identification of mortality and morbidity of severely or injured patients who may need alternate therapy to promote survival.