METHOD AND APPARATUS FOR MONITORING BRAIN ACTIVITY

• US 20100305456A1
• Filed: 05/29/2009
• Published: 12/02/2010
• Est. Priority Date: 05/29/2009
• Status: Active Grant

• Current Assignee: Atlantis Limited Partnership
• Original Assignee: Atlantis Limited Partnership
• Inventors: Brainard, Edward C. II
• Granted Patent: US 8,460,196 B2
• Time in Patent Office: Days
• US Class Current: 600/483
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/165 Evaluating the state of mind, e.g. depression, anxiety
• CPC Class Codes: A61B 5/6816 Ear lobe

Abstract

Method for monitoring brain activity. Left and right cardiac pulse signals are detected at bilateral locations on a body for a selected number of cardiac cycles. Computing apparatus computes the standard deviation of the left and right pulse signals for the selected number of cardiac cycles. The standard deviations are normalized on the computing apparatus by dividing the left and right standard deviations by the mean of the left and right pulse signals computed over the selected number of cardiac cycles to produce a left and a right Coefficient of Variation of the pulse signals. A Bilateral Pulse Index is generated from the left and right Coefficients of Variation. The Bilateral Pulse Index relates to brain activity. Cardiac pulse signals from a single location on the body may be utilized in some embodiments.

Claims

1. Method for monitoring brain activity comprising:

detecting with a sensor cardiac pulse signals at a location on a body for a selected number of cardiac cycles;

computing on computing apparatus the variance or standard deviation of the pulse signals for the selected number of cardiac cycles;

processing the variance or standard deviation of the pulse signals to produce a coefficient of variation of the pulse signals; and

generating a pulse index from the coefficient of variation, wherein the pulse index relates to brain activity.

7. The method of claim 1, 2 or 3 wherein the brain activity is the sleep state.

8. The method of claim 1, 2 or 3 wherein the brain activity is awareness under anesthesia.

9. The method of claims 1, 2 or 3 wherein the pulse signals are detected by flesh penetrating electromagnetic radiation sensors.

10. The method of claims 1, 2, or 3 wherein the pulse signals are detected by plethysmographic or oximeter sensors.

11. The method of claims 1, 2, or 3 wherein suitable sensors are selected from the group consisting of optical sensors, RF displacement sensors, capacitance displacement sensors, pressure sensors, acoustic distance sensors, acoustic doppler flow sensors, optical displacement sensors, and ear canal sensors.

12. The method of claims 1, 2, or 3 wherein the sensors are connected to the computing apparatus by highly flexible cables to limit the introduction of motion artifacts during movement.

13. The method of claim 1, 2, or 3 wherein the sensors form a two-channel instrument.

14. The method of claim 1, 2, or 3 wherein the sensors do not include smoothing and balancing of the pulse data.

15. The method of claim 1, 2, or 3 including broadband processing in the range of 0.0 Hz to 50 Hz.

16. The method of claims 1, 2, or 3 using any suitable method to measure a variable signal after the normalizing step.

2. Method for monitoring brain activity comprising:

detecting with a sensor or sensors left and right cardiac pulse signals at bilateral locations on a body for a selected number of cardiac cycles;

computing on computing apparatus the variance or standard deviation of the left and right pulse signals for the selected number of cardiac cycles;

normalizing on computing apparatus the variance or standard deviation of the left and right pulse signals to produce a left and right coefficient of variation (CV) of the pulse signals; and

generating a bilateral pulse index (BPI) by combining mathematically the left and right coefficients of variation, wherein the BPI relates to brain activity.

4. The method of claim 2 or 3 wherein the bilateral locations are left and right earlobes.

5. The method of claim 2 or 3 wherein the bilateral locations are left and right portions of a forehead.

6. The method of claim 2 or 3 wherein the bilateral locations are left and right carotid arteries at the neck.

3. Method for monitoring brain activity comprising:

detecting with a sensor or sensors left and right cardiac pulse signals at bilateral locations on a body for a selected number of cardiac cycles;

computing on computing apparatus the standard deviation of the left and right pulse signals for the selected number of cardiac cycles;

normalizing on the computing apparatus the standard deviation of the left and right pulse signals by dividing the left and right standard deviations by the mean of the left and right pulse signals, respectively, computed over the selected number of cardiac cycles to produce a left and a right Coefficient of Variation (CV) of the pulse signals; and

generating a Bilateral Pulse Index (BPI) from the left and right Coefficients of Variation according to the equation

BPI=((Left CV+Right CV)/2)+(Absolute (Left CV−

Right CV)),

wherein BPI relates to brain activity.