DEVICES AND METHODS FOR MONITORING CEREBRAL HEMODYNAMIC CONDITIONS

• US 20120203091A1
• Filed: 10/03/2011
• Published: 08/09/2012
• Est. Priority Date: 02/09/2011
• Status: Active Grant

• Current Assignee: Orsan Medical Technologies, Ltd.
• Original Assignee: Orsan Medical Technologies, Ltd.
• Inventors: Kinrot, Opher, Ben-Ari, Shlomi, Radai, Michael
• Granted Patent: US 9,345,411 B2
• Time in Patent Office: Days
• US Class Current: 600/383
• CPC Class Codes: A61B 5/0265 using electromagnetic means, e.g. electromagnetic flowmeter
• CPC Class Codes: A61B 5/0295 using plethysmography, i.e. measuring the variations in the volume of a body part as modified by the circulation of blood therethrough, e.g. impedance plethysmography
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/0535 Impedance plethysmography for measuring blood flow A61B5/0295
• CPC Class Codes: A61B 5/4064 Evaluating the brain A61B5/031, A61B5/369, A61B5/14553 take precedence
• CPC Class Codes: A61B 5/6803 Head-worn items, e.g. helmets, masks, headphones or goggles
• CPC Class Codes: A61B 5/6814 Head
• CPC Class Codes: A61B 5/7246 using correlation, e.g. template matching or determination of similarity

Abstract

Devices, and methods for measuring bioimpedance signals are disclosed. One aspect may include a headset apparatus including a retainer and electrodes. The retainer may be configured to position the electrodes on the head of a subject so as to obtain bioimpedance signals indicative of hemodynamic conditions associated with an MCA territory. A processor may be included to measure and analyze the obtained bioimpedance signals, and to output information for predicting hemodynamic conditions associated with an MCA territory.

Claims

1. A headset apparatus, comprising:

a retainer;

a first electrode connected to the retainer at a first position such that when the retainer is oriented on a head of a subject, the first electrode is located anterior to an MCA of the subject and generally opposes an anterior horn of a lateral cerebral ventricle;

a second electrode connected to the retainer at a second position, such that when the retainer is oriented on the head of the subject, the second electrode is located posterior to the MCA and generally opposes a posterior horn of the lateral cerebral ventricle; and

at least one electrical conductor enabling the first electrode and the second electrode to be connected in a circuit, such that when the first electrode is in the first position and the second electrode is in the second position and the first and second electrodes are connected to a circuit through which current flows, the retainer, the first electrode, and the second electrode cooperate to enable current to flow from one of the first and second electrodes on one side of the MCA through the lateral cerebral ventricle and to another of the first and second electrodes on a second side of the MCA, opposite the first side.

2. The headset apparatus of claim 1, wherein the retainer maintains a spacing of between 70 mm and 100 mm between the first electrode and the second electrode.

3. The headset apparatus of claim 1, wherein the retainer maintains a spacing of between 75 and 95 mm between the first electrode and the second electrode.

4. The headset apparatus of claim 1, wherein the retainer positions the first and second electrodes according to a sensitivity map.

5. The headset apparatus of claim 1, wherein the retainer positions the first electrode to be glued to exposed skin on the forehead and positions the second electrode to be glued to exposed skin above the ear.

6. The headset apparatus of claim 1, wherein the retainer positions the first and second electrodes such that the first and second electrodes are not directly above external blood vessels or muscled areas.

7. The headset apparatus of claim 1, wherein the electrodes are oriented to enable current to pass from the first electrode, through the lateral cerebral ventricle and to the second electrode.

8. The headset apparatus of claim 1, further comprising a third electrode connected to the retainer at a third position and a fourth electrode connected to the retainer at a fourth position, such that when the retainer is oriented on the head of the subject, the third electrode is located on a side of the head opposite to the first electrode, and the fourth electrode located on a side of the head opposite the second electrode, and wherein the third and fourth electrodes are paired such that current associated with the first and second electrodes is enabled to flow through a first lateral cerebral ventricle, and current associated with the third and fourth electrodes is enabled to flow through a second lateral cerebral ventricle, opposite the first lateral cerebral ventricle.

9. The headset apparatus of claim 1, further comprising at least one processor configured to measure at least one bioimpedance signal from the current that flows from one of the first and second electrodes to another of the first and second electrodes.

10. The headset apparatus of claim 9, wherein the at least one processor is further configured to output information for predicting a hemodynamic condition associated with an MCA territory on a side of the head of the subject on which the first and second electrode are positioned based on the at least one bioimpedance signal.

11. The headset apparatus of claim 8, further comprising at least one processor configured to measure at least one bioimpedance signal from the current associated with the first and second electrodes and at least one other bioimpedance signal from the current associated with the third and fourth electrodes.

12. The headset apparatus of claim 11, wherein the at least one processor is further configured to output information for predicting a hemodynamic condition of an MCA territory associated with a side of the head of the subject on which the first and second electrodes are positioned based on the at least one bioimpedance signal, and for predicting a hemodynamic condition associated with an MCA territory on a side of the head of the subject on which the third and fourth electrode are positioned based on the at least one other bioimpedance signal.

13. The headset apparatus of claim 1, wherein the first and second electrodes are configured to drive current therebetween and to enable measurement of a resulting voltage.

14. The headset apparatus of claim 1, wherein the first electrode is a first current electrode and the second electrode is a second current electrode, and wherein the headset apparatus further includes a first voltage electrode and a second voltage electrode, wherein the first and second voltage electrodes are respectively located on the retainer at positions adjacent to the first and second current electrodes.

15. A method for predicting a hemodynamic condition associated with an MCA territory, the method comprising:

positioning a first electrode at a first position on a head of a subject, such that the first electrode is located anterior to an MCA of the subject and generally opposes an anterior horn of a lateral cerebral ventricle;

positioning a second electrode at a second position on the head of the subject, such that the second electrode is located posterior to the MCA and generally opposes a posterior horn of the lateral cerebral ventricle;

driving a current between the first electrode and the second electrode;

measuring a bioimpedance signal that results from driving the current; and

outputting information for predicting a hemodynamic condition associated with the MCA territory on a side of the head on which the first and second electrodes are positioned, based on the bioimpedance signal.

16. The method of claim 15, wherein the first and second electrode are attached to a retainer configured to position the first and second electrodes in a predetermined orientation on the head of the subject.

17. The method of claim 15, wherein during driving, the retainer maintains a spacing of between 70 mm and 100 mm between the first electrode and the second electrode.

18. The method of claim 15, wherein during driving, the retainer maintains a spacing of between 70 and 95 mm between the first electrode and the second electrode.

19. The method of claim 15, wherein, during driving, the retainer maintains positioning of the first and second electrodes according to a sensitivity map.

20. The method of claim 15, wherein, positioning the first electrode further comprises gluing the first electrode to exposed skin on the forehead and positioning the second electrode further comprises gluing the second electrode to exposed skin above the ear.

21. The method of claim 15, wherein the first and second positions are not directly above external blood vessels or muscled areas.

22. The method of claim 15, further comprising orienting the electrodes to enable current to pass from the first electrode, through the lateral cerebral ventricle and to the second electrode.

23. The method of claim 15, further comprising orienting the first and second electrodes to cause current to concentrate in a generally wedge-shaped region having a wedge apex generally intersecting the anterior horn of the lateral cerebral ventricle and a wedge base generally oriented toward the subject'"'"'s skull.[see comment to claim 6]

24. The method of claim 15, further comprising positioning a third electrode at a third position on the head of the subject, such that the third electrode is located on a side of the head opposite the first electrode, positioning a fourth electrode at a fourth position on the head of the subject, such that the fourth electrode is located on the side of the head opposite the second electrode;

driving a second current between the third electrode and the fourth electrode;

measuring a second bioimpedance signal that results from driving the second current; and

outputting information for predicting a hemodynamic condition associated with an MCA territory on a side of the head on which the third and fourth electrodes are positioned, based on the second bioimpedance signal.