Measurement method and measurement apparatus for bioelectric impedance and health management guideline advising apparatus comprising the measurement apparatus

• US 20030176808A1
• Filed: 03/13/2003
• Published: 09/18/2003
• Est. Priority Date: 09/19/2000
• Status: Active Grant

• Current Assignee: Physion Company Limited
• Original Assignee: Physion Company Limited
• Inventors: Masuo, Yoshihisa
• Granted Patent: US 7,203,536 B2
• Time in Patent Office: Days
• US Class Current: 600/547
• CPC Class Codes: A61B 2562/0215 Silver or silver chloride containing
• CPC Class Codes: A61B 2562/043 in a linear array
• CPC Class Codes: A61B 5/0537 Measuring body composition by impedance, e.g. tissue hydration or fat content
• CPC Class Codes: A61B 5/274 using snap or button fasteners
• CPC Class Codes: A61B 5/303 Patient cord assembly, e.g. cable harness
• CPC Class Codes: A61B 5/4872 Body fat
• CPC Class Codes: A61B 5/6824 Arm or wrist
• CPC Class Codes: A61B 5/6828 Leg

Abstract

The present invention aims to measure easily and accurately information about the panniculus (such as fatty layer, muscular layer, osseous layer) in the depth direction below the surface of a living body. To achieve this object, in an embodiment of the invention, a pair of current-carrying electrodes 1a, 1b and a pair of measuring electrodes 2a, 2b are rectilinearly arranged on the surface of the living body so that the measuring electrode 2a within a small area is placed very close to the current-carrying electrode 1a with small area. While constant current from a radio frequency current source 3 flows between the current-carrying electrodes 1a, 1b, the voltage between the measuring electrodes 2a, 2b is measured by the detector 4. The potential of the measuring electrode 2a is almost equal to the potential at the contact position P3 of the current-carrying electrode 1a, and the potential of the measuring electrode 2b is almost equal to the potential at the deepest position P1 of the vertical part 5c inside the living body 5. Therefore, the potential difference between the upper and lower ends of the vertical part 5c. The bioelectical impedance Zv of the vertical part 5c is calculated from the potential difference and the current i.

Claims

1. A bioelectrical impedance measurement method for measuring a bioelectrical impedance relating to information about an inside of a living body from an electrical signal measured on a surface of the living body, comprising steps of:

attaching a set of current-carrying electrodes including a first electrode having a small contact area and a second electrode to the surface of the living body set apart from each other by predetermined distances to generate a flow of radio frequency current inside the living body;

measuring a potential difference generated with the radio frequency current between a first part dose to the first electrode on the surface of the living body and a second part away from the first part by a distance equal to or greater than a preset distance; and

calculating the bioelectrical impedance in a depth direction below a contact part of the first electrode and its proximity, based on the potential difference and a value of the radio frequency current.

3. The bioelectrical impedance measuring method or measurement pparatus according to claim 1 or 2, characterized in that the measurement of the potential difference is a process of obtaining a voltage between the first measuring electrode attached to the first part and the second measuring electrode attached to the second part on the surface of the living body.

4. The bioelectrical impedance measuring method or measurement apparatus according to claim 1 or 2, characterized in that the measurement of the potential difference is a process using a reference electrode provided at a third part on the surface of the living body away from the first part and the second part, including steps of measuring the voltage between the fist part and the third part and the voltage between the second part and the third part, and calculating the voltage difference between the two voltages.

7. The bioelectical impedance measuring method or measurement apparatus according to one of claims 1-6, characterized in that the current-carrying electrodes and the measuring electrodes are almost linearly arranged on the surface of the living body.

8. The bioelectrical impedance measurement method or measurement apparatus according to claim 3, characterized in that:

the first and second current-carrying electrodes and the first and second measuring electrodes are almost linearly arranged on the surface of the living body, the first measuring electrode is placed close to the first current-carrying electrode on an extension of a straight line drawn between the first current-carrying electrode and the second current-carrying electrode, and the second measuring electrode is placed away from the fist measuring electrode at a distance almost equal to the distance between the first current-carrying electrode and the second current-carrying electrode;

a fist measurement is performed for measuring a voltage between the first measuring electrode and the second measuring electrode while supplying a current into the living body through the first current-carrying electrode and the second current-carrying electrode;

a second measurement is performed for measuring a voltage between the first current-carrying electrode and the second current-carrying electrode while supplying a current into the living body through the first measuring electrode and the second measuring electrode; and

an accuracy of calculating the bioelectrical impedance in the depth direction below the first current-carrying electrode and its proximity, and below the first measuring electrode and its proximity is improved by using results of the first measurement and the second measurement.

9. The bioelectrical impedance measurement method or measurement apparatus according to claim 3, characterized in that:

the first and second current-carrying electrodes and the first and second measuring electrodes are almost rectilinearly arranged on the surface of the living body, the first measuring electrode is placed close to the first current-carrying electrode on an extension of a straight line drawn between the first current-carrying electrode and the second current-carrying electrode, and the second measuring electrode is placed away from the first measuring electrode by a distance almost equal to a distance between the first current-carrying electrode and the second current carrying electrode;

a first measurement is performed for measuring a voltage between the first measuring electrode and the second measuring electrode while supplying a current into the living body through the first current-carrying electrode and the second current-carrying electrode;

a second measurement is performed for measuring a voltage between the first current-carrying electrode and the second current-carrying electrode while supplying a current into the living body through the first measuring electrode and the second measuring electrode; and

a difference between the bioelectrical impedances in a horizontal direction at a depth below or nearly below and between the first current-carrying electrode and second current-carrying electrode, and that below or nearly below and between the first measuring electrode and second measuring electrode is calculated, using results of the first measurement and the second measurement.

10. The bioelectrical impedance measurement method or measurement apparatus according to one of claims 1-3 and 7, characterized in that one or more additional measuring electrodes are arranged between the fast measuring electrode and the second measuring electrode and voltages between these electrodes are measured to measure the bioelectrical impedances of regions at different positions in the depth direction below or nearly below the contact part of the fist current-carrying electrode.

11. The bioelectical impedance measurement method or measurement apparatus according to one of claims 1-3 and 7, characterized in that one or more additional measuring electrodes are arranged between the first measuring electrode and the second measuring electrode, and an electrode for supplying the current and an electrode for measuring the voltage are shifted step by step within said one or more additional electrodes to measure a distribution of the bioelectrical impedance in the depth direction below or nearly below and between the first measuring electrode and the second measuring electrode.

12. The bioelectrical impedance measurement method or measurement apparatus according to one of claims 2-4 and 6-11, characterized in that the current-carrying electrodes and the measurement electrodes are formed on one side of a sheet-like member, and the sheet-like member is affixed to the surface of the living body to perform a measurement.

13. A health management guideline advising apparatus using the bioelectrical impedance measurement apparatus according to one of claims 24 and 6-11, comprising:

a body composition estimating means for estimating information about a body composition of a subject based on a measurement value of the bioelectrical impedance in the depth direction;

a displaying means for displaying the information about the body composition

14. The health management guideline advising apparatus according to claim 13, characterized in that the current-carrying electrodes and the measuring electrodes are arranged on a side to be closely brought into contact with the living body, and the radio frequency current supplying means, the voltage measuring means, the calculating means and the body composition estimating means are enclosed in a box-shaped body having said side as one of its sides, and a display part of the displaying means is provided on a side other than said side to be contacted to the living body.

15. The health management guideline advising apparatus according to claim 13 or 14, characterized in that the body composition measuring means is a means for estimating a thickness of a subcutaneous fat layer of the subject based on the measurement value of the bioelectrical impedance, and the display means is a means for displaying an estimated fat thickness.

16. A health management guideline advising apparatus using the bioelectrical impedance measurement apparatus according to one of claims 24 and 6-11, comprising:

a main measuring means for generating a current flow inside the limbs and/or the trunk in a longitudinal direction thereof through plural electrodes affixed to a predetermined part of the body surface of a subject, and for measuring a voltage between electrodes affixed at a part predetermined inside to measure the bioelectrical impedance in a longitudinal direction; and

a body composition estimating means for estimating a body composition of the subject based on a value of the bioelectrical impedance measured by the main measuring means, body specification information and a value of the bioelectrical impedance in the depth direction of the living body measured by the bioelectrical impedance measurement apparatus.

17. The health management guideline advising apparatus according to claim 16, characterized in that at least some of the plural electrodes of the main measuring means are shared with the current-carrying electrodes or the measuring electrodes.

2. A bioelectrical impedance measurement apparatus for measuring a bioelectrical impedance relating to information about an inside of a living body from an electrical signal measured on a surface of the living body, comprising:

a) a set of current-carrying electrodes to be attached to the surface of the living body set apart from each other by predetermined distances, including a first electrode having a small contact area to generate a concentrated flow of current with high density, and a second electrode;

b) a radio frequency current supplying means for generating a flow of radio frequency current inside the living body through the first and second current-carrying electrodes;

c) measuring electrodes attached to the surface of the living body, including a first electrode located close to a contact part of the first current-carrying electrode and a second electrode located away from the first measuring electrode at a distance equal to or greater than a preset distance;

d) a voltage measuring means for measuring a potential difference generated with the radio frequency current between the first and second measuring electrodes; and

e) a calculating means for calculating the bioelectrical impedance in a depth direction below the contact part of the first current-carrying electrode and its proximity, based on the potential difference and a value of the radio frequency current.

5. A bioelectrical impedance measurement method for measuring bioelectrical impedance relating to information about an inside of a living body from an electrical signal measured on a surface of the living body, having:

a first measurement mode where a set of current-carrying electrodes including a first electrode with a small contact area and a second electrode are attached to the surface of the living body set apart from each other at predetermined distances to generate a flow of radio frequency current in the living body between the first electrode and the second electrode; and

a second measurement mode where a flow of radio frequency current is generated between the second electrode and a third electrode attached to the surface of the living body on an extension of a straight line drawn between the first electrode and the second electrode, where the extension is made beyond the first electrode,

and the method comprises steps of;

measuring a voltage on the surface of the living body between a proximity of the first electrode and a contact part of the second electrode or its proximity for each of the first and second measurement modes, and calculating a voltage difference between the two modes; and

calculating the bioelectrical impedance in a depth direction below the contact part of the fist electrode and its proximity, based on the voltage difference and the value of the radio frequency current.

6. A bioelectrical impedance measurement apparatus for measuring a bioelectrical impedance relating to information about an inside of a living body from an electrical signal measured on a surface of the living body, which includes:

a) a set of current-carrying electrodes to be attached to the surface of the living body set apart from each other by predetermined distances, including a first current-carrying electrode with a small contact area, a second current-caring electrode, and a third current-carrying electrode attached to the surface of the living body on an extension of a straight line drawn between the first current-carrying electrode and the second electrode, where the extension is made beyond the first current-carrying electrode;

b) a radio frequency current supplying means for generating a flow of radio frequency current in the living body between the first current-carrying electrode and the second current-carrying electrode in a fist measurement mode, and for generating a flow of radio frequency current in the living body between the second current-carrying electrode and the third current caring electrode in a second measurement mode;

c) measuring electrodes including a first measuring electrode attached close to the first current-carrying electrode on the surface of the living body, and a second measuring electrode attached to a contact part of the second current-carrying electrode or in a proximity of the contact part;

d) a voltage measuring means for measuring a voltage between the first measuring electrode and the second measuring electrode for each of the first and second measurement mode, and for calculating a voltage difference between the two modes; and

e) a calculating means for calculating the bioelectrical impedance in a depth direction below a contact part of the fist current-carrying electrode and its proximity, based on the voltage difference and the value of the radio frequency current.