APPARATUS FOR MEASURING BLOOD VOLUME AND METHOD OF EVALUATING RESULT OF MEASUREMENT BY APPARATUS FOR MEASURING BLOOD VOLUME

• US 20100268518A1
• Filed: 04/16/2010
• Published: 10/21/2010
• Est. Priority Date: 04/17/2009
• Status: Active Grant

• Current Assignee: Nihon Kohden Corporation
• Original Assignee: Nihon Kohden Corporation
• Inventors: SUGO, Yoshihiro
• Granted Patent: US 8,535,234 B2
• Time in Patent Office: Days
• US Class Current: 703/2
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/0285 Measuring or recording phase velocity of blood waves
• CPC Class Codes: A61B 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence

Abstract

An apparatus for measuring a blood volume, includes: a first calculator which calculates a first blood volume by using information on a cardiac output of a subject; and a second calculator which calculates a second blood volume by using information on oxygen metabolism of the subject.

Claims

1. An apparatus for measuring a blood volume, the apparatus comprising:

a first calculator which calculates a first blood volume by using information on a cardiac output of a subject; and

a second calculator which calculates a second blood volume by us ing information on oxygen metabolism of the subject.

2. The apparatus according to claim 1, wherein

the second calculator receives the specific information and calculates the oxygen metabolism, and calculates the second blood volume based on the calculated oxygen metabolism, and the first calculator calculates the first blood volume based on a pulse wave propagation time and a heart rate of the subject, from an expression of CO=(α

K·

PWTT+β

K) ·

HR where CO is the first blood volume, PWTT is the pulse wave propagation time, HR is the heart rate, and α

K and β

K are coefficients inherent to the subject.

3. The apparatus according to claim 2, wherein the specific information includes at least a sex, age, body surface area, blood pressure of the subject, and the heart rate.

4. The apparatus according to claim 3, wherein the specific information further includes one of the pulse wave propagation time and a pulse wave velocity.

5. The apparatus according to claim 2, further comprising:

an evaluator which compares the first blood volume and the second blood volume and evaluates and displays a blood volume calculation function based on comparison result.

6. The apparatus according to claim 5, wherein the blood volume calculating function is evaluated based on a difference of change rates of the first and second blood volumes which are calculated from a reference time to a calculation time when the first and second calculators calculates the first and second blood volumes.

7. An apparatus for measuring a blood volume, the apparatus comprising:

a first calculator which calculates a first blood volume by using information on a cardiac output of a subject; and

a third calculator which calculates a third blood volume from a change amount of a demand of a blood volume from a reference time to a time, the change amount being estimated by using information on a cardiac output and oxygen metabolism of the subject at the reference time.

8. The apparatus according to claim 7, wherein the third calculator calculates the third blood volume by using a blood pressure and a heart rate of the subject.

9. The apparatus according to claim 8, wherein the third calculator further calculates the third blood volume by using a pulse wave propagation time of the subject.

10. The apparatus according to claim 8, wherein the third calculator calculates the third blood volume based on an expression of CO=CO1+e1·

(HR·

PP−

HR0·

PP0) where CO is the third blood volume, CO1 is the cardiac output at the reference time, HR is the heart rate, HR0 is HR at the reference time, PP is the blood pressure, PP0 is PP at the reference time, and e1 is a constant.

11. The apparatus according to claim 9, wherein the third calculator calculates the third blood volume based on an expression of CO=CO1+e1·

(HR·

PP−

HR0·

PP0)+f1·

(PWTT−

PWTT0) where CO is the third blood volume, CO1 is the cardiac output at the reference time, HR is the heart rate, HR0 is HR at the reference time, PP is the blood pressure, PP0 is PP at the reference time, PWTT is the pulse wave propagation time, PWTT0 is PWTT at the reference time, and e1 and f1 are constants.

12. The apparatus according to claim 7, further comprising:

an evaluator which compares the first blood volume and the third blood volume and evaluates and displays a blood volume calculation function based on comparison result.

13. The apparatus claim 12, wherein the blood volume calculation function is evaluated based on a difference of change rates of the first and third blood volumes which are calculated from the reference time to an estimation time when the first and third calculators calculates the first and third blood volumes.

14. A method of evaluating a result of measurement of a blood volume by an apparatus for measuring the blood volume, the method comprising:

inputting at least a sex, an age, a body surface area, a blood pressure, and a heart rate as specific information of a subject;

calculating oxygen metabolism relating to a cardiac output of the subject and calculating a second blood volume based on the calculated oxygen metabolism;

calculating a first blood volume based on a pulse wave propagation time and the heart rate, from an expression of CO=(α

K·

PWTT+β

K)·

HR where CO is the first blood volume, PWTT is the pulse wave propagation time, HR is the heart rate, and α

K and β

K are coefficients inherent to the subject; and

performing evaluation based on a difference of change rates of the first and second blood volumes which are calculated from a reference time to an estimation time when the first and second blood volumes are calculated.

15. The method according to claim 14, wherein the second blood volume is calculated by an expression of CO2=a1+b1·

Sex+c1·

Age+d1·

BSA+e1·

HR·

PP where CO2 is the second blood volume;

Sex is the sex, when the subject is male, Sex=1, and when the subject is female, Sex=−

1;

Age is the age;

BSA is the body surface area;

HR is the heart rate;

PP is the blood pressure; and

a1, b1, c1, d1, and e1 are constants.

16. The method according to claim 14, wherein the second blood volume is calculated by an expression of CO2=a2+b2·

Sex+c2·

Age+d2·

BSA+e2·

HR·

PP+f2·

PWTT where CO2 is the second blood volume;

Sex is the sex, when the subject is male, Sex=1, and when the subject is female, Sex=−

1;

Age is the age;

BSA is the body surface area;

HR is the heart rate;

PP is the blood pressure;

PWTT is a pulse wave propagation time of the subject; and

a2, b2, c2, d2, e2, and f2 are constants.

17. A computer-readable recording medium in which a computer program causing the apparatus to execute the method according to claim 14 is recorded.