BLOOD VOLUME MEASURING METHOD AND BLOOD VOLUME MEASURING APPARATUS

• US 20110060531A1
• Filed: 09/09/2010
• Published: 03/10/2011
• Est. Priority Date: 09/08/2009
• Status: Active Grant

• Current Assignee: Nihon Kohden Corporation
• Original Assignee: Nihon Kohden Corporation
• Inventors: HYOGO, Mitsushi, SUGO, Yoshihiro
• Granted Patent: US 9,282,906 B2
• Time in Patent Office: Days
• US Class Current: 702/19
• CPC Class Codes: A61B 5/02255 the pressure being controlled by plethysmographic signals, e.g. derived from optical sensors
• 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

A blood volume measuring method includes: acquiring data of stroke volume variation at each respiratory rate, and storing the acquired data in a first buffer; reading an N1 number of the data stored in the first buffer, from the first buffer, and storing the N1 number of the data in a second buffer; excluding a part of the data stored in the second buffer, a value of each of which exceeds a first upper limit or falls below a first lower limit, from the data stored in the second buffer, and storing the other of the data stored in the second buffer, in a third buffer; acquiring a deviation of each of the data stored in the third buffer, from a median value of the data stored in the third buffer, excluding a part of the data stored in the third buffer, the deviation of each of which exceeds a second upper limit or falls below a second lower limit, from the data stored in the third buffer, and storing the other of the data stored in the third buffer, in a fourth buffer; determining whether N2/N1 is within an allowable value or not, wherein the N2 is a number of the data stored in the fourth buffer; and when it is determined that the N2/N1 is within the allowable value, calculating data of average stroke volume variation based on the data stored in the fourth buffer.

Claims

1. A blood volume measuring method comprising:

acquiring data of stroke volume variation at each respiratory rate, and storing the acquired data in a first buffer;

reading an N1 number of the data stored in the first buffer, from the first buffer, and storing the N1 number of the data in a second buffer;

excluding a part of the data stored in the second buffer, a value of each of which exceeds a first upper limit or falls below a first lower limit, from the data stored in the second buffer, and storing the other of the data stored in the second buffer, in a third buffer;

acquiring a deviation of each of the data stored in the third buffer, from a median value of the data stored in the third buffer, excluding a part of the data stored in the third buffer, the deviation of each of which exceeds a second upper limit or falls below a second lower limit, from the data stored in the third buffer, and storing the other of the data stored in the third buffer, in a fourth buffer;

determining whether N2/N1 is within an allowable value or not, wherein the N2 is a number of the data stored in the fourth buffer; and

when it is determined that the N2/N1 is within the allowable value, calculating data of average stroke volume variation based on the data stored in the fourth buffer.

2. The blood volume measuring method according to claim 1, wherein

the data of stroke volume variation are calculated by measuring variation of a pulse wave propagation time of a patient based on correlation between a stroke volume and the pulse wave propagation time.

3. The blood volume measuring method according to claim 2, wherein

the data of stroke volume variation are calculated by using an expression of

SVV=2·

(esSVmax−

esSVmin)/(esSVmax+esSVmin),

where SVV is stroke volume variation, esSVmax is maximum estimated stroke volume per respiratory rate, and esSVmin is minimum estimated stroke volume per respiratory rate.

4. The blood volume measuring method according to claim 1, wherein

the data of stroke volume variation are data of arterial pulsation pressure variation which are calculated by measuring a pulse pressure of a blood pressure of a patient based on correlation between a stroke volume and the blood pressure.

5. The blood volume measuring method according to claim 4, wherein

the data of arterial pulsation pressure variation are calculated by using an expression of

PPV=2·

(PPmax−

PPmin)/(PPmax+PPmin),

where PPV is arterial pulsation pressure variation, PPmax is maximum arterial pulsation pressure per mechanical respiratory rate, and PPmin is minimum arterial pulsation pressure per mechanical respiratory rate.

6. The blood volume measuring method according to claim 1, wherein

the data of stroke volume variation are data of pulse wave amplitude variation which are calculated by measuring a pulse wave amplitude of a patient based on correlation between a stroke volume and the pulse wave amplitude.

7. The blood volume measuring method according to claim 6, wherein

the data of pulse wave amplitude variation are calculated by an expression of

PAV=100·

(Pmax−

Pmin)/meanP,

where PAV is pulse wave amplitude variation, Pmax is maximum pulse wave amplitude per respiratoty rate, Pmin is minimum pulse wave amplitude per respiratoty rate, and meanP is average pulse wave amplitude per respiratoty rate.

8. A computer-readable recording medium in which a computer program causing a computer to execute the method according to claim 1 is recorded.

9. An blood volume measuring apparatus comprising:

a buffer in which data of stroke volume variation at each respiratory rate are stored; and

a controller;

excludes data each of which has an abnormal value from a predetermined number of the data of stroke volume variation;

excludes data each of which has an abnormal deviation from the data of stroke volume variation from which the data each of which has the abnormal value have been excluded;

acquires a ratio of a number of the data of stroke volume variation data from which the data each of which has the abnormal deviation have been excluded, to the predetermined number; and

performs calculation of data of an average stroke volume variation based on the data of stroke volume variation data from which the data each of which has the abnormal deviation have been excluded, when the ratio is within an allowable value.