Blood pressure estimating apparatus

• US 6,527,725 B1
• Filed: 01/25/2001
• Issued: 03/04/2003
• Est. Priority Date: 01/25/2001
• Status: Expired due to Fees

• Current Assignee: Omron Healthcare Company Limited (Omron Corporation)
• Original Assignee: Colin Corporation (Fukuda Denshi Company Limited)
• Inventors: Inukai, Hidekatsu, Yokozeki, Akihiro, Kawaguchi, Keizoh, Narimatsu, Kiyoyuki
• Primary Examiner(s): Nasser, Robert L.
• Application Number:
  US09/768,265
• Time in Patent Office: 768 Days
• Field of Search: 600/500, 600/485, 600/490, 600/493-6
• US Class Current: 600/485
• CPC Class Codes: A61B 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/02225 using the oscillometric method
• CPC Class Codes: A61B 5/0225 the pressure being controlled by electric signals, e.g. derived from Korotkoff sounds
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/0285 Measuring or recording phase velocity of blood waves

Abstract

An apparatus for estimating a blood pressure of a living subject, including a measuring device which iteratively measures a blood pressure of the subject, a first device for obtaining first information relating to velocity of propagation of pulse wave, a second device for obtaining at least one of second information relating to heart rate and third information relating to area defined by volume pulse wave, a memory which stores groups of information each group of which includes the blood pressure, the first information, and at least one of the second information and the third information, a determining device for determining an expression representing a relationship between (A) blood pressure, and (B1) first information and (B2) at least one of (B21) second information and (B22) third information, and having a first coefficient for the first information, at least one second coefficient for at least one of the second and third information, and a constant, the determining device determining the coefficients and constant of the expression by applying a multiple regression analysis to more than a predetermined number of groups of information last stored in the memory, the predetermined number being equal to a total number of the coefficients and the constant, and an estimating device for successively estimating, according to the expression, a blood pressure of the subject based on each first information and at least one of each second information and each third information.

Claims

1. An apparatus for successively estimating an intraarterial blood pressure of a living subject, based on information non-invasively obtained from a circulatory organ of the subject, comprising:

a blood-pressure measuring device which includes an inflatable cuff adapted to apply a pressing force to a body portion of the subject and iteratively measures, by changing the pressing force of the cuff, a blood pressure of the subject at a predetermined period;

a first means for non-invasively obtaining, from the circulatory organ of the subject, a set of first information which relates to a velocity of propagation of a pulse wave which propagates through an artery of the subject, at least each time the blood-pressure measuring device measures a blood pressure of the subject;

a second means for non-invasively obtaining, from the circulatory organ of the subject, at least one of a set of second information which relates to a heart rate of the subject and a set of third information which relates to an area defined by a volume pulse wave from a peripheral portion of the subject, at least each time the blood-pressure measuring device measures said blood pressure;

a first memory device which stores a plurality of groups of information each group of which comprises said blood pressure measured by the blood-pressure measuring device, the set of first information obtained by the first means when said blood pressure is measured by the blood-pressure measuring device, and said at least one of the set of second information and the set of third information obtained by the second means when said blood pressure is measured by the blood-pressure measuring device;

an expression determining means for determining an expression representing a relationship between (A) blood pressure, and (B1) first information and (B2) at least one of (B21) second information and (B22) third information, the expression having a first coefficient for the first information, at least one second coefficient for said at least one of the second information and the third information, and a constant, the expression determining means determining the first and second coefficients and the constant of the expression by applying a multiple regression analysis to more than a first predetermined number of said groups of information last stored in the first memory device, the first predetermined number being equal to a total number of the first coefficient, said at least one second coefficient, and the constant; and

a blood-pressure estimating means for successively estimating, according to the determined expression representing the relationship between (A) blood pressure, and (B1) first information and (B2) at least one of (B21) second information and (B22) third information, an intraarterial blood pressure of the subject, based on each of a plurality of sets of first information successively obtained by the first means and at least one of each of a plurality of sets of second information, and each of a plurality of sets of third information, successively obtained by the second means when said each of sets of first information is obtained by the first means.

2. An apparatus according to claim 1, wherein the expression determining means comprises means for determining the first and second coefficients and the constant of the expression by applying the multiple regression analysis to not more than a second predetermined number of said groups of information last stored in the first memory device, the second predetermined number being greater than the first predetermined number.

3. An apparatus according to claim 1, wherein the second means obtains the set of second information and the set of third information, and wherein the blood-pressure estimating means comprises means for estimating, according to the expression representing the relationship between (A) blood pressure, and (B1) first information, (B21) second information, and (B22) third information, the intraarterial blood pressure of the subject, based on said each set of first information obtained by the first means, and each set of second information and each set of third information obtained by the second means when said each set of first information is obtained by the first means.

4. An apparatus according to claim 3, wherein the first means comprises means for obtaining, as the set of first information, a time, DT, which is needed for the pulse wave to propagate between two different portions of the artery, wherein the second means comprises means for obtaining, as the set of second information, a heart-beat period, RR, of the subject, and means for obtaining, as the set of third information, a ratio, VR, of the area of the volume pulse wave to the heart-beat period RR, and wherein the blood-pressure estimating means comprises means for successively estimating, according to the expression representing the relationship between (A) blood pressure, EBP, and (B1) time DT, (B21) period RR, and (B22) ratio VR, defined as follows:

EBP=α

(1/DT)+β

RR+γ

VR+δ

, where α

is the first coefficient, β and

γ

are the second coefficients, and δ

is the constant, an intraarterial blood pressure of the subject, based on each of a plurality of values of the time DT successively obtained by the first means, and each of a plurality of values of the period RR, and each of a plurality of values of the ratio VR, successively obtained by the second means when said each value of the time DT is obtained by the first means.

5. An apparatus according to claim 4, further comprising a second memory device which stores at least one group of predetermined first and second coefficients α

, β

, γ

of the expression that are predetermined by applying the multiple regression analysis to a plurality of groups of information which are obtained from a plurality of persons and each group of which comprises a blood pressure obtained from a corresponding one of the persons, and a time DT, a period RR, and a ratio VR which are obtained from said one person when said blood pressure is obtained from said one person, wherein, before the first memory device stores more than said first predetermined number of groups of information, the blood-pressure estimating means successively estimates, according to the expression having said one group of predetermined first and second coefficients α

, β

, γ

, an intraarterial blood pressure of the subject, based on each of a plurality of values of the time DT successively obtained by the first means and each of a plurality of values of the period RR, and each of a plurality of values of the ratio VR, successively obtained by the second means when said each value of the time DT is obtained by the first means.

6. An apparatus according to claim 1, wherein the second means comprises means for obtaining the set of third information selected from the group consisting of the area defined by the volume pulse wave, a ratio of the area to a heart-beat period of the subject, a ratio of the area to a product of the heart-beat period and an amplitude of the volume pulse wave, and a ratio of a product of the area and the amplitude to the heart-beat period.

7. An apparatus according to claim 1, wherein the first means comprises:

a first pulse-wave sensor and a second pulse-wave sensor which non-invasively detect the pulse wave from two different portions of the artery of the subject, respectively; and

means for determining, as the set of first information, a time which is needed for the pulse wave to propagate between the two different portions of the artery.

8. An apparatus according to claim 7, wherein the second means comprises means for determining, as the set of second information, a time difference between respective predetermined points of two successive heartbeat-synchronous pulses of the pulse wave detected by one of the first and second pulse-wave sensors.

9. An apparatus according to claim 7, wherein the second means comprises one of the first and second pulse-wave sensors, said one pulse-wave sensor detecting the volume pulse wave from the peripheral portion of the subject.

10. An apparatus according to claim 7, wherein the first and second pulse-wave sensors comprise an electrocardiograph and a photoelectric oximeter.

11. An apparatus for successively estimating an intraarterial blood pressure of a living subject, based on information non-invasively obtained from a circulatory organ of the subject, comprising:

a blood-pressure measuring device which includes an inflatable cuff adapted to apply a pressing force to a body portion of the subject and iteratively measures, by changing the pressing force of the cuff, a blood pressure of the subject;

a first means for non-invasively obtaining, from the circulatory organ of the subject, a set of first information which relates to a velocity of propagation of a pulse wave which propagates through an artery of the subject, at least each time the blood-pressure measuring device measures a blood pressure of the subject;

a second means for non-invasively obtaining, from the circulatory organ of the subject, at least one of a set of second information which relates to a heart rate of the subject and a set of third information which relates to an area defined by a volume pulse wave from a peripheral portion of the subject, at least each time the blood-pressure measuring device measures said blood pressure;

a memory device which stores a plurality of groups of information each group of which comprises said blood pressure measured by the blood-pressure measuring device, the set of first information obtained by the first means when said blood pressure is measured by the blood-pressure measuring device, and said at least one of the set of second information and the set of third information obtained by the second means when said blood pressure is measured by the blood-pressure measuring device;

an expression determining means for determining an expression representing a relationship between (A) blood pressure, and (B1) first information and (B2) at least one of (B21) second information and (B22) third information, the expression having a first coefficient for the first information, at least one second coefficient for said at least one of the second information and the third information, and a constant, the expression determining means determining the first and second coefficients and the constant of the expression, based on more than a predetermined number of said groups of information last stored in the memory device, the predetermined number being equal to a total number of the first coefficient, said at least one second coefficient, and the constant; and

a blood-pressure estimating means for successively estimating, according to the determined expression representing the relationship between (A) blood pressure, and (B1) first information and (B2) at least one of (B21) second information and (B22) third information, an intraarterial blood pressure of the subject, based on each of a plurality of sets of first information successively obtained by the first means and each of a plurality of sets of said at least one of the second information and the third information successively obtained by the second means when said each set of first information is obtained by the first means.

12. An apparatus according to claim 11, wherein the expression determining means comprises means for determining the first and second coefficients and the constant of the expression, by applying a statistic analysis to more than said predetermined number of groups of information last stored in the memory device.

13. An apparatus according to claim 11, wherein the expression determining means comprises means for determining the first and second coefficients and the constant of the expression, by applying a multiple regression analysis to more than said predetermined number of groups of information last stored in the memory device.