Electronic blood pressure meter having improved cuff repressurization means

• US 4,872,461 A
• Filed: 05/31/1988
• Issued: 10/10/1989
• Est. Priority Date: 10/15/1987
• Status: Expired due to Fees

• Current Assignee: Isao Kai, Omron Tateisi Electronics Co. (Omron Corporation)
• Original Assignee: Isao Kai, Omron Tateisi Electronics Co. (Omron Corporation)
• Inventors: Miyawaki, Yoshinori
• Primary Examiner(s): JAWORSKI, FRANCIS J
• Application Number:
  US07/200,551
• Time in Patent Office: 497 Days
• Field of Search: 128/680-683, 364/413.03
• US Class Current: 600/494
• CPC Class Codes: A61B 5/02116 of pulse wave amplitude A61B5/02225 takes precedence
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
• 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

Abstract

In an electronic blood pressure meter, pressurization requirement of the cuff is minimized by predicting a systolic blood pressure level from blood vessel information which may be obtained with an initial cuff pressure which is lower than the systolic blood pressure. The prediction of the systolic blood pressure may be based on a diastolic blood pressure, a maximum pulse wave amplitude value, on other pulse wave amplitude value, a cuff pressure value corresponding to the other pulse wave amplitude value and an empirically obtained parameter. Thus, since the cuff pressure is not increased any more than required, the discomfort to the subject person and the time period required for blood pressure measurement are both minimized and the accuracy of blood pressure measurement is improved.

Claims

1. An electronic blood pressure meter, comprising:

a cuff which can be pressurized into applying pressure to a part of a human patient;

pressurization means for pressurizing the cuff, wherein said pressurization means initially pressurizes the cuff to an initial cuff pressure which may or may not be above the systolic pressure of said patient;

depressurization means for depressurizing the cuff;

pressure sensing means for detecting a pressure of the cuff while said depressurization means is depressurizing said cuff and for providing an output thereof;

blood vessel information detecting means for detecting blood vessel information of the part of the human patient and for providing an output thereof;

detecting means for detecting, based on said blood vessel information, whether the initial cuff pressure was below the systolic pressure of the patient;

predicting mean, responsive to detection of a sub-systolic initial cuff pressure, for computing a predicted systolic pressure value from the outputs of the pressure sensing means and from the blood vessel information detecting means;

repressurization level determining means for determining a repressurization level based on the predicted systolic pressure value computed by said predicting means if said detecting means detects a sub-systolic initial cuff pressure;

repressurization means for instructing said pressurization means to pressurize said cuff to said repressurization level if said detecting means detects a sub-systolic initial cuff pressure; and

blood pressure value determining means for determining systolic and diastolic pressure values according to said outputs from the blood vessel information detecting means and the pressure sensing means.

2. The electronic blood pressure meter as claimed in claim 1, wherein the blood vessel information comprises pulse wave data obtained from the pressure sensor, further comprising means for determining a maximum pulse wave amplitude, means for determining one other pulse wave amplitude, means for determining a cuff pressure value corresponding to said one other pulse wave amplitude, and means for obtaining an empirically determined parameter, and wherein said predicted systolic pressure is predicted using said diastolic pressure value, said maximum pulse wave amplitude, said one other pulse wave amplitude, said cuff pressure value which corresponds to said one other pulse wave amplitude, and said empirically determined parameter.

3. The electronic blood pressure meter as claimed in claim 2, wherein said predicted systolic pressure value is determined according to the following relationships:

space="preserve" listing-type="equation">P.sub.s* =(P.sub.1 -P.sub.d)/V+P.sub.d ;

space="preserve" listing-type="equation">U=(A.sub.1 /A.sub.m)×

100; and

space="preserve" listing-type="equation">V=V(U);

wherein

P_s* is the predicted systolic pressure value;

P_d is the diastolic pressure value;

A_m is the maximum pulse wave amplitude;

A₁ is the one other pulse wave amplitude;

P₁ is the cuff pressure value which corresponds to the one other pulse wave amplitude; and

V(U) is an empirically determined mathematical function from which is empirically determined parameter is obtained.

4. The electronic blood pressure meter as claimed in claim 3, comprising a CPU having a memory which defines a lookup table, wherein said mathematical function V(U) is stored in said lookup table.

5. The electronic blood pressure meter as claimed in claim 3, wherein said mathematical function V(U) is given by a linear approximation.

6. A method for measuring blood pressure, comprising:

attaching a cuff which can be pressurized to a part of a human patient;

pressurizing the cuff, wherein said cuff is initially pressurized to an initial cuff pressure which may or may not be above the systolic pressure of said patient;

depressurizing the cuff;

detecting a pressure of the cuff while said cuff is depressurized and providing an output corresponding thereto;

detecting blood vessel information of the part of the human patient and providing an output corresponding thereto;

detecting, based on said blood vessel information, whether the initial cuff pressure was below the systolic pressure of the patient;

computing, upon detection of a sub-systolic initial cuff pressure, a predicted systolic pressure value from the outputs of the pressure sensing step and from the blood vessel information detecting step;

determining a repressurization level based on the predicted systolic pressure value computed in said predicting step if a sub-systolic initial cuff pressure is detected;

pressurizing said cuff to said repressurization level if a sub-systolic initial cuff pressure is detected; and

determining systolic and diastolic pressure values according to said outputs from the blood vessel information detecting step and the pressure sensing step.

7. The method as claimed in claim 6, wherein the blood vessel information comprises pulse wave data obtained from the pressure sensor, further comprising determining a maximum pulse wave amplitude, determining one other pulse wave amplitude, determining a cuff pressure value corresponding to said one other pulse wave amplitude, and obtaining an empirically determined parameter, and wherein said predicted systolic pressure is predicted using said diastolic pressure value, said maximum pulse wave amplitude, said one other pulse wave amplitude, said cuff pressure value which corresponds to said one other pulse wave amplitude, and said empirically determined parameter.

8. The method as claimed in claim 7, wherein said predicted systolic pressure value is determined according to the following relationships:

space="preserve" listing-type="equation">P.sub.s* =(P.sub.1 -P.sub.d)/V+P.sub.d ;

space="preserve" listing-type="equation">U=(A.sub.1 /A.sub.m)×

100; and

space="preserve" listing-type="equation">V=V(U);

wherein

P_s* is the predicted systolic pressure value;

P_d is the diastolic pressure value;

A_m is the maximum pulse wave amplitude;

A₁ is the one other pulse wave amplitude;

P₁ is the cuff pressure value which corresponds to the one other pulse wave amplitude; and

V(U) is an empirically determined mathematical function from which said empirically determined parameter is obtained.

9. The method as claimed in claim 8, wherein said mathematical function V(U) is stored in a lookup table defined in a memory of a CPU.

10. The method as claimed in claim 8, wherein said mathematical function V(U) is given by a linear approximation.

11. An electronic blood pressure meter, comprising:

a cuff which can be pressurized into applying pressure to a part of a human patient;

pressurization means for pressurizing the cuff, wherein said pressurization means initially pressurizes the cuff to an initial cuff pressure;

depressurization means for depressurizing the cuff;

pressure sensing means for detecting a pressure of the cuff while said depressurization means is depressurizing said cuff and for providing an output thereof;

pulse wave data detecting means for detecting pulse wave data of the part of the human patient and for providing an output thereof;

means for determining a diastolic pressure value according to said outputs from the pulse wave data detecting means and the pressure sensing means;

means for determining a maximum pulse wave amplitude;

means for determining one another pulse wave amplitude;

means for determining a cuff pressure value corresponding to said one other pulse wave amplitude;

means for obtaining an empirically determined parameter; and

predicting means for computing a predicted systolic pressure value according to the following relationships;

space="preserve" listing-type="equation">P.sub.s* =(P.sub.1 -P.sub.d)/V+P.sub.d ;

space="preserve" listing-type="equation">U=(A.sub.1 /A.sub.m)×

100; and

space="preserve" listing-type="equation">V=V(U);

wherein

P_s* is the predicted systolic pressure value;

P_d is the diastolic pressure value;

A_m is the maximum pulse wave amplitude;

A₁ is the one other pulse wave amplitude;

P₁ is the cuff pressure value which corresponds to the one other pulse wave amplitude; and

V(U) is an empirically determined mathematical function from which said empirically determined parameter is obtained.

12. The electronic blood pressure meter as claimed in claim 11, comprising a CPU having a memory which defines a lookup table, wherein said mathematical function V(U) is stored in said lookup table.

13. The electronic blood pressure meter as claimed in claim 11, wherein said mathematical function V(U) is given by a linear approximation.

14. A method for measuring blood pressure, comprising:

applying a cuff which can be pressurized to a part of a human patient;

pressurizing the cuff, wherein said cuff is initially pressurizing to an initial cuff pressure;

depressurizing the cuff;

detecting a pressure of the cuff while said cuff is depressurized and providing an output corresponding thereto;

detecting pulse wave data of the part of the human patient and providing an output corresponding thereto;

determining a diastolic pressure value according to said outputs from the pulse wave data detecting step and the pressure sensing step;

determining a maximum pulse wave amplitude;

determining one other pulse wave amplitude;

determining a cuff pressure value corresponding to said one other pulse wave amplitude;

obtaining an empirically determined parameter; and

computing a predicted systolic pressure value according to the following relationships;

space="preserve" listing-type="equation">P.sub.s* =(P.sub.1 -P.sub.d)/V+P.sub.d;

space="preserve" listing-type="equation">U=(A.sub.1 /A.sub.m)×

100; and

space="preserve" listing-type="equation">V=V(U);

wherein

P_s* is the predicted systolic pressure value;

P_d is the diastolic pressure value;

A_m is the maximum pulse wave amplitude;

A₁ is the one other pulse wave amplitude;

P₁ is the cuff pressure value which corresponds to the one other pulse wave amplitude; and

V(U) is an empirically determined mathematical function from which said empirically determined parameter is obtained.

15. The method as claimed in claim 14, wherein said mathematical function V(U) is stored in a lookup table defined by a memory by a CPU.

16. The method as claimed in claim 14, wherein said mathematical function V(U) is given by a linear approximation.