Blood-pressure measuring device

• US 6,346,083 B1
• Filed: 07/11/2000
• Issued: 02/12/2002
• Est. Priority Date: 09/06/1999
• Status: Expired due to Term

• Current Assignee: Omron Healthcare Company Limited (Omron Corporation)
• Original Assignee: Colin Corporation (Fukuda Denshi Company Limited)
• Inventors: Nunome, Tomohiro, Nishibayashi, Hideo
• Primary Examiner(s): Nasser, Robert L.
• Assistant Examiner(s): CARTER, RYAN CHRISTOPHER
• Application Number:
  US09/613,767
• Time in Patent Office: 581 Days
• Field of Search: 600/481, 600/485, 600/490, 600/493-496, 600/500
• US Class Current: 600/490
• 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

Abstract

A blood-pressure measuring apparatus including a cuff having an inflatable bag, a first pulse-wave sensor which detects a first pulse wave propagated to the bag, a second pulse-wave sensor which detects a second pulse wave propagated to a downstream-side portion of the cuff wound around a body portion of a subject in a direction of flow of blood in an artery of the body portion, an amplitude correcting device for correcting a first group of respective amplitudes of heartbeat-synchronous pulses of the first pulse wave and/or a second group of respective amplitudes of heartbeat-synchronous pulses of the second pulse wave, so that one or more amplitudes of the first group that correspond to one or more pulses of the first pulse wave that are detected while the flow of blood is stopped by the inflated bag is equal to one or more amplitudes of the second group that correspond to one or more pulses of the second pulse wave that are detected while the flow of blood is stopped by the bag, an amplitude-difference determining device for determining, after the correction, a difference between each of the amplitudes of the first group and a corresponding one of the amplitudes of the second group, and a blood-pressure determining device for determining a blood pressure of the subject based on the respective differences between the respective amplitudes of the first group and the corresponding amplitudes of the second group.

Claims

1. A blood-pressure measuring apparatus, comprising:

an inflatable cuff which is adapted to be wound around a body portion of a living subject and which includes a first inflatable bag which is inflatable to press an arterial vessel of the body portion and stop flow of blood in the arterial vessel;

a first pulse-wave detecting device which detects a first pulse wave which is produced from the arterial vessel and is propagated to the first inflatable bag of the cuff wound around the body portion, the first pulse wave including a plurality of heartbeat-synchronous pulses;

a second pulse-wave detecting device which detects a second pulse wave which is produced from the arterial vessel and is propagated to a downstream-side portion of the cuff wound around the body portion as seen in a direction in which the blood flows in the arterial vessel, the second pulse wave including a plurality of heartbeat-synchronous pulses;

amplitude correcting means for correcting at least one of (a) a first group of respective amplitudes of the heartbeat-synchronous pulses of the first pulse wave detected by the first pulse-wave detecting device and (b) a second group of respective amplitudes of the heartbeat-synchronous pulses of the second pulse wave detected by the second pulse-wave detecting device, so that at least one amplitude of the first group that corresponds to at least one heartbeat-synchronous pulse of the first pulse wave that is detected by the first pulse-wave detecting device while the flow of the blood in the arterial vessel is stopped by the first inflatable bag is substantially equal to at least one amplitude of the second group that corresponds to at least one heartbeat-synchronous pulse of the second pulse wave that is detected by the second pulse-wave detecting device while the flow of the blood in the arterial vessel is stopped by the first inflatable bag;

amplitude-difference determining means for determining a difference between each of the amplitudes of the first group and a corresponding one of the amplitudes of the second group after said at least one of the first and second groups is corrected by the amplitude correcting means; and

blood-pressure determining means for determining a blood pressure of the subject based on the difference between said each of the amplitudes of the first group and said corresponding one of the amplitudes of the second group.

2. An apparatus according to claim 1, wherein the second pulse-wave detecting device comprises:

a second inflatable bag which is supported by the inflatable cuff such that the second inflatable bag is located inside a downstream-side portion of the first inflatable bag as seen in the direction in which the blood flows in the arterial vessel, and which has a dimension as measured in said direction that is smaller than a dimension of the first inflatable bag as measured in said direction; and

a pressure sensor which detects the second pulse wave produced from the arterial vessel and propagated to the second inflatable bag, and which produces an electric signal representing the detected second pulse wave including the heartbeat-synchronous pulses having the respective amplitudes.

3. An apparatus according to claim 2, further comprising a preventing member which prevents the first pulse wave from being transmitted from the first inflatable bag to the second inflatable bag.

4. An apparatus according to claim 2, wherein the first pulse-wave detecting device comprises a pressure sensor which detects the first pulse wave produced from the arterial vessel and propagated to the first inflatable bag, and which produces an electric signal representing the detected first pulse wave including the heartbeat-synchronous pulses having the respective amplitudes.

5. An apparatus according to claim 4, wherein the blood-pressure determining means comprises means for determining, as a systolic blood pressure of the subject, a pressure in the first inflatable bag that is detected by the pressure sensor of the first pulse-wave detecting device, at a time when the respective differences between the amplitudes of the first group and the corresponding amplitudes of the second group significantly change as the pressure of the first inflatable bag changes.

6. An apparatus according to claim 1, further comprising a pressure changing device which changes a pressure in the first inflatable bag of the cuff wound around the body portion to press the arterial vessel and stop the flow of the blood in the arterial vessel.

7. An apparatus according to claim 1, further comprising:

first amplitude determining means for determining the respective amplitudes of the heartbeat-synchronous pulses of the first pulse wave that are detected by the first pulse-wave detecting device while the pressure of the first inflatable bag is changed by the pressure changing device, and thereby providing the first group of amplitudes; and

second amplitude determining means for determining the respective amplitudes of the heartbeat-synchronous pulses of the second pulse wave that are detected by the second pulse-wave detecting device while the pressure of the first inflatable bag is changed by the pressure changing device, and thereby providing the second group of amplitudes.

8. An apparatus according to claim 1, wherein the amplitude correcting means comprises:

amplification-factor determining means for determining an amplification factor based on at least one amplitude of the first group that corresponds to said at least one heartbeat-synchronous pulse of the first pulse wave that is detected by the first pulse-wave detecting device while the flow of the blood in the arterial vessel is stopped by the first inflatable bag, and at least one amplitude of the second group that corresponds to said at least one heartbeat-synchronous pulse of the second pulse wave that is detected by the second pulse-wave detecting device while the flow of the blood in the arterial vessel is stopped by the first inflatable bag; and

calculating means for calculating a product of the amplification factor and each of the amplitudes of said at least one of the first and second groups, and thereby correcting said at least one of the first and second groups.

9. An apparatus according to claim 1, wherein the amplification-factor determining means comprises means for determining the amplification factor by dividing an average of a plurality of amplitudes of the first group that corresponds to a plurality of heartbeat-synchronous pulse of the first pulse wave that are detected by the first pulse-wave detecting device while the flow of the blood in the arterial vessel is stopped by the first inflatable bag, by an average of a plurality of amplitudes of the second group that corresponds to a plurality of heartbeat-synchronous pulse of the second pulse wave that are detected by the second pulse-wave detecting device while the flow of the blood in the arterial vessel is stopped by the first inflatable bag, and wherein the calculating means calculates a product of the amplification factor and each of the amplitudes of the second groups, and thereby correcting the second groups, and the amplitude-difference determining means determines a difference between each of the amplitudes of the first group and a corresponding one of the amplitudes of the second group that have been corrected by the amplitude correcting means.

10. An apparatus according to claim 1, further comprising a display device which displays the blood pressure of the subject determined by the blood-pressure determining means.