Blood pressure measuring apparatus

• US 6,068,601 A
• Filed: 01/08/1998
• Issued: 05/30/2000
• Est. Priority Date: 09/20/1995
• Status: Expired due to Term

• Current Assignee: Omron Healthcare Company Limited (Omron Corporation)
• Original Assignee: Colin Corporation (Fukuda Denshi Company Limited)
• Inventors: Miyazaki, Makoto, Hayakawa, Tokuji, Harada, Chikao, Miwa, Yoshihisa, Yokozeki, Akihiro
• Primary Examiner(s): Nasser, Robert L.
• Application Number:
  US09/004,382
• Time in Patent Office: 873 Days
• Field of Search: 600/490, 600/493-6, 600/500
• US Class Current: 600/490
• CPC Class Codes: A61B 5/0225 the pressure being controlled by electric signals, e.g. derived from Korotkoff sounds

Abstract

A blood pressure measuring apparatus including an inflatable cuff which is adapted to be wound around a body portion of a living subject, an air pump which supplies a pressurized air to the cuff to inflate the cuff and thereby increase an air pressure in the cuff, so that the cuff presses the body portion of the subject, an air tank which is connected to the air pump, an air restrictor which is provided between the air tank and the cuff, a deflation-control valve which is provided between the restrictor and the cuff to control an amount of discharging of the pressurized air from the cuff and thereby control deflation of the cuff, a control device which controls the air pump to supply the pressurized air to the cuff while controlling the deflation-control valve to discharge a controlled amount of the pressurized air therethrough from the cuff, so as to increase the pressure of the cuff linearly at a predetermined first rate, and a measuring device which measures at least one blood pressure value of the subject based on a pulse wave which is produced from an artery of the body portion of the subject in synchronism with a heartbeat of the subject while the pressure of the cuff is linearly increased at the first rate by the control device.

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;

an air pump which supplies a pressurized air to said cuff to inflate the cuff and thereby increase an air pressure in the cuff, so that the cuff presses the body portion of the subject;

an air tank which is connected to said air pump;

an air restrictor which is provided between said air tank and said cuff;

a deflation-control valve which is provided between said restrictor and said cuff to control an amount of discharging of the pressurized air from the cuff and thereby control deflation of the cuff;

a control device which controls said air pump to supply the pressurized air to said cuff while controlling said deflation-control valve to discharge a controlled amount of the pressurized air therethrough from said cuff, so as to increase the pressure of said cuff linearly at a predetermined first rate; and

a measuring device which measures at least one blood pressure value of the subject based on a pulse wave which is produced from an artery of the body portion of the subject in synchronism with a heartbeat of the subject while the pressure of the cuff is linearly increased at said first rate by said control device.

2. An apparatus according to claim 1, wherein said control device comprises:

cuff-volume estimating means for estimating an initial volume of said cuff at a time when the cuff is initially wound around the body portion of the subject, based on a rate of increase of the pressure of the cuff obtained when said air pump is operated to supply the pressurized air at a predetermined second rate to the cuff; and

control-value determining means for determining a control value corresponding to the estimated initial volume of said cuff, so that said air pump is operated, according to the determined control value, to increase said pressure of the cuff at said first rate.

3. An apparatus according to claim 2, wherein said control-value determining means comprises means for determining, as said control value, an electric energy which is supplied to said air pump to increase said pressure of said cuff at said first rate.

4. An apparatus according to claim 2, wherein said control-value determining means comprises means for determining, as said control value, a changeable control value which increases, as time passes, to increase said pressure of said cuff at said first rate.

5. An apparatus according to claim 2, wherein said volume-estimating means comprises means for estimating said initial volume of said cuff based on a time duration needed to increase the pressure of said cuff from a predetermined first value to a predetermined second value higher than said first value, and wherein said control device further comprises means for controlling said air pump and said deflation-control valve to increase the pressure of said cuff up to said first value.

6. An apparatus according to claim 1, wherein the control device comprises means for increasing, while controlling the deflation-control valve to discharge the controlled amount of the pressurized air from the cuff, an electric energy supplied to the air pump, and thereby increasing a rotation speed of a rotating member of the air pump, so as to increase the pressure of the cuff linearly at the predetermined first rate.

7. An apparatus according to claim 1, wherein the control device comprises means for selectively operating the air pump, the deflation-control valve, and the measuring device in (a) a pressure-increase blood-pressure measuring mode in which the measuring device measures at least one blood pressure value of the subject based on a pulse wave which is produced from the artery of the body portion of the subject in synchronism with the heartbeat of the subject while the pressure of the cuff is linearly increased at the predetermined first rate by the air pump and the deflation-control valve, and (b) a pressure-decrease blood-pressure measuring mode in which the measuring device measures at least one blood pressure value of the subject based on a pulse wave which is produced from the artery of the body portion of the subject in synchronism with the heartbeat of the subject while the pressure of the cuff is decreased by the deflation-control valve after the pressure of the cuff is increased to a predetermined target value by the air pump.

8. A blood pressure measuring apparatus comprising:

an inflatable cuff which is adapted to be wound around a body portion of a living subject;

an air pump which supplies pressurized air to said cuff to inflate the cuff and thereby increase air pressure in the cuff, so that the cuff presses the body portion of the subject;

an air tank which is provided between, and connected to, said air pump and said cuff;

a deflation-control valve which is provided between said air tank and said cuff to control an amount of discharging of the pressurized air from the cuff and thereby control deflation of the cuff;

a control device which controls said air pump to supply the pressurized air to said cuff while controlling said deflation-control valve to discharge a controlled amount of the pressurized air therethrough from said cuff, so as to increase the pressure of said cuff linearly at a predetermined first rate; and

a measuring device which measures at least one blood pressure value of the subject based on a pulse wave which is produced from an artery of the body portion of the subject in synchronism with a heartbeat of the subject while the pressure of the cuff is linearly increased at said first rate under the control of said control device.

9. An apparatus according to claim 8, wherein said control device comprises:

cuff-volume estimating means for estimating an initial volume of said cuff at a time when the cuff is initially wound around the body portion of the subject, based on a rate of increase of the pressure of the cuff obtained when said air pump is operated to supply the pressurized air at a predetermined second rate to the cuff; and

control-value determining means for determining a control value corresponding to the estimated initial volume of said cuff, so that said air pump is operated, according to the determined control value, to increase said pressure of the cuff at said first rate.

10. An apparatus according to claim 9, wherein said control-value determining means comprises means for determining, as said control value, an electric energy which is supplied to said air pump to increase said pressure of said cuff at said first rate.

11. An apparatus according to claim 9, wherein said control-value determining means comprises means for determining, as said control value, a changeable control value which increases, as time passes, to increase said pressure of said cuff at said first rate.

12. An apparatus according to claim 9, wherein said volume-estimating means comprises means for estimating said initial volume of said cuff based on a time duration needed to increase the pressure of said cuff from a predetermined first value to a predetermined second value higher than said first value, and wherein said control device further comprises means for controlling said air pump and said deflation-control valve to increase the pressure of said cuff up to said first value.

13. An apparatus according to claim 8, wherein said measuring device comprises:

a pressure sensor which detects the pressure of said cuff and produces an electric signal representing the detected cuff pressure, the detected cuff pressure comprising first pulsations corresponding to said pulse wave and second pulsations resulting from the operation of the air pump; and

a band-pass filter which extracts, from said electric signal, said first pulsations corresponding to said pulse wave.

14. An apparatus according to claim 8, wherein the control device comprises means for increasing, while controlling the deflation-control valve to discharge the controlled amount of the pressurized air from the cuff, an electric energy supplied to the air pump, and thereby increasing a rotation speed of a rotating member of the air pump, so as to increase the pressure of the cuff linearly at the predetermined first rate.

15. An apparatus according to claim 8, wherein the control device comprises means for selectively operating the air pump, the deflation-control valve, and the measuring device in (a) a pressure-increase blood-pressure measuring mode in which the measuring device measures at least one blood pressure valve of the subject based on a pulse wave which is produced from the artery of the body portion of the subject in synchronism with the heartbeat of the subject while the pressure of the cuff is linearly increased at the predetermined first rate by the air pump and the deflation-control valve, and (b) a pressure-decrease blood-pressure measuring mode in which the measuring device measures at least one blood pressure value of the subject based on a pulse wave which is produced from the artery of the body portion of the subject in synchronism with the heartbeat of the subject while the pressure of the cuff is decreased by the deflation-control valve after the pressure of the cuff is increased to a predetermined target value by the air pump.