Pulse wave detecting apparatus

• US 5,238,000 A
• Filed: 08/29/1991
• Issued: 08/24/1993
• Est. Priority Date: 09/10/1990
• Status: Expired due to Term

• Current Assignee: Colin Medical Technology Corporation (Omron Corporation)
• Original Assignee: Colin Electronics Co., Ltd.
• Inventors: Niwa, Minoru
• Primary Examiner(s): Cohen, Lee S.
• Assistant Examiner(s): Jastrzab, Jeffrey R.
• Application Number:
  US07/752,016
• Time in Patent Office: 726 Days
• Field of Search: 128/672, 128/680, 128/687-690
• US Class Current: 600/502
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
• CPC Class Codes: A61B 5/02255 the pressure being controlled by plethysmographic signals, e.g. derived from optical sensors

Abstract

An apparatus for detecting a pressure pulse wave produced from an artery of a living subject, including a first press member having a first press surface, a pressure sensing device supported by the first press surface, a second press member having a second press surface surrounding the first press surface, a pressing device pressing the first and second press members toward a body surface of the subject so that the first press surface is pressed against the artery via the body surface, the pressure sensing device generating an electric signal representing the pressure pulse wave produced from the artery and transmitted thereto via the body surface, the first and second press members being displaceable relative to each other in a direction in which the first and second press members are pressed by the pressing device, an actuating device displacing the first press member relative to the second press member so that the first press surface is advanced outward from the second press surface, and a determining device determining an optimum amount of the outward advance of the first press surface from the second press surface, by utilizing the electric signal generated from the pressure sensing device when the first press member is displaced outward from the second press member by the actuating device with the second press member being pressed on the body surface by the pressing device.

Claims

1. An apparatus for detecting a pressure pulse wave produced from an arterial vessel of a living subject, comprising:

a housing;

fastening means connected to said housing, for fastening said housing on a body portion of said subject, said fastening means comprising at least one band which is adapted to be wound around said body portion;

a press member including a first press portion having a first press surface, and a second press portion having a second press surface surrounding said first press surface;

pressure sensing means supported by said first press surface;

pressing means disposed between said housing and said press member, for pressing said press member toward a body surface of said subject so that said first press surface is pressed against said arterial vessel of said subject via said body surface;

said pressure sensing means generating an electric signal representing said pressure pulse wave produced from said arterial vessel and transmitted thereto via said body surface;

said first and second press portions being displaceable relative to each other in a direction in which said press member is pressed by said pressing means;

actuating means for displacing said first press portion relative to said second press portion so that said first press surface is advanced outward from said second press surface; and

determining means for determining an optimum amount of the outward advance of said first press surface from said second press surface, by utilizing the electric signal generated by said pressure sensing means when said first press portion is displaced outward from said second press portion by said actuating means with said press member being pressed on said body surface by said pressing means,

said pressing means pressing said press member on said body surface with a predetermined constant pressing force during said outward advance of said first press surface from said second press surface for the determination of said optimum outward advance amount of said first press surface.

2. The apparatus according to claim 1, further comprising:

adjusting means for determining a pulse rate of said subject by utilizing the electric signal generated from said pressure sensing means and adjusting, by utilizing said pulse rate, a rate of said outward advance of said first press surface for the determination of said optimum outward advance amount.

3. The apparatus according to claim 2, wherein said adjusting means determines as said pulse rate a time duration, t, of a pulse of said pressure pulse wave represented by said electric signal from said pressure sensing means, and adjusts said outward advance rate to a value, a/t (a;

constant).

4. The apparatus according to claim 2, wherein said adjusting means determines as said pulse rate a time duration, t, of each of pulses of said pressure pulse wave detected through said pressure sensing means during said outward advance of said first press surface for the determination of said optimum advance amount, and adjusts said outward advance rate to a value, a/t (a;

constant), for detecting the pulse following said each pulse.

5. The apparatus according to claim 1, wherein said determining means (a) collects the electric signal corresponding to a plurality of pulses of said pressure pulse wave while said first press surface is advanced outward from said second press surface;

(b) determines a lower peak magnitude and an amplitude of each of said pulses;

(c) determines a first range of said outward advance amount of said first press surface in which range a change of said amplitude with respect to said outward advance amount is within a first predetermined value and which range contains an advance amount at which said pressure sensing means has detected a pulse having a maximum amplitude of the amplitudes of said pulses, and a second range of said outward advance amount in which range a change of said lower peak magnitude with respect to said outward advance amount is within a second predetermined value; and

(d) determines said optimum outward advance amount based on said first and second ranges.

6. The apparatus according to claim 5, wherein said determining means determines as said optimum outward advance amount (a) an outward advance amount corresponding to the middle point of said second range in the case where said first range contains said second range in entirety thereof;

(b), in the case where said first and second ranges partially overlap each other, an outward advance amount corresponding to the middle point of the overlapping portions of said first and second ranges; and

(c) an outward advance amount corresponding to the middle point of said first range in the case where said second range contains said first range in entirety thereof or in the case where said first and second ranges are separate from each other.

7. The apparatus according to claim 1, wherein said determining means (a) collects the electric signal corresponding to a plurality of pulses of said pressure pulse wave while said first press surface is advanced outward from said second press surface;

(b) determines an amplitude of each of said pulses; and

(c) determines as said optimum outward advance amount an outward advance amount at which said pressure sensing means has detected a pulse having a maximum amplitude of the amplitudes of said pulses.

8. The apparatus according to claim 1, wherein said actuating means ceases advancing said first press surface upon determination of said optimum outward advance amount.

9. The apparatus according to claim 1, wherein said pressure sensing means comprises a plurality of pressure sensing elements each of which detects said pressure pulse wave and generates an electric signal representing the detected pressure pulse wave, said determining means determining an amplitude of each of pulses of the pressure pulse wave detected through said each pressure sensing element, selecting as an optimum pressure sensing element one of said pressure sensing elements which has detected a pulse having a maximum amplitude of the amplitudes determined for said elements, and determining said optimum advance amount by utilizing the electric signal supplied from said optimum pressure sensing element.

10. The apparatus according to claim 1, further comprising blood pressure determining means for identifying an upper and a lower peak of each of pulses of said pressure pulse wave represented by said electric signal from said pressure sensing means, and determining a systolic and a diastolic blood pressure of said subject based on the identified upper and lower peaks, respectively, for said each pulse.

11. The apparatus according to claim 10, further comprising displaying means for indicating a waveform of said pressure pulse wave detected by said pressure sensing means, and the systolic and diastolic blood pressure values determined by said blood pressure determining means.

12. The apparatus according to claim 1, wherein said actuating means comprising:

means for defining a fluid chamber; and

means for supplying said fluid chamber with a pressurized, non-compressible fluid for displacing said first press portion relative to said second press portion.

13. The apparatus according to claim 1, wherein said pressing means comprises:

a support member having an inner space; and

an elastic diaphragm secured to an inner surface of said support member, such that said elastic diaphragm cooperates with said support member to define a fluid chamber in said inner space of said support member.

said first and second press members being supported by one of opposite surfaces of said elastic diaphragm which one surface is remote from the other surface of said diaphragm defining said fluid chamber.

14. The apparatus according to claim 13, further comprising air supply means for supplying said fluid chamber with a pressurized air.

15. The apparatus according to claim 13, further comprising drive means for displacing said support member relative to said housing in a direction intersecting a direction in which said arterial vessel of said subject extends.

16. An apparatus for detecting a pressure pulse wave produced from an arterial vessel of a living subject, comprising:

a first press member having a first press surface;

pressure sensing means supported by said first press surface;

a second press member having a second press surface surrounding said first press surface;

pressing means for pressing said first and second press members toward a body surface of said subject so that said first press surface is pressed against said arterial vessel of said subject via said body surface;

said pressure sensing means generating an electric signal representing said pressure pulse wave produced from said arterial vessel and transmitted thereto via said body surface;

said first and second press member being displaceable relative to each other in a direction in which the first and second press members are pressed by said pressing means;

actuating means for displacing said first press member relative to said second press member so that said first press surface is advanced outward from said second press surface;

determining means for determining an optimum amount of the outward advance of said first press surface from said second press surface, by utilizing the electric signal generated from said pressure sensing means when said first press member is displaced outward from said second press member by said actuating means with the second press member being pressed on said body surface by said pressing means; and

adjusting means for determining a pulse rate of said subject by utilizing the electric signal generated from said pressure sensing means and adjusting, by utilizing said pulse rate, a rate of said outward advance of said first press surface for the determination of said optimum outward advance amount.

17. The apparatus according to claim 16, wherein said adjusting means determines as said pulse rate a time duration, t, of a pulse of said pressure pulse wave represented by said electric signal from said pressure sensing means, and adjusts said outward advance rate to a value, a/t (a;

constant).

18. The apparatus according to claim 16, wherein said adjusting means determines as said pulse rate a time duration, t, of each of pulse of said pressure pulse wave detected through said pressure sensing means during said outward advance of said first press surface for the determination of said optimum advance amount, and adjusts said outward advance rate to a value, a/t (a;

constant), for detecting the pulse following said each pulse.

19. An apparatus for detecting a pressure pulse wave produced from an arterial vessel of a living subject, comprising:

a first press member having a first press surface;

pressure sensing means supported by said first press surface;

a second press member having a second press surface surrounding said first press surface;

pressing means for pressing said first and second press members toward a body surface of said subject so that said first press surface is pressed against said arterial vessel of said subject via said body surface;

said pressure sensing means generating an electric signal representing said pressure pulse wave produced from said arterial vessel and transmitted thereto via said body surface;

said first and second press member being displaceable relative to each other in a direction in which the first and second press members are pressed by said pressing means;

actuating means for displacing said first press member relative to said second press member so that said first pressure surface is advanced outward from said second press surface; and

determining means for determining an optimum amount of the outward advance of said first press surface from said second press surface, by utilizing the electric signal generated from said pressure sensing means when said first press member is displaced outward from said second press member by said actuating means with the second press member being pressed on said body surface by said pressing means, wherein said determining means (a) collects the electric signal corresponding to a plurality of pulses of said pressure pulse wave while said first press surface is advanced outward from said second press surface;

(b) determines a lower peak magnitude and an amplitude of each of said pulses;

(c) determines a first range of said outward advance amount of said first press surface in which range a change of amplitude with respect to said outward advance amount is within a first predetermined value and which range contains an advance amount at which said pressure sensing means has detected a pulse having a maximum amplitude of the amplitudes of said pulses, and a second range of said outward advance amount of in which range a change of said lower peak magnitude with respect to said outward advance amount is within a second predetermined value; and

(d) determines said optimum outward advance amount based on said first and second ranges.

20. The apparatus according to claim 19, wherein said determining means determines as said optimum outward advance amount (a) an outward advance amount corresponding to the middle point of said second range in the case where said first range contains said second range in entirety thereof;

(b), in the case where said first and second ranges partially overlap each other, an outward advance amount corresponding to the middle point of the overlapping portions of said first and second range; and

(c) an outward advance amount corresponding to the middle point of said first range in the case where said second range contains said first range in entirety thereof or in the case where said first and second ranges are separate from each other.