Sphygmomanometer

• US 4,821,734 A
• Filed: 07/16/1987
• Issued: 04/18/1989
• Est. Priority Date: 04/21/1987
• Status: Expired due to Term

• Current Assignee: Nihon Seimitsu Sokki Company Limited
• Original Assignee: Nihon Seimitsu Sokki Company Limited
• Inventors: Koshino, Shinji
• Primary Examiner(s): Jaworski, Francis
• Application Number:
  US07/074,204
• Time in Patent Office: 642 Days
• Field of Search: 128/680-683, 128/687
• US Class Current: 600/493
• CPC Class Codes: A61B 5/02255 the pressure being controlled by plethysmographic signals, e.g. derived from optical sensors

Abstract

A non-invasive manometer comprises a bladder to be attached to an appendage such as a finger, a leg, a tail or the like in order to apply a pressure thereto. A pressure changing device changes the pressure. Two pairs of photoelectric sensors sense a change in the diameter of the blood vessel due to the applied pressure and the internal pressure of the blood vessel. Each sensor includes a light emitting unit and a photosensitive unit. At least one of the units includes a plurality of elements. The photoelectric sensors are shielded from possible external light and operated alternately in a time-divisional manner. One sensor is disposed closer to the heart than the other sensor. The output of the other sensor is used to determine the highest blood pressure while the outputs of both the sensors are compared to determine the lowest blood pressure.

Claims

1. A non-invasive manometer comprising:

pressure means attached to an appendage for applying a pressure thereto;

pressure changing means for changing the pressure applied to said appendage;

optical means for sensing a change in a blood vessel of the appendage due to the applied pressure of the pressure means and internal pressure of the blood vessel caused by beating of a heart, the optical means including a light emitting unit and a photosensitive unit, the units including at least first and second pairs of light emitting elements and photosensitive elements;

shielding means for shielding the optical means from light external to the optical means;

clock means for operating the light emitting and photosensitive units alternately in a time-divisional manner;

said first pair of light emitting element and photosensitive element being disposed on said appendage closer to said heart than said second pair of light emitting element and photosensitive element, said second pair of light emitting element and photosensitive element, which is disposed on a peripheral side, for determining a systolic blood pressure; and

comparison means for comprising outputs from two or more pairs of elements of the optical means, which are disposed closer to said heart and disposed on the peripheral side, to determine a diastolic pressure when said outputs coincide.

2. A non-invasive manometer comprising:

pressure means attached to an appendage for applying a pressure thereto;

pressure changing means for changing the pressure applied to said appendage;

optical means for sensing a change in a blood vessel of the appendage due to the applied pressure from the pressure means and internal pressure of the blood vessel caused by beatings of a heart, the optical means including a light emitting unit and a photosensitive unit, the units including at least first and second pairs of light emitting elements and photosensitive elements;

shielding means for shielding the optical means from light external to the optical means;

clock means for operating the light emitting and photosensitive units alternately in a time-divisional manner;

phase means for providing a phase in which all emissions of light, from said light emitting unit, stop;

storage means for storing the signal received during the phase when all light emissions stop;

subtraction means for subtracting the stored signal from a signal obtain during light emission;

said first pair of light emitting element and photosensitive element being disposed on said appendage closer to said heart than said second pair of light emitting element and photosensitive element, said second pair of light emitting element and photosensitive element, which is disposed on a peripheral side, for determining a systolic blood pressure; and

comparison means for comparing outputs from two or more pairs of elements of the optical means, which are disposed closer to the heart and disposed on the peripheral side, to determine a diastolic pressure when said outputs coincide.

3. A non-invasive manometer comprising:

pressure means for attachment to an appendage for applying a pressure thereto;

pressure changing means for changing the pressure applied to said appendage;

optical means for sensing a change in a blood vessel of the appendage due to the applied pressure from the pressure means and internal pressure of the blood vessel caused by beating of a heart, the optical means including a light emitting unit and a photosensitive unit, the unit including at least first and second pairs of light emitting elements and photosensitive elements;

said first pair of light emitting element and photosensitive element being disposed on the appendage closer to the heart than said second pair of light emitting element and photosensitive element, said second pair of light emitting element and photosensitive element, which are disposed on a peripheral side, for determining a systolic blood pressure;

comparison means for comparing outputs from two or more pairs of elements of the optical means, which are disposed closer to said heart and disposed on the peripheral side, to determine a diastolic pressure when said outputs coincide;

a variable gain amplifier for applying one or more signals from the elements of the optical means;

stopping means for stopping application of a pressure at a value lower than an average diastolic blood pressure at a beginning of pressurization and depressurization process; and

means for maintaining the pressure value substantially constant while controlling gain of the variable-gain amplifier so that the outputs from the two or more elements of the optical means are equalized in order to measure the diastolic blood pressure.

4. A non-invasive manometer comprising:

pressure means for attachment to an appendage for applying a pressure thereto;

pressure changing means for changing the pressure applied to said appendage;

optical means for sensing a change in a blood vessel of the appendage due to the applied pressure and internal pressure of the blood vessel, the optical means including a light emitting unit and a photosensitive unit;

clock means for operating the optical means in a time-divisional manner;

phase means for providing a phase in which the light emitting unit stops emission;

storage means for storing output from the photosensitive unit during a phase when the light emitting unit does not emit light; and

means for obtaining a difference between an output signal from the photosensitive unit and a stored signal to eliminate influence of light which is external to the optical means.