Augmentation-index measuring apparatus

• US 6,659,958 B2
• Filed: 01/28/2003
• Issued: 12/09/2003
• Est. Priority Date: 04/17/2002
• Status: Expired due to Term

• Current Assignee: Fukuda Denshi Company Limited
• Original Assignee: Colin Corporation (Fukuda Denshi Company Limited)
• Inventors: Narimatsu, Kiyoyuki, Tampo, Akira
• Primary Examiner(s): Nasser, Robert L.
• Application Number:
  US10/352,230
• Publication Number:
  US 20030199775A1
• Time in Patent Office: 315 Days
• Field of Search: 600/485, 600/490, 600/493-6, 600/500-503
• US Class Current: 600/485
• CPC Class Codes: A61B 5/02007 Evaluating blood vessel condition, e.g. elasticity, compliance
• 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 5/7239 using differentiation including higher order derivatives

Abstract

An augmentation-index measuring apparatus including a cuff which is adapted to be worn on a portion of a living subject to press the portion, a fourth-order-differentiating device for subjecting a cuff pulse wave obtained from the cuff, to a fourth-order differentiation, and thereby obtaining a fourth-order-differentiated waveform, a peak-point determining device for determining, based on the fourth-order-differentiated waveform obtained by the fourth-order-differentiating device, a peak point of an incident-wave component contained in the cuff pulse wave and a peak point of a reflected-wave component contained in the cuff pulse wave, and an augmentation-index determining device for determining an augmentation index of the subject that indicates a proportion of one of a first magnitude of the cuff pulse wave at a time of occurrence of the peak point of the incident-wave component and a second magnitude of the cuff pulse wave at a time of occurrence of the peak point of the reflected-wave component, to the other of the first and second magnitudes.

Claims

1. An augmentation-index measuring apparatus comprising:

a cuff which is adapted to be worn on a portion of a living subject to press said portion;

a fourth-order-differentiating device which subjects a cuff pulse wave obtained from the cuff, to a fourth-order differentiation, and thereby obtaining a fourth-order-differentiated waveform;

a peak-point determining device which determines, based on the fourth-order-differentiated waveform obtained by the fourth-order-differentiating device, a peak point of an incident-wave component contained in the cuff pulse wave and a peak point of a reflected-wave component contained in the cuff pulse wave; and

an augmentation-index determining device which determines an augmentation index of the subject that indicates a proportion of one of a first magnitude of the cuff pulse wave at a time of occurrence of the peak point of the incident-wave component and a second magnitude of the cuff pulse wave at a time of occurrence of the peak point of the reflected-wave component, to the other of the first and second magnitudes.

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

a reference-point determining device which determines, as a reference point, a rising point of the cuff pulse wave; and

a window determining device which determines a rising-point window based on the rising point determined by the reference-point determining device,

wherein the peak-point determining device determines the peak point of the incident-wave component, based on a zero-crossing point of the fourth-order-differentiated waveform that falls in the rising-point window determined by the window determining device.

3. An apparatus according to claim 2, wherein the peak-point determining device selects, as the peak point of the incident-wave component, one of a plurality of zero-crossing points of the fourth-order-differentiated waveform that fall in the rising-point window, such that the selected one zero-crossing has a predetermined relationship with respect to a starting point or an ending point of the rising-point window.

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

a reference-point determining device which determines, as a reference point, a notch point of the cuff pulse wave; and

a window determining device which determines a notch-point window based on the notch point determined by the reference-point determining device,

wherein the peak-point determining device determines the peak point of the reflected-wave component, based on a zero-crossing point of the fourth-order-differentiated waveform that falls in the notch-point window determined by the window determining device.

5. An apparatus according to claim 4, wherein the peak-point determining device selects, as the peak point of the incident-wave component, one of a plurality of zero-crossing points of the fourth-order-differentiated waveform that falls in the notch-point window, such that the selected one zero-crossing has a predetermined relationship with respect to a starting point or an ending point of the notch-point window.

6. An apparatus according to claim 1, further comprising a cuff-pressure changing device which changes, for a blood-pressure measurement, a pressure in the cuff from a pressure higher than a systolic blood pressure of said portion of the subject to a pressure lower than a diastolic blood pressure of said portion of the subject, wherein the cuff pulse wave is obtained, before or after the blood-pressure measurement, from the cuff having a pressure lower than the diastolic blood pressure of the subject obtained from the blood-pressure measurement.

8. A method of inspecting arteriosclerosis of a subject comprising:

Measuring an augmentation index with the measuring apparatus of claim 1; and

inspecting arteriosclerosis of the subject based on the augmentation index.

7. An augmentation-index measuring apparatus comprising:

a cuff which is adapted to be worn on a portion of a living subject to press said portion;

a fourth-order-differentiating means for subjecting a cuff pulse wave obtained from the cuff, to a fourth-order differentiation, and thereby obtaining a fourth-order-differentiated waveform;

a peak-point determining means for determining, based on the fourth-order-differentiated waveform obtained by the fourth-order-differentiating device, a peak point of an incident-wave component contained in the cuff pulse wave and a peak point of a reflected-wave component contained in the cuff pulse wave; and

an augmentation-index determining means for determining an augmentation index of the subject that indicates a proportion of one of a first magnitude of the cuff pulse wave at a time of occurrence of the peak point of the incident-wave component and a second magnitude of the cuff pulse wave at a time of occurrence of the peak point of the reflected-wave component, to the other of the first and second magnitudes.