Device to measure vascular function

• US 5,582,179 A
• Filed: 05/17/1994
• Issued: 12/10/1996
• Est. Priority Date: 05/17/1993
• Status: Expired due to Term

• Current Assignee: Omron Healthcare Company Limited (Omron Corporation)
• Original Assignee: Omron Corporation
• Inventors: Yanagi, Shinsaku, Shimizu, Masashi, Shirasaki, Osamu, Miyawaki, Yoshinori
• Primary Examiner(s): Sykes, Angela D.
• Application Number:
  US08/245,112
• Time in Patent Office: 938 Days
• Field of Search: 128/668, 128/672, 128/677, 128/680-3, 128/687-90, 128/691, 128/694
• US Class Current: 600/500
• 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

Abstract

A measuring device to measure vascular function of an artery includes a cuff that is attachable to a specified part of a body to constrict the artery, a pulse wave amplitude calculating device that calculates an amplitude of a pulse wave that is synchronous with a heartbeat and is based on a change in a volume of the artery, and an inference device that infers a pressure-to-volume characteristic for the artery based on the amplitude of the pulse wave and a corresponding pressure. A blood pressure meter incorporating the measuring device uses a measure of the vascular function to determine a degree of sclerosis in the artery.

Claims

1. A measuring device to measure vascular function of an artery, comprising:

a cuff that is attachable to a specified part of a body to constrict the artery,

a pulse wave amplitude calculating device that calculates an amplitude of a pulse wave that is synchronous with a heartbeat and is based on a change in a volume of the artery, and

an inference device that infers a vascular function that corresponds to a pressure-to-volume characteristic for the artery based on the amplitude of the pulse wave and e corresponding cuff pressure in said cuff,

wherein said inference device comprises a processor that;

selects a first pulse wave,

selects a second pulse wave having a corresponding cuff pressure that is separated from a cuff pressure corresponding to the first pulse wave by an amount equal to the difference between a systolic and diastolic blood pressure of the body to whom said cuff is attached, and

approximates a function that corresponds to the relationship between the arterial pressure and the internal volume of the artery when the cuff pressure is in the region between the cuff pressures corresponding to the first and second pulse waves.

2. The measuring device of claim 1, wherein the processor uses the approximated function to determine the relationship between the arterial pressure and the internal volume of the artery when the cuff pressure is in a region between the cuff pressure corresponding to the second pulse wave and a cuff pressure corresponding to the second pulse wave plus the difference between a systolic and diastolic blood pressure of the body to whom the cuff is attached.

3. The measuring device of claim 2, wherein the processor interpolates data about the relationship between the arterial pressure and the internal volume of the artery to determine the relationship between the arterial pressure and the internal volume of the artery when the cuff pressure is greater than the cuff pressure corresponding to the second pulse wave plus the difference between the systolic and diastolic blood pressure of the body to whom the cuff is attached.

4. The measuring device of claim 2, wherein the approximated function is an exponential function of pressure.

5. The measuring device of claim 1, wherein the pulse wave amplitude calculating device comprises:

a pulse wave extracting device that detects and extracts a pulse wave component that is synchronous with a heartbeat and is based on a change in a volume of an artery, and

an amplitude calculating device that calculates an amplitude of the pulse wave.

6. The measuring device of claim 1, wherein said pulse wave amplitude calculating device calculates the amplitude of multiple pulse waves as a pressure in said cuff changes.

7. The measuring device of claim 1, further comprising:

a pressure control device to change the cuff pressure within said cuff; and

a cuff pressure detecting device to detect the cuff pressure within said cuff.

8. The measuring device of claim 1, wherein said pulse wave amplitude calculating device calculates the amplitude of multiple pulse waves as the pressure in said cuff decreases.

9. The measuring device of claim 8, wherein the pressure in said cuff decreases in step fashion.

10. The measuring device of claim 9, wherein the pressure in said cuff decreases steadily.

11. The measuring device of claim 1, wherein said pulse wave amplitude calculating device calculates the amplitude of multiple pulse waves as the pressure in said cuff increases.

12. The measuring device of claim 11, wherein the pressure in said cuff increases in step fashion.

13. The measuring device of claim 11, wherein the pressure in said cuff increases steadily.

14. A blood pressure meter comprising:

a cuff that is attachable to a specified part of the body to constrict an artery;

a pulse wave extracting device to detect and extract a pulse wave component that is synchronous with a heartbeat based on a change in a volume of said artery when a cuff pressure in said cuff changes;

an amplitude calculating device to calculate an amplitude of said pulse wave;

a blood pressure calculating device to calculate a systolic blood pressure and diastolic blood pressure based on said cuff pressure and said amplitude of said pulse wave;

an inference device to infer a pressure-to-volume characteristic of said artery based on said amplitude of said pulse wave and said corresponding cuff pressure; and

a judging device to determine a degree of sclerosis in said artery based on said pressure-to-volume characteristic,

wherein said judging device judges the degree of sclerosis in said artery by comparing said pressure-to-volume characteristic to a predetermined pressure-to-volume characteristic, and

further comprising an input device to input an age of the body to whom said cuff is attached, wherein said judging device uses said age to select said predetermined pressure-to-volume characteristic.

15. The blood pressure meter of claim 14, further comprising a display to display said degree of sclerosis determined by said judging device.