Arterial-wall stiffness evaluation system

• US 9,730,594 B2
• Filed: 09/17/2008
• Issued: 08/15/2017
• Est. Priority Date: 09/17/2008
• Status: Active Grant

• Current Assignee: National Institute of Advanced Industrial Science and Technology (Government of Japan), Shisei Datum Co., Ltd.
• Original Assignee: National Institute of Advanced Industrial Science and Technology (Government of Japan), Shisei Datum Co., Ltd.
• Inventors: Komine, Hidehiko, Asai, Yoshiyuki, Yokoi, Takashi, Saito, Yukiyoshi
• Primary Examiner(s): Mallari, Patricia
• Assistant Examiner(s): CATINA, MICHAEL ANTHONY
• Application Number:
  US13/063,518
• Publication Number:
  US 20110172546A1
• Time in Patent Office: 3,254 Days
• Field of Search: 600481, 600485, 600490, 600494
• CPC Class Codes: A61B 5/02007 Evaluating blood vessel condition, e.g. elasticity, compliance
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/02116 of pulse wave amplitude A61B5/02225 takes precedence
• CPC Class Codes: A61B 5/107 Measuring physical dimensions, e.g. size of the entire body or parts thereof
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives

Abstract

An arterial-wall stiffness evaluation system of the present invention includes: a cuff to be attached to a part of a living body; a pressure sensor for detecting pressure in the cuff; a cuff-pressure control section for controlling the pressure in the cuff to be increased or decreased up to a predetermined value, based on a value detected by the pressure sensor; and a data processing section for calculating, based on pulse waves detected by the pressure sensor, pulse-wave amplitudes of cuff-pressure pulse waves and blood-pressure pulse waves, and for evaluating arterial-wall stiffness based on the pulse-wave amplitudes. The arterial-wall stiffness is evaluated by a pressure-diameter characteristic curve, which represents a relationship between vascular diameter and transmural pressure applied to a vascular wall, or by estimation from shapes and amplitudes of the detected pulse waves. Alternatively, the evaluation is performed by estimating, from the detected pulse waves, a differential function obtainable by differentiating a pressure-diameter characteristic curve with respect to a transmural pressure, or by use of an arctan or a sigmoid function. This allows anybody to easily evaluate blood vessel stiffness anytime with high accuracy even at home without any special knowledge.

Claims

1. An arterial-wall stiffness evaluation system comprising:

a cuff to be attached to a part of a living body;

a pressure sensor for detecting pressure in the cuff, and

a control section including

a cuff-pressure control section for controlling the pressure in the cuff to be increased or decreased to a predetermined value, based on a value detected by the pressure sensor; and

a data processing section for calculating, based on pulse waves detected by the pressure sensor, pulse-wave amplitudes of cuff-pressure pulse waves and blood-pressure pulse waves, and for evaluating arterial-wall stiffness based on the pulse-wave amplitudes thus calculated,

wherein said data processing section performs the following steps of;

i) obtaining respective ratios between amplitudes of extracted cuff-pressure pulse waves and corresponding pulse pressures in respective pulse-wave zones including a transmural pressure of P applied to a vascular wall and determining an average value of the respective ratios as a differential value corresponding to the transmural pressure of P applied to a vascular wall, wherein a pulse-wave zone is a zone on an axis representing the transmural pressure which zone corresponds to an amplitude of a blood-pressure pulse wave at a certain time point;

ii) performing the step i) twice or more so as to obtain a plurality of average values each being the average value obtained in the step i), and obtaining a set of points respectively corresponding to the plurality of average values;

iii) fitting a curve determined by a differentiated arctan function to the set of points;

iv) determining the arterial-wall stiffness according to a parameter of the differentiated arctan function; and

v) outputting said arterial-wall stiffness to a user.