Pulse-wave propagation time basis blood pressure monitor

• US 5,649,543 A
• Filed: 06/06/1995
• Issued: 07/22/1997
• Est. Priority Date: 06/06/1994
• Status: Expired due to Fees

• Current Assignee: Nihon Kohden Corporation
• Original Assignee: Nihon Kohden Corporation
• Inventors: Sugo, Yoshihiro, Hosaka, Hidehiro, Sakata, Hiroshi, Sohma, Takeshi, Kasuya, Hiromitsu
• Primary Examiner(s): Nasser, Robert L.
• Application Number:
  US08/466,746
• Time in Patent Office: 777 Days
• Field of Search: 128/687, 128/672, 128/677, 128/680-683
• US Class Current: 600/493
• CPC Class Codes: A61B 5/02255 the pressure being controlled by plethysmographic signals, e.g. derived from optical sensors
• CPC Class Codes: A61B 5/0285 Measuring or recording phase velocity of blood waves

Abstract

A pulse-wave propagation time basis blood pressure monitor includes a memory for storing an equation describing the relationship between the pulse wave propagation time and the parameter α, input means for entering the blood pressure value for calibration, a time-interval detect reference point detecting means for detecting a reference point for detecting the time interval of a pulse wave in the aorta of a subject; pulse wave detecting means for detecting a pulse wave which appears in the peripheral blood vessel after it appears in the aorta; pulse-wave propagation time measuring section for measuring a pulse wave propagation time from the output signals of the time-interval detect reference point detecting means and the pulse wave detecting means, first computing means for determining the parameter α proper to the subject on the basis of the general equation stored in the memory by using the pulse wave propagation time for calibration gathered from the subject, second computing means for determining the parameter β to be added in computing a blood pressure value by using the pulse wave propagation time, by using the blood pressure value inputted for calibration, the pulse wave propagation time measured for calibration, and the parameter α determined by the first computing means, third computing means for computing a blood pressure value by using the measured pulse wave propagation time, and the parameters α and β, and measured data output means for outputting data of the computed blood pressure value.

Claims

1. A pulse-wave propagation time basis blood pressure monitor comprising:

a memory for storing information representing a relationship between pulse wave propagation times and values of a parameter α

, each of said pulse wave propagation times being derived from data gathered from a number of subjects;

input means for inputting a blood pressure value of a subject, for calibration;

time-interval detect reference point detecting means for detecting a time of occurrence of a pulse wave in the aorta of a subject;

pulse wave detecting means for detecting a pulse wave which appears in a peripheral blood vessel after said pulse wave appears in the aorta;

pulse-wave propagation time measuring means for measuring pulse wave propagation time from signals output from said time-interval detect reference point detecting means and said pulse wave detecting means, wherein a first measured pulse wave propagation time is used for calibration;

first computing means for determining the parameter α

which corresponds to said pulse wave propagation time used for calibration based upon the information stored in said memory;

second computing means for determining a parameter β

by using said blood pressure value input for calibration, said pulse wave propagation time measured for calibration, and said parameter α

determined by said first computing means;

third computing means for computing a blood pressure value in accordance with another pulse wave propagation time measured by said pulse-wave propagation time measuring means, and the parameters α and

β

; and

measured data output means for outputting at least one of said blood pressure value and said parameter α

.

2. The pulse-wave propagation time basis blood pressure monitor according to claim 1, wherein said information includes one of a predetermined equation and a table describing the relationship between said pulse wave propagation times and said values of said parameter α

stored in said memory.

3. A pulse-wave propagation time basis blood pressure monitor comprising:

a memory for storing information representing a relationship between pulse pressure values and values of a parameter α

, said pulse pressure values being derived from data gathered from a number of subjects;

input means for inputting a blood pressure value of a subject, for calibration;

pulse pressure computing means for computing a pulse pressure for calibration using said blood pressure value received from said input means;

time-interval detect reference point detecting means for detecting a time of occurrence of a pulse wave in the aorta of the subject;

pulse wave detecting means for detecting a pulse wave which appears in a peripheral blood vessel after said pulse wave appears in the aorta;

pulse-wave propagation time measuring means for measuring pulse wave propagation time from output signals of said time-interval detect reference point detecting means and said pulse wave detecting means, wherein a first measured pulse wave propagation time is used for calibration;

first computing means for determining the parameter α

which corresponds to said pulse pressure for calibration computed for the subject based upon the information stored in said memory;

second computing means for determining a parameter β

by using said blood pressure value input for calibration, said pulse wave propagation time used for calibration, and the parameter α

determined by said first computing means;

third computing means for computing a blood pressure value by using another pulse wave propagation time measured by said pulse-wave propagation measuring means, and the parameters α and

β

; and

measured data output means for outputting at least one of said blood pressure value and said parameter α

.

4. The pulse-wave propagation time basis blood pressure monitor according to claim 3, wherein said information includes one of a predetermined equation and a table describing the relationship between said blood pressure values and said values of said parameter α

stored in said memory.

5. A pulse-wave propagation time basis blood pressure monitor comprising:

first input means for inputting at least a patient'"'"'s height value as patient information;

second input means for inputting a blood pressure value for calibration;

time-interval detect reference point detecting means for detecting a time of occurrence of a pulse wave in the aorta of the patient;

pulse wave detecting means for detecting a pulse wave which appears in a peripheral blood vessel after said pulse wave appears in the aorta;

pulse-wave propagation time measuring means for measuring pulse wave propagation time, at a supine position and at one of a sitting and standing position, from output signals of said time-interval detect reference point detecting means and said pulse wave detecting means, wherein a first measured pulse wave propagation time in one of said supine position, said sitting position and said standing position is used for calibration;

first computing means for computing a change Δ

T of said pulse wave propagation time at a time of postural change by using a pulse wave propagation time for calibration measured at said supine position and a pulse wave propagation time for calibration measured at said one of a sitting position and a standing position;

second computing means for computing a change Δ

P of a hydrostatic pressure between the heart and a pulse wave measuring position at the time of postural change, by using the patient'"'"'s height as patient information;

third computing means for determining a parameter α

by using said change Δ

T of said pulse wave propagation time and said change Δ

P of the hydrostatic pressure;

fourth computing means for determining a parameter β

by using said blood pressure value input for calibration, said pulse wave propagation time used for calibration, and the parameter α

determined by said third computing means;

fifth computing means for computing a blood pressure value by using another pulse wave propagation time measured by said pulse-wave propagation time measuring means, and the parameters α and

β

; and

measured data output means for outputting at least one of said blood pressure value, said parameter α and

said parameter β

.

6. A method for measuring blood pressure using a pulse-wave propagation time basis blood pressure monitor comprising the steps of:

storing information describing the relationship between pulse wave propagation times and values of a parameter α

in a memory, each of said pulse wave propagation times being derived from data gathered from a number of subjects;

inputting a blood pressure value of a subject for calibration;

detecting a reference point for detecting a time of occurrence of a pulse wave in the aorta of the subject;

detecting a pulse wave which appears in a peripheral blood vessel after said pulse wave appears in the aorta;

measuring a pulse wave propagation time from said reference point and said pulse wave which appears in the peripheral blood vessel for calibration;

determining the parameter α

proper to the subject based upon the information stored in said memory corresponding to said pulse wave propagation time for calibration gathered from the subject;

determining a parameter β

by using said blood pressure value input for calibration, said pulse wave propagation time for calibration, and the parameter α

;

measuring a second propagation time of another pulse wave into the peripheral blood vessel;

computing a blood pressure value in accordance with said second pulse wave propagation time, and the parameters α and

β

; and

outputting at least one of said blood pressure value, said parameter α and

said parameter β

.

7. A method for measuring blood pressure using a pulse-wave propagation time basis blood pressure monitor, comprising the steps of:

storing information describing the relationship between pulse pressure values and values of a parameter α

in a memory, said pulse pressure values being derived from data gathered from a number of subjects;

inputting a blood pressure value of the subject for calibration;

computing a pulse pressure for calibration using said blood pressure value;

detecting a reference point for detecting a time of occurrence of a pulse wave in the aorta of the subject;

detecting a pulse wave which appears in a peripheral blood vessel after said pulse wave appears in the aorta;

measuring a pulse wave propagation time from said time of occurrence of said pulse wave in the aorta of the subject and said pulse wave of said peripheral blood vessel;

determining the parameter α

proper to the subject based upon the information stored in said memory corresponding to said pulse pressure for calibration gathered from the subject;

determining a parameter β

by using said blood pressure value input for calibration, said pulse wave propagation time and the parameter α

;

measuring a second propagation time of another pulse wave into the peripheral blood vessel;

computing a blood pressure value by using said second pulse wave propagation time, and the parameters α and

β

; and

outputting at least one of said blood pressure value, said parameter α and

said parameter β

.