PULSE WAVE MEASURING APPARATUS AND METHOD FOR MEASURING A PULSE WAVE

• US 20090247886A1
• Filed: 03/23/2009
• Published: 10/01/2009
• Est. Priority Date: 03/25/2008
• Status: Active Grant

• Current Assignee: TDK Corporation
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Suzuki, Takuji, Ouchi, Kazushige, Kameyama, Kenichi
• Granted Patent: US 8,257,270 B2
• Time in Patent Office: Days
• US Class Current: 600/500
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/02438 with portable devices, e.g. worn by the patient
• CPC Class Codes: A61B 5/681 Wristwatch-type devices

Abstract

A pulse wave measuring apparatus includes a pulse wave measuring unit measuring pulse wave; a first detection unit detecting first maximum and minimum values; a second detection unit detecting second maximum and minimum values; an update unit updating the first maximum and minimum values with the second maximum and minimum values after time periods; an initialization unit initializing the second maximum and minimum values after updating the first maximum and minimum values; a timing detection unit detecting a time determined by the first maximum and minimum values; and an interval calculation unit calculating a pulse wave interval using the timing.

Claims

1. A pulse wave measuring apparatus comprising:

a pulse wave measuring unit configured to measure pulse wave data;

a first detection unit configured to detect first maximum values and first minimum values from the pulse wave data, and store the first maximum values and the first minimum values in a first value storage unit, respectively;

a second detection unit configured to detect second maximum values, each of which is the next largest value to the first maximum values, and second minimum values, each of which is the next smallest to the first minimum value, from the pulse wave data sequentially, and to store the second maximum values and the second minimum values in a second value storage unit;

an update unit configured to update the first maximum value stored in the first value storage unit with the second maximum value after elapse of a maximum value update time period after updating the last first maximum value, and to update the first minimum value stored in the first value storage unit with the second minimum value after elapse of a minimum value update time period after updating the last first minimum value;

an initialization unit configured to initialize the second value storage unit so that a new second maximum value can be stored in a next cycle of the pulse wave data, in which the last second maximum value is detected, after updating the last first maximum value, and to initialize the second value storage unit so that a new second minimum value can be stored in a next cycle of the pulse wave data, in which the last second minimum value is detected, after updating the last first minimum value;

a timing detection unit configured to detect a timing, at which the pulse wave data intersects a threshold value determined by the last first maximum value and the last first minimum value in two continuous cycles; and

an interval calculation unit configured to calculate a pulse wave interval using the last timing and the present timing detected by the timing detection unit.

2. The apparatus of claim 1, wherein the first detection unit detects a present value of the pulse wave data as the new first maximum value when the present value is larger than the last first maximum value, and

the first detection unit detects the present value as the new first minimum value when the present value is smaller than the last first minimum value.

3. The apparatus of claim 1, wherein the second detection unit detects a present value of the pulse wave data as a new second maximum value when the present value is smaller than the last first maximum value and larger than the last second maximum value;

and

the second detection unit detects the present value as a new second minimum value when the present value is larger than the last first minimum value and smaller than the last second minimum value.

4. The apparatus of claim 1, wherein the second detection unit starts detecting the new second maximum value after the elapse of a maximum value detection start time period after updating the last first maximum value;

and

the second detection unit starts detecting the new second minimum value after a minimum value detection start time period after updating the last first minimum value.

5. The apparatus of claim 1, wherein the initialization unit initializes the last second maximum value after the elapse of a maximum value initialization time period after updating the last second maximum value;

and

the initialization unit initializes the last second minimum value after the elapse of a minimum value initialization time period after updating the last second minimum value.

6. The apparatus of claim 1, further comprising:

a communication unit configured to transmit the pulse wave interval to an external terminal.

7. A method for measuring a pulse wave, comprising:

detecting first maximum values and first minimum values from data of the pulse wave, respectively and sequentially, and storing the first maximum values and the first minimum values in a first value storage unit;

detecting second maximum value, each of which is the next largest to the first maximum values, and second minimum values, each of which is the next smallest to the first minimum values, from the pulse wave data, and storing the second maximum values and the second minimum values to a first value storage unit, respectively;

updating the first maximum value stored in the first value storage unit with the second maximum value after a maximum value update time period has elapsed after updating the last first maximum value;

updating the first minimum value stored in the first value storage unit with the second minimum value after a minimum value update time period has elapsed after updating the last first minimum value;

initializing the second value storage unit so that a new second maximum value can be stored in the next cycle of the pulse wave data, in which the last second maximum value is detected, after updating the last first maximum value;

initializing the second value storage unit so that a new second minimum value can be stored in the next cycle of the pulse wave data, in which the last second minimum value is detected, after updating the last first minimum value;

detecting timing, at which the pulse wave data intersects a threshold value determined by using the last first maximum value and the last first minimum value in two continuous cycles; and

calculating a pulse wave interval using the last timing and the present timing.

8. The method of claim 7, wherein detecting the first maximum values and the first minimum values comprises:

detecting a present value of the pulse wave data as a new first maximum value when the present value is larger than the last first maximum value; and

detecting the present value as a new first minimum value when the present value is smaller than the last first minimum value.

9. The method of claim 7, wherein detecting the second maximum value and the second minimum value comprises:

detecting the present value as a new second maximum value when the present value is smaller than the last first maximum value and larger than the last second maximum value; and

detecting the present value as a new second minimum value sequentially when the present value is larger than the last first minimum value and smaller than the last second minimum value.

10. The method of claim 7, wherein detecting the second maximum value and the second minimum value respectively comprises:

starting detection of the new second maximum value after a maximum value detection start time period has elapsed after updating the last first maximum value; and

starting detecting the new second minimum value after a minimum value detection start time period has elapsed after updating the last first minimum value.

11. The method of claim 7, wherein

initializing the second value storage unit after updating the present first maximum value comprises:

initializing the last second maximum value after a maximum value initialization time period has elapsed after updating the last second maximum value; and

initializing the second value storage unit after updating the present first maximum value comprises;

initializing the last second minimum value after a minimum value initialization time period has elapsed after updating the last second minimum value.

12. The method of claim 7, further comprising:

transmitting the pulse wave interval to an external terminal.