APPARATUS AND METHOD FOR PROCESSING PULSE WAVES

• US 20090018408A1
• Filed: 07/03/2008
• Published: 01/15/2009
• Est. Priority Date: 07/05/2007
• Status: Active Grant

• Current Assignee: TDK Corporation
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: OUCHI, Kazushige, Suzuki, Takuji
• Granted Patent: US 8,167,800 B2
• Time in Patent Office: Days
• US Class Current: 600/301
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/0002 Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network A61B5/07 takes precedence; transmission systems for measured values G08C; transmission H04B; transmission of digital information H04L; wireless communication networks H04W
• CPC Class Codes: A61B 5/02 Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
• CPC Class Codes: A61B 5/681 Wristwatch-type devices
• CPC Class Codes: A61B 5/6816 Ear lobe
• CPC Class Codes: A61B 5/721 using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured

Abstract

Pulse wave signal data expressing the pulse wave of a subject and body movement signal data expressing body movements of the subject are obtained so that a correlation coefficient expressing the degree of correlation between the pulse wave signal data and the body movement signal data is calculated. One or more pieces of the pulse wave signal data in which the correlation coefficient is equal to or larger than a predetermined threshold value are eliminated.

Claims

1. A pulse wave processing apparatus comprising:

an obtaining unit that obtains pulse wave signal data expressing a pulse wave of a subject and body movement signal data expressing body movements of the subject;

a correlation coefficient calculating unit that calculates a correlation coefficient expressing a degree of correlation between the pulse wave signal data and the body movement signal data; and

a pulse wave eliminating unit that eliminates one or more pieces of the pulse wave signal data in which the correlation coefficient is equal to or larger than a predetermined threshold value.

2. The apparatus according to claim 1, further comprising a pulse-wave interval detecting unit that detects first pulse wave interval data for each pulse beat by using a waveform of the pulse wave expressed by the pulse wave signal data, wherein

the pulse wave eliminating unit calculates third pulse wave interval data that is obtained by eliminating second pulse wave interval data from the first pulse wave interval data, the second pulse wave interval data expressing a pulse wave interval in which the correlation coefficient is equal to or larger than a predetermined threshold value.

3. The apparatus according to claim 2, wherein the correlation coefficient calculating unit calculates the correlation coefficient at a time when a pulse wave interval for the each pulse beat is detected.

4. The apparatus according to claim 2, wherein

the correlation coefficient calculating unit determines an applicable range of the pulse wave signal data that is to be used for calculating the correlation coefficient, based on the first pulse wave interval data, and calculates the correlation coefficient by using a piece of the pulse wave signal data within the determined applicable range.

5. The apparatus according to claim 1, wherein

the body movement signal data includes a plurality of pieces of signal data, and

the correlation coefficient calculating unit determines a priority level of at least one of the pieces of signal data, and calculates the correlation coefficient expressing the degree of correlation between at least one of the pieces of signal data having a highest priority level and the pulse wave signal data.

6. The apparatus according to claim 5, wherein

the pulse wave processing apparatus further comprises a posture estimating unit that estimates a posture of the subject based on the body movement signal,

the correlation coefficient calculating unit determines the priority levels of the pieces of signal data according to a descending order of a degree of correlation between each of the pieces of signal data and the estimated posture of the subject, and calculates the correlation coefficient expressing the degree of correlation between at least one of the pieces of signal data having a highest priority level and the pulse wave signal data.

7. The apparatus according to claim 5, wherein

the pulse wave processing apparatus further comprises a movement estimating unit that estimates a movement of the subject based on the body movement signal,

the correlation coefficient calculating unit determines the priority levels of the pieces of signal data according to a descending order of a degree of correlation between each of the pieces of signal data and the estimated movement of the subject, and calculates the correlation coefficient expressing the degree of correlation between at least one of the pieces of signal data having a highest priority level and the pulse wave signal data.

8. The apparatus according to claim 2, further comprising an output unit that outputs at least one of the pulse wave signal data, the body movement signal data, and the third pulse wave interval data.

9. The apparatus according to claim 8, further comprising an output unit that outputs posture data expressing an estimated posture of the subject.

10. The apparatus according to claim 8, further comprising an output unit that outputs movement data expressing an estimated movement of the subject.

11. The apparatus according to claim 1, further comprising a pulse wave measuring unit that measures a pulse wave of the subject and outputs the pulse wave signal data expressing the pulse wave, wherein

the obtaining unit obtains the pulse wave signal data output from the pulse wave measuring unit.

12. The apparatus according to claim 1, further comprising a movement measuring unit that measures a movement of the subject and outputs the movement signal data expressing the movement, wherein

the obtaining unit obtains the movement signal data output from the movement measuring unit.

13. The apparatus according to claim 12, wherein

the body movement measuring unit includes a three-axis acceleration sensor and measures accelerations in three axial directions that are orthogonal to one another, and outputs, as the body movement signal data, a signal that contains data of the accelerations in the three axial directions as signal data.

14. A pulse wave processing method executed by a pulse wave processing apparatus that includes an obtaining unit, a correlation coefficient calculating unit, and a pulse wave eliminating unit, the method comprising:

obtaining pulse wave signal data expressing a pulse wave of a subject and body movement signal data expressing body movement of the subject by employing the obtaining unit;

calculating a correlation coefficient expressing a degree of correlation between the pulse wave signal data and the body movement signal data by employing the correlation coefficient calculating unit; and

eliminating one or more pieces of the pulse wave signal data in which the correlation coefficient is equal to or larger than a predetermined threshold value by employing the pulse wave eliminating unit.