Blood pressure monitoring apparatus and method

• US 8,206,309 B2
• Filed: 04/04/2008
• Issued: 06/26/2012
• Est. Priority Date: 04/04/2007
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Oh, Hyun Ho, Shim, Bong Chu, Lee, Youn Jae, Lee, Kwy Ro, Hong, Hyung Ki, Cho, Seong Moon
• Primary Examiner(s): DUNSTON, JENNIFER ANN
• Application Number:
  US12/062,838
• Publication Number:
  US 20080249382A1
• Time in Patent Office: 1,544 Days
• Field of Search: None
• US Class Current: 600/485
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6838 Clamps or clips
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives

Abstract

The blood pressure monitoring apparatus and method are disclosed that can monitor a blood pressure of a subject using an electrocardiogram signal, a pulse wave signal and a body characteristic information of the subject, wherein the electrocardiogram signal and the pulse wave signal of the subject are monitored to remove a noise signal generated from monitoring of the pulse wave signal, allowing monitoring a precise blood pressure of the subject, and calculating the pulse wave analysis information using the monitored pulse wave signal, and using the electrocardiogram signal and the pulse wave signal to calculate a pulse transit time (PPT), and plugging a calculated pulse wave propagation time, pulse wave analysis information and body characteristic information of the subject into a predetermined regression equation to monitor the blood pressure.

Claims

1. A blood pressure monitoring apparatus comprising:

an electrocardiogram monitoring unit configured to monitor an electrocardiogram signal of a subject;

a photoplethysmography (PPG) monitoring unit configured to emit an optical signal of a predetermined frequency to a subject'"'"'s body, detect an optical signal that has reflected from or penetrated the subject'"'"'s body, and deemphasize noise within the detected optical signal to generate a pulse wave signal;

a body characteristic information input unit configured to enable input of body characteristic information of the subject;

a micro computer configured to calculate pulse wave analysis information using the pulse wave signal, to calculate a pulse wave propagation time using the pulse wave signal and the electrocardiogram signal, and to calculate a blood pressure of the subject using the calculated pulse wave analysis information, the pulse wave propagation time, and the body characteristic information inputted by the body characteristic information input unit, wherein the micro computer is configured to calculate the blood pressure by inputting the pulse wave propagation time, the pulse wave analysis information and the body characteristic information into the following regression equation;

2. The apparatus as claimed in claim 1, wherein the electrocardiogram monitoring unit comprises:

electrocardiogram monitoring electrodes configured to monitor an electric signal of the body by being brought into contact with the body; and

an electrocardiogram monitoring circuit configured to generate an electrocardiogram signal using the electric signal monitored by the electrocardiogram monitoring electrodes and output the generated electrocardiogram signal to the micro computer.

3. The apparatus as claimed in claim 1, wherein the PPG monitoring unit comprises:

a PPG sensor configured to generate an optical signal of a predetermined frequency, emit the generated optical signal to the body of the subject, receive an optical signal reflected from the body, and convert the received optical signal to an electric signal; and

a PPG monitoring circuit configured to discern a noise signal and a signal of the predetermined frequency from the electric signal converted by the PPG sensor, generate the pulse wave signal using the discerned signal of the predetermined frequency, and input the generated pulse wave signal to the micro computer.

4. The apparatus as claimed in claim 3, wherein the PPG sensor comprises:

an optical transmitter configured to generate an optical signal of a predetermined frequency and emit the generated optical signal of the predetermined frequency to the body of the subject; and

an optical signal receiver configured to receive the optical signal reflected from the body and convert the received optical signal into an electric signal.

5. The apparatus as claimed in claim 4, further comprising an optical device driving unit configured to drive an optical device of the optical signal transmitter in response to the signal of the predetermined frequency.

6. The apparatus as claimed in claim 3, wherein the PPG monitoring circuit comprises:

a current/voltage converter configured to convert an output current of the PPG sensor into a voltage;

a tuned amplifier configured to tune the voltage converted by the current/voltage converter by a frequency scope that includes a band of a predetermined frequency to remove noise; and

a pulse wave extractor comprising a demodulator and a lowpass filter, the pulse wave extractor configured to mix a signal output by the tuned amplifier with the signal of the predetermined frequency, lowpass filter to extract a pulse wave signal, and output the pulse wave signal to the micro computer.

7. The apparatus as claimed in claim 6, further comprising an analog-to-digital converter configured to convert the pulse wave signal extracted by the pulse wave extractor and output the converted signal to the micro computer.

8. The apparatus as claimed in claim 6, wherein:

the demodulator is configured to multiply the signal output by the tuned amplifier by the signal of the predetermined frequency; and

the lowpass filter is configured to lowpass filter a signal output by the demodulator to extract a pulse wave signal.

9. The apparatus as claimed in claim 6, wherein the pulse wave extractor is integrally disposed in the micro computer.

10. The apparatus as claimed in claim 6, wherein the tuned amplifier and the pulse wave extractor are integrally disposed in the micro computer.

11. The apparatus as claimed in claim 1, wherein the body characteristic information includes at least one of sex, weight, height, length of an arm and age of the subject.

12. The apparatus as claimed in claim 1, wherein the micro computer is further configured to compute a second derivative of the pulse wave signal, and to calculate, as pulse wave analysis information:

a pulse frequency of the subject monitored by the pulse wave signal; and

peak values of an acceleration waveform derived from the second derivative of the pulse wave signal.

13. The apparatus as claimed in claim 1, further comprising storage configured to store the calculated blood pressure under the control of the micro computer.

14. The apparatus as claimed in claim 1, further comprising storage configured to store the body characteristic information of the subject, and to enable retrieval of the body characteristic information of the subject from among body characteristic information stored for other subjects responsive to input at the body characteristic information input unit of information corresponding to the subject.

15. The apparatus as claimed in claim 1, wherein the PPG monitoring unit is configured to deemphasize noise within the detected optical signal by removing noise.

16. The apparatus as claimed in claim 1, wherein the PPG monitoring unit is configured to deemphasize noise within the detected optical signal by emphasizing a component of the detected optical signal other than noise, relative to the noise.

17. A blood pressure monitoring apparatus comprising:

an electrocardiogram monitoring unit configured to monitor an electrocardiogram signal of a subject;

a photoplethysmography (PPG) monitoring unit configured to emit an optical signal of a predetermined frequency to a subject'"'"'s body, detect an optical signal that has reflected from or penetrated the subject'"'"'s body, and deemphasize noise within the detected optical signal to generate a pulse wave signal;

a body characteristic information input unit configured to enable input of body characteristic information of the subject

a temperature sensor configured to monitor a body temperature of a body part from which the pulse wave signal is monitored;

a micro computer configured to calculate pulse wave analysis information using the pulse wave signal, to calculate a pulse wave propagation time using the pulse wave signal and the electrocardiogram signal, and to calculate a blood pressure of the subject using the calculated pulse wave analysis information, the pulse wave propagation time, the body characteristic information inputted by the body characteristic information input unit, and the body temperature, wherein the micro computer is configured to calculate blood pressure by inputting the pulse wave propagation time, the pulse wave analysis information, the body characteristic information and the body temperature in the following regression equation;

blood pressure (P)=k₁ x pulse wave propagation time

18. A blood pressure monitoring method comprising:

inputting body characteristic information of a subject;

monitoring an electrocardiogram signal of the subject;

emitting an optical signal of a predetermined frequency to the subject'"'"'s body;

detecting an optical signal that has reflected from or penetrated the subject'"'"'s body;

deemphasizing noise within the detected optical signal to generate a pulse wave signal;

calculating a pulse wave propagation time and a pulse wave analysis information using the monitored electrocardiogram signal and pulse wave signal; and

monitoring the blood pressure of the subject based on the calculated pulse wave propagation time, the pulse wave analysis information, and the body characteristic information, wherein monitoring the blood pressure includes inputting the pulse wave propagation time, the pulse wave analysis information and the body characteristic information in the following regression equation;

blood pressure (P)=k₁ x pulse wave propagation time

19. The method as claimed in claim 18, wherein generating the pulse wave signal comprises:

generating an optical signal of a predetermined frequency and emitting the signal to the body of the subject;

receiving the optical signal that has penetrated or has been reflected from the body of the subject and converting the signal to an electric signal;

tuning the electric signal to a frequency band including the predetermined frequency to deemphasize the noise signal;

filtering the tuned electric signal to remove high frequency components; and

generating the pulse wave signal based on the tuned and filtered electric signal.

20. The method as claimed in claim 18, wherein calculating the pulse wave analysis information comprises:

calculating a pulse frequency of the subject;

calculating a second derivative of the pulse wave signal; and

calculating peak values of an acceleration waveform derived from the second derivative of the pulse wave signal.

21. The method as claimed in claim 18, wherein inputting the body characteristic information includes inputting at least one of sex, weight, height, length of an arm and age of the subject.

22. A blood pressure monitoring method comprising:

inputting body characteristic information of a subject;

monitoring an electrocardiogram signal of the subject;

emitting an optical signal of a predetermined frequency to the subject'"'"'s body;

detecting an optical signal that has reflected from or penetrated the subject'"'"'s body;

deemphasizing noise within the detected optical signal to generate a pulse wave signal;

monitoring a body temperature of a body part from which the pulse wave signal is monitored;

calculating a pulse wave propagation time and a pulse wave analysis information using the monitored electrocardiogram signal and pulse wave signal; and

monitoring the blood pressure of the subject based on the calculated pulse wave propagation time, the pulse wave analysis information the body characteristic information and the body temperature, wherein monitoring the blood pressure includes inputting the pulse wave propagation time, the pulse wave analysis information, the body characteristic information and the body temperature in the following regression equation;

blood pressure (P)=k₁ x pulse wave propagation time