Blood pressure measurement device and calibration method thereof

1. A blood pressure measurement device, comprising:

a blood pressure measurement body configured to determine blood pressure based on photoplethysmogram (PPG); and

a calibrator configured to measure blood pressure values based on Korotkoff sounds,

wherein the calibrator is further configured to provide initial calibration parameters to the blood pressure measurement body, and

the blood pressure measurement body is further configured to collect an electrocardiogram (ECG) signal and a PPG signal, update a PPG parameter-blood pressure equation according to the initial calibration parameters to obtain an updated PPG parameter-blood pressure equation, and calculate a blood pressure value according to the updated PPG parameter-blood pressure equation;

wherein the updated PPG parameter-blood pressure equation comprises:

SBP= a ·( x−x 0 )+SBP 0 ; and

DBP

=

b

·

DBP

0

·

y

0

y

+

c

;

wherein SBP stands for systolic pressure; SBP 0 is an initial systolic pressure; x 0 =PTT 0 or x 0 = PTT 0 ; PTT 0 and PTT 0 are an initial PPG transmission time and an average initial PPG transmission time, respectively; x=PTT, or x= PTT , PTT and PTT are a PPG transmission time and an average PPG transmission time, respectively; and a is a statistic constant, and

DBP stands for diastolic pressure; DBP 0 is an initial diastolic pressure; y 0 =PIR 0 or y 0 = PIR 0 ; PIR 0 and PIR 0 are an initial PPG peak-to-valley ratio and an average initial PPG peak-to-valley ratio, respectively; y=PIR or y= PIR , PIR and PIR are a PPG peak-to-ratio and an average PPG peak-to-ratio, respectively; and b and c are statistic constants.

2. The blood pressure measurement device according to claim 1 , wherein:

the blood pressure measurement body further includes an ECG acquisition device, a PPG acquisition device, a storage device, a first processor, and a first communication device;

the ECG acquisition device is coupled to the first processor, and configured to collect and transmit the ECG signal to the first processor;

the PPG acquisition device is coupled to the first processor, and configured to collect and transmit the PPG signal to the first processor;

the storage device is coupled to the first processor, and configured to store a PPG parameter and the updated PPG parameter-blood pressure equation; and

the first processor is configured to process the ECG signal and the PPG signal, extract and calculate the PPG parameter in a cardiac cycle when receiving a systolic pressure notification signal and when receiving a diastolic pressure notification signal, transmit the PPG parameter of the cardiac cycle, and calculate the blood pressure value according to the updated PPG parameter-blood pressure equation.

3. The blood pressure measurement device according to claim 2 , wherein:

the calibrator includes a cuff, a sound transducer, a pressure gage, a second processor, and a second communication device,

the sound transducer is configured to detect and convert a blood flow sound to an electric signal,

the pressure gage is configured to measure a pressure inside the cuff,

the second processor is configured to process the electric signal, and extract the Korotkoff sounds appeared in a blood flow sound and the pressure inside the cuff at instances that the Korotkoff sounds correspond to the systolic pressure and the diastolic pressure, and

the second communication device is coupled to the second processor, and configured to send a systolic pressure notification signal and a diastolic pressure notification signal, the systolic pressure and the diastolic pressure to the blood pressure measurement body, respectively, at moments that the Korotkoff sounds correspond to the systolic pressure and the diastolic pressure.

4. The blood pressure measurement device according to claim 3 , wherein:

the second communication device includes a receiving device that matches with the first communication device.

5. The blood pressure measurement device according to claim 4 , wherein:

communications between the first communication device and the second communication device include a wired communication or a wireless communication.

6. The blood pressure measurement device according to claim 1 , wherein:

the blood pressure measurement body is further configured to perform calibration based on blood pressure values based on Korotkoff sounds.

7. The blood pressure measurement device according to claim 1 , wherein:

the PTT 0 is derived based on a first initial ECG signal and a second initial PPG signal in a same cardiac cycle during which the SBP 0 is measured; and

the PIR 0 is derived based on a third initial ECG signal and a fourth initial PPG signal in a same cardiac cycle during which the DBP 0 is measured.

8. A calibration method of a blood pressure measurement device, comprising:

measuring a photoplethysmogram (PPG) signal and an electrocardiogram (ECG) signal and calculating PPG parameters, by a blood pressure measurement body, wherein the PPG parameters include a PPG transmission time and a PPG peak-to-valley ratio;

inflating a calibrator;

deflating the calibrator, and when a systolic pressure is detected, sending a systolic pressure notification signal and a systolic pressure at a first instance to the blood pressure measurement body;

after receiving, by the blood pressure measurement body, the systolic pressure notification signal, determining a cardiac cycle that the first instance belongs to, and calculating and recording the PPG parameters in a same cardiac cycle as the systolic pressure, wherein the PPG parameters at least include the PPG transmission time;

when a diastolic pressure is detected, sending a diastolic pressure notification signal and a diastolic pressure at a second instance to the blood pressure measurement body;

after receiving, by the blood pressure measurement body, the diastolic pressure notification signal, determining the cardiac cycle that the second instance belongs to, and calculating and recording the PPG parameters in the same cardiac cycle as the diastolic pressure, wherein the PPG parameters at least include the PPG peak-to-valley ratio, and

updating a PPG parameter-blood pressure equation according to the PPG transmission time and the PPG peak-to-valley ratio; and

wherein the systolic pressure is determined as: SBP=a·(x−x 0 )+SBP 0 , and

the diastolic pressure is determined as:

DBP

=

b

·

DBP

0

·

y

0

y

+

c

;

wherein SBP 0 is an initial systolic pressure; x 0 =PTT 0 or x 0 = PTT 0 ; PTT 0 and PTT 0 are an initial PPG transmission time and an average initial PPG transmission time, respectively; x=PTT, or x= PTT , PTT and PTT are a PPG transmission time and an average PPG transmission time, respectively; and a is a statistic constant, and

DBP 0 is an initial diastolic pressure; y 0 =PIR 0 or y 0 = PIR 0 ; PIR 0 and PIR 0 are an initial PPG peak-to-valley ratio and an average initial PPG peak-to-valley ratio, respectively; y=PIR or y= PIR , PIR and PIR are a PPG peak-to-ratio and an average PPG peak-to-ratio, respectively; and b and c are statistic constants.

9. The calibration method according to claim 8 , wherein:

the PTT 0 is derived based on a first initial ECG signal and a second initial PPG signal in a same cardiac cycle during which the SBP 0 is measured; and

the PIR 0 is derived based on a third initial ECG signal and a fourth initial PPG signal in a same cardiac cycle during which the DBP 0 is measured.

10. The calibration method according to claim 8 , wherein:

the PPG transmission time is a PPG transmission time in a single cardiac cycle, or an average value of PPG transmission time in a plurality of cardiac cycles, and

the PPG peak-to-valley ratio is a PPG peak-to-valley ratio in a single cardiac cycle, or an average value of PPG peak-to-valley ratios in a plurality of cardiac cycles.

11. The calibration method according to claim 8 , wherein:

a limb of a tested user where the blood pressure measurement body is placed is a wrist, a finger, or an arm, and

another limb of the tested user where the calibrator is placed is an arm.

12. The calibration method according to claim 8 , wherein:

communications between the blood pressure measurement body and the calibrator include a wired communication or a wireless communication.

13. A calibration method of a blood pressure measurement device, comprising:

measuring a photoplethysmogram (PPG) signal and an electrocardiogram (ECG) signal and calculating PPG parameters, by a blood pressure measurement body, wherein the PPG parameters include a PPG transmission time and a PPG peak-to-valley ratio;

when a systolic pressure is detected by a calibrator, receiving a systolic pressure notification signal and a systolic pressure at a first instance;

determining a cardiac cycle that the first instance belongs to, and calculating and recording the PPG parameters in a same cardiac cycle as the systolic pressure, wherein the PPG parameters at least include the PPG transmission time;

when a diastolic pressure is detected by the calibrator, receiving a diastolic pressure notification signal and a diastolic pressure at a second instance;

determining the cardiac cycle that the second instance belongs to, and calculating and recording the PPG parameters in the same cardiac cycle as the diastolic pressure, wherein the PPG parameters include the PPG peak-to-valley ratio, and

updating a PPG parameter-blood pressure equation according to the PPG transmission time and the PPG peak-to-valley ratio; and

wherein the systolic pressure is determined as: SBP=a·(x−x 0 )+SBP 0 , and

the diastolic pressure is determined as:

DBP

=

b

·

DBP

0

·

y

0

y

+

c

;

wherein SBP 0 is an initial systolic pressure; x 0 =PTT 0 or x 0 = PTT 0 ; PTT 0 and PTT 0 are an initial PPG transmission time and an average initial PPG transmission time, respectively; x=PTT, or x= PTT , PTT and PTT are a PPG transmission time and an average PPG transmission time, respectively; and a is a statistic constant, and

DBP 0 is an initial diastolic pressure; y 0 =PIR 0 or y 0 = PIR 0 ; PIR 0 and PIR 0 are an initial PPG peak-to-valley ratio and an average initial PPG peak-to-valley ratio, respectively; y=PIR or y= PIR , PIR and PIR are a PPG peak-to-ratio and an average PPG peak-to-ratio, respectively; and b and c are statistic constants.

14. The calibration method according to claim 13 , wherein:

the PTT 0 is derived based on a first initial ECG signal and a second initial PPG signal in a same cardiac cycle during which the SBP 0 is measured; and

the PIR 0 is derived based on a third initial ECG signal and a fourth initial PPG signal in a same cardiac cycle during which the DBP 0 is measured.

15. The calibration method according to claim 13 , wherein:

the PPG transmission time is a PPG transmission time in a single cardiac cycle, or an average value of PPG transmission time in a plurality of cardiac cycles, and

the PPG peak-to-valley ratio is a PPG peak-to-valley ratio in a single cardiac cycle, or an average value of PPG peak-to-valley ratios in a plurality of cardiac cycles.