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EP-4013299-B1 - BLOOD PRESSURE MEASUREMENT SYSTEMS AND METHODS

EP4013299B1EP 4013299 B1EP4013299 B1EP 4013299B1EP-4013299-B1

Inventors

  • SHIH, WEN-PIN
  • CHIEN, WEI-TING
  • CHEN, LENG-CHUN

Dates

Publication Date
20260513
Application Date
20200814

Claims (14)

  1. A system for blood pressure measurement of an individual, the system comprising: a controller (3) coupled to a pressing unit (1) and to a bioinformation measurement device (2); wherein the controller (3) is configured to incrementally increase a pressure applied by the pressing unit (1) on a body part of an individual during a first pressing period (P1) and a second pressing period (P2) to compress the body part such that the pressing unit (1) exerts the pressure on an upstream blood vessel relative to a downstream blood vessel measured by the bioinformation measurement device (2); wherein the bioinformation measurement device (2) is configured to produce a first wave signal (W1) that is representative of blood pressure activity from the downstream blood vessel during the first pressing period (P1) and transmitting the first wave signal (W1) to the controller (3); wherein the controller (3) generates an envelope signal (E1) using the first wave signal (W1); wherein the controller (3) is configured to produce a second wave signal (W2) that is representative of blood pressure activity from the downstream blood vessel during the second pressing period (P2) and transmitting the second wave signal (W2) to the controller (3), wherein the second pressing period (P2) begins when the bioinformation measurement device (2) fails to detect the blood pressure activity from the downstream blood vessel; wherein the controller (3) determines a first timepoint (T1a) by determining where a waveform of the second wave signal (W2) intersects with a waveform of the envelope signal (E1), wherein the controller (3) determines a systolic pressure value (Sa) by determining a first pressure value that the pressing unit (1) exerts on the upstream blood vessel at the first timepoint (T1a); and wherein the controller (3) determines a second timepoint (T2a) by determining where the envelope signal (E1) has a predetermined amplitude (A2), wherein the controller (3) determines a diastolic pressure value (Da) by determining a second pressure value that the pressing unit (1) exerts on the upstream blood vessel at the second timepoint (T2a).
  2. The system of claim 1, wherein the first wave signal (W1) has a plurality of periodic waves (C1, C2, ..., Cn), and wherein the controller generates the envelope signal (E2) using the first wave signal (W1) comprises: calculating an average value of each periodic wave of the first wave signal (W1) (S302); obtaining a first modified wave signal (W1') by subtracting the average value from the predetermined amplitude of each corresponding periodic wave (C1, C2, ..., Cn) (S304); and obtaining the envelope signal (E2) by connecting a plurality of peaks of the first modified wave signal (W1') and a plurality of valleys of the first modified wave signal (W1') (S306).
  3. The system of claim 1, wherein the first wave signal (W1) has a plurality of periodic waves (C1, C2, ..., Cn), wherein the controller (3) generates the envelope signal (E1) by connecting peaks of each periodic wave (C1, C2, ..., Cn) and valleys of each periodic wave (C1, C2, ..., Cn) (S306).
  4. The system of claim 1 where the controller (3) is further configured to: detect a third wave signal (W3) from the upstream blood vessel by using the bioinformation measurement device (2) during a non-pressing period of the pressing unit (1), where the third wave signal (W3) comprises a continuous wave; output the systolic pressure value (Sa) as an initial peak value of a peak in the third wave signal (W3); output the diastolic pressure value (Da) as an initial valley value of a valley in the third wave signal (W3) that is temporally adjacent to the peak in the third wave signal (W3); and calculate a plurality of additional peak values and a plurality of additional valley value of a plurality of remaining peaks and valleys, respectively, in the third wave signal (W3) according to the systolic pressure value (Sa) and the diastolic pressure value (Da) (S406).
  5. The system of claim 1, wherein the controller (3) is configured to determine the first timepoint (T1b) by: obtaining an average line (W2') of the second wave signal (W2); obtaining a modified envelope signal (E1') by smoothing the envelope signal (E1); and determine the first timepoint (T1b) as a time when an upper bound of the modified envelope signal (E1') intersects with the average line (W2').
  6. The system of claim 1, wherein the predetermined amplitude (A2) of the envelope signal (E1) is between 50% and 90% of a maximum amplitude (A1) of the envelope signal (E1).
  7. The system of claim 1, wherein the pressing unit (1) is configured to fit on an arm or a wrist, wherein the controller (3) is configured to cause the pressing unit (1) to apply pressure during the first pressing period (P1) and the second pressing period (P2), and wherein the bioinformation measurement device (2) is configured to detect the first wave signal (W1) and the second wave signal (W2) from a finger.
  8. A blood pressure measurement method comprising: detecting a first pressure wave signal (W1) from a blood vessel by using a bioinformation measurement device (2) during a first pressing period (P1) of a wearable pressing unit (1), in which the wearable pressing unit (1) exerts pressure on an upstream blood vessel relative to the blood vessel; generating an envelope signal (E1) of the first pressure wave signal (W1) according to the first pressure wave signal (W1); detecting a second pressure wave signal (W2) of the blood vessel by using the bioinformation measurement device (2) during a second pressing period (P2) of the wearable pressing unit (1); determining a first timepoint (T1a) where a waveform of the second pressure wave signal (W2) intersects with a waveform of the envelope signal (E1); outputting a pressure value that the wearable pressing unit (1) exerts on the upstream blood vessel at the first timepoint (T1a) as a systolic pressure value (Sa); determining a second timepoint (T2a) where the envelope signal (E1) has a predetermined amplitude (A2); and outputting the pressure value that the wearable pressing unit (1) exerts on the upstream blood vessel at the second timepoint (T2a) as a diastolic pressure value (Da).
  9. The method of claim 8, wherein the first pressure wave signal (W1) has a plurality of periodic waves (C1, C2, ..., Cn) and generating the envelope signal (E2) further comprises: calculating an average value of each periodic wave (C1, C2, ..., Cn) of the first pressure wave signal (W1); obtaining a first modified wave signal (W1') by subtracting the average value from an amplitude of each corresponding periodic wave (C1, C2, ..., Cn); and obtaining the envelope signal (E2) by connecting all the peaks and then all the valleys of the first modified wave signal (W1').
  10. The method of claim 8, wherein the first pressure wave signal (W1) has a plurality of periodic waves (C1, C2, ..., Cn) and generating the envelope signal (E1) further comprises obtaining the envelope signal (E1) by connecting peaks of each periodic wave (C1, C2, ..., Cn) and valleys of each periodic wave (C1, C2, ..., Cn).
  11. The method of claim 8, further comprising: detecting a third wave signal (W3) from the blood vessel by using the bioinformation measurement device (2) during a non-pressing period of the wearable pressing unit (1), where the third wave signal (W3) is a continuous wave; outputting the systolic pressure value (Sa) as a peak value of a peak in the third wave signal (W3); outputting the diastolic pressure value (Da) as a valley value of the valley that is temporally adjacent to the peak in the third wave signal (W3); and calculating peak and valley values of the remaining peaks and valleys, respectively, in the third wave signal (W3) according to the systolic pressure value (Sa) and the diastolic pressure value (Da).
  12. The method of claim 8, wherein determining the first timepoint (T1b) further comprises: obtaining an average line (W2') of the second wave signal (W2); obtaining a modified envelope signal (E1') by smoothing the envelope signal (E1); and determining the first timepoint (T1b) as a time when an upper bound of the modified envelope signal (E1') intersects with the average line (W2').
  13. The method of claim 8, wherein the predetermined amplitude (A2) of the envelope signal (E1) is between 50% and 90% of a maximum amplitude (A1) of the envelope signal (E1).
  14. The method of claim 8, wherein the wearable pressing unit (1) applies pressure on an arm or a wrist during the first (P1) and the second pressing period (P2), and wherein the bioinformation measurement device (2) detects the first pressure wave signal (W1) and the second pressure wave signal (W2) from a finger.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This patent application claims the benefit of U.S. provisional applications No. 62/886,368 filed on August 14, 2019. FIELD This patent specification is in the field of a blood pressure measurement method and device, and more specifically relates to a method and a device for reducing errors in measuring blood pressure. BACKGROUND OF THE INVENTION Cardiovascular disease (CVD) accounts for approximately a significant number of deaths on a world-wide basis. CVD includes coronary heart disease, which accounts for the majority of CVD deaths, as well as stroke and heart failure. CVD is closely related to pathogenic factors and lifestyles. In addition to maintaining a healthy lifestyle, frequent monitoring of blood pressure, glucose, and cholesterol also plays an important role in preventing CVD. To satisfy the demand of preventing or control CVD, there have been many portable bioinformation monitoring devices available for users to measure their own heart rate, blood pressure, glucose, and etc. In this context, the US-publication US 2019/059825 A1 discloses an indirect oscillometric, digital blood pressure monitoring system enabling self-calibration to obtain absolute blood pressure values. Other systems for blood pressure measurement are known from US 2019/008399 A1 and US 2010/249614 A1. TECHNICAL PROBLEMS Arterial blood pressure is most commonly measured via a sphygmomanometer. Conventionally, when monitoring blood pressure of a patient, during each heartbeat the blood pressure varies between systolic and diastolic pressures. Systolic pressure is a peak pressure in the artery that occurs near the end of the cardiac cycle or contraction. Diastolic pressure is minimum pressure in the artery that occurs near the beginning of the cardiac cycle during filling of the heart with blood. In conventional portable bioinformation monitoring devices that measure blood pressure, a mean blood pressure is usually measured first, and then a systolic and a diastolic pressure are deduced based on statistical relation between systolic, diastolic, and the measured mean blood pressure. However, the relation between systolic, diastolic, and mean blood pressure might be different due to any number of variations in the particular patient. For example, such variations include age, personal physiology, or life environment. Therefore, conventional bioinformation monitoring devices are prone to inevitable measurement errors. In some variations, portable bioinformation monitoring devices combine a conventional blood pressure cuff with a finger-clip sensor. These devices measure systolic pressure by using the method like the conventional way of applying compressive pressure to the artery to cease flow and then removing the pressure. However, this method still produces measurement errors resulting from motion artifact and respiratory variation of the person being tested. Therefore, there remains a need to produce an improved blood pressure measurement reading that reduces errors and increases increasing an accuracy of measuring actual blood pressure. SUMMARY OF INVENTION In view of this, the systems and methods described herein include blood pressure measurement systems that produce an accurate blood pressure measurement. One variation of the system is to directly measure blood pressure with a portable device configuration and also effectively reduce errors subjected to motion artifact and blood pressure fluctuations caused by respiration. In a first example, the system allows for blood pressure measurement of an individual and comprises a controller coupled to a pressing unit and to a bioinformation measurement device; where the controller is configured to incrementally increase a pressure applied by the pressing unit on a body part of an individual during a first pressing period to compress the body part to affect blood flow in an upstream blood vessel in the body part; where the bioinformation measurement device is configured to produce a first wave signal representative of blood activity from a downstream blood vessel during the first pressing period and transmitting the first wave signal to the controller; where the controller generates an envelope signal using the first wave signal; wherein the controller is configured to establish a second pressing period by determining when the bioinformation measurement device fails to detect the blood activity; where the bioinformation measurement device is configured to produce a second wave signal of the blood vessel by using the bioinformation measurement device during the second pressing period; where the controller determines a first timepoint where a waveform of the second wave signal intersects with a waveform of the envelope signal to establish a systolic pressure value using a first pressure value that the pressing unit exerts on the upstream blood vessel at the first timepoint; and where the controller also determines a second timepoint where the env