KR101223454B1 - Blood pressure measurement system having embedded microphone and blood pressure measurement method using embedded microphone - Google Patents

Abstract

A blood pressure measuring system having a built-in microphone and a blood pressure measuring method using a built-in microphone according to the present invention include: a cuff worn on the upper arm of a subject and connected to a conduit through which air is introduced or discharged; A pump connected to the conduit for injecting air into the cuff; A pressure sensor connected to the conduit to detect a pressure signal inside the cuff; A valve connected to the conduit to exhaust air injected into the cuff; And a microphone connected to the conduit to detect an acoustic signal inside the cuff or the conduit when air is exhausted from the cuff, wherein the microphone is provided spaced apart from the cuff and provided to the cuff. It can detect the minute vibration inside the connected conduit. This ensures accurate detection of Korotkoff sounds while eliminating the noise effects of valve operation during blood pressure measurement.

Description

Blood pressure measuring system with built-in microphone and blood pressure measuring method using built-in microphone {BLOOD PRESSURE MEASUREMENT SYSTEM HAVING EMBEDDED MICROPHONE AND BLOOD PRESSURE MEASUREMENT METHOD USING EMBEDDED MICROPHONE}

The present invention relates to a blood pressure measuring system having a built-in microphone and a blood pressure measuring method using a built-in microphone, and more particularly, to a blood pressure measuring system having a built-in microphone capable of increasing accuracy by removing noise that may occur when measuring blood pressure. And it relates to a blood pressure measurement method using a built-in microphone.

Blood pressure is an important indicator of the extent of cardiovascular disease. Blood pressure is caused by the contraction of the ventricles, which causes some of the blood drawn into the aorta to move through the arteries to the periphery, but large amounts of blood are not transported to the periphery and are temporarily contained within the aorta and arteries, whereby the vasculature expands because of its elasticity. Because the aorta and arteries receive more blood than their volume, there is pressure in these vessels. This pressure is arterial pressure, or blood pressure. Mean Arterial Pressure (MAP) is the mean blood pressure during one cardiac cycle and is obtained using Systolic Blood Pressure (SBP) and Diastolic Blood Pressure (DBP). The maximum pressure in the blood vessels when blood in the ventricles is ejected into the aorta by contraction, and the diastolic blood pressure is the pressure in the blood vessels when the blood, which was temporarily stored in the aorta during contraction, flows out to the peripheral vessels and then expands.

The method of measuring blood pressure can be largely classified into a direct method and an indirect method. Direct method is to measure the pressure in the blood vessel by inserting a catheter (catheter) in the blood vessel is a high risk and expensive is used only in the intensive care unit.

The indirect method is a non-invasive method of measuring blood pressure, including auscultatory measurement, palpatory measurement, flush measurement, oscillometric measurement, doppler ultrasound measurement, volume Volume-Oscillometric measurement, Pulse wave velocity measurement, and the like are considered as a standard for blood pressure measurement, and a stethoscope is measured using a mercury sphygmomanometer. However, in recent years, the medical industry is urging the elimination of mercury use, and in general, the electronic sphygmomanometer is commonly used as a substitute for mercury sphygmomanometers in hospitals and homes. Most electronic blood pressure monitors use an oscillometric method.

In the conventional stethoscope-based method of automatic electronic blood pressure apparatus, a contact microphone is worn on the brachial artery to detect Korotkoff Sound, which affects the measurement signal depending on the position of the microphone and burdens the subject. Can give In addition, due to the characteristics of the contact microphone and the characteristics of the microphone exposed to the outside, sensitivity to dynamic noise and environmental noise generated during measurement may be a problem. That is, there is a problem that the microphone includes noise such as an acoustic signal generated by the movement of the subject or an acoustic signal generated by the subject's speech as well as an acoustic signal due to the pressure change of the cuff.

In addition, the oscillometric blood pressure measurement system measures the systolic and diastolic (or diastolic) blood pressure through statistical values based on the pulsation waveform, and there is a problem in that the accuracy of the blood pressure measurement system varies depending on the manufacturer's algorithm. .

In addition, the conventional oscillometric-based blood pressure measuring system or blood pressure measuring device is difficult to calculate the accurate blood pressure because it does not remove the noise generated in the process of decompression of the cuff pressing the upper arm of the subject.

The present invention provides a blood pressure measuring system using a built-in microphone and a blood pressure measuring method using a built-in microphone that does not operate a valve for depressurizing the cuff in a section or time region in which Korotkoff sound is present.

The present invention provides a blood pressure measurement system having a built-in microphone and a built-in microphone capable of detecting and separating the noise or noise present in the vicinity of the cuff that presses the upper arm of the subject and the Korotkoff sound, and a blood pressure measuring method using the built-in microphone. to provide.

The present invention provides a blood pressure measuring system using a built-in microphone and a blood pressure measuring system having a built-in microphone capable of measuring blood pressure from a subject while allowing accurate blood pressure measurement.

 The present invention provides a blood pressure measuring system having a built-in microphone capable of measuring blood pressure with only a cuff without wearing an additional sensor for measuring a blood pressure, and a blood pressure measuring method using a built-in microphone.

Blood pressure measurement system having a built-in microphone according to an embodiment of the present invention for achieving the above object is worn on the upper arm of the subject, the cuff is connected to the air inlet or outlet conduit; A pump connected to the conduit for injecting air into the cuff; A pressure sensor connected to the conduit to detect a pressure signal inside the cuff; A valve connected to the conduit to exhaust air injected into the cuff; And a microphone connected to the conduit to detect an acoustic signal inside the cuff or the conduit when air is exhausted from the cuff, wherein the microphone is provided spaced apart from the cuff and provided to the cuff. It can detect the minute vibration inside the connected conduit.

The microphone may be embedded in the same unit as the pump, the pressure sensor, and the valve, thereby preventing the accuracy of the microphone from being degraded by noise around the cuff.

The microphone may detect an acoustic signal generated during operation of the valve and a Korotkoff sound generated by the cuff among the acoustic signals inside the conduit.

The microphone may be connected to a portion of the conduit that is spaced apart from the portion where the cuff is connected.

The microphone may use a condenser microphone.

On the other hand, according to another aspect of the present invention, the present invention provides a method for measuring blood pressure using the blood pressure measuring system, the step of pressing the cuff using the pump; Depressurizing the cuff at a constant pressure per unit time using the valve after the pressurization of the cuff is completed; Detecting a pressure signal of the cuff by the pressure sensor while depressurizing the cuff; Detecting an acoustic signal inside the conduit using the microphone while depressurizing the cuff; Calculating an operation prohibition period of the valve by analyzing the cuff pressure signal; Extracting a Korotkoff sound from the sound signal detected by the microphone according to whether the valve operation is prohibited; And calculating a systolic blood pressure and a diastolic blood pressure from the Korotkoff sound.

The step of detecting the pressure signal of the cuff by the pressure sensor during the depressurization of the cuff may detect pulsations generated in the process of depressurizing the cuff constantly by the valve.

The step of detecting the pressure signal of the cuff by the pressure sensor during the depressurization of the cuff may detect the pressure signal plus the pulsation, which appears at regular intervals to the pressure inside the cuff which is constantly decreasing.

As the pulsation is added to the pressure inside the cuff which is constantly decreasing, an inflection point may appear in the waveform of the pressure signal.

Analyzing the cuff pressure signal to calculate the operation prohibition section of the valve includes: a first inflection point at which a tangential slope changes from increasing to decreasing with respect to a waveform of the cuff pressure signal; Inflection point can be found.

The calculating of the operation prohibition section of the valve by analyzing the cuff pressure signal may include the time interval obtained by adding the time between the first inflection point and the second inflection point and the predetermined time added to the time corresponding to the second inflection point. It can be calculated as the valve operation prohibition section.

The step of calculating the operation prohibition section of the valve by analyzing the cuff pressure signal may be defined as a section between the valve operation prohibition sections as a valve operation section.

The extracting of the Korotkoff sound from the sound signal detected by the microphone according to whether the valve operation prohibition section is performed may extract the sound signal in the time domain corresponding to the valve operation prohibition section from the sound signal detected by the microphone. Can be.

The extracting of the Korotkoff sound from the sound signal detected by the microphone according to whether the valve operation prohibition section is performed may be performed by generating a corot sound signal having a relatively large amplitude from among the sound signals in the time domain corresponding to the valve operation prohibition section. Can be defined as a cope sound.

As described above, the blood pressure measuring system having a built-in microphone according to the present invention and the blood pressure measuring method using the built-in microphone do not operate the valve to depressurize the cuff in the section or time region where the Korotkoff sound is present. Noise or noise generated during operation can be prevented from intermingling with Korotkoff sounds.

Blood pressure measurement system having a built-in microphone according to the present invention and the blood pressure measurement method using a built-in microphone, the measurement burden of the subject because the blood pressure is measured only by the cuff pressing the upper arm of the subject without wearing an additional sensor, etc. to measure the blood pressure Can be reduced.

The blood pressure measuring system having a built-in microphone and the blood pressure measuring method using the built-in microphone according to the present invention can accurately measure blood pressure because only Korotkoff sounds used for calculating blood pressure can be extracted.

 Blood pressure measurement system having a built-in microphone according to the present invention and a blood pressure measuring method using a built-in microphone is a microphone for detecting the Korotkoff sound according to the pressure change of the cuff is built in a structure separate from the cuff and the structure separate from the cuff Therefore, it is possible to prevent an error from occurring in the detection of the Korotkoff sound due to the noise caused by the cuff movement or the noise or noise around the cuff.

In the blood pressure measuring system having a built-in microphone and the blood pressure measuring method using the built-in microphone according to the present invention, even if the subject moves the upper arm with the cuff freely, noise is unlikely to be detected by the microphone due to the noise caused by the cuff movement. Therefore, the activity of the subject can be improved.

1 is a view schematically showing the configuration of a blood pressure measuring system having a built-in microphone according to an embodiment of the present invention.
2 is a flow chart showing the operation of the blood pressure measuring system according to an embodiment of the present invention.
3 is a flowchart illustrating a process of measuring blood pressure using a blood pressure measuring system according to an embodiment of the present invention.
4 is a graph showing the cuff pressure signal and the acoustic signal of the microphone obtained by using the blood pressure measuring system according to an embodiment of the present invention.
FIG. 5 is an enlarged graph of portion “A” of FIG. 4.
Figure 6 is a graph showing the Korotkoff sound and valve noise of the acoustic signal of the microphone obtained by using the blood pressure measurement system according to an embodiment of the present invention.
7 is a graph showing a Korotkoff sound extracted using the blood pressure measurement system according to an embodiment of the present invention.
8 is a graph showing the presence or absence of valve noise according to the use of the valve of the blood pressure measuring system according to an embodiment of the present invention.
9 is a graph showing the influence of the ambient noise when using the blood pressure measurement system according to an embodiment of the present invention.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to or limited by the embodiments. Like reference symbols in the drawings denote like elements.

1 is a view schematically showing the configuration of a blood pressure measuring system having a built-in microphone according to an embodiment of the present invention, Figure 2 is a flow chart showing the operation sequence of the blood pressure measuring system according to an embodiment of the present invention, 3 is a flowchart illustrating a process of measuring blood pressure using a blood pressure measuring system according to an embodiment of the present invention, and FIG. 4 is a cuff pressure signal and a microphone obtained using the blood pressure measuring system according to an embodiment of the present invention. 5 is a graph showing an acoustic signal of FIG. 5 is an enlarged graph of part “A” of FIG. 4, and FIG. 6 is a Korotkoff sound among acoustic signals of a microphone obtained using a blood pressure measuring system according to an embodiment of the present invention. And a graph showing the valve noise, Figure 7 is a graph showing the Korotkoff sound extracted using the blood pressure measurement system according to an embodiment of the present invention, Figure 8 Showing the valve noise, the presence or absence of the name of one embodiment of a valve used in the blood pressure measurement system in accordance with the example graph, Figure 9 is a graph showing the effect of noise when using a blood pressure measurement system in accordance with one embodiment of the present invention.

First, referring to FIG. 1, a blood pressure measuring system 100 having a built-in microphone according to an exemplary embodiment of the present invention is worn on the upper arm of a subject and has a cuff connected to a conduit 109 through which air is introduced or discharged. 101, a pump 104 connected to the conduit 109 to inject air into the cuff 101, a pressure sensor 120 connected to the conduit 109 to detect a pressure signal inside the cuff 101, a conduit The valve 103 and the conduit 109 connected to 109 to exhaust the air injected into the cuff 101 and inside the cuff 101 or conduit 109 when the air is exhausted from the cuff 101. It may include a microphone 105 for detecting the acoustic signal of.

In the figure, reference numeral 106 is an amplifier, 107 is a microcontroller, and 108 is a display 108 that visually shows the measured blood pressure.

Cuff 101 of the blood pressure measurement system 100 with a built-in microphone according to an embodiment of the present invention is a structure having a kind of air bag-like structure for pressing the upper arm of the subject and Velcro to be easily worn on the upper arm of the subject It is preferable to form the type.

The cuff 101 may be connected with a conduit 109 such that air may be introduced into the cuff 101 or air inside the cuff 101 may flow out of the cuff 101. The conduit 109 connected to the cuff 101 is the same as a kind of tube, and one end of the conduit 109 is connected to the cuff 101 and the other end to the measurement unit 110 of the blood pressure measurement system 100. Can be.

Here, the measurement unit 110 may be referred to as a structure corresponding to a kind of container in which a space for accommodating various components and the like is formed therein and protects the internal components from the outside. As shown in Figure 1, the blood pressure measurement system 100 according to an embodiment of the present invention has a structure in which the cuff 101 is connected to one end and the measurement unit 110 is connected to the other end based on the conduit 109 It can be said that there is a feature.

The pressure sensor 102, the valve 103, the pneumatic pump 104, the microphone 105, the amplifier 106, the microcontroller 107, the display 108, and the like may be mounted inside the measurement unit 110. have. In this case, the display 108 may not only be formed in the measurement unit 110 but also may be formed separately from the measurement unit 110 in a separate structure.

The pressure sensor 102, the valve 103, the pneumatic pump 104 and the microphone 105 mounted inside the measuring unit 110 may be connected to a plurality of branch pipes (not shown) in communication with the conduit 109. . That is, the pressure sensor 102, the valve 103, the pneumatic pump 104 and the microphone 105 may be formed to communicate with the conduit 109 to which the cuff 101 is connected. In particular, the microphone 105 is preferably connected to the opposite end of the conduit 109 to which the cuff 101 is connected.

The pneumatic pump 104 may introduce air into the cuff 101 through the conduit 109 to cause the cuff 101 to expand, thereby compressing the upper arm of the subject wearing the cuff 101. As such, the pneumatic pump 104 causes the cuff 101 to press the upper arm of the subject. When the cuff 101 is expanded by the operation of the pneumatic pump 104 to press the upper arm of the subject, the blood flow is temporarily blocked by pressing the upper arm artery.

The valve 103 is for exhausting air introduced into the cuff 101, and the air injected into the cuff 101 by the operation of the valve 103 may flow out through the conduit 109. By operating the valve 103, the cuff 101 can be depressurized and blood can begin to flow slowly as the artery of the upper arm pressed by the cuff 101 expands. It is preferable to reduce the pressure of the cuff 101 by a certain amount of pressure per unit time. The blood pressure measuring system 100 according to an embodiment of the present invention has a cuff by the valve 103 at a ratio of 2 to 3 mmHg / s. Depressurize (101).

At this time, the pressure sensor 102 installed in communication with the conduit 109 may detect a pressure signal or a degree of pressure change inside the conduit 109 when the cuff 101 is depressurized by the valve 103. . The pressure sensor 102 detects a change in pressure occurring inside the cuff 101 from the pressure of the air flowing through the conduit 109 when the inside of the cuff 101 is decompressed to a predetermined magnitude using the valve 103. Can be. The pressure sensor 102 can also detect pulsations caused by the heart while depressurizing the cuff 101. If there is no pulsation in the depressurization process of the cuff 101, the pressure signal inside the cuff 101 detected by the pressure sensor 102 can obtain a pressure signal that decreases almost linearly at a constant rate. However, in practice, a pulsation exists so that a pulsation signal in which the pressure increases at regular time intervals is present in the pressure signal. Indeed, when the heart pumps blood, there is a pulsation in the artery depressed by the cuff 101, which can cause the cuff 101 to be momentarily pressurized. The pressure sensor 102 can detect the pressure signal of the cuff 101 in which such pulsation exists.

The pressure sensor 102, the valve 103, the pneumatic pump 104 and the microphone 105 may be controlled to be operated by the microcontroller 107. For example, the cuff pressure signal detected by the pressure sensor 102 is sent to the microcontroller 107, the microcontroller 107 of the valve 103 or the pneumatic pump 104 based on the received pressure signal The operation can be controlled.

Here, the microphone 105 is provided spaced apart from the cuff 101, it is possible to detect the acoustic fluctuations due to the minute vibration or the change in the pressure inside the conduit 109 connected to the cuff 101. The microphone 105 is used to detect Korotkoff Sound, which is the basis of blood pressure measurement, so that acoustic components due to noise or noise generated around the cuff 101 are not detected by the microphone 105. The cuff 101 and the microphone 105 are preferably installed in a spatially separated structure.

To this end, in the blood pressure measuring system 100 according to an embodiment of the present invention, the microphone 105 is embedded in the same device 110 as the pump 104, the pressure sensor 102, and the valve 103. It can be formed in a built-in type. As such, by forming the microphone 105 inside the measurement unit 110, which is a separate structure spatially separated from the cuff 101, the accuracy of the microphone 105 is prevented from being lowered by the noise around the cuff 101. can do. The microphone 105 may be connected to a portion of the conduit 109 spaced apart from the portion where the cuff 101 is connected.

As shown in FIG. 1, the microphone 105 is preferably connected to the opposite end of the conduit 109 to which the cuff 101 is connected.

The microphone 105 may detect or detect an acoustic signal generated by the conduit 109 when the cuff 101 is decompressed, and in this process, a minute vibration or korotkov sound generated when there is a pulsation in the cuff pressure signal. Can be detected. Since the pressure of the cuff 101 is reduced by the operation of the valve 103, the microphone 105 may also detect an acoustic signal due to the operation sound of the valve 103 or the noise generated when the valve 103 is operated. That is, the microphone 105 may detect an acoustic signal generated when the valve 103 is operated and a korotkov sound generated by the cuff 101 among the acoustic signals inside the conduit 109.

On the other hand, the microphone 105 of the blood pressure measuring system 100 according to an embodiment of the present invention may use a condenser microphone. It is also possible to use electret condenser microphones.

The blood pressure measuring system 100 having a built-in microphone according to the present invention uses the microphone 105 built in the measurement unit 110 spaced apart from the cuff 101 in a section in which the valve 103 does not operate. Korotkoff sounds can be detected and used to calculate accurate blood pressure.

Referring to Figure 2 describes the operation of the blood pressure measuring system 100 with a built-in microphone according to an embodiment of the present invention.

The pneumatic pump 104 is operated to introduce air into the cuff 101 and pressurizes the cuff 101 (1100). When the pressurization of the cuff 101 is completed and the cuff 101 presses the artery of the upper arm, the valve 103 is operated to allow air to flow out of the cuff 101 to start depressurizing the cuff 101 ( 1200). At this time, the pressure of the cuff 101 is preferably reduced to 2 to 3 mmHg / s.

During the decompression of the cuff 101, the pressure sensor 102 detects a pressure signal of the cuff and also detects pulsation or pulse information included in the pressure signal. As such, the cuff pressure signal detected by the pressure sensor 102 may be signal processed to detect a pulsation waveform, and the valve operation prohibition section and the valve operation section may be calculated using the same (1300). A method of calculating the valve operation prohibition section by signal processing the cuff pressure signal will be described later.

As a result of the signal processing, it is determined whether to continue to operate the valve 103 or to repeat the valve operation prohibition period calculation process according to whether the valve operation prohibition section is in operation 1400. If the valve operation is not in the prohibition section, the valve 103 may be operated to continue depressurization of the cuff 101 (1500). When the depressurization of the cuff 101 is terminated using the valve 103 (1600), the voice signal recorded by the microphone 105 may be analyzed to extract the Korotkoff sound to calculate the blood pressure (1700). The calculated blood pressure may be displayed on the display 108 or the like (1800). Blood pressure measurement system 100 having a built-in microphone according to an embodiment of the present invention can be operated in the same order as described above. Hereinafter, a process of calculating a valve operation prohibition section / valve operation section by processing a cuff pressure signal or a sound signal recorded by a microphone and extracting a Korotkoff sound will be described.

Referring to FIG. 3, in the method of measuring blood pressure using the blood pressure measuring system 100 having a built-in microphone according to an embodiment of the present invention, the cuff 101 is pressurized using a pump 104. Step 2100, depressurizing the cuff 101 at a constant pressure per unit time using the valve 103 after completion of pressurization of the cuff 101 (2200), and pressure sensor 102 while depressurizing the cuff 101. Detecting (2300) the pressure signal of the cuff (101), detecting the acoustic signal inside the conduit (109) using the microphone (105) while depressurizing the cuff (101), and the cuff ( 101, calculating the operation prohibition period of the valve 103 by analyzing the pressure signal (2500), extracting the Korotkoff sound from the acoustic signal detected by the microphone 105 according to whether the valve operation prohibition period (2600) ) And systolic and diastolic blood pressure from Korotkoff sound It may provide a blood pressure measurement method using a built-in microphone, comprising the step 2700 of calculating.

Pressing the cuff 101 using the pneumatic pump 104 (2100) may be performed by introducing air into the cuff 101 through the conduit 109 using the pneumatic pump 104 as described above. have. As the cuff 101 is pressed, the upper arm of the subject wearing the cuff 101 may be pressed to block blood flow through the artery.

When the pressurization of the cuff 101 is completed, the operation of the pneumatic pump 104 is stopped by the microcontroller 107, and the microcontroller 107 operates the valve 103 to depressurize the cuff 101 to reduce the pressure. Begin (2200). As mentioned above, the step 2200 of depressurizing the cuff 101 controls the valve 103 to depressurize to 2-3 mmHg / s, but it is not necessary to depressurize to this pressure magnitude.

When the cuff 101 is depressurized, air flows out through the conduit 109. In this process, the pressure inside the cuff 101 changes. The pressure sensor 102 detects a signal according to the pressure change inside the cuff. (2300).

Here, the step 2300 of detecting the signal due to the pressure change inside the cuff 101 by the pressure sensor 102 while depressurizing the cuff 101 is to uniformly depress the cuff 101 by the valve 103. The pulsation generated in the process can be detected.

Referring to FIG. 4, the cuff pressure detected by the pressure sensor 102 (see graph indicated by Cuff Pressure), the acoustic signal detected by microphone 105 (see graph indicated by Acoustic signal from the condenser microphone), piezo A graph of a reference sound signal obtained by a microphone (not shown) is shown. In FIG. 4, the horizontal axis represents time (unit: seconds) and the vertical axis represents pressure. In the graph showing the cuff pressure, it can be seen that the cuff 101 is pressurized until 5 seconds when the pressure increases up to 5 seconds. After 5 seconds, the pressure continuously decreases, and it can be said that the step 2200 of depressurizing the cuff 101 is performed after 5 seconds. The cuff pressure graph after 5 seconds shows that there is a ripple over an almost constant time interval, which is caused by pulsation.

A detailed description will be made with reference to FIG. 5 in which the "A" portion of FIG. 4 is enlarged.

Detecting a signal according to the pressure change inside the cuff 101 by the pressure sensor 102 while depressing the cuff 101 may occur at regular intervals in the pressure inside the cuff 101 which is constantly decreasing. It is possible to detect a pressure signal with a pulsation or a signal according to a pressure change.

If there is no pulsation, the pressure sensor 102 will only detect the pressure signal when the internal pressure of the cuff 101 is constantly reduced, and the pressure signal at this time is the cuff pressure graph of FIG. 5. You will get a graph of pressure signal that decreases per hour in a similar fashion to a straight line connecting P1, P3, and P5. However, as shown in FIG. 5, the pressure signal graph actually detected does not have a constant pressure drop, and a pressure signal graph is obtained in which the pressure increases at almost constant time intervals. Here, the point where the pressure increases, such as P2, P4, P6 in the cuff pressure signal may be referred to as the point where the pulsation occurred. In fact, when the heart pumps blood, the pulsation is present in the artery pressed by the cuff 101, which causes the cuff 101 to be momentarily pressurized, so that the pressure sensor 102 of the cuff 101 has such a pulsation. The pressure signal is detected.

As described above, by detecting the cuff pressure signal reflecting the pulsation in the step 2300 of detecting the signal according to the pressure change inside the cuff 101 by the pressure sensor 102 while depressing the cuff 101, the Korotkoff The valve operation prohibition section can be calculated from the cuff pressure signal reflecting the region where the sound exists and the pulsation.

The pulsation is added to the pressure inside the cuff 101 which is constantly reduced by the valve 103, so that an inflection point may appear in the waveform of the pressure signal inside the cuff 101. As shown in FIG. 5, the cuff pressure graph shows that the pressure is constantly reduced until 22.4 seconds and increases in pressure from 22.4 seconds to approximately 22.6 seconds. That is, the cuff pressure graph may be said to have a tangential slope with respect to the waveform of the cuff pressure signal until 22.4 seconds, but the tangential slope with respect to the waveform of the cuff pressure signal decreases from 22.4 seconds to 22.6 seconds. Therefore, it can be said that the cuff pressure signal waveform has a first inflection point P1 at a point of 22.4 seconds. After 22.6 seconds, the tangential slope begins to change again with respect to the waveform of the cuff pressure signal as the cuff pressure decreases. Therefore, it can be said that the cuff pressure signal waveform has a second inflection point P2 at a point of 22.6 seconds.

Here, it can be said that the cuff pressure change from the first inflection point P1 to the second inflection point P2 is caused by pulsation.

When the cuff pressure decreased from 22.6 seconds to about 23.1 seconds, the pressure starts to increase again, and at 23.1 seconds, the first inflection point P3 at which the tangential slope of the cuff pressure signal waveform changes again appears. The cuff pressure, which then increased to approximately 23.3 seconds, begins to decrease after 23.3 seconds. Therefore, it can be said that the second inflection point P4 at which the slope of the tangent of the waveform of the cuff pressure signal changes at a time point of 23.3 seconds appears.

Thus, the waveform change of the cuff pressure signal in which the first inflection point P1, P3, P5 and the second inflection point P2, P4, P6 appear continuously occurs. However, the magnitude of the pressure of the second inflection point P2, P4, P6 will decrease with time.

As described above, the step 2500 of analyzing the cuff pressure signal and calculating the operation prohibition section of the valve includes the first inflection points P1, P3, and P5 in which the slope of the tangent changes from increasing to decreasing with respect to the waveform of the cuff pressure signal; The second inflection points P2, P4, and P6 whose slopes of the tangent line change from decreasing to increasing can be obtained. Here, in FIG. 5, three first inflection points and three second inflection points are displayed for convenience of description, but three or more first and second inflection points may be displayed.

As described above, the step 2500 of calculating the operation prohibition interval of the valve may be performed by analyzing waveforms of the cuff pressure signals to obtain first inflection points P1, P3, P5 and second inflection points P2, P4, and P6. In addition, the valve operation prohibition section K may be calculated by adding a predetermined time K2 to a time corresponding to the second inflection point.

That is, the step 2300 of analyzing the cuff pressure signal and calculating the operation prohibition section of the valve may include a time interval K1 between a first inflection point P1, P3, P5 and a second inflection point P2, P4, P6. ) And the time interval K, which is the sum of the predetermined time interval K2 added to the time corresponding to the second inflection point P2, P4, P6, may be calculated as the valve operation prohibition period K.

Referring to FIG. 5, the valve operation prohibition section K may include a time interval or a time interval including a constant left and right intervals based on a region in which a pulsation exists (ie, a second inflection point with a large pressure) in the waveform of the cuff pressure signal. It can be calculated as an operation prohibition period.

On the other hand, the step (2500) of calculating the operation prohibition section of the valve by analyzing the cuff pressure signal may be defined as a section between the valve operation prohibition period. That is, as shown in Figure 6, it can be said that the valve operating section (V) is present between the valve operation prohibition section (K) including a section having a pulsation. In the valve operation prohibition section K, the Korotkoff sound is not accurately detected by the noise generated when the valve 103 is operated in the Korotkoff sound by not operating the valve 103 for depressurizing the cuff 101. You can prevent it from failing.

Referring to FIG. 5, it can be seen that the Korotkoff sound C of the acoustic signal detected by the microphone 105 exists in the valve operation prohibition section K. FIG.

That is, the step 2600 of extracting the Korotkoff sound from the sound signal detected by the microphone according to the valve operation prohibition section corresponds to the valve operation prohibition section K among the sound signals detected by the microphone 105. The sound signal in the time domain can be extracted. To this end, detecting 2400 an acoustic signal inside the conduit 109 may be performed while depressurizing the cuff 101.

Referring to FIG. 6, there is shown a graph of the cuff pressure signal waveform over time and the acoustic signal waveform detected by the microphone 105. In the time section corresponding to the valve operation prohibition section K, the Korotkoff sound D is present, and in the valve operation section V, the acoustic signal E generated by the operation of the valve 103 is present. At this time, since the sound signal existing by the operation of the valve 103 may act as noise in extracting the Korotkoff sound, the sound of the Korotkoff sound and the operation of the valve from the sound signal obtained from the microphone 105. It is important to distinguish or separate the signal, in one embodiment of the present invention by analyzing the cuff pressure signal obtained from the pressure sensor 102 to calculate the valve operation prohibition section (K) and the valve operation section (V), microphone 105 The Korotkoff sound can be extracted from the sound signal existing in the valve operation prohibition section (K) from the sound signal obtained by

Extracting a Korotkoff sound from the sound signal detected by the microphone according to whether the valve operation prohibition period (2600) has a relatively large amplitude among the sound signals in the time domain corresponding to the valve operation section (V). The sound signal may be defined as a Korotkoff sound (D).

In addition, the step 2600 of extracting the Korotkoff sound from the acoustic signal detected by the microphone according to whether the valve operation is prohibited is generated when the valve 103 is operated from the acoustic signal detected by the microphone 105. The acoustic signal can be eliminated. That is, by selecting only the sound signal corresponding to the valve operation prohibition section (K) and not the sound signal existing in the valve operation section (V), it is possible to easily remove the sound signal generated when the valve 103 is operated. have.

FIG. 7 is a graph showing only the Korotkoff sound calculated in the valve operation prohibition section K and showing it over time. Referring to FIG. 7, it can be seen that the amplitude or magnitude of the Korotkoff sound gradually decreases with time. The systolic and diastolic blood pressures can be calculated from the change in the size of the Korotkoff sound (2700).

8 is a graph showing the presence or absence of valve noise according to the use of the valve of the blood pressure measuring system according to an embodiment of the present invention. In FIG. 8A, valve noise is not detected because the valve is not operated. However, valve noise is detected because the valve is operated. In this way, the presence or absence of valve noise varies depending on whether the valve is operated or not, so that the valve operation prohibition section (K) and the valve operation section (V) are calculated separately to exclude the influence of the valve and to accurately select only the Korotkoff sound. Can be calculated.

9 is a graph showing the influence of the ambient noise when using the blood pressure measurement system according to an embodiment of the present invention. The graph of FIG. 9 includes cuff pressure (top graph), extracted signal from the acoustic signal (center graph), and piezo microphone (not shown) when the cuff 101 is depressurized. The acoustic signal (Reference Microphone, bottom graph) obtained by is shown for each time. First, the graph showing the cuff pressure tends to decrease gradually with time, and the acoustic signal obtained by the microphone 105 represents an acoustic signal whose amplitude increases at a substantially constant time interval. It's a cope sound. The acoustic signal obtained by the piezo microphone includes not only a signal corresponding to the Korotkoff sound obtained by the microphone 105, but also other acoustic signals, and the other acoustic signals include noises around the piezo microphone or human voice. It can be seen that other noise components are included in addition to the desired Korotkoff sound. In contrast, it can be seen that the microphone 105 according to an embodiment of the present invention detects only a desired Korotkoff sound and no other noise component. Since the microphone 105 according to the exemplary embodiment of the present invention is installed in a form in which the cuff 101 and the measurement unit 110 are spatially or structurally separated, the microphone 105 is not affected by the noise around the cuff 101. .

As described above, according to the blood pressure measuring system 100 having a built-in microphone according to an embodiment of the present invention and a blood pressure measuring method using a built-in microphone, the cuff 101 is structurally separated from the cuff 101. Since the microphone 105 detects a pressure change or an acoustic signal when the cuff 101 is depressurized, the problem of failing to accurately detect the Korotkoff sound due to the noise generated during the operation of the valve 103 may be solved. .

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

100: blood pressure measurement system 101: cuff
102: pressure sensor 103: valve
104: pneumatic pump 105: microphone
107: microcontroller 108: display
109: conduit 110: measuring unit

Claims (14)

A cuff worn on the upper arm of the subject and connected to a conduit through which air is introduced or discharged;
A pump connected to the conduit for injecting air into the cuff;
A pressure sensor connected to the conduit to detect a pressure signal inside the cuff;
A valve connected to the conduit to exhaust the air injected into the cuff to reduce the cuff; And
And a microphone connected to the conduit to detect an acoustic signal inside the cuff or the conduit when air is exhausted from the cuff.
The microphone is provided spatially spaced apart from the cuff and minute vibrations inside the conduit generated when there is a pulsation in the corotcop sound generated in the conduit or the pressure signal inside the cuff when the cuff is decompressed. Detect
The pressure sensor detects a pulsation included in the pressure signal and calculates an operation prohibition section and an operation section of the valve.
The method of claim 1,
And the microphone is embedded in the same unit as the pump, the pressure sensor, and the valve to prevent the accuracy of the microphone from being degraded by noise around the cuff.
The method of claim 2,
And the microphone detects an acoustic signal generated during operation of the valve and a Korotkoff sound generated by the cuff among the acoustic signals inside the conduit.
The method of claim 2,
The microphone is a blood pressure measuring system having a built-in microphone, characterized in that connected to the part of the conduit, the cuff is connected as far as possible.
5. The method according to any one of claims 1 to 4,
The microphone is a blood pressure measurement system having a built-in microphone, characterized in that the condenser microphone.
In the method for measuring blood pressure using the blood pressure measuring system according to claim 5,
Pressing the cuff using the pump;
Depressurizing the cuff at a constant pressure per unit time using the valve after the pressurization of the cuff is completed;
Detecting a pressure signal of the cuff by the pressure sensor while depressurizing the cuff;
Detecting an acoustic signal inside the conduit using the microphone while depressurizing the cuff;
Calculating an operation prohibition period of the valve by analyzing the cuff pressure signal;
Extracting a Korotkoff sound from the sound signal detected by the microphone according to whether the valve operation is prohibited; And
Computing the systolic and diastolic blood pressure from the Korotkoff sound; Blood pressure measurement method using a built-in microphone comprising a.
The method according to claim 6,
The step of detecting the pressure signal of the cuff by the pressure sensor while decompressing the cuff is a blood pressure measurement using a built-in microphone, characterized in that to detect the pulsation generated in the process of depressurizing the cuff constantly by the valve Way.
The method of claim 7, wherein
The detecting of the pressure signal of the cuff by the pressure sensor during the depressurization of the cuff may include detecting the pulsation plus pressure signal which appears at regular intervals to the pressure inside the cuff which is constantly decreasing. Blood pressure measurement method using.
9. The method of claim 8,
A method of measuring blood pressure using a built-in microphone, characterized in that the inflection point appears in the waveform of the pressure signal by adding the pulsation to the pressure inside the cuff which is constantly decreasing.
10. The method of claim 9,
Analyzing the cuff pressure signal to calculate the operation prohibition section of the valve includes: a first inflection point at which a tangential slope changes from increasing to decreasing with respect to a waveform of the cuff pressure signal; Blood pressure measurement method using a built-in microphone, characterized in that to obtain the inflection point.
The method of claim 10,
The calculating of the operation prohibition section of the valve by analyzing the cuff pressure signal may include a time interval obtained by adding a time interval between the first inflection point and the second inflection point and a predetermined time interval added to the time corresponding to the second inflection point. Blood pressure measurement method using a built-in microphone, characterized in that for calculating the valve operation prohibition period.
The method of claim 11,
And calculating the operation prohibition section of the valve by analyzing the cuff pressure signal, wherein a section between the valve operation prohibition sections is defined as a valve operation section.
The method of claim 12,
The extracting of the Korotkoff sound from the sound signal detected by the microphone according to whether the valve operation prohibition section is performed may be performed by extracting the sound signal in the time domain corresponding to the valve operation prohibition section from the sound signal detected by the microphone. Blood pressure measurement method using a built-in microphone, characterized in that.
The method of claim 13,
The extracting of the Korotkoff sound from the sound signal detected by the microphone according to whether the valve operation prohibition section is performed may be performed by generating a corot sound signal having a relatively large amplitude from among the sound signals in the time domain corresponding to the valve operation prohibition section. Blood pressure measurement method using a built-in microphone, characterized in that defined by the sound.

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