JP6474299B2 - Pulse wave measuring device - Google Patents

Description

  The present invention relates to a pulse wave measuring device that is attached to a human body and measures a pulse wave of the human body, in particular, a pressure pulse wave indicating a pressure wave of an arterial blood vessel.

  Currently, various methods have been proposed for monitoring cardiac function. For example, an electrocardiograph that detects the movement of the heart from the potential of the myocardium, a sphygmomanometer that detects the pressure at which the heart pumps blood throughout the body, a plethysmograph that detects volume changes in blood vessels, and a blood that detects the flow rate of blood An anemometer is an example. The application destination of such a device is not limited to the medical field for diagnosing cardiovascular function. For example, cardiac function monitoring is expected to be applied to a wide range of uses, such as detection of driver drowsiness and abnormal cardiac function, management of sports training status, monitoring of the elderly and disease prognosis (monitoring sudden changes in medical conditions), etc. It is.

  Among these cardiac function monitoring techniques, the ability to actually measure the ability of the heart to eject blood is a technique for detecting pressure pulse waves. The pressure pulse wave is a pressure wave transmitted to the arterial blood vessel, and indicates the ability (pressure) of the heart to expand and contract to push blood into the artery and the pressure reflected from the blood vessel wall. Knowing the amount of blood that the heart pushes out (the amount of ejection) by integrating the pressure pulse wave information (measurement data that measures the pressure pulse wave) obtained during the heart contraction period (period during which the heart pumps out blood) Can do.

  As a method of detecting pressure pulse waves, a method of actually measuring pressure by inserting a catheter into an artery, a method of detecting a pressure change transmitted from the artery to the human body surface by pressing the arterial part from the outside of the human body, and There is. The method of inserting a catheter has problems such as limitation of movement of the measurement subject and risk of infection because of the invasive method. For this reason, it is limited to the medical diagnosis use in an inspection organization or a hospital. On the other hand, in order to continue to accurately detect the pressure pulse wave with the pressing method, a mechanism that always presses the human body with a constant pressing force is indispensable (see Patent Document 1).

JP 2000-245702 A

  In order to accurately detect a pressure change (pressure pulse wave) transmitted from the artery to the body surface as pressure pulse wave information, it is essential to first press a high-resolution pressure sensor with a constant pressing force. Although the pressure force is constant, the pressure wave transmitted from the body can be accurately detected, but the pressure change outside the human body, that is, the change in atmospheric pressure is added to the pressure pulse wave and detected as pressure pulse wave information. . For example, if the person being measured is a car driver, the atmospheric pressure inside the car changes greatly due to the opening and closing of doors and windows, the passing of oncoming cars, the weather outside the car (strong winds), etc. Detects pressure pulse wave information. It is difficult to determine whether or not the pressure pulse wave information obtained at the time of such atmospheric pressure fluctuation is accurate information, and there is a problem that an erroneous determination is made from incorrect pressure pulse wave information.

  Furthermore, such a change in atmospheric pressure is very small relative to the absolute value of atmospheric pressure. For this reason, there is a problem that it cannot be performed with insufficient accuracy to detect and remove the fluctuation of atmospheric pressure from the pressure pulse wave information using a general absolute pressure sensor or the like installed around the measurement subject. It was.

  Therefore, an object of the present invention is to provide a pulse wave measuring device capable of detecting accurate pressure pulse wave information even if there is a change in atmospheric pressure around the measurer.

  In order to solve the above-mentioned problem, a first feature of the present invention is a pulse wave measuring device that measures a pressure pulse wave that is a pressure wave transmitted through an arterial blood vessel, and is a cavity that communicates with the outside and has a flexible bottom surface. Based on the output of the differential pressure sensor, and a differential pressure sensor that outputs a signal related to the differential pressure between the internal pressure and the atmospheric pressure of the cavity in a state where the bottom surface of the cavity is in contact with the skin, A calculation processing unit that calculates pressure pulse wave information, a pulse wave verification unit that detects verification pulse wave information related to at least one of myocardial potential, volume pulse wave, and blood flow velocity, and the pressure pulse wave information A waveform synchronization processing unit to which the verification pulse wave information is input, and the waveform synchronization processing unit compares the verification pulse wave information with the pressure pulse wave information and selects the pressure pulse wave information. Output.

  According to the present invention, it is possible to provide a pulse wave measuring device capable of detecting accurate pressure pulse wave information from which an atmospheric pressure fluctuation is removed even if there is an atmospheric pressure fluctuation.

  In addition, the second feature of the present invention is that the waveform synchronization processing unit detects a time difference between the verification pulse wave information and the pressure pulse wave information, and then detects the verification pulse wave information and the pressure pulse wave information. A synchronization process is performed.

  According to the present invention, since the time synchronization between the pressure pulse wave information and the verification pulse wave information can be accurately performed, it is possible to detect accurate pressure pulse wave information from which the atmospheric pressure fluctuation is removed even if there is atmospheric pressure fluctuation. A pulse wave measuring device capable of being provided can be provided.

  Further, the third feature of the present invention is that the waveform synchronization processing unit selects and outputs only the pressure pulse wave information similar to the normal waveform recorded in advance among the pressure pulse wave information subjected to the synchronization processing. It is characterized by that.

  According to the present invention, since the normal waveform can be determined from the pressure pulse wave information, accurate pressure pulse wave information can be detected.

  A fourth feature of the present invention is that the waveform synchronization processing unit is obtained by averaging the similar waveforms when a plurality of similar waveforms are obtained from the pressure pulse wave information subjected to the synchronization processing. Only the pressure pulse wave information similar to the waveform is selected and output.

  According to the invention, although the pressure pulse wave information varies among individuals, the pressure pulse wave information depending on the measurement subject can be obtained from the averaging process, so that accurate pressure pulse wave information can be detected.

  According to a fifth aspect of the present invention, a cardiac function is determined based on the pressure pulse wave information output from the waveform synchronization processing unit.

  According to the present invention, since the cardiac function is determined from accurate pressure pulse wave information, more accurate cardiac function determination can be performed.

  According to a sixth aspect of the present invention, when the skin pulsates, the arithmetic processing unit calculates a differential pressure between the internal pressure and the atmospheric pressure of the cavity based on an output signal of the differential pressure sensor. A differential pressure calculation unit for calculating the internal pressure of the cavity based on the differential pressure calculated by the differential pressure calculation unit and the atmospheric pressure, and a differential pressure calculated by the differential pressure calculation unit. Based on the number of moles of air flow that calculates the number of moles of air flowing between the outside and the cavity, and the number of moles of flow calculated by the number of moles of air flow calculated by the air flow number of moles calculation unit, Based on the air mole number calculation unit for calculating the air mole number, the air mole number calculated by the air mole number calculation unit, and the internal pressure of the cavity calculated by the cavity internal pressure calculation unit, the volume in the cavity is calculated. And volume calculation unit for output, characterized in that it comprises a displacement calculating unit for calculating a time displacement of the skin based on the volume of the cavity which is calculated by the volume calculating unit.

  Further, a seventh feature of the present invention is that the arithmetic processing unit has a circulation mole number database section that stores in advance the circulation mole number of the air corresponding to the magnitude of the differential pressure, and the number of moles of air circulation. The calculation unit extracts the number of moles of air flow corresponding to the magnitude of the differential pressure calculated by the differential pressure calculation unit from the circulation mole number database unit.

  In addition, an eighth feature of the present invention is that the flow mole number database unit previously obtains a relationship between a pressure difference at both ends of the cavity and a flow rate of air by numerical calculation, and the relationship and the pressure difference are calculated. Based on the above, it is generated by calculating the number of moles of air flow.

  Further, a ninth feature of the present invention includes an air temperature acquisition unit that acquires the temperature information of the air, and the air mole number calculation unit is configured to determine the air in the cavity based on the temperature information and the flow mole number. The number of moles is calculated.

  The tenth feature of the present invention is characterized by having an atmospheric pressure obtaining unit for obtaining the atmospheric pressure.

  Further, an eleventh feature of the present invention is a strain detection unit that detects a displacement amount due to strain of a side wall of the cavity, and the volume calculation unit uses the displacement amount detected by the strain detection unit. The volume inside is calculated.

  According to the present invention, it is possible to detect accurate pressure pulse wave information by converting a pressure pulse wave, which is a pressure wave transmitted from an arterial blood vessel in the body, to the internal pressure of the cavity via the vibration of the skin.

  Therefore, the present invention can provide a pulse wave measuring device that can detect accurate pressure pulse wave information even if there is atmospheric pressure fluctuation.

It is a mimetic diagram showing a schematic structure of pulse wave measuring device 1 concerning a 1st embodiment of the present invention. It is a schematic diagram which shows schematic structure of the pressure pulse wave measurement part 10 of FIG. It is a block diagram of the pressure pulse wave measurement part 10 of FIG. FIG. 2 is a block diagram of a pulse wave verification unit 50 in FIG. 1. It is sectional drawing of the differential pressure sensor 5 shown in FIG. It is a flowchart which shows the flow of a function of the pressure pulse wave measurement part 10 concerning the 1st Embodiment of this invention. It is a "reference table of differential pressure and air inflow" according to the first embodiment of the present invention. 3 is a graph showing pressure pulse wave information and an electrocardiographic signal obtained by the pressure pulse wave measuring device 1. 3 is a graph showing pressure pulse wave information and an electrocardiogram signal at rest obtained by the pressure pulse wave measuring device 1. It is a block diagram of the pulse wave verification unit 250 according to the second embodiment of the present invention. It is a flowchart which shows the flow of a function of the pulse wave measuring device 1 concerning the 3rd Embodiment of this invention. It is a flowchart which shows the flow of the function of the pulse-wave measuring apparatus 1 concerning the 4th Embodiment of this invention. It is a flowchart which shows the flow of the function of the pulse-wave measuring apparatus 1 concerning the 5th Embodiment of this invention.

  Hereinafter, embodiments of a pulse wave measuring apparatus according to the present invention will be described with reference to the drawings.

(First embodiment)
(overall structure)
FIG. 1 shows a configuration of a pulse wave measuring apparatus 1 according to the first embodiment of the present invention. In the present embodiment, the pulse wave measuring device 1 includes a pressure pulse wave measuring unit 10 attached to the wrist and a pulse wave verifying unit 50 attached to the chest.
FIG. 2 shows the configuration of the pressure pulse wave measurement unit 10. The pressure pulse wave measurement unit 10 has a form similar to that of a wristwatch, and includes a device main body 3 and a band 2 fixed to a side surface of the device main body 3.

The band 2 is composed of, for example, an annular elastic material or the like, and the apparatus main body 3 is attached so as to be in close contact with the user's skin 4.
The apparatus main body 3 has a differential pressure sensor 5 in the lower part (skin 4 side). The differential pressure sensor 5 has a lower part in close contact with the skin 4 and an upper part communicating with the outside air through the opening 6. The structure of the differential pressure sensor 5 will be described in detail later. The apparatus body 3 has a control board 7 on which elements having various functions to be described later are mounted.

FIG. 3 shows a block diagram of the pressure pulse wave measurement unit 10. In addition to the differential pressure sensor 5, the pressure pulse wave measurement unit 10 corresponds to the control board 7, a control unit 11, a power source 12, a storage unit 13, an arithmetic processing unit 14, a communication unit 60, and a determination unit 70. And have.
The control unit 11 includes, for example, a CPU, a ROM, and the like, and comprehensively controls driving of the entire apparatus body 3.
The power source 12 is a power source such as various primary batteries such as dry batteries and secondary batteries such as batteries, and supplies power to each unit provided in the apparatus main body 3.

The storage unit 13 includes, for example, various nonvolatile memories and stores a drive program executed by the control unit 11, various data, and a reference table described later.
The arithmetic processing unit 14 includes a differential pressure calculation unit 15 that calculates a differential pressure based on the output of the differential pressure sensor 5, a cavity internal pressure calculation unit 16 that calculates an atmospheric pressure inside the cavity of the differential pressure sensor 5 described later, An air circulation mole number calculation unit 17 that calculates the number of moles of air flowing through the cavity, an air mole number calculation unit 18 that calculates the number of moles of air in the cavity, and a volume calculation unit that calculates the volume of the cavity. 19 and a displacement calculator 20 that calculates the displacement of the skin due to pulsation. The function of each unit included in the arithmetic processing unit 14 will be described in detail later (on the displacement calculation flow).

  The communication unit 60 is a communication device that transmits / receives information to / from the outside of the pressure pulse wave measurement unit 10 and includes, for example, a specific low-power radio, Bluetooth (registered trademark), or the like. Transmission / reception is performed mainly with the pulse wave verification unit 50, but transmission / reception with a smartphone held by the measurement subject or information communication with an external server or the like via another communication service is also possible.

The determination part 70 is comprised including CPU, ROM, etc., for example. A plurality of input signal information is compared with each other, and finally output of results of normal pressure pulse wave information and cardiac function determination of the measurement subject is performed.
FIG. 4 shows the configuration of the pulse wave verification unit 50. The pulse wave verification unit 50 includes an electrocardiogram detection unit 51 attached to the chest of the measurement subject with a belt 52.

The electrocardiogram detection unit 51 includes an electrocardiogram sensor 53, a power source 54, a processing unit 55, a storage unit 56, and a communication unit 57 therein.
The electrocardiographic sensor 53 detects the myocardial potential from the potential of the electrode brought into close contact with the skin.
The power source 54 is, for example, a power source such as various primary batteries such as a dry battery or a secondary battery such as a battery, and supplies power to each unit included in the electrocardiogram detection unit 51.

The processing unit 55 includes, for example, a CPU, a ROM, and the like, and comprehensively controls driving of the entire electrocardiogram detection unit 51.
The storage unit 56 includes, for example, various non-volatile memories and stores a drive program executed by the processing unit 55, various data, and the like.
The communication unit 57 is a communication device that transmits and receives information between the electrocardiogram detection unit 51 and the pressure pulse wave measurement unit 10, and includes, for example, a specific low-power radio, Bluetooth (registered trademark), or the like.

(Configuration of differential pressure sensor)
Next, the configuration of the differential pressure sensor 5 will be described. 5A and 5B are cross-sectional views of the differential pressure sensor 5. FIG. 5A shows a cross-section at time T0 representing the initial state, and FIG. 5B shows a cross-section at time T1 when skin pulsation occurs after time T0. The differential pressure sensor 5 includes, for example, a sensor frame 31 that is a frame having a square shape when viewed from above, and a cantilever 32 that protrudes in a cantilever manner with the upper surface of the sensor frame 31 as a base end. And having. The differential pressure sensor 5 is a space formed by the sensor frame 31 (side wall) and the skin portion 33 (flexible bottom surface) by closely contacting the skin portion 33 that is displaced by pulsation in the user's skin. A cavity 34 is formed.

  Although not shown, the lower portion of the cavity 34 is not necessarily opened in a state of being separated from the user's skin, and a flexible thin film that is in close contact with the skin portion 33 is fixed to the lower surface of the sensor frame 31. You may keep it.

  Here, the volume, pressure, and the number of moles of air inside the cavity 34 are V, Pin, and N, respectively, and V (0), Pin (0), Let N (0), V (1), Pin (1), and N (1).

(Differential pressure sensor structure and operation)
Next, a specific structure of the differential pressure sensor 5 will be described with reference to FIG. The differential pressure sensor 5 has a through hole surrounded by a sensor frame 31, and most of the mouth on the upper side is covered with a cantilever 32. The cantilever 32 is a substantially rectangular plate-like beam made of extremely thin Si of about 300 nm, for example, and one end is fixed to the sensor frame 31. The cantilever 32 has a side of, for example, a size of about 100 microns.

Since the vicinity of the fixed end of the cantilever 32 functions as a piezoresistor by doping impurities such as P (phosphorus) only in the vicinity of the upper surface, a remarkable piezoresistive effect is exhibited. A small gap of about 1 micron is formed between the side surface of the cantilever 32 and the sensor frame 31, and air flows between the outside air and the cavity 34 through the gap. Since only one end of the cantilever 32 is fixed, the cantilever 32 can be bent even with a slight force as compared with a diaphragm sensor that is fixed at the entire periphery, and functions as a highly sensitive sensor.
Here, as shown in FIG. 5B, it is assumed that the skin portion 33 is displaced downward at time T1 due to the pulsation of the lower artery. Then, the volume V inside the cavity increases and the atmospheric pressure Pin decreases. As a result, the cantilever 32 bends downward due to the differential pressure between the atmospheric pressure Pin and the external atmospheric pressure. Then, since the electric resistance value of the piezoresistive element built in the cantilever 32 changes, the differential pressure sensor 5 outputs a signal corresponding to the bending amount of the cantilever 32 via a bridge circuit (not shown). .

  Here, the relationship between the amount of bending of the cantilever 32 and the pressure difference (differential pressure) inside and outside the cavity 34 is measured in advance and stored in the storage unit 13 as a “piezoresistance value and differential pressure reference table”. Therefore, the differential pressure calculation unit 15 can calculate the differential pressure from the output signal of the differential pressure sensor 5 and the reference table of the storage unit 13.

  Further, when the pressure Pin in the cavity 34 decreases, air flows from the outside air into the cavity 34. At this time, the amount of the inflow of the air expressed in moles is ΔN. Thus, when the skin part 33 is displaced, V, Pin, and N all change. The relationship between the differential pressure and ΔN is acquired in advance by an experiment in which a flow meter is incorporated in the pressure pulse wave measurement unit 10 or a computer simulation in which the relationship between displacement of the cantilever 32 and air inflow / outflow is coupled. It is stored in the storage unit 13 as a “differential pressure and air inflow amount reference table”.

(Pressure pulse wave information calculation flow)
Next, the flow of pressure pulse wave information calculation by the pressure pulse wave measurement unit 10 according to the first embodiment of the present invention will be described with reference to an explanatory diagram (flowchart) shown in FIG. The case where the atmospheric pressure does not change and is in a constant state will be described.

  First, at time T0 representing the initial state, the volume V (0) in the cavity 34 is known from the design dimensions of the sensor frame 31. The pressure Pin (0) in the cavity 34 is the same as the atmospheric pressure. Therefore, the air mole number calculation unit 18 can obtain the mole number N (0) = Pin (0) V (0) / RK from the gas state equation PV = NRK using the temperature K (STEP 1). The temperature K and the atmospheric pressure are based on a control signal from the control unit 11 and are connected to the pulse wave measuring device 1 or provided in the pulse wave measuring device 1 or a pressure for absolute pressure measurement. A sensor (not shown) transmits the signal as an electrical signal to the arithmetic processing unit 14 (number-of-air calculating unit 18).

  Next, after the pulse wave measuring device 1 starts measuring displacement, the skin portion 33 is displaced by pulsation at time T 1, the cantilever 32 is bent, and a signal related to the piezoresistance value is sent from the differential pressure sensor 5 to the arithmetic processing unit 14. It is output (STEP 2).

  Next, the differential pressure calculation unit 15 refers to the “piezoresistance value and differential pressure reference table” stored in the storage unit 13 and calculates the differential pressure from the piezoresistance value. The cavity pressure calculation unit 16 calculates the pressure Pin (1) in the cavity 34 by subtracting the calculated differential pressure from the atmospheric pressure assuming that the atmospheric pressure is constant (STEP 3).

  Next, the air circulation mole number calculation unit 17 refers to the “reference table of differential pressure and air inflow amount” stored in the storage unit 13 and calculates the air inflow amount ΔN from the differential pressure calculated in STEP 3. (STEP 4). Here, the “reference table of differential pressure and air inflow amount” is, for example, as shown in FIG. 7, the value of air inflow amount Q per unit time (mol / sec) according to the value of differential pressure ΔP (Pa). Is tabulated in accordance with the magnitude of the differential pressure ΔP.

  Next, the air mole number calculation unit 18 adds the air inflow amount ΔN calculated in STEP 4 to the air mole number N (0) at the time T0, so that the air mole number N (( 1) is calculated (STEP 5).

  Next, the volume calculation unit 19 substitutes Pin (1) calculated in STEP 3 and N (1) calculated in STEP 5 into the gas state equation again, so that the volume V (1 ) Is calculated (STEP 6).

  Next, assuming that the sensor frame 31 itself is not deformed, the displacement calculation unit 20 does not change the cross-sectional area of the cavity 34, so the volume change (V (1) −V (0)) is calculated by the cross-sectional area of the cavity 34. By dividing, the displacement of the skin portion 33 is calculated (STEP 7). The displacement of the skin portion 33 obtained here is caused by a pressure wave transmitted to the arterial blood vessels near the skin portion 33. For this reason, it is possible to detect pressure pulse wave information by detecting the displacement of the skin portion 33.

  Then, the control unit 11 determines whether or not to continue the measurement (STEP 8). If it is determined that the measurement is to be continued (STEP 8; Y), the control unit 11 continuously causes the processing unit 14 to repeatedly execute the processing from step 2 and does not continue. If it is determined (STEP8; N), this process is terminated.

  In STEP 4, the air circulation mole number calculation unit 17 calculates the air inflow amount Q per unit time and the time interval (when the air inflow amount ΔN is calculated from the “reference table of differential pressure and air inflow amount” described above). T1-T0) is integrated. This step time can be set as needed.If the time is shortened, the amount of calculation increases, but a high-accuracy result can be obtained.If the length is shortened, the accuracy is reduced, but it can be calculated in a short time. Set.

  In addition, instead of the processing procedure of the flowchart shown in FIG. 6, the arithmetic processing unit 14 repeatedly acquires the piezoresistance value (STEP 2) for a predetermined time and stores the result data in the storage unit 13. Alternatively, the piezoresistance value may be sequentially read from the storage unit 13 and the processing after STEP3 may be performed. In addition, when the arithmetic processing unit 14 performs the acquisition of the piezoresistance value (STEP 2) and determines that the state in which the acquired piezoresistance value is less than the predetermined value continues for a predetermined time, the determination time point May be time T0 representing the initial state, and processing after STEP1 may be executed.

  As described above, the pressure pulse wave measurement unit 10 can detect pressure pulse wave information from the pressure wave of the arterial blood vessel by capturing a slight displacement of the skin portion 33 of the arterial blood vessel. Specifically, the displacement of the skin portion 33 is obtained by solving the equation of state of the gas obtained as a piezoresistance value generated from the bending of the cantilever 32 and taking into account the inflow and outflow of air between the outside air and the cavity 34. This displacement can be used as pressure pulse wave information. In addition, the pressure pulse wave measuring unit 10 can detect a high sensitivity that is greatly bent even with a slight differential pressure by using the cantilever 32 having only one end fixed. The pressure pulse wave measuring unit 10 can be interposed between the cantilever 32 and the sensor frame 31. By calculating the displacement of the skin portion 33 with high accuracy while taking into account the influence of air flowing in and out, highly sensitive and accurate detection of pressure pulse wave information can be realized.

(Detecting pressure pulse wave information when atmospheric pressure changes)
The above-described pressure pulse wave information calculation flow has been described when the atmospheric pressure is constant, that is, when there is no pressure fluctuation of the atmospheric pressure. However, when the pulse wave measuring apparatus 1 according to the present embodiment is actually used, the atmospheric pressure does not always change. The pressure pulse wave information calculation flow is a calculation process for finally obtaining pressure pulse wave information from the differential pressure between the atmospheric pressure Pout and the atmospheric pressure Pin in the cavity. The pressure pulse wave information obtained by the flow is added with the fluctuation of the atmospheric pressure Pout.

  An example is shown in FIG. FIG. 8A shows pressure pulse wave information calculated in a state where the atmospheric pressure fluctuates. In the period A, since the atmospheric pressure fluctuated, the pressure pulse wave information is a waveform having two peaks in one pulse wave unlike the previous and subsequent waveforms. If the determination is made based on the pressure pulse wave information deformed by such atmospheric pressure fluctuation, an abnormality determination such as a sudden rise in the pulse rate is made.

Therefore, a method of detecting accurate pressure pulse wave information using the verification pulse wave information obtained from the pulse wave verification unit 50 even when the atmospheric pressure Pout varies will be described with reference to FIGS. .
First, when the pulse wave measuring device 1 is worn, in a quiet environment and in a resting state, the pressure pulse wave measurement unit 10 provides pressure pulse wave information, and the pulse wave verification unit 50 provides verification pulse wave information as electrocardiographic information for a predetermined time. Measure (see FIG. 9). Here, it is desirable to measure a plurality of periods of pressure pulse wave information and electrocardiographic information having similar waveforms for each period.

  Next, the obtained electrocardiogram information is transmitted to the pressure pulse wave measurement unit 10 by the communication unit 57 in the pulse wave verification unit 50. The received electrocardiogram information is processed by the determination unit 70 provided in the pressure pulse wave measurement unit 10 in the same manner as the detected pressure pulse wave information. First, normal pressure pulse wave information and electrocardiogram information are compared, and synchronization processing is performed. Since the electrocardiogram waveform is a potential representing the contraction of the myocardium, and the pressure pulse wave information is information on the pressure wave transmitted to the pressure pulse wave measurement unit 10, a time difference C for transmitting the arterial blood vessel in the body is generated. In order to obtain the information of the time difference C, for example, the time of the maximum value of the electrocardiogram information and the time of the maximum value of the pressure pulse wave information at the nearest time after that time are obtained. The difference is obtained as a time difference C.

  Next, electrocardiogram information and pressure pulse wave information are acquired under the condition of the measurement target (see FIG. 8). From the obtained electrocardiogram information, heartbeat periods B1, B2, and B3 are obtained. Using the time difference C and the heartbeat periods B1, B2, and B3, the pulse periods b1, b2, and b3 of the pressure pulse wave information corresponding to the heartbeat periods B1, B2, and B3 of the electrocardiogram information are extracted. Each of the pulse periods b1, b2, and b3 of the pressure pulse wave information is compared with the normal pressure pulse wave information stored and stored in advance, and only the pressure pulse wave information of the normal pulse period is extracted. Here, only the pulsation period b3 is extracted and output from the determination unit 70 as normal pressure pulse wave information.

  Furthermore, cardiac function evaluation can also be performed using the pressure pulse wave information of the period b3. For example, the pulse rate is calculated on the basis of the pulsation cycle b3, integrating from the first time of the cycle b3 to the scar and from the minimum value to the last time of the cycle b3, and from the integrated value, the blood ejection ability of the heart is calculated. It is also possible to perform a process such as determining or calculating a ratio between the height of the maximum value of the pressure pulse wave information and the height of the scar to determine arterial vascular hardness or stress.

  Here, the known model waveform information is used for the determination of normal pressure pulse wave information. However, after acquiring the pressure pulse wave information of a plurality of pulsation periods and cutting out each pulsation period, An average value of two or more pieces of pressure pulse wave information that are very similar or coincident with each other may be determined as a normal waveform. Further, the time difference C may be obtained by measuring and averaging the time difference of the maximum value from a plurality of heartbeat cycles and pulsation cycles instead of once. The maximum value, minimum value, and trace time information of the pressure pulse wave information may be difficult to distinguish depending on the measurement situation, so the time value information of the maximum value can be obtained by differentiating the pressure pulse wave information. You can also.

  In addition, in the pressure pulse wave information or electrocardiogram information at rest before measurement, when there is a large variation for each cycle, it is necessary to obtain a time difference C by synchronizing one beat of the corresponding specific cycle. In this case, since it is not known how much time difference there is between the pressure pulse wave information and the electrocardiographic information to be synchronized, each period is cut out from both pieces of information, and one period and the heart of the pressure pulse wave information having a similar period One period of electric information is obtained, and a time difference C is obtained.

  Further, when the pulse rate becomes a very large value or a very small value due to arrhythmia, it may be determined that the cardiac function is abnormal without comparing with the pressure pulse wave information. Furthermore, if there are multiple peaks in the pressure pulse wave information during one heartbeat cycle of the electrocardiogram information, if it is not synchronized with the heartbeat cycle, or if flat pressure pulse wave information can be obtained, pressure pulse wave measurement It may be determined that there is an abnormality in the part 10 attachment method, and the measurement subject may be requested to attach again. Further, when the heartbeat information and the pressure pulse wave information cannot be synchronized within a certain period of time, an abnormality may be judged and the subject to be measured may be requested to review the attachment or maintain a rest.

  Since the pressure pulse wave measuring unit 10, particularly the differential pressure sensor 5, needs to be in close contact with the skin, if there is even a slight gap, the pressure wave is not transmitted and pressure pulse wave information synchronized with the pulse is obtained. Absent. For this reason, there should be a process for requesting the subject of measurement to review and redo the attachment.

  Further, a differential pressure sensor that is not intentionally brought into close contact with the skin and that does not detect pressure pulse wave information is separately provided, and an output signal of the differential pressure sensor and an output signal of the differential pressure sensor 5 that detects pressure pulse wave information are The difference signal can also be used as pressure pulse wave information. The differential pressure sensor provided with a gap detects not the pulse but the fluctuation of the atmospheric pressure. Therefore, by taking the difference from the output signal of the differential pressure sensor 5 that detects the pressure pulse wave information, the output corresponding to the fluctuation of the atmospheric pressure is output. The signal can be removed.

  Also, in electrocardiographic information, an electrode that is in close contact with the skin due to body movement or the like moves, and noise or myoelectricity due to body movement may be misrecognized as an electrocardiographic waveform, not a potential due to myocardial nerve transmission. For this reason, an inertial sensor such as an acceleration sensor is provided in the pulse wave verification unit 50 or the pressure pulse wave verification unit 10, and a rest determination is performed based on the output signal of the inertial sensor when the electrocardiogram information and the pressure pulse wave information are synchronized. May be. When the rest determination is negative, it is desirable to perform the process of performing synchronization again.

  In particular, since the pressure pulse wave information is likely to be superposed with extremely low frequency fluctuations caused by fluctuations in atmospheric pressure, it is desirable to extract the output via a high-pass filter having a frequency lower than the pulse frequency. As a result, the fluctuation of the atmospheric pressure is removed and at the same time the bias level is flattened, so that it is possible to easily determine the maximum value.

  In addition, although the structure which attaches the pressure pulse wave measurement part 10 to a wrist was shown here, you may install in the location where an artery exists in the body surface vicinity. For example, pressure pulse wave information can be obtained even if it is attached to the neck with the carotid artery, the inside of the elbow, the back of the knee, the base of the foot, the instep or the ankle, and it does not restrict the movement of the measurement subject. It is desirable to install.

  As described above, accurate pressure pulse wave information can be determined and detected even when atmospheric pressure varies. Furthermore, since judgment is performed only from normal pressure pulse wave information, it is possible to accurately determine cardiac function.

(Second Embodiment)
Next, the pulse wave measurement device 1 according to the second embodiment of the present invention will be described. Note that the same components as those in the first embodiment described above are denoted by the same reference numerals, and description thereof is omitted.
The difference from the pulse wave measuring apparatus 1 according to the first embodiment is that the pulse wave verification unit 50 is configured using a photoelectric pulse wave sensor instead of an electrocardiographic sensor.

  FIG. 10 shows the structure of the pulse wave verification unit 250 constituting the pulse wave measurement device according to this embodiment. The pulse wave verification unit 250 includes a photoelectric pulse wave sensor 253, a power source 54, a processing unit 55, a storage unit 56, and a communication unit 57.

  The photoelectric pulse wave sensor 253 includes a light source and a light receiving unit. The photoelectric pulse wave sensor 253 emits light from the light source toward the measurement subject, and the reflected light or transmitted light is received by the light receiving unit. This is a device for detecting volumetric pulse wave by detecting volume change of blood flowing through a light-irradiated blood vessel based on light intensity information of reflected light or transmitted light. The photoelectric pulse wave sensor 253 is generally mounted mainly on the fingertip or earlobe, but in recent years, it has been arranged on the back cover side of a wristwatch, and it has become possible to detect the pulse rate even on the wrist. Yes. In the description here, the main body 51 is fixed with the fingertip 233 sandwiched between clip-type springs.

Next, verification pulse wave information acquired by the pulse wave verification unit 250 will be described.
The photoelectric pulse wave sensor 253 detects and outputs a change in the volume of blood flowing through the blood vessel based on the intensity of reflected light or transmitted light of the irradiated light. Since the blood volume change is very similar to the pressure wave of the artery, the output signal of the photoelectric pulse wave sensor 253 has a waveform similar to the pressure pulse wave information.

Next, a method for obtaining normal pressure pulse wave information when the atmospheric pressure fluctuates will be described.
As in the first embodiment described above, volume pulse wave information that is verification pulse wave information using the pulse wave verification unit 250 and pressure pulse wave information using the pressure pulse wave measurement unit 10 when the measurement subject is at rest. To get. Next, using the maximum value or the minimum value of the volume pulse wave information and the pressure pulse wave information, each pulse wave information is cut out for each pulse period, and a time difference is obtained. Then, the pressure pulse wave information and volume pulse wave information in the measurement target situation are cut out for each pulse period, and only normal pressure pulse wave information is extracted as described above. Thereafter, processing such as predetermined pulse rate detection and cardiac function determination is performed.

  Further, as the verification pulse wave information, the acceleration pulse wave information obtained by second-order differentiation can be used instead of using the volume pulse wave information as it is. The acceleration pulse wave information can be used because it is easy to obtain a steep maximum value compared to the volume pulse wave information and easily distinguish between the maximum value and the maximum value as a heartbeat period.

  Instead of the photoelectric pulse wave sensor 253, a blood flow rate sensor may be used for the pulse wave verification unit 50. The flow velocity of blood flowing through a blood vessel is generally detected by irradiating an ultrasonic wave or a laser and utilizing the Doppler phenomenon of a reflected wave. For this reason, blood flow rate information can also be measured and used as verification pulse wave information.

  As described above, accurate pressure pulse wave information can be determined and detected even when atmospheric pressure varies. Furthermore, since the verification pulse wave information can be obtained optically, it is not necessary to contact the metal with the skin, and it can be used even by a measurement subject who has a metal allergy.

(Third embodiment)
Next, a processing flow of the pressure pulse wave measurement unit 10 according to the third embodiment of the present invention will be described with reference to FIG.

  FIG. 11 is a flowchart for explaining the displacement calculation processing of the skin portion 33 by the pressure pulse wave measurement unit 10 according to the third embodiment of the present invention. In addition, about the process same as 1st Embodiment, the same name is attached | subjected and description is abbreviate | omitted. Here, the displacement calculation process by the pressure pulse wave measurement unit 10 is different from the displacement calculation process in the first embodiment in that the pressure pulse wave information can be accurately measured even when the temperature fluctuates over time. .

  First, the arithmetic processing unit 14 acquires the air temperature K (0) using a temperature sensor connected to the pulse wave measuring unit 10 or provided in the apparatus main body 3 (STEP 11). In the initial state, the volume V (0) of the cavity 34 is determined by the design of the sensor frame 31, and the pressure Pin (0) in the cavity 34 is the same as the atmospheric pressure. The form is the same. Therefore, the air mole number calculation unit 18 calculates the mole number N (0) by substituting these V (0), Pin (0), and K (0) into the gas state equation (STEP 12).

  Thereafter, the steps from obtaining the piezoresistance value (STEP 13) to updating the number of moles (STEP 16) are the same as the displacement calculation process in the first embodiment.

  Next, the arithmetic processing unit 14 acquires the temperature K (1) at time T (1) (STEP 17). And the volume calculation part 19 calculates volume V (1) from the state equation of gas using the K (1) (STEP18). Subsequent processing is the same as in the first embodiment.

  In the pulse wave measurement unit 10 according to this embodiment, even when the air temperature fluctuates during measurement, the pressure wave is always accurate and highly sensitive by continuously measuring it and taking the temperature into account. Wave information can be measured.

(Fourth embodiment)
A pressure pulse wave measurement unit 10 according to a fourth embodiment of the present invention will be described with reference to FIG.
FIG. 12 is a flowchart for explaining the displacement calculation processing of the skin part 4 by the pressure pulse wave measurement unit 10 according to the fourth embodiment of the present invention. In addition, about the process same as 1st Embodiment, the same name is attached | subjected and description is abbreviate | omitted. Here, the displacement calculation process by the pressure pulse wave measurement unit 10 is different from the displacement calculation process in the first embodiment in that the pulse wave can be accurately measured even when the atmospheric pressure fluctuates greatly. It is.
First, the arithmetic processing unit 14 is connected to the pressure pulse wave measuring unit 10 or a pressure sensor capable of measuring an absolute pressure provided in the apparatus main body 3 or a cavity having substantially the same volume V (0) as the differential pressure sensor 5. A differential pressure sensor (not shown) having a pressure is separately installed to obtain atmospheric pressure (STEP 21).

  Since the pressure Pin (0) in the cavity 34 is the same as the atmospheric pressure in the initial state, the air mole number calculation unit 18 uses the atmospheric pressure measured in STEP 21 as Pin (0) and uses the mole number N (0 ) Is calculated (STEP 22).

  Next, the arithmetic processing unit 14 acquires a piezoresistance value from the differential pressure sensor 5 (STEP 23), and acquires the atmospheric pressure at time T (1) using a pressure sensor or a differential pressure sensor (STEP 24).

  Then, the arithmetic processing unit 14 updates the pressure in the cavity 34 from the atmospheric pressure acquired in STEP 24 and the differential pressure calculated based on the piezoresistance value acquired in STEP 23 to Pin (1). (STEP 25). Subsequent processing is the same as in the first embodiment.

  In the pressure pulse wave measurement unit 10 according to the present embodiment, even when the atmospheric pressure fluctuates greatly during measurement, the pressure pulse wave measurement unit 10 continuously measures the atmospheric pressure and performs processing in consideration of the fluctuation of the atmospheric pressure. This makes it possible to measure pressure pulse waves with accuracy and high sensitivity at all times.

(Fifth embodiment)
Next, a pressure pulse wave measurement unit 10 according to a fifth embodiment of the present invention will be described with reference to FIG.
FIG. 13 is a flowchart for explaining the displacement calculation processing of the skin portion 4 by the pressure pulse wave measurement unit 10 according to the fifth embodiment of the present invention. Here, the displacement calculation process performed by the pressure pulse wave measurement unit 10 is the same as that of the first embodiment, and the description thereof is omitted. Here, the displacement calculation process by the pressure pulse wave measurement unit 10 is different from the displacement calculation process in the first embodiment in that the pulse wave can be accurately measured even when the side wall of the cavity 34 is displaced in time. is there.

First, the arithmetic processing unit 14 acquires displacement information of the side wall of the cavity 34 (inner peripheral surface of the sensor frame 31) using a strain sensor (not shown) provided in the pressure pulse wave measurement unit 10 (STEP 31).
The air mole number calculation unit 18 calculates the volume V (0) of the cavity 34 by using both the displacement information and the design of the sensor frame 31, and based on this and the atmospheric pressure, the number of moles N in the cavity. (0) is obtained (STEP 32). The subsequent processing is the same as that of the first embodiment from the piezoresistance value acquisition (STEP 33) to the volume update (STEP 37).

  Next, the arithmetic processing unit 14 acquires displacement information at time T (1) by the strain sensor (STEP 38), and calculates the displacement amount of the skin surface using the latest cavity cross-sectional area (STEP 39). Subsequent processing is the same as in the first embodiment.

  In the present embodiment, even when the side wall of the cavity 34 changes during measurement, it is possible to always measure pressure pulse wave information accurately and with high sensitivity by measuring and processing it continuously.

  In the third embodiment, the fourth embodiment, and the fifth embodiment, the case where the temperature, the atmospheric pressure, and the side wall of the cavity 34 fluctuate was described. It is possible.

1 Pulse wave measuring device 1
2 Band 3 Device body 4 Skin 5 Differential pressure sensor 6 Aperture 7 Control board 10 Pressure pulse wave measurement unit 11 Control unit 12 Power source 13 Storage unit 14 Operation processing unit 15 Differential pressure calculation unit 16 Cavity internal pressure calculation unit 17 Air flow mole number Calculation unit 18 Molar number calculation unit 19 Volume calculation unit 20 Displacement calculation unit 31 Sensor frame 32 Cantilever 33 Skin part 34 Cavity 50 Pulse wave verification unit 51 Electrocardiogram detection unit 52 Belt 53 Electric sensor 54 Power supply 55 Processing unit 56 Storage unit 57 Communication unit 60 Communication unit 70 Judgment unit 233 Fingertip V Volume inside cavity 34 P Pressure inside cavity 34 N Number of moles of air inside cavity 34 STEP1-8 Each of the pulse wave measurement methods according to the first embodiment of the present invention Stages STEP 11 to 20 Each stage of the pulse wave measuring method according to the third embodiment of the present invention. Each stage of the fourth fifth measurement method of the pulse wave according to an embodiment of each stage STEP31~40 present invention method for measuring a pulse wave according to an embodiment of the TEP21~30 present invention

Claims (11)

A pulse wave measuring device that measures a pressure pulse wave that is a pressure wave transmitted through an arterial blood vessel,
The cavity has a cavity in which the bottom surface is released or a flexible film is fixed to the bottom surface, and the internal pressure and the atmospheric pressure of the cavity are large in a state where the bottom surface of the cavity is in contact with the skin. A differential pressure sensor that outputs a signal related to the differential pressure from the atmospheric pressure;
An arithmetic processing unit that calculates pressure pulse wave information based on the output of the differential pressure sensor;
A pulse wave verification unit that detects verification pulse wave information related to at least one of myocardial potential, volume pulse wave, and blood flow velocity;
A waveform synchronization processing unit to which the pressure pulse wave information and the verification pulse wave information are input;
With
The waveform synchronization processing unit
The pulse wave measuring device, wherein the verification pulse wave information is compared with the pressure pulse wave information, and the pressure pulse wave information is selected and output.   The waveform synchronization processing unit performs a synchronization process between the verification pulse wave information and the pressure pulse wave information after detecting a time difference between the verification pulse wave information and the pressure pulse wave information. 1. The pulse wave measuring device according to 1.   The waveform synchronization processing unit selects and outputs only the pressure pulse wave information similar to a normal waveform recorded in advance from the pressure pulse wave information subjected to the synchronization processing. Pulse wave measuring device.   The waveform synchronization processing unit is configured to obtain only the pressure pulse wave information similar to the waveform obtained by averaging the similar waveforms when a plurality of similar waveforms are obtained from the pressure pulse wave information subjected to the synchronization processing. The pulse wave measuring device according to claim 2, wherein the pulse wave measuring device is selected and output.   5. The pulse wave measuring apparatus according to claim 1, wherein a heart function is determined based on the pressure pulse wave information output from the waveform synchronization processing unit. The arithmetic processing unit includes:
When the skin pulsates, based on the output signal of the differential pressure sensor, a differential pressure calculation unit that calculates a differential pressure between the internal pressure and the atmospheric pressure of the cavity;
Based on the differential pressure calculated by the differential pressure calculation unit and the atmospheric pressure, a cavity internal pressure calculation unit that calculates the internal pressure of the cavity;
Based on the differential pressure calculated by the differential pressure calculation unit, an air flow mol number calculation unit that calculates the flow mol number of air flowing between the outside and the cavity;
Based on the flow mole number calculated by the air flow mole number calculation section, the air mole number calculation section for calculating the air mole number in the cavity;
Based on the number of air moles calculated by the air mole number calculation unit and the internal pressure of the cavity calculated by the cavity internal pressure calculation unit, a volume calculation unit that calculates the volume in the cavity;
The pulse wave measuring apparatus according to claim 1, further comprising: a displacement calculating unit that calculates a time displacement of the skin based on the volume in the cavity calculated by the volume calculating unit. The arithmetic processing unit has a circulation mole number database unit that stores in advance the circulation mole number of the air corresponding to the magnitude of the differential pressure,
7. The air flow mole number calculation unit extracts the air flow mole number corresponding to the magnitude of the differential pressure calculated by the differential pressure calculation unit from the flow mole number database unit. The pulse wave measuring device described in 1. The circulation mole number database unit obtains in advance a relationship between the pressure difference inside and outside the cavity and the amount of air flow by numerical calculation, and calculates the number of moles of air circulation based on the relationship and the differential pressure. The pulse wave measuring device according to claim 7, wherein the pulse wave measuring device is generated by calculation. An air temperature acquisition unit for acquiring temperature information of the air;
The pulse wave measurement according to any one of claims 6 to 8, wherein the air mole number calculation unit calculates the air mole number in the cavity based on the temperature information and the flow mole number. apparatus.   It has an atmospheric pressure acquisition part which acquires the atmospheric pressure, The pulse wave measuring device according to any one of claims 1 to 9 characterized by things. A strain detection unit that detects a displacement amount due to distortion of the side wall of the cavity;
The pulse wave measuring device according to any one of claims 6 to 10, wherein the volume calculation unit calculates a volume in the cavity using a displacement detected by the strain detection unit.

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