JP2017176340A - Electronic sphygmomanometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic sphygmomanometer capable of predicting a feasibility of future physical condition variation related to fatigue that is hard to acquire from single measurement of a blood pressure value and a fatigue degree.SOLUTION: The electronic sphygmomanometer: detects a biological signal of a measuring object person related to the circulatory organ; calculates a fluctuation degree of heartbeat intervals of the measuring object person from the detected biological signal; acquires a degree of cerebral fatigue of the measuring object person on the basis of the calculated fluctuation degree; calculates a difference between heart rates of the measuring object person in a recumbent position and a measuring position from the detected biological signal; acquires a degree of physical fatigue of the measuring object person on the basis of the calculated difference in the heart rates; pressurizes a cuff to detect a pressure inside the cuff and measures a blood pressure value of the measuring object person on the basis of a detection signal of the pressure in the cuff; determines a feasibility of the physical condition variation of the measuring object person on the basis of the measured blood pressure value, the degree of cerebral fatigue, and the degree of physical fatigue of the measuring object person; and outputs information for prompting awareness of the measuring object person related to the determined physical condition variation.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an electronic blood pressure monitor with a fatigue measurement function.

  In order to determine the subject's autonomic nerve and resting state, a sphygmomanometer is known that combines a blood pressure measurement function with an electrocardiogram detection function and a pulse detection function. For example, Patent Document 1 describes a blood pressure measurement system that includes a blood pressure measurement unit and an electrocardiogram monitoring unit, and determines whether to perform blood pressure measurement according to the measurement result of the autonomic nerve function obtained from the electrocardiogram. ing. In Patent Document 2, a pulse Doppler sensor mounted on a sphygmomanometer detects a subject's pulse and respiration in advance, and records a physical rest state and a mental rest state before blood pressure measurement and a blood pressure value. A sphygmomanometer is described.

  In addition, devices based on various measurement principles for determining the sleepiness, arousal level, and fatigue level of a measurement subject have been proposed. For example, Patent Document 3 describes a drowsiness determination device that determines the presence or absence of a subject's drowsiness from breathing intervals and heartbeat information. Patent Document 4 describes a wakefulness determination device that determines the presence or absence of a driver's sleepiness from the feature amount of heartbeat fluctuation. In Patent Literature 5, a driver's drowsiness level determined based on a driver's face image is used to determine the driver's drowsiness level using a database in which a road form, a drowsiness level current value, and a drowsiness level predicted value are associated with each other. A sleepiness prediction apparatus for predicting sleepiness is described.

  Fatigue is broadly divided into brain fatigue (central fatigue, mental fatigue) and physical fatigue (peripheral fatigue, muscle fatigue). Brain fatigue correlates with fluctuations in the interval between cardiac radio waves or pulse waves (beat interval). When there is no brain fatigue, there is fluctuation in the heart rate interval, but when there is brain fatigue, there is no fluctuation in the heart rate interval. For this reason, many apparatuses for determining the degree of brain fatigue of a person to be measured from information on cardiac radio waves or pulse waves have been proposed. For example, Patent Document 6 describes a diagnostic apparatus that digitizes a pulse wave waveform and / or an electrocardiographic waveform, creates a chaos attractor by mathematical operation from the discrete data, and calculates its Lyapunov exponent. In Patent Document 7, acceleration pulse wave data of a subject obtained by using a pulse meter or an electrocardiograph is analyzed by a maximum entropy method, and an LF value that is a low frequency component in a frequency domain and an HF value that is a high frequency component are obtained. A system is described that separates and determines a subject's fatigue based on LF / HF values obtained from those values.

  Physical fatigue is correlated with changes in heart rate and pulse rate, and heart rate is relatively low when there is no physical fatigue, but when there is physical fatigue, heart rate rises because a lot of blood is pumped into the muscles To do. For physical fatigue, measure your heart rate daily using a heart rate monitor to determine your average heart rate at rest. For example, the heart rate at the time of measurement is about 5-10 beats higher than that. There is a known method for determining fatigue. Also, for example, the heart rate is measured for 1 minute after 3 to 10 minutes have passed on its back, and then the heart rate is measured for 1 minute 15 seconds after standing up. There is also known a method of judging the degree of physical fatigue from the magnitude of the difference from the heart rate. This method is based on the principle that the heart rate in the supine state, where the muscles are least used, is the lowest, and the higher the physical fatigue level, the more the heart rate in standing position deviates from the heart rate in supine position. .

JP 2007-159774 A JP2012-157435A International Publication No. 2010/143535 JP 2008-161664 A JP 2013-0669152 A Japanese Patent Publication No. 06-009546 Japanese Patent No. 5491749

  For purposes such as grasping fatigue levels in daily life, grasping fatigue recovery status in the morning or at break, improving work efficiency of companies and health management, and using in occupational categories where fatigue causes serious consequences such as driving and brain work Therefore, there is a desire to know the degree of fatigue. In particular, for example, in the morning before starting work, you may want to know whether you should be careful about sleepiness and fatigue. It has been. However, the above-described conventional apparatus determines the sleepiness and fatigue level of the measurement subject at the time of measurement, and cannot predict the sleepiness and fatigue level of the measurement subject after the measurement. The drowsiness prediction device of Patent Document 5 predicts driver drowsiness from a database of past cases. However, in order to realize this device, past case data needs to be accumulated. It is not applicable to any use.

  Therefore, the present invention provides an electronic device with a fatigue level measurement function that provides both a blood pressure value and a fatigue level, and provides more detailed health guidance to the measured person than when measuring the blood pressure level or the fatigue level alone. An object is to provide a sphygmomanometer. It is another object of the present invention to provide an electronic sphygmomanometer that can predict the likelihood of future physical condition fluctuations related to fatigue that cannot be determined by single measurement of blood pressure value and fatigue level.

  A cuff, a pressurization unit that pressurizes the cuff, a first detection unit that detects pressure in the cuff, and a first measurement unit that measures a blood pressure value of the person to be measured based on a detection signal of the pressure in the cuff. In addition to the measurement of the blood pressure value, a second detection unit that detects a biological signal of the person to be measured related to the circulatory organ, a first correspondence relationship between the heartbeat interval fluctuation degree and the brain fatigue degree, and standing position when lying down A second correspondence relationship between a heart rate difference and physical fatigue level, and a third correspondence relationship between a blood pressure value, a brain fatigue level, a physical fatigue level, and a physical condition variation type related to fatigue; Calculating a degree of fluctuation of the heartbeat interval of the person to be measured from the biological signal, referring to the first correspondence relationship based on the calculated degree of fluctuation, and a second measuring unit for acquiring the degree of brain fatigue of the person to be measured; A heart rate difference between the patient's lying position and the measurement time is calculated from the biological signal, and the second difference is calculated based on the calculated heart rate difference. A third measuring unit that obtains the physical fatigue level of the person to be measured with reference to the correspondence relationship, and refers to the third correspondence relationship based on the measured blood pressure value, brain fatigue level, and physical fatigue level of the subject person. There is provided an electronic sphygmomanometer comprising: a determination unit that determines the ease of occurrence of a physical condition variation of the subject to be measured; and an output unit that outputs information for alerting the determined physical condition variation The

  In the above electronic sphygmomanometer, the determination unit preferably determines whether or not sleepiness is likely to occur in the measurement subject after measurement of the blood pressure value, the degree of brain fatigue, and the degree of physical fatigue as a change in physical condition.

  In the electronic sphygmomanometer, it is preferable that the second detection unit detects a biological signal before the pressurizing unit pressurizes the cuff.

  In the electronic sphygmomanometer, the second detection unit preferably has a pair of electrodes held by the measurement subject for detecting the measurement subject's cardiac radio wave as a biological signal.

  Alternatively, the second detection unit includes a microwave generator that irradiates the person to be measured with a microwave, a microwave receiver that receives a Doppler-shifted reflected wave from the person to be measured, and a biological signal from the reflected wave as a biological signal. It is preferable to have a detection circuit that detects the pulse wave of the measurer.

  According to the electronic sphygmomanometer, it is possible to predict the likelihood of future physical condition fluctuations related to fatigue that cannot be determined by single measurement of blood pressure value and fatigue level.

1 is a schematic diagram showing an external appearance of an electronic blood pressure monitor 1. FIG. It is a figure which shows the left view, right view, and usage pattern of the electronic blood pressure monitor. 1 is a block diagram of an electronic blood pressure monitor 1. FIG. It is explanatory drawing of the electrocardiogram waveform 40 detected by the detection part 14. FIG. It is a figure which shows the example of the fluctuation | variation of RR interval. It is a graph which shows the time change of the heart rate by standing motion. It is a figure which shows the relationship between a Borg scale and the judgment division of a fatigue degree. It is a graph which shows the relationship between the fluctuation degree of RR space | interval, and a brain fatigue degree. It is a graph which shows the relationship between the heart rate difference at the time of a prone position, and a physical fatigue degree. It is a figure which shows the relationship between a blood-pressure value, a fatigue degree, and sleepiness. It is a figure which shows the example of the warning message corresponding to the combination pattern of the blood-pressure value used for the determination of the determination part 19, a brain fatigue degree, and a physical fatigue degree, and it. It is a figure which shows the example of a display of a measurement result. It is a figure which shows the example of a display of a measurement result. 3 is a flowchart showing an operation example of an initial setting mode of the electronic sphygmomanometer 1; 4 is a flowchart illustrating an example of an operation in a measurement mode of the electronic sphygmomanometer 1. FIG. 6 is a block diagram of another detection unit 50. It is explanatory drawing of the pulse wave waveform detected by the detection part.

  Hereinafter, an electronic blood pressure monitor will be described in detail with reference to the drawings. However, it should be understood that the present invention is not limited to the drawings or the embodiments described below.

  FIG. 1 is a schematic diagram showing the external appearance of the electronic sphygmomanometer 1. The electronic sphygmomanometer 1 has a main body 10 and a cuff 60.

  The electronic sphygmomanometer 1 is a sphygmomanometer with a fatigue measurement function. Since there is a medical relationship between current sleepiness, future sleepiness, current blood pressure value, and fatigue level, as will be described later, by measuring both current blood pressure value and fatigue level, It is possible to predict the ease of fatigue and drowsiness in the future. Therefore, the electronic sphygmomanometer 1 uses the combination pattern of the measurement results of the current blood pressure value, brain fatigue level, and physical fatigue level to cause future physical condition changes such as the ease of sleepiness and the ease of fatigue of the measurement subject. Ease of use is determined, and a warning message regarding health attention is notified to the subject. According to the electronic sphygmomanometer 1, for example, when deciding whether to go to the hospital or deciding whether to leave the office, I want to know in advance my health condition regarding fatigue so as not to make a mistake in a serious situation Sometimes, it is possible to grasp the blood pressure value and the fatigue level, which are the basis of physical condition management, with a single device.

  The cuff 60 incorporates an air bag that stores air sent from the main body 10. This air bag is connected to the main body portion 10 through an air pipe 61. The air pipe 61 is a pipe for sending air from the main body 10 to the cuff 60. For example, the cuff 60 is wound around the upper arm portion of the measurement subject at the time of use, and is fixed to the upper arm portion by a surface fastener provided on the surface of the cuff 60.

  2A to 2C are a left side view, a right side view, and a usage pattern of the electronic sphygmomanometer 1, respectively. FIG. 3 is a block diagram of the electronic sphygmomanometer 1.

  The main body unit 10 includes a main power switch 11, an operation unit 12, a display unit 13, a detection unit 14, a storage unit 15, a control unit 16, and a blood pressure measurement unit 20. As shown in FIGS. 1 to 2C, the main body 10 is rectangular when viewed from the front, and has a size and thickness suitable for a person to hold with both hands. As an example, the main power switch 11 is provided on a side surface of the upper body portion 10 when viewed from the front. Although the electronic sphygmomanometer 1 is operated by a battery, the power source is not limited to the battery and may be an AC power source.

  The operation unit 12 includes a measurement button 12A, a setting button 12B, and a selection button 12C. In the illustrated example, the operation unit 12 is provided on the lower front side of the main body unit 10. The measurement button 12A is a button for instructing start / stop of measurement of the blood pressure value and the fatigue level. The setting button 12B is a button for inputting information necessary for the operation of the electronic sphygmomanometer 1, and is used, for example, to shift to an initial setting mode described later. The selection button 12C is a button used by the user to select an input item in the initial setting mode, for example, and includes a + button and a − button.

  The display unit 13 is an example of an output unit, and includes, for example, a liquid crystal display panel (LCD). The display unit 13 displays the blood pressure value being measured, the maximum blood pressure value, the minimum blood pressure value, the measurement results of the brain fatigue level and the physical fatigue level, a progress bar indicating the progress of the measurement, and various messages for prompting the user to perform the operation. Etc. are displayed.

  The detection unit 14 is a second detection unit that detects a measurement subject's biological signal related to the circulatory organ, and includes a pair of electrodes 14L and 14R for detecting cardiac radio waves as the biological signal. As shown in FIGS. 2A and 2B, the electrode 14 </ b> L is provided on the left side surface of the main body 10, and the electrode 14 </ b> R is provided on the right side surface of the main body 10. As shown in FIG. 2C, the measurement subject holds the main body 10 with both hands when measuring the degree of fatigue. The detection unit 14 continuously detects the heart wave of the measurement subject while the left hand 70L and the right hand 70R of the measurement subject are touching the electrodes 14L and 14R, respectively.

  The detection unit 14 also includes a cardiac radio wave detection circuit 14A that detects a cardiac radio wave of the measurement subject from the biological signals input from the electrodes 14L and 14R. Note that an A / D converter is disposed in front of or behind the cardiac radio wave detection circuit 14A, and an output signal from the cardiac radio wave detection circuit 14A is input to the control unit 16 as a digital signal.

4A and 4B are explanatory diagrams of the electrocardiographic waveform 40 detected by the detection unit 14. The peak indicated by the symbol R in the electrocardiogram waveform 40 in FIG. 4A corresponds to the R wave generated when blood is pumped from the left ventricle to the aorta. The time interval from one R wave peak (R point) to the next R wave peak (R point) is referred to as "RR interval (RRI)". FIG. 4B shows two consecutive R points R _n and R _{n + 1} and their RR interval d _n . The electronic sphygmomanometer 1 uses the RR interval as the heartbeat interval, and measures the degree of fatigue of the measurement subject based on the degree of fluctuation and the heart rate calculated from the RR interval.

  The storage unit 15 is a nonvolatile memory such as an EEP-ROM, and stores information necessary for the operation of the electronic sphygmomanometer 1. Although details will be described later, the storage unit 15 has a first correspondence relationship between the fluctuation rate of the heartbeat interval and the brain fatigue level, and a second correspondence relationship between the heart rate difference when standing and the physical fatigue level when standing. , And the third correspondence relationship among the blood pressure value, the brain fatigue level, the physical fatigue level, and the type of physical condition variation related to fatigue.

  The control unit 16 is configured as a microcomputer control circuit including a CPU, RAM, ROM, and the like, and controls the operation of the electronic sphygmomanometer 1. Although details will be described later, the control unit 16 includes a blood pressure measurement control unit 17, a fatigue level measurement unit 18, and a determination unit 19 as functional blocks realized by the CPU.

  The blood pressure measurement unit 20 includes a pressurizing pump 23, a drive circuit 24, a pressure sensor 25, a pressure detection circuit 26, an exhaust valve 27, and a drive circuit 28. The pressurizing pump 23, the pressure sensor 25 and the exhaust valve 27 are connected to the cuff 60 via the air pipe 61.

  The pressurizing pump 23 is an example of a pressurizing unit that pressurizes the cuff, and pressurizes the inside of the air bag of the cuff 60 by sending air into the cuff 60. The drive circuit 24 drives the pressurizing pump 23 based on the control signal given from the blood pressure measurement control unit 17.

  The pressure sensor 25 is an example of a first detection unit, detects a pressure (cuff pressure) in the cuff 60, generates a pressure detection signal, and outputs the pressure detection signal to the pressure detection circuit 26. The pressure in the cuff 60 is the pressure in the air bag of the cuff 60. The pressure detection circuit 26 converts the pressure detection signal acquired from the pressure sensor 25 into a frequency signal and outputs the frequency signal to the blood pressure measurement control unit 17. The pressure in the cuff 60 is calculated from this change in frequency.

  The exhaust valve 27 includes, for example, a rubber slow leak valve that gradually exhausts the air in the cuff 60 at a constant speed during blood pressure measurement, and an electromagnetic valve that forcibly exhausts the air in the cuff 60 when measurement is completed or stopped. Is done. The drive circuit 28 opens and closes the exhaust valve 27 based on a control signal given from the blood pressure measurement control unit 17.

  The blood pressure measurement control unit 17 is an example of a first measurement unit that measures a blood pressure value of the measurement subject based on a pressure detection signal in the cuff 60. When the start of blood pressure measurement is instructed via the measurement button 12A, the blood pressure measurement control unit 17 first pressurizes the cuff 60 until the pressure detected by the pressure sensor 25 reaches a predetermined upper limit pressure. Next, the drive circuit 24 is controlled. Then, the blood pressure measurement control unit 17 gives a control signal for controlling the opening and closing of the exhaust valve 27 to the drive circuit 28 after being pressurized by the pressurizing pump 23 until the cuff pressure reaches the pressurizing upper limit pressure. The cuff 60 is gradually decompressed by the exhaust valve 27. At this time, the blood pressure measurement control unit 17 uses, for example, an oscillometric method based on data such as a start pressure value of each pulse wave detected from a change in frequency of the frequency signal generated by the pressure detection circuit 26 and a measurement time thereof. Then, the maximum blood pressure value and the minimum blood pressure value of the measurement subject are measured, and the pulse is calculated.

  Next, the principle of measuring the degree of fatigue by the electronic sphygmomanometer 1 will be described. For brain fatigue analysis (measurement of brain fatigue), the electronic sphygmomanometer 1 uses the Chaos Lyapunov exponent method. The Chaos Lyapunov exponent method is a method in which time series data of RR intervals are regarded as orbits of a chaotic dynamical system, and the orbital divergence is evaluated by the Lyapunov exponent.

FIG. 5A and FIG. 5B are diagrams illustrating examples of fluctuations in the RR interval. FIG. 5A shows an example when there is no brain fatigue (when normal), and FIG. 5B shows an example when there is brain fatigue (when fatigued). In these figures, for each of a plurality of RR intervals extracted as time-series data from an electrocardiogram waveform, the size of the RR interval of interest is the x coordinate, and the size of the previous RR interval is the y coordinate. This is a plot and is called a Lorentz plot. The horizontal axis of each figure is the current RR interval d _n, and the vertical axis is the previous one 1 RR interval d _n-1, the unit is both milliseconds.

  As can be seen from a comparison between FIG. 5A and FIG. 5B, in FIG. 5A when there is no brain fatigue, the RR interval changes irregularly with time and fluctuates in a complicated manner. On the other hand, in FIG. 5B when there is brain fatigue, each point is concentrated in the same region, so there is almost no fluctuation in the RR interval, or the RR interval changes with regular fluctuation. ing. In each case of FIG. 5A and FIG. 5B, if the set of plotted points is regarded as a trajectory of the dynamic system, the dynamic system of FIG. The dynamic system (B) has no chaotic properties. It is known that the maximum Lyapunov exponent is an index indicating the orbital divergence of a dynamic system, and the maximum Lyapunov exponent is positive when it is a chaotic dynamic system, but is negative when it is not a chaotic dynamic system.

ここで、Ｍは時系列データの総サンプル時間、ｄは時系列データの時刻ｋと時刻ｋ−１のパターン間の距離（ローレンツプロットにおける２次元平面上の距離）である。λ_１＞０であることが観測されれば、周期性のないカオス状態であると言える。そこで、電子血圧計１は、ＲＲ間隔の時系列データからＷｏｌｆ法に従って最大リアプノフ指数λ_１を算出し、その符号および大きさを調べることによりＲＲ間隔の揺らぎ度を定量化して、脳疲労度を判定する。 Further, the maximum Lyapunov exponent λ ₁ is simply calculated by the following formula using the Wolf method (Alan Wolf, “DETERMINING LYAPUNOV EXPONENTS FROM A TIME SERIES”, Physica 16D (1985), pp. 285-317, North-Holland, Amsterdam). It is known that it can be calculated as follows.

Here, M is the total sample time of the time series data, and d is the distance (distance on the two-dimensional plane in the Lorentz plot) between the time k and time k-1 patterns of the time series data. If it is observed that λ ₁ > 0, it can be said that the chaotic state has no periodicity. Therefore, the electronic sphygmomanometer 1 calculates the maximum Lyapunov exponent λ ₁ from the time series data of the RR interval according to the Wolf method, and quantifies the degree of fluctuation of the RR interval by examining the sign and size thereof, thereby calculating the degree of brain fatigue. judge.

  The electronic sphygmomanometer 1 uses a standing position comparison method for physical fatigue analysis (measurement of physical fatigue level). The standing position comparison method is based on the difference between the heart rate measured when the subject is lying on the back and the heart rate measured when the subject is standing and the standing heart rate measured when the subject is standing. This is a method for estimating the degree of physical fatigue.

  FIG. 6 is a graph showing the time change of the heart rate due to the standing motion. The horizontal axis in FIG. 6 indicates the elapsed time t, and the unit is seconds. The vertical axis indicates the heart rate HR, and the unit is bpm (beats / minute). The graph of FIG. 6 is a graph in which a plurality of results obtained by measuring the time change of the heart rate when one person to be measured is in a state where the physical fatigue levels are different are plotted. A curve group indicated by reference numeral 41 is a heart rate at a normal time (when there is no physical fatigue), and a curve group indicated by reference numeral 42 is a heart rate at the time of fatigue (when there is physical fatigue). The subject was lying on his back when t = -5, got up at t = 0, and continued to stand at t> 0.

  As can be seen from the graph of FIG. 6, in the supine state (−5 ≦ t <0), there is no significant difference due to the degree of physical fatigue except when the physical condition is specially different such as when there is heat. On the other hand, the heart rate increases immediately after standing (0 <t <20), and when 30 seconds or more (t ≧ 30) have passed after standing, the heart rate at the time of fatigue indicated by reference numeral 42 rather than the normal heart rate indicated by reference numeral 41. Heart rate is higher, and there is a difference in heart rate depending on the degree of physical fatigue. Therefore, the electronic sphygmomanometer 1 stores, for example, the heart rate when the measured person is lying on the back in the storage unit 15 in advance, and the heart rate is measured after 30 seconds or more have elapsed since the measured person stands. Measure physical fatigue based on the difference in heart rate. Since the heart rate of 40 beats corresponds to about 30 seconds, the electronic sphygmomanometer 1 measures the RR interval for 40 beats, for example, and uses the last data to obtain the heart rate at the time when 30 seconds or more have passed since standing. Calculate the number.

  The electronic sphygmomanometer 1 quantifies both the brain fatigue level and the physical fatigue level by converting them into the same index called RPE (Rate of Perceived Exertion). RPE originally expresses how to get tired during exercise in 5 to 20 stages (6 to 20 depending on the literature), and since it was first devised by a person named Borg, it is also called a Borg scale. Brain fatigue based mainly on autonomic nervous system evaluation and physical fatigue based on sports medicine differ in evaluation scales and are difficult to compare as they are. For this reason, the electronic sphygmomanometer 1 unifies the numerical values of the brain fatigue level and the physical fatigue level obtained by the above method into the RPE according to the correlation function between the brain fatigue level and the physical fatigue level and the RPE value.

  FIG. 7 is a diagram showing a relationship between the Borg scale and the determination section of the fatigue level of the electronic sphygmomanometer 1. The electronic sphygmomanometer 1 unifies the index of fatigue level into RPE, and determines the fatigue level of the person to be measured in four categories according to the magnitude. For example, when the RPE is 7 or less, the electronic sphygmomanometer 1 is “rest” which means that there is no fatigue, and when it is 8 to 11, “normal” which means that it is in the normal range during activity, When it is ˜14, it is determined as “light fatigue” which means that it is slightly fatigued, and when it is 15 or more, it is determined as “fatigue” which means that it is in a complete fatigue state. This classification determination is an example, and the number of classifications may be 5 or more and 3 or less, and the correspondence between the RPE value and the classification may be appropriately determined.

FIG. 8 is a graph showing the relationship between the degree of fluctuation of the RR interval and the degree of brain fatigue. FIG. 9 is a graph showing the relationship between the difference in heart rate between standing and standing and the degree of physical fatigue. The horizontal axis of FIG. 8 is the RPE value shown in FIG. 7, and the vertical axis is the value of the maximum Lyapunov exponent λ ₁ for the time series data of the RR interval. The horizontal axis in FIG. 9 is the RPE value shown in FIG. 7, and the vertical axis is the difference ΔHR (bpm) between the standing heart rate and the lying heart rate. Each graph plots the data obtained by measuring the maximum Lyapunov exponent λ ₁ and the heart rate difference ΔHR for each of five subjects when each person has various fatigue levels. When the maximum Lyapunov exponent and heart rate difference are measured from the heart rate information, and the RPE at that time is determined and plotted, it can be seen that there is a correlation as shown in FIGS. Therefore, the electronic sphygmomanometer 1 refers to the data of these graphs, and from the measured values of the maximum Lyapunov exponent λ ₁ and the heart rate difference ΔHR, the RPE value that is an index of the brain fatigue level of the subject and physical fatigue An RPE value that is an index of the degree is acquired.

Based on the above principle, the storage unit 15 uses the maximum Lyapunov exponent λ ₁ and the RPE value relating to the time series data of the RR interval shown in FIG. 8 as the first correspondence relationship between the fluctuation rate of the heartbeat interval and the brain fatigue level. The data indicating the correspondence relationship is stored. In addition, as a second correspondence relationship between the heart rate difference when standing with respect to the standing position and the physical fatigue level, the storage unit 15 determines the heart rate difference and RPE value when standing with respect to the standing position shown in FIG. Is stored. In addition, the storage unit 15 stores the heart rate of each person in the supine position for one or a plurality of measurement subjects.

  The fatigue level measurement unit 18 includes an RR interval extraction unit 31, a fluctuation level calculation unit 32, a brain fatigue level acquisition unit 33, a heart rate calculation unit 34, and a physical fatigue level acquisition unit 35 as more detailed functional blocks. Hereinafter, these functional blocks will be described.

  The RR interval extraction unit 31 creates RR interval time-series data from the cardiac radio wave (biological signal) detected by the detection unit 14. At that time, the RR interval extraction unit 31 obtains a position where the maximum value is obtained for each region in the electrocardiogram waveform that exceeds a predetermined detection threshold with respect to the amplitude, and sets the time interval of each position to RR. Extract as an interval. Note that the detection threshold (sensitivity) of the cardiac radio wave (R wave) used by the RR interval extraction unit 31 may be adjustable by the user via the operation unit 12 in the initial setting mode.

The fluctuation degree calculation unit 32 is an example of a second measurement unit, and calculates the fluctuation degree of the heartbeat interval of the measurement subject from the electrocardiogram waveform detected by the detection unit 14. At that time, the fluctuation degree calculation unit 32 calculates the maximum Lyapunov exponent λ ₁ as fluctuation degree from the time series data of the RR interval (heart rate interval) extracted by the RR interval extraction unit 31 according to the Wolf method, for example.

The brain fatigue level acquisition unit 33 is an example of a second measurement unit, and is stored in the storage unit 15 based on the maximum Lyapunov exponent λ ₁ (the fluctuation rate of the heartbeat interval) calculated by the fluctuation level calculation unit 32. With reference to the correspondence relationship (first correspondence relationship) in FIG. 8, the brain fatigue level of the measurement subject is acquired. For example, from the fatigue level classification of FIG. 7 and the correspondence relationship of FIG. 8, the brain fatigue level acquisition unit 33 has a brain fatigue level (RPE) = 5 when λ ₁ = 1.3, and the classification is “rest”. It is determined that The brain fatigue level acquisition unit 33 determines that the brain fatigue level (RPE) = 19 when λ ₁ = −1.5, and that the classification is “fatigue”. If λ ₁ is smaller than −0.1 (see the arrow in FIG. 8), the brain fatigue level acquisition unit 33 has a brain fatigue level (RPE) of 12 or more, and the classification is “light fatigue” or “fatigue”. Judge that there is.

  The heart rate calculation unit 34 is an example of a third measurement unit, calculates time-series data of the heart rate of the measurement subject from the electrocardiographic waveform detected by the detection unit 14, and further, when the measurement subject is in the supine position And the difference in heart rate between the measurement time and the measurement time. At that time, for example, the heart rate calculation unit 34 divides the 40-beat RR interval data measured immediately after standing up and extracted by the RR interval extraction unit 31 into 8 blocks. An average heart rate is obtained from the interval, and is used as the heart rate at the time of measurement of the subject. Since the heartbeat of 40 beats corresponds to about 30 seconds, the calculated heart rate is the heart rate after 30 seconds from standing. Then, the heart rate calculation unit 34 uses the heart rate at the time of the measurement subject's position stored in the storage unit 15 and the heart rate at the time of the measurement of the measurement subject calculated as described above. The number difference ΔHR is calculated.

  The physical fatigue level acquisition unit 35 is an example of a third measurement unit, and is based on the heart rate difference ΔHR calculated by the heart rate calculation unit 34 and is stored in the storage unit 15 as shown in FIG. ), The physical fatigue level of the measurement subject represented by the common index with the brain fatigue level is acquired. For example, from the fatigue level classification of FIG. 7 and the correspondence relationship of FIG. 9, the physical fatigue level acquisition unit 35 has a physical fatigue level (RPE) = 10 when ΔHR = 5, and the classification is “normal”. judge. Further, the physical fatigue level acquisition unit 35 determines that the physical fatigue level (RPE) = 14 when ΔHR = 20, and the classification is “light fatigue”. If the ΔHR is greater than 12 (see the arrow in FIG. 9), the physical fatigue level acquisition unit 35 determines that the physical fatigue level (RPE) is equal to or greater than 12, and the category is “light fatigue” or “fatigue”. .

The heart rate calculation unit 34 calculates a heart rate difference ΔHR from the same electrocardiographic waveform used by the fluctuation degree calculation unit 32 to calculate the maximum Lyapunov exponent λ ₁ . That is, the electronic sphygmomanometer 1 can measure both the brain fatigue level and the physical fatigue level only by measuring the electrocardiographic waveform once.

  FIG. 10 is a diagram illustrating the relationship among blood pressure values, fatigue levels, and sleepiness. Factors that cause sleepiness include “fatigue”, “blood pressure”, and “sleep”.

  There is a close relationship between sleep and fatigue, and many research papers have been presented to estimate sleepiness by heart rate analysis that correlates with fatigue, using car driving as a model (for example, “Masato Yanagihira,“ Driving state estimation "Development of technology", PIONEER R & D, 2004, Vol.14, No.3, p.75-82 "," Takefumi Nishiura, "Development of simple evaluation method of arousal level by fluctuation analysis of brain wave and pulse wave", 2007 (See February 1st, Japan Ergonomics Society). Since the human body tries to enter the fatigue recovery mode when it is in a fatigued state, from the state where the heart rate has decreased from the state where the heart rate has increased due to fatigue, or the state where the maximum Lyapunov exponent of the fluctuation rate of the heartbeat interval is low Sleepiness occurs at an increased stage. There is a correlation between physical fatigue and normal heart rate, and maximum Lyapunov exponent of brain fatigue and heart rate interval fluctuation, so if current brain fatigue or physical fatigue is high, time There is a risk of sleepiness over time.

  On the other hand, some sleepiness is caused by hypotension or anemia. If the maximum blood pressure value continues below 100 mmHg, the blood circulation in the brain deteriorates, and sleepiness and fatigue are likely to occur. Hypotensive symptoms include constitutional instinctal hypotension, post-exercise hypotension that occurs when physical fatigue recovers immediately after intense exercise, and blood that collects in the digestive system after eating, resulting in loss of blood circulation. (Eg, “Aichi Pharmacists Association Homepage,“ 4. Low Blood Pressure ”, [online], [March 10, 2016 search], Internet <URL: https: // www .apha.jp / medicine_room / entry-3518.html> ”,“ EPARK Hospital, “Drowsiness (not enough)”, [online], [March 10, 2016 search], Internet <URL: http: / /fdoc.jp/docs/case/3.html>, “Akira Miura,“ Effect of water intake on hypotension after exercise ”, June 5, 2009, Descent Sports Science, Vol. 30, p. 98 ").

  Furthermore, sleep apnea is a factor of sleepiness due to lack of sleep. If you don't get enough sleep at night, your fatigue during the day will not be able to be recovered, and both your brain fatigue and physical fatigue will increase, often resulting in hypertension (for example, " Fukunaga Kosuke, “Survey Research on Potential Sleep Apnea Syndrome in Business Persons”, 2014 Daiwa Securities Research Results ”,“ Guidelines for Diagnosis and Treatment of Sleep Breathing Disorders in Cardiovascular Area JCS 2010 2012/11/28 Update ").

  Therefore, for example, if the blood pressure value, the brain fatigue level, and the physical fatigue level are measured in the morning, it is possible to determine the risk of sleepiness during the day after the measurement from the combination pattern of these measured values.

  The determination unit 19 is based on the blood pressure value of the person measured by the blood pressure measurement unit 20, the brain fatigue level measured by the brain fatigue level acquisition unit 33, and the physical fatigue level measured by the physical fatigue level acquisition unit 35. Thus, it is determined whether the subject's physical condition is likely to change. At that time, the determination unit 19 refers to a combination pattern of a blood pressure value, a brain fatigue level, and a physical fatigue level described below with reference to FIG. After measuring the degree, it is determined whether or not sleepiness is likely to occur in the measurement subject.

  FIG. 11 is a diagram illustrating an example of a combination pattern of a blood pressure value, a brain fatigue level, and a physical fatigue level used for determination by the determination unit 19 and a corresponding warning message. The memory | storage part 15 memorize | stores the combination pattern of FIG. 11 as a 3rd correspondence between a blood pressure value, a brain fatigue level, a physical fatigue level, and the type of the physical condition fluctuation | variation regarding fatigue.

(Pattern 1: Fatigue state)
When the maximum blood pressure value is 101 to 139 mmHg, the brain fatigue level is “light fatigue” to “fatigue”, and the physical fatigue level is “light fatigue” to “fatigue”, the determination unit 19 performs measurement. It is determined that the person is in a fatigue state. As described above, when the human body is in a state of brain fatigue or physical fatigue, the human body enters a resting state, and is subsequently attacked by strong sleepiness. Therefore, when the determination unit 19 determines that the measurement subject is in a fatigued state, the determination unit 19 causes the display unit 13 to display a warning message to that effect and to pay attention to sleepiness.

(Pattern 2: Hypotension)
When the maximum blood pressure value is 100 mmHg or less, the brain fatigue level is “rest” to “normal”, and the physical fatigue level is “rest” to “normal”, the determination unit 19 indicates that the subject is low Determined to have blood pressure. Hypotension is a state in which blood circulation is weak and the blood flow itself is low, and the body becomes deficient in oxygen, so that drowsiness, dizziness, and physical fatigue tend to occur thereafter. Therefore, when the determination unit 19 determines that the subject has hypotension, the determination unit 19 causes the display unit 13 to display a message to that effect and a warning message to urge attention to sleepiness and fatigue.

(Pattern 3: lack of sleep)
When the maximum blood pressure value is 140 mmHg or more, the brain fatigue level is “light fatigue” to “fatigue”, and the physical fatigue level is “light fatigue” to “fatigue”, the determination unit 19 Is determined to be lack of sleep. In this case, sufficient sleep rest cannot be obtained due to normal lack of sleep or sleep apnea, etc., and blood pressure rises and fatigue tends to accumulate. Therefore, when the determination unit 19 determines that the person to be measured is lacking sleep, the determination unit 19 causes the display unit 13 to display a warning message to that effect and to pay attention to sleepiness.

(Pattern 4: Chronic fatigue syndrome)
When the maximum blood pressure value is 100 mmHg or less, the brain fatigue level is “light fatigue” to “fatigue”, and the physical fatigue level is “rest” to “normal”, the determination unit 19 Determined to have chronic fatigue syndrome. Chronic Fatigue Syndrome (CFS) is an independent disease that differs from normal and chronic fatigue. Patients with chronic fatigue syndrome usually have abnormalities in the sympathetic and parasympathetic nervous systems, with symptoms such as tachycardia, decreased plasma volume, and decreased red blood cell volume. In addition, patients with chronic fatigue syndrome have standing intolerance and tend to faint easily. Therefore, when the determination unit 19 determines that the measurement subject has chronic fatigue syndrome, the determination unit 19 causes the display unit 13 to display a warning message to that effect and to pay attention to fainting.

(Pattern 5: Mental stress hypertension)
When the maximum blood pressure value is 140 mmHg or more, the brain fatigue level is “light fatigue” to “fatigue”, and the physical fatigue level is “rest” to “normal”, the determination unit 19 Judged as having mental stress hypertension. Mental stress hypertension is hypertension that occurs because autonomic nerves are disturbed due to mental stress (brain fatigue), and is likely to occur in specific situations such as at work and hospitals (so-called workplace hypertension, white coat hypertension). Therefore, when the determination unit 19 determines that the subject has mental stress hypertension, the determination unit 19 causes the display unit 13 to display a warning message prompting attention to that effect and tension or anxiety.

(Pattern 6: Physical stress hypertension)
When the maximum blood pressure value is 140 mmHg or more, the brain fatigue level is “rest” to “normal”, and the physical fatigue level is “light fatigue” to “fatigue”, the determination unit 19 Determined as physical stress hypertension. Physical stress hypertension is caused by excessive blood pressure such as overtraining, and is caused by an increase in blood pressure to repair a state of physical fatigue. Therefore, when the determination unit 19 determines that the measurement subject has physical stress hypertension, the determination unit 19 causes the display unit 13 to display a warning message for prompting attention to that effect and excessive exercise.

  12A to 13B are diagrams illustrating display examples of measurement results. For example, the display unit 13 includes a display area 13A for fatigue level measurement results, a display area 13B for blood pressure measurement results, and a display area 13C for warning messages. In the display area 13B, the maximum blood pressure value, the minimum blood pressure value, and the pulse value measured by the blood pressure measurement unit 20 are displayed. In the display area 13A, the brain fatigue level measured by the brain fatigue level acquisition unit 33 and the physical fatigue level measured by the physical fatigue level acquisition unit 35 are displayed. In the display area 13A, for example, an RPE value bar graph 13D indicating brain fatigue level and an RPE value bar graph 13E indicating physical fatigue level are alternately displayed, but unlike the illustrated example, You may display a physical fatigue degree simultaneously. A warning message corresponding to the determination result by the determination unit 19 is displayed in the display area 13C.

  FIG. 12A shows a display example when the maximum blood pressure value is 125 mmHg, the minimum blood pressure value is 83 mmHg, the pulse value is 65 beats / minute, the brain fatigue level is “light fatigue”, and the physical fatigue level is “fatigue”. Show. In this case, since it corresponds to the pattern 1 shown in FIG. 11, the determination unit 19 determines that the measurement subject is in a fatigued state. For this reason, a warning message “Being tired and paying attention to sleepiness” is displayed in the display area 13C.

  FIG. 12B shows a display example when the maximum blood pressure value is 90 mmHg, the minimum blood pressure value is 65 mmHg, the pulse value is 55 beats / minute, the brain fatigue level is “normal”, and the physical fatigue level is “normal”. . In this case, since it corresponds to the pattern 2 shown in FIG. 11, the determination unit 19 determines that the measurement subject has hypotension. Therefore, a warning message “Low blood pressure, pay attention to sleepiness” is displayed in the display area 13C.

  FIG. 13A shows a display example when the maximum blood pressure value is 90 mmHg, the minimum blood pressure value is 68 mmHg, the pulse value is 65 beats / minute, the brain fatigue level is “light fatigue”, and the physical fatigue level is “normal”. Show. In this case, since it corresponds to the pattern 4 shown in FIG. 11, the determination unit 19 determines that the measurement subject has chronic fatigue syndrome. For this reason, a warning message “Caution on Chronic Fatigue Syndrome, Caution on Fainting” is displayed in the display area 13C.

  FIG. 13B shows a display example when the maximum blood pressure value is 163 mmHg, the minimum blood pressure value is 91 mmHg, the pulse value is 75 beats / minute, the brain fatigue level is “light fatigue”, and the physical fatigue level is “normal”. Show. In this case, since it corresponds to the pattern 5 shown in FIG. 11, the determination unit 19 determines that the measurement subject has mental stress hypertension. For this reason, a warning message “Warning about tension and anxiety” is displayed in the display area 13C.

  Note that the output method of the determination result by the determination unit 19 is not limited to display on the display unit 13, and other forms such as output of a voice message, alarm sound, and data output to an external device may be used.

  Below, the operation | movement flow of the electronic blood pressure monitor 1 is demonstrated. The operation flow shown in FIGS. 14 and 15 is executed by the CPU of the control unit 16 in accordance with a program recorded in advance in the ROM of the control unit 16.

  FIG. 14 is a flowchart illustrating an operation example of the initial setting mode of the electronic sphygmomanometer 1. The initial setting mode is a mode for storing the heart rate of the measurement subject in the supine position in the storage unit 15 for the measurement of the degree of physical fatigue. The heart rate in the supine position is accurate if the person to be measured is measured every time the electronic sphygmomanometer 1 is used, but the process shown in FIG. 14 may be performed at least once when the electronic sphygmomanometer 1 is used, for example. For example, when the measurement subject (user) presses the setting button 12B, the flow of FIG. 14 starts.

  First, the control unit 16 receives an input of a detection threshold value of a cardiac radio wave (R wave) used by the RR interval extraction unit 31 (step S11). At that time, the user (the person to be measured) selects an input value with the selection button 12C and presses the setting button 12B to determine.

  And the control part 16 receives selection of the input method of the heart rate at the time of a depression (rest) (step S12). As this input method, the user of the electronic sphygmomanometer 1 can select either direct input or actual measurement on the back. Therefore, when the user knows his / her heart rate in the supine position and selects the direct input, the control unit 16 accepts the direct input of the heart rate in the supine position (step S13).

  On the other hand, when the user does not know his / her heart rate when he / she is lying and selects the actual measurement on his / her back, the control unit 16 measures the heart rate when he / she is lying (step S14). At that time, the heart rate is measured when the user is in a supine posture and presses the measurement button 12A to hold the electrodes 14L and 14R. Then, the control unit 16 causes the display unit 13 to display the supine heart rate input in step S13 or measured in step S14, and stores it in the storage unit 15 (step S15). This completes the operation of the initial setting mode of the electronic sphygmomanometer 1.

  FIG. 15 is a flowchart illustrating an operation example of the measurement mode of the electronic sphygmomanometer 1. When the measurement subject presses down the measurement button 12A and grips the electrodes 14L and 14R after the standing-up operation is completed, the flow of FIG. 15 starts.

  When the cardiac radio wave is detected, first, the RR interval extraction unit 31 detects the R wave (step S31). For example, if the R wave is detected twice within 4 seconds (Yes in step S31), the RR interval extraction unit 31 continuously measures the RR interval for 40 beats (about 30 seconds) and stores the data in the storage unit 15 (step S32). In particular, since the Chaos Lyapunov exponent method requires a power of 2 data, the RR interval extraction unit 31 measures an RR interval of 32 beats or more.

Subsequently, in steps S33 to S35, the brain fatigue level is measured. At that time, the fluctuation degree calculation unit 32 calculates the maximum Lyapunov exponent λ ₁ according to the Wolf method from the time series data of the RR interval stored in step S32 (step S33). Then, the brain fatigue level acquisition unit 33 refers to the correspondence relationship of FIG. 8 stored in the storage unit 15 and converts the value of the maximum Lyapunov exponent λ ₁ calculated in step S33 into an RPE value (step S34). ). Furthermore, the brain fatigue level acquisition unit 33 determines which fatigue level category the RPE value obtained in step S34 belongs to (step S35).

  Next, in steps S36 to S38, the physical fatigue level is measured. At that time, the heart rate calculation unit 34 calculates the heart rate at the time of measurement of the measured person from, for example, data for the last 10 beats among the time series data of the RR interval stored in step S32, A difference from the heart rate of the person being measured who is stored in advance in the storage unit 15 is calculated (step S36). Then, the physical fatigue level acquisition unit 35 refers to the correspondence relationship of FIG. 9 stored in the storage unit 15 and converts the heart rate difference calculated in step S36 into an RPE value (step S37). Furthermore, the physical fatigue level acquisition unit 35 determines which fatigue level category the RPE value obtained in step S37 belongs to (step S38).

  Next, in steps S39 to S43, blood pressure is measured. During blood pressure measurement, the blood pressure measurement control unit 17 pressurizes the cuff 60 with the pressurizing pump 23 until the pressure in the cuff 60 reaches the pressurization upper limit pressure (step S39). When the cuff pressure reaches the pressurization upper limit pressure, the blood pressure measurement control unit 17 controls the exhaust valve 27 to gradually exhaust the air in the air bag of the cuff 60 (performs a slow leak) (step S40). Then, the blood pressure measurement control unit 17 analyzes the pulse wave of the measurement subject based on the pressure detection signal from the pressure sensor 25 during the slow leak (step S41), and uses the oscillometric method to measure the maximum blood pressure of the measurement subject. The value and the minimum blood pressure value are measured, and the pulse is calculated (step S42). When these values are obtained, the blood pressure measurement control unit 17 controls the exhaust valve 27 to forcibly exhaust the air in the air bag of the cuff 60 (step S43).

  Thereafter, the determination unit 19 refers to the combination pattern of FIG. 11 stored in the storage unit 15, and obtains the blood pressure value measured in step S42, the brain fatigue level obtained in step S35, and the step S38. From the physical fatigue level, it is determined which of the patterns 1 to 6 corresponds to the person to be measured (step S44). And the determination part 19 displays the warning message according to determination by step S44 on the display part 13 (step S45). The operation in the measurement mode of the electronic sphygmomanometer 1 is thus completed.

  Since the cuff 60 is pressurized and the pulse is measured at the time of blood pressure measurement, it is considered that the blood pressure value and the fatigue level can be measured simultaneously. However, the electronic sphygmomanometer 1 uses the blood pressure value and the fatigue level (brain fatigue level and physical fatigue level). Measure) separately. This is because the blood pressure value can be measured with about 5 to 7 pulse waves, but about 30 to 40 pulse waves are necessary for measuring the fatigue level, and the period during which the cuff 60 is tightened is painful for the subject. This is because it is necessary to shorten the period as much as possible. For this reason, it is preferable not to measure a blood pressure value and a fatigue degree simultaneously.

  The electronic sphygmomanometer 1 measures the blood pressure value after measuring the degree of fatigue. This is because tightening of the cuff 60 may cause the patient to feel pain and increase the degree of brain fatigue, and the degree of fatigue may not be measured correctly after blood pressure measurement. Therefore, in the electronic sphygmomanometer 1, the measurement subject holds the electrodes 14 </ b> L and 14 </ b> R with both hands before blood pressure measurement. Therefore, the detection unit 14 detects the cardiac radio wave before the pressurizing pump 23 pressurizes the cuff 60.

  In the electronic sphygmomanometer 1, in order to measure the degree of fatigue, the measurement subject needs to hold the electrodes 14L and 14R for a certain period before blood pressure measurement. However, if a microwave Doppler sensor is mounted on the electronic sphygmomanometer 1, it is possible to detect a pulse wave in a non-contact manner with respect to the person to be measured and measure the degree of fatigue from the pulse wave. Therefore, hereinafter, another detection unit using a microwave Doppler sensor will be described.

  FIG. 16 is a block diagram of another detection unit 50. The detection unit 50 is an example of a second detection unit, and detects a pulse wave as a biological signal of the measurement subject in a non-contact manner. The detection unit 50 includes a microwave Doppler sensor 51, a respiratory component cut filter 52, a body motion detection circuit 53, and a pulse wave detection circuit 54.

  The microwave Doppler sensor 51 is a sensor that irradiates the object with microwaves and detects the movement of the object from the Doppler shift of the reflection. In particular, the microwave has a property of reflecting at a site where the skin and blood vessels are dense, and a signal synchronized with the pulse wave can be obtained from the movement of the body surface synchronized with the heart of the human chest and the blood movement of the aortic blood vessel. The microwave Doppler sensor 51 includes a microwave transmitter 51A, a microwave receiver 51B, and a microwave Doppler demodulator 51C.

  The microwave transmitter 51A irradiates the measurement subject with microwaves and outputs a transmission microwave signal, which is an electrical signal corresponding to the microwaves, to the microwave Doppler demodulator 51C. The microwave receiver 51B receives the Doppler-shifted reflected wave from the measurement subject and outputs a received microwave signal, which is an electrical signal corresponding to the received reflected wave, to the microwave Doppler demodulator 51C. The microwave Doppler demodulator 51C generates a phase difference signal between the transmission microwave signal and the reception microwave signal. Note that an A / D converter is disposed in the preceding stage or the subsequent stage of the microwave Doppler demodulator 51C, and an output signal from the microwave Doppler demodulator 51C is input to the respiratory component cut filter 52 as a digital signal.

  FIG. 17 is an explanatory diagram of a pulse wave waveform detected by the detection unit 50. In FIG. 17, the horizontal axis represents time T, and the vertical axis represents the amplitude of the output signal Do from the microwave Doppler sensor 51. The section A corresponds to a time region in which a relatively large body movement occurs when the measurement subject sits in front of the electronic sphygmomanometer 1 or wears the cuff 60 on the arm. The section A ′ corresponds to a point in time when the person to be measured stops body movement for measurement. The section B corresponds to a time region in which the measurement subject remains stationary and the measurement subject's heart is near the electronic sphygmomanometer 1. In the section A, the output signal Do reaches the upper limit Dx and the lower limit Dm repeatedly and is saturated due to relatively large body movement. However, the amplitude of the output signal Do attenuates at the section A ′ as indicated by the symbol Ds in response to the measurement subject's body motion being stopped. It falls within the amplitude range Dr.

  Therefore, it is possible to detect whether or not the measurement subject sits in front of the electronic sphygmomanometer 1 and can be measured based on whether or not the output signal Do has a periodic waveform as in the section B. And it is possible to detect a to-be-measured person's pulse wave from the waveform of the output signal Do of the area B. FIG.

  The respiratory component cut filter 52 is a filter that removes long-period waviness synchronized with respiration from the output signal of the microwave Doppler sensor 51. The body motion detection circuit 53 detects the presence or absence of a relatively large body motion from the frequency with which the output signal of the respiratory component cut filter 52 is saturated. That is, the body motion detection circuit 53 detects whether or not the output signal of the respiratory component cut filter 52 is saturated and the output signal has a periodic waveform like the waveform in the section B shown in FIG. The pulse wave detection circuit 54 is a detection circuit corresponding to the cardiac radio wave detection circuit 14 </ b> A of the detection unit 14, and when the body motion detection circuit 53 detects that the body motion of the measurement subject has stopped, the respiratory component cut filter 52. The pulse wave of the measurement subject is detected from the waveform of the output signal.

  If the chest of the measurement subject is within a range of about 20 cm from the microwave Doppler sensor 51, the detection unit 50 can detect a pulse wave signal synchronized with the heartbeat in a non-contact manner. Since the pulse wave is considered to have a one-to-one correspondence with the cardiac radio wave, if the detection unit 50 is used instead of the detection unit 14, the subject 14 holds the electrodes 14L and 14R for a predetermined time before blood pressure measurement. The heart rate interval and the heart rate are measured only by sitting in front of the electronic sphygmomanometer 1. For this reason, in the electronic sphygmomanometer 1 using the detection unit 50, it is possible to reduce the load on the measurement subject before blood pressure measurement, compared to the case where the detection unit 14 is used.

  Even when the detection unit 50 is used, it is preferable that the blood pressure measurement and the fatigue level measurement are performed separately because microwave irradiation may affect the control of blood pressure measurement. Even when the detection unit 50 is used, it is preferable to measure the fatigue level before blood pressure measurement because the tightening of the cuff 60 may affect the fatigue level.

  For the analysis of the fluctuation of the RR interval in the brain fatigue analysis, for example, the LF / HF method may be used in addition to the Chaos Lyapunov exponent method. The LF / HF method analyzes the frequency components of the RR interval time series, and calculates the LF / HF value by adding the spectrum power in the section of LF = 0.04 to 0.15 Hz and HF = 0.15 to 0.40 Hz. Then, the value is evaluated. There are three frequency analysis methods in the LF / HF method, for example, a fast Fourier transform (FFT) method, a maximum entropy method (MEM), and a CD (Complex Demodulation) method.

  The fast Fourier transform method is a method in which time series data is regarded as a composite wave of a trigonometric function and decomposed into frequency components. The Fast Fourier Transform method requires a larger amount of data than the Chaos Lyapunov exponent method, and requires a measurement time of 5 minutes or more, which is suitable for mounting on a PC. The maximum entropy method is a method of probabilistically obtaining a spectrum by creating simultaneous equations from an autoregressive model and autoregressive coefficients. The maximum entropy method can be executed with less data and a shorter measurement time (about 2 to 3 minutes) than the fast Fourier transform method, but is suitable for mounting on a PC because the processing is complicated and the calculation load is large. The CD method is a method of obtaining a spectrum from a generated modulation component by adding a predetermined frequency to a time series like a wireless heterodyne system. The CD method can be executed with a shorter measurement time of several seconds than the maximum entropy method, but the maximum entropy method is still more suitable for mounting on a PC because it requires a larger calculation load.

Further, the CVRR method may be used for the analysis of the fluctuation of the RR interval in the brain fatigue analysis. The CVRR method is a method for evaluating the degree of fluctuation of the RR interval by the following equation.
CVRR = (standard deviation of RR interval / average value of RR interval) × 100 (%)

  Even when the LF / HF method or the CVRR method is used, as in the case of the Chaos Lyapunov exponent method, the obtained index value can be converted into the RPE value to quantify the degree of brain fatigue. However, in the LF / HF method, since frequency decomposition is performed, a large number of data is necessary, and the measurement time becomes long. The CVRR method is a simple method, but has a problem that it is easily affected by fluctuations in the RR interval due to breathing or the like. On the other hand, since the chaotic Lyapunov exponent method does not require frequency resolution, it can be measured in a shorter time compared to the LF / HF method, and a more appropriate result can be obtained than the CD method or the CVRR method. Therefore, in practice, it is preferable to use the Chaos Lyapunov exponent method for brain fatigue analysis.

Further, in the physical fatigue analysis, the heart rate may be obtained from the heartbeat exercise intensity by the following equation according to the carbonnen method.
Exercise intensity = (Current heart rate-Resting heart rate) / (Maximum heart rate-Resting heart rate)
Maximum heart rate = 220−age However, in the case of the carbonnen method, the person to be measured needs to know the heart rate at rest. On the other hand, since the standing position comparison method can be executed by measuring the heart rate while lying on its back, even if the user does not know the heart rate at rest, it is easy to apply to a product. For this reason, in practice, it is preferable to use the standing position comparison method for physical fatigue analysis.

DESCRIPTION OF SYMBOLS 1 Electronic sphygmomanometer 10 Main body part 12 Operation part 13 Display part 14,50 Detection part 14A Cardiac wave detection circuit 15 Storage part 16 Control part 17 Blood pressure measurement control part 18 Fatigue degree measurement part 19 Judgment part 20 Blood pressure measurement part 23 Pressurization pump 24, 28 Drive circuit 25 Pressure sensor 26 Pressure detection circuit 27 Exhaust valve 31 RR interval extraction unit 32 Fluctuation degree calculation unit 33 Brain fatigue level acquisition unit 34 Heart rate calculation unit 35 Physical fatigue level acquisition unit 51 Microwave Doppler sensor 52 Respiratory component Cut filter 53 Body motion detection circuit 54 Pulse wave detection circuit 60 Cuff

Claims (5)

With cuff,
A pressurizing unit for pressurizing the cuff;
A first detector for detecting the pressure in the cuff;
A first measuring unit that measures a blood pressure value of the person to be measured based on a detection signal of the pressure in the cuff;
A second detection unit for detecting a measurement subject's biological signal related to the circulatory organ separately from the measurement of the blood pressure value;
First correspondence between heartbeat interval fluctuation and brain fatigue, second correspondence between heart rate difference and physical fatigue when standing, and blood pressure, brain fatigue and physical fatigue A storage unit for storing a third correspondence relationship between the degree of physical condition variation related to degree and fatigue;
A second measuring unit that calculates the degree of fluctuation of the heartbeat interval of the person to be measured from the biological signal and acquires the degree of brain fatigue of the person to be measured by referring to the first correspondence relationship based on the calculated degree of fluctuation; ,
A heart rate difference between the measurement subject's lying position and the measurement time is calculated from the biological signal, and the physical fatigue level of the measurement subject is obtained by referring to the second correspondence relationship based on the calculated heart rate difference A third measuring unit to
A determination unit that determines the ease of occurrence of physical condition fluctuation of the measurement subject with reference to the third correspondence relationship based on the measured blood pressure value, brain fatigue level, and physical fatigue level;
An output unit for outputting information for calling attention on the determined physical condition change;
An electronic blood pressure monitor characterized by comprising:   The electronic sphygmomanometer according to claim 1, wherein the determination unit determines whether drowsiness is likely to occur in the measurement subject after measurement of a blood pressure value, a brain fatigue level, and a physical fatigue level as the physical condition variation.   The electronic sphygmomanometer according to claim 1, wherein the second detection unit detects the biological signal before the pressurizing unit pressurizes the cuff.   The electronic sphygmomanometer according to claim 3, wherein the second detection unit has a pair of electrodes held by the measurement subject for detecting the measurement subject's cardiac radio wave as the biological signal. The second detector is
A microwave generator for irradiating the measurement subject with microwaves;
A microwave receiver for receiving a Doppler-shifted reflected wave from the subject;
A detection circuit for detecting a pulse wave of the measurement subject as the biological signal from the reflected wave;
The electronic sphygmomanometer according to claim 3, comprising:

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