JP4789203B2 - Blood pressure reflex function measuring device - Google Patents

Description

  The present invention relates to a technique for measuring a blood pressure reflex function, and more particularly to a technique for measuring a blood pressure reflex function that is an interaction between an autonomic nerve that governs a blood vessel and a blood vessel.

  The human body has a mechanism (autonomic nervous system) that keeps blood pressure constant, for example, when the blood pressure rises, the blood vessels are expanded to lower the blood pressure. However, for example, when the function of the autonomic nerves or blood vessels that control blood vessels is reduced, the blood vessels do not expand properly even if the blood pressure rises, resulting in symptoms of hypertension.

There are various causes of hypertension, and in the treatment, it is important to apply an appropriate drug according to the factor. For example, β-blockers act on the autonomic nervous system that governs the heart, reducing blood pressure by reducing heart rate and reducing contractile force. In addition, calcium antagonists act directly on blood vessels and lower blood pressure by dilating blood vessels.
Therefore, for hypertension caused by dysfunction of autonomic nerves that control blood vessels, administration of calcium antagonists instead of β-blockers leads to effective treatment.

  Conventionally, as a method of measuring autonomic nervous function (blood pressure reflex function) related to blood pressure fluctuation, a regression obtained from the relationship between blood pressure and heart rate by intravenously injecting drugs such as cardiovascular vasopressor and antihypertensive agents A method for measuring a blood pressure reflex function based on a straight line is known (Non-Patent Document 1).

  In addition, blood pressure reflex function is measured by forcibly changing the patient's position from the prone position to the standing position with the head-up tilt device while continuously measuring blood pressure while inserting a cannula into the patient's radial artery. A method is known (Non-Patent Document 2).

  Furthermore, a method has also been proposed in which blood pressure and heart rate are continuously measured with a Holter electrocardiogram or blood pressure monitor without using a drug, and the blood pressure reflex function is measured from a regression line obtained from the relationship between blood pressure and heart rate ( Non-patent document 3).

McGarry K, Laher M, Fitzgerald D, Horgan J, O'Brien E, O'Malley K., “Baroreflex function in elderly hypertensives”, Hypertension. 1983 Sep-Oct; 5 (5): 763-6. London GM, Levenson JA, Safar ME, Simon AC, Guerin AP, Payen D, “Hemodynamic effects of head-down tilt in normal subjects and sustained hypertensive patients”, Am J Physiol. 1983 Aug; 245 (2): H194-202 . Bigger JT Jr, La Rovere MT, Steinman RC, Fleiss JL, Rottman JN, Rolnitzky LM, Schwartz PJ, “Comparison of baroreflex sensitivity and heart period variability after myocardial infarction”, J Am Coll Cardiol. 1989 Nov 15; 14 (6) : 1511-8.

  However, since the method of Non-Patent Document 1 is an invasive method in which a drug is injected into a patient and a blood pressure fluctuation is artificially induced, the patient is burdened. Since the blood pressure reflex function is measured based on the relationship between blood pressure and heart rate, this method measures the functions of the autonomic nerves and blood vessels that control the heart, and the autonomous function that controls blood vessels. Nerve function cannot be measured. Since there is a local reaction in autonomic nerve control of a living body, the measurement result by the method of Non-Patent Document 1 cannot be used as the measurement result of the vascular blood pressure reflex function, which is a function of the autonomic nerve that controls blood vessels.

  Also, the method of Non-Patent Document 2 places a burden on the patient, similar to the method of Non-Patent Document 1. Furthermore, since a large-scale facility such as a head-up tilt device is required, there are problems of installation location and cost. Moreover, since the blood pressure reflex function is measured based on the relationship between the blood pressure and the heart rate as in the method of Non-Patent Document 1, the blood vessel blood pressure reflex function cannot be measured.

  The method of Non-Patent Document 3 is less burdensome on the patient than the methods of Non-Patent Documents 1 and 2, but also measures blood pressure reflex function based on the relationship between blood pressure and heart rate. The blood pressure reflex function cannot be measured (Non-patent Document 3).

  The present invention has been made in view of the above-described problems of the prior art, and provides a blood pressure reflex function measuring device capable of easily measuring the blood pressure reflex function non-invasively with a simple configuration. For the purpose.

  In order to achieve the above-described object, the blood pressure reflex function measuring device of the present invention includes a blood pressure acquisition unit that acquires time-series data of blood pressure measured during a predetermined period, and a pulse wave propagation time measured during the predetermined period. First, a plurality of sets of blood pressure and corresponding pulse wave propagation times are extracted using pulse wave propagation time obtaining means for obtaining time series data, time series data of blood pressure, and time series data of pulse wave propagation time. A first regression line is obtained using a plurality of combinations of one extraction means, blood pressure, and corresponding pulse wave propagation time, and the slope of the first regression line represents the degree of sensitivity of the vascular blood pressure reflex function. It has the 1st parameter | index calculation means calculated | required as a parameter | index, It is characterized by the above-mentioned.

  According to the present invention, it is possible to easily measure the vascular blood pressure reflex function non-invasively with a simple configuration.

Hereinafter, the present invention will be described in detail based on preferred embodiments with reference to the accompanying drawings.
● (first embodiment)
(Device configuration)
FIG. 1 is a block diagram illustrating a configuration example of a biological information measuring device as an example of a vascular blood pressure reflex function measuring device according to an embodiment of the present invention.

  The arithmetic control unit 10 controls the overall operation of the biological information measuring apparatus of this embodiment. The arithmetic control unit 10 is a general-purpose computer device having, for example, a CPU, ROM, RAM (including non-volatile RAM), and various interfaces (not shown), for example, a large-capacity storage device such as a built-in or external hard disk, an optical disk, or a ROM When the CPU executes the control program stored in, various operations described below are executed and controlled. Here, not all is processed by software, but at least a part thereof may be realized by hardware.

  The arithmetic control unit 10 also stores a display unit 70 that can display various operation guidance, measurement results, and diagnostic indicators, a recording unit 75 that can record and output measurement results and diagnostic indicators, a measurement result, and diagnostic indicators, for example, A storage unit 80 composed of a hard disk drive, a writable optical disk drive, a nonvolatile semiconductor memory, etc., a voice generation unit 85 capable of outputting voice guidance output and various notification sounds, a keyboard, a mouse, a button, a touch panel, etc. An input / instruction unit 90 that enables input and instruction is connected.

  In addition to this, a wired and / or wireless communication interface for communicating with other devices, a storage device using a removable medium, and the like may be provided. Further, the display unit 70 and the recording unit 75 may be separately connectable to the outside. That is, apart from the display unit 70 and the recording unit 75 built in the apparatus main body, an external display device having a larger display area and / or a larger display color, or an external recording device having a larger print area and / or a larger print color. Can be connected. Thereby, the miniaturization of the main body and the diversity of output can be realized at the same time. In this case, a known display interface and printer interface may be provided.

  The blood pressure measurement unit 205 measures blood pressure in the upper arm, fingertip, wrist, and the like. In the present embodiment, a pressure waveform (blood pressure waveform) at the fingertip is detected by a known volume compensation method. That is, using a sensor 25a composed of a photoelectric sensor in which a light emitting unit and a light receiving unit are located with a finger interposed therebetween and a cuff capable of pressing around the finger, a change in blood flow (volume) is detected by the photoelectric sensor. Adjust the cuff pressure to counteract the change. Thereby, the waveform of the cuff pressure is obtained as the blood pressure waveform. The blood pressure measurement in the blood pressure measurement unit 205 can be performed by any method that can be measured noninvasively.

  The electrocardiogram signal detection unit 204 detects an electrocardiogram signal from the electrodes 24a and 24b attached to the chest and limbs. In FIG. 1, two electrodes 24a and 24b are shown for convenience, but the actual number of electrodes can be changed according to the detected induction waveform.

The arithmetic control unit 10 obtains a pulse wave velocity (PTT) from the pressure waveform measured by the blood pressure measurement unit 205 and the electrocardiogram signal detected by the electrocardiogram signal detection unit 204. And the relationship between the blood pressure measured by the blood pressure measurement unit 205 and the pulse wave propagation velocity is recorded for each beat.
Then, a regression line obtained from the relationship between the blood pressure recorded over a predetermined period and the pulse wave velocity is obtained, and the slope is calculated as an index representing the degree of sensitivity of the vascular blood pressure reflex function.
The measurement process of the vascular blood pressure reflex function will be described in detail later.

  The heart sound detection unit 203 supplies a heart sound signal of the subject detected using the heart sound microphone 23 to the calculation control unit 10. The heart sound signal is mainly used to determine the start time of the pulse wave in the heart. The heart sound detection unit 203 and the heart sound microphone 23 are not essential for the biological information measuring apparatus of this embodiment.

The procedure and operation when measuring the vascular blood pressure reflex function using the biological information measuring apparatus having the above-described configuration will be described with reference to the flowchart shown in FIG.
The sensor 25a of the blood pressure measurement unit 205 is attached to the patient's finger, for example, the index finger. Further, electrodes 24a and 24b for measuring an electrocardiogram signal are attached to, for example, the chest of a patient.
Furthermore, in order to record the measurement data, the patient's personal information such as age, sex, height, and weight is input using the input / instruction unit 90.

  When preparation for measurement is completed and, for example, a measurement start instruction is given from the input / instruction unit 90, the arithmetic control unit 10 first sends a blood pressure measurement unit 205 and an electrocardiogram signal detection unit 204 (or heart sound detection unit 203). Instructs the start of the measurement process.

  In response to this, the blood pressure measurement unit 205 performs blood pressure measurement by the volume compensation method as described above, and outputs the cuff pressure to the arithmetic control unit 10 as a blood pressure measurement value. Further, the electrocardiogram signal detection unit 204 outputs the obtained electrocardiogram signal to the arithmetic control unit 10 (S101).

  The arithmetic control unit 10 uses the blood pressure measurement value (blood pressure waveform) and the electrocardiogram signal (electrocardiogram waveform) to determine the pulse wave propagation time (PTT) for each beat. Specifically, for example, the difference between the R wave occurrence time (peak time) in the electrocardiogram waveform and the time at the rising point of the corresponding blood pressure waveform is calculated as the pulse wave propagation time (S103).

  There is no limitation on the method for obtaining the time of the rising point of the blood pressure waveform, and any method can be used. For example, it can be obtained as the time at which the minimum value in the blood pressure waveform corresponding to one beat is obtained, the time at the rising point of the differential waveform of the blood pressure waveform, or the time of occurrence of a high frequency component in the blood pressure waveform.

  In S103, the arithmetic control unit 10 calculates a representative blood pressure (maximum blood pressure, minimum blood pressure, or pulse pressure) within one beat from the blood pressure waveform along with the calculation of the pulse wave propagation time. The arithmetic control unit 10 records the pulse wave propagation time obtained for each beat and the representative blood pressure in the storage unit 80 (S105).

  Note that the posture of the patient during the measurement period is not particularly limited, and may be a sitting position or a supine position. In addition, the patient may be in a state of resting during the measurement period, or some kind of stimulation that causes blood pressure fluctuations may be given to the patient. When giving a stimulus, for example, measurement may be performed while changing from a sitting position to a standing position, or measurement may be performed while forcibly changing the body position using a head-up tilt device. In addition to gravity-induced stimulations such as changes in body posture and posture, stimulations that affect emotions such as showing images or listening to sounds may be given.

  Although the measurement accuracy of the vascular blood pressure reflex function is expected to be improved by applying the stimulus to vary the blood pressure, the provision of the stimulus is not essential to the present invention. Even at rest, the representative blood pressure is not constant and varies to some extent, so that the vascular blood pressure reflex function can be measured.

The above measurement and recording process is continued for a predetermined measurement period (for example, several minutes). When the measurement period ends (S107, Y), the arithmetic control unit 10 converts the time series data of the pulse wave propagation time and the representative blood pressure recorded in the storage unit 80 during the measurement period into a format suitable for calculating the cross-correlation. Convert. Specifically, after interpolation by a method such as cubic spline interpolation, re-sampling is performed to generate an interpolation data series (S109).
Then, using the interpolation data series of pulse wave propagation time and the interpolation data series of representative blood pressure, the time difference (delay amount) at which the cross-correlation function becomes the maximum value is obtained (S111).

  Next, the arithmetic control unit 10 corrects the time axis by delaying one of the interpolation data sequence of the representative blood pressure or the interpolation data sequence of the pulse wave propagation time by the obtained delay amount, and the pulse wave propagation time corresponding to the representative blood pressure. A plurality of pairs are extracted. Here, as an example, it is assumed that the interpolated data series of the pulse wave propagation time is delayed (S113).

  Then, a regression line representing the relationship between the representative blood pressure and the corresponding pulse wave propagation time is obtained using the least square method or the like (S115). When the vascular blood pressure reflex function works well, when the blood pressure rises, the autonomic nerve that governs the blood vessels tries to dilate the blood vessels to lower the blood pressure. Since the expansion of the blood vessel is to relax the tension of the blood vessel wall, the pulse wave propagation time increases (the propagation speed decreases). That is, it is normal that blood pressure and pulse wave propagation time have a positive correlation.

  However, in a state where the vascular blood pressure reflex function is lowered, the correlation between the blood pressure and the pulse wave propagation time is lowered, and even if the blood pressure rises, the increase in the pulse wave propagation time is reduced or no increase is observed.

  Therefore, the degree of sensitivity of the vascular blood pressure reflex function can be evaluated by looking at the slope of the regression line as described above. When the calculation of the regression line is completed, the arithmetic control unit 10 sets parameters representing the regression line (for example, the values of a and b in the regression line y = ax + b) of the patient and the measurement date and time in the same manner as the measurement data. The information is recorded in the storage unit 80 in association with the information (S117).

  FIG. 3 is a diagram illustrating an example of an interpolation data sequence obtained by the arithmetic control unit 10, and FIG. 3A is a representative blood pressure, and FIG. 3B is an interpolation data sequence of pulse wave propagation time. In addition, in each interpolation data series, an interpolation series based on the measurement results in the sitting position and the supine position is shown.

  FIG. 4A shows the relationship between the cross-correlation coefficient of the interpolated data series based on the measurement result at the locus in FIG. 3 and the delay amount, and the delay amount d = about 2.3 seconds, that is, The maximum cross-correlation coefficient is obtained when the time axis of the interpolation data series of pulse wave propagation time is delayed by about 2.3 seconds.

  Calculated from the result of extracting a plurality of sets of representative blood pressure and corresponding pulse wave propagation time from the interpolation data series of representative blood pressure and the interpolation data series of pulse wave propagation time delayed by the delay amount d, and the relationship between them The regression line thus obtained is shown in FIG. FIG. 4B shows the relationship between the representative blood pressure and the corresponding pulse wave propagation time in the xy coordinate system in which the x axis represents the representative blood pressure BP (mmHg) and the y axis represents the pulse wave propagation time PTT (msec). While plotting, the regression line calculated | required by the least squares method is shown.

  In the example shown in FIG. 4B, the slope of the regression line is a positive value, indicating that the blood pressure and the pulse wave propagation time have a positive correlation. Therefore, it can be seen that the vascular blood pressure reflex function is functioning effectively. In addition, the greater the positive slope, the higher the degree of sensitivity of the vascular blood pressure reflex function.

  The arithmetic control unit 10 can output a two-dimensional graph as shown in FIG. 4B to the display unit 70 and / or the recording unit 75 as a measurement result of the vascular blood pressure reflex function. This output may be performed automatically after the measurement of the vascular blood pressure reflex function is completed, or may be performed in response to a user instruction from the input / instruction unit 90.

  When the vascular blood pressure reflex function is low or not functioning effectively, the slope of the regression line becomes small. In some cases, for example, as shown in FIG. 5A, a regression line having a negative slope is obtained. In patients with hypertension, when such a measurement result of vascular blood pressure reflex function is obtained, an appropriate antihypertensive agent acting on the autonomic nerve that governs blood vessels, such as calcium antagonists, is prescribed. Treatment can be performed. FIG. 5 (b) shows the results of measuring the vascular blood pressure reflex function again after administering a calcium antagonist for a predetermined period to the patient exhibiting the measurement results of FIG. 5 (a). .

  As is clear from the comparison between FIG. 5A and FIG. 5B, it can be seen that the vascular blood pressure reflex function is improved. The improvement of the vascular blood pressure reflex function is nothing other than the improvement of the function of suppressing an increase in blood pressure. Therefore, in the case shown in FIG. 5, the improvement of hypertension is realized by the administration of an appropriate drug.

(Modification 1)
In this embodiment, when the pulse wave propagation time (PTT) is obtained, the R wave generation time of the electrocardiogram is used. However, other information can also be used. For example, the generation time of the heart II sound can be used. In this case, instead of the electrodes 24a and 24b, the heart sound microphone 23 is attached to a predetermined chest position (second II intercostal sternum edge) of the patient. At the time of measurement, the heart sound detection unit 203 outputs the heart sound signal obtained by the heart sound microphone 23 to the calculation control unit 10, and the calculation control unit 10 obtains the generation time of the heart II sound from the heart sound waveform. By calculating the difference between this occurrence time and the rise time of the blood pressure waveform, the PTT for each beat can be determined.

(Modification 2)
Similarly, the blood pressure is not limited to the measurement with fingers by the volume compensation method, and both the measurement method and the measurement site can be changed. For example, measurement may be performed in the brachial artery or radial artery, and the tonometry method, volume pulse wave method, or the like may be used as the measurement method.

(Modification 3)
In the present embodiment, an example in which the present invention is applied to a biological information measuring device having a function of measuring representative blood pressure and pulse wave propagation time has been described. However, the measurement function is not essential, and it is possible to measure the vascular blood pressure reflex function by applying the processing after S109 in the flowchart of FIG. 2 to the already recorded representative blood pressure and pulse wave propagation time data. It is. In this case, the acquisition destination of the measured data is arbitrary, and may be, for example, the storage unit 80 or an external device connected to be communicable.

  As described above, according to the present embodiment, the vascular blood pressure reflex function can be measured based on the relationship between the blood pressure fluctuation and the accompanying pulse wave propagation time fluctuation. Both blood pressure and pulse wave propagation time can be measured non-invasively with a simple configuration, and the patient's load is small. Further, the present invention can be easily applied to a conventional apparatus capable of measuring blood pressure and pulse wave propagation time.

  By measuring the vascular blood pressure reflex function, it is possible to grasp whether or not the cause of hypertension is a decrease in the vascular blood pressure reflex function. Therefore, it is possible to appropriately select a drug used for treatment. In addition, the effect of drug administration can be easily confirmed by measuring the same patient before and after drug administration.

● (Second Embodiment)
In the first embodiment, the biological information measuring apparatus that performs only the measurement of the vascular blood pressure reflex function has been described. However, by measuring still another biological information about the blood vessel, a more comprehensive evaluation of the vascular blood pressure reflex function. Can be performed.
FIG. 6 is a block diagram showing a configuration example of the biological information measuring apparatus according to the second embodiment. The same reference numerals are given to the same configurations as those in the first embodiment, and the duplicate description will be omitted.

  The living body information measuring apparatus according to the present embodiment can measure blood pressure in the upper limb and the lower limb using a cuff, and can also measure a pulse wave velocity using an electrocardiogram signal and a pulse wave detected from the cuff. Information measuring device.

  That is, in the present embodiment, the arithmetic control unit 10 measures the systolic blood pressure Ps in the upper arm, ankle, and footpad from the pulse wave information obtained from the upper limb blood drive control unit 201 and the lower limb blood drive control unit 202. The upper limb lower limb blood pressure index can be obtained from the result. As the upper limb lower limb blood pressure index, ABI (ratio between right or left ankle systolic blood pressure and upper arm (representative) blood pressure) and TBI (ratio between right or left footpad systolic blood pressure and upper arm (representative) blood pressure) are obtained. it can. These have been used as indexes useful for diagnosing whether or not an artery is occluded. The arithmetic control unit 10 can also obtain the diastolic blood pressure Pd and the average blood pressure Pm.

  The arithmetic control unit 10 further detects a pulse wave signal supplied from the upper limb blood pressure control unit 201 and the lower limb blood pressure control unit 202 (if necessary, a heart sound signal or an electrocardiogram signal supplied from the heart sound detection unit 203 An electrocardiogram signal or the like supplied from the unit 204) and a blood vessel length between measurement sites (a blood vessel length equivalent value obtained in advance), and a heart (aortic valve mouth) -ankle or The pulse wave velocity (PWV) between the heart and the toes can be calculated.

  In addition, in this embodiment, the arithmetic control unit 10 can calculate biological information (referred to as a vascular elasticity index) representing vascular elasticity based on, for example, any one of the expressions 1 to 5 shown in FIG. Note that it is possible to arbitrarily determine whether the left side expression or the right side expression (the square root of the left side expression) is used among the expressions 1 to 5 in FIG. The vascular elasticity index is a useful index for diagnosing the degree of arteriosclerosis.

  The upper limb blood pressure control unit 201 and the lower limb blood pressure control unit 202 are respectively connected to two cuffs connected via the hoses 21h and 22h using a pump, an exhaust valve, or the like (not shown) according to the control of the arithmetic control unit 10. 21R, L, and 22R, L rubber sac (21aR, 21aL, 22aR, 22aL) is pressurized / depressurized (blood-driven). The upper limb blood pressure control unit 201 and the lower limb blood pressure control unit 202 are also provided with sensors for detecting pulse waves propagating through the hoses 21h and 22h, such as pressure sensors (211R, L and 221R, L). The pulse wave propagating through the rubber sac and the hose is converted into an electric signal and output to the arithmetic control unit 10. Although FIG. 6 shows a configuration in which the upper limb blood pressure control unit 201 and the lower limb blood pressure control unit 202 are independently provided, they may be integrated.

(Measurement process: Preparation before measurement)
A procedure and operation when performing measurement using the biological information measuring apparatus having such a configuration will be described. It is assumed that initial setting processing relating to device operation such as time setting is performed in advance. In addition, in the following, for ease of explanation and understanding, measurement using one upper limb and one lower limb of two pairs of cuffs will be described. Of course, measurement can be performed using all four cuffs. Is possible.

  First, as a preparation stage, a cuff, a sensor, and the like are attached to the subject. Specifically, the upper limb cuff 21R is attached to the subject's upper right arm and the lower limb cuff 22R is attached to the subject's ankle or toe. The cuff attached to the ankle and the cuff attached to the toe are different in configuration, but here both will be described as the lower limb cuff 22R. The cuffs 21 and 22 can be attached with a hook-and-loop fastener or the like.

  In addition, the heart sound microphone 23 is attached to a predetermined chest position of the subject (second II intercostal sternum edge) with a tape or the like.

  Next, the personal information of the age, sex, height, and weight subject is input using the input / instruction unit 90. Further, the blood vessel lengths to the II intercostal sternum margin and the cuff 21R and the cuff 22R attachment site are respectively measured by a scale or the like (or converted from the measured value) and input. This completes the preparation before measurement.

(Measurement processing: ABI measurement)
When preparation for measurement is completed and, for example, a measurement start instruction is given from the input / instruction unit 90, the arithmetic control unit 10 first starts blood pressure measurement processing to measure ABI. The order can be arbitrarily set, but first, the upper limb blood pressure control unit 201 is instructed to start pressurizing the upper right arm cuff 21R.

  The blood extremity control unit 201 for the upper limbs sends air to the cuff 21R to inflate the rubber sac 21aR. At the same time, a pulse wave propagates as a pressure wave of air from the rubber sac 21aR through the hose 21h and is detected by the pressure sensor 211R, and this pulse wave is converted into an electric signal (generally, the pressure sensor itself converts the pressure into electric pressure). Converted into a signal and output), and output to the arithmetic control unit 10 as a pulse wave signal obtained from the cuff 21R.

  The arithmetic control unit 10 causes air to be sent to the rubber sac 21aR by the upper limb blood pressure driving control unit 201 until no pulse wave is detected by the pressure sensor 211R, that is, until blood pressure is generated, and when the pulse wave is not detected. Stop pressurization. The cuff pressure at this time can be detected by the pressure sensor 211R. Then, the upper limb blood pressure control unit 201 is instructed to gradually decrease the cuff pressure.

  The upper limb blood-feeding control unit 201 adjusts an exhaust valve (not shown) to release air from the rubber sac 21aR, thereby reducing the cuff at a constant rate. In the process of decompression, the pulse wave begins to be detected again, and then contracts from the cuff pressure at the point where the pulse wave suddenly increases, the point where the maximum amplitude of the pulse wave is obtained, and the point where the pulse wave sharply decreases The systolic blood pressure Ps, the average blood pressure Pm, and the diastolic blood pressure Pd are obtained. The cuff pressure can be calculated using the value at the start of decompression, the decompression rate, and the decompression time. Such a blood pressure measurement method is known as an oscillometric method (volume pulse wave vibration method). When the diastolic blood pressure is obtained, the cuff is depressurized at once. Such blood pressure measurement processing is similarly performed on the remaining cuffs, and the blood pressure measurement of the upper limbs and the lower limbs is completed.

From the obtained blood pressure, the arithmetic control unit 10 obtains ABI as follows, for example.
ABI = right ankle systolic blood pressure / right upper arm blood pressure measured systolic blood pressure, mean blood pressure and diastolic blood pressure, and calculated ABI are stored in the storage unit 80, respectively.

(Measurement process: TBI measurement)
The lower limb measurement cuff 22R is attached to the toes (for example, the right toe), and TBI is measured and calculated in the same manner as ABI. The calculated TBI is stored in the storage unit 80.

(Measurement processing: PWV measurement)
Next, the process moves to the PWV measurement process. At the time of PWV measurement, the arithmetic control unit 10 controls the cuffs 21R and 22R to a pressure suitable for pulse wave detection, and acquires the brachial pulse wave and the ankle (or footpad) pulse wave. Further, the generation of a heart sound (for example, II sound) corresponding to the rising of the pulse wave is detected from the heart sound signal acquired via the heart sound detection unit 203. The pulse wave and the heart sound signal are each subjected to appropriate processing such as A / D conversion and stored in the storage unit 80. And PWV is calculated | required as follows.
PWV = AF / (t + tc)
here,
AF: Blood vessel length from the second intercostal sternum edge to the cuff 22R attachment site (ankle or toe) t: Time difference from the rise of the brachial pulse wave to the rise of the ankle (or toe) pulse wave tc: Heart sound II It is the time difference from the rise of the sound to the notch point of the brachial pulse wave.

  When the PWV measurement is completed, the arithmetic control unit 10 releases the cuff by the upper limb blood pressure control unit 201 and the lower limb blood pressure control unit 202, stores the measurement result in the storage unit 80, and ends the measurement process.

  As described above, the case where only the blood pressure and pulse wave measurement is performed on the upper right arm, the right ankle, and the right footpad has been described here, but the blood pressure and pulse are similarly applied to the left upper arm, the left ankle, and the left footpad. It is also possible to perform wave measurements. Also, PWV may be calculated for both the heart-ankle and the heart-toe, or may be calculated for each of the left and right sides.

(Calculation of vascular elasticity index)
Next, the arithmetic control unit 10 calculates a vascular elasticity index. As the vascular elasticity index, for example, values obtained by equations 1 to 5 shown in FIG. 7 can be used. In Expressions 1 to 5, k is a constant. Which formula is used to calculate the vascular elasticity index is determined in advance. Of course, it is possible to calculate two or more equations.

  The blood pressures Ps, Pm, and Pd used in Equations 1 to 5 are ideally the blood pressure at the center point of the section in which PWV is measured, but it is also possible to substitute, for example, the measurement value at the upper arm. . Note that the blood pressure at the center point can be estimated from, for example, a blood pressure measured at a site where a pulse wave is measured in order to calculate PWV, and this measurement value and a previously calculated conversion formula. Specifically, it is possible to estimate the blood pressure of a part existing between measurement points from the systematic body blood pressure distribution characteristic as shown in FIG. 8 and the values measured at two points of the part shown in this characteristic diagram. Is possible.

The estimation is performed using the fact that the systemic body blood pressure distribution characteristic linearly increases or decreases in both Ps and Pd from the aortic valve opening to the popliteal region, and Pm is almost constant in all sections. Specifically, for example, when estimating the systolic blood pressure Psi at the buttocks from the systolic blood pressure Ps at the ankle and the systolic blood pressure Psb at the upper arm,
(Ps-Psb): (distance of ankle-upper arm) = (Psi-Psb): (distance of buttock-upper arm)
Psi can be estimated from the relational expression. Similarly, Pdi can be estimated from Pd and Pdb.
The PWV used for calculating the vascular elasticity index may be the result of measurement using either the heart-ankle or the heart-footpad.

  The measured values of various biological information including blood pressure (systolic blood pressure Ps, diastolic blood pressure Pd, and average blood pressure Pm), and the calculated ABI, TBI, PWV, vascular elasticity index, etc. The information is stored in the storage unit 80 in association with the personal information and the measurement date / time. For example, a folder or directory is created for each subject, and each time measurement is performed, a folder or directory for each measurement is further created in the subject's folder or directory, and these biometric information and calculated parameters are acquired. Save waveform information etc.

Since (t + tc) obtained in the PWV measurement is the pulse wave propagation time, the PWV measurement process is continuously performed for a predetermined time, and the blood pressure measurement in the blood pressure measurement unit 205 is performed in parallel with the PWV measurement. Based on the correlation between the fluctuation and the fluctuation of the pulse wave propagation time, the measurement process of the vascular blood pressure reflex function described in the first embodiment can be performed. Of course, independently of the above-described PWV measurement process, blood pressure measurement and PWV measurement may be separately performed during the vascular blood pressure reflex function.
Needless to say, the pulse wave propagation time may be measured using the electrocardiogram signal by using the electrocardiogram signal detection unit 204 as in the first embodiment.

According to the present embodiment, in addition to the measurement of the vascular blood pressure reflex function, the vascular elasticity coefficient can be measured. Therefore, when there is a patient with a low vascular blood pressure reflex function, the blood vessel elasticity coefficient is evaluated together to evaluate the blood vessel It is possible to grasp whether the vascular contraction and dilatation due to the control of the autonomic nerve are slow due to the problem of the function of the autonomic nerve that governs the blood vessel or the fact that the blood vessel has hardened.
In addition, since information related to the presence or absence of blood vessel obstruction such as ABI or TBI is also obtained, comprehensive evaluation relating to vascular diseases becomes possible.

● (Third embodiment)
In the second embodiment, the biological information measuring device that measures biological information such as the vascular elasticity coefficient and ABI in addition to the vascular blood pressure reflection function has been described. In this embodiment, the blood pressure reflex function of the autonomic nervous system that controls the heart is further measured. By measuring the cardiac blood pressure reflex function, it is possible to evaluate a multifaceted blood pressure reflex function.

  As a method for measuring the cardiac blood pressure reflex function, for example, there is a method using a cross-correlation between blood pressure fluctuation and heart rate fluctuation. This is a method of using an instantaneous heart rate for each beat instead of the pulse wave propagation time for each beat in the first embodiment.

Specifically, instead of obtaining the pulse wave propagation time in S103 of FIG. 2, the instantaneous heart rate for each beat is obtained from the electrocardiogram signal, and in the subsequent processing, instead of the measurement result of the pulse wave propagation time, Use instantaneous heart rate. The instantaneous heart rate can be obtained as, for example, instantaneous heart rate (times / min) = 60 / n, where the RR interval of the electrocardiogram signal is n (sec).
FIG. 3C shows a heart rate interpolation data sequence obtained by interpolating the instantaneous heart rate in the same manner as in the first embodiment.

  In the same manner as in the first embodiment, a delay amount that maximizes the cross-correlation coefficient between blood pressure fluctuations and heart rate fluctuations is obtained, and a heart rate interpolation data sequence and a blood pressure interpolation in which the time axis is shifted by the delay amount The heart rate corresponding to the representative blood pressure is obtained from the data series. Then, the obtained result is plotted on the xy coordinate system to obtain a regression line.

  FIG. 9 is a diagram showing measurement results of the cardiac blood pressure reflex function. As blood pressure rises, the autonomic nerves that control the heart try to lower the blood pressure by lowering the heart rate. Therefore, when the cardiac blood pressure reflex function is normal, the blood pressure and the heart rate have an inverse correlation. In the example of FIG. 9, since the slope of the regression line is negative, it can be evaluated that the cardiac blood pressure reflex function is functioning correctly. The magnitude of the negative slope indicates the degree of sensitivity of the reflection function.

  The arithmetic control unit 10 can output a two-dimensional graph as shown in FIG. 9 to the display unit 70 and / or the recording unit 75 as a measurement result of the cardiac blood pressure reflex function. This output may be performed automatically after the measurement of the vascular blood pressure reflex function is completed, or may be performed in response to a user instruction from the input / instruction unit 90. Further, the two-dimensional graph of FIG. 4B, which is the measurement result of the blood vessel blood pressure reflex function, and the two-dimensional graph shown in FIG. 9 may be arranged and output on the same screen or recording medium. it can.

(Modification 1)
In the present embodiment, the cardiac blood pressure reflex function was measured based on the relationship between blood pressure fluctuations and heart rate fluctuations. However, for example, stroke volume is also controlled according to blood pressure fluctuations by the autonomic nervous system that controls the heart, so even if the relationship between stroke volume fluctuations and blood pressure fluctuations is used, the cardiac blood pressure reflex function Can be measured.

  The stroke volume can be calculated by, for example, an ultrasonic cardiac tomography method, an ultrasonic Doppler blood flow measurement method, an admittance method, or the like, but is not limited thereto. It is possible to measure simultaneously with blood pressure by connecting a measuring device to the biological information measuring device of this embodiment according to the measuring method. Of course, also in this modification, the measurement function is not indispensable, and it is possible to use results measured by other devices.

As described above, according to the present embodiment, the blood pressure reflex function can be more comprehensively evaluated by measuring the cardiac blood pressure reflex function together with the vascular blood pressure reflex function. For example, when prescribing an antihypertensive agent, it is useful in determining whether it is appropriate to administer a drug that acts on the cardiac reflex function or a drug that acts on the vascular blood pressure reflex function.
Furthermore, as described in the second embodiment, it is possible to evaluate a multifaceted vascular disease by taking into consideration other indices such as the vascular elasticity index and the upper limb lower limb blood pressure index.

● (Fourth embodiment)
It is also possible to measure yet another indicator for blood pressure reflex function. For example, changes in blood pressure and heart rate based on emotional responses due to stimuli such as video are also considered useful indicators for evaluating blood pressure reflex function.

  Focusing on fluctuation components with a period of about 10 seconds (referred to as Mayer waves) that are clearly included in heart rate fluctuations, blood pressure fluctuations, etc., at rest, heart rate fluctuations and blood pressure fluctuations restricted to the Mayer wave band It has been proposed to use the maximum value ρmax of the cross-correlation coefficient as an index of the degree of sensitivity to emotional reaction.

In the present embodiment, in addition to the vascular blood pressure reflex function and the cardiac blood pressure reflex function described above, this ρmax is obtained.
Specifically, as in the third embodiment, the arithmetic control unit 10 performs low-frequency components (0...) On an interpolation data series obtained by re-sampling the interpolation curve of the instantaneous heart rate measured for each beat and the representative blood pressure. 04 to 0.15 Hz) are extracted and obtained as a blood pressure low frequency component and a heartbeat low frequency component.

And when the blood pressure low-frequency component and heartbeat low-frequency component are x (t) and y (t), respectively, normalized cross-correlation function (cross-correlation coefficient) for 60 seconds before and after that at a certain time for a total of 120 seconds ρxy (τ) is obtained as follows.

Further, based on the following formula, the maximum value of ρxy (τ) in the region of 0 ≦ τ [s] ≦ 10 is obtained as the maximum cross-correlation coefficient ρmax. Since the period of the Mayer wave is about 10 seconds, the upper limit of τ is set to 10 seconds in order to obtain fluctuation within one period.

  The low-frequency component extraction (filtering process), the cross-correlation function, and the ρmax calculation process can be performed by the arithmetic control unit 10 in software, and any living body according to the first to third embodiments described above. Also in the information processing apparatus, ρmax can be calculated.

Thus, ρmax is obtained as time series data in a region where τ [s] is positive. For example, when an emotional reaction is induced by an image, ρmax decreases because the correlation between blood pressure fluctuation and heart rate fluctuation is low. The magnitude of the degree of decrease represents the degree of sensitivity to the emotional reaction. Moreover, although ρmax increases as it becomes resting, the ease of the rise varies from individual to individual, and it has been reported that those who are prone to motion sickness are unlikely to rise.
It should be noted that ρmax can be similarly obtained for the pulse wave propagation time and blood pressure.
According to the present embodiment, it is possible to measure the degree of sensitivity to a patient's emotion, which helps a more comprehensive diagnosis of the blood pressure reflex function.

It is a block diagram showing an example of composition of a living body information measuring device as an example of a vascular blood pressure reflex function measuring device concerning a 1st embodiment of the present invention. It is a flowchart explaining the vascular blood pressure reflex function measurement process in the biological information measuring device concerning a 1st embodiment of the present invention. It is a figure which shows the example of the interpolation data series produced | generated in the biometric information measuring apparatus which concerns on embodiment of this invention. It is a figure explaining vascular blood pressure reflex function measurement processing in the living body information measuring device concerning a 1st embodiment of the present invention. It is a figure which shows the example of the measurement result of the vascular blood pressure reflex function in the biometric information measuring apparatus which concerns on the 1st Embodiment of this invention. It is a block diagram which shows the structural example of the biometric information measuring apparatus as an example of the vascular blood pressure reflex function measuring apparatus which concerns on the 2nd Embodiment of this invention. It is a figure which shows the example of the calculation formula of the vascular elasticity index which can be measured with the biological information measuring device which concerns on the 2nd Embodiment of this invention. It is a figure which shows the example of the systematic body blood pressure distribution characteristic used when the biological information measuring apparatus which concerns on the 2nd Embodiment of this invention estimates the blood pressure used when calculating | requiring a vascular elasticity index. It is a figure which shows the example of the measurement result of the cardiovascular reflex function which the biological information measuring device which concerns on the 3rd Embodiment of this invention can measure.

Claims (8)

Blood pressure acquisition means for acquiring time series data of blood pressure measured in a predetermined period;
Pulse wave propagation time acquisition means for acquiring time series data of pulse wave propagation time measured during the predetermined period;
First extraction means for extracting a plurality of sets of blood pressure and corresponding pulse wave propagation time using the time series data of the blood pressure and the time series data of the pulse wave propagation time;
A first regression line is obtained using a plurality of sets of the blood pressure and the corresponding pulse wave propagation time, and the slope of the first regression line is obtained as an index representing the degree of sensitivity of the vascular blood pressure reflex function. And a blood pressure reflex function measuring device.   The extraction unit corrects the time axis of the time series data of the representative blood pressure or the pulse wave propagation time so that the correlation between the fluctuation of the blood pressure and the fluctuation of the pulse wave propagation time becomes the highest, The blood pressure reflex function measuring device according to claim 1, wherein a plurality of sets of the blood pressure and the corresponding pulse wave propagation time are extracted based on subsequent time-series data.   The output means for outputting a two-dimensional graph including a plurality of sets of the blood pressure and the corresponding pulse wave propagation time, and the first regression line. 2. The blood pressure reflex function measuring device according to 2. Heart rate information acquisition means for acquiring time-series data of instantaneous heart rate or stroke volume measured in the predetermined period;
A plurality of pairs of blood pressure and corresponding instantaneous pulse rate or stroke volume are extracted using the blood pressure time-series data and the instantaneous heart rate or stroke volume time-series data; Extraction means;
A second regression line is obtained using a plurality of pairs of the blood pressure and the corresponding instantaneous heart rate or stroke volume, and the slope of the second regression line represents the degree of sensitivity of the cardiac blood pressure reflex function. The blood pressure reflex function measuring device according to any one of claims 1 to 3, further comprising a second index calculating unit that is obtained as an index. The output means is
A first two-dimensional graph including a plurality of sets of the blood pressure and the corresponding pulse wave propagation time, and the first regression line;
A second two-dimensional graph including a plurality of sets of the blood pressure and the corresponding instantaneous heart rate or stroke volume, and the second regression line;
5. The blood pressure reflex function measuring device according to claim 4, wherein the blood pressure reflex function measuring device outputs such that the comparison is possible.   The blood pressure reflex function measuring device according to any one of claims 1 to 5, further comprising upper limb lower limb blood pressure index acquisition means for acquiring an upper limb lower limb blood pressure index.   The blood pressure reflex function measuring device according to any one of claims 1 to 6, further comprising a vascular elasticity index acquisition means for acquiring a vascular elasticity index. further,
Heart rate information acquisition means for acquiring time-series data of instantaneous heart rate or stroke volume measured in the predetermined period;
Filter means for extracting the low frequency component of the time series data of the blood pressure and the time series data of the instantaneous heart rate or stroke volume, and outputting as a blood pressure low frequency component and a heart rate low frequency component;
3. A third index calculating means for obtaining a maximum value of normalized cross-correlation coefficients of the blood pressure low-frequency component and the heartbeat low-frequency component as an index of the degree of sensitivity to emotional reaction. The blood pressure reflex function measuring apparatus according to claim 7.