JP5552982B2 - Pulse pressure measuring device and pulse pressure measuring method - Google Patents

Description

  The present invention relates to a fluid pressure measurement device, a fluid pressure measurement method, a blood pressure measurement device, and a blood pressure measurement method.

  It is very useful to measure the pressure of a fluid flowing in a certain conduit non-invasively, that is, without leaving a physical trace such as damage to the measurement target because the measurement target can be measured without load. Particularly in the living body, recently, attempts have been made to measure the fluid pressure in blood vessels, that is, blood pressure in a non-invasive and non-loading manner. For example, as a method for measuring blood pressure non-invasively and without load on a living body, a method using ultrasonic waves has been proposed. Obtain the maximum diameter and the minimum diameter in the local part of the artery, give the parameter values to the nonlinear function, and convert the diameter of each time input by the nonlinear function, so that The pressure is calculated (for example, see Patent Document 1).

  Further, a method has been proposed in which blood flow velocity, flow rate, volume, or the like is detected by ultrasonic waves and pulse wave velocity is detected by light waves, and the blood pressure and the amount of change thereof are calculated by associating both of these amounts (for example, Patent Literature 2 and 3).

Japanese Patent Laid-Open No. 2004-041382 JP-A-4-250135 JP 2004-154231 A

  However, as disclosed in Patent Documents 1 to 3, the calculation of blood pressure values using conventional ultrasonic waves requires calibration with a cuff type sphygmomanometer. This is a 24 hour free action, considering blood pressure measurement (24hABPM) and continuous blood pressure measurement every beat, there are inconveniences such as wearing a cuff all the time or carrying it around and use it regularly. Therefore, there is a possibility that the practical use becomes difficult.

  Moreover, in addition to the need for calibration with a cuff type sphygmomanometer, there is a possibility that the calibration is required regularly (about 30 minutes to 1 hour). In Patent Document 3, a correction coefficient including blood viscosity is obtained by a cuff sphygmomanometer, and blood pressure is derived using the correction coefficient. The blood viscosity varies depending on the amount of red blood cells, plasma viscosity, and red blood cell aggregation phenomenon. The aggregation phenomenon of erythrocytes can occur within a few hours by eating foods rich in lipids, and the change in blood viscosity accompanying this changes in the correction coefficient. That is, in order to obtain a correct blood pressure value continuously and continuously, it is not necessary to perform calibration once, but it is necessary to perform it at a certain interval, for example, about every hour.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  [Application Example 1] A fluid pressure measurement device including at least two measurement units that are spaced apart from each other along the longitudinal direction of the conduit of the measurement target unit, and a control unit that controls the measurement unit, The measurement unit includes a measurement medium transmission / reception unit that transmits a measurement medium to the measurement target unit, and acquires a part of the measurement medium returned from the measurement target unit, and the control unit includes one and the other of the measurement medium. The measurement unit measures the velocity of the fluid flowing in the conduit existing in the measurement target unit and the conduit diameter, the amount of change in the conduit diameter measured in the at least one measurement unit, the one measurement unit, and the one measurement unit Obtaining the amount of change in fluid pressure derived based on the difference in conduit diameter at the other measurement unit and the head difference derived based on the distance between the two measurement units, the amount of change, In the one or other measuring part Body rate and a conduit diameter, derived coefficient values based on a fluid pressure measuring apparatus characterized by determining the pressure of the fluid flowing in the conduit.

  According to this application example, the fluid pressure at the two measuring parts, the diameter of the conduit, and the coefficient value obtained from the distance between the measuring parts are first obtained, and thereafter the fluid pressure can be easily obtained. A fluid pressure measuring device can be provided.

  Application Example 2 The fluid pressure measuring device according to claim 1, further comprising an elevation difference determining unit that determines a distance in a gravity (vertical) direction between the two measuring units.

  According to this application example, it is possible to easily determine the height difference, which is one factor when obtaining the water head pressure.

  Application Example 3 In the fluid pressure measurement device, the distance in the gravity direction between the two measurement units is an inclination angle between the separation distance between the two measurement units and the gravity direction of the two measurement units. The fluid pressure measuring device calculated by the following.

  According to this application example, it is possible to easily obtain the height difference, which is one element when obtaining the water head pressure, without depending on the spatial arrangement of the two measurement units.

  Application Example 4 In a state where a predetermined first portion of the measurement target portion including a conduit through which a fluid flows is positioned at a predetermined height, the fluid velocity of the first portion is guided to the first portion. A pressure of the fluid proportional to a predetermined coefficient value with respect to a value divided by the square of the tube diameter, the calibration step for obtaining the coefficient value, and in the state, the conduit diameter of the first portion and Measuring each of the fluid velocities, measuring a conduit diameter and a fluid velocity at a predetermined second part of the measurement target portion in the state, and a conduit diameter of the first part, the first part A step of determining the pressure using a fluid velocity at one part and the coefficient value; a step of displaying the pressure; and a step of determining whether calibration of the coefficient value is necessary. Fluid pressure measurement method.

  According to this application example, the fluid pressure can be accurately measured without using another pressure measuring device for calibration.

  Application Example 5 In the above fluid pressure measurement method, the calibration step is performed in the state where the first part is positioned at the height of the pressure reference surface of the fluid, and the conduits of the first and second parts. Measuring the time variation of the diameter to obtain an average conduit diameter, measuring the time variation of the fluid velocity at the first portion, and the time variation of the conduit diameter and the fluid velocity at the first portion. Determining the conduit diameter and fluid velocity at the maximum and minimum pressures, and using the average conduit diameter at the first portion and the average conduit diameter at the second portion A step of obtaining a change in diameter; a height difference measuring step of measuring a height difference between the first part and the second part in the state; and the first part and the second part using the height difference. Determining the head pressure between the head pressure, the head pressure, the average conduit diameter change, the conduit diameter at the maximum pressure, and Obtaining a pressure difference between the maximum pressure and the minimum pressure using the conduit diameter at the minimum pressure, and the pressure difference, the fluid velocity at the maximum pressure, the conduit diameter at the maximum pressure, and the minimum And a step of obtaining the coefficient value using a fluid velocity at the time of pressure and a conduit diameter at the time of the minimum pressure.

  According to this application example, the coefficient value can be easily calibrated without using another pressure measuring device.

  Application Example 6 A blood pressure measurement apparatus including at least two measurement units that are arranged apart from each other along the longitudinal direction of the conduit of the measurement target unit, and a control unit that controls the measurement unit, The measurement unit includes a measurement medium transmission / reception unit that transmits a measurement medium to the measurement target unit, and acquires a part of the measurement medium returned from the measurement target unit, and the control unit includes the one and the other of the measurement medium The measurement unit measures the velocity of blood flow and the blood vessel diameter flowing in the blood vessel existing in the measurement target unit, the change amount of the blood vessel diameter measured in the at least one measurement unit, the one measurement unit and the other A change in blood pressure derived based on a difference in blood vessel diameter at the measurement unit and a hydrocephalic difference derived based on a distance between the two measurement units. Blood in the other measuring unit Speed and the vessel diameter, derive coefficients based on the blood pressure measurement device characterized by determining the pressure of the blood flow flowing through the vessel.

  According to this application example, a blood pressure measurement device that can first obtain a blood pressure simply by obtaining a coefficient value obtained from a blood flow velocity, a blood vessel diameter, and a distance between the measurement units at two measurement units first. Can provide.

  Application Example 7 The blood pressure measurement device according to the above-described blood pressure measurement device, further comprising a height difference determination unit that determines a distance in the gravity direction between the two measurement units.

  According to this application example, it is possible to easily determine the height difference, which is one factor when obtaining the water head pressure.

  Application Example 8 In the blood pressure measurement device, the distance in the gravitational direction between the two measurement units depends on an inclination angle between the separation distance between the two measurement units and the gravity direction of the two measurement units. A blood pressure measurement device characterized by being calculated.

  According to this application example, it is possible to easily measure the height difference, which is an element when obtaining the hydraulic head pressure, without depending on the spatial arrangement of the two measurement units.

  Application Example 9 With the predetermined first part of the measurement subject positioned at a predetermined height, the blood flow velocity of the predetermined first part is divided by the square of the blood vessel diameter of the first part. A blood pressure of the measurement subject that is proportional to a value by a predetermined coefficient value, and the blood vessel diameter and the blood flow velocity of the first part are measured in the calibration step for obtaining the coefficient value and in the state, respectively. A step of measuring a blood vessel diameter and a blood flow velocity at a predetermined second site of the subject in the state, a blood vessel diameter of the first site, a blood flow velocity of the first site, A blood pressure measurement method comprising: obtaining the blood pressure using the coefficient value; displaying the blood pressure; and determining whether calibration of the coefficient value is necessary.

  According to this application example, the blood pressure can be accurately measured without using a cuff sphygmomanometer, and the cuff sphygmomanometer is not used even during calibration. The load when measuring can be reduced.

  [Application Example 10] In the blood pressure measurement method, the calibration step may be performed with the blood vessel diameters of the first and second sites in a state where the first site is positioned at the height of the heart of the subject. From the steps of measuring temporal changes to determine the average blood vessel diameter, measuring the temporal changes in blood flow velocity at the first site, and temporal changes in blood vessel diameter and blood flow velocity at the first site, A step of obtaining a blood vessel diameter and a blood flow velocity at the time of hypertension and a minimum blood pressure, and a step of obtaining an average blood vessel diameter change using the average blood vessel diameter at the first site and the average blood vessel diameter at the second site. And in the state, a height difference measuring step for measuring a height difference between the first part and the second part, and a hydrohead pressure between the first part and the second part using the height difference. Determining the head pressure, the change in mean blood vessel diameter, the blood vessel diameter at the highest blood pressure, and Obtaining a blood pressure difference between the highest blood pressure and the lowest blood pressure using the blood vessel diameter at the lowest blood pressure; and the blood pressure difference, the blood flow velocity at the highest blood pressure, the blood vessel diameter at the highest blood pressure, and the lowest blood pressure. Blood flow velocity and obtaining the coefficient value using the blood vessel diameter at the time of the lowest blood pressure.

  According to this application example, the coefficient value can be easily calibrated without using a cuff type sphygmomanometer.

The external view which shows the state with which the blood-pressure measuring apparatus which concerns on this embodiment was mounted | worn with the human body. The figure which shows the blood flow velocity sensor and blood vessel diameter sensor which concern on this embodiment. The figure which shows the circuit block which concerns on this embodiment. The figure which shows the blood-pressure fluctuation | variation and blood-vessel diameter fluctuation | variation which concern on this embodiment. The figure which shows the measuring method which concerns on this embodiment. The figure which shows the calibration routine which concerns on this embodiment.

  An embodiment will be described with reference to the drawings. Note that the drawings to be used are appropriately enlarged or reduced so that the part to be described can be recognized.

  FIG. 1 is an external view showing a state in which a blood pressure measuring device as a fluid pressure measuring device according to this embodiment is attached to a human body. In this case, it is assumed that the fluid pressure measuring device is the blood pressure measuring device 1 and the blood pressure of the brachial artery (blood vessel) 5 is measured. The blood pressure measurement device 1 is attached to the upper arm of the person to be measured 3, and obtains the blood pressure value P as the fluid pressure by measuring the blood flow velocity v of the brachial artery 5 as the fluid velocity and the blood vessel diameter D as the conduit diameter. .

  As shown in FIG. 1, sensors 6 and 8 as two measuring units are respectively attached to a predetermined first part and a predetermined second part of the upper arm using a band 2 or the like. As long as the sensors 6 and 8 can be fixed to the measurement site for attachment to the upper arm, instead of the band 2, a sealing material or the like having adhesiveness with the skin may be used. Desirably, one of the sensor positions is at the same height as the position of the heart 4 of the person to be measured 3, and if a sensor having the same height is used for blood pressure measurement at all times, the head pressure correction of the blood pressure value becomes unnecessary. In this embodiment, the sensor 6 has the same height as the heart 4. However, even if the height position is not the same as that of the heart 4, if the height difference from the heart 4 is obtained in advance, the blood pressure can be correctly obtained by correcting the head difference. In other words, measurement is possible without using the upper arm as in the embodiment.

  FIG. 2 is a diagram illustrating a blood flow velocity sensor 10 and a blood vessel diameter sensor 20 as measurement units according to the present embodiment, and FIG. 3 is a diagram illustrating a circuit block according to the present embodiment. As shown in FIG. 2, each of the sensors 6 and 8 includes a blood flow velocity sensor 10 and a blood vessel diameter sensor 20, and blood flow velocity v and blood vessel diameter D at positions H and L in FIG. Is measured. As long as blood flow velocity sensor 10 and blood vessel diameter sensor 20 included in sensors 6 and 8 can be measured simultaneously by one sensor, one sensor may be substituted. In the present embodiment, the measurement of the blood flow velocity at the position L is unnecessary.

  The blood flow velocity sensor 10 is attached to the brachial artery 5 on the inner side of the upper arm so that an ultrasonic wave can be irradiated as a measurement medium. As shown in FIG. 3, the blood flow velocity sensor 10 includes a blood flow velocity sensor unit 15, a blood flow velocity sensor drive unit 11, and a signal calculation unit 14. The blood flow rate sensor unit 15 transmits and receives waves from the surface of the living body of the person to be measured 3 to the blood inside the living body, and detects the blood flow inside the living body. The blood flow velocity sensor unit 15 includes a transmission unit 12 (transmission element) and a reception unit 13 (reception element). The drive unit 11 drives the blood flow velocity sensor unit 15. The signal calculation unit 14 controls the driving unit 11 and the blood flow velocity sensor unit 15 to obtain the blood flow velocity v inside the living body. The signal calculation unit 14 calculates the blood flow velocity v at each time at the position L based on the Doppler method. As the Doppler method, an optimum method such as a continuous wave Doppler method, a pulse wave Doppler method, a color flow mapping method, or the like can be used in consideration of a measurement site and resolution.

  The blood vessel diameter sensor 20 is attached to a position where ultrasonic waves can be irradiated as a measurement medium to the brachial artery 5 inside the brachial part. As shown in FIG. 3, the blood vessel diameter sensor 20 includes a blood vessel diameter sensor unit 25, a blood vessel diameter sensor drive unit 21, and a blood vessel diameter sensor signal calculation unit 24. The blood vessel diameter sensor unit 25 includes a transmission unit 22 and a reception unit 23. The blood vessel diameter sensor unit 25 transmits and receives ultrasonic waves to and from the brachial artery 5 inside the living body, and detects a change in the wall of the brachial artery 5 inside the living body. The drive unit 21 drives the blood vessel diameter sensor unit 25. The signal calculation unit 24 controls the driving unit 21 and the blood vessel diameter sensor unit 25 to obtain the blood vessel diameter D inside the living body.

  The blood vessel diameter sensor 20 transmits a pulse signal or burst signal of several MHz, and calculates the diameter of the blood vessel from the phase change of the reflected reception wave from the tube wall. This is called echo tracking technology. Specifically, the pulsations of the anterior wall and the posterior wall of the blood vessel are detected in the two tracking gates, and the diameter is calculated from the variation of each wall (reference document: JP-B-61). No.-28336). In the embodiment, an ultrasonic wave is used as a measurement medium. However, the present invention is not limited to this, and a laser, coherent light, or the like may be used.

  The blood pressure measurement device 1 according to the present embodiment includes a blood pressure value calculation unit 43, a display unit 41, a height difference determination unit 30, a switch 42, an operation panel 44, and a power supply unit 40. The blood pressure value calculation unit 43 obtains the blood pressure value P of the person to be measured 3 using the calculation results of the signal calculation unit 14 and the signal calculation unit 24 of the sensor 6 (which is the same height as the heart). The display unit 41 displays the blood pressure value P of the person to be measured 3. It can also be visualized and displayed on a graph or the like. Further, the pulse may be displayed in the same manner. Furthermore, it is displayed that calibration is necessary. The height difference determination unit 30 determines the height difference between the sensors 6 and 8 of the blood pressure measurement device 1. The switch 42 switches supply / cut-off of power from the power supply unit 40 to each functional unit of the blood pressure measurement device 1. The operation panel 44 can be operated on the display unit 41 to display the measured blood pressure, switch to a pulse, or switch to past logging data display. The power supply unit 40 supplies power to each functional unit of the blood pressure measurement device 1. In the present embodiment, for example, a rechargeable secondary battery is assumed.

  Next, the principle of deriving the blood pressure value P used in this embodiment will be described.

The blood pressure value P is expressed as follows using the blood flow Q and the blood flow resistance R.
Blood pressure value P = blood flow volume Q × blood flow resistance R
Blood flow rate Q = (π × D ² × v) / 8 (1)
Blood flow resistance R = η × C / D ⁴ (2)
At this time, D is a blood vessel diameter, v is a blood flow velocity, η is a blood viscosity, and C is a coefficient. In summary, the blood pressure value P can be expressed as follows.
P = π / 8 × η × C × v / D ² (3)
That is, if (π / 8 × η × C) is obtained as a certain coefficient value, the blood pressure value P at that time can be obtained by obtaining the blood flow velocity v and the blood vessel diameter D.

  In the conventional method, the actual blood pressure is measured in advance using a cuff type sphygmomanometer or the like, and the coefficient value is calibrated. In the following, the principle of calculating the coefficient value or performing timely calibration and deriving the blood pressure without requiring calibration with a cuff type sphygmomanometer will be described.

A calibration method (calculation of coefficient value π / 8 × η × C) will be described.
As shown in FIG. 1, at least the following parameters 1) to 3) are measured by two sensors 6 and 8 attached to different height positions H and L of the upper arm.
1) Blood vessel diameter change at one height or more at height position H and average blood vessel diameter D _Hm at that time.
2) The change in blood vessel diameter at one height or more at the height position L and the average blood vessel diameter D _Lm at that time.
3) Change in blood flow rate at one height or more at the height position H.
Further, from the measurements of 1) and 2), the blood vessel diameter D _Hsys at the maximum blood pressure value P _sys (systolic blood pressure) and the blood vessel diameter D at the minimum blood pressure value P _dia (diastolic blood pressure) at the height position H. _Hdia is obtained, and at the same time, a difference ΔD _m (= D _Lm −D _Hm ) between D _Hm and D _Lm is also obtained. Further than 3), at position H, and the blood flow velocity v _Hsys in systolic blood P _sys, obtained blood flow velocity v _Hdia in diastolic blood pressure P _dia.

Next, a differential pressure (change amount of the blood pressure value) P _sys -P _dia between the maximum blood pressure value and the minimum blood pressure value is obtained.
FIG. 4 is a diagram showing blood pressure fluctuations and blood vessel diameter fluctuations according to the present embodiment. The relationship between the fluctuation of the blood vessel diameter D at the height positions H and L and the fluctuation of the blood pressure value P is as shown in FIG. Since the difference in the blood vessel diameter D between the positions H and L at the same blood pressure value P is considered to be a difference due to the hydrocephalic pressure, it depends on the average blood vessel diameter difference ΔD _m and the height difference h between the height positions H and L. The water head pressure ρgh (water head pressure, ρ: blood density, g: gravitational acceleration) uniquely corresponds. Thus, considering the difference between the maximum blood pressure value and the minimum blood pressure value (P _sys −P _dia ) and the difference in blood vessel diameter D (D _Hsys −D _Hdia ) at that time, the following relationship is approximately established.

(P _sys −P _dia ): ρgh = (D _Hsys −D _Hdia ): ΔD _m (4)
_Therefore , the differential pressure P _sys -P _dia is
P _sys −P _dia = ρgh × (D _Hsys −D _Hdia ) / ΔD _m (5)
Further, when the systolic blood pressure value P _sys and the diastolic blood pressure value P _dia at the position H are obtained from the expression (3),
P _sys = π / 8 × η × C × v _Hsys / D _Hsys ² (6)
P _dia = π / 8 × η × C × v _Hdia / D _Hdia ² (7)
Therefore, the differential pressure can also be written as
P _sys −P _dia = π / 8 × η × C × (v _Hsys / D _Hsys ² −v _Hdia / D _Hdia ² ) (8)
From the equation (8), the coefficient value (π / 8 × η × C) can be calculated by the following equation.
π / 8 × η × C = (P _sys −P _dia ) / (v _Hsys / D _Hsys ² −v _Hdia / D _Hdia ² ) (9)
Further, the coefficient value (π / 8 × η × C) can be written as follows from equations (9) and (5).
π / 8 × η × C = ρgh × (D _Hsys −D _Hdia ) / {ΔD _m × (v _Hsys / D _Hsys ² −v _Hdia / D _Hdia ² )} (10)

  As described above, the blood pressure value P can be easily obtained by substituting the time-measured blood vessel diameter D, the blood flow velocity v at that time, and the coefficient value (π / 8 × η × C) obtained as described above into the equation (3). be able to.

FIG. 5 is a diagram showing a blood pressure measurement method according to the present embodiment.
First, after the switch 42 is turned on, calibration for calculating the coefficient value (π / 8 × η × C) is performed as shown in step S10. Details of step S10 will be described later.
Subsequently, as shown in step S20, the blood vessel diameter D and the blood flow velocity v are measured. As a measuring method, a method of measuring the blood vessel diameter D by the above-described echo tracking method or a method of measuring the blood flow velocity v by the Doppler method is used.

  Next, in step S30, the blood pressure value P is calculated using the coefficient value (π / 8 × η × C) obtained by the calibration routine in step S10. The temporal change of the blood pressure value P can also be calculated by obtaining temporal changes in the blood vessel diameter D and the blood flow velocity v at the same location and at the same time.

  Next, as shown in step S40, the blood pressure value P obtained in step S30 is displayed on the display unit 41. Further, it can be visualized by a graph or the like and displayed on the display unit 41. Further, the pulse may be displayed in the same manner.

At this stage, as shown in step S50, it is determined whether calibration is necessary again. If necessary, return to step S10 and perform calibration. If not necessary, the process proceeds to step S60. The case where calibration is necessary is, for example, a case where the maximum blood pressure value changes by ± 15 mmHg or more compared to normal. In this case, a recalibration instruction is displayed on the display unit 41.
Finally, as shown in step S60, it is determined whether it is necessary to continue the measurement. If necessary, the process returns to step S20 to measure the blood vessel diameter D and the blood flow velocity v. Exit if not needed. As a result, calibration can be easily performed without using a cuff-type sphygmomanometer, and the measurement subject can constantly measure blood pressure under free action.

  FIG. 6 is a calibration routine according to the present embodiment and is a diagram showing in detail step S10 of FIG.

First, as shown in step S11, the blood vessel diameter D at the height positions H and L in FIG. 1 is measured, and at the same time, the average blood vessel diameters D _Hm and D _Lm are calculated. The average blood vessel diameters D _Hm and D _Lm may be specified within one heartbeat, or a change in blood vessel diameter D may be measured for about 10 seconds, and an ensemble average for a plurality of heartbeats may be calculated and acquired.

  Next, in step S12, the blood flow velocity v at the height position H in FIG. 1 is measured. The measurement of blood flow velocity v is preferably as close as possible to the change in blood vessel diameter measured in step S11.

Next, as shown in step S13, the blood vessel diameter D _Hsys and blood corresponding to the maximum blood pressure value are obtained from the temporal change of the blood vessel diameter D and the blood flow velocity v at the height position H measured in steps S11 and S12. The flow velocity v _Hsys , the blood vessel diameter D _Hdia corresponding to the minimum blood pressure value, and the blood flow velocity v _Hdia are calculated.

Next, as shown in step S14, mean vessel diameter D _Hm calculated in step S11, from D _Lm, and calculates the mean vessel diameter change [Delta] D _m.

  Here, as shown in step S15, the hydraulic head pressure (ρgh) is calculated. Details of the calculation of the water head pressure and the method for determining the height difference h will be described later.

Then, as shown in step S16, and calculates the blood pressure difference between the diastolic blood pressure value P _dia and systolic P _sys the (P _sys -P _dia). At the height position H of FIG. 1, and the blood vessel diameter D _Hsys in systolic blood P _sys, the use of vascular diameter D _Hdia in the diastolic blood pressure P _dia, the equation (5) by transforming the equation (4) The blood pressure difference (P _sys −P _dia ) between the minimum blood pressure value P _dia and the maximum blood pressure value P _sys is calculated.

Finally, as shown in step S17, the blood pressure difference calculated in step S16 in equation (9) and (P _sys -P _dia), at a height position H calculated in step S13, corresponding to the systolic blood pressure value P _sys A coefficient value (π / 8 × η × C) is calculated from the blood vessel diameter D and the blood flow velocity v corresponding to the blood vessel diameter D, the blood flow velocity v, and the minimum blood pressure value _Pdia .

  A method for calculating the hydraulic head pressure necessary for calculating the coefficient value (π / 8 × η × C) will be described.

In order to obtain the water head pressure ρgh, in addition to the gravitational acceleration g (≈9.8 m / s ² ), the blood density and the height difference h are required. Since the density ρ of blood is about 1.055 ± 0.005 g / cm ³ between men and women, the effect on blood pressure is ± 0.00. Since it is several mmHg, it is assumed to be constant here. That is, it is necessary to accurately measure the height difference h in order to accurately determine the water head pressure. As shown in FIG. 1, the height difference h can be obtained by measuring the distance between the sensors 6 and 8 with a ruler in advance. Alternatively, if the sensors 6 and 8 are connected by a fixing member having an arbitrary length, the arbitrary length can be set to a height difference. By the way, if the measurement target parts are aligned in the vertical direction, there is no problem in the determination method. However, when the measurement target part is inclined from the vertical direction, an error occurs. In that case, the angle of the sensor 6 or 8 can be detected by an inclination sensor or the like, and the height difference h can be calculated from the distance between the detected angle and the sensors 6 and 8. Alternatively, in a micro air pressure sensor using a quartz device, there is a possibility that the height difference h can be measured with a resolution on the order of mm. If this is used, the height difference h can be easily measured with high accuracy. It can be considered that the measurement target portion tilts from the vertical direction frequently when the measurement subject 3 performs timely calibration under free action. Therefore, it is considered that the technique as described above is likely to be required when the measurement subject 3 performs measurement under free action. In addition, the said method is an example to the last, and if the height difference h can be calculated | required correctly with a certain method, a hydraulic head pressure can also be calculated accurately. Actually, if the height difference h is considered to be about 15 cm at the upper arm, the hydraulic head pressure is about 11.6 mmHg.

  In the present embodiment, the position H of the sensor 6 is the height position of the heart 4. However, even if the height of the heart 4 is different from the position H, if the height difference h from the heart 4 is obtained in advance, the water head The blood pressure value P can be calculated by adding and subtracting the pressure as in the above embodiment. In the present embodiment, the blood pressure is calculated as the fluid pressure assuming that the measurement target is a living body, but the present invention is not limited to this.

  According to the fluid pressure measuring device and the fluid pressure measuring method of the present embodiment, timely calibration can be simplified without using another pressure measuring device, and the fluid pressure P can be measured with high accuracy. Moreover, when it is applied to a living body, a coefficient value for calculating blood pressure can be calibrated in a timely manner without using a cuff type sphygmomanometer. Can be provided.

  DESCRIPTION OF SYMBOLS 1 ... Blood pressure measuring device 2 ... Band 3 ... Person to be measured 4 ... Heart 5 ... Brachial artery (blood vessel) 6, 8 ... Sensor 10 ... Blood flow rate sensor (measurement unit) 11 ... Drive unit (blood flow rate sensor drive unit) DESCRIPTION OF SYMBOLS 12 ... Transmitting part (transmission element) 13 ... Reception part (receiving element) 14 ... Signal calculation part (blood flow velocity sensor signal calculation part) 15 ... Blood flow velocity sensor part 20 ... Blood vessel diameter sensor (measurement part) 21 ... Driving unit (blood vessel diameter sensor driving unit) 22 ... Transmitting unit (transmitting element) 23 ... Receiving unit (receiving element) 24 ... Signal calculating unit (blood vessel diameter sensor signal calculating unit) 25 ... Blood vessel diameter sensor unit 30 ... Height difference Determination unit 40 ... power supply unit 41 ... display unit 42 ... switch 43 ... blood pressure value calculation unit 44 ... operation panel.

Claims (2)

A plurality of measurement units for measuring a heartbeat systolic blood vessel diameter and a heartbeat diastole blood vessel diameter for a plurality of heartbeats by transmitting ultrasonic waves to the blood vessel and reflecting from the blood vessel ;
Calculating an average value of the systolic blood vessel diameter of the heartbeat as an average systolic blood vessel diameter, and calculating an average blood vessel diameter of the heartbeat diastole as an average diastolic blood vessel diameter;
An average blood vessel diameter difference calculating unit for calculating a difference between the average diastolic blood vessel diameter and the average systolic blood vessel diameter as an average blood vessel diameter difference;
A head difference calculation unit that calculates a head difference according to the distance between the plurality of measurement units;
A pulse pressure calculating section for calculating pulse pressure which is the difference between the maximum value and the minimum value of the blood pressure of the blood vessel using said water head difference between the average vessel diameter difference,
Having
A pulse pressure measuring device characterized by that. The ultrasonic wave transmitted to the blood vessel and reflected from the blood vessel is obtained by dividing the blood vessel diameter of the blood vessel in the systole of the heartbeat and the blood vessel diameter of the blood vessel in the diastole of the heartbeat by a plurality of heartbeats. The process of measuring at the measurement point of
Calculating the average systolic blood vessel diameter of the heartbeat as a systolic blood vessel diameter, and calculating the average of the diastolic blood vessel diameter of the heartbeat as an average diastolic blood vessel diameter;
Calculating a difference between the average systolic blood vessel diameter and the average diastolic blood vessel diameter as an average blood vessel diameter difference;
Calculating a water head difference according to a distance between a plurality of measurement points of the blood vessel;
Calculating a pulse pressure that is a difference between a maximum value and a minimum value of the blood pressure of the blood vessel using the average blood vessel diameter difference and the hydrocephalic difference;
A method for measuring pulse pressure, comprising :