JP5228619B2 - Blood pressure measurement device - Google Patents

Description

  The present invention relates to a blood pressure measurement device, and more particularly to a blood pressure measurement device that measures blood pressure using an arm band (cuff) that encloses a fluid bag.

  As one of the blood pressure calculation methods adopted by the electronic sphygmomanometer, by reducing the pressure of the arm band (cuff) that encloses the fluid bag wrapped around a part of the living body, the fluid bag transmitted from the volume change of the compressed blood vessel There is an oscillometric method for calculating a blood pressure by taking a volume change as a pressure change (pressure pulse wave amplitude) of a fluid bag.

The fluid bag has such a characteristic that the pressure of the fluid bag and the volume of the fluid bag have a relationship as shown in FIG. That is, with reference to FIG. 15, in the region where the pressure of the fluid bag is low, which is shown in the portion A, the volume of the fluid bag increases rapidly as the pressure of the fluid bag increases. Further, as shown in part B, as the pressure of the fluid bag increases, the increase rate of the volume of the fluid bag gradually decreases as the pressure of the fluid bag increases. FIG. 16 shows a change in volume of the fluid bag (B) accompanying a change in volume of the blood vessel (A) when the fluid density in the fluid bag is low, and FIG. It is a figure showing the change (C) of a fluid density, and the pressure change (D) of a fluid bag. 18 shows a case where the discharge speed of the fluid exiting from the fluid bag is fast, that is, when the discharge amount per unit time is large, and FIG. 19 shows a case where the discharge speed of the fluid exiting from the fluid bag is slow, that is, the discharge amount per unit time. It is a figure showing the volume change (B) of the fluid bag accompanying the volume change (A) of the blood vessel when there is little, and the pressure change (C) of the fluid bag. 16-19, it can be read that the detection accuracy of the blood vessel volume change has the following characteristics:
(1) The higher the pressure of the fluid bag, the higher the density of the fluid in the fluid bag.
(2) The larger the volume of the fluid bag, the smaller the density change of the fluid in the fluid bag due to the volume change of the blood vessel, so the detection accuracy of the volume change of the blood vessel is lower.
(3) When the volume change of the fluid bag is the same, the higher the pressure of the fluid bag, the greater the density change of the fluid in the fluid bag accompanying the volume change of the fluid bag, so the detection accuracy of the volume change of the blood vessel becomes higher.
(4) Even if the pressure of the fluid bag is the same, the magnitude of the change in volume of the fluid bag due to the change in volume of the blood vessel changes depending on the amount of fluid discharged in the fluid bag. ,
(5) The greater the amount of fluid discharged in the fluid bag, the smaller the change in volume of the fluid bag due to the change in volume of the blood vessel, and the lower the detection accuracy of the change in volume of the blood vessel.

  Therefore, in the electronic sphygmomanometer using the oscillometric method, the detection accuracy of the volume change of the blood vessel depends on the density of the fluid in the fluid bag and the discharge amount of the fluid from the fluid bag.

  As shown in FIG. 20, a sphygmomanometer that depressurizes the fluid bag at a constant speed, according to the pressure of the fluid bag and the circumference of the measurement site, in order to depressurize at a constant speed (FIG. 20A). The amount of fluid discharged from the fluid bag was controlled by a valve ((B) of FIG. 20). Accordingly, as shown in FIG. 20C, the pressure pulse wave amplitude with respect to the constant volume change of the blood vessel is large in the region where the pressure of the fluid bag is high, and the constant volume of the blood vessel in the region where the pressure of the fluid bag is low. The pressure pulse wave amplitude with respect to the change was small. In addition, since the amount of change in the volume of the blood vessel accompanying the change in the pressure of the fluid bag differs depending on the circumference of the measurement site, these have become an error factor in blood pressure measurement.

  As a technique for solving these problems, the following method is disclosed. That is, Japanese Patent Laid-Open No. 6-245911 (Patent Document 1) discloses a technique for adjusting the discharge amount of a valve in accordance with the circumference of a measurement site, or a fluid storage portion that communicates with a fluid bag, and a measurement site for a fluid bag. A technique is disclosed in which the volume sum of the fluid bag and the fluid storage portion is controlled to be constant according to the winding circumference. As a result, it is possible to keep the decompression speed constant even if the circumferences of the measurement sites are different.

  Japanese Patent No. 3113737 (Patent Document 2) prepares in advance a volume change characteristic of the fluid bag with respect to the pressure of the fluid bag, converts the pressure change signal of the fluid bag into a volume change, and uses it. A method for measuring a blood pressure value is disclosed.

Japanese Patent Laid-Open No. 4-250133 (patent document 3) discloses that in a pulse wave appearance section, a valve that discharges fluid in a fluid bag is closed to prevent attenuation of blood vessel volume change accompanying volume change of the fluid bag. A method is disclosed.
JP-A-6-245911 Japanese Patent No. 3113737 JP-A-4-250133

  However, although the method disclosed in Patent Document 1 can eliminate the difference in pressure reduction speed due to the difference in circumference of the measurement site, the valve is discharged in conjunction with the pressure of the fluid bag in order to keep the pressure reduction speed constant. As the amount changes, the pressure pulse wave amplitude changes according to the pressure of the fluid bag. For this reason, even if the volume sum of the fluid bag and the fluid storage portion is controlled to be constant, the difference in volume due to the circumference of the measurement site is eliminated. The size changes. Therefore, there is still a problem that an error occurs in blood pressure measurement.

  Moreover, in the method disclosed in Patent Document 2, it is necessary to give the pressure and volume change characteristic of the fluid bag in advance. However, since this change characteristic changes infinitely depending on how the fluid bag is wound, the thickness of the arm, the softness of the human body, etc., there is a problem that sufficient correction cannot be performed. In addition, a plurality of more complicated corrections (flow rate detection, measurement site size detection, winding state detection, human body softness detection, etc.) are required, and a large-scale device is required, which is not practical.

  Further, the method disclosed in Patent Document 3 can accurately grasp the change in the volume of the blood vessel as the change in the pressure of the fluid bag, but it is difficult to reduce the pressure because the valve is closed each time a pulse wave appears. There is a problem.

  In other words, in the methods disclosed in these patent documents, the pressure and volume of the fluid bag are not proportional to each other. Therefore, when measuring blood pressure while reducing the pressure, the fluid volume depends on the circumference of the measurement site or the pressure of the fluid bag. The flow rate of the fluid discharged from the bag was different. Thereby, the detection accuracy of the pressure pulse wave amplitude with respect to the change in the volume of the blood vessel differs depending on the circumference of the measurement site and the pressure of the fluid bag. Therefore, there is a problem that even if the volume change of the blood vessel is the same, an error occurs in the magnitude of the pressure pulse wave amplitude depending on the blood pressure value and the circumference of the measurement site, and the accuracy of blood pressure measurement is reduced.

  The present invention has been made in view of such problems, and by making the flow rate of the fluid exiting the fluid bag proportional to the pressure reduction rate, the pressure pulse wave amplitude with respect to a constant blood vessel volume change is made constant. An object of the present invention is to provide a blood pressure measurement device that can be brought close to and can improve the accuracy of blood pressure measurement.

  In order to achieve the above object, according to an aspect of the present invention, a blood pressure measurement device includes a fluid bag, pressurizing means for injecting and pressurizing fluid into the fluid bag, and discharging the fluid from the fluid bag to decompress the fluid. A pressure reducing means, a sensor for measuring a change in the internal pressure of the fluid bag, and a blood pressure measuring means for calculating a blood pressure value based on a change in the internal pressure of the fluid bag obtained by the sensor in a pressure reducing process for discharging the fluid from the fluid bag by the pressure reducing means. , A pressure means, a pressure reduction means, and a control means for controlling the blood pressure measurement means. The control means discharges the fluid in the pressure reduction means so that the discharge amount is proportional to the pressure reduction speed of the fluid bag in the pressure reduction process. The control amount for controlling the amount is determined, and the discharge amount is controlled.

  Preferably, the pressure reducing means includes a valve provided in the fluid bag, the control amount is a valve gap, and the control means controls the discharge amount by controlling the valve gap to be held in the determined gap in the pressure reducing process. Control.

  More preferably, the control means determines the gap of the valve, which is a control amount, so that the pressure reduction rate includes a predetermined number or more of the pulse rate within the time when the internal pressure of the fluid bag changes from the highest blood pressure to the lowest blood pressure. More preferably, the predetermined number is “5”, and the control means determines a valve gap which is a control amount at which the decompression speed becomes 3 mmHg / sec to 13 mmHg / sec.

  Preferably, the control means includes acquisition means for acquiring information related to the circumference of the measurement site, and the control means determines a valve gap which is a control amount according to the circumference.

  More preferably, the blood pressure measurement device further includes input means for inputting a circumference, and the acquisition means acquires information about the circumference by input from the input means.

  Preferably, the acquisition unit acquires information on the circumference based on a pressurization time in the pressurization unit until the internal pressure of the fluid bag becomes a predetermined pressure.

  Preferably, the pressurizing means includes a pump, and the acquiring means acquires information on the circumference based on the rotational speed of the pump and the internal pressure of the fluid bag.

  Preferably, the blood pressure measurement device further includes winding means for winding the fluid bag around the measurement site, the winding means includes a slide resistance, and the acquisition means slides by winding the fluid bag around the measurement site with the winding means. Information on the circumference is acquired based on the resistance value obtained from the resistance.

  Preferably, the blood pressure measurement means further calculates a blood pressure value based on a change in the internal pressure of the fluid bag obtained by the sensor in the pressurization process in which the fluid is injected into the fluid bag by the pressurization means, and the control means further includes the pressurization process. The valve gap, which is a controlled variable, is determined in accordance with the blood pressure value calculated based on the change in the internal pressure of the fluid bag.

  More preferably, the blood pressure measurement means further calculates a period of the pulse wave based on a change in the internal pressure of the fluid bag obtained by the sensor in a pressurizing process in which fluid is injected into the fluid bag by the pressurizing means, and the control means The valve gap is determined according to the period of the pulse wave calculated based on the change in the internal pressure of the fluid bag in the pressurizing process.

  Preferably, the blood pressure measurement device further includes a measurement unit that measures the discharge amount, and the control unit discharges the pressure in the decompression process based on the discharge amount measured by the measurement unit and the change in the internal pressure of the fluid bag obtained by the sensor. The amount of fluid discharged from the decompression means is controlled so that the amount is proportional to the decompression speed of the fluid bag.

  Preferably, the blood pressure measurement device further includes an increasing means for increasing the capacity of the fluid bag, and the pressurizing means injects and pressurizes the fluid into the fluid bag whose volume is increased by the increasing means.

  More preferably, the increasing means includes injecting means for injecting the incompressible fluid into the fluid bag, and the control means fluidizes the incompressible fluid with the injecting means before injecting the fluid into the fluid bag with the pressurizing means. Control to fill the bag.

  More preferably, the control means controls to inject a predetermined amount of incompressible fluid into the fluid bag by the injecting means before injecting the fluid into the fluid bag by the pressurizing means.

  Preferably, the control means is prior to injecting the fluid into the fluid bag with the pressurizing means until the pressure of the fluid bag reaches a predetermined pressure or until the pressurization rate of the fluid bag reaches a predetermined pressurization speed. The step of injecting the incompressible fluid into the fluid bag by the injection means, and the pressure of the fluid bag after the pressure of the fluid bag reaches a predetermined pressure or after the pressurization speed of the fluid bag reaches the predetermined pressurization speed. And a step of opening the fluid bag to the atmospheric pressure and a step of closing the fluid bag and starting the injection of the fluid by the pressurizing means after the pressure of the fluid bag is set to the atmospheric pressure.

  Preferably, the blood pressure measurement device includes a filter that allows fluid to permeate and does not allow incompressible fluid to permeate at a portion connecting the fluid bag and the outlet for discharging the fluid by the decompression means.

  Preferably, the increasing means is a filling member disposed in the fluid bag, more preferably, the filling member includes any one of a sponge, a spring, and a microbead.

  According to the present invention, in the blood pressure measurement device, the detection accuracy of the volume change of the blood vessel can be made close to a constant regardless of the pressure of the fluid bag. Thereby, a blood pressure measurement error can be reduced. Further, even if the volume of the fluid bag varies depending on the circumference of the measurement site, the rate of change in the detection accuracy of the change in volume of the blood vessel can be made close to a constant value. Thereby, a blood pressure measurement error can be reduced. Further, this eliminates the need to correct the volume of the fluid bag that varies depending on the circumference of the measurement site.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, the same parts and components are denoted by the same reference numerals. Their names and functions are also the same.

[First Embodiment]
FIG. 1 is a block diagram showing a specific example of the hardware configuration of a sphygmomanometer 1 which is a blood pressure measurement device according to the first embodiment of the present invention. Referring to FIG. 1, a sphygmomanometer 1 includes a main body 2 and a cuff 5 wound around a measurement site, which are connected by a tube 10. On the front surface of the main body 2, an operation unit 3 such as a switch and a display unit 4 for displaying measurement results and the like are arranged. The operation unit 3 includes a power switch 31 for instructing power ON / OFF, a measurement switch 32 for instructing start of measurement, a stop switch 33 for instructing stop of measurement, and a recorded measurement. A record recall switch 34 for recalling and displaying values is included. A fluid bag 13 is disposed in the cuff 5. For example, air corresponds to the fluid injected into the fluid bag 13 and discharged from the fluid bag 13. The fluid bag 13 is pressed against the measurement site by winding the cuff 5 around the measurement site. Examples of the measurement site include an upper arm or a wrist.

  The fluid bag 13 is connected to a pressure sensor 23 that measures a change in the internal pressure of the fluid bag 13, a pump 21 that injects / discharges fluid from the fluid bag 13, and a valve 22. The pressure sensor 23, the pump 21, and the valve 22 are connected to an oscillation circuit 28, a pump drive circuit 26, and a valve drive circuit 27, respectively. Further, the oscillation circuit 28, the pump drive circuit 26, and the valve drive circuit 27 are Each is connected to a CPU (Central Processing Unit) 40 that controls the entire sphygmomanometer 1.

  The CPU 40 further includes a display unit 4, an operation unit 3, a memory 6 that stores a program executed by the CPU 40 and serves as a work area when executing the program, and a memory 7 that stores measurement results and the like. And a power source 53 are connected.

  The CPU 40 is driven by receiving power supply from the power supply 53. The CPU 40 includes a circumference information acquisition unit 41 and a valve drive voltage determination unit 43. These are formed in the CPU 40 when the CPU 40 executes a predetermined program stored in the memory 6 based on an operation signal input from the operation unit 3. The circumference information acquisition unit 41 acquires circumference information that is the size of the measurement site and inputs the circumference information to the valve drive voltage determination unit 43. The valve drive voltage determination unit 43 determines a voltage (hereinafter, drive voltage E) for driving the valve 22 based on the circumference information. The CPU 40 outputs a control signal corresponding to the drive voltage E determined by the valve drive voltage determination unit 43 to the valve drive circuit 27. Further, the CPU 40 executes a predetermined program stored in the memory 6 based on the operation signal input from the operation unit 3 and outputs a control signal to the pump drive circuit 26.

  The pump drive circuit 26 and the valve drive circuit 27 drive the pump 21 and the valve 22 according to the control signal. The pump 21 is driven by a pump drive circuit 26 according to a control signal from the CPU 40 and injects fluid into the fluid bag 13. The valve 22 has its opening / closing and opening width (hereinafter referred to as a gap) controlled by a valve drive circuit 27 according to a control signal from the CPU 40, and discharges the fluid in the fluid bag 13.

  The pressure sensor 23 is a capacitance type pressure sensor, and its capacitance value changes due to a change in the internal pressure of the fluid bag 13. The oscillation circuit 28 is converted into a signal having an oscillation frequency corresponding to the capacitance value of the pressure sensor 23 and input to the CPU 40. The CPU 40 executes a predetermined process based on the change in the internal pressure of the fluid bag 13 obtained from the pressure sensor 23, and outputs the control signal to the pump drive circuit 26 and the valve drive circuit 27 according to the result. Further, the CPU 40 calculates a blood pressure value based on the change in the internal pressure of the fluid bag 13 obtained from the pressure sensor 23, performs a process for displaying the measurement result on the display unit 4, and data and a control signal for displaying the measurement result. Are output to the display unit 4. Further, the CPU 40 performs a process for storing the blood pressure value in the memory 7.

  FIG. 2 is a flowchart showing a first specific example of processing executed at the timing when the measurement switch 32 is operated in the sphygmomanometer 1. The processing shown in the flowchart of FIG. 2 is realized by the CPU 40 executing a predetermined program stored in the memory 6.

  Referring to FIG. 2, CPU 40 monitors the input of an operation signal from operation unit 3, and when detecting that measurement switch 32 is operated, in step S <b> 101, circumference information acquisition unit 41 of CPU 40 determines the measurement site. The circumference information representing the circumference of the measurement site having the size of is acquired. Here, it is assumed that circumference information such as “thick” and “thin” is input at the time of measurement by a switch or the like constituting the operation unit 3, and the circumference information acquisition unit 41 is based on an operation signal from the operation unit 3. Circumference information shall be acquired.

  In addition, the acquisition method of the circumference information in the circumference information acquisition part 41 is not limited to the above-mentioned method. For example, as shown in FIG. 3 as a second specific example of the process executed at the timing when the measurement switch 32 is operated in the sphygmomanometer 1, the circumference information is obtained by the process of steps S201 to S205 instead of the above step S101. May be obtained. Specifically, in step S201, the CPU 40 outputs a control signal for driving the pump 21 at a predetermined voltage that is specified in advance to the pump driving circuit 26, and the pump 21 is driven at a predetermined voltage so that the fluid bag 13 is The fluid bag 13 is pressurized until it reaches a prescribed predetermined pressure. When the predetermined pressure is reached (YES in step S203), the CPU 40 stores the pressurization time until the fluid bag 13 reaches the predetermined pressure in step S205. As shown in FIG. 4A, when the drive voltage for driving the pump 21 is the same, the pressurization speed decreases as the circumference of the measurement region increases. Therefore, as shown in FIG. 4B, the pressurization time increases as the circumference of the measurement site increases. That is, it can be said that the pressurization time until the fluid bag 13 reaches a predetermined pressure is an index representing the circumference of the measurement site. Therefore, the circumference information acquisition unit 41 acquires the pressurization time stored in step S205 as circumference information. In addition, the circumference information acquisition part 41 is obtained similarly from the rotation speed of the pump 21 and the pressure of the fluid bag 13 instead of the pressurization time. As another example, a cloth (not shown) as a means for winding the fluid bag 13 around the measurement site includes slide resistance, and the circumference information acquisition unit 41 winds the fluid bag 13 around the measurement site. The circumference information may be acquired from the resistance value obtained from the above slide resistance.

  In steps S103 and S105, the CPU 40 outputs a control signal to the pump drive circuit 26, and pressurizes the fluid bag 13 until the fluid bag 13 reaches a predetermined pressure. When the predetermined pressure is reached (YES in step S105), the CPU 40 outputs a control signal to the pump drive circuit 26 in step S107 and stops pressurization of the fluid bag 13. Thereafter, in step S109, the valve drive voltage determination unit 43 of the CPU 40 determines the drive voltage E of the valve 22 based on the circumference information acquired in step S101 or steps S201 to S205. In step S111, the CPU 40 outputs a control signal to the valve drive circuit 27 so as to drive the valve 22 while maintaining the drive voltage E determined in step S109, and starts depressurization of the fluid bag 13. In step S113, the CPU 40 extracts a vibration component accompanying the arterial volume change superimposed on the internal pressure of the fluid bag 13 obtained during decompression, and calculates a blood pressure value by a predetermined calculation. It should be noted that when the pressure reduction rate in step S111 is too fast and the blood pressure value is not calculated in step S113, or conversely, when the pressure reduction rate in step S111 is too slow and the discharge does not proceed (NO in step S114). In step S117, the CPU 40 determines that an error has occurred, and outputs a control signal to the valve drive circuit 27 so as to open the valve 22. The fluid in the fluid bag 13 is rapidly discharged. If not, that is, if the blood pressure value is calculated in step S113 (YES in step S114), the valve 22 is opened in accordance with the control signal from the CPU 40 in step S115, and the fluid in the fluid bag 13 is discharged. .

  The determination of the drive voltage E in the valve drive voltage determination unit 43 in step S109 will be described.

  Here, as shown in FIG. 5, the degree of change in the pressure reduction rate relative to the pressure of the fluid bag when the driving voltage E is kept constant varies depending on the circumference of the measurement site. Specifically, referring to FIG. 5, the smaller the circumference of the measurement site, the greater the degree of change in the decompression speed, and the greater the circumference of the measurement site, the smaller the degree of change in the decompression speed. That is, from the relationship shown in FIG. 5, it can be said that the circumference of the measurement site is a parameter for determining the drive voltage E.

In step S109, the valve drive voltage determination unit 43 determines the drive voltage E using the relationship shown in FIG. As a specific example, the valve drive voltage determination unit 43 determines the drive voltage E by substituting the circumference information acquired in step S101 or steps S201 to S205 into the following equation (1):
Drive voltage E = α × peripheral length information + β (1)

  By using the above-described equation (1) in step S109, as shown in FIG. 6, the drive voltage E is determined with a magnitude proportional to the circumference of the measurement site.

  Here, when the circumference of the measurement site is the same, the degree of change in the pressure reduction rate with respect to the pressure of the fluid bag 13 varies depending on the gap of the valve 22, that is, the magnitude of the drive voltage, as shown in FIG. Specifically, referring to FIG. 7, the degree of change in pressure reduction rate increases as the gap of valve 22 increases, and the degree of change in pressure reduction rate decreases as the gap decreases. Therefore, from the relationship shown in FIG. 7, the size of the gap is preferably such that the decompression speed of the fluid bag 13 from the calculation of the maximum blood pressure to the calculation of the minimum blood pressure is within a predetermined speed range. . More specifically, the size of the gap is preferably the size of the gap at which the rate of pressure reduction is such that the pulse rate that can be detected between the systolic blood pressure and the systolic blood pressure during decompression is equal to or greater than a predetermined number. More preferably, the “predetermined number” is 5. This is because a pulse rate of about 5 is measured between the systolic blood pressure and the diastolic blood pressure at the time of decompression, as described in Japanese Patent No. 3179873 previously filed and disclosed by the applicant of the present application. This is because it is appropriate to set the pressure reduction measurement algorithm in consideration of the performance of the pressure reduction measurement algorithm. It is assumed that the gap size at which a pulse rate of 5 or more is measured between the systolic blood pressure and the systolic blood pressure during decompression is obtained by, for example, experiments and stored in the memory 6 in advance. Specifically, the value is preferably about 3 mmHg / sec to 13 mmHg / sec. Accordingly, the coefficients α and β in the above equation (1) are set so that the blood pressure reduction rate in the range where the pressure of the fluid bag 13 is about the blood pressure value is within a target pressure reduction rate of about 3 mmHg / sec to 13 mmHg / sec. It can be set to any value. Such coefficients α and β are obtained in advance by experiments or the like and are stored in the memory 6 of the sphygmomanometer 1. In the above example, it is assumed that the drive voltage E is determined by inputting the circumference information acquired in the above equation (1) in step S109. However, instead of the equation (1), the memory 6 has a circumference. A table that defines the relationship between the information and the drive voltage E may be stored, and the valve drive voltage determination unit 43 may read the drive voltage E corresponding to the acquired circumference information from the table.

[Modification]
FIG. 8 is a flowchart showing a modification of the process executed at the timing when the measurement switch 32 is operated in the sphygmomanometer 1. In the process shown in FIG. 8, as in the second specific example shown in FIG. 3, based on the pressurization time until the pressure of the fluid bag 13 reaches a predetermined pressure in steps S <b> 201 to S <b> 205, While the circumference is estimated, in the subsequent pressurization process, in step S301, the CPU 40 estimates the maximum blood pressure value based on the change in the internal pressure of the fluid bag 13 obtained from the pressure sensor 23, and in step S303, the fluid bag 13 The pressure at the end of pressurization is calculated. The sphygmomanometer 1 is configured to calculate a blood pressure value based on a change in the internal pressure of the fluid bag 13 obtained in a pressure reducing process after pressurizing the fluid bag 13 to a predetermined pressure. Therefore, in step S303, preferably, the CPU 40 calculates a pressure value that is higher by a predetermined pressure value than the maximum blood pressure value estimated in step S301 as the pressurization end pressure. When the pressure of the fluid bag 13 reaches the pressurization end pressure calculated in step S303 (YES in step S105 ′), the drive voltage E is determined in the same manner as the processing shown in FIG. 2 and FIG. The blood pressure value is calculated in the decompression process in which control is performed to drive the valve while holding the drive voltage E.

In the modified example, in step S109, the valve drive voltage determination unit 43 replaces or adds to the relationship shown in FIG. 5 described above, or considers the drive voltage in consideration of the maximum blood pressure value estimated in step S301. E is determined. As a specific example, the drive voltage determination unit 43 determines the drive voltage E by substituting the circumference information acquired in step 101 or steps S201 to S205 into the following equation (2):
Drive voltage E = α × circumference information + β + offset amount S,
Offset amount S = estimated systolic blood pressure value × γ Expression (2).

  By using the above-described equation (2) in step S109 in the modification, as shown in FIG. 9, the drive voltage E has a magnitude proportional to the circumference of the measurement site and the estimated maximum blood pressure. It is determined by the corresponding size.

  From the relationship described with reference to FIG. 7, the size of the gap is preferably such that the pressure of the fluid bag 13 is within the target decompression speed within the range where the pressure of the fluid bag 13 is about the blood pressure value. Accordingly, the coefficient γ in the above equation (2) also sets the pressure reduction speed from the calculation of the maximum blood pressure to the calculation of the minimum blood pressure within the fluid bag 13 within the target pressure reduction speed of about 3 mmHg / sec to 13 mmHg / sec. It can be set to such a value.

  In step S111, the CPU 40 controls to drive the valve 22 while maintaining the drive voltage E determined in step S109. In other words, the gap of the valve 22 is controlled to be constant during decompression. Thereby, at the time of decompression, the decompression speed of the fluid bag 13 changes as shown in FIG. That is, from FIG. 10 (A), when the pressure of the fluid bag 13 becomes a certain pressure or less, the pressure reducing speed of the fluid bag 13 is substantially the same value regardless of the circumference of the measurement site. (Decrease) Almost no change due to pressure change. Further, at the time of depressurization, the discharge amount from the valve 22 at the pressure of the fluid bag 13 changes as shown in FIG. That is, from FIG. 10B, when the pressure of the fluid bag 13 becomes a certain pressure or less, the discharge amount from the valve 22 is a value corresponding to the circumference of the measurement site, and the subsequent (decrease) pressure change. Almost no change. That is, from the relationship shown in FIGS. 10A and 10B, controlling the drive voltage E to be constant, that is, controlling the gap of the valve 22 to be constant, means that the valve 22 It can be said that the drive voltage E is controlled so that the discharge amount from the fluid and the pressure reduction speed of the fluid bag 13 are in a proportional relationship.

  By controlling the CPU 40 in this way, in the sphygmomanometer 1, the flow rate of the fluid exiting the fluid bag 13 and the pressure reduction speed can be brought close to a proportional relationship. Thereby, the detection accuracy of the volume change of the blood vessel can be made almost constant, and the measurement accuracy can be improved. That is, as shown in FIG. 10C, the pressure pulse wave amplitude with respect to a constant volume change can be made constant with a value corresponding to the circumference of the measurement site, regardless of the pressure change of the fluid bag 13.

  FIG. 11 is a diagram for explaining the relationship between the pressure of the fluid bag 13 and the detected pulse wave amplitude. FIG. 11A shows the pressure change of the fluid bag 13 over time and the pressure change of the intra-arterial pressure. A dotted line A in FIG. 11A shows a change in pressure of the fluid bag 13 when the pressure of the fluid bag is controlled to be reduced at a constant speed. On the other hand, in the sphygmomanometer 1 according to the present embodiment, the change in pressure of the fluid bag 13 when the drive voltage E is constant, that is, when the pressure is reduced so that the gap of the valve 22 is constant is indicated by a solid line B. ing. In the sphygmomanometer 1, the pressure is reduced by controlling the driving voltage E to be constant, that is, the gap of the valve 22 is constant, so that the pressure change (decompression) of the fluid bag 13 is conventionally shown in FIG. Is measured as shown in FIG. 11C. Specifically, in FIG. 11C, a line segment obtained by connecting the measured values of the intra-arterial pressure shown in FIG. 11B is indicated by a dotted line. In the conventional sphygmomanometer controlled to reduce the pressure of the fluid bag at a constant speed, as shown in FIGS. 16 and 17, even if the pressure in the artery is the same, the pressure in the region where the pressure of the fluid bag is low is high. Compared with the region, the detection accuracy of the volume change of the blood vessel is lowered. On the other hand, in the sphygmomanometer 1 according to the present embodiment, as shown by comparing FIG. 11B and FIG. 11C, the volume change of the blood vessel in the low pressure region of the fluid bag 13 It is clearly shown that the detection accuracy is improved over the detection accuracy of a conventional sphygmomanometer controlled to reduce the pressure of the fluid bag at a constant speed. Similarly, it is shown that the detection accuracy of the volume change of the blood vessel in the high pressure region is also improved.

  In the above example, the CPU 40 holds the drive voltage E at the drive voltage E determined by the valve drive voltage determination unit 43 at the step S109 in the decompression process at the step S111, that is, keeps the drive voltage E constant. Control to keep. However, in addition to the configuration shown above, the sphygmomanometer 1 further includes a flow meter 55 for measuring the discharge amount from the valve 22, as shown in FIG. The drive voltage E may be updated by 43 so that the discharge amount from the valve 22 and the pressure reduction speed are in a proportional relationship. In this case, the CPU 40 performs feedback control to control the drive voltage E so that the drive voltage E is changed to the drive voltage E determined at a specific timing such as a predetermined time interval. By performing such feedback control, the flow rate of the fluid coming out of the fluid bag 13 and the pressure reduction speed can be brought closer to a proportional relationship. Thereby, the pressure pulse wave amplitude with respect to a constant blood vessel volume change can be made to be constant, and the measurement accuracy can be improved.

[Second Embodiment]
FIG. 12 is a block diagram showing a specific example of the hardware configuration of a sphygmomanometer 1 ′ which is a blood pressure measurement device according to the second embodiment of the present invention. Referring to FIG. 12, sphygmomanometer 1 ′ is an incompressible type connected to fluid bag 13 by tube 10 in addition to the hardware configuration of sphygmomanometer 1 of the first embodiment shown in FIG. 1. A tank 54 for storing fluid is further provided. The tank 54 is connected to the pump 51 and the valve 52. Pump 51 and valve 52 are connected to pump drive circuit 56 and valve drive circuit 57, respectively. Pump drive circuit 56 and valve drive circuit 57 are each connected to CPU 40. The CPU 40 determines a voltage for driving the pump 51 and the valve 52 by executing a predetermined program stored in the memory 6 based on the operation signal input from the operation unit 3, and the pump drive circuit 56. And the control signal according to the determined voltage is output to the valve drive circuit 57. When the pump 51 is driven, the incompressible fluid stored in the tank 54 flows into the fluid bag 13 through the tube 10. By driving the valve 52, the incompressible fluid in the fluid bag 13 is discharged.

  A filter 9 is provided at a portion connecting the fluid bag 13 and the valve 22. When the incompressible fluid in the tank 54 moves to the fluid bag 13, the incompressible fluid is prevented from leaking from the valve 22 for injecting the fluid into the fluid bag 13 or discharging the fluid from the fluid bag 13. Therefore, the material of the filter 9 is preferably a material that allows fluid to permeate but does not allow incompressible fluid to permeate.

  FIG. 13 is a flowchart showing a specific example of processing executed at the timing when the measurement switch 32 is operated in the sphygmomanometer 1 '. The processing shown in the flowchart of FIG. 13 is realized by the CPU 40 executing a predetermined program stored in the memory 6.

  With reference to FIG. 13, in the sphygmomanometer 1 ′ according to the second embodiment, in step S <b> 401, the CPU 40 outputs a control signal to the valve drive circuit 27 to close the valve 22, and the fluid to the fluid bag 13 is blocked. Block the inlet and outlet. Thereafter, in step S403, a control signal is output to the pump drive circuit 56 to drive the pump 51, and the tank 54 is filled until the fluid bag 13 reaches a predetermined pressure defined in advance or reaches a predetermined pressurization speed. The incompressible fluid is caused to flow into the fluid bag 13. That is, the incompressible fluid is moved from the tank 54 to the fluid bag 13. When the internal pressure of the fluid bag 13 reaches a predetermined pressure, or when the pressurization speed of the fluid bag 13 reaches a predetermined pressurization speed (YES in step S405), the CPU 40 sends a control signal to the valve drive circuit 57 in step S407. The output valve 52 is closed, and the inlet of the incompressible fluid to the fluid bag 13 is blocked. After the blockage, the CPU 40 outputs a control signal to the valve drive circuit 27 to open the valve 22 and release the pressure in the fluid bag 13 in step S409. As a result, a predetermined amount of incompressible fluid is injected into the fluid bag 13, and the internal pressure is atmospheric pressure.

  Thereafter, processing similar to the processing according to the first embodiment is performed, and the processing of steps S103 to S107 is performed. The fluid bag 13 is pressurized until the fluid bag 13 reaches a predetermined pressure, and the processing is performed. In this state, pressurization of the fluid bag 13 is stopped. Thereafter, the blood pressure value is calculated in step S113 while the fluid bag 13 is decompressed in step S111.

  In the sphygmomanometer 1 ′ according to the second embodiment, when the calculation of the blood pressure value is completed (YES in step S411), in step S413, the CPU 40 outputs a control signal to the valve drive circuit 57 to open the valve 52, and fluid The incompressible fluid in the bag 13 is discharged. Thereafter, in step S115, the valve 22 is opened according to the control signal from the CPU 40, and the fluid in the fluid bag 13 is discharged.

  Prior to pressurization of the fluid bag 13 in step S103, the sphygmomanometer 1 ′ according to the second embodiment injects a predetermined amount of incompressible fluid into the fluid bag 13 to increase the volume of the fluid bag 13. The volume is increased, and the volume of the fluid flowing in is reduced. As a result, compared to the method of injecting all the fluid from the initial state, as described above with reference to FIG. 15, in the region where the internal pressure of the fluid bag 13 is low, which is indicated by the portion A in FIG. 15. The volume change of the fluid bag 13 is suppressed. For this reason, in the sphygmomanometer 1 ′, it is possible to improve the detection accuracy of the blood vessel volume change.

  In the above example, the incompressible fluid flows into the fluid bag 13 as means for suppressing the volume change of the volume change of the fluid bag 13 in the low pressure region. However, as another specific example of the above means, the fluid bag A filling member may be arranged in advance 13. For example, as shown in FIG. 14 (A), a method in which a gel material such as microbeads is previously introduced into the fluid bag 13 as a filling member may be used. Further, for example, as shown in FIGS. 14B and 14C, an elastic material such as a sponge or a spring may be disposed in the fluid bag 13 in advance as a filling member. By arranging these filling members in the fluid bag 13 in advance, the volume of the fluid bag 13 can be increased before pressurization. The filling member is not limited to the above-described gel material or elastic material, and may be other materials. The filling member may be a combination of these plural materials.

  Furthermore, you may combine the control at the time of pressure reduction concerning 1st Embodiment, and the structure concerning 2nd Embodiment. That is, after the pressurization of the fluid bag 13 is stopped in step S107 in the process in the sphygmomanometer 1 ′, the process in step S109 may be performed to control and reduce the pressure so that the gap of the valve 22 becomes constant. . By doing so, the flow rate of the fluid exiting the fluid bag 13 and the pressure reduction speed can be made closer to a proportional relationship. Thereby, the detection accuracy of the volume change of the blood vessel can be made almost constant, and the measurement accuracy can be improved.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a block diagram which shows the specific example of the hardware constitutions of the blood pressure meter which is the blood pressure measuring device concerning the 1st Embodiment of this invention. It is a flowchart which shows the 1st specific example of the process performed at the timing when the measurement switch was operated in the blood pressure meter concerning the 1st Embodiment of this invention. It is a flowchart which shows the 2nd specific example of the process performed at the timing when the measurement switch was operated in the blood pressure meter concerning the 1st Embodiment of this invention. It is a figure which shows the relationship (A) of the circumference of a measurement site | part, and a pressurization speed, and the relationship (B) of the circumference of a measurement site | part, and a pressurization time. It is a figure which shows the change degree of the pressure reduction speed with respect to the pressure of the fluid bag at the time of hold | maintaining the valve drive voltage constant for every circumference of a measurement region. It is a figure which shows the relationship between the drive voltage of a valve and the circumference of a measurement site | part determined in the blood pressure meter concerning the 1st Embodiment of this invention. It is a figure which shows the change degree of the pressure reduction speed with respect to the pressure of the fluid bag in case the circumference of a measurement site | part is the same for every gap of a valve. It is a flowchart which shows the modification of the process performed at the timing when the measurement switch was operated in the blood pressure meter concerning the 1st Embodiment of this invention. It is a figure which shows the relationship between the drive voltage of a valve determined by the blood pressure meter concerning the modification of the 1st Embodiment of this invention, and the circumference of a measurement site | part. In the sphygmomanometer according to the first embodiment of the present invention, the relationship (A) between the pressure of the fluid bag and the pressure reduction rate, the relationship (B) between the pressure of the fluid bag and the fluid discharge amount, and the pressure of the fluid bag It is a figure which shows the relationship (C) with the pressure pulse wave amplitude value with respect to a fixed volume change. It is a figure for demonstrating the relationship between the pressure of a fluid bag, and the detected pulse wave amplitude. It is a block diagram which shows the specific example of the hardware constitutions of the blood pressure meter which is the blood pressure measuring device concerning the 2nd Embodiment of this invention. It is a flowchart which shows the specific example of the process performed at the timing when the measurement switch was operated in the blood pressure meter concerning the 2nd Embodiment of this invention. It is a figure which shows the other specific example of a structure of the blood pressure meter concerning the 2nd Embodiment of this invention. It is a figure explaining the characteristic of a fluid bag. It is a figure showing the volume change of the fluid bag, the change of the fluid density in the fluid bag, and the pressure change of the fluid bag accompanying the change of the volume of the blood vessel when the fluid density in the fluid bag is low. It is a figure showing the volume change of the fluid bag, the change of the fluid density in the fluid bag, and the pressure change of the fluid bag with the change of the volume of the blood vessel when the fluid density in the fluid bag is high. It is a figure showing the volume change of the fluid bag accompanying the volume change of the blood vessel, and the pressure change of the fluid bag when the discharge speed of the fluid exiting from the fluid bag is fast, that is, when the discharge amount per unit time is large. It is a figure showing the volume change of the fluid bag accompanying the volume change of the blood vessel, and the pressure change of the fluid bag when the discharge speed of the fluid exiting from the fluid bag is slow, that is, when the discharge amount per unit time is small. In a sphygmomanometer that depressurizes the fluid bag at a constant speed, the relationship between the pressure of the fluid bag and the decompression speed (A), the relationship between the pressure of the fluid bag and the amount of fluid discharged (B), and the pressure of the fluid bag and the constant It is a figure which shows the relationship (C) with the pressure pulse wave amplitude value with respect to the volume change. It is a block diagram which shows the other specific example of the hardware constitutions of the blood pressure meter which is the blood pressure measurement apparatus concerning the 1st Embodiment of this invention.

Explanation of symbols

  1, 1 'sphygmomanometer, 2 main body, 3 operation section, 4 display section, 5 cuff, 6, 7 memory, 9 filter, 10 tube, 13 fluid bag, 31 power switch, 21 pump, 22 valve, 23 pressure sensor, 26 pump drive circuit, 27 valve drive circuit, 28 oscillation circuit, 32 measurement switch, 33 stop switch, 34 record call switch, 40 CPU, 41 circumference information acquisition unit, 43 valve drive voltage determination unit, 51 pump, 52 valve, 53 power supply, 54 tank, 55 flow meter, 56 pump drive circuit, 57 valve drive circuit.

Claims (18)

A fluid bag;
Pressurizing means for injecting and pressurizing fluid into the fluid bag;
Pressure reducing means for discharging the fluid from the fluid bag and reducing the pressure;
A sensor for measuring a change in internal pressure of the fluid bag;
A blood pressure measuring means for calculating a blood pressure value based on a change in internal pressure of the fluid bag obtained by the sensor in a pressure reducing process for discharging the fluid from the fluid bag by the pressure reducing means;
Control means for controlling the pressurizing means, the pressure reducing means, and the blood pressure measuring means,
The control means determines a control amount for controlling the fluid discharge amount in the pressure reducing means so that the fluid discharge amount per unit time in the pressure reduction process is proportional to the pressure reduction speed of the fluid bag. And a blood pressure measuring device for controlling the discharge amount. The pressure reducing means includes a valve provided in the fluid bag,
The controlled variable is the valve gap;
The blood pressure measurement device according to claim 1, wherein the control means controls the discharge amount by controlling the gap of the valve to be held in the determined gap in the decompression process.   The control means determines the gap of the valve, which is the control amount, so that a pressure reduction rate including a predetermined number of pulses or more is included in a time when the internal pressure of the fluid bag changes from the highest blood pressure to the lowest blood pressure. The blood pressure measurement device according to claim 2. The control means includes acquisition means for acquiring information related to the circumference of the measurement site,
The blood pressure measurement device according to claim 2 or 3, wherein the control means determines the gap of the valve, which is the control amount, according to the circumference. It further comprises input means for inputting the circumference,
The blood pressure measurement device according to claim 4, wherein the acquisition unit acquires information related to the circumference by input from the input unit. The blood pressure measurement device according to claim 4, wherein the acquisition unit acquires information about the circumference based on a pressurization time in the pressurization unit until an internal pressure of the fluid bag becomes a predetermined pressure. The pressurizing means includes a pump;
The blood pressure measurement device according to claim 4, wherein the acquisition unit acquires information related to the circumference based on a rotation speed of the pump and an internal pressure of the fluid bag. A winding means for winding the fluid bag around the measurement site;
The winding means includes a slide resistance,
The blood pressure measurement device according to claim 4, wherein the acquisition unit acquires information on the circumference based on a resistance value obtained from the slide resistance by winding the fluid bag around the measurement site by the winding unit. . The blood pressure measuring means further calculates a blood pressure value based on a change in internal pressure of the fluid bag obtained by the sensor in a pressurizing process in which a fluid is injected into the fluid bag by the pressurizing means,
The said control means determines the gap of the said valve which is the said control amount according to the said blood pressure value calculated based on the internal pressure change of the said fluid bag in the said pressurization process, In any one of Claims 2-8 The blood pressure measurement device described. The blood pressure measuring means further calculates a period of a pulse wave based on a change in internal pressure of the fluid bag obtained by the sensor in a pressurizing process in which a fluid is injected into the fluid bag by the pressurizing means,
The blood pressure measurement according to any one of claims 2 to 8, wherein the control means determines a gap of the valve according to a cycle of a pulse wave calculated based on a change in internal pressure of the fluid bag in the pressurizing process. apparatus. Further comprising a measuring means for measuring the emission amount,
Based on the discharge amount measured by the measurement means and the change in the internal pressure of the fluid bag obtained by the sensor, the control means determines the amount of fluid discharged per unit time in the decompression process. The blood pressure measurement device according to claim 1 or 2, wherein the fluid discharge amount by the pressure reducing means is controlled so as to be proportional to a pressure reduction speed. Further comprising increasing means for increasing the volume of the fluid bag;
The blood pressure measurement device according to any one of claims 1 to 11, wherein the pressurizing unit injects and pressurizes the fluid into the fluid bag whose volume is increased by the increasing unit. The increasing means includes injecting means for injecting an incompressible fluid into the fluid bag;
The blood pressure measurement according to claim 12, wherein the control means controls the injecting means to inject the incompressible fluid into the fluid bag before injecting the fluid into the fluid bag with the pressurizing means. apparatus.   The control means controls the injection means to inject a predetermined amount of the incompressible fluid into the fluid bag before injecting the fluid into the fluid bag with the pressurizing means. Blood pressure measuring device. The control means includes
The injecting means before injecting fluid into the fluid bag with the pressurizing means until the pressure of the fluid bag reaches a predetermined pressure or until the pressurizing speed of the fluid bag reaches a predetermined pressurizing speed. Injecting said incompressible fluid into said fluid bag;
Releasing the pressure of the fluid bag to atmospheric pressure after the pressure of the fluid bag reaches a predetermined pressure, or after the pressurization speed of the fluid bag reaches a predetermined pressurization speed;
The blood pressure measurement according to claim 13 or 14, wherein after the pressure of the fluid bag is set to atmospheric pressure, the control is performed including closing the fluid bag and starting injection of the fluid by the pressurizing means. apparatus.   The part which connects the said fluid bag and the discharge port for discharging | emitting the fluid with the said pressure reduction means is equipped with the filter which the said fluid permeate | transmits and the said incompressible fluid does not permeate | transmit. The blood pressure measurement device described in 1.   The blood pressure measurement device according to claim 12, wherein the increasing means is a filling member disposed in the fluid bag.   The blood pressure measurement device according to claim 17, wherein the filling member includes any one of a sponge, a spring, and microbeads.

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