Blood pressure measurement device and control method

Abstract

To provide a blood pressure measuring device and a control method capable of raising the pressure of a cuff wound around a subject at a target pressure raising speed at an initial stage after measurement of the subject's blood pressure is started.SOLUTION: A blood pressure measuring device measures blood pressure of a subject while the pressure in a cuff wound around a subject is raised in a blood pressure measurement range. The blood pressure measuring device includes: a pressure raising part for executing a pressure raising operation for raising the pressure in the cuff; a calculation part for calculating a pressure raising speed in the cuff before the actual pressure in the cuff is brought into the blood pressure measurement range; and a control part for controlling the pressure raising operation with a predetermined amount of control according to the calculated pressure raising speed so that the actual pressure raising speed in the cuff is converged to a target pressure raising speed when the actual pressure in the cuff is brought into the blood pressure measurement range.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a blood pressure measuring device and a control method.

Background Art

[0002] In recent years, blood pressure measuring devices capable of automatically measuring blood pressure have been widely spread in general households and public places and are used as part of health management. Thus, various blood pressure measuring devices have been proposed as devices that can be easily used not only by medical institutions but also by ordinary people.

[0003] As a method of measuring blood pressure by a blood pressure measuring device, for example, after the pressure in a cuff wound around a blood pressure measurement site of a subject is increased to a pressure higher than the systolic blood pressure (SYS) by a pump or the like, in the process of decreasing the pressure at a constant speed of exhaust (for example, 3 to 5 mmHg / second), blood pressure (for example, maximum blood pressure, minimum blood pressure) is measured based on a pulse wave signal superimposed on a sensor detection signal (pressure signal) obtained by a pressure sensor. A descending pressure measurement method is used (see, for example, Patent Document 1).

[0004] In addition, an ascending pressure measurement method is used for the purpose of reducing the burden on the blood pressure measurement site by shortening the blood pressure measurement time compared with the descending pressure measurement method. In this ascending pressure measurement method, the blood pressure of a subject is measured based on a pulse wave signal superimposed on a sensor detection signal obtained by a pressure sensor in the process of increasing the pressure in the cuff to, for example, 160 to 190 mmHg.

[0005] In both the descending pressure measurement method and the ascending pressure measurement method, a volume change due to blood flow in a blood vessel in the cuff is detected as an amplitude change of the pressure in the cuff, and blood pressure is measured based on the detected amplitude change. Note that the amount of amplitude change of the pressure in the cuff varies depending on the blood pressure value, the volume of the cuff, the blood flow of the subject, etc., and is about 1 / 10 mmHg when it is small.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-136491 [Summary of the Invention] [Problems to be Solved by the Invention]

[0007] By the way, in the step-up measurement method, even if there is a difference in the ease of inflation of the cuff due to the size (volume) of the cuff wound around the blood pressure measurement site of the subject or the difference in the way the cuff is wound, in order to accurately measure the blood pressure of the subject by acquiring a correct pulse wave signal, it is necessary to increase the pressure in the cuff at a predetermined target pressure increase rate (the amount of pressure increase per unit time). Therefore, conventionally, feedback control has been performed to control the pressure increase operation of the pressure in the cuff according to the difference between the actual pressure increase rate of the cuff and the target pressure increase rate.

[0008] However, generally, there is a response delay for the control signal in feedback control, and the pressure increase rate in the cuff does not immediately change even when a control signal is output. Further, considering the response delay and increasing the control amount so that the actual pressure increase rate of the cuff converges to the target pressure increase rate in a short time, the actual pressure increase rate fluctuates greatly and goes above and below the target value, and as a result, fluctuations occur in the pulse wave signal superimposed on the sensor detection signal obtained in the process of increasing the pressure of the cuff. As a result, it becomes difficult to accurately measure the blood pressure of the subject by acquiring a correct pulse wave signal.

[0009] Therefore, it is conceivable to reduce the control amount in order to suppress the occurrence of fluctuations in the pulse wave signal superimposed on the sensor detection signal obtained in the process of increasing the pressure of the cuff. However, in this case, there is a problem that the time until the actual pressure increase rate of the cuff converges to the target pressure increase rate becomes long, and it becomes difficult to increase the pressure at the target pressure increase rate in the initial stage after the start of blood pressure measurement of the subject. In particular, if the actual pressure increase rate of the cuff does not converge to the target pressure increase rate when the actual pressure in the cuff is low, it is impossible to sufficiently acquire the correct pulse wave signal of the subject, and it is impossible to measure the minimum blood pressure of the subject at all or to accurately measure the minimum blood pressure.

[0010] An object of the present invention is to provide a blood pressure measurement device and a control method capable of increasing the pressure of a cuff wound around a subject at a target pressure increase rate in an initial stage after the start of blood pressure measurement of the subject. **Means for Solving the Problems**

[0011] The blood pressure measurement device according to the present invention is a blood pressure measurement device that performs blood pressure measurement of the subject while increasing the pressure in a cuff wound around the subject within a blood pressure measurement range, a pressure increasing unit that performs a pressure increasing operation for increasing the pressure in the cuff, a calculation unit that calculates a pressure increase rate in the cuff before the pressure in the cuff enters the blood pressure measurement range, a control unit that controls the pressure increasing operation with a predetermined control amount according to the calculated pressure increase rate so that the pressure increase rate in the cuff converges to a target pressure increase rate when the actual pressure in the cuff enters the blood pressure measurement range, and includes.

[0012] The control method according to the present invention is a control method in a blood pressure measurement device that performs blood pressure measurement of the subject while increasing the pressure in a cuff wound around the subject within a blood pressure measurement range, calculates a pressure increase rate in the cuff before the pressure in the cuff enters the blood pressure measurement range, and controls the pressure increasing operation with a predetermined control amount according to the calculated pressure increase rate so that the pressure increase rate in the cuff converges to a target pressure increase rate when the pressure in the cuff enters the blood pressure measurement range. **Advantages of the Invention**

[0013] According to the present invention, it is possible to increase the pressure of a cuff wound around a subject at a target pressure increase rate in an initial stage after the start of blood pressure measurement of the subject. **Brief Description of the Drawings**

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration example of a blood pressure measuring device 100 in the present embodiment. The blood pressure measuring device 100 is used, for example, in a medical facility such as a hospital to measure the blood pressure of a subject (for example, a patient). In the present embodiment, the blood pressure measuring device 100 uses a pressurization measurement method aimed at shortening the blood pressure measurement time and reducing the burden on the blood pressure measurement site compared to the decompression measurement method. That is, the blood pressure measuring device 100 pressurizes the pressure in the blood pressure measuring cuff 120 wound around the subject, and measures the blood pressure of the subject while the pressure is being pressurized within the blood pressure measurement range.

[0016] FIG. 2 is a diagram showing, by a solid line L, the time-series change of the pressure in the blood pressure measuring cuff 120 that is pressurized when the blood pressure of the subject is measured. As shown in FIG. 2, the blood pressure measuring device 100 measures the blood pressure of the subject based on the pulse wave signal superimposed on the sensor detection signal obtained by the pressure detection unit 106 that detects the pressure in the process of pressurizing the pressure (cuff pressure) in the blood pressure measuring cuff 120 to, for example, 160 mmHg. In the example shown in FIG. 2, the state where the pulse wave signal is superimposed on the sensor detection signal when the cuff pressure is, for example, 70 to 130 mmHg is shown.

[0017] As shown in FIG. 1, the blood pressure measurement device 100 includes a control unit 102, a booster unit 104, a pressure detection unit 106, a filter unit 108, a memory unit 110, an operation unit 112, and a display unit 114.

[0018] A blood pressure measurement cuff 120 (compression band) is connected to the blood pressure measurement device 100. The blood pressure measurement cuff 120 is configured longitudinally, for example, from a strip-shaped cloth bag containing an inflatable expansion bag made of synthetic rubber inside, and is configured to be wound around a blood pressure measurement site (for example, the upper arm) of the subject using fasteners provided on the inner side of the longitudinal end and the outer side of the intermediate portion in the longitudinal direction. Note that the blood pressure measurement cuff 120 functions as the "cuff" of the present invention.

[0019] The blood pressure measurement cuff 120 integrally includes a flexible tube (hose), and is connected to the booster unit 104 and the pressure detection unit 106 in the blood pressure measurement device 100 through a common air flow path by detachably inserting a connector provided at the tip of the flexible tube into a socket provided in the blood pressure measurement device 100.

[0020] The control unit 102 includes an arithmetic processing device such as a CPU (Central Processing Unit) and a memory device such as a RAM (Random Access Memory). The control unit 102 executes overall control of the blood pressure measurement device 100 by expanding a program stored in the memory unit 110 (for example, a ROM (Read Only Memory) or the like) into the memory device and executing it by the arithmetic processing device. Note that the control unit 102 functions as the "calculation unit" and the "control unit" of the present invention.

[0021] When the blood pressure of the subject is measured, the booster unit 104 boosts the pressure in the blood pressure measurement cuff 120 wound around the subject under the control of the control unit 102. In the present embodiment, the booster unit 104 includes an air supply unit 104A and an exhaust unit 104B.

[0022] The air supply unit 104A is a pump that supplies air to the blood pressure measurement cuff 120, that is, increases the pressure inside the blood pressure measurement cuff 120 by supplying air into the blood pressure measurement cuff 120. In the present embodiment, as the control of the air supply unit 104A, known Duty control based on the on-off time ratio of the air supply operation is adopted. That is, the air supply unit 104A changes the amount of air supplied to the blood pressure measurement cuff 120 according to the Duty ratio (for example, 0 to 100%) indicated by the Duty signal output from the control unit 102. The air supply unit 104A increases the amount of air supplied to the blood pressure measurement cuff 120 as the Duty ratio increases toward 100%, while decreasing the amount of air supplied to the blood pressure measurement cuff 120 as the Duty ratio decreases toward 0%.

[0023] The exhaust unit 104B is a flow control valve that exhausts air from the blood pressure measurement cuff 120, that is, reduces the pressure inside the blood pressure measurement cuff 120 by discharging the air inside the blood pressure measurement cuff 120. The flow control valve as the exhaust unit 104B can be realized by, for example, a solenoid-operated electromagnetic valve. In the present embodiment, as the control of the exhaust unit 104B, known Duty control based on the on-off time ratio of the exhaust operation is adopted. That is, the exhaust unit 104B changes the amount of exhaust air from the blood pressure measurement cuff 120 according to the Duty ratio (for example, 0 to 100%) indicated by the Duty signal output from the control unit 102. The exhaust unit 104B reduces the opening degree of the flow control valve and decreases the amount of exhaust air from the blood pressure measurement cuff 120 as the Duty ratio increases toward 100%, while increasing the opening degree of the flow control valve and increasing the amount of exhaust air from the blood pressure measurement cuff 120 as the Duty ratio decreases toward 0%.

[0024] As a result of air being supplied from the pressure boosting unit 104 to the blood pressure measurement cuff 120 according to the difference (= air supply amount - exhaust amount) between the air supply amount by the air supply unit 104A and the exhaust amount by the exhaust unit 104B, the pressure inside the blood pressure measurement cuff 120 increases.

[0025] The pressure detection unit 106 is a pressure - electrical conversion sensor using, for example, a piezo - element, etc. It detects the pressure inside the blood - pressure measurement cuff 120 and outputs a sensor output signal (electrical signal) indicating the detected pressure to the filter unit 108. Since the pressure inside the blood - pressure measurement cuff 120 changes due to the pulsation of the subject around whom the blood - pressure measurement cuff 120 is wound, a volume pulse wave signal component (hereinafter simply referred to as "pulse wave signal") is superimposed on the sensor output signal. The sensor output signal is sampled at a predetermined frequency by an AD converter (not shown) and converted into digital data.

[0026] The filter unit 108 extracts the pulse wave signal from the sensor output signal output from the pressure detection unit 106 and outputs the extracted pulse wave signal to the control unit 102. Specifically, the filter unit 108 can extract the pulse wave signal from the sensor output signal by using a band - pass filter that passes the frequency of a general pulse.

[0027] Also, the filter unit 108 generates a pressure signal from which the pump noise component (air supply unit 104A) and the pulse wave signal are removed from the sensor output signal output from the pressure detection unit 106 and outputs it to the control unit 102. Specifically, the filter unit 108 can generate a pressure signal by using a low - pass filter that removes AC components such as the pump noise component and the pulse wave signal from the sensor output signal.

[0028] When measuring the blood pressure of the subject, the control unit 102 controls the pressure - increasing operation of the pressure - increasing unit 104 (air supply unit 104A, exhaust unit 104B) based on the pressure signal output from the filter unit 108.

[0029] When measuring the blood pressure of the subject, the control unit 102 measures the blood - pressure value by applying a known algorithm based on the oscillometric method. The control unit 102 monitors the increase and decrease of the pulse - wave amplitude based on the transition of the pulse - wave amplitude obtained from the pressure signal and the pulse - wave signal output from the filter unit 108 and the pressure inside the blood - pressure measurement cuff 120, measures the cuff pressure at a predetermined timing during the increase of the pulse - wave amplitude as the minimum blood pressure, and measures the cuff pressure at a predetermined timing during the decrease of the pulse - wave amplitude as the maximum blood pressure.

[0030] After measuring the maximum blood pressure and the minimum blood pressure, the control unit 102 stores the values of the maximum blood pressure and the minimum blood pressure in the storage unit 110 as measurement data. After the blood pressure measurement of the subject is completed, the control unit 102 controls the pressure increasing unit 104 (the air supply unit 104A and the exhaust unit 104B) to stop the supply of air into the blood pressure measurement cuff 120 and discharge all the air in the blood pressure measurement cuff 120.

[0031] The storage unit 110 is a storage device that stores information related to the measurement data (such as the information of the subject) and the measurement data. The storage unit 110 may be configured to use a removable recording medium such as a memory card from the blood pressure measurement device 100.

[0032] The operation unit 112 is, for example, a key, a switch, a button, etc., and receives instructions and settings from the user. The operation unit 112 includes, for example, a power button / switch, a switch / button for instructing the start of blood pressure measurement, and a switch / button for instructing the cancellation of the ongoing blood pressure measurement. The control unit 102 monitors the operation of the operation unit 112 and executes an operation corresponding to the detected operation.

[0033] The display unit 114 is composed of, for example, a dot matrix display such as an LCD or an LED lamp, and displays the operating state, measurement results, guidance, etc. of the blood pressure measurement device 100 under the control of the control unit 102. Note that the blood pressure measurement device 100 may be provided with other output devices such as a speaker and a printer instead of or in addition to the display unit 114.

[0034] By the way, in the step-up measurement method used as the blood pressure measurement method by the blood pressure measurement device 100, even if there are differences in the ease of inflation (also referred to as compliance) of the blood pressure measurement cuff 120 due to differences in the size (volume) of the blood pressure measurement cuff 120 wound around the blood pressure measurement site of the subject and the way the blood pressure measurement cuff 120 is wound, in order to accurately measure the blood pressure of the subject by acquiring a correct pulse wave signal, it is necessary to increase the pressure of the blood pressure measurement cuff 120 at a predetermined target pressure increase rate (the amount of pressure increase per unit time). Therefore, conventionally, feedback control has been performed to control the pressure increase operation of the pressure in the blood pressure measurement cuff 120 according to the difference (deviation) between the actual pressure increase rate and the target pressure increase rate of the blood pressure measurement cuff 120.

[0035] However, generally, there is a response delay for the control signal in feedback control, and even if a control signal is output, the pressure increase rate in the blood pressure measurement cuff 120 does not immediately change. Also, considering the response delay and increasing the control amount so that the actual pressure increase rate in the blood pressure measurement cuff 120 converges to the target pressure increase rate in a short time, the actual pressure increase rate fluctuates greatly and crosses the target value, and as a result, fluctuations occur in the pulse wave signal superimposed on the sensor detection signal obtained in the process of increasing the pressure of the blood pressure measurement cuff 120. As a result, it becomes difficult to accurately measure the blood pressure of the subject by acquiring a correct pulse wave signal.

[0036] Therefore, it is conceivable to reduce the control amount in order to suppress the occurrence of fluctuations in the pulse wave signal superimposed on the sensor detection signal obtained in the process of increasing the pressure of the blood pressure measurement cuff 120. However, in this case, there is a problem that the time until the actual pressure increase rate in the blood pressure measurement cuff 120 converges to the target pressure increase rate becomes long, and it becomes difficult to increase the pressure at the target pressure increase rate in the initial stage after the start of blood pressure measurement of the subject. In particular, if the actual pressure increase rate in the blood pressure measurement cuff 120 does not converge to the target pressure increase rate when the actual pressure in the blood pressure measurement cuff 120 is low, it is impossible to sufficiently acquire the correct pulse wave signal of the subject, and it is impossible to measure the minimum blood pressure of the subject at all or to accurately measure the minimum blood pressure.

[0037] Therefore, in the present embodiment, the blood pressure measurement device 100 is configured to be able to increase the pressure of the blood pressure measurement cuff 120 wound around the subject at a target pressure increase rate at an initial stage after the start of blood pressure measurement of the subject.

[0038] Specifically, the control unit 102 of the blood pressure measurement device 100 calculates the pressure increase rate inside the blood pressure measurement cuff 120 before the actual pressure inside the blood pressure measurement cuff 120 enters the blood pressure measurement range based on the pressure signal output from the filter unit 108. Then, the control unit 102 controls the pressure increase operation of the pressure increase unit 104 with a predetermined control amount corresponding to the calculated pressure increase rate so that the pressure increase rate inside the blood pressure measurement cuff 120 converges to the target pressure increase rate when the actual pressure inside the blood pressure measurement cuff 120 enters the blood pressure measurement range.

[0039] The blood pressure measurement range is determined based on the blood pressure measurement performance of the blood pressure measurement device 100 and the like, and means a range in which the blood pressure of the subject with the blood pressure measurement cuff 120 wound around can be correctly measured. The target pressure increase rate is a pressure increase rate (for example, 5 to 10 mmHg / second) preset based on the blood pressure measurement performance of the blood pressure measurement device 100 and the like so that the blood pressure of the subject with the blood pressure measurement cuff 120 wound around can be correctly measured.

[0040] Next, with reference to the flowchart of FIG. 3, an example of the control operation of the blood pressure measurement device 100 (corresponding to the "control method" of the present invention) will be described. The process in step S100 is executed, for example, when an operation for instructing the start of blood pressure measurement is performed on the operation unit 112 in a state where the blood pressure measurement cuff 120 is wound around the blood pressure measurement site of the subject.

[0041] First, the control unit 102 controls the pressure boosting unit 104 to start a pressure boosting operation for boosting the pressure in the blood pressure measurement cuff 120 with a predetermined operation amount (step S100). In the present embodiment, the control unit 102 outputs a Duty signal indicating 100% as the Duty ratio to the air supply unit 104A, thereby causing the blood pressure measurement cuff 120 to be supplied with air at the maximum air supply amount. Further, the control unit 102 outputs a Duty signal indicating 100% as the Duty ratio to the exhaust unit 104B, thereby completely closing the flow control valve and preventing the blood pressure measurement cuff 120 from being exhausted. By starting the pressure boosting operation for boosting the pressure in the blood pressure measurement cuff 120 with a predetermined operation amount, the difference in the size (capacity) of the cuff wound around the blood pressure measurement site of the subject, and thus the difference in the ease of inflation of the cuff, appears as a difference in the pressure boosting speed in the blood pressure measurement cuff 120 at the initial stage after the start of the blood pressure measurement of the subject. Note that if the difference in the ease of inflation of the cuff clearly appears as a difference in the pressure boosting speed in the blood pressure measurement cuff 120, the control unit 102 does not necessarily have to supply air to the blood pressure measurement cuff 120 at the maximum air supply amount, and may output a Duty signal indicating, for example, 60% as the Duty ratio to the air supply unit 104A.

[0042] Next, the control unit 102 determines whether or not the actual pressure in the blood pressure measurement cuff 120 has reached a predetermined pressure before entering the blood pressure measurement range based on the pressure signal output from the filter unit 108 (step S120). As a result of the determination, if the actual pressure in the blood pressure measurement cuff 120 has not reached the predetermined pressure (step S120, NO), the process returns to before step S120. Note that the predetermined pressure is set, for example, to a value that is half of the lower limit value in the blood pressure measurement range.

[0043] On the other hand, when the actual pressure in the blood pressure measurement cuff 120 has reached the predetermined pressure (step S120, YES), the control unit 102 calculates the pressure boosting speed in the blood pressure measurement cuff 120 as the initial pressure boosting speed based on the pressure signal output from the filter unit 108 (step S140).

[0044] Next, the control unit 102 determines whether the initial pressure increase rate is equal to or higher than the first pressure increase rate (step S160). As a result of the determination, if the initial pressure increase rate is equal to or higher than the first pressure increase rate (step S160, YES), the control unit 102 controls the pressure increase operation of the pressure increase unit 104 with a predetermined first control amount so that the actual pressure increase rate in the blood pressure measurement cuff 120 converges to the target pressure increase rate when the actual pressure in the blood pressure measurement cuff 120 enters the blood pressure measurement range (step S180). Thereafter, the process transitions to step S240.

[0045] In the present embodiment, controlling the pressure increase operation of the pressure increase unit 104 with a predetermined first control amount means reducing the Duty ratio that defines the air supply amount of the air supply unit 104A by 40% from 100% to 60% and reducing the Duty ratio that defines the exhaust amount of the exhaust unit 104B by 50% from 100% to 50%. That is, the control unit 102 outputs a Duty signal indicating 60% as the Duty ratio to the air supply unit 104A to reduce the air supply amount to the blood pressure measurement cuff 120. Further, the control unit 102 outputs a Duty signal indicating 50% as the Duty ratio to the exhaust unit 104B to open the flow control valve halfway and cause the blood pressure measurement cuff 120 to exhaust. In this way, by performing abrupt control before the actual pressure in the blood pressure measurement cuff 120 enters the blood pressure measurement range, the actual pressure increase rate in the blood pressure measurement cuff 120 can be quickly brought closer to the target pressure increase rate. The predetermined first control amount is a control amount preset by conducting various experiments and simulations by changing the value of the initial pressure increase rate that is equal to or higher than the first pressure increase rate so that the actual pressure increase rate in the blood pressure measurement cuff 120 converges to the target pressure increase rate when the actual pressure in the blood pressure measurement cuff 120 enters the blood pressure measurement range.

[0046] Return to the determination process of step S160. When the initial pressure increase rate is smaller than the first pressure increase rate (step S160, NO), the control unit 102 determines whether the initial pressure increase rate is greater than the second pressure increase rate (step S200). As a result of the determination, when the initial pressure increase rate is greater than the second pressure increase rate (step S200, YES), the control unit 102 controls the pressure increase operation of the pressure increase unit 104 with a predetermined second control amount so that the actual pressure increase rate in the blood pressure measurement cuff 120 converges to the target pressure increase rate when the actual pressure in the blood pressure measurement cuff 120 enters the blood pressure measurement range (step S220). Then, the process transitions to step S240. Note that the first pressure increase rate and the second pressure increase rate correspond to the "plurality of predetermined pressure increase rates" of the present invention.

[0047] In the present embodiment, controlling the pressure increase operation of the pressure increase unit 104 with a predetermined second control amount means reducing the Duty ratio that defines the air supply amount of the air supply unit 104A by 10% from 100% to 90% and maintaining the Duty ratio that defines the exhaust amount of the exhaust unit 104B at 100%. That is, the control unit 102 outputs a Duty signal indicating 90% as the Duty ratio to the air supply unit 104A to reduce the air supply amount to the blood pressure measurement cuff 120. Further, the control unit 102 continues to output a Duty signal indicating 100% as the Duty ratio to the exhaust unit 104B so as not to exhaust the blood pressure measurement cuff 120 with the flow control valve completely closed. In this way, by performing relatively rapid control before the actual pressure in the blood pressure measurement cuff 120 enters the blood pressure measurement range, the actual pressure increase rate of the blood pressure measurement cuff 120 can be quickly brought closer to the target pressure increase rate. Note that the predetermined second control amount is a control amount set in advance by conducting various experiments and simulations by changing the values of the initial pressure increase rate that is smaller than the first pressure increase rate and greater than the second pressure increase rate so that the actual pressure increase rate in the blood pressure measurement cuff 120 converges to the target pressure increase rate when the actual pressure in the blood pressure measurement cuff 120 enters the blood pressure measurement range.

[0048] Return to the determination process in step S200. When the initial pressure increase rate is equal to or less than the second pressure increase rate (step S200, NO), the control unit 102 does not control the pressure increase operation of the pressure increasing unit 104 with a predetermined control amount. Since the actual pressure increase rate in the blood pressure measurement cuff 120 is relatively close to the target pressure increase rate, it is assumed that by controlling the pressure increasing unit 104 with the same predetermined operation amount, the actual pressure increase rate in the blood pressure measurement cuff 120 will converge to the target pressure increase rate when the actual pressure in the blood pressure measurement cuff 120 enters the blood pressure measurement range. As described above, the control unit 102 changes the combination of the air supply control amount in the air supply unit 104A and the exhaust control amount in the exhaust unit 104B based on the comparison results between the initial pressure increase rate, the first pressure increase rate, and the second pressure increase rate. Thereafter, the process transitions to step S240.

[0049] In step S240, the control unit 102 controls the pressure increase operation of the pressure increasing unit 104 according to the deviation between the actual pressure increase rate and the target pressure increase rate in the blood pressure measurement cuff 120 based on the pressure signal output from the filter unit 108. Specifically, the control unit 102 controls the air supply amount of the air supply unit 104A and the exhaust amount of the exhaust unit 104B so that the deviation between the actual pressure increase rate and the target pressure increase rate in the blood pressure measurement cuff 120 disappears. In this way, by performing gentle control so that the deviation between the actual pressure increase rate and the target pressure increase rate in the blood pressure measurement cuff 120 disappears, it is possible to converge the actual pressure increase rate to the target pressure increase rate while suppressing changes in the actual pressure increase rate as much as possible. As a result, while the actual pressure in the blood pressure measurement cuff 120 is increasing within the blood pressure measurement range, it is possible to accurately measure the blood pressure of the subject by acquiring the correct pulse wave signal superimposed on the sensor detection signal.

[0050] Then, the control unit 102 measures the blood pressure of the subject while the actual pressure in the blood pressure measurement cuff 120 is increasing within the blood pressure measurement range based on the pressure signal and the pulse wave signal output from the filter unit 108. Finally, the control unit 102 determines whether the blood pressure measurement process of the subject has ended (step S260).

[0051] If, as a result of the determination, the blood pressure measurement process for the subject has not been completed (step S260, NO), the process returns to before step S240. On the other hand, if the blood pressure measurement process for the subject has been completed (step S260, YES), the blood pressure measurement device 100 ends the process shown in FIG. 3.

[0052] In the control operation of the blood pressure measurement device 100 shown in FIG. 3, an example in which there are three patterns for controlling the pressurizing operation of the pressurizing unit 104 according to the calculated initial pressurizing speed has been described. However, there may be two patterns or four or more patterns. The main point is that the pressurizing operation of the pressurizing unit 104 is controlled according to the calculated initial pressurizing speed so that the actual pressurizing speed in the blood pressure measurement cuff 120 converges to the target pressurizing speed when the actual pressure in the blood pressure measurement cuff 120 enters the blood pressure measurement range.

[0053] Also, before the actual pressure in the blood pressure measurement cuff 120 reaches a predetermined pressure, instead of performing the pressurizing operation for increasing the pressure in the blood pressure measurement cuff 120 by a predetermined operation amount, the pressurizing operation of the pressurizing unit 104 may be controlled according to the deviation between the actual pressurizing speed and the target pressurizing speed in the blood pressure measurement cuff 120 as in the process of step S240.

[0054] FIG. 4 is a diagram showing the time-series change of the pressure in the blood pressure measurement cuff 120 when the control operation of the blood pressure measurement device 100 shown in FIG. 3 is executed and the pressure in the blood pressure measurement cuff 120 is increased at a low level. In FIG. 4, the solid line LA shows the time-series change of the pressure in the blood pressure measurement cuff 120 when the size of the blood pressure measurement cuff 120 wound around the blood pressure measurement site of the subject is smaller than normal and the blood pressure measurement cuff 120 is more likely to expand than normal. The dotted line LB shows the time-series change of the pressure in the blood pressure measurement cuff 120 when the size of the blood pressure measurement cuff 120 wound around the blood pressure measurement site of the subject is normal and the expandability of the blood pressure measurement cuff 120 is normal. The broken line LC shows the time-series change of the pressure in the blood pressure measurement cuff 120 when the size of the blood pressure measurement cuff 120 wound around the blood pressure measurement site of the subject is larger than normal and the blood pressure measurement cuff 120 is less likely to expand than normal.

[0055] The control unit 102 controls the booster unit 104 to start the boosting operation for increasing the pressure in the blood pressure measurement cuff 120 with a predetermined operation amount. Then, when the actual pressure in the blood pressure measurement cuff 120 reaches a predetermined pressure P1 before entering the blood pressure measurement range (indicated by reference numeral 220, the range where the pressure is P2 or higher), the control unit 102 calculates the initial boosting speed in the blood pressure measurement cuff 120.

[0056] Thereafter, when the initial boosting speed is equal to or higher than the first boosting speed (refer to the solid line LA), the control unit 102 controls the boosting operation of the booster unit 104 with a predetermined first control amount so that the actual boosting speed in the blood pressure measurement cuff 120 converges to the target boosting speed when the actual pressure in the blood pressure measurement cuff 120 enters the blood pressure measurement range 220. Also, when the initial boosting speed is smaller than the first boosting speed and larger than the second boosting speed (refer to the dotted line LB), the control unit 102 controls the boosting operation of the booster unit 104 with a predetermined second control amount so that the actual boosting speed in the blood pressure measurement cuff 120 converges to the target boosting speed when the actual pressure in the blood pressure measurement cuff 120 enters the blood pressure measurement range 220. Further, when the initial boosting speed is equal to or lower than the second boosting speed (refer to the broken line LC), the control unit 102 does not control the boosting operation of the booster unit 104 with a predetermined control amount.

[0057] Thereafter, the control unit 102 controls the boosting operation of the booster unit 104 according to the deviation between the actual boosting speed and the target boosting speed in the blood pressure measurement cuff 120. As shown by the solid line LA, the dotted line LB, and the broken line LC in FIG. 4, when the actual pressure in the blood pressure measurement cuff 120 enters the blood pressure measurement range 220, the actual boosting speed in the blood pressure measurement cuff 120 substantially converges to the target boosting speed. Thereby, even if the size of the blood pressure measurement cuff 120 wound around the blood pressure measurement site of the subject is particularly smaller or larger than normal, resulting in a difference in the ease of inflation of the blood pressure measurement cuff 120, at the initial stage after the start of blood pressure measurement of the subject, the blood pressure measurement cuff 120 can be stably boosted at the target boosting speed. As a result, a correct pulse wave signal can be sufficiently acquired at a stage where the actual pressure in the blood pressure measurement cuff 120 is low, and the minimum blood pressure of the subject can be accurately measured.

[0058] FIG. 5 is a diagram showing the time-series change of the pressure in the blood pressure measurement cuff 120 that is pressurized at a low stage of the actual pressure in the blood pressure measurement cuff 120 in the prior art where the control operation of the blood pressure measurement device 100 shown in FIG. 3 is not executed. In FIG. 5, the solid line LD shows the time-series change of the pressure in the blood pressure measurement cuff 120 when the size of the blood pressure measurement cuff 120 wound around the blood pressure measurement site of the subject is smaller than normal and the blood pressure measurement cuff 120 is more likely to expand than normal. The dotted line LE shows the time-series change of the pressure in the blood pressure measurement cuff 120 when the size of the blood pressure measurement cuff 120 wound around the blood pressure measurement site of the subject is normal and the expandability of the blood pressure measurement cuff 120 is normal. The broken line LF shows the time-series change of the pressure in the blood pressure measurement cuff 120 when the size of the blood pressure measurement cuff 120 wound around the blood pressure measurement site of the subject is larger than normal and the blood pressure measurement cuff 120 is less likely to expand than normal.

[0059] In the example shown in FIG. 5, when the blood pressure measurement process of the subject is performed, the control unit 102 continuously performs feedback control to control the pressurization operation of the pressurization unit 104 according to the deviation between the actual pressurization speed and the target pressurization speed in the blood pressure measurement cuff 120. As a result, when the size of the blood pressure measurement cuff 120 wound around the blood pressure measurement site of the subject is normal and the expandability of the blood pressure measurement cuff 120 is normal, as shown by the dotted line LE in FIG. 5, when the actual pressure in the blood pressure measurement cuff 120 enters the blood pressure measurement range 220, the actual pressurization speed in the blood pressure measurement cuff 120 substantially converges to the target pressurization speed. On the other hand, when the size of the blood pressure measurement cuff 120 wound around the blood pressure measurement site of the subject is smaller than normal and the blood pressure measurement cuff 120 is more likely to expand than normal, as shown by the solid line LD in FIG. 5, when the actual pressure in the blood pressure measurement cuff 120 enters the blood pressure measurement range 220, the actual pressurization speed in the blood pressure measurement cuff 120 does not converge to the target pressurization speed, and when the pressure is P3 or more which is larger than P2, the actual pressurization speed in the blood pressure measurement cuff 120 substantially converges to the target pressurization speed.

[0060] That is, compared with the case where the control operation of the blood pressure measurement device 100 shown in FIG. 3 is executed, the time until the actual pressure increase rate in the blood pressure measurement cuff 120 converges to the target pressure increase rate becomes longer by the amount of change in pressure from P2 to P3, and it is difficult to increase the pressure at the target pressure increase rate in the initial stage after the start of blood pressure measurement of the subject. This is generally because there is a response delay to the control signal in feedback control, and the pressure increase rate in the blood pressure measurement cuff 120 does not immediately change even when a control signal is output, and the control amount is reduced to suppress the occurrence of fluctuations in the pulse wave signal superimposed on the sensor detection signal. In particular, if the actual pressure increase rate in the blood pressure measurement cuff 120 does not converge to the target pressure increase rate at a stage where the actual pressure in the blood pressure measurement cuff 120 is low, a correct pulse wave signal cannot be sufficiently acquired, and the problem arises that the minimum blood pressure of the subject cannot be measured at all or cannot be measured accurately.

[0061] Also, as shown by the broken line LF in FIG. 5, when the size of the blood pressure measurement cuff 120 is larger than normal and the blood pressure measurement cuff 120 is less likely to expand than normal, even when feedback control is performed, the time until the actual pressure in the blood pressure measurement cuff 120 reaches the blood pressure measurement range 220 is much longer compared to the solid line LD and the dotted line LE. In this case, even if the actual pressure increase rate in the blood pressure measurement cuff 120 converges to the target pressure increase rate when the actual pressure in the blood pressure measurement cuff 120 enters the blood pressure measurement range 220, the problem arises that the blood pressure measurement time of the subject becomes very long.

[0062] As described in detail above, the blood pressure measurement device 100 according to the present embodiment includes a pressure increasing unit 104 that performs a pressure increasing operation to increase the pressure in the blood pressure measurement cuff 120 wound around the subject, a calculation unit (control unit 102) that calculates the pressure increase rate (initial pressure increase rate) in the blood pressure measurement cuff 120 before the actual pressure in the blood pressure measurement cuff 120 enters the blood pressure measurement range 220, and a control unit 102 that controls the pressure increasing operation with a predetermined control amount according to the calculated initial pressure increase rate so that the actual pressure increase rate in the blood pressure measurement cuff 120 converges to the target pressure increase rate when the actual pressure in the blood pressure measurement cuff 120 enters the blood pressure measurement range 220.

[0063] According to the present embodiment configured as described above, before the actual pressure in the blood pressure measurement cuff 120 enters the blood pressure measurement range 220, according to the initial pressure increase rate calculated at this stage, when the actual pressure in the blood pressure measurement cuff 120 enters the blood pressure measurement range 220, the pressure increase operation is controlled by a predetermined control amount so that the actual pressure increase rate in the blood pressure measurement cuff 120 converges to the target pressure increase rate. Therefore, compared with the case of performing feedback control to control the pressure increase operation of the pressure increasing unit 104 according to the deviation between the actual pressure increase rate and the target pressure increase rate in the blood pressure measurement cuff 120, the actual pressure increase rate in the blood pressure measurement cuff 120 can be made to approach the target pressure increase rate and converge more quickly. Thus, at the initial stage after the start of blood pressure measurement of the subject, the blood pressure measurement cuff 120 wound around the subject can be pressurized at the target pressure increase rate. As a result, at a stage where the actual pressure in the blood pressure measurement cuff 120 is low, a correct pulse wave signal of the subject can be sufficiently acquired, and the minimum blood pressure of the subject can be accurately measured.

[0064] In addition, in the above embodiment, the blood pressure measurement device 100 may be used for measuring the blood pressure of a subject by using a pressure reduction measurement method in addition to the pressure increase measurement method.

[0065] Further, in the above embodiment, the blood pressure measurement device 100 may be incorporated into a biological information monitor (specifically, a bedside monitor, a telemeter, etc.), a Holter blood pressure monitor, or a blood pressure pulse wave device for measuring biological information and used.

[0066] In addition, each of the above embodiments merely shows an example of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed in a limited manner by these. That is, the present invention can be implemented in various forms without departing from the gist or main features thereof.

Explanation of Reference Numerals

[0067] 100 Blood pressure measurement device 102 Control unit 104 Pressure increasing unit 104A Air supply section 104B Exhaust section 106 Pressure detection section 108 Filter section 110 Memory section 112 Operation section 114 Display section 120 Blood pressure measurement cuff

Claims

1. A blood pressure measurement device that measures the blood pressure of a subject while the pressure inside a cuff wrapped around the subject is increased within a blood pressure measurement range, a pressure increasing unit that performs a pressure increasing operation to increase the pressure inside the cuff, a calculation unit that calculates the pressure increasing speed inside the cuff when the pressure inside the cuff reaches a predetermined pressure smaller than the lower limit value of the blood pressure measurement range before the pressure inside the cuff enters the blood pressure measurement range, a control unit that controls the pressure increasing operation with a predetermined control amount according to the calculated pressure increasing speed so that the pressure increasing speed inside the cuff converges to a target pressure increasing speed when the actual pressure inside the cuff enters the blood pressure measurement range, comprising: the predetermined control amount is a control amount according to a comparison between the calculated pressure increasing speed and a plurality of predetermined pressure increasing speeds, the control unit: compares the calculated pressure increasing speed with a first pressure increasing speed, and when it is determined that the calculated pressure increasing speed is equal to or higher than the first pressure increasing speed, controls the pressure increasing operation with a predetermined first control amount so as to decelerate the pressure increasing speed and converge it to the target pressure increasing speed, when it is determined that the calculated pressure increasing speed is smaller than the first pressure increasing speed, compares the calculated pressure increasing speed with a second pressure increasing speed smaller than the first pressure increasing speed, and when it is determined that the calculated pressure increasing speed is larger than the second pressure increasing speed, controls the pressure increasing operation with a predetermined second control amount so as to decelerate the pressure increasing speed and converge it to the target pressure increasing speed, the first control amount has a larger deceleration amount of the pressure increasing speed inside the cuff than the second control amount, blood pressure measurement device.

2. When it is determined that the calculated pressure increasing speed is smaller than the second pressure increasing speed, the control unit controls the pressure increasing operation with the initial operation amount. The blood pressure measurement device according to claim 1.

3. After controlling the pressure increasing operation with the predetermined control amount, the control unit controls the pressure increasing operation according to the deviation between the actual pressure increasing speed inside the cuff and the target pressure increasing speed. The blood pressure measurement device according to claim 1 or 2.

4. The pressure increasing unit: has an air supply unit that supplies air to the cuff, and an exhaust unit that exhausts air from the cuff, and changes the combination of the control amount of the air supply and the control amount of the exhaust based on the first control amount and the second control amount. The blood pressure measurement device according to any one of claims 1 to 3.

5. A control method for a blood pressure measurement device that measures the blood pressure of a subject while the pressure inside a cuff wrapped around the subject is increased within a blood pressure measurement range, Before the pressure in the cuff enters the blood pressure measurement range, calculate the pressure increase rate in the cuff when a predetermined pressure smaller than the lower limit value of the blood pressure measurement range is reached. A control method for controlling the pressure increase operation of the cuff with a predetermined control amount according to the calculated pressure increase rate so that the pressure increase rate in the cuff converges to the target pressure increase rate when the pressure in the cuff enters the blood pressure measurement range. Including a step of determining according to a comparison between the calculated pressure increase rate for calculating the predetermined control amount and a plurality of predetermined pressure increase rates, and controlling the pressure increase operation. In the step, Compare the calculated pressure increase rate with a first pressure increase rate. When it is determined that the calculated pressure increase rate is equal to or higher than the first pressure increase rate, decelerate the pressure increase rate and control the pressure increase operation with a predetermined first control amount so as to converge to the target pressure increase rate. When it is determined that the calculated pressure increase rate is smaller than the first pressure increase rate, compare the calculated pressure increase rate with a second pressure increase rate smaller than the first pressure increase rate. When it is determined that the calculated pressure increase rate is larger than the second pressure increase rate, decelerate the pressure increase rate and control the pressure increase operation with a predetermined second control amount so as to converge to the target pressure increase rate. The first control amount has a larger pressure increase rate deceleration amount in the cuff than the second control amount. Control method.

6. In the step, when it is determined that the calculated pressure increase rate is smaller than the second pressure increase rate, control the pressure increase operation with the initial operation amount. The control method according to claim 5.

7. After controlling the pressure increase operation with the predetermined control amount, control the pressure increase operation according to the deviation between the actual pressure increase rate in the cuff and the target pressure increase rate. The control method according to claim 5 or 6.

8. Based on the first control amount and the second control amount, change the combination of the control amount of air supply to the cuff and the control amount of exhaust from the cuff. The control method according to any one of claims 5 to 7.

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