Blood pressure measuring device, blood pressure measuring method and blood pressure measuring program

Abstract

A blood pressure measuring device includes: a cuff to be wrapped around a measurement target site; a pressure sensing unit configured to detect cuff pressure; a pressure control unit configured to control the cuff pressure; a blood pressure calculation unit configured to perform blood pressure calculation processing based on the cuff pressure;and a winding strength determination unit configured to perform winding strength determination processing to determine a winding strength of the cuff at the target measurement location, wherein the pressure control unit performs constant pressure control to maintain the cuff pressure at a constant target pressure value from the start of an increase in cuff pressure until the end of the winding strength determination processing, and performs constant rate pressurization control to increase the cuff pressure at a constant rate to calculate the blood pressure after completion of the winding strength determination processing, and wherein the winding strength determination unit determines the winding strength during the constant pressure control.

Description

TECHNICAL AREA

[0001] The present invention relates to a blood pressure measuring device, a blood pressure measuring method and a blood pressure measuring program. STATE OF THE ART

[0002] In recent years, health management has increasingly been carried out by measuring information relating to an individual's body and health, such as blood pressure, using a measuring device and by recording and analyzing the measurement result. An example of the measuring device described above is a sphygmomanometer, which has a function for determining the winding strength of a cuff worn at a target measurement site, such as a patient's upper arm or wrist (see patent document 1).

[0003] In the sphygmomanometer disclosed in patent document 1, after the cuff is applied, a pump is driven by applying a constant voltage to the pump during the initial pressurization, the winding strength of the cuff is determined based on a cuff pressure-pressurization time characteristic (cuff pressure curve) from an initial pressure to a pressure value after the end of the initial pressurization, and subsequently a blood pressure calculation processing takes place.

[0004] However, with such a constant-voltage drive, the initial pressure level must not be set too low in order to ensure sufficient time for the cuff winding to be adjusted. Additionally, since it is necessary to capture a pressure pulse wave for blood pressure calculation immediately after determining the cuff winding strength, noise generated at the time of the control switchover can adversely affect the pressure pulse wave. LITERATURE LIST PATENT LITERATURE

[0005] Patent literature 1: JP 5408142 B BRIEF DESCRIPTION OF THE INVENTIONAL PROBLEM

[0006] In view of the prior art described above, one object of the present invention is to provide a technique that is able to suppress the influence of noise at the time of the control switching from cuff winding strength determination to blood pressure calculation. SOLUTION TO THE PROBLEM

[0007] To solve the aforementioned problems, the present invention provides a blood pressure measuring device which includes: a cuff to be wrapped around a measurement target point; a pressure detection unit configured to detect cuff pressure within the cuff; a pressure control unit configured to control the cuff pressure; a blood pressure calculation unit configured to perform blood pressure calculation processing in order to calculate a patient's blood pressure based on the detected cuff pressure; and a winding strength determination unit configured to perform winding strength determination processing to determine a winding strength of the cuff at the measurement target location, wherein the pressure control unit performs constant pressure control to maintain the cuff pressure at a constant target pressure value from the start of an increase in cuff pressure until the end of the winding strength determination processing, and performs constant rate pressurization control to increase the cuff pressure at a constant rate for calculating the blood pressure after the end of the winding strength determination processing, and where the winding strength determination unit determines the winding strength during constant pressure control.

[0008] According to the configuration above, in constant pressure control for determining cuff winding strength, the control switches from a state in which the cuff pressure is maintained at a constant target pressure value to constant velocity pressure control for blood pressure calculation, making it possible to suppress the influence of noise on blood pressure calculation at the time of switching.

[0009] In the present invention The winding strength determination unit can determine the winding strength based on a change in the sleeve pressure during a target determination period in which the sleeve pressure reaches the target pressure value from an initial pressure and stabilizes thereon.

[0010] According to the configuration above, the winding strength can be determined according to the magnitude of the pressure exerted on the measurement target point by the cuff pressure when the cuff is placed around the measurement target point.

[0011] In the present invention The winding strength determination unit can determine the winding strength by comparing the number of cases in which the cuff pressure falls below the target pressure value during the determination target period with a predetermined threshold and by comparing any difference to the target pressure value with a predetermined threshold.

[0012] According to the above configuration, it is possible to determine, as winding strength, whether the magnitude of a pressure exerted on the measuring point by the cuff pressure when the cuff is wrapped around the measuring point is less than a suitable value.

[0013] In the present invention, the winding strength determination unit can determine the winding strength based on whether the cuff pressure increases or decreases relative to the target pressure value during the determination target period.

[0014] According to the above configuration, it is possible to determine, as winding strength, whether the magnitude of a pressure exerted on the measuring point by the cuff pressure when the cuff is wrapped around the measuring point is greater than a suitable value.

[0015] In the present invention The target pressure value can be less than 30 mmHg.

[0016] According to the configuration above, since the constant pressure control is performed using a cuff pressure of less than 30 mmHg as the target pressure value, the constant velocity pressure control for blood pressure calculation can be started from a state in which the cuff pressure is lower.

[0017] In the present invention The pressure control unit can perform constant speed pressure control depending on a result of the winding strength determination processing.

[0018] According to the configuration above, constant-speed pressure control is performed when the cuff is wound to a suitable tightness, enabling highly accurate blood pressure calculation. Additionally, if the winding tightness is insufficient, the air is released from the cuff without constant-speed pressure control, thus reducing the burden on the patient.

[0019] In the present invention The pressure control unit can perform constant pressure control via a PID controller.

[0020] In the present invention, the pressure control unit can control a pump configured to supply air to the cuff, as well as an outlet valve configured to control the outlet from the cuff.

[0021] The present invention provides a blood pressure measurement method that includes: Detecting cuff pressure in a cuff wrapped around a measurement target point; Performing constant pressure control to maintain the cuff pressure at a constant target pressure value; Performing a winding strength determination process to determine the winding strength of the cuff at the measurement target point during constant pressure control; Performing a constant-speed pressurization control to increase the cuff pressure at a constant rate after the winding strength determination processing has finished; and performing a blood pressure calculation processing to calculate a patient's blood pressure based on the cuff pressure during the constant-speed pressurization control.

[0022] According to the configuration above, in constant pressure control for determining cuff winding strength, the control switches from a state in which the cuff pressure is maintained at a constant target pressure value to constant velocity pressure control for blood pressure calculation, making it possible to suppress the influence of noise on blood pressure calculation at the time of switching.

[0023] The present invention provides a blood pressure measurement program that is configured to cause a computer to execute: Detecting cuff pressure in a cuff wrapped around a measurement target point; Performing constant pressure control to maintain the cuff pressure at a constant target pressure value; Performing a winding strength determination process to determine the winding strength of the cuff at the measurement target point during constant pressure control; Performing a constant-speed pressurization control to increase the cuff pressure at a constant rate after the winding strength determination process has finished; and Performing a blood pressure calculation process to calculate a patient's blood pressure based on the cuff pressure during constant velocity pressure control.

[0024] According to the configuration above, in constant pressure control for determining cuff winding strength, the control switches from a state in which the cuff pressure is maintained at a constant target pressure value to constant velocity pressure control for blood pressure calculation, making it possible to suppress the influence of noise on blood pressure calculation at the time of switching. ADVANTAGEOUS EFFECTS OF THE INVENTION

[0025] According to the present invention, the influence of noise at the time of the control switching from cuff winding strength determination to blood pressure calculation can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a schematic diagram illustrating a hardware configuration of a blood pressure measuring device according to Example 1. Fig. Figure 2 is a functional block diagram of the blood pressure measuring device according to Example 1. Fig. Figure 3 is a flowchart illustrating a complete processing sequence of the blood pressure measuring device according to Example 1. Fig. Figure 4 is a graph illustrating changes over time of a cuff pressure and a pressure pulse wave during the use of the blood pressure measuring device according to Example 1. Fig. Figure 5 is a flowchart showing the process of determining winding strength in the blood pressure measuring device according to Example 1. Fig. Figure 6 is a graph illustrating variation patterns of cuff pressure for each winding strength in the blood pressure measuring device according to Example 1. Fig. Figure 7 is a schematic diagram illustrating a hardware configuration of a blood pressure measuring device according to Example 2. DESCRIPTION OF EXECUTION FORMS

[0026] Embodiments of the present invention are described in detail below with reference to the drawings. Example 1

[0027] An example of the embodiments of the present invention is described below. It should be noted that, unless otherwise specified, the dimensions, material, shape, relative arrangement, and the like of the components described in the present examples are not intended to limit the scope of this invention to them alone. Device configuration

[0028] Fig. Figure 1 is a schematic diagram illustrating a hardware configuration of a blood pressure measuring device 1 according to Example 1.

[0029] The blood pressure measuring device 1 comprises a cuff 11, a pressure sensor 12, a pressure pump 13, an outlet valve 14, an air hose 15, an oscillation circuit 21, a pump drive circuit 22, a valve drive circuit 23, a display unit 25, a memory 24, an operating switch 26, a power source 27, and a CPU 100. The blood pressure measuring device 1 corresponds to a blood pressure measuring device of the present invention. The cuff 11, the pressure pump 13, and the outlet valve 14 each correspond to a cuff, a pump, and an outlet valve of the present invention.

[0030] The cuff 11 includes an air bag 11a containing air. The cuff 11 is equipped with the pressure sensor 12 for detecting pressure in the air bag 11a of the cuff 11 (hereinafter referred to as "cuff pressure"), the pressure pump 13 for supplying air to the air bag 11a, and the outlet valve 14, which is opened and closed to maintain the pressure in the air bag 11a or to release the air from the air bag 11a via the air hose 15.

[0031] The blood pressure measuring device 1 further comprises the central processing unit (CPU) 100 for controlling each unit of the device, the memory 24 for storing a program that is executed for the winding strength determination processing and blood pressure measurement processing described below, and data such as a blood pressure measurement result, the display unit 25 for displaying various types of information such as a winding strength determination result and a blood pressure measurement result, the operating switch 26 for inputting various instructions for measurement, and the power source 27 for powering each unit of the device such as the CPU.

[0032] Additionally, the oscillation circuit 21 outputs a signal to the CPU 100 with an oscillation frequency corresponding to an output value of the pressure sensor 12. The pump drive circuit 22 controls the operation of the pressure pump 13 based on a control signal output by the CPU 100. The valve drive circuit 23 controls the opening and closing of the outlet valve 14 based on a control signal output by the CPU 100.

[0033] Fig. Figure 2 is a functional block diagram of the blood pressure measuring device 1.

[0034] The CPU 100 comprises a pressure detection unit 110, a pressure control unit 120, a blood pressure calculation unit 130, a status determination unit 140, and a winding strength determination unit 150. The pressure detection unit 110, the pressure control unit 120, the blood pressure calculation unit 130, and the winding strength determination unit 150 each correspond to a pressure detection unit, a pressure control unit, a blood pressure calculation unit, and a winding strength determination unit of the present invention.

[0035] An output signal from the oscillator circuit 21 is input into the pressure detection unit 110. The pressure detection unit 110 detects an oscillation frequency of the input signal and converts the detected oscillation frequency into a pressure value signal. The pressure detection unit 110 comprises a high-pass filter (HPF) unit, which extracts and outputs a pressure pulse wave signal by performing HPF processing of the pressure value signal, and a low-pass filter (LPF) unit, which extracts and outputs an absolute pressure value signal by performing LPF processing of the pressure value signal.

[0036] The pressure control unit 120 controls a cuff pressure of the cuff 11 by controlling the operation of the pump drive circuit 22 and the valve drive circuit 23.

[0037] The blood pressure calculation unit 130 receives the pressure pulse wave signal extracted from the HPF unit of the pressure detection unit 110 and processes the received pressure pulse wave signal according to an oscillometric procedure, thereby calculating a diastolic blood pressure (the lowest blood pressure) and a systolic blood pressure (the highest blood pressure).

[0038] A cuff pressure signal, indicating the cuff pressure detected in a time series, is input from the LPF unit of the pressure detection unit 110 to the state determination unit 140. The state determination unit 141 determines whether a condition (determination state) for performing a winding strength determination is met, based on the cuff pressure signal input in a time series.

[0039] The cuff pressure signal, which indicates the cuff pressure detected in a time series, is input from the LPF unit of the pressure detection unit 110 into the winding strength determination unit 150, and the input cuff pressure signal is stored in a predetermined area of ​​the memory 24. The winding strength determination unit 150 waits until the determination condition is met and then performs a winding strength determination, as described below, based on the cuff pressure signal read from the memory 24. Blood pressure measurement methods

[0040] Fig. Figure 3 is a flowchart showing the complete processing sequence of a blood pressure measurement procedure performed by the blood pressure measuring device 1. The entire processing for the blood pressure measurement, which is performed in Fig. As shown in Figure 3, the program is stored in advance in a predetermined area of ​​memory 24 and is implemented when the CPU 100 reads the program from memory 24 and executes it. The program can also be recorded on a computer-readable storage medium and read from the storage medium into the blood pressure measuring device 1. Fig. Figure 4 is a graph illustrating temporal changes of a pressure pulse wave and cuff pressure detected during blood pressure measurement, with both shown on the same time axis.

[0041] During blood pressure measurement, the cuff 11 is first wrapped around a target measurement site, such as a patient's upper arm or wrist. The description assumes that the patient makes a predetermined setting using the operating switch 26, instructing the device to start the blood pressure measurement. It should be noted that the blood pressure measuring device 1, having received the instruction to start the measurement, performs a predetermined initialization, such as opening the outlet valve 14 and adjusting the cuff pressure to atmospheric pressure (initial pressure).

[0042] When blood pressure measurement is started, the pressure control unit 120 initiates constant pressure control (step S1). At this point, the pressure control unit 120 controls the pump drive circuit 22 to maintain the cuff pressure detected by the pressure sensor 12 (referred to as "constant pressure control"), using an initial end-pressure value, which is the cuff pressure at which the initial pressure application ends, as the target pressure value. Constant pressure control can be implemented, for example, by PID control, but the control method is not limited to this.

[0043] The status monitoring unit 140 monitors the cuff pressure detected by the pressure sensor 12 and determines whether the cuff pressure reaches the target pressure value and stabilizes at that value (step S2). Whether the cuff pressure stabilizes can be determined, for example, based on whether a deviation of the cuff pressure from the target pressure value is within a range of ±5%, but this is not the only possible criterion.

[0044] If step S2 determines that the cuff pressure does not reach or stabilize at the target pressure value, step S2 is repeated, and the status unit 140 continues to monitor the cuff pressure. Before proceeding to step S3, the sampled cuff pressure is stored in a predetermined area of ​​memory 24 along with sampling time information.

[0045] If the state determination unit 140 determines in step S2 that the cuff pressure has reached the target pressure value and stabilized at that value, the winding strength determination unit 150 performs a Fig. The winding strength determination process shown in step 5 is based on information about the change in cuff pressure over time stored in memory 24 (step S3). Thus, the winding strength determination process is carried out under constant pressure control.

[0046] During the coil tightness determination process in step S3, the coil tightness determination unit 150 determines the coil tightness based on a variation pattern of the cuff pressure during a period from an initial pressure until the cuff pressure is reached and stabilized under constant pressure control. Here, it is determined into which of three categories—loose coiling, adequate coiling, and tight coiling—the coil tightness of the cuff 11 falls. If the cuff 11 is wrapped around a measurement target site, such as an upper arm, to form a cylindrical shape, and if a circumferential length of the cylinder is substantially equal to a circumference of the measurement target site, the pressure exerted by the cuff 11 on the measurement target site will be at a level suitable for blood pressure measurement; therefore, such a condition is referred to as adequate coiling.If the circumferential length of the cylinder formed by the cuff 11 is shorter than the circumference of the measurement target point, the cuff 11 is tightly wound around the measurement target point, and the pressure exerted by the cuff 11 on the measurement target point is higher than the appropriate level; therefore, such a condition is referred to as a tight winding. If the circumferential length of the cylinder formed by the cuff 11 is longer than the circumference of the measurement target point, the cuff 11 is loosely wound around the measurement target point, and the pressure exerted by the cuff 11 on the measurement target point is lower than the appropriate level; therefore, such a condition is referred to as a loose winding. Here, the time from the initial pressure until the target pressure value is reached and stabilized corresponds to the cuff pressure (in ). Fig. 4. The period P1 to Tc) during constant pressure control is a target determination period of the present invention. Time Tc corresponds to the end of the winding strength determination process.

[0047] Fig. Figure 6 is a graph illustrating an example of variation patterns of cuff pressure when the wrapping strength is determined as loose wrapping, moderate wrapping and tight wrapping. Fig. Figure 6 is an enlarged view showing a section circled by a dashed line, representing the change in cuff pressure in Fig. 4. In the loose winding state, a so-called sub-vibrational state persists, in which the sleeve pressure rises slowly during pressurization and remains significantly below the target pressure value before the target pressure value is reached. In the tight winding state, the sleeve pressure rises sharply immediately after the start of pressurization and exceeds the target pressure value, i.e., it enters a so-called overshoot state. Subsequently, the sleeve pressure rises and falls repeatedly, reaching the target pressure value while fluctuating above and below it. In the appropriate winding state, the sleeve pressure rises with pressurization but does not exceed the target pressure value and reaches it after a rapid approach.

[0048] The winding strength determination unit 150 determines whether the number of instances and the amount by which the sleeve pressure falls below the target pressure value, from the initial pressure until the target value is reached by the sleeve pressure, exceed predetermined threshold values ​​(step S31). Here, the amount below the target pressure value refers to the magnitude of the difference between the target pressure value and the sleeve pressure.

[0049] If in step S31 it is determined that the number of cases and the amount by which the cuff pressure is below the target pressure value until the cuff pressure reaches the target pressure value are greater than the predetermined thresholds, it is determined that the winding strength is a loose winding (step S32).

[0050] If in step S31 it is determined that the number of cases and the amount by which the sleeve pressure is below the target pressure value until the sleeve pressure reaches the target pressure value are equal to or less than the predetermined thresholds, the winding strength determination unit 150 determines whether the pressure value increases or decreases with respect to the target pressure value (step S33).

[0051] If in step S33 it is determined that the pressure value increases or decreases relative to the target pressure value until the cuff pressure reaches the target pressure value, it is determined that the winding strength is a fixed winding (step S34).

[0052] If in step S33 it is determined that the cuff pressure value neither increases nor decreases relative to the target pressure value until the cuff pressure reaches the target pressure value, it is determined that the winding strength is an appropriate winding (step S35).

[0053] If the winding strength determination in step S3 determines that the winding is suitable, the initial pressurization by the constant pressure control is terminated, and the pressure control unit 120 begins to control the pump drive circuit 22 so that the sleeve pressure increases at a constant rate (referred to as "constant rate pressurization control") (step S5). The constant rate pressurization control is active for a period P2 after Tc in Fig. 4 executed.

[0054] The final pressure value (target pressure value) after initial pressurization is set to a pressure of less than 30 mmHg, which is a typical pressure during a state-of-the-art constant voltage drive, for example, around 10 mmHg. By setting the final pressure value to a low level after initial pressurization in this way, pressure pulse waves for blood pressure measurement can be detected even at lower pressures after the winding strength determination process has ended.

[0055] Additionally, after completion of the winding strength determination processing in step S3, a pump voltage (a drive voltage of the pump drive circuit 22) is maintained in a state of equilibrium during constant pressure control, and the control is switched from this state to constant-speed pressurization control to begin acquiring pressure pulse waves for blood pressure measurement. This prevents a sudden change in the pressurization rate, thereby suppressing the influence of noise at the time of the control switchover and enabling the detection of clear changes in the pressure pulse wave.

[0056] The blood pressure calculation unit 130 performs a blood pressure calculation processing in which, under constant velocity pressure control, a pressure pulse wave for blood pressure measurement is detected by the HPF unit of the pressure detection unit 110 and a blood pressure value such as a systolic blood pressure and a diastolic blood pressure is calculated by an oscillometric method (step S6).

[0057] The CPU 100 displays the measurement result, such as the blood pressure value calculated in step S6, on the display unit 25 of the blood pressure measuring device 1 (step S7). Then, the CPU 100 records the measurement result, such as the blood pressure value calculated in step S6, in a predetermined area of ​​the memory 24 of the blood pressure measuring device 1 (step S8) and terminates the blood pressure measurement processing.

[0058] If, during the coil strength determination processing in step S3, it is determined that the coil strength is inadequate, i.e., if it is determined that the coil is loose or tight, the pressure control unit 120 controls the valve actuator circuit 23 to open the outlet valve 14, thereby releasing air from the air bag 11a of the cuff 11 (step S9). Then, the CPU 100 causes the display unit 25 to indicate an error (step S10) and terminates the blood pressure measurement processing. Example 2

[0059] Fig. Figure 7 is a block diagram illustrating a hardware configuration of a blood pressure measuring device 2 according to Example 2. Configurations corresponding to those of the blood pressure measuring device 1 according to Example 1 are indicated by the same reference symbols, and a detailed description is omitted here.

[0060] The blood pressure measuring device 2 includes a control valve 16 and a control valve actuator circuit 28 in place of the outlet valve 14 and the valve actuator circuit 23, and further includes a rapid outlet valve 17 and a rapid outlet valve actuator circuit 30. The blood pressure measuring device 2 corresponds to a blood pressure measuring device of the present invention. Additionally, the control valve 16 corresponds to an outlet valve of the present invention.

[0061] The control valve 16 is a valve whose opening degree can be continuously controlled, and the control valve actuator circuit 28 controls the opening degree of the control valve 16 by means of a control signal output by the CPU 100. The quick-release valve 17 is a valve that can rapidly release air and immediately reduce the cuff pressure by opening the valve. The quick-release valve actuator circuit 30 controls the opening and closing of the quick-release valve 17 by means of a control signal output by the CPU 100. In the blood pressure measuring device 2, the pressure control unit 120 controls the operation of the pump actuator circuit 22, the control valve actuator circuit 28, and the quick-release valve actuator circuit 29.

[0062] Since it is difficult to precisely control the cuff pressure with the pressurizing pump 13, constant pressure control at low pressure can be achieved more quickly by combining it with the control valve 16, which allows for slow deflation. The control valve 16 is controlled to open and close during constant pressure control, but it is closed during constant-speed pressurization control.

[0063] The entire processing sequence for blood pressure measurement, including the winding strength determination processing, corresponds to that of the blood pressure measuring device 1 according to Example 1, so that the description is omitted here.

[0064] Additionally, the blood pressure measuring device 2 includes the quick-release valve 17, which allows the cuff pressure to be reduced quickly during deflation, thus reducing the strain on the patient. List of reference symbols 1, 2 Blood pressure measuring device 11 cuff 110 Pressure detection unit 120 Pressure control unit 130 blood pressure calculation units 150 winding strength determination unit QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 5408142 B

[0005]

Claims

[1] Blood pressure measuring device, comprising: a cuff to be wrapped around a measurement target point; a pressure detection unit configured to detect cuff pressure within the cuff; a pressure control unit configured to control the cuff pressure; a blood pressure calculation unit configured to perform blood pressure calculation processing in order to calculate a patient's blood pressure based on the detected cuff pressure; and a winding strength determination unit configured to perform winding strength determination processing to determine a winding strength of the cuff at the measurement target location, wherein the pressure control unit performs constant pressure control to maintain the cuff pressure at a constant target pressure value from the start of an increase in cuff pressure until the end of the winding strength determination processing, and performs constant rate pressure application control to increase the cuff pressure at a constant rate for calculating the blood pressure after the end of the winding strength determination processing, and where the winding strength determination unit determines the winding strength during constant pressure control. [2] Blood pressure measuring device according to claim 1, wherein the winding strength determination unit determines the winding strength based on a change in the cuff pressure during a target determination period in which the cuff pressure reaches the target pressure value from an initial pressure and stabilizes thereon. [3] Blood pressure measuring device according to claim 2, wherein the winding strength determination unit determines the winding strength by comparing the number of cases in which the cuff pressure falls below the target pressure value during the determination target period with a predetermined threshold and by comparing a difference from the target pressure value with a predetermined threshold. [4] Blood pressure measuring device according to claim 2 or 3, wherein the winding strength determination unit determines the winding strength on the basis of whether the cuff pressure increases or decreases relative to the target pressure value during the determination target period. [5] Blood pressure measuring device according to claim 1 or 2, wherein the target pressure value is less than 30 mmHg. [6] Blood pressure measuring device according to claim 1 or 2, wherein the pressure control unit performs the constant speed pressure control depending on a result of the winding strength determination processing. [7] Blood pressure measuring device according to claim 1 or 2, wherein the pressure control unit performs the constant pressure control by means of a PID controller. [8] Blood pressure measuring device according to claim 1 or 2, wherein the pressure control unit controls a pump configured to supply air to the cuff and an outlet valve configured to control the outlet from the cuff. [9] Blood pressure measurement methods, comprehensive: Detecting cuff pressure in a cuff wrapped around a measurement target point; Performing constant pressure control to maintain the cuff pressure at a constant target pressure value; Performing a winding strength determination process to determine the winding strength of the cuff at the measurement target point during constant pressure control; Performing a constant-speed pressurization control to increase the cuff pressure at a constant rate after the winding strength determination process has finished; and Performing a blood pressure calculation process to calculate a patient's blood pressure based on the cuff pressure during constant velocity pressure control. [10] Blood pressure measurement program configured to cause a computer to execute: Detecting cuff pressure in a cuff wrapped around a measurement target point; Performing constant pressure control to maintain the cuff pressure at a constant target pressure value; Performing a winding strength determination process to determine the winding strength of the cuff at the measurement target point during constant pressure control; Performing a constant-speed pressurization control to increase the cuff pressure at a constant rate after the winding strength determination processing has finished; and performing a blood pressure calculation processing to calculate a patient's blood pressure based on the cuff pressure during the constant-speed pressurization control.

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