JP3728486B2 - Sphygmomanometer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sphygmomanometer that measures blood pressure by changing and extinguishing the magnitude of a pulse wave generated in synchronization with pulsation while compressing an artery with a pressurized air bag and reducing the pressure stepwise.
[0002]
[Prior art]
In the conventional blood pressure measurement, a pressurized air bag (pressurized bag) is pressurized to the maximum blood pressure value or higher, and the air in the pressurized bag is exhausted at a speed of 2 to 3 mmHg / sec. The magnitude of the pulse wave superimposed on the pressure in a certain pressure bag is detected and stored in pairs with the pressure of the pressure bag in time series. The pressure value of the pressurization bag at the time of the beat when the pulse wave magnitude is the maximum from the stored time series data is the average blood pressure value, the pressure higher than the average blood pressure value of the pressurization bag, and the magnitude of the pulse wave Let the pressure value of the pressure bag at the timing of the pulse wave pulse closest to about 50% of the maximum value of the pulse wave be the maximum blood pressure value. Further, the pressure value of the pressure bag at the timing of the pulse whose magnitude of the pulse wave is closest to about 60% of the maximum value of the pulse wave at the pressure value lower than the average blood pressure value is set as the minimum blood pressure value. There is an oscillometric method based on the oscillometric method.
[0003]
In the Korotkoff sound method based on the Korotkoff method, the Korotkoff sound sensor (K sound) generated in synchronization with the pulse is detected by the Korotkoff sound sensor installed on the distal side when the pressure bag is attached, and the beat generated by the Korotkoff sound is detected. The pressure value of the pressurized bag at the point of time is monitored for the maximum blood pressure value, and the subsequent Korotkoff sound is monitored continuously, and the pressure of the pressurized bag at the time of the last beat when the Korotkoff sound disappears is set as the minimum blood pressure value. The method is used.
[0004]
In both of these types, the pressure value of the pressure bag obtained as the blood pressure value is the pressure of the pressure bag at the timing synchronized with the beat. The pressure value of the pressure bag between the beats cannot be a measured value, and the amount of decompression per beat becomes the minimum resolution of the measurement, resulting in an error. That is, the measurement accuracy depends on the pulse wave rate. If the slow exhaust speed is 2 to 3 mmHg / second, for example, if the pulse rate is 60 beats / minute, it is 2 to 3 mmHg. In the case of / min, the accuracy deteriorates to 3 to 4.5 mmHg. On the other hand, if the pulse rate is large, it becomes more than necessary for measurement, and there is a limit to the blood pooling volume at the peripheral part than the part where the pressure bag is attached, so it is easy to cause congestion, Pulse waves and Korotkoff sounds are attenuated, which hinders measurement. In addition, when the pulse is fast, it takes more measurement time than necessary, resulting in extra pain for the patient. Therefore, it is desirable to control the decompression speed so as to become a constant speed according to the pulse rate.
[0005]
There are two methods to make the pressure reduction per beat constant: linear pressure reduction method and stepped pressure reduction (step pressure reduction) method. Linear pressure reduction method controls the pressure reduction speed to a constant slope of 2 to 3 mmHg / sec during measurement. Therefore, it is necessary to measure the pressure reduction speed and adjust the orifice diameter of the exhaust port, and in particular, when the pressure is high, it is necessary to perform in a delicate manner.
[0006]
This control results in a decrease in the pressure change of the pressure bag due to a change in the blood vessel volume under the pressure bag, which contradicts the purpose of detecting the magnitude of the pulse wave, and the pulse wave valve mechanism and control mechanism. However, it requires a precise and expensive one, and has the disadvantage that it becomes an obstacle to supplying the sphygmomanometer to the user at a low cost.
[0007]
On the other hand, in the case of the stepped pressure reduction method, the pulse wave is first detected by stopping the pressure reduction, and the pulse wave is detected by instantaneously reducing the pressure by 2 to 3 mmHg when the detection is completed. In addition, the pressure is reduced in a stepped manner so as to reduce the pressure to 2 to 3 mmHg, the pressure reduction is stopped, and the measurement is repeated. With this method, when the pressure is high, the valve opening time is shortened, and when the pressure is low, the valve opening time is long.In addition, the pulse wave is not detected during decompression speed control. Unlike the linear decompression method, it does not affect the detection of the pulse wave, and does not contradict the purpose of detecting the pulse wave. In addition, a mechanism widely used in general blood pressure monitors can be realized with a simple electromagnetic valve for an exhaust valve, and can be supplied at low cost by a user.
[0008]
[Problems to be solved by the invention]
In the case of the stepped pressure reduction method, the pulse wave must be detected in a state in which the pressure reduction is stopped after the pressure reduction of 2 to 3 mmHg for each step. Due to the compliance of the entire cuff including the amount of air, the viscoelasticity of the living body, and the response of the pressure sensor, a phenomenon (rebound phenomenon) in which the pressure rises excessively from the state where the decompression is stopped is observed. When the bag pressure is lowered, it tends to increase. Therefore, since the rebound phenomenon and the pressure change due to the pulse wave overlap, it becomes an obstacle to the accurate detection of the pulse wave size, resulting in a large error factor in the calculation of the blood pressure value by the oscillometric method.
[0009]
FIG. 9 shows a change in the magnitude of the pulse wave overlapping with the rebound phenomenon by a broken line, and a change in the true pulse wave by a solid line. Therefore, at each pressure bag pressure, the difference in the magnitude of the pulse wave indicated by the solid line and the broken line is the influence of the magnitude of the pulse wave due to the rebound phenomenon. The systolic blood pressure value calculated with the true pulse wave indicated by the solid line is a pulse wave at a point of 50% of the pulse wave of P8 which is the maximum value of the pulse wave. This is a pulse wave of P4, and the maximum blood pressure value is 111 mHg. On the other hand, the systolic blood pressure value calculated by the magnitude of the pulse wave affected by rebound is the pulse wave at the point of 50% of the pulse wave indicated by the broken line of P8, which is the maximum value of the pulse wave, This is a pulse wave of P6, and the maximum blood pressure is 105 mHg. Thus, the true systolic blood pressure value includes an error due to the influence of the rebound phenomenon. The minimum blood pressure value is 60% of the maximum pulse wave (P8), so if the true pulse wave value is used, it is 93mHg at the P10 point and is affected by the rebound phenomenon. When the pulse wave value is used, it becomes 90 mHg at the point of P11, which also includes an error.
[0010]
In order to cope with this, a system is used in which the pulse wave and the rebound phenomenon are separated in frequency by a high-pass filter. The cut-off frequency of this high-pass filter must be lower than about 0.5 Hz because the pulse wave frequency is low. Therefore, when an excessive input enters the high-pass filter, it takes 2 seconds or more for the system to stabilize. The pressure fluctuation due to the decompression stop becomes an excessive input, and there is a disadvantage that the detection of the pulse wave is interrupted for 2 seconds or more. In addition, the high-pass filter requires expensive electrical components such as an amplifier and a capacitor, which has been an obstacle to supply to the user at a low cost.
[0011]
[Means for Solving the Problems]
The present invention solves the above-mentioned problems by reducing pressure stepwise in a sphygmomanometer that measures the blood pressure by generating and extinguishing Korotkoff sound while pressing the target artery with a pressure bag and reducing the pressure body in a stepwise manner. A first measuring means for measuring an increase in the time length T immediately before the time point when the pressure in the pressurizing bag is detected as the start of riding of the pulse wave component when the decompression is stopped at the stage, and a rebound component A second measuring means for measuring the magnitude of the provisional pulse wave to ride; a correcting means for correcting the magnitude of the provisional pulse wave measured by the second measuring means based on the increase; and the correction. This is achieved by a sphygmomanometer having output means for outputting the blood pressure value with the value corrected by the means.
[0012]
Another object of the present invention is to detect a pulse wave caused by pulsation while compressing the target artery with a pressure bag and depressurizing the pressure body in a step-like manner, and by changing the magnitude of the pulse wave. In a sphygmomanometer that measures blood pressure, when the decompression is stopped at each step where the pressure is reduced stepwise, the pressure in the pressure bag is a time length T immediately before the time point at which the pulse wave component is detected as being started . a first measuring means for measuring the rise, and a second measuring means for measuring the magnitude of the pulse wave of temporary ride rebound component, based on the rise, the second measuring means to measure provisionally Correction means for correcting the magnitude of the pulse wave , and output means for outputting the magnitude of the pulse wave component corrected by the correction means to a blood pressure determination means for calculating a blood pressure value based on a change in the magnitude of the pulse wave Achieved by a sphygmomanometer with.
[0013]
The horizontal axis of FIG. 1 is time (seconds), and the vertical axis is the pressure (mmHg) of the pressure bag, which is extracted from a certain period of measurement. W1 indicates the pressure change of the pressure bag and connects the pressure sampling points. W2 is a pressure reduction end point, W3 is a point t seconds before the pulse wave bottom point, W4 is a pulse wave bottom point, W5 is a pulse wave peak point, and W6 is a pressure reduction start point.
[0014]
FIG. 2 is a block diagram illustrating a configuration of the measurement apparatus according to the first embodiment. In FIG. 2, 1 is a cuff containing a pressurized air bag, 2 is a Korotkoff sound detection microphone, 3 is a connector for connecting the cuff and the sphygmomanometer body, 4 is a constant current source, and 5 is a pressure of the pressurized bag. 6 is a DC amplifier that amplifies the pressure signal, 7 is an A / D converter that digitizes the pressure signal, 8 is a filter amplifier that discriminates and amplifies the Korotkoff sound, and 9 is an A / D that digitizes the Korotkoff sound. D converter 10 is a central control CPU (microcomputer), 11 is a display unit for displaying the measured blood pressure value, 12 is an exhaust valve control unit, 13 is an electromagnetic exhaust valve, and 14 is a pressurizing pump. , 15 is the stabilization and ON / OFF of the power source, a power control unit for monitoring the battery voltage, 16 is the battery, 17 is the air tube, and 18 is the start / stop SW.
[0015]
In FIG. 1, the detection of the pulse wave bottom point is started from the decompression end point (W2), and when a change of a certain threshold value a or more is detected, the point detected immediately before is detected as the pulse wave bottom point (W4). Further, the pressure is detected for a certain time b, and the peak point of the pulse wave of the maximum pressure value during the period b is set to (W5). The magnitude of the provisional pulse wave is defined as a differential pressure value between the pressure value at the peak point (W5) of the pulse wave and the pressure value at the bottom point (W4) of the pulse wave.
[0016]
The pressure difference between the point (W3) t seconds before the pulse wave bottom point (W4) and the pulse wave bottom point (W4) is calculated, and this pressure difference is defined as an excessive change in the pressure of the pressure bag. The constant σ in the pressure difference (the true pulse wave size that discriminates the rebound phenomenon and pulse wave by the frequency discrimination method described above and the temporary pulse wave size detected by the method of the present application are measured simultaneously. The value obtained by multiplying the magnitude of the provisional pulse wave by a value obtained by statistically analyzing the correlation using clinical data is subtracted from the magnitude of the provisional pulse wave to obtain the true pulse wave magnitude.
[0017]
Although the constant σ is about 0.8, it slightly differs depending on the size of the cuff (1) and the type of the pressure sensor (5).
[0018]
Temporary pulse wave size = A
Pressure value of the pressure bag at the bottom point of the pulse wave = Pb
Pressure value of the pressure bag t time before the bottom point of the pulse wave = Pt
True pulse wave magnitude Ar = A × (1−σ × (Pb−Pt)) (1)
Therefore, if the pressure value at the peak point of the pulse wave is Bp, the true blood pressure value BP is expressed by the following equation (2):
BP = Bp−Ar (2)
It is obtained by
[0019]
The above description will be described with reference to FIGS. 3 and 4 so as to make it easier to understand. 3 and 4 are enlarged views of a part of the pressure measurement waveform shown in FIG. As shown in FIG. 3, when a pulse wave whose actual magnitude is a is superimposed on the rebound component, the pulse wave A having an apparent magnitude Bp-Pb is obtained. Therefore, as shown in FIG. 4, the amount of change (Pb-Pt) of the rebound component over the length of the time length t before the pulse wave starts is obtained as the rebound component from the pulse wave of the apparent magnitude A. The magnitude of the pulse wave Ar is obtained. Next, a series of blood pressure measurement operations of the sphygmomanometer according to the present embodiment in which the Korotkoff sound method and the oscillometric method are provided will be described with reference to the flowcharts of FIGS.
[0020]
First, a cuff (1) containing a pressure bag is wound around the arm. Next, when the start / stop SW (18) is turned on, the CPU (10) detects this, and performs blood pressure measurement after performing a necessary reset operation. First, in response to a command from the CPU (10), the electromagnetic exhaust valve (13) is opened to the atmosphere in the OFF state, and the pressure sensor (5) is reset to zero (step S1). Subsequently, the electromagnetic exhaust valve (13) is closed (step S2), and the pump (14) is driven to pressurize the cuff (1) to a pressure (pressure target value) higher than the expected maximum blood pressure. (Step S3).
[0021]
Next, when the target pressurization value is reached, it is determined whether or not the cuff pressurization is sufficient. If it is determined that the cuff pressurization is insufficient, the pressurization target value is increased by about 30 mmHg and re-applied. Pressure is applied (steps S4 and S5). Here, the determination of whether or not the cuff pressurization is sufficient is performed, for example, by detecting Korotkoff sound by the microphone (2). If the Korotkoff sound is detected, it is determined that the cuff is not pressurized to a pressure higher than the maximum blood pressure, that is, the cuff is not sufficiently pressurized.
[0022]
When the target pressure is higher than the maximum blood pressure, first, the pulse wave bottom point and pulse wave peak point are detected without reducing pressure (step S6). If a pulse wave is detected, the magnitude of the pulse wave is detected from the measured value, the true pulse wave magnitude Ar is obtained using equation (1), and stored in pairs with the measured pressure value Bp. (Step S7).
[0023]
In step S7, first, a pulse wave bottom A and a peak point are detected to detect a provisional pulse wave magnitude A. Then, the degree of the rebound phenomenon is detected from the cuff pressure value t time before the bottom point of the pulse wave and the pressure value at the bottom point of the pulse wave, and the equation (1) is used from the magnitude A of the temporary pulse wave. Then, the true pulse wave magnitude Ar is calculated. Then, the calculated magnitude of the true pulse wave is stored in the internal memory of the CPU (10) as a pair with the pressure value Bp.
[0024]
Further, the Korotkoff sound signal is detected by the microphone 2 (step S8). If a Korotkoff sound is detected, the magnitude of the Korotkoff sound is detected (step S9), and the magnitude of the Korotkoff sound is stored in correspondence with the pressure value (step S10).
[0025]
Next, in step S11, it is determined whether or not the maximum value of the detected pulse wave magnitude has been obtained. If the maximum value of the pulse wave is not yet obtained, the process proceeds to step S12, and step pressure reduction of about 2 to 3 mHg is performed.
[0026]
In step S12, in order to reduce the cuff pressure by 2 to 3 mmHg, the exhaust control unit (12) performs electromagnetic exhaust by the electromagnetic exhaust valve opening time corresponding to the cuff pressure stored in advance in the memory of the CPU (10). The valve (13) is opened, the pressure is released to the atmosphere, and the pressure is reduced instantaneously by 2-3 mmHg. When the step pressure reduction is finished, the electromagnetic exhaust valve (13) is closed to stop the pressure reduction, and the detection and storage of the true pulse wave magnitude and the detection and storage of the Korotkoff sound are executed (step). S6-S10). The true pulse wave magnitude and the Korotkoff sound magnitude are stored in association with the measured pressure value Bp.
[0027]
When the processes in steps S6 to S12 are repeated and the maximum value of the pulse wave size is detected, the process proceeds from step S11 to step S13. In step S13, it is determined whether or not the current pulse wave magnitude is greater than 25% of the maximum value. If greater than 25%, the process proceeds to step S12, and if not, the process proceeds to step S14. That is, even after the maximum pulse wave is detected, step pressure reduction and pulse wave and Korotkoff sound detection (S6 to S10) are repeated until the magnitude of the pulse wave becomes 25% or less of the maximum value.
[0028]
As described above, when the maximum value is detected for the pulse wave, and the subsequent pulse wave value is 25% or less of the maximum value, the process proceeds to step S14, and the electromagnetic exhaust valve (13) is turned on. Open and reduce cuff pressure to atmospheric pressure.
[0029]
Next, it is determined whether or not Korotkoff sound has been detected, that is, whether or not blood pressure measurement has been performed by the Korotkoff sound method (step S15). If detected, the maximum blood pressure value and minimum blood pressure value by the Korotkoff sound method are determined. The measured blood pressure value is displayed (steps S16 and S17). If the Kortkoff sound is not detected, the maximum blood pressure value and the minimum blood pressure value of the oscillometric method are displayed as blood pressure values (steps S18 and S19).
[0030]
Since the pulse wave component is on the blood pressure value measured by the sphygmomanometer, the pulse wave component included in the measured blood pressure value is excluded using the formula (2), and the true pressure value BP is obtained. Swap to find the true maximum and minimum blood pressure without error. The processing according to the equation (2) is performed in steps S16 and S18 based on the data stored in steps S6 to S10.
[0031]
As described above, pressure reduction of 2 to 3 mmHg / beat is performed by opening / closing control of the electromagnetic exhaust valve (13), the magnitude of the pulse wave and the presence or absence of Korotkoff sound are detected, the magnitude of the pulse wave (Ar), cuff The pressure value (Bp) and the magnitude of the Korotkoff sound are stored together in a memory. Such a process is repeated for each beat.
[0032]
Here, the systolic blood pressure value of the Korotkoff sound method is the cuff pressure value at which Korotkoff sound was first detected as the Korotkoff sound systolic blood pressure value. The cuff pressure value at which the pulse wave is detected is set as the minimum blood pressure of the Korotkoff sound method.
[0033]
As described above, when the blood pressure can be measured by the Korotkoff sound method, the blood pressure value of the Korotkoff method is displayed on the display unit (11) as the blood pressure value (step S17). However, if the Korotkoff sound cannot be detected, the blood pressure value of the oscillometric method having the best correlation with the auscultation method widely used in medical institutions is calculated (step S18) and displayed on the display unit (11). (Step S19).
[0034]
In this case, the maximum blood pressure value and the minimum blood pressure value of the oscillometric method are calculated from the pressure value paired with the magnitude of the pulse wave stored in the internal memory of the CPU (10) by the above oscillometric formula (step S18).
[0035]
All operations are stopped by turning off the start / stop switch.
[0036]
(Embodiment 2)
A second embodiment of the present invention will be described with reference to FIGS.
[0037]
The horizontal axis of FIG. 1 is time (seconds), and the vertical axis is the pressure (mmHg) of the pressure bag, which is extracted from a certain period of measurement. (W1) indicates the pressure change of the pressure bag and connects the pressure sampling points. (W2) is the decompression end point, (W3) is the point t seconds before the pulse wave bottom point, (W4) is the pulse wave bottom point, (W5) is the pulse wave peak point, and (W6) is the decompression start It is a point.
[0038]
7 in FIG. 7 is a cuff containing a pressurized air bag, 3 is a connector for connecting the cuff and the sphygmomanometer body, 4 is a constant current source, 5 is a pressure sensor for detecting the pressure of the pressurized bag, and 6 is a pressure signal. Amplifying DC amplifier, 7 is an A / D converter that digitizes a pressure signal, 10 is a CPU (microcomputer) that is a control center, 11 is a display unit that displays a measured blood pressure value, and 12 is an exhaust valve control unit , 13 is an electromagnetic exhaust valve, 14 is a pressurizing pump, 15 is power supply stability and ON / OFF, a power control unit for monitoring battery voltage, 16 is a battery, 17 is an air pipe, and 18 is a start / stop switch. is there.
[0039]
In FIG. 1, the detection of the pulse wave bottom point is started from the decompression end point (W2), and when a change of a certain threshold value a or more is detected, the point detected immediately before is detected as the pulse wave bottom point (W4). Further, the pressure during a certain time b is detected, and the maximum pressure value during this period b is set as the peak point (W5) of the pulse wave. The magnitude of the provisional pulse wave is defined as a differential pressure value between the pressure value at the peak point (W5) of the pulse wave and the pressure value at the bottom point (W4) of the pulse wave.
[0040]
The pressure difference between the point (W3) t seconds before the pulse wave bottom point (W4) and the pulse wave bottom point (W4) is calculated, and this pressure difference is defined as an excessive change in the pressure of the pressure bag. Constant σ in the pressure difference (the true pulse wave that discriminates the rebound phenomenon and pulse wave by the frequency discrimination method described above, and the temporary pulse wave detected by the method of the present application are simultaneously measured. A value obtained by multiplying the magnitude of the provisional pulse wave by a value obtained by statistically analyzing the correlation with the data is subtracted from the magnitude of the provisional pulse wave to obtain the true pulse wave magnitude.
[0041]
The constant σ is 0.8, but this value varies slightly depending on the size of the cuff and the type of pressure sensor.
[0042]
Temporary pulse wave size = A
Pressure value of the pressure bag at the bottom point of the pulse wave = Pb
Pressure value of the pressure bag t time before the bottom point of the pulse wave = Pt
True pulse wave magnitude Ar = A (1−σ × (Pb−Pt)) (1)
Similarly, the true blood pressure value BP is obtained by the above-described second equation.
[0043]
BP = Bp− Ar (2)
Hereinafter, a series of blood pressure measurement operations will be described according to the flowchart of FIG. When the cuff (1) containing the pressurized air bag is wound and the start / stop SW (18) is turned on, the CPU (10) detects this, initializes (resets) the device, and starts blood pressure measurement. .
[0044]
The electromagnetic exhaust valve (13) is opened by the designation of the CPU (10), the pressure is released to the atmosphere, and the pressure sensor (5) is zero-set (step S101). Next, the electromagnetic exhaust valve (13) is closed, and the pump (14) is driven to pressurize the cuff (1) to a pressure higher than the expected maximum blood pressure (step S102). Here, it is determined whether or not pressurization is insufficient, and when it is determined that pressurization is insufficient, repressurization is further performed by about 30 mmHg.
[0045]
The electromagnetic exhaust valve (13) is turned off and released to the atmosphere by the exhaust valve control section (12) for the electromagnetic exhaust valve opening time corresponding to the cuff pressure stored in advance in the memory of the CPU (10), and the air is released to 2 to 3 mmHg. The pressure is reduced instantaneously (step S105). Next, the electromagnetic exhaust valve (13) is closed and decompression is interrupted, and the bottom point and peak point of the pulse wave are detected as described above to calculate the magnitude of the temporary pulse wave (step S104). Further, the degree of the rebound phenomenon is detected from the cuff pressure value t time before the bottom point of the pulse wave and the pressure value at the bottom point of the pulse wave, and from the actually measured magnitude of the temporary pulse wave A, the equation (1) The true pulse wave magnitude Ar is calculated, and the true pulse wave magnitude is paired with the true pressure value (BP: calculated based on equation (2)) in the internal memory of the CPU (10). (Step S104a). Of course, as shown in the first embodiment, the measured value Bp may be stored at this time, and the true pressure value may be obtained when the blood pressure value is calculated by the oscillometric method later.
[0046]
When the processes of S104, S104a, and S105 are repeated to complete the pressure reduction to a predetermined pressure, the blood pressure value is calculated by the oscillometric method from the pulse wave and pressure value data stored in the memory (S106), and the obtained blood pressure value is obtained. Is stored (S107). Then, it is displayed on the display unit (step S108).
[0047]
【The invention's effect】
As described above, according to the present invention, the magnitude of the pulse wave or the blood pressure value can be measured in any of the Korotkoff sound method, the oscillometric method, or the combination of the Korotkoff sound method and the oscillometric method. Measurement without the influence of the rebound phenomenon appearing in
[0048]
Further, expensive electronic components such as an amplifier and a capacitor for discriminating the rebound phenomenon and the pulse wave in terms of frequency become unnecessary, and an inexpensive sphygmomanometer can be supplied to the user.
[0049]
[Brief description of the drawings]
FIG. 1 is a view showing a pressure change with respect to time of a pressure bag.
FIG. 2 is a block diagram showing a configuration of a measurement apparatus according to Embodiment 1 of the present invention.
FIG. 3 is an explanatory diagram showing a relationship between a pulse wave and a rebound component on which the pulse wave rides.
4 is a detailed view of FIG. 3;
FIG. 5 is a flowchart of a control procedure executed by the apparatus according to the first embodiment.
FIG. 6 is a flowchart of a control procedure executed by the apparatus according to the first embodiment.
7 is a block diagram of a measuring apparatus according to Embodiment 2. FIG.
FIG. 8 is a flowchart of a control procedure executed by the apparatus according to the second embodiment.
FIG. 9 is a diagram showing a change in the magnitude of a pulse wave that overlaps with the rebound phenomenon and a change in a true pulse wave.
[Explanation of symbols]
1 Cuff 5 Pressure sensor 6 Amplifier 7, 9 A / D converter 12 Exhaust controller 13 Exhaust valve

Claims (6)

In a sphygmomanometer that measures the blood pressure by generating and extinguishing the Korotkoff sound while pressing the target artery with a pressure bag and reducing the pressure body in a staircase shape,
A first measurement is made to measure an increase in time length T immediately before a point in time when the pressure in the pressure bag is detected as the start of the pulse wave component when the decompression is stopped at each stage where the pressure is reduced stepwise. Measuring means;
A second measuring means for measuring the magnitude of the provisional pulse wave riding on the rebound component;
Correction means for correcting the magnitude of the provisional pulse wave measured by the second measurement means based on the increase;
A sphygmomanometer comprising output means for outputting a blood pressure value with the value corrected by the correction means. The first measuring means uses the difference in pressure in the pressure bag at the start and end of the time length T as the increase, and the increase is D, and the pulse measured by the second measurement means. When the magnitude of the wave component is A and σ is a predetermined constant, the correction means
Ar = A × (1−σ × D)
The sphygmomanometer according to claim 1, wherein the magnitude Ar of the pulse wave component after correction is calculated by the calculation.   The sphygmomanometer according to claim 1, wherein the first measuring means is a pressure sensor that detects a pressure in the pressurizing air bag and outputs a pressure signal representing the pressure. In a sphygmomanometer that presses a target artery with a pressure bag, detects a pulse wave generated by pulsation while reducing the pressure body in a stepped manner, and measures blood pressure by a change in the magnitude of the pulse wave,
A first measurement is made to measure an increase in time length T immediately before a point in time when the pressure in the pressure bag is detected as the start of the pulse wave component when the decompression is stopped at each stage where the pressure is reduced stepwise. Measuring means;
A second measuring means for measuring the magnitude of the provisional pulse wave riding on the rebound component;
Correction means for correcting the magnitude of the provisional pulse wave measured by the second measurement means based on the increase;
A sphygmomanometer comprising: a blood pressure determination unit that calculates a blood pressure value based on a change in the magnitude of a pulse wave; and an output unit that outputs the magnitude of the pulse wave component corrected by the correction unit. The first measurement means uses the difference between the pressure values in the pressure bag at the start and end of the time length T as the increase, and the increase is measured by D and the second measurement means. When the magnitude of the pulse wave component is A and σ is a predetermined constant, the correction means
Ar = A × (1−σ × D)
The sphygmomanometer according to claim 4, wherein the magnitude Ar of the pulse wave component after correction is calculated by the calculation.   5. The sphygmomanometer according to claim 4, wherein the rising component measuring means is a pressure sensor that detects a pressure in the pressurizing air bag and outputs a pressure signal representing the pressure.

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