JP5086328B2 - Electronic blood pressure monitor - Google Patents

Description

  The present invention relates to an electronic sphygmomanometer, and more particularly to an electronic sphygmomanometer that determines whether or not the cuff pressure is a pulse wave component by comparing a reference value with a difference in cuff pressure extracted at a predetermined time.

  An oscillometric electronic sphygmomanometer wraps a cuff around a living body, extracts a pulse wave component superimposed on the cuff pressure from pressure fluctuation in the cuff, calculates a pulse wave amplitude from the extracted pulse wave, The maximum blood pressure and the minimum blood pressure are determined from the amplitude. When extracting the pulse wave component, if noise due to body movement or other causes occurs, the noise is also superimposed on the cuff pressure together with the pulse wave component. It is conceivable to use a filter to remove noise due to such body movement. However, in order to remove minute noise, a high-performance band-pass filter is required, so that the electronic sphygmomanometer becomes expensive.

  Therefore, an electronic sphygmomanometer has been proposed in which minute noise is removed without using a bandpass filter. For example, the cuff pressure in the depressurization process for reducing the cuff pressure is detected, and the difference between the cuff pressures is calculated at an extraction cycle separated by a predetermined number of times among the detected cuff pressures, and the cuff pressure is calculated from the calculated cuff pressure difference. It is determined whether the pressure is increasing or decreasing, and the minimum cuff pressure in the extraction cycle when the cuff pressure is determined to increase is determined as the pulse wave start pressure value. The maximum cuff pressure in the extraction cycle when it is determined that the pressure tends to decrease is taken as the maximum pressure value of the pulse wave, and the difference between the maximum pressure value and the starting pressure value is taken as the pulse wave amplitude. An electronic sphygmomanometer in which noise is removed is known (for example, see Patent Document 1 below).

  By the way, in an oscillometric electronic sphygmomanometer, a living body is compressed with a cuff during operation, and when the time during which the cuff is compressed becomes longer, the portion of the living body around which the cuff is wound (for example, the upper arm) becomes congested, or The subject may feel uncomfortable even if he does not develop congestion. Therefore, attempts have been made to shorten the compression time as much as possible. As one of them, an attempt has been made to increase the pressure reduction rate of the cuff pressure.

Japanese Patent No. 3717009

  However, the electronic sphygmomanometer disclosed in Patent Document 1 has a problem that the pulse wave component cannot be normally extracted when the cuff pressure is reduced.

  This invention eliminates minute noise without using a band-pass filter by detecting a pulse wave component based on the difference in cuff pressure extracted at a predetermined time in order to eliminate the above-mentioned problems caused by the conventional technology. An object of the present invention is to provide an electronic sphygmomanometer that can extract a pulse wave component in accordance with the change even when the cuff pressure fluctuation speed is changed.

  In order to solve the above-described problems and achieve the object, an electronic sphygmomanometer according to claim 1 calculates a difference between cuff pressures separated by a predetermined interval in the process of pressurizing or depressurizing the cuff. In the electronic sphygmomanometer that determines whether or not the pulse wave is by comparing the difference between the cuff pressure and the reference value, the reference value is changed according to the fluctuation speed of the cuff pressure.

  According to a second aspect of the present invention, there is provided an electronic sphygmomanometer comprising a cuff, cuff pressure control means for pressurizing or depressurizing the cuff, cuff pressure detection means for detecting the pressure in the cuff, and the cuff pressure control means. In the process of increasing or decreasing the pressure in the cuff, the difference between the cuff pressures separated by a predetermined interval is calculated, and the difference between the calculated cuff pressure and the reference value is compared with the pulse wave component. An electronic sphygmomanometer comprising: a pulse wave determination unit that determines whether the pressure is a cuff pressure variation rate calculation unit that calculates a variation rate of the cuff pressure based on a detection signal output from the cuff pressure detection unit. And the reference value is changed in accordance with the cuff pressure fluctuation speed calculated by the cuff pressure fluctuation speed calculation means.

  According to a third aspect of the present invention, there is provided the electronic blood pressure monitor according to the second aspect of the invention, wherein the pulse wave determination means is a detection signal that is repeatedly detected by the cuff pressure detection means at a predetermined extraction cycle. Calculating a difference between cuff pressures detected at extraction cycles separated by a predetermined number of times, and comparing the calculated cuff pressure difference with a reference value to determine whether the cuff pressure is a pulse wave component or not. It is characterized by.

  An electronic sphygmomanometer according to a fourth aspect of the invention is the electronic sphygmomanometer according to the third aspect of the invention, wherein the electronic sphygmomanometer extracts a pulse wave component in the process of reducing the pressure in the cuff. The means controls the cuff pressure to be gradually reduced according to the cuff pressure detected by the cuff pressure detecting means.

  An electronic sphygmomanometer according to the invention of claim 5 is the electronic blood pressure monitor according to claim 4, wherein when the setting of the reference value is changed as the cuff pressure is reduced, 1 immediately after the change is made. Only the beat is applied with the reference value before the change.

  The electronic sphygmomanometer according to the invention of claim 6 is the electronic blood pressure monitor according to claim 4, wherein when the setting of the reference value is changed as the cuff pressure is reduced, the predetermined value immediately after the change is made. The feature is that the reference value before the change is applied only for the time.

  Further, in the electronic sphygmomanometer according to the invention of claim 7, in the invention of claim 5 or 6, the reference value before the change is applied after detecting a pulse wave of one beat or more. It is characterized by doing.

The electronic sphygmomanometer according to the present invention includes a cuff, a cuff pressure control unit that pressurizes or depressurizes the inside of the cuff, and a cuff pressure detection unit that detects a pressure in the cuff. In an electronic sphygmomanometer that extracts a pulse wave component in the process of reducing the pressure in the cuff by means and determines a blood pressure value based on the extracted pulse wave component, in the process of reducing the pressure after pressurizing the cuff The cuff pressure control means controls the cuff pressure to be gradually reduced according to the cuff pressure detected by the cuff pressure detecting means.

  According to this invention, it has the cuff pressure fluctuation speed calculation means for calculating the fluctuation speed of the cuff pressure from the detection signal output from the cuff pressure detection means, and the fluctuation of the cuff pressure calculated by the cuff pressure fluctuation speed calculation means. Since the reference value is changed according to the speed, when the fluctuation speed is changed, the reference value required for determination is changed accordingly. Further, by applying the reference value before the change only for one beat or a predetermined time immediately after the change of the reference value, the pulse wave can be detected immediately after the change of the reference value. Accordingly, the pulse wave component can be normally extracted even when the cuff pressure fluctuation speed changes, and as a result, the time required for blood pressure measurement can be shortened.

  According to the electronic sphygmomanometer according to the present invention, even if the fluctuation speed of the cuff pressure is changed, the pulse wave component can be extracted according to the change.

FIG. 1 is a block diagram showing an overall configuration of an electronic blood pressure monitor according to an embodiment of the present invention. FIG. 2 is a chart showing an example of a reference value setting table of the electronic sphygmomanometer according to the embodiment of the present invention. FIG. 3 is a flowchart showing a blood pressure measurement procedure of the electronic sphygmomanometer according to the embodiment of the present invention. FIG. 4 is a flowchart showing a blood pressure measurement procedure of the electronic sphygmomanometer according to the embodiment of the present invention. FIG. 5 is a flowchart showing a blood pressure measurement procedure of the electronic sphygmomanometer according to the embodiment of the present invention. FIG. 6 is a flowchart showing a blood pressure measurement procedure of the electronic sphygmomanometer according to the embodiment of the present invention. FIG. 7 is an explanatory diagram for explaining the pulse wave determination process of the electronic sphygmomanometer according to the embodiment of the present invention.

Explanation of symbols

1 Cuff 2 Cuff pressure detecting means 3 Pressurizing means 4 Depressurizing means 14 Cuff pressure fluctuation speed calculating means 15 Reference value changing means 16 Pulse wave judging means

  Exemplary embodiments of an electronic blood pressure monitor according to the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 1 is a block diagram showing an overall configuration of an electronic blood pressure monitor according to an embodiment of the present invention. As shown in FIG. 1, the electronic sphygmomanometer includes a cuff 1, a cuff pressure detection unit 2, a pressurization unit 3, a decompression unit 4, a display unit 5, an operation unit 6, and a microcomputer (hereinafter referred to as a microcomputer) 7. ing. The cuff 1, the cuff pressure detection means 2, the pressurization means 3 and the decompression means 4 are connected by a tube 8.

  The cuff pressure detecting means 2 detects the pressure of the cuff 1. The cuff pressure detecting means 2 is constituted by a pressure sensor, for example. The pressurizing means 3 pressurizes the cuff 1 based on the output signal of the microcomputer 7. The pressurizing means 3 is constituted by, for example, a pump that sends a fluid such as air (hereinafter simply referred to as air or the like) to the cuff 1.

  The decompression unit 4 reduces the pressure of the cuff 1 based on the output signal of the microcomputer 7. The decompression means 4 is constituted by, for example, an exhaust valve that exhausts air or the like in the cuff 1 at a slow speed and rapidly. The exhaust valve is opened at an opening that allows a slow exhaust when measuring blood pressure, and gradually reduces the cuff 1. Further, the exhaust valve is fully opened at the end of blood pressure measurement, and the cuff 1 is rapidly decompressed. Note that the decompression means 4 may have a configuration including a slow exhaust valve that exhausts air or the like in the cuff 1 at a slow speed, and a quick exhaust valve that exhausts the air quickly.

  The display means 5 displays the maximum blood pressure value and the minimum blood pressure value determined by the microcomputer 7. The display unit 5 includes, for example, a liquid crystal display panel and a control unit that performs display control of the liquid crystal display panel. The display means 5 may be configured to display the pulse rate and time.

  The operating means 6 has various buttons and switches that are operated by the subject during blood pressure measurement. For example, a measurement start button also serving as a power button, a user ID button for inputting a subject identifier, a switch for setting a pressurization value, a memory button for storing a measurement result, and the like are provided. Yes.

  The microcomputer 7 includes pressurization control means 11, pressure reduction control means 12, blood pressure value determination means 13, cuff pressure fluctuation speed calculation means 14, reference value change means 15, and pulse wave determination means 16. These means constituting the microcomputer 7 are realized by the microcomputer 7 executing a blood pressure measurement program. The pressurization control means 11 and the decompression control means 12 constitute a cuff pressure control means.

  The pressurization control means 11 performs drive control of the pump constituting the pressurization means 3 based on the pressure value of the cuff 1 detected by the cuff pressure detection means 2. For example, when the pressure of the cuff 1 reaches a predetermined pressure during the pressurization of the cuff 1, the pressurization control unit 11 stops the pump. The cuff pressure fluctuation speed calculation means 14 calculates the cuff pressure reduction speed based on the cuff pressure detection signal output from the cuff pressure detection means 2.

  After the pressurization of the cuff 1 is completed, the decompression control means 12 opens the exhaust valve and exhausts air or the like from the cuff 1 at a low speed. At that time, the pressure reduction control means 12 controls the opening degree of the exhaust valve so that the pressure reduction speed calculated by the cuff pressure fluctuation speed calculation means 14 becomes the target pressure reduction speed. In addition, the decompression control means 12 fully opens the exhaust valve in response to the notification from the blood pressure value determination means 13 at the end of blood pressure measurement.

  The reference value changing unit 15 converts the cuff pressure into a pulse wave component based on the decompression speed calculated by the cuff pressure fluctuation speed calculating unit 14 based on, for example, a reference value setting table (see FIG. 2) as described later. The reference value for determining whether or not is is changed. This reference value setting table may be stored in a non-volatile memory built in the microcomputer 7 or may be described in a blood pressure measurement program executed by the microcomputer 7.

  The pulse wave determination means 16 calculates the difference between the cuff pressures detected in the extraction cycle separated by a predetermined number of times among the detection signals repeatedly detected by the cuff pressure detection means 2 in the predetermined extraction cycle when the cuff 1 is decelerated at a slow speed. To do. For example, the cuff pressure detection means 2 repeatedly detects the cuff pressure with an extraction cycle of 10 ms, and the pulse wave determination means 16 detects with an extraction cycle five times apart from the cuff pressure detection signal detected every 10 ms. Calculate the difference in the cuff pressure. In this case, the pulse wave determination means 16 calculates the difference between two cuff pressures detected 50 ms apart every 10 ms.

  The pulse wave determination means 16 determines whether or not the cuff pressure is a pulse wave component by comparing the calculated difference in cuff pressure with the reference value. At that time, when the reference value is changed after detecting the pulse wave of 1 beat or more, the pulse wave determination means 16 applies the reference value before the change only for one beat immediately after the change, The pulse wave component is determined.

  Based on the pulse wave component detected by the pulse wave determination unit 16, the blood pressure value determination unit 13 determines a maximum blood pressure value and a minimum blood pressure value by, for example, a blood pressure determination algorithm based on a known oscillometric method. The determined blood pressure value is displayed on the display means 5. Further, when the blood pressure value determining means 13 determines the blood pressure value, the blood pressure value determining means 13 notifies the decompression control means 12 of the end of measurement in order to open the exhaust valve.

  FIG. 2 is a chart showing an example of the reference value setting table. As shown in FIG. 2, although not particularly limited, for example, the reference value when the pressure reduction speed of the cuff 1 is 7.2 mmHg / s or more is -0.2 mmHg. The reference value when the pressure reduction speed of the cuff 1 is less than 7.2 mmHg / s and 5.0 mmHg / s or more is −0.1 mmHg. The reference value when the pressure reduction speed of the cuff 1 is less than 5.0 mmHg / s is 0.0 mmHg. Note that the critical value of the decompression speed and the reference value when setting the reference value are not limited to the values shown in FIG. 2, and the reference value may be divided into two stages or four or more stages.

  3 to 6 are flowcharts showing the blood pressure measurement procedure of the electronic sphygmomanometer according to the embodiment of the present invention. FIG. 7 is an explanatory diagram for explaining the pulse wave determination process of the electronic sphygmomanometer according to the embodiment of the present invention. Here, an example will be described in which the cuff pressure extraction cycle is 10 ms, and the difference between the cuff pressures detected at five extraction cycles is calculated. As shown in FIG. 3, when the cuff 1 is wound around the upper arm or the like of the subject and the measurement start button or the like of the operation means 6 is operated by the subject to start the blood pressure measurement process, first, the pressurization control means 11 The pressurizing unit 3 is driven to start pressurizing the cuff 1 (step S1).

  Then, it is determined whether or not the pressure of the cuff 1 has reached the pressurization stop pressure value (step S2). If the pressurization stop pressure value is not reached (step S2: No), the pressurization control means 11 continues to pressurize the cuff 1 by the pressurization means 3. If the pressurization stop pressure value is reached (step S2: Yes), the pressurization control unit 11 ends the pressurization by the pressurization unit 3 (step S3).

  Next, the pulse wave determination means 16 resets the pulse wave recognition flag J, the initial pulse wave flag FW, and the pressure reduction speed change pulse wave flag F, and sets all of them to zero. Further, the pulse wave determination means 16 sets the counter value C to 0, and stores the data of the cuff pressure detected by the cuff pressure detection means 2 (0), memory (1), memory (2), The memory (3), the memory (4), and the memory (5) are reset (step S4). These flags, counters, and memory are provided in the microcomputer 7.

  Next, the cuff pressure fluctuation speed calculation means 14 calculates the current pressure reduction speed VP from the pressurization stop pressure (cuff pressure P). The reference value changing means 15 calculates a reference value SP and a pulse end determination reference value SE corresponding to the current decompression speed VP. Here, the values of VP, SP, and SE are provisional values. Then, the decompression control unit 12 starts decompression by the decompression unit 4. At the same time, the pulse wave determination means 16 starts the value t1 of the decompression timer from 0 (step S5). This decompression timer is provided in the microcomputer 7.

  Next, the pulse wave determination means 16 determines whether or not 10 ms (extraction period) has elapsed based on the value t1 of the decompression timer (step S6). If 10 ms does not elapse (step S6: No), the process waits until elapses. When 10 ms has elapsed (step S6: Yes), the cuff pressure detecting means 2 detects the cuff pressure P (step S7). Next, the cuff pressure fluctuation speed calculation means 14 calculates a target pressure reduction speed V from the cuff pressure P by a known method (step S8). The exhaust valve that is the pressure reducing means 4 can be finely controlled when the pressure of the cuff 1 is high, but fine control becomes difficult as the pressure of the cuff 1 becomes low. This is because when the pressure of the cuff 1 becomes low, air or the like in the cuff 1 is not discharged as expected from the cuff 1 no matter how much the exhaust valve is opened. For this reason, the decompression control means 12 of the present invention is divided into three areas: (1) less than 50 mmHg, (2) 50 mmHg or more and less than 150 mmHg, and (3) 150 mmHg or more. Therefore, the target pressure reduction speed V of the cuff 1 is calculated. As described above, fine control is possible when the pressure of the cuff 1 is high, but fine pressure reduction control cannot be performed when the pressure of the cuff 1 is low. Therefore, the pressure reduction control means 12 is a region where the pressure of the cuff 1 is high. When in (3), the decompression speed is controlled to be fast and constant, and when the pressure of the cuff 1 is in the low pressure region (1), the decompression speed is slow and constant. To control. On the other hand, when the pressure of the cuff 1 is in the region (2), the pressure is controlled so as to be a continuous function decompression speed such that the decompression speed becomes slower as the pressure becomes lower. Therefore, at the time of blood pressure measurement, the pressure reduction speed of the cuff 1 is controlled so as to gradually decrease.

  Next, the cuff pressure fluctuation speed calculation means 14 calculates the current pressure reduction speed VP from the detected cuff pressure P. (Step S9). Then, the reference value changing means 15 calculates the reference value S and the pulse end determination reference value SE from the pressure reduction speed V obtained in step S8 (step S10). Further, the pulse wave determination means 16 determines whether or not the reference value S obtained in step S10 is not equal to the current reference value SP (step S11). In step S10, the reference value S may be calculated using the current decompression speed VP.

  If S and SP are equal (step S11: No), the process proceeds to step S13. If S and SP are not equal (step S11: Yes), the pulse wave determination means 16 sets the current reference value SP as the reference value SB before the change, and newly sets the reference value S obtained in step S10 as the current reference value. SP is set, and the value of the pressure reduction speed change pulse wave flag F is set to 1 (step S12). Then, the process proceeds to step S13. In Step S13, the decompression control means 12 performs decompression control of the cuff 1 so that the current decompression speed VP becomes the decompression speed V obtained in Step 8, and the process proceeds to Step S14.

  In step S14, the pulse wave determination means 16 sequentially shifts the data stored in the memory (0), the memory (1), the memory (2), the memory (3), and the memory (4) to obtain the memory (1 ), The memory (2), the memory (3), the memory (4), and the memory (5) (step S14). Next, the pulse wave determination means 16 stores the data of the cuff pressure P detected in step S7 in the memory (0) (step S15).

  Next, the pulse wave determination means 16 determines whether or not the data stored in the memory (5) is not 0 (step S16). If the stored data in the memory (5) is 0 (step S16: No), the extraction timing of the sixth cuff pressure has not been reached after the start of the pressure reduction of the cuff 1, and the process returns to step S6. If the stored data in the memory (5) is not 0 (step S16: Yes), the pulse wave determination means 16 has a value of the pressure reduction speed change pulse wave flag F of 1 and a value of the initial pulse wave flag FW of 1. It is determined whether or not 1 (step S17). In the case of the initial pulse wave, the reference value before the change may not exist, so the latest reference value SP calculated in step S10 is set as the final reference value SC. For this reason, whether or not the pulse wave is the initial pulse wave is added to the determination in step S17.

  If both the values of F and FW are 1 (step S17: Yes), the pulse wave determination means 16 sets the reference value SB before the change as the final reference value SC (step S18), If at least one of the values is 0 (step S17: No), the current reference value SP is set as the final reference value SC (step S19). When the final reference value SC is determined, the pulse wave determination means 16 subtracts the cuff pressure data stored in the memory (5) from the cuff pressure data stored in the memory (0), Is set to X (step S20).

  Next, the pulse wave determination means 16 determines whether or not X calculated in step S20 is larger than the final reference value SC (step S21). If X is SC or less (step S21: No), the process proceeds to step S30. If X is larger than SC (step S21: Yes), the process proceeds to step S22. In the example shown in FIG. 7, the line segment indicated by M1 is a case where X is larger than SC.

  Here, in FIG. 7, white circles indicate the cuff pressure detected by the cuff pressure detection means 2 at every predetermined extraction cycle (10 ms). Further, each line segment indicated by M1, M2, M3, M4, and M10 connects the storage data (the right end of the line segment) of the memory (0) and the storage data (the left end of the line segment) of the memory (5) in each extraction cycle. It is a line segment. Both X and SC are negative values with reference to PS (see FIG. 7). PS is the pressure at the start of the pulse.

  In step S22, the pulse wave determination means 16 determines whether or not the counter value C is 0 (step S22). This counter counts the number of times when X is larger than SC (in the case of Yes) in step S21. If C is not 0 (step S22: No), the process proceeds to step S24. If C is 0 (step S22: Yes), the pulse wave determination means 16 uses the stored data in the memory (5) as the pressure PS at the start point of the pulse. Further, the pulse wave determination means 16 calculates the time ts at the start point of the pulse by subtracting 50 ms from the value t1 of the decompression timer. Then, the pulse wave determination means 16 sets the maximum value Hmax of the pulse wave height H at this time to 0 (step S23), and proceeds to step S24.

In step S24, the pulse wave determination means 16 calculates a pulse wave height H. The pulse wave height H is obtained by the following equation (see FIG. 7).
H = [stored value of memory (0)] − {PS− (t1−ts) · V}

  Next, the pulse wave determination means 16 determines whether or not the pulse wave height H calculated in step S24 is larger than the maximum value Hmax of the pulse wave height (step S25). If H is equal to or lower than Hmax (step S25: No), the process proceeds to step S27. If H is larger than Hmax (step S25: Yes), the pulse wave determination means 16 updates the maximum value Hmax of the pulse wave height with the pulse wave height H (step S26), and proceeds to step S27.

  In step S27, the pulse wave determination means 16 increments the counter value C to C + 1 (step S27). Next, the pulse wave determination means 16 determines whether or not the counter value C is equal to or greater than a predetermined value B (step S28). The value of B may be set according to the blood pressure of the subject. For example, the value of B may be 2 for people with low blood pressure and 4 for people with normal blood pressure.

  If C is smaller than B (step S28: No), the process returns to step S6. If C is B or more (step S28: Yes), the pulse wave determination means 16 recognizes as a pulse and sets the value of the pulse wave recognition flag J to 1 (step S29). Then, the process returns to step S6.

  In step S21, if X calculated in step S20 is equal to or smaller than the final reference value SC (step S21: No), the process proceeds to step S30. In step S30, the pulse wave determination means 16 determines whether X is equal to or less than the pulse end determination reference value SE (step S30). If X is larger than SE (step S30: No), the pulse wave determination means 16 determines whether or not the value of the pulse wave recognition flag J is 1 (step S31). If the value of J is 0 (step S31: No), the pulse wave determination means 16 sets the counter value C to 0 (step S33) and returns to step S6. If the value of J is 1 (step S31: Yes), the process proceeds to step S24.

  On the other hand, if X is less than or equal to SE in step S30 (step S30: Yes), the pulse wave determination means 16 determines whether or not the value of the pulse wave recognition flag J is 1 (step S32). In the example shown in FIG. 7, the line segment indicated by M10 is a case where X is SE or less. If the value of J is 0 (step S32: No), the pulse wave determination means 16 sets the counter value C to 0 (step S33) and returns to step S6. If the value of J is 1 (step S32: Yes), the maximum value Hmax of the pulse wave height at this time is stored in the memory (step S34). Hmax at this time becomes the pulse wave height of the current pulse.

  Next, the pulse wave determination means 16 sets the value of the pulse wave recognition flag J and the pressure reduction speed change pulse wave flag F to 0, and sets the value of the initial pulse wave flag FW to 1. Moreover, the pulse wave determination means 16 resets the value C of the counter to 0 and resets the memory (0) to memory (5) (step S35). Next, the blood pressure value determination means 13 performs blood pressure measurement by a known blood pressure determination algorithm, and calculates a maximum blood pressure value and a minimum blood pressure value (step S36).

  Next, the blood pressure value determining unit 13 determines whether or not the minimum blood pressure value has been calculated (step S37). When the minimum blood pressure value cannot be calculated (step S37: No), the process returns to step S6. When the minimum blood pressure value can be calculated (step S37: Yes), the blood pressure value determination unit 13 displays the maximum blood pressure value and the minimum blood pressure value on the display unit 5 (step S38), and the blood pressure measurement is terminated.

  In the above-described embodiment, when the pulse wave component is determined, the reference value before the change is applied only to one beat immediately after the change of the reference value. The reference value before the change may be applied only for a predetermined time immediately after the change. That is, when the setting of the reference value is changed after detecting a pulse wave of one or more beats, the pulse wave determination unit 16 applies the reference value before the change only for a predetermined time immediately after the change.

  In this case, in the description of the flowchart described above, it is added in step S12 that the pulse wave determination unit 16 starts the value t2 of the pressure reduction speed change timer from 0. The decompression speed change timer is provided in the microcomputer 7. In step S17, the pulse wave determination means 16 determines whether or not the value t2 of the pressure reduction speed change timer is smaller than the predetermined value A and the value of the initial pulse wave flag FW is 1. If t2 is smaller than A and the value of FW is 1 (Yes at Step S17), the pulse wave determination means 16 proceeds to Step S18, where t2 is greater than or equal to A or If the value is 0 (step S17: No), the process proceeds to step S19. The processing of each other step is as described above.

  As described above, according to the embodiment, the reference value is changed according to the pressure reduction rate of the cuff pressure calculated by the cuff pressure fluctuation rate calculation means 14, so that when the pressure reduction rate is changed, the reference value is changed accordingly. The reference value used for determination is changed. Therefore, the pulse wave component can be extracted normally. Conventionally, the pulse wave may not be detected immediately after the change of the reference value. However, by applying the reference value before the change only for one beat or a predetermined time immediately after the change of the reference value, The pulse wave can be detected immediately after the change. As described above, the present invention is not limited to the above-described embodiment, and various modifications can be made. For example, it may be an electronic sphygmomanometer that extracts a pulse wave component and determines blood pressure in the process of increasing the pressure in the cuff.

  As described above, the electronic sphygmomanometer according to the present invention is useful for an electronic sphygmomanometer that removes minute noise without using a band-pass filter, and in particular, based on a difference in cuff pressure extracted at a predetermined time. It is suitable for an electronic blood pressure monitor having a function of detecting a pulse wave component.

Claims (7)

An electronic sphygmomanometer that determines a pulse wave by calculating a difference between cuff pressures separated by a predetermined interval and comparing the calculated difference between the cuff pressure and a reference value in the process of pressurizing or depressurizing the cuff In
An electronic sphygmomanometer, characterized in that the reference value is changed according to the fluctuation speed of the cuff pressure. In the process of increasing or decreasing the pressure in the cuff by the cuff, the cuff pressure control means for pressurizing or depressurizing the cuff, the cuff pressure detecting means for detecting the pressure in the cuff, and the cuff pressure control means Calculating a difference between cuff pressures separated by a predetermined interval, and comparing the calculated cuff pressure difference with a reference value to determine whether the cuff pressure is a pulse wave component; In an electronic sphygmomanometer comprising:
A cuff pressure fluctuation speed calculating means for calculating a fluctuation speed of the cuff pressure based on a detection signal output from the cuff pressure detecting means, and according to the fluctuation speed of the cuff pressure calculated by the cuff pressure fluctuation speed calculating means. And changing the reference value.   The pulse wave determination means calculates a difference between cuff pressures detected in extraction cycles separated by a predetermined number of times among detection signals repeatedly detected by the cuff pressure detection means in a predetermined extraction cycle, and the calculated cuff pressure is calculated. 3. The electronic sphygmomanometer according to claim 2, wherein it is determined whether or not the cuff pressure is a pulse wave component by comparing the difference in pressure with a reference value.   An electronic sphygmomanometer that extracts a pulse wave component in the process of reducing the pressure in the cuff, wherein the cuff pressure control means is configured to reduce the cuff pressure according to the cuff pressure detected by the cuff pressure detection means. The electronic sphygmomanometer according to claim 3, wherein the electronic sphygmomanometer is controlled so as to be gradually delayed.   5. The reference value before the change is applied only to one beat immediately after the change when the reference value is changed as the cuff pressure is reduced. The electronic sphygmomanometer described in 1.   5. The reference value before the change is applied only for a predetermined time immediately after the change when the setting of the reference value is changed as the cuff pressure is reduced. The electronic sphygmomanometer described in 1.   The electronic sphygmomanometer according to claim 5 or 6, wherein the reference value before the change is applied after detecting a pulse wave of one or more beats.

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