JPS6145729A - Digital hemomanometer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a non-invasive digital sphygmomanometer, and in particular, when the pressure applied to the cuff is gradually reduced, the pressure generated within the cuff due to the expansion and contraction movement of the diameter of the blood vessel. This invention relates to a digital sphygmomanometer that uses a pressure sensor to detect disappearing pulse pressure oscillations and determines a subject's blood pressure based on this.

[Prior Art and its Problems] Conventionally, non-invasive digital blood pressure monitors have generally been based on automatic recognition of Korotkoff sounds.

By the way, with this type of device, it is necessary to recognize the appearance and disappearance of Korotkoff sounds without relying on humans, but since the volume is very weak, it is difficult to recognize when the cuff pressure is controlled or when the subject moves his arm. This makes blood pressure measurement difficult, as it is susceptible to friction noise between the microphone and the skin that occurs when the blood pressure is applied. In addition, in order to eliminate the influence of such noise, we use a pressure sensor to detect pulse pressure oscillations that occur and disappear within the cuff due to the expansion and contraction movement of the blood vessel diameter when gradually decreasing the pressure applied to the cuff, without relying on Korotkoff sounds. Attempts have been made to measure blood pressure using the so-called oscillometric method, in which blood pressure is determined based on an amplitude locus curve obtained by plotting the amplitude of the detected pulse pressure oscillation signal. However, blood pressure measurement using the oscillometric method requires a huge amount of pulse pressure vibration signal data because the systolic blood pressure and diastolic blood pressure are determined by analyzing the amplitude trajectory curve. Therefore, when this is done using digital information processing means, a considerable amount of data must be stored in the Iλ memory.
Conventional devices have been large and expensive.

[Object of the Invention] The present invention has been made in view of the above-mentioned drawbacks of the prior art, and its purpose is to enable blood pressure measurement by the oscillometric method even with a small capacity memory. Our objective is to provide a small and lightweight digital blood pressure monitor. Also preferably.

An object of the present invention is to provide a digital blood pressure monitor whose main part is entirely composed of a single-chip digital LSI.

[Summary of the invention] In order to achieve the above object, the digital blood pressure monitor of the present invention has the following features:
a measuring means for converting the detected cuff pressure into an electrical digital signal when it is time to gradually reduce the pressure applied to the cuff;
In a digital sphygmomanometer comprising an information processing means for processing a series of digital signals output from the measuring means to determine blood pressure, the information processing means detects the pulse generated at the pulse pressure vibrating portion of the blood vessel from the series of digital signals. A data extraction means for extracting the data of the pressure vibration signal, and as the measurement progresses, first, only the data of the part useful for determining the systolic blood pressure is stored in a memory, and then the data of the pulse pressure vibration signal output from the data extraction means is stored in a memory. The outline of the method is to include a window means for storing in the memory only data useful for determining the blood pressure, and a blood pressure determination means for determining the blood pressure based on the data read from the memory.

Preferably, the data extraction means starts extracting data of the pulse pressure oscillation signal upon detecting a digital signal showing a different change from a series of digital signal values showing a change of a substantially constant slope due to cuff decompression. is one aspect of this.

Still more preferably, one aspect of the data extraction means is to extract data of a pulse pressure vibration signal corresponding to a peak of an amplitude signal obtained by subtracting a value corresponding to cuff decompression from the pulse pressure vibration signal.

Still further preferably, the window means is arranged such that the amplitude of the pulse pressure oscillation signal minus a value corresponding to a cuff decompression shows an increase in amplitude, while the amplitude of the pulse pressure oscillation signal is less than the value determined according to the amplitude of the most recent amplitude signal. One aspect of this is to erase data of past pulse pressure oscillation signals having a oscillation signal from the memory.

Still preferably, the window means is determined according to the maximum amplitude of the past amplitude signal during which the amplitude of the pulse pressure oscillation signal minus a value corresponding to cuff decompression shows a decrease after an increase. One aspect of this is not storing data of the latest pulse pressure vibration signal having an amplitude smaller than the value in the memory.

[Embodiment of the Invention] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing a digital blood pressure monitor according to an embodiment of the present invention. In the figure, 1 is a measurement unit that detects the cuff pressure of a cuff (not shown) and converts it into a digital signal, and 2 is a measurement unit that processes the digital signal output from the measurement unit 1 according to a predetermined algorithm. 3 is a data processing unit that determines the systolic blood pressure and diastolic blood pressure of the subject;
a display section that displays the systolic blood pressure value and diastolic blood pressure value determined by the
4 is a buzzer for notifying the subject of the completion of the measurement, etc.

The measurement unit 1 inputs the cuff pressure led from the cuff through a pipe,
A pressure quadrature transducer 5 that directly converts the cuff pressure including pulse pressure vibration into an electrical signal, an oscillator 6 that oscillates at a frequency according to the output signal of the pressure quadrature transducer 5, and an oscillator 6.
The frequency counter 7 counts the oscillation frequency of the oscillation frequency.

The data processing unit 2 includes a ROM containing a program, a RAM necessary for data processing, and a P for inputting and outputting processing data.
It consists of a central processing unit (CPU) housed in a chip along with IO, etc., and various functional blocks of the CPU realized by executing the program are shown in the blocks of the data processing unit 2. has been done. To briefly explain these functional blocks, 8 is a data input unit that samples and inputs the digital signal output from the measurement unit l at predetermined intervals, and 9 is data of the pulse pressure oscillation portion of the sampling input data that is useful for blood pressure determination. 10 is a time generation section that generates time information necessary for pulse pressure oscillation measurement and data processing based on the pulse pressure vibration measurement; 11;
12 is a memory for storing pulse pressure vibration data useful for blood pressure determination from the data extraction unit 9, and 12 is a memory 11 with limited capacity.
In order to effectively use the pulse pressure oscillation measurement, a window control unit that moves the range of data to be focused on as pulse pressure oscillation measurement progresses;
Reference numeral 3 denotes a blood pressure determination unit that analyzes the trajectory drawn by each peak value of the pulse pressure vibration data within the window and determines the systolic blood pressure and diastolic blood pressure of the subject.

Now, various pressure cadence transducers can be used in the measuring section 1 of the embodiment. Examples include a semiconductor strain gauge type, a wire strain gauge type, a differential transformer type, and a capacitance type. However, in consideration of ease of electrical handling, ease of obtaining high frequency and highly stable oscillation characteristics in the oscillator 6, cost, etc., a capacitance type is preferable. FIG. 2(A) is a diagram showing a specific example 1' in which a capacitance turgor quadrangle transducer is used in the measuring section (2). In the figure, fluctuations in the cuff pressure led from the cuff through a pipe give displacement to the diaphragm D of the pressure transducer 5', and as the cuff pressure increases, the capacitance of the capacitor C, which is linked to this displacement, decreases and the cuff pressure increases. When it decreases, it works to increase the capacity. The pulse oscillator 6', which uses the capacitance as a frequency determining element, is activated when a timing gate signal TG with a predetermined time width applied via a line 101 is turned on.
oscillates at a frequency that is inversely proportional to the capacitance.

Such an oscillator 6' can be realized with an extremely simple configuration including a digital inverter circuit. Similarly, the frequency counter 7' counts the oscillation clock signal CLK output from the pulse oscillator 6' while the timing gate signal TG is ON, and when the timing gate signal TG is turned OFF, it holds the count value P at that point, and 71. Second
Figure (B) is a timing chart showing the above-mentioned operation of the measuring section 1'. As shown in the figure, when the cuff pressure changes from decreasing to increasing, the frequency of the oscillation clock signal CLK also changes from decreasing to increasing in proportion to this. The timing gate signal TG is, for example, 5 ms from the time generator 10.
The frequency counter 7' outputs the oscillation clock signal CLK while the timing gate signal TG is ON.
count the number of pulses, and as a result, count values P1 and P2 according to the cuff pressure at each gate timing,
Output to line 71. For example, in the device of this embodiment, when the cuff pressure is 100.0 mmHg, the count value is 1000,
It is configured such that the count value becomes 1014 when the cuff pressure is 1.4 mmHg (7), and the count value above the tens digit is displayed as is on the display section 3.

FIG. 2(C) is a diagram showing another embodiment 1'' of the measurement unit l. Structures equivalent to those in FIG. Oscillator 6″
always oscillates at a frequency that is inversely proportional to the capacitance of the capacitor C which is linked to the displacement of the diaphragm D. On the other hand, the period counter 7'' receives lines 101 and 1 from the time generator 10.
03, a timing gate signal TG and a high frequency basic clock signal SCK are applied. The period counter 7″ is
While the timing gate signal TG is ON, the pulse oscillator 6
``Count the basic clock signal SCK from the rising edge to the rising edge of the output oscillation clock signal CLK, and hold the count value P' of the period counted several times until the timing gate signal TG is turned OFF each time.
Output to. FIG. 2(D) is a timing chart showing the above-mentioned operation of the measuring section 1''.As shown in the figure, as the cuff pressure increases from decreasing to increasing, the frequency of the oscillation clock signal CLK also decreases in proportion to this. In this case, the timing gate signal TG is output from the time generator 10 at a period of, for example, 2 ms, and the period counter 7'' calculates the oscillation clock signal CLK while each timing gate signal TG is ON. The basic clock signal SCK from rising to rising is counted, and as a result, a count value Pl that is inversely proportional to the cuff pressure at each gate timing is set.
'+P2'+... is counted and output to line 71. The data input unit 8 takes the average of these count values P1 ′+ P2 ′+ . The advantage of this method is that the cuff pressure can be sampled with sufficient density even when, for example, a high frequency is not desired for the oscillating clock signal CLK.

The operation of the above configuration will be explained below. Third
The figure shows the relationship between cuff pressure applied to a cuff and blood pressure. Wrap the cuff around your upper arm as is commonly practiced15
When the cuff pressure is increased to 0 to 200 mmHg and then gradually reduced, the pulse pressure oscillation that occurs within the cuff and disappears due to the relationship between the pulse pressure movement of the blood vessels and the applied cuff pressure is around the subject's systolic blood pressure. The amplitude suddenly increases at 300°C, and the amplitude suddenly slows down near the diastolic blood pressure. According to this embodiment, the measuring unit 1' shown in FIG. 2(A) directly converts this pulse pressure vibration into an electrical signal to obtain a count value P proportional to the cuff pressure. The waveform plotted along the axis becomes a cuff pressure detection signal V in which pulse pressure oscillations that appear and disappear as the cuff pressure decreases at a constant rate are superimposed, as shown in FIG.

The data processing unit 2 of the embodiment analyzes this cuff pressure detection signal V to determine the systolic blood pressure and diastolic blood pressure of the subject, which is also referred to as the so-called oscillometric method. This operation will be described below with reference to FIG. 1. First, the count value P output from the measuring section 1 is sampled into the data input section 8 and sent to the data extraction section 9. The data extraction section 9 is a section that extracts data of a pulse pressure oscillation part useful for blood pressure determination from input data, and a specific method thereof is shown in FIG. Generally, the cuff pressure applied to the arm cuff is 2 to 4 m.
Since the pressure is reduced at a rate of mHg/sec, the cuff pressure detection signal V in the portion where there is no pulse pressure fluctuation exhibits a constant falling characteristic proportional to this pressure reduction rate. That is, if the count value sampled at a certain time ti is Pl and the count value sampled at the next time Lm is Pm, then the difference between Pl and Pm at a predetermined sampling interval (5 ms) should be within a substantially constant range. . The data extractor 9 removes data whose difference is within a certain range, since this data is not necessary for blood pressure determination to be performed later. In the illustrated example, the data extraction unit 9 removes data PJI after comparing and determining the sizes of data Pi and Pm. The same applies to similar sampling data groups preceding data Pl.

However, considering the convenience of [equipment use], especially 150 to 2
It is desirable that the subject be able to read changes in the cuff pressure via the display unit 3 until the measurement start point where the pressure is gradually reduced after the cuff pressure is increased to 00 mmHg. Therefore, sampling data in this section is extracted at appropriate intervals, and the window control unit 12 and blood pressure determination unit 13
is sent to the display unit 3 via the display unit 3 and displayed.

Now, the data extractor 9 receives the sampling data Pn at the next time tn. And this data Pn and P
By comparing the magnitudes of m, it can be determined that the cuff pressure detection signal V has escaped from the above-mentioned constant downward characteristic and has started to rise.

Of course, the above processing involves plotting several consecutive sampling data Pi, Pm, Pn,...
It is clear that even more accurate detection can be obtained if judgment is made by following changes in the slope.

Regarding this point, the same applies below. The data extraction unit 9 determines this as the starting point of pulse pressure oscillation, and the window control unit 12
The sampling data Pm is temporarily stored in the buffer area of the memory 11 via the buffer area of the memory 11.

Subsequently, the magnitude of each sampling data appearing in the pulse pressure oscillation part showed an upper A within a predetermined gradient range starting from the data Pm, turned downward after reaching the peak, and further showed a decline within the predetermined gradient range. The later sampling data r+t is reached. The data extraction unit 9 stores the data in the buffer area of the memory 11 while checking the changes in the data of the two consecutive parts. The sampling data Pu is received at the next point in time. Then, when it is found by comparing the data PL and Pu that the data falls within the range of a certain falling characteristic due to cuff decompression, the sampling data Pu is removed. The same applies to similar sampling data groups subsequent to the data Pu. In this way, the pulse pressure amplitude signals AI, A2, and the portions useful for blood pressure determination are determined from the cuff pressure detection signal V.
...is extracted. Incidentally, time information necessary for processing in the data extracting section 9 is given from a time generating section 10 via a line 102.

Furthermore, the data extraction unit 9 determines other conditions after detecting the above-mentioned pulse pressure amplitude signal. For example, a certain pulse pressure amplitude signal A2
should occur around a predetermined time interval Td determined by the subject's heart rate, etc. from the preceding pulse pressure amplitude signal A1, so it should occur at an extremely shorter time than this time Td or at an extremely longer time. The data of the amplitude signal is usually noise and is removed because it is useless for blood pressure determination. The time interval Td is initially set to a certain value, and when several pulse pressure amplitude signals are detected, the average interval is calculated, etc., and the time interval Td is changed to a value suitable for the subject, approaching a proper value.

Of course, a method using a heartbeat synchronized sound detected through another route may also be used. Also, the preceding pulse pressure amplitude signal A1 or a plurality of pulse pressure amplitude signals A1.

Data of amplitude signals having an extremely large amplitude or an extremely small amplitude compared to A2 are also removed for the same reason.

Furthermore, noise for which the width of the amplitude signal does not exceed a predetermined value is also usually noise, and when it occurs within the above-mentioned - constant falling characteristic of cuff pressure, it is removed, or a valid pulse pressure amplitude signal In this way, the data extraction unit 9 removes the data of the cuff decompression part that shows the known descending characteristics, and when the subject moves his arm, etc. As a result, only pulse pressure amplitude signals useful for blood pressure determination are stored in the memory 11, and a considerable amount of memory space is saved. Note that, after detecting the pulse pressure amplitude signal A, the data extraction section 9 may further extract only data corresponding to a peak therein. This is because by doing so, it is possible to further save memory.

The window control unit 12 manages data writing and reading from the memory 11, and in order to effectively use the memory 11, which has a limited capacity, the window control unit 12 controls the range of noteworthy data (window ) works to move. Since the operation of the window control section 12 is linked to the operation of the blood pressure determination section 13, this point will be explained first with reference to FIG. FIG. 5 is a diagram showing changes in the magnitude of the pulse pressure amplitude signal with respect to the time axis. Now, the pulse pressure amplitude signal A1 in Fig. 4. A1 is the signal obtained by subtracting the descending component based on cuff decompression from +A2...

A2'... If you bind them and arrange them along the time axis, it will look like Figure 5. Then, by plotting the peak values of the signal amplitudes from each pulse pressure amplitude signal AH' to A m ', a locus Y indicating a change in the magnitude of the pulse pressure amplitude signal is obtained. Hereinafter, for convenience of explanation, the pulse pressure amplitude signal will be expressed as Al
′, A2 ′... will be used. The window control unit 12 sequentially stores the data of the pulse pressure amplitude signals A, ′, A2 ′, etc. input as the measurement progresses in the memory 11, and sequentially stores the area (window) W in which valid data is accumulated. Expand it. Then, the size of the window at a certain point in time is Wl. On the other hand, the data of this window control section is also given to the blood pressure determination section 13 via line 121, and the determination section 13 attempts to determine the subject's systolic blood pressure based on this data. As mentioned above, the pulse pressure amplitude signal A□
Since the peak value of +A2'... has the property of showing a sudden increase at the subject's systolic blood pressure, the blood pressure determination unit 13 examines the slope of the trajectory Y, and first determines, for example, point Pa' in the figure as the systolic blood pressure. Then, the systolic blood pressure value m'ax (in the case of an untested example, the count at that time?i) is displayed on the display unit 3 via the line 132.
(P is designed to directly represent the blood pressure value) and hold the display. Further, the window control unit 12 accumulates data of the pulse pressure amplitude signal that is continuously inputted, and widens the size of the window. The window size at the next certain point in time is W2. However, at this point, the blood pressure determination unit 13 again detects a sudden increase in the trajectory Y.
Discover the points. Therefore, the blood pressure determination unit 13 compares the change in the slope near the point Pa' with the change in the slope near the point Pa, checks what is the highest value of the trajectory Y stored up to this point, and further calculates other values. Various conditions, such as whether or not there is a noise-like change in amplitude near point Pa, are determined, and finally it is determined which point is the true systolic blood pressure point. If the Pa point is appropriate, the systolic blood pressure value display on the display section 3 is updated and held. In this way, the blood pressure determination unit 13 can always monitor all data within the window, so it can ultimately make a highly reliable determination.

Line 13 indicates that the blood pressure determination unit 13 has determined the systolic blood pressure point.
The window control unit 12 is also notified via the link 1. When the window control unit 12 learns that a new systolic blood pressure point Pa has been determined, the window control unit 12 no longer has Pa′ in view of its own storage capacity.
If the systolic blood pressure cannot exist in the previous data including the point, that part of the data is deleted from the memory 11. In determining whether to delete data, it is important to know what the highest value of the trajectory Y stored up to this point is. Generally, the value corresponding to the peak of the trajectory Y varies depending on the subject, and has an important meaning for determining the systolic blood pressure using the device of this embodiment. That is, if the peak of the trajectory Y is relatively large, the pulse pressure amplitude signal that indicates the characteristics of the systolic blood pressure point also tends to become large. Therefore, if the pulse pressure amplitude at the Pa' point is sufficiently smaller than the highest value of the trajectory Y stored up to this point, the data up to that portion will be erased from the memory 11. Therefore, the new window size is W2 minus W2'.

The window control unit 12 further continues to accumulate input data,
The size of the window at a certain point in time is wl. On the other hand, at this point, the blood pressure determination unit 13 detects that the trajectory Y changes from an increase to a decrease and further enters a decreasing characteristic portion within a predetermined range, and notifies the window control unit 12 of this via a line 131. By receiving this notification, the window control unit 12 knows that there is no possibility of determining the systolic blood pressure in the future, so it leaves the data corresponding to the peak of the trajectory Y and deletes the data before that from the memory 11. Of course, if the value corresponding to the peak of the trajectory Y is to be stored elsewhere, the data of the portion corresponding to the peak of the trajectory Y may be deleted. This is because the peak value of the trajectory Y has an important meaning for determining the diastolic blood pressure. Therefore, the new window size is Wl minus WJI'.

In fact, when the peak of trajectory Y is detected (recognized),
The data acquisition range shown by the amplitude window FW in Fig. 5 is determined, and for example, the data at the point showing a sudden rise in the trajectory Y near the peak of the trajectory Y shown at point P8 in the same figure is removed, and the amplitude window FW is Let the value indicating the systolic blood pressure value of Wm be the true value.

This is because, depending on the subject, the P8 point, which is an erroneous signal, may be observed near the peak of the trajectory Y, and empirically,
This is achieved by experimentally determining the amplitude window FW by predetermining the ratio of the peak of the trajectory Y to the absolute amplitude value.

The measurement process is further continued, and the window size at a certain point is Wm. The blood pressure determination unit 13 uses this window W.
A point Pb where the descent of the trajectory Y changes from a steep part to a gentle part is detected from the data within m, this point is determined to be the diastolic blood pressure, and the diastolic blood pressure value min is displayed on the display unit 3 via the line 133. send and hold the display. When the measurement process is continued and a point Pb' indicating a new diastolic blood pressure is detected, the trajectory Y is again determined to determine which point is the true diastolic blood pressure.
The ratio to the value corresponding to the peak of is important. That is, in this example, the amplitude of the diastolic blood pressure point Pb' is
If the value is extremely small compared to the peak value of , the diastolic blood pressure determination is not updated. This means that window Wm
The same can be said about the process of expanding . That is, for example, when the size of the data All' newly stored in the window Wm is sufficiently smaller than the peak value of the trajectory Y, it is no longer necessary to store any more data in the memory 11. That's because there isn't. This state is also a requirement for determining the end of measurement, which will be described later. Therefore, blood pressure determination section 13
After displaying the diastolic blood pressure, if the requirements to end the measurement are satisfied, the buzzer 4 sounds via the line 134 to inform the subject that the measurement has ended. In addition, in the double explanation, the window W is expanded due to the accumulation of new pulse pressure amplitude signals, and data that is no longer needed for blood pressure determination is deleted based on a predetermined judgment, so the size of the window W is constant. However, the blood pressure determination unit has the advantage of being able to retrieve necessary data at any time, and has the effect of saving memory, improving the reliability of blood pressure determination.

FIG. 6 is a flowchart showing the main execution procedure of the above-mentioned seating pressure determination process performed in the data processing section 2.

In step S1, the data input section 8 inputs the count value P. In step S2, data extraction processing, which will be described later, is performed. That is, data of a portion showing a constant falling characteristic along the cuff decompression is removed. In step S3, it is determined whether the data extraction unit 9 has extracted a pulse pressure amplitude signal A useful for blood pressure determination. If the determination is NO, the process exits and waits for the next sampling data, and the above-described process is repeated until the pulse pressure amplitude signal A is obtained. Also, the determination in step S3 is Y.
When ES is reached, the process advances to step S4, and the window control unit 12
The pulse pressure amplitude signal A is stored in the memory 11 after the preceding pulse pressure amplitude signal. In step S5, a blood pressure determination meeting display process, which will be described later, is performed. That is, the maximum or minimum blood pressure is determined including the newly accumulated pulse pressure amplitude signal A,
If there is a judgment, the blood pressure will be displayed and held. In step S6, window processing, which will be described later, is performed to erase data unnecessary for blood pressure determination to save memory. In step S7, it is determined whether or not the measurement has ended. When the magnitude of the pulse pressure amplitude signal A stored in the memory 11 in the latter half of the measurement is smaller than the predetermined range compared to the peak value of the trajectory Y, it is determined that the measurement has ended. When the measurement is completed, the process proceeds to step S8 and the buzzer 4 is sounded to notify the subject of the completion of the measurement. If the measurement is not completed, exit the process and wait for the next sampling data.

FIG. 7 is a flowchart showing the data extraction processing procedure. In step S21, it is determined whether the data extraction flag is 6N. At the start of measurement, the data extraction flag is reset by initialization. Therefore, the process proceeds to step S22, and a gradient test of the turnip pressure detection signal (2) is performed.

In step S23, it is determined whether the signal V has changed from a constant downward slope due to cuff decompression to an upward slope within a predetermined range. If the determination is No, the process exits and waits for the next sampling data. When the determination is YES, this point is determined to be the starting point of the pulse pressure amplitude signal A, and step S
At step 24, the sampling data is stored in the buffer area of the memory 11. In step 325, a data extraction flag is turned ON to indicate that the subsequent series of sampling data is a pulse pressure amplitude signal. From the next sampling data, the process proceeds to step 326. In step 326, the input data is stored in the buffer area. In step S27, a gradient test of the cuff pressure detection signal V is performed to detect the rear end of the pulse pressure amplitude signal. In step 328, it is determined whether the steep descending characteristic has changed to a constant descending characteristic due to cuff decompression. If the determination is No, the process exits and the storage continues in the buffer area. Step 3
If the determination in step 28 is YES, it means that the pulse pressure amplitude signal A has been detected. In step S29, the data extraction flag is set to O.
FF, and in step S30, the detected pulse pressure amplitude signal A
The amplitude ratio with the preceding pulse pressure amplitude signal, the pulse interval, etc. are examined. In step S31, it is determined whether the pulse pressure amplitude signal A is a noise signal as a result of the test. When it is determined that the signal is a noise signal, the process advances to step S32 and the buffer area is cleared. If it is not a noise signal, the process proceeds to step 333 and the pulse pressure amplitude signal detection flag is turned on.

FIG. 8 is a flowchart showing the blood pressure determination/display processing procedure. In step S51, it is determined whether the mode is diastolic blood pressure determination mode. Since the systolic blood pressure is determined at the start of measurement, the determination is NO. The process proceeds to step S52, and the upward slope of the trajectory Y is inspected. In step 353, it is determined whether or not the trajectory Y has a feature point that indicates systolic blood pressure. If there is a feature point, the display of the systolic blood pressure value is held in step S54, and the systolic blood pressure determination flag is turned on in step S55. The flag is used to determine whether or not the window processing unit 12 can execute data deletion. Further, if there is no feature point in the determination in step S53, step S5
Skip steps 4 and 355. In step 356, the peak slope of trajectory Y is examined. In step 357, it is determined whether the trajectory Y has changed from rising to falling. When the determination is YES, the process proceeds to step 358, where the diastolic blood pressure determination mode is turned on, and the peak determination flag is turned on in step S59. Further, if the determination in step S57 is that the slope is not the peak slope, the processes in steps S58 and 359 are skipped. Next, after the diastolic blood pressure determination (flag) mode is turned on, the process advances to step S60. In step S60, the downward slope of the trajectory Y is examined, and in step S61, it is determined whether the downward slope has changed from a steep downward slope to a gentle downward slope.

If the determination is YES, the process proceeds to step 362, where the diastolic blood pressure value is displayed and held, and the diastolic blood pressure determination flag is turned ON in step S63. Also, the determination in step 361 is NO.
In this case, the processes of steps S62 and 863 are skipped.

FIG. 9 is a flowchart showing the window processing procedure. In step 371, it is determined whether the systolic blood pressure determination flag is ON or not. If YES, the process advances to step S72 and the systolic blood pressure determination flag is turned OFF. In step S73, it is determined whether there is any preceding pulse pressure amplitude data that may be deleted, and if YES, the corresponding data is deleted in step S374. If there is no data that can be erased, the process of step 374 is skipped. Also, step S71
If the systolic blood pressure determination flag is not ON in step S75, it is determined whether the peak determination flag is ON. When the peak determination flag is ON, the peak determination flag is turned OFF in step 376, and data unnecessary for diastolic blood pressure determination is deleted in step S77. Furthermore, if the peak determination flag is not ON in step S75, it is determined in step 378 whether the diastolic blood pressure determination flag is ON. When the diastolic blood pressure determination flag is ON, step S7
Step 9 turns the diastolic blood pressure determination flag OFF. Step S8
If 0, it is determined whether there is any preceding pulse pressure amplitude data that may be deleted, and if YES, the corresponding data is deleted in step 581. If there is no data that can be erased, the process of step S81 is skipped. Furthermore, if the diastolic blood pressure determination flag is not ON in the determination at step 378, the process directly advances to step S82. In step S82, the magnitude of the peak value of the trajectory Y and the latest input value of the pulse pressure amplitude signal is compared, and in step S83, it is determined whether the magnitude of the pulse pressure amplitude signal is smaller than a predetermined range. If it is smaller, the process advances to step 84 and the measurement end flag is turned on. Also, if it is not small, the process exits as is.

In the above-mentioned embodiment, the measurement section 1 and the data processing section 2 were explained separately, but in reality, the main meter side section 1 can be constructed entirely of digital circuits except for the pressure transducer 5. 1 chip LSI along with processing section 2
It is clear that it can be composed of

[Effects of the Invention] As described above, according to the present invention, the amount of sampling data stored in the memory is significantly reduced, so the entire device can be made smaller, and a handy and high-performance device that uses batteries or the like as a power source can be realized. Digital blood pressure monitors can be provided at low prices.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram showing a digital blood pressure monitor according to an embodiment of the present invention, FIG. (B) is a timing chart showing the operation of FIG. 2(A), FIG. 2(C) is a diagram showing another embodiment of the measurement unit 1, and FIG. 2(D) is a timing chart showing the operation of FIG. 2(C). Timing chart I showing the operation, Figure 3 is a diagram showing the relationship between cuff pressure applied to the cuff and blood pressure, and Figure 4 is a method for extracting pulse pressure oscillation data useful for blood pressure determination from input data. 5 is a diagram showing changes in the magnitude of the pulse pressure amplitude signal with respect to the time axis. FIG. 6 is a flowchart showing the main execution procedure of the blood pressure determination process performed in the data processing section. FIG. 8 is a flowchart showing the extraction processing procedure, FIG. 8 is a flowchart showing the blood pressure determination/display processing procedure, and FIG. 9 is a flowchart showing the window processing procedure. Here, 1... measurement section, 2... data processing section, 3.
...Display section, 4...Buzzer, 5...Pressure transducer, 6...Oscillator, 7...Frequency counter, 8
...Data input section, 9...Data extraction section, 10...
- Time generating unit, 11... memory, 12... window control unit, 13... blood pressure determination unit.

Claims (5)

[Claims] (1) A measuring means that converts the detected cuff pressure into an electrical digital signal when gradually decreasing the pressure applied to the cuff, and information processing that processes a series of digital signals output from the measuring means to determine blood pressure. In the digital sphygmomanometer, the information processing means includes data extraction means for extracting data of a pulse pressure vibration signal generated in a pulse pressure vibration portion of a blood vessel from the series of digital signals, Regarding the signal data, as the measurement progresses, first, only the data of the part useful for determining the systolic blood pressure is stored in the memory,
Next, a digital sphygmomanometer characterized by comprising: window means for storing in the memory only data useful for determining diastolic blood pressure; and blood pressure determination means for determining blood pressure based on the data read from the memory. (2) The data extraction means starts extracting data of the pulse pressure oscillation signal by detecting a digital signal that shows a different change from a series of digital signal values that show a change with a substantially constant slope due to cuff decompression. A digital blood pressure monitor according to claim 1. (3) The data extraction means extracts data of the pulse pressure vibration signal corresponding to the peak of the amplitude signal obtained by subtracting a value corresponding to cuff decompression from the pulse pressure vibration signal. Or the digital blood pressure monitor described in paragraph 2. (4) The window means controls an amplitude smaller than the value determined according to the amplitude of the latest amplitude signal while the amplitude of the amplitude signal obtained by subtracting the value corresponding to cuff decompression from the pulse pressure oscillation signal shows an increase. 4. The digital sphygmomanometer according to claim 1, wherein data of past pulse pressure vibration signals is deleted from the memory. (5) The window means has a value determined according to the maximum amplitude of the past amplitude signal while the amplitude of the amplitude signal obtained by subtracting the value corresponding to cuff decompression from the pulse pressure oscillation signal shows a decrease after an increase. 5. The digital sphygmomanometer according to claim 1, wherein data of the latest pulse pressure vibration signal having an amplitude smaller than that of the digital sphygmomanometer is not stored in the memory.