JPH03121044A - Electronic hemadynamometer - Google Patents

Abstract

PURPOSE:To obtain an electronic hemadynamometer which correctly judges the smallness of the cuff vibration pulse wave and in which the measurement error due to the smallness of the cuff vibration pulse width is reduced, by suspending the measurement of the cuff vibration pulse width on the basis of the detection of the cuff vibration pulse wave up to the time when the max. blood pressure or the min. blood pressure through the Korotkoff method is recognized. CONSTITUTION:When a prescribed pressure is generated after pressurization, decompression is started. As decompression proceeds, recognition of the Korotkoff sound on the basis of a pulse wave gate and recognition of the Korotkoff sound on the basis of the time width are carried out in parallel until it is judged that the flag S1 or S2 is 1. If the decompression to 30mmHg or more from the start of decompression is generated at the time point when the flag S1 or S2 becomes 1, in other words, when the max. blood pressure is detected, the recognition of the Korotkoff sound due to the pulse wave gate is continued if three beats or more of the cuff vibration pulse waves are generated until the max. blood pressure is detected, and the contents of SYS1 and DIA1 are displayed as the max. blood pressure and the min. blood pressure, until the flag D1 becomes 1, in other words, until the max. blood pressure is recognized. When at most three beats of the cuff vibration pulse waves are not generated until the max. blood pressure is detected, the recognition of the Korotkoff sound due to the pulse wave gate is suspended, and the recognition of the Korotkoff sound due to the time width is carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electronic blood pressure monitor, particularly an electronic blood pressure monitor equipped with both the Korotkoff method and the oscillometric method.

[Prior art] The conventional measurement method using this type of electronic blood pressure monitor is to detect the cuff oscillation arterial wave synchronized with the Korotkoff sound in order to perform noise discrimination, open a gate, and then detect the blood pressure that enters the gate. There are methods that detect only the Korotkoff sound detection signal as Korotkoff sounds, and methods that measure blood pressure using both methods and then determine the optimal value based on the measurement results. However, if blood pressure is measured based on the cuff oscillation arterial wave when the cuff oscillation arterial wave is small, a large error will occur in the measurement result. For this reason, with oscillometric blood pressure monitors, if the pressure decreases by more than a certain value from the time the pressure begins to decrease until the first pulse wave is detected, it is determined that the pulse wave is small and the blood pressure measurement is stopped. was.

[Problems to be Solved by the Invention] However, in an electronic blood pressure monitor equipped with both the Korotkoff method and the oscillometric method, no solution has been taken for the case where the cuff vibration arterial wave is small. For this reason, in systems that perform noise discrimination of Korotkoff sounds using cuff oscillation artery waves, it is difficult to detect individual differences between living organisms, when the cuff is wrapped loosely, or when a slightly thick cuff is wrapped around a thin arm. If the cuff oscillation arterial wave is small, the systolic blood pressure will be measured to be lower than the actual one, and the diastolic blood pressure will be measured to be higher than the actual one. On the other hand, when the oscillometric method is performed using such a small cuff vibration arterial wave, a large error similarly occurs. Furthermore, under the conventional conditions for determining the cuff oscillation arterial wave, there is a problem in that when the pressurization is large, the cuff oscillation arterial wave is judged to be small even though it is not actually small.

The present invention eliminates the above-mentioned conventional drawbacks, and provides an electronic blood pressure monitor that accurately determines whether the cuff oscillation arterial wave is small and eliminates measurement errors due to the small cuff oscillation arterial wave.

Here, in a device that performs noise discrimination of Korotkoff sounds using cuff oscillation arterial waves, if the noise discrimination using cuff oscillation arterial waves is stopped when the cuff oscillation arterial waves are small, it becomes susceptible to the influence of noise. Also, if you set the time interval based on the period of the pulses detected so far, for example, if the average period T detected so far is 0.3 If there is a variation due to breathing (which may reach about +60%), Korotkoff sounds cannot be detected, resulting in an error in the measurement of the diastolic blood pressure. In other words, the pulsation period due to breathing (deep breathing, talking, etc.) may suddenly decrease to about 60%, and the pulsation period may become considerably large at the beginning and end of blood pressure measurement. . Furthermore, in the case of a single arrhythmia, which is relatively common, the rhythm is shifted due to the arrhythmia, making it impossible to utilize the previous periodicity.

Therefore, the present invention furthermore accurately determines whether the cuff oscillation arterial wave is small, eliminates measurement errors due to the small cuff oscillation arterial wave, and measures diastolic blood pressure due to minor single arrhythmia and respiratory fluctuations. To provide an electronic blood pressure monitor that eliminates errors.

[Means for Solving the Problem] In order to solve this problem, the electronic blood pressure monitor of the present invention measures blood pressure based on the generation or disappearance of Korotkoff sounds generated by compressing a part of a living body with a cuff. This electronic blood pressure monitor is equipped with both the Korotkoff method for measuring blood pressure and the oscillometric method for measuring blood pressure based on the change in magnitude depending on the time phase of the cuff oscillating arterial wave superimposed on the cuff pressure. The cuff oscillation arterial wave measurement stopping means is provided for stopping the measurement of the cuff oscillation arterial wave based on the detection of the cuff oscillation arterial wave up to the time when the systolic blood pressure or the diastolic blood pressure is recognized according to the method.

Here, the cuff oscillation arterial wave measurement stopping means is configured to stop the cuff oscillation arterial wave measurement when the cuff oscillation artery wave corresponding to the first detected Korotkoff sound is less than a predetermined number of beats since the first detection. Cancel measurement.

Further, the electronic blood pressure needle of the present invention includes a time zone setting means for setting a time zone for recognizing Korotkoff sounds based on the cuff oscillation arterial wave during cuff decompression, and a time zone setting means for setting a time zone for recognizing Korotkoff sounds, and a time zone setting means for setting a time zone for recognizing Korotkoff sounds based on the cuff vibration arterial wave during cuff decompression. blood pressure recognition means that recognizes a predetermined blood pressure based on the generation of Korotkoff sounds; and stopping the time period setting by the time period setting means based on the detection of the cuff vibration arterial wave up to the time of recognition of the systolic blood pressure. and means for canceling the time zone setting.

Here, the time period setting canceling means cancels the setting of the time period when the cuff vibration artery wave corresponding to the first detected Korotkoff sound is less than a predetermined number of beats since the first detection.

Furthermore, a second time slot setting means is provided for setting a time slot for recognizing the next Kotorokoff sound in a predetermined time width each time a Korotkoff sound is recognized, and the setting of the time slot is canceled by the time slot setting canceling means. In this case, another time slot is set by the second time slot setting means.

[Function] In this configuration, by using the cuff oscillation arterial wave as a gate for the Korotkoff sound, and by making a decision as to whether or not to perform the oscillometric method at the time when the systolic blood pressure is recognized,
It was accurately determined that the cuff vibration arterial wave was small, and measurement errors due to the small cuff vibration arterial wave were eliminated.

Furthermore, by providing a means for setting the time period for recognizing the next Kotorokoff sound of a predetermined time width each time a Korotkoff sound is recognized, it is possible to discriminate noise when detecting only Korotkoff sounds, and to detect mild single arrhythmias. and eliminates measurement errors in diastolic blood pressure due to respiratory fluctuations.

[Example] FIG. 1 is a block diagram showing the configuration of characteristic parts of an electronic blood pressure monitor of this example. Note that the cuff pressurization/depressurization control unit, power supply unit, etc. are not shown.

Also, FIG. 2 shows the output signals of each block.

10 is a Kotolokoff sound (K sound) measuring section, which includes a microphone 11 that collects blood flow sound, an amplifier 12 that amplifies the output voltage, a bandpass filter 13 that transmits a predetermined band corresponding to the Kotolokoff sound, and A/D conversion. 14, and outputs output data 83. Here, it is preferable that the amplifier 12 is one that amplifies a predetermined band. 20 is a cuff pressure/pulse wave measuring section, which includes a pressure sensor 21, an amplifier 22, and a
/D converter 23, and outputs output data 80.

3o is the output data 8 from the above-mentioned Kotlokoff sound measuring section 10.
3 to the threshold level 8 in the gate 81 created from the output data 80 from the cuff pressure/pulse wave measuring section 20.
It is a control unit that recognizes systolic blood pressure and diastolic blood pressure based on 2, and includes CPtJ31 for calculation and control, ROM 32 for storing control programs for CPtJ31, RAM 33 for auxiliary storage and input data storage, and input or output interface 34.35 It consists of. The CPt 131 has flags S+, Sz, and D+D2 (318 to 31d), and the RAM 33 has a 5YSI that stores the systolic blood pressure value based on the pulse wave gate and a DIA that stores the diastolic blood pressure value.

5Y82 that stores the systolic blood pressure value based on the time width from the previous Korotkoff sound and DI Ax that stores the diastolic blood pressure.
(33a-33d). Reference numeral 40 is a display device such as a liquid crystal display for displaying measurement results, and 50 is a key input unit for inputting instructions from an operator, which includes a power switch 52 and the like.

From the pressure signal 8o input from the pressure sensor 21 and converted into a digital value by the A/D converter 23, a gate 81 for Korotkoff sound recognition is created using a minimum point 80a and the next point 80b at the same level. In this gate 81, Korotkoff sounds are extracted by comparing the digital signal 83 input from the microphone 11 via the A/D converter 14 with a predetermined threshold level 82. Meanwhile, outside the gate 8
4 as well, noise is extracted by comparison with a predetermined threshold level 82. Here, the magnitude of the Korotkoff sound (peak and bottom) is determined from the digital signal from the Korotkoff sound detector.
is measured, and this magnitude is greater than a certain value, and the cuff vibration arterial wave superimposed on this is recognized from the digital signal from the pressure detection unit, and the gate is opened and the signal enters the gate. In this case, the presence of a Korotkoff sound signal is detected.

On the other hand, in the above method, for example, when two consecutive beats of Korotkoff sounds are detected, the cuff pressure value at the timing of the first detected Korotkoff sound is recognized as the systolic blood pressure. In parallel with this recognition of the systolic blood pressure, if the digital signal from the Korotkoff detection exceeds a certain threshold, and the interval between the signals detected, for example, 3 beats, is within 0.35 to 2 seconds. The Korotkoff sound recognition method is used in which the recognition condition for systolic blood pressure is that the

If systolic blood pressure is recognized under the former condition, if the cuff pressure value at the timing of systolic blood pressure is 30 m from the start of decompression.
The cuff oscillation arterial wave at the timing of the systolic blood pressure when the pressure is reduced by more than mHg is recognized for the first time, and then the cuff oscillation arterial wave is recognized.
If it is above the beat, data from the latter method is deleted to make effective use of the work area, and Korotkoff sound recognition is continued using the gate using the cuff vibration artery wave.
When no Korotkoff sounds are recognized for two consecutive beats, the cuff pressure value at the timing of the last recognized Korotkoff sound is taken as the diastolic blood pressure value.

However, if systolic blood pressure is recognized and the cuff pressure value at the timing of systolic blood pressure starts decompression, it becomes more than 30mmHg.
If the pressure has been reduced by more than 100%, and the cuff oscillation arterial wave at the timing of the systolic blood pressure is within 2 beats from when the cuff oscillation arterial wave was first recognized, the pulse wave is judged to be too small to be reliable. Korotkoff sound detection at the gate using the cuff oscillation arterial wave is discontinued, and detection using only the Korotkoff sounds described above continues, and for systolic blood pressure, a search is performed retroactively to the previously detected Korotkoff sounds, and two consecutive beats are detected. The cuff pressure value at the first timing is taken as the systolic blood pressure value. however,
The pressure value at this timing is 30mmH from the start of cuff decompression.
If g is not falling, do not measure the systolic blood pressure.
The cuff pressure value at the timing of the last beat is recognized as the diastolic blood pressure when the Korotkoff sound is not recognized for 4 seconds by continuing to recognize the Korotkoff sound. do.

Furthermore, even if the cuff pressure reaches 30 mmHg or less without any pulse wave being recognized, the blood pressure is naturally measured using the blood pressure recognition method using only Korotkoff sounds.

Here, the gate conditions when the pulse wave gate is not used are set as follows. When looking at the continuity of Korotkoff sounds using a blood pressure monitor for adults, the pulse rate (30 beats/min. 200 beats/minute) is usually considered based on the previously detected beat.
A gate with an interval of 0.35 seconds to 2 seconds from the previous Korotkoff sound is opened, and a Korotkoff sound is detected within this gate. Also, if the Korotkoff sound is not detected for 4 seconds, which is twice the 2 seconds equivalent to 30 beats/min than the last recognized Korotkoff sound, it is determined that it is Swan's fifth point (Korotkoff sound extinction point), The cuff pressure value at this time is recognized as the diastolic blood pressure value.

3A to 3C are flowcharts showing the operating procedure of the electronic blood pressure monitor of this embodiment.

First, after turning on the power, the blood pressure monitor is initialized in step S3.1, for example, flags S+, S2, D+, and D2 are set to "
0''. Pressurization is started in step S32, waits for the predetermined pressure to be reached in step S33, and then pressurized in step S32.
Start depressurizing at 34. As the pressure decreases, step S37
Korotkoff sound recognition based on the pulse wave gate and Korotkoff sound recognition based on the time width are performed in parallel in steps S35 to S36 until the flag S1 or S2 is determined to be "1". Step S35. The processing in S36 is shown in FIG. 3B,
This will be described later in accordance with FIG. 3C.

When the flag S+ or S2 becomes "1", that is, when the systolic blood pressure is found, the process proceeds from step S37 to step S38, where it is checked whether the pressure has been reduced by 30 mmHg or more since the start of the pressure reduction, and if the pressure has not been reduced, step 5YSI, SYS, "O" due to insufficient pressurization in S39
Set. If the pressure has been reduced by 30 mmHg or more, the process jumps to step S40, and then in step S40 it is checked whether there were three or more cuff oscillation arterial waves before the detection of the systolic blood pressure. If so, proceed to step S41, continue Korotkoff sound recognition using the pulse wave gate, wait until the flag DI becomes "1" in step S42, that is, the recognition of the diastolic blood pressure, and then set 5Y as the systolic blood pressure and diastolic blood pressure in step S43.
Displays the contents of SI and DIAI.

On the other hand, if there are no three beats of the cuff oscillation arterial wave by the time the systolic blood pressure is detected, the process proceeds from step S40 to step S44, where Korotkoff sound recognition using the pulse wave gate is stopped and Korotkoff sound recognition based on time width is performed. In step S45, the flag D2 becomes "l", that is, the diastolic blood pressure is recognized, and in step S46, 5 is set as the systolic blood pressure and diastolic blood pressure.
Display the contents of YS2 and DI A z.

Next, the routine of Korotkoff sound recognition using pulse wave gates in steps S35 and S41 will be explained with reference to FIG. 3B.

In step S51, it is checked whether the flag S+ or S2 is "1", that is, whether the systolic blood pressure has been recognized. If it has not yet become "1", it is checked in step S52 whether two consecutive beats of Korotkoff sounds have been recognized;
If it is recognized, the current cuff pressure is stored in step S53, and the flag S1 is set to "1" in step S54.
Set to and return. If it is not recognized, the process returns from step S52. On the other hand, either flag is
"1°°, the process advances to step S55 to check the condition that there is no continuous Korotkoff sound. If there is no Korotkoff sound, the process advances to step S56 to store the diastolic blood pressure value in DIAI and flag it in step S57. D1 is set to "1" and the process returns. If the above conditions are not satisfied, the process returns from step S55.

FIG. 3C shows step S36. This is a routine for recognizing Korotkoff sounds based on the time width of S44.

This routine performs Korotkoff sound recognition in a time period of 0.35 to 2 seconds from the previous Korotkoff sound recognition, stores the systolic blood pressure value in sys, the diastolic blood pressure value in DIA, and sets flags Sz and D2. do. Since the flowchart is similar to FIG. 3B, it will not be followed in detail here.

FIG. 4 is a diagram showing a display example of the electronic sphygmomanometer according to the present embodiment. In the case of recognition based only on Korotkoff sounds, a symbol ``■'' is displayed to distinguish it from the case recognized using a pulse wave gate.

In addition, by using the detected cuff oscillation arterial wave, the magnitude of the pulse wave is searched for on the systolic blood pressure side from the point of the maximum value of the detected cuff oscillation arterial wave, for example, and the magnitude is determined. The pressure value at the point where it first becomes less than 50% of the maximum value is the systolic blood pressure value using the oscillometric method.Conversely, the pressure value is searched for on the diastolic blood pressure side from the point of the maximum value, and the maximum value of the magnitude is calculated. The cuff pressure value at the point where it first becomes 70% or less may be set as the diastolic blood pressure value using the oscillometric method, and blood pressure recognition using the oscillometric method may also be performed. The reason for installing the oscillometric method in parallel is that when an arterial shunt is performed in a dialysis patient, blood flow noise occurs in this area, and this noise overlaps in frequency band with the Korotkoff sound. Korotkoff sounds are detected below the blood pressure, and the diastolic blood pressure cannot be recognized by the Korotkoff method and must be determined by the oscillometric method.Also, when there are individual differences, hypersensitivity, or an advanced state. Similarly, Korotkoff sounds may occur up to pressure values below the diastolic blood pressure, and there are cases in which the oscillometric method must be used to obtain the same.

Even in such a blood pressure monitor that uses both the Korotkoff method and the oscillometric method, if it is configured to stop measurement by the oscillometric method under the same conditions as described above and display only the measurement results by the Korotkoff method, this embodiment can be applied. A similar effect can be obtained.

As explained above, cuff oscillation arteries occur when the pulse is very weak or audible, or when the cuff is wrapped relatively loosely, or when a relatively large cuff is wrapped around a thin arm. When the waves are small, erroneous recognition of Korotkoff sounds can be avoided in the pulse wave gate using synchronization with the cuff oscillation artery wave used for noise discrimination in the Korotkoff method. In addition, misrecognition due to the oscillometric method can be avoided in a blood pressure monitor using the Korotkoff method, which is effective in the case of arterial shunt noise and an increased state of oscillometric method.

In addition, by installing another Korotkoff sound recognition method that measures only Korotkoff sounds before systolic blood pressure recognition, the above method can be easily realized, and it is also possible to easily and accurately determine whether the pulse wave is small. .

Furthermore, blood pressure can be easily and accurately measured using Korotkoff sounds alone, relatively unaffected by noise, without being affected by breathing or single arrhythmia.

[Effects of the Invention] According to the present invention, it is possible to provide an electronic blood pressure monitor that accurately determines whether the cuff oscillation arterial wave is small and eliminates measurement errors due to the small cuff oscillation arterial wave.

Furthermore, it is possible to accurately determine that the cuff vibration arterial wave is small, and eliminate measurement errors due to the small cuff vibration arterial wave,
It is possible to provide an electronic blood pressure monitor that eliminates measurement errors in diastolic blood pressure due to minor single arrhythmia and fluctuations due to breathing.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the configuration of the characteristic parts of the electronic blood pressure monitor of this embodiment, Fig. 2 is a diagram showing output signals from each block of the electronic blood pressure monitor of this embodiment, and Figs. 3A to 3C. 4 is a flowchart showing the operating procedure of the electronic blood pressure monitor of this embodiment, and FIG. 4 is a diagram showing an example of the display of the electronic blood pressure monitor of this embodiment. In the figure, 1o...Kotlokoff sound measurement unit, 11...Microphone, 12...Amplifier, 13...Band pass filter, 14...A/D converter, 20...Cuff pressure/pulse wave measuring section, 21... pressure sensor, 22... amplifier, 23... A/D converter, 30... Kotlokoff sound measuring section, 31... CPU, 31a... flag S4.
31b...Flag S2 31C...Flag D. 31d...Flag D232...ROM, 33...
RAM, 33 a'・SYS +, 33
b-S Y S 2.33 c = DI A,
r, 33d-DIA 2.34. 35...Interface, 40...Display device, 50.
...This is the key human resources department. Mi11) 1ζ cup 2nd figure 3B

Claims (5)

[Claims] (1) The Korotkoff method measures blood pressure based on the generation or disappearance of Korotkoff sounds generated by compressing a part of the living body with a cuff, and the time phase of the cuff oscillation arterial wave superimposed on the cuff pressure. An electronic sphygmomanometer equipped with both the oscillometric method for measuring blood pressure based on changes in size, and based on the detection of the cuff oscillation arterial wave up to the time of recognition of the systolic or diastolic blood pressure by the Korotkoff method. An electronic sphygmomanometer characterized by comprising: cuff oscillation arterial wave measurement stopping means for stopping measurement of the cuff oscillation arterial wave. (2) The cuff oscillation arterial wave measurement stopping means is configured to stop the cuff oscillation arterial wave measurement when the gullet oscillation artery wave corresponding to the first detected Korotkoff sound is less than a predetermined number of beats since the first detection. 2. The electronic blood pressure monitor according to claim 1, wherein measurement is stopped. (3) Time zone setting means for setting a time zone for recognizing Korotkoff sounds based on cuff vibration arterial waves during cuff decompression; blood pressure recognition means for recognizing a predetermined blood pressure based on the recognition of the systolic blood pressure; and time period setting canceling means for canceling the setting of the time period by the time period setting means based on the detection of the cuff vibration arterial wave up to the time of recognition of the systolic blood pressure. An electronic blood pressure monitor characterized by comprising: (4) The time zone setting canceling means cancels the time zone setting when the cuff vibration artery wave corresponding to the first detected Korotkoff sound is less than a predetermined number of beats after the first detection. The electronic blood pressure monitor according to claim 3, characterized in that: (5) A second time period setting means is further provided for setting a time period for recognizing the next Kotorokoff sound in a predetermined time width each time a Korotkoff sound is recognized, and the setting of the time period is canceled by the time period setting canceling means. 4. The electronic sphygmomanometer according to claim 3, wherein when the second time zone setting means sets a different time zone when the second time zone setting means is detected.