JPS5810096B2 - Sphygmomanometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sphygmomanometer that applies pressure to a cuff band wrapped around the upper arm of a human body and measures systolic and diastolic blood pressure based on the presence or absence of Korotkoff sounds when the cuff band is decompressed. It is something.

Generally, in blood pressure monitors that utilize Korotkoff sounds, the blood pressure at the time when the first Korotkoff sounds occur during cuff decompression is determined to be the systolic blood pressure. There was a possibility that this could be incorrectly determined to be a Korotkoff sound, resulting in an incorrect measurement of systolic blood pressure.

Therefore, as disclosed in Japanese Patent Publication No. 55-34583, when Korotkoff sounds are not detected periodically even after waiting a certain period of time after the first Korotkoff sound is detected, it is determined that the layer pressure is not the highest. A new blood pressure monitor has been proposed.

However, since such conventional methods determine that those that occur periodically are true Korotkoff sounds, in the case of a person with an arrhythmia in which a part of the pulse is missing when measuring systolic blood pressure, the first sound is actually the Korotkoff sound. There is a problem in that even though it is necessary to determine that the sound is a true Korotkoff sound, it is determined that it is not a true Korotkoff sound because it does not occur periodically.

By the way, it is known that arrhythmia occurs during the measurement of systolic blood pressure in most cases between the first and second Korotkoff sounds. The purpose of this invention is to provide a blood pressure monitor that can reliably measure systolic blood pressure even in people with arrhythmia.

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows the system configuration of an embodiment of the present invention, in which a cuff band 1 that is wrapped around the upper arm of a human body is equipped with a pressurizing pump 2 that supplies pressurized air to the cuff band 1. and cuff band 1
a slow exhaust valve 3 that gradually exhausts the pressurized air inside the cuff band 1;
A sound detector 5 such as a microphone that detects sound pressure fluctuations in the cuff band 1 is also connected to the cuff band 1.
attached to.

Further, the control discrimination circuit 8 is a circuit part that controls the entire system, including the K sound interval measurement circuit 9 and the pressurization time measurement circuit 12.
, a repressurization time setting section 14, a pressure discrimination circuit 15, a systolic/diastolic blood pressure value display section 16, and others, and are constituted by a microcomputer.

First, the operation of normal blood pressure measurement will be explained.

When the measurement push button 17 is turned on with the cuff 1 wrapped around the upper arm of the human body, the control discrimination circuit 8 starts the pressurizing pump 2, and the cuff pressure detected by the pressure conversion circuit 4 increases to 11.
0-120mmH? When the control determination circuit 8 determines via the pressure determination circuit 15 that the pressure has reached 1, the drive of the pressurizing pump 2 is temporarily interrupted.

During this pressurization interruption period, the control discrimination circuit 8 receives the output of the sound discrimination circuit 6 via the sound interval measurement circuit 9, and when the Korotkoff sound recognition signal is received, the control discrimination circuit 8 detects that the cuff pressure is insufficient. The repressurization time setting unit 14 determines that
The pressurizing pump 2 is operated for 0.5 to 3 seconds set by .

Here, the sound discrimination circuit 6 inputs the output of the sound detector 5 attached to the cuff band 1 and processes the human input signal using a band pass filter that passes only the frequency band components of the Korotkoff sound. Signal processing is performed using a pulse sound synchronous discrimination method that utilizes the fact that Korotkoff sounds occur in synchronization with pulse sounds (arterial waves), and a Korotkoff sound recognition signal corresponding to the actual occurrence of Korotkoff sounds is output.

After the pressurization pump 2 has been operated for the time set by the re-compression time setting unit 14, when the pressurization of the cuff band 1 by the pressurization pump 2 is interrupted again, the Korotkoff sound recognition signal is input again. When the control discrimination circuit 8 receives the Korotkoff sound recognition signal, the re-inflation time setting section 14 is activated again, and the cuff band 1 is re-inflated.

After repeating the pressurization of the cuff band 1, the interruption of the pressurization, and the reception determination of the Korotkoff sound recognition signal at that time as described above, the cuff band 1 reaches a sufficient cuff pressure value. When the brachial artery around which the arm is wrapped is completely occluded, the blood flow is completely cut off, and the Korotkoff sound is no longer generated, and therefore the Korotkoff sound recognition from the sound discrimination circuit 6 No signal is output.

Therefore, after the repressurization time set by the repressurization time setting unit 14 has elapsed and the operation of the pressurizing pump 2 has been interrupted, if a predetermined time elapses without receiving the Korotkoff sound recognition signal, the control determination circuit 8 detects completion of pressurization of the cuff band 1, and opens the slow exhaust valve 3 to gradually exhaust the pressurized air in the cuff band 1. At the same time, the measurement in progress display indicating that the blood pressure measurement is in progress is displayed on the measurement in progress display section 18. It will be held in

In the process of slowly exhausting pressurized air from the cuff band 1,
When the first Korotkoff sound occurs and is input to the control discrimination circuit 8 as a Korotkoff sound recognition signal, the control discrimination circuit 8 discriminates the cuff pressure value of the pressure conversion circuit 4 output at this time as the systolic blood pressure value, This is stored in the systolic/diastolic blood pressure value storage circuit 16 and digitally displayed on the systolic blood pressure value display section 7a of the display section 7.

On the other hand, every time the Korotkoff sound recognition signal is received, the control discrimination circuit 8 updates and stores the cuff pressure value at that time as a tentative diastolic blood pressure value in the systolic/diastolic blood pressure value storage circuit 16, and displays this on the display section 7. This is displayed on the diastolic blood pressure value display section 7b.

If the Korotkoff sound recognition signals that have been manually input one after another are not input for a predetermined period of time, the control discrimination circuit 8 detects that the generation of the Korotkoff sounds has ended, and the cuff control circuit 8 detects that the Korotkoff sound recognition signals have been generated. The pressure value is stored as a determined diastolic blood pressure value in the systolic/diastolic blood pressure value storage circuit 16 and displayed on the diastolic blood pressure value display section 7b.

Thereafter, the rapid exhaust valve 13 is opened by the output of the control discrimination circuit 8 to rapidly exhaust the pressurized air within the cuff band 1, thereby completing all blood pressure measurement steps.

Next, the operation in an abnormal state according to the present invention will be explained.

Here, the sound interval measuring circuit 9 connected to the output of the sound discrimination circuit 6 detects the Korotkoff sound from the first Korotkoff sound recognition signal to the fourth Korotkoff sound recognition signal during the slow exhaust stroke from the cuff band 1 during blood pressure measurement. The period until the sound recognition signal is assumed to be the period in which the recognition abnormality detection mode is in effect, and during this period, the generation interval of each Korotkoff sound recognition signal is measured. Operate.

Here, the period from the first to the fourth Korotkoff sound recognition signal is defined as the period of recognition abnormality detection mode. This is because it is considered that the pressure will not be reduced from the systolic blood pressure value to the diastolic blood pressure value, and in this example, the period up to the fourth shot was set as the recognition abnormality detection mode period.
The number of shots to be taken as the mode period is determined in relation to the speed of gradual decompression of the cuff band during blood pressure measurement.

However, in the process of pressurizing cuff band 1, the Korotkoff sound is always detected at each interruption in pressurization, so that the pressurization state with repeated pressurization and interruptions continues, and the first pressurization pump 2 If the pressurization state continues even after a predetermined period of time has elapsed since the start, the pressurization time measuring circuit 12 is activated and determines that the cuff band 1 is not properly wrapped. The abnormality determination circuit 10 is activated by the output of the time measurement circuit 12.

If the pressure discrimination circuit 15 determines that the cuff pressure has still increased abnormally and has reached about 300 mmHg, the output of the pressure discrimination circuit 15 activates the overrise prevention circuit 19, and the output of the overrise prevention circuit 19 activates the overrise prevention circuit 19. The exhaust valve 13 is opened to rapidly exhaust the pressurized air within the cuff band 1, and the abnormality determination circuit 10 is also activated.

On the other hand, in the process of slow exhaustion from cuff band 1, the second Korotkoff sound recognition signal does not occur even after approximately 4 seconds have elapsed after the first full-time Korotkoff sound recognition signal is generated. When the interval measuring circuit 9 makes a determination, the abnormality determining circuit 10 is activated by the output of the interval measuring circuit 9.

In other words, even if a person's heart rate is around 40 and one-beat intermittent pulse occurs, it is thought that the second Korotkoff sound will occur within 4 seconds after the first Korotkoff sound. If the Korotkoff sound recognition signal of the second utterance is not input even after 4 seconds or more have elapsed since the Korotkoff sound recognition signal of the eye, it is determined that noise has been input. Abnormality determination circuit 1 based on output
0 will be activated.

The above-mentioned interval indicates that the interval between the occurrence of the Korotkoff sound recognition pulse between the second utterance and the third utterance, or the interval between the occurrence of the Korotkoff sound recognition pulse between the third utterance and the fourth utterance, has become 2.5 seconds or more. When detected by the measurement circuit 9, the next Korotkoff sound is thought to occur even in a person with a heart rate of 40 if the heartbeat interval is about 1.5 seconds.In the above case, it is also considered that noise was input. Therefore, the abnormality determination circuit 10 is activated by the output of the interval measurement circuit 9.

In this way, when up to the fourth Korotkoff sound recognition signal is detected and the recognition abnormality detection mode ends, the mode is automatically switched to the above-mentioned diastolic blood pressure detection mode. When the next Korotkoff sound is not recognized within a predetermined time (2.5 seconds) after the sound recognition signal is detected, the cuff pressure value at the timing of the development of the detected Korotkoff sound recognition signal is determined as the diastolic blood pressure value. .

When the abnormality determination circuit 10 is activated in this way, the display state shown in FIG. 2A during normal operation is changed as shown in FIG.
The abnormal state of measurement failure is displayed on the abnormality display section 11, and all displays on the display section 7 and the measuring display section 18 are turned off, so that the occurrence of the abnormal state can be accurately notified.

In the block diagram of FIG. 1, each circuit such as the control discrimination circuit 8, the intertone measurement circuit 9, the abnormality discrimination circuit 10, the pressurization time measurement circuit 12, etc. is actually realized as a program operation of a microcomputer. Therefore, the operation of the interval measurement circuit 9 is used not only when detecting an abnormality as described above, but also when measuring the diastolic blood pressure.

In the figure, 20 is a power light.

The present invention is constructed as described above, and is a sphygmomanometer that applies pressure to the cuff band, determines systolic blood pressure and diastolic blood pressure based on the presence or absence of Korotkoff sounds during decompression, and displays them. A blood pressure monitor that uses an interval measurement circuit to measure the Korotkoff sound interval two to several times in succession from the first Korotkoff sound, and displays an abnormality when the next Korotkoff sound is not input within the respective set time for each measurement port. In this case, the time set for the first measurement port is set longer than the time set for the second and subsequent measurement ports, so when measuring systolic blood pressure, the Korotkoff sound should occur after the first Korotkoff sound due to arrhythmia. Even if the Korotkoff sound is missing, the first Korotkoff sound will not be determined to be noise simply because it is not a periodic sound, as in the conventional example, and the first sound is a true Korotkoff sound. It has the advantage of being able to accurately determine the presence or absence of a Korotkoff sound, and since the measurement interval for the second and subsequent Korotkoff sounds is short, there is no risk that the noise component will be mistaken for a true Korotkoff sound. There is an advantage.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 a+b is an explanatory diagram of the above during normal operation and when an abnormality occurs. 1 is a cuff band, 2 is a pressurizing pump, 3 is a slow exhaust valve, 4 is a pressure conversion circuit, 5 is a sound detector, 6 is a sound discrimination circuit, 7 is a display section, 8 is a control discrimination circuit, 9 is an interval measurement circuit, 10 is an abnormality discrimination circuit, and 11 is an abnormality display Section I2 is a pressurization time measuring circuit.

Claims (1)

[Scope of Claims] 1. A blood pressure monitor that applies pressure to the cuff band and determines and displays systolic blood pressure and diastolic blood pressure based on the presence or absence of Korotkoff sounds during decompression, which For blood pressure monitors that measure the Korotkoff sound interval two or several times in succession from the Korotkoff sound, and display an abnormality when the next Korotkoff sound is not input within the respective set time for each measurement port, the first measurement A blood pressure monitor characterized in that the set time for the mouth is longer than the set time for the second and subsequent measurement ports. 2 The setting time for the first measurement port is approximately 4 seconds, and 2
The blood pressure monitor according to claim 1, characterized in that the setting time for the measurement port after the first measurement is approximately 2.5 seconds.