JPH0441842Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to an abnormality detection device for a sensor for an automatic blood pressure measuring device.

Conventional technology Generally, a sensor such as a pressure sensor or a microphone is provided, and a cuff for compressing a part of a living body. Automatic blood pressure measuring devices are known that measure blood pressure based on blood pressure. In the sensor of such a device,
Abnormalities such as disconnection of the sensor, forgetting to connect it, or failure of the sensor body may occur.

Problems to be solved by this invention However, in such a device, there is no means for detecting the occurrence of an abnormality in the sensor as described above. Since the sensor is not detected at all, the device is operated without the person under test noticing that the sensor is abnormal, resulting in various inconveniences. For example, in an oscillometric automatic blood pressure measurement device that determines blood pressure based on cuff pressure oscillations that occur in synchronization with the pulse, if the pressure sensor is abnormal, the cuff pressure increase value is determined by the pressure sensor. Because it is not detected, a part of the living body is compressed more than necessary and blood pressure measurement is not started. In addition, in automatic blood pressure measurement devices using a microphone system, which uses a microphone to detect Korotkoff sounds generated in a part of the living body and determines blood pressure values based on the Korotkoff sounds, Korotkoff sounds occur when the microphone is in an abnormal state. The cuff stops lowering the blood pressure without being detected, and the correct blood pressure is not measured.

Means for Solving the Problems The inventor of the present invention has discovered that during the cuff pressurization period of such a device, a certain kind of noise is always included in the signal output from a normal sensor. I paid attention. That is, the present invention was developed against the background of the above-mentioned circumstances, and its gist is that it is equipped with a sensor such as a pressure sensor or a microphone, and a cuff for compressing a part of a living body, In an automatic blood pressure measuring device of the type that measures blood pressure based on the output signal of the sensor in the process of increasing the cuff pressure to a target cuff pressure and then gradually lowering the pressure, (b) maximum value determination means for determining the maximum value of the noise detected by the noise detection means; and (c) a means for determining the maximum value of the noise that is a predetermined constant value. and determining means for outputting an abnormal signal when the value falls below the value.

Effect of operation and invention By doing this, as shown in the claim correspondence diagram of FIG. 1, the maximum value of noise generated in the output signal from the sensor during the cuff pressure increase period detected by the noise detection means When the maximum value determined by the maximum value determining means falls below a predetermined constant value, the determining means determines that the sensor is not operating normally and outputs an abnormal signal, preventing the sensor from breaking. This provides the advantage that an abnormal state of the sensor caused by forgetting a tangent, or a failure of the sensor body, etc., is detected. The above-mentioned noise is caused by the pulsation of the pump, etc. that occurs when gas is supplied into the cuff from a pump, etc. during the cuff pressurization period, and the noise that occurs in the cuff in synchronization with the vibration of the gas supplied into the cuff. This occurs due to vibrations of the cloth or the like worn on the cuff, or rubbing of the cuff when gas is supplied to the cuff and the cuff is inflated.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail based on the drawings.

Fig. 2 shows an example in which the abnormality detection device of this embodiment is applied to an automatic blood pressure measuring device. 10 includes a pressure sensor 1
2. A rapid exhaust valve 14, a slow exhaust valve 16, and an electric pump 18 are connected to each other via piping 20. The pressure sensor 12 detects the pressure within the cuff 10 and supplies a pressure signal SP to the cuff pressure detection circuit 22 and the pulse wave detection circuit 24. The cuff pressure detection circuit 22 detects the cuff 10 from the pressure signal SP.
A cuff pressure signal SPc representing the static pressure (cuff pressure) Pc inside the cuff 10 is sent to the CPU 28 via the A/D converter 26.
supply to The pulse wave detection circuit 24 is equipped with a bandpass filter for discriminating the dynamic pressure within the cuff 10, that is, the pressure vibration component (pulse wave) that occurs in synchronization with the pulse, from the pressure signal SP, and actually measures the blood pressure value. During the pressure reduction process of the cuff 10, the pulse wave signal _SP0 representing the pressure vibration is sent to the CPU via the A/D converter 30.
Supply to 28. On the other hand, cuff 1 prior to blood pressure measurement
During the pressurization process of cuff 10, vibration components such as pulsations caused by the pump in the pressure signal SP are detected as noise generated during the pressurization process of the cuff 10, and a noise signal representing this is detected.
SN is supplied to the CPU 28 via the A/D converter 30. In this way, in this embodiment, the pulse wave detection circuit 2
4 also functions as a noise detection means.

The CPU 28 processes the input signal according to a program stored in the ROM 32 in advance while utilizing the storage function of the RAM 34, and outputs the input signal to the rapid exhaust valve 14, the slow exhaust valve 16, and the electric pump 18 via the output interface 36. At the same time, the blood pressure display 38 displays the blood pressure value. Further, the display 39 is for displaying an abnormality when an abnormal state of the pressure sensor 12 is detected.

Hereinafter, the blood pressure measurement operation will be explained according to the flowchart shown in FIG.

First, after various initial processes are executed in step S1, step S2 is executed to determine whether or not a start signal has been input. This starting signal is supplied from a starting switch 40 (shown in FIG. 2) operated at the time of starting, or periodically from a starting circuit (not shown) prepared for starting repeated blood pressure measurements. step
If the judgment in S2 is negative, the system is placed on standby, but if the judgment is positive, step S3 is executed, and the rapid exhaust valve 14 and slow exhaust valve 16 are closed, and the electric pump 18 is driven. Pressurization of the cuff 10 is started.

In the following step S4, the maximum value _Vpp(nax) of the noise signal SN detected by the pulse wave detection circuit 24 is determined within the boosting period of the cuff 10 in step S3, that is, within the period A shown in FIG. is determined. The noise signal SN is always generated in the pressure signal SP from the pressure sensor 12 during the pressurization period of the cuff 10 due to, for example, pulsation of the electric pump 18 or rubbing of the cuff 10 due to inflation. Therefore, step S4 corresponds to the maximum value determining means of this embodiment.

Next, in step S5, it is determined whether the cuff pressure P _c has reached a predetermined target cuff pressure P _n . This target cuff pressure P _n is set to a pressure that is sufficiently higher than the systolic blood pressure value of the subject, for example, about 180 mmHg. Steps S3 and subsequent steps are repeatedly executed until the cuff pressure P _c reaches the target cuff pressure P _n , but once the cuff pressure P c reaches the target cuff pressure P n , step S 6 is executed and the electric pump 18 is stopped. Then, in the following step S7, it is determined whether the maximum value Vpp _(nax) read in the step S4 is larger than a predetermined constant value K.

Here, the predetermined constant value K is set smaller than the maximum value V _{pp (nax)} in the normal pressure sensor 12 and larger than the maximum value V _{pp (nax)} in the pressure sensor 12 in an abnormal state. ing. Therefore, if it is determined that the maximum value V _{pp (nax)} is smaller than the certain value K, it is determined that the pressure sensor 12 is not operating normally, and the pressure sensor 12
An abnormal state is detected, and an abnormal signal is output to the display 39. That is, step S7 corresponds to the determination means of this embodiment. and,
In the following steps S8 and S9, an abnormality in the pressure sensor 12 is displayed on the display 39 in response to the abnormality signal outputted in step S7, and the rapid exhaust valve 14 is opened to indicate the broken line b in FIG. After the gas in the cuff 10 is exhausted as shown, the operations from step S2 onwards are executed again.

On the other hand, in step S7, the maximum value
If it is determined that V _pp(nax) is larger than a certain value K, it is determined that the pressure sensor 12 is operating normally, and steps S10 and subsequent steps are executed.
In step S10, the slow exhaust valve 16 is opened to start lowering the pressure of the cuff 10, and the subsequent step S11 is executed to determine whether the pulse wave signal SP ₀ has occurred in the process of lowering the pressure of the cuff 10. Step S12 is executed each time, and the peak value of the pulse wave is stored together with the actual cuff pressure value or the time of occurrence. And step
In S13, it is determined whether the actual cuff pressure P _c has become less than a predetermined constant value P _o . This value P _o is sufficiently lower than the diastolic blood pressure value of the subject, and is, for example, about 40 mmHg.
Initially, the cuff pressure P _c is greater than a certain value P _o , so
The determination in step S13 is negative, and the peak value of the pulse wave is stored during this time.

After that, if the judgment in step S13 is affirmed,
By executing the blood pressure value determination routine in step S14, for example, when the rate of change in the pulse wave magnitude reaches the maximum based on the change in the magnitude of the pulse wave peak value sequentially stored in step S12. The cuff pressure values are determined as the systolic blood pressure value and the diastolic blood pressure value, and the subsequent step S15 is executed and the determined blood pressure values are displayed on the blood pressure display 38.

As described above, in this embodiment, in step S4 corresponding to the maximum value determining means, the noise that is detected by the pulse wave detection circuit 24, which corresponds to the noise detection means, and which always occurs during the boosting period of the cuff 10 is detected. Maximum value V _pp(nax) of the represented noise signal SN
is determined, the maximum value V _pp(nax) determined in step S4 is determined in step S7, which is a determination means.
is below a certain value K, that is, the pressure sensor 12
If it is determined that there is an abnormality, an abnormality signal is output and the abnormality is displayed on the display 39, and the rapid exhaust valve 14 is opened to exhaust the gas in the cuff 10 and stop blood pressure measurement. Ru. Therefore, according to this embodiment, it is possible to eliminate the possibility that the blood pressure measurement operation is performed without noticing a wire breakage, a forgotten tangent, or an abnormality in the pressure sensor 12.

One embodiment of the present invention has been described above, but
The invention can also be applied in other aspects. In addition,
In the following description, parts common to those in the above-mentioned embodiments are given the same reference numerals, and the description thereof will be omitted.

In the embodiments described above, a case has been described in which the abnormality detection device is applied to an automatic blood pressure measuring device that measures blood pressure based on changes in the magnitude of pressure vibrations of the cuff 10 detected by the pressure sensor 12. , for example as shown in FIG.
are provided, and these microphones 50 and 5
The K sound and pulse sound are detected from the output signals SS ₁ and SS ₂ from the output signals SS 1 and SS 2 in the K sound detection circuit 52 and the pulse sound detection circuit 58, respectively, and a K sound signal representing these is detected.
The present invention is also applied to an automatic blood pressure measuring device that outputs the SK and pulse sound signals SW to the CPU 28 via the A/D converters 54 and 60. That is,
During the pressurization of the cuff 10 prior to blood pressure measurement, the K sound detection circuit 52 and the pulse sound detection circuit 58 detect signals from the microphones 50 and 56 attached to the distal and proximal sides of the cuff 10 during the pressurization process of the cuff 10. Signals SS ₁ and representing the noise generated
Among SS ₂ , signals having a frequency equivalent to the K sound or pulse sound are detected as noise, and noise signals SN ₁ and SN ₂ representing these are supplied to the CPU 28 via the A/D converter 30. And the noise signal
The maximum values of SN ₁ and SN ₂ are determined, and based on these maximum values, it is determined whether or not the microphones 50 and 56 are abnormal, as in the previous embodiment. In this embodiment, the K sound detection circuit 52 and the pulse sound detection circuit 58 constitute noise detection means, and the same effects as in the above-described embodiments can be enjoyed in this embodiment as well.

The above-mentioned embodiment is merely an embodiment of the present invention, and various changes may be made to the present invention without departing from the spirit thereof.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the claims of the present invention. Second
The figure is a block diagram showing the configuration of essential parts of an automatic blood pressure measuring device to which an embodiment of the present invention is applied. FIG. 3 is a flowchart illustrating the operation of the apparatus of FIG. 2. FIG. 4 is a time chart showing changes in the pressure of the cuff used in the device shown in FIG. FIG. 5 is a diagram corresponding to FIG. 2 of another embodiment of the present invention. 10...Cuff, 12...Pressure sensor, 24...
Pulse wave detection circuit (noise detection means), 50, 56...
... Microphone, 52 ... K sound detection circuit (noise detection means), 58 ... Pulse sound detection circuit (noise detection means), Step S4 ... Maximum value determination means, Step S7 ... Judgment means.

Claims (1)

[Claims for Utility Model Registration] The sensor comprises a sensor such as a pressure sensor or a microphone, and a cuff for compressing a part of a living body. An automatic blood pressure measuring device that measures blood pressure based on an output signal from the sensor, comprising: noise detection means for detecting noise generated in the output signal from the sensor during the pressure increase period of the cuff; An automatic blood pressure measurement characterized by comprising: maximum value determining means for determining the maximum value of noise that has been detected; and determining means for outputting an abnormal signal when the maximum value falls below a predetermined constant value. Abnormality detection device for equipment sensors.