JPH0144330B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic automatic sphygmomanometer that can automatically measure systolic and diastolic blood pressure values and display the measured values simply by starting the device.

In general, the standard clinical method for indirect blood pressure measurement is based on Korotkoff's auscultation method. That is, since the upper arm has an artery near the epidermis, a cuff band is wrapped around the upper arm and air pressure is applied into the cuff band at a rate of 20 to 30 mmHg/sec. When this cuff band is pressurized until the pressure value is 10 to 20 mmHg higher than the expected systolic blood pressure value, the artery is compressed and blood flow stops. Next, when the air pressure in the cuff band, that is, the cuff pressure, is gradually evacuated at a rate of 2 to 3 mmHg/sec, the artery is slightly opened, and during the cardiac systole, the arterial wave blood flow is increased at high speed to this small amount. As it begins to pass through the artery opened to
Due to arterial wave blood flowing laterally through the blood vessel wall, damped oscillations with a higher frequency than the arterial wave occur as so-called Korotkoff sounds, and the cuff band at this time becomes the systolic blood pressure level, and the cuff band gradually increases. As the pumping continues, Korotkoff sounds appear in synchronization with the arterial waves, and the location of the Korotkoff sounds also gradually moves from the systole to the systole in the arterial waves. When the sound occurs during cardiac diastole, the arteries have already opened and the blood flow is no longer constricted, so the Korotkoff sounds disappear. The systolic/diastolic blood pressure values are indirectly determined by using the cuff band at this time as the diastolic blood pressure value.

Conventionally, when automatically measuring blood pressure using an electronic blood pressure monitor based on the indirect blood pressure measurement method described above, the cuff strap, which is wrapped around the upper arm and has been sufficiently pressurized, is pressurized by locking the start switch. The Korotkoff sound is detected by a microphone attached to the cuff band while gradually exhausting air, and the cuff band at the time when a Korotkoff sound signal of a predetermined level or higher is output from the microphone is digitally displayed as the systolic blood pressure value. The cuff pressure at the time when the Korotkoff sound signal at a predetermined level is no longer output is digitally displayed as the diastolic blood pressure value. By the way, in order to accurately detect the onset and disappearance points of the Korotkoff sounds and to accurately measure the maximum or diastolic blood pressure values, the low-frequency component (3 to 50 Hz) of the Korotkoff sound signal that occurs during the systolic blood pressure is extracted using the first switch circuit. death,
The low-frequency component output from this first switch circuit is input to the systolic blood pressure measurement unit to detect the time point at which the Korotkoff sound occurs, and the cuff pressure at the time the Korotkoff sound appears is displayed as the systolic blood pressure value. The generated high-frequency component (80 to 120Hz) is extracted by a second filter circuit, and the high-frequency component output from this second filter circuit is input to the diastolic blood pressure measuring section to detect the point at which the Korotkoff sound disappears. , a method is adopted in which the cuff band at the time when the Korotkoff sound disappears is displayed as the diastolic blood pressure. However, when actually measuring the blood pressure of a large number of subjects using this method, the low-frequency component (the first
Since the relative onset and extinction points of the second filter circuit output) and the high frequency component (second filter circuit output) differ from person to person, there has been a problem that malfunctions occur. In other words, as a general pattern of a Korotkoff sound signal, a high frequency component as shown in FIG. 5b is obtained for a low frequency component of the Korotkoff sound signal as shown in FIG. It appears a little later and disappears a little earlier. However, some people may experience a signal pattern in which the high-frequency component disappears later than the low-frequency component, as shown in c in the figure, or a signal pattern in which the high-frequency component appears earlier than the low-frequency component, as shown in d in the figure. In the case of a signal pattern in which the high-frequency component appears much later than the low-frequency component, as shown in e of the same figure, and a signal pattern in which the high-frequency component appears earlier than the low-frequency component, as shown in d of the same figure, If the cuff pressure at the time when the low-frequency component appears is taken as the systolic blood pressure value, there is a problem in that the actual systolic blood pressure value is not accurately displayed. In addition, in the conventional example, by operating the diastolic blood pressure measurement unit at a time slightly delayed from the time when the low-frequency component appears (for example, at the time when four pulse outputs are output from the first filter circuit), the lowest At the start of the measurement operation of the blood pressure measuring section, the high frequency component of the Korotkoff sound is already output from the second filter circuit,
When the second filter circuit output is not obtained for a preset period of time (2 to 3 seconds), the cuff pressure at the time when the last output was obtained is displayed as the diastolic blood pressure value, so that the diastolic blood pressure value becomes normal. However, in the case of a signal pattern in which the high-frequency components appear much later than the low-frequency components, as shown in figure e, the Korotkoff sound may occur at the beginning of the measurement operation of the diastolic blood pressure measuring section. This means that the high-frequency component is not expressed, and if the onset of the high-frequency component is delayed for more than a certain period of time immediately after the start of the operation, there is a problem that the measurement operation ends without measuring the diastolic blood pressure value. . The present invention aims to solve the above problems.

Examples will be described below using figures. 1st
The figure and FIG. 2 show one embodiment of the present invention.
1 is a cuff band that is wrapped around the upper arm and closes blood vessels;
Reference numeral 2 denotes a main body block, and 2a a connecting portion between the cuff band 1 and the main body block, and the cuff pressure of the cuff band 1 can be freely adjusted by a pressure regulator 3 comprising a pressure pump 3a and electromagnetic valves 3b and 3c. Reference numeral 4 denotes a sound collection cuff with a built-in electret microphone 5, which is attached to the cuff band 1, and the microphone 5 detects Korotkoff sounds and pulse sounds. 7 is a Korotkoff sound detection circuit, which includes a first filter circuit 8 that extracts the low frequency component (30 to 50 Hz) of the Korotkoff sound signal from the output of the microphone 5 which is input via the pump noise removal filter 6; Ingredients (80~
120Hz), an OR circuit 10 that takes the logical sum of the outputs of both filter circuits 8 and 9, an output switching circuit 11 consisting of a flip-flop F, a transistor Q, and a relay Ry, and a pulse sound detection circuit. 12 and a noise removal circuit 15 consisting of AND circuits 13 and 14, and the output of the Korotkoff sound detection circuit 7 can be selected by switching a relay contact r. That is, an output switching circuit 11 is provided to switch the signal input to the operation control circuit 20 constituting both blood pressure measurement units to the OR output of the outputs of both filter circuits 8 and 9 or the output of the second filter circuit 9, and the output switching circuit 11
During the systolic blood pressure measurement operation, the OR output of both filter circuits 8 and 9 is input to the operation control circuit 20 and the systolic blood pressure measurement operation is performed. After the completion point, the output of the second filter circuit 9 is inputted to the operation control circuit 20, and the measuring operation of the diastolic blood pressure measuring section is started when the output of the second filter circuit 9 is obtained for the first time. I have to. 16 is a pressure detection display circuit, which includes a pressure detector 17 for detecting cuff pressure, an A/D converter 18 for converting an analog quantity outputted from the pressure detector 17 into a digital quantity, and an A/D converter 18 output. It is composed of a display 19 that provides digital display. Reference numeral 20 denotes an operation control circuit consisting of a microcomputer, which includes a pressure regulator 3, an output switching circuit 11 for the Korotkoff sound detection circuit 7, and a pressure detection display circuit 1.
6, the system automatically measures and digitally displays the systolic and diastolic blood pressure values just by the start operation, and detects the point in time when the output of the Korotkoff sound detection circuit 7 is first obtained. , a cuff pressure detection or display command is sent by the pressure detection and display circuit 16 to detect and display the systolic blood pressure value, and if the output of the Korotkoff sound detection circuit 7 is not obtained for a preset period of time (approximately 2 seconds), In this embodiment, the cuff pressure (stored in the memory of the operation control circuit 20) at the time when the last output was obtained is displayed on the display 19 as the diastolic blood pressure value. , the operation control circuit 20 and the pressure detection and display circuit 16 constitute a systolic blood pressure and diastolic blood pressure measuring section. On the other hand, the operation switching section that sets the operation timing of both measuring sections is a start switch (not shown),
It is formed by the timing setting section in the operation control circuit 20 and the output detection circuit 11 of the Korotkoff sound detection circuit 7, and starts the measurement operation by closing the start switch. The measurement operation of the diastolic blood pressure measuring section is started by the output of the Korotkoff sound detection circuit 7 which is input to the diastolic blood pressure measuring section. In this case, the output switching circuit 11 enters a standby state due to the systolic blood pressure measurement completion signal outputted when the measurement operation of the systolic blood pressure measuring section is completed, and when the output of the second filter circuit 9 is obtained for the first time, the output switching circuit 11 operates, and the output of the second filter circuit 9 is obtained as the output of the Korotkoff sound detection circuit 7, and is input to the operation control circuit 20.

The operation of the embodiment will be described in detail below. Now, when the starting switch (not shown) is turned on, the operation control circuit 20 outputs a drive signal for the pressurizing pump 3a and a closing signal for the solenoid valves 3b and 3c.
b, 3c are closed and the pressurizing pump 3a is driven to increase the cuff pressure. At this time, the cuff pressure is increased while the Korotkoff sound detection circuit 7 detects the Korotkoff sound signal, and the operation is controlled when the pressure is increased to the pressure (systolic blood pressure) + 20 mmHg at which the Korotkoff sound signal is no longer detected. A stop signal for the pressure pump 3a is output from the circuit 20, and the pressure pump 3a is stopped. By the way, during pressurization, the pump noise and Korotkoff sound generated from the pressurizing pump 3a are detected by the microphone 5, but a pump noise removal filter 6 is provided between the Korotkoff sound detection circuit 7 and the microphone 5. Therefore, only the Korotkoff sound signal is input to the Korotkoff sound detection circuit 7, and malfunctions due to pump noise can be prevented. In this case, the motor rotation speed of the pressurizing pump 3a should be set to 2400 rpm or less (pump noise is 400 Hz).
below) or above 6000 rpm (pump noise is 100
Hz or higher) to prevent pump noise from occurring within the distribution region (40 Hz to 100 Hz) of the signal component of the Korotkoff sound.

Next, at the same time as the pressurizing pump 3a stops, the operation control circuit 20 outputs a signal to gradually open the exhaust electromagnetic valve 3b, the electromagnetic valve 3b is opened, the cuff pressure is gradually reduced, and blood pressure measurement is started. At the start of measurement, the flip-flop F of the output switching circuit 11 of the Korotkoff sound detection circuit 7 is in a reset state by a command from the operation control circuit 20, and the relay contact r is switched to the systolic blood pressure measuring section a. Therefore, the logical sum (the fifth (shown in FIG. The noise removal circuit 15 is designed to detect Korotkoff sounds in synchronization with pulse sounds, and the pulse sound pulse P ₁ as shown in FIG. 3b outputted from the pulse sound detection circuit 12 and the filter circuit 8,
AND circuit 13 which receives as input the Korotkoff sound pulse P ₂ as shown in FIG. 3c output from 9;
At step 14, the AND of both pulses P ₁ and P ₂ is taken, and the third
The noise pulse P _N due to the noise signal N superimposed on the Korotkoff sound signal K shown in Fig. a is removed. During the cuff pressure reduction, the operation control circuit 20 stores in the memory the cuff pressure at the time when the Korotkoff sound first occurs, that is, at the time when an output is obtained from either of the filter circuits 8 and 9, and also reloads the cuff band 1. In order to pressurize, a pressurization signal is output and the pressurization pump 3a is restarted, and the cuff pressure is increased to 5.
Repressurize by ~10mmHg. Subsequently, the pressurized air in the cuff band 1 is gradually exhausted again, and the cuff pressure at the time when the Korotkoff sound appears is remeasured. If the remeasurement result is substantially the same as the measurement result stored in the memory, This cuff pressure is digitally displayed on the display as the systolic blood pressure value. On the other hand, if the re-measurement result is different from the measurement result stored in the memory, the re-measurement result is stored in the memory and the measurement is repeated until the measurement result substantially matches the measurement result stored in the memory. Let's do it. At this time, if the high-frequency component of the Korotkoff sound signal develops later than the low-frequency component as shown in Figure 5 b, c, and e, the cuff pressure at the time of the onset of the low-frequency component shown in Figure 5 a is at its maximum. If the high-frequency component appears earlier than the low-frequency component as shown in d of the same figure, the cuff pressure at the time the high-frequency component appears is displayed as the systolic blood pressure value, and the high-frequency component is displayed as the systolic blood pressure value. Systolic blood pressure values are measured. When the systolic blood pressure value is measured in this way, a systolic blood pressure measurement completion signal is output from the operation control circuit 20 and input to the flip-flop F, and the flip-flop F enters the standby state. is set to the high-frequency component output of the Korotkoff sound signal output from. When flip-flop F is set, transistor Q becomes conductive, relay Ry is driven, relay contact r is switched to the diastolic blood pressure measurement side b, and the output of the second filter circuit 9 is obtained as the output of the Korotkoff sound detection circuit 7. . When measuring the diastolic blood pressure value, the operation control circuit 2
0, the diastolic blood pressure measurement operation is started with the first output pulse output from the Korotkoff sound detection circuit 7, and the high-frequency component of the Korotkoff sound signal output from the second filter circuit 9 is obtained at the last time. The cuff pressure is displayed as the diastolic blood pressure value, and in the example, the cuff pressure at the time the Korotkoff sound occurs is sequentially stored in the memory, and if the next Korotkoff sound does not occur for 2 to 3 seconds. , repressurize the cuff pressure stored in the memory by 5 to 10 mmHg, and while gradually exhausting the pressurized air in the cuff band 1 again, re-inflate the cuff pressure at the time when the Korotkoff sound was last obtained. If the measurement is performed and a pressure substantially the same as the cuff pressure stored in the memory is obtained, this cuff pressure is digitally displayed as the diastolic blood pressure value. If the remeasurement result differs from the cuff pressure stored in the memory, the measurement will be repeated in the same manner as when measuring the systolic blood pressure. FIG. 4 is a diagram showing the above measurement operation.

When the maximum and diastolic blood pressure measurements are completed in this way, the rapid exhaust solenoid valve 3c opens according to a command from the operation control circuit 20 to rapidly reduce the cuff pressure, and when the cuff pressure reaches 0, the blood pressure measurement operation starts. finish.

The present invention is configured as described above, and includes a first filter circuit that extracts the low frequency component of the Korotkoff sound signal and a second filter circuit that extracts the high frequency component, and the output of either filter circuit. Since the cuff pressure at the time when is first obtained is displayed as the systolic blood pressure value, accuracy is maintained even when the onset of the high-frequency component of the Korotkoff sound signal is earlier than the onset of the low-frequency component. It has the effect that the systolic blood pressure value can be easily measured, and also has an output switching circuit that switches the signal input to the operation control circuit constituting both blood pressure measuring sections to the OR output of both filter circuit outputs or the second filter circuit output. The output switching circuit is switched and controlled by the systolic blood pressure measurement completion signal output from the systolic blood pressure measuring section, so that while the systolic blood pressure measuring section is operating, the OR output of the outputs of both filter circuits is input to the operation control circuit. After the completion of the systolic blood pressure measurement operation, the second filter circuit output is input to the operation control circuit, and when the second filter circuit output is obtained for the first time, the measurement operation of the diastolic blood pressure measurement section is started. As a result, there is no need for a switch operation to switch the measurement operation from systolic blood pressure measurement to diastolic blood pressure measurement, which simplifies the measurement operation. Furthermore, since the diastolic blood pressure measurement is started with the output of the second filter circuit that occurs after the completion of the systolic blood pressure, it is possible to Even if
This has the effect that the blood pressure measurement operation does not end without measuring the diastolic blood pressure, and the maximum and diastolic blood pressures can be automatically measured reliably. In other words, since the present invention automatically switches between the systolic and diastolic blood pressure operations, the measurement operation is simple and even an amateur can easily measure blood pressure. Since the system measures the systolic blood pressure based on the outputs of both filter circuits, and starts measuring the diastolic blood pressure based on the output of the second filter circuit after the completion of the systolic blood pressure measurement, the high frequency component of the Korotkoff sound Even if there are individual differences in the time point at which the low-frequency component appears, automatic switching of the measurement operations for the maximum and diastolic blood pressures can be performed accurately, and errors in measuring the maximum and diastolic blood pressures can be eliminated.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram of an embodiment of the present invention, FIG. 2 is a circuit diagram of the same, and FIGS. 3 to 5 are operation explanatory diagrams of the same. 1 is a cuff band, 5 is a microphone, 8 and 9 are filter circuits, 11 is an output switching circuit, 16 is a pressure detection and display circuit, and 20 is an operation control circuit.

Claims (1)

[Claims] 1 By operating the start switch, the pressurized air in the sufficiently pressurized cuff band wrapped around the upper arm is gradually exhausted, and the Korotkoff sound is detected by the microphone attached to this cuff band, and the sound is output from the microphone. The low-frequency components of the Korotkoff sound signal are extracted by the first filter circuit, and the high-frequency components are extracted by the second filter circuit.
a systolic blood pressure measurement section that detects the air pressure in the cuff band at the time when the output of any of the filter circuits is first obtained and displays it as a systolic blood pressure value, and finally a second filter A diastolic blood pressure measuring section that displays the air pressure in the cuff band at the time when the circuit output is obtained as a diastolic blood pressure value, and a diastolic blood pressure measuring section that inputs the filter circuit output to automatically measure the systolic and diastolic blood pressures, forming both blood pressure measuring sections. An output switching circuit is provided to switch the signal input to the operation control circuit to the OR output of both filter circuit outputs or the second filter circuit output, and the output switching circuit is connected to the systolic blood pressure measurement completion signal output from the systolic blood pressure measuring section. Therefore, by controlling the switching, the OR output of both filter circuits is input to the operation control circuit during the systolic blood pressure measurement operation, and after the completion of the systolic blood pressure measurement operation, the output of the second filter circuit is input to the operation control circuit. An electronic automatic blood pressure monitor characterized in that the measuring operation of the diastolic blood pressure measuring section is started when the second filter circuit output is obtained for the first time.