JPH0463688B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic blood pressure monitor that measures systolic blood pressure and diastolic blood pressure by detecting Korotkoff sounds.

In general, an electronic blood pressure monitor consists of a cuff that covers a rubber bag into which air can be freely injected, a Korotkoff sound detection means, a pressure detection means within the rubber bag, and a system that processes the signals output by these means. and means for determining and displaying the hypertension value and the diastolic blood pressure value. To use this, first wrap the cuff around your arm,
Air is forced into the rubber bag so that the pressure in the bag is slightly higher than the human body's standard systolic blood pressure, thereby ischemizing the artery, and then the air is removed to gradually lower the pressure inside the rubber bag. In this case, when the pressure inside the rubber bag reaches a certain value, Korotkoff sounds are generated from the artery.
The measured value of the pressure inside the rubber bag at this time is the systolic blood pressure value. As the air is further removed, the Korotkoff sound disappears. The measured value of the pressure inside the rubber bag at this time is the diastolic blood pressure value. In this way, the highest and lowest blood pressure values are measured.

By the way, this type of conventional electronic blood pressure monitor is equipped with a microphone in its arm cuff as the Korotkoff sound detection means. However, since the area of the sound receiving surface of this microphone is small, it is difficult to correctly place the sound receiving surface above the artery that is the source of the Korotkoff sound, and blood pressure may not be measured accurately. Further, depending on the position where the cuff is worn, the Korotkoff sound may not be detected, and in that case, it is necessary to put on the cuff again and measure the blood pressure, resulting in the inconvenience that the blood pressure measurement cannot be carried out efficiently.

Further, as described above, conventional electronic blood pressure monitors use a microphone as the Korotkoff sound detection means, and a semiconductor strain gauge or diaphragm as the pressure detection means. However, these detectors are expensive and large in size, which is a major hindrance to providing an inexpensive and convenient blood pressure monitor.

The present invention has been made in view of the actual state of the prior art as described above, and its purpose is to be able to measure blood pressure without depending on the wearing position of the arm cuff. That is, the object of the present invention is to provide an electronic blood pressure monitor that can detect Korotkoff sounds over a wide range, is inexpensive, and has a simple structure.

To achieve this objective, the present invention is characterized in that two conductive flexible sheets are stacked in the arm cuff, and Korotkoff sounds and pressure are detected by changes in their contact resistance. There is.

Embodiments of the electronic blood pressure monitor of the present invention will be described below based on the drawings. FIG. 1 is a plan view showing the configuration of a cuff of an electronic blood pressure monitor according to an embodiment of the present invention, in which numeral 1 indicates a cuff made of cloth or the like, numeral 2 is provided within the cuff 1, and
Rubber bag for pressurizing the artery by filling air, 3
Reference numeral 4 indicates a rubber tube which is an air supply/exhaust passage for the rubber bag 2, 4 is a conductive rubber sheet for detecting Korotkoff sound or pressure, and 5 is a lead wire connected to the conductive rubber sheet.

FIG. 2 is a cross-sectional view showing the arm cuff 1 shown in FIG. 1 wrapped around the arm 6 of the person to be measured. The same reference numerals as in FIG. ). FIG. 3 is a detailed view of part A in FIG. 2, in which two conductive rubber sheets 4 are stacked as shown, and 7 is a contact surface between the two conductive rubber sheets 4.

4 and 5 are circuit block diagrams of an electronic blood pressure monitor according to an embodiment of the present invention, respectively. FIG. 4 is a circuit block diagram when both Korotkoff sound and pressure are detected using a rubber sheet 4. FIG.

In Fig. 4, 8 is the blood pressure monitor body, 9 is the amplifier, 10 is an arrow indicating the pressure inside the rubber bag 2, 11 is the pressure detector, and 12 is an abstraction of the contact resistance over the entire surface of the two conductive rubber sheets 4. The reference numeral 13, which is shown as a plurality of resistors, is a pressure regulator that takes in and out the air inside the rubber bag 2. Next, the operation will be explained based on this figure. First, air is pressurized into the rubber bag 2 using the pressure regulator 13, and the pressure is set to a value slightly higher than the standard systolic blood pressure value of the human body, thereby isolating the artery. When the pressure inside the rubber bag 2 is gradually lowered from this state using a pressure regulator, Korotkoff sounds are generated from the artery at a certain pressure value. This Korotkov sound is equipped with 2 inside the cuff 1.
Vibration is applied to the contact surface 7 of the conductive rubber sheet 4, and the generation of Korotkoff sound is detected as a change in the contact resistance 12 of the contact surface 7 due to the vibration. However, due to a change in the pressure 10 inside the rubber bag 2, the contact force on the contact surface 7 also changes, and this change also increases the contact resistance 1.
Detected as a change in 2. These detection signals have the waveform shown in FIG. 6a and are sent to the amplifier 9 (the fourth
(Figure). As this waveform shows, the output value of the Korotkoff sound is affected by the contact resistance of the conductive rubber sheet 4 serving as the detection section, that is, by the pressure inside the rubber bag 2. However, the pressure detector 11 (Fig. 4)
Since the amplification degree of the amplifier 9 is controlled by the output of the amplifier 9, the output of the amplifier 9 is corrected as shown in the waveform shown in FIG. 6b, and can be processed in subsequent circuits (display circuits, etc.). In this way, the generation of Korotkoff sound is caused by the contact resistance 1 of the contact surface 7 of the conductive rubber sheet 4.
2, and the rubber bag 2 at that time
The pressure value within is detected by the pressure detector 11 and the systolic blood pressure value is displayed. Then, when the air in the rubber bag 2 is further removed by the pressure regulator 13, the disappearance of the Korotkoff sound is detected as a change in the contact resistance 12 of the conductive rubber sheet 4, as in the case of the occurrence. The value of the pressure inside the rubber bag 2 at that time, that is, the diastolic blood pressure value is detected and displayed by the pressure detector 11, and the blood pressure measurement is completed.

Next, a different embodiment from the above embodiment, ie, a case where both Korotkoff sound and pressure are detected using the conductive rubber sheet 4, will be described with reference to FIG. 5, which is a circuit block diagram for that case. In this figure, 14 is a Korotkoff sound selection filter, 15
is a pressure detection circuit. In the electronic blood pressure monitor of this embodiment as shown in the figure, the generation and disappearance of Korotkoff sounds is caused by the change in contact resistance 12 of the contact surface 7 (FIG. 3) of the two conductive rubber sheets 4, as in the previous embodiment. Detected as . Also, the pressure inside the rubber bag 2 is 10
Since the contact force on the contact surface 7 is changed due to the change in the contact resistance 12, the pressure inside the rubber bag 2 is also detected as a change in the contact resistance 12. That is, these signals
The waveform shown in Figure a is input to the amplifier 9 and the pressure detection circuit 15. The signal input to the amplifier 9 is input to the Korotkoff sound selection filter 14, whose output waveform becomes the waveform shown in FIG. 6b, and the Korotkoff sound is detected. On the other hand, the pressure at the time of Korotkoff sound generation and extinction is detected by the signal input to the pressure detection circuit, and the maximum and minimum blood pressure values are displayed via the subsequent circuits.

As detailed above, according to the present invention, the conductive flexible sheet for detecting Korotkoff sounds covers a wide range of the circumference of the arm of the person to be measured. Korotkoff sounds can be detected no matter where the artery, which is the source of the sound, is located, and therefore accurate blood pressure measurement can be efficiently performed regardless of the position where the cuff is worn. In addition, since the detection of Korotkoff sound and pressure is performed by changing the contact resistance of two conductive flexible sheets with a simple structure, it is possible to This eliminates the need for a semiconductor strain gauge or the like for detection, and has the effect of providing an inexpensive and easy-to-use electronic blood pressure monitor.

[Brief explanation of drawings]

FIG. 1 is a plan view showing the configuration of the cuff of an electronic blood pressure monitor according to an embodiment of the present invention, FIG. 2 is a sectional view showing the cuff of FIG. 1 wrapped around the arm, and FIG. 2, 4 and 5 are circuit block diagrams of an embodiment of the present invention, and FIG. 6a shows the output signal of the conductive rubber sheet (the input signal of the amplifier or pressure detection circuit). ), FIG. 6b is the output signal of the amplifier with respect to FIG. 4, and the output signal of the Korotkoff sound selection filter with respect to FIG. 1... Bracelet, 2... Rubber bag, 4... Conductive rubber sheet, 7... Contact surface, 9... Amplifier, 10... Arrow indicating pressure, 11... Pressure detector, 12... Abstractly expressed contact resistance, 14...Korotkoff sound selection filter,
15...Pressure detection circuit.

Claims (1)

[Claims] 1. A cuff provided to cover a rubber bag into which air can be press-fitted, a Korotkoff sound detection means, a pressure detection means within the rubber bag, and a signal outputted by the two means is processed to determine the systolic blood pressure value and An electronic sphygmomanometer comprising means for determining and displaying a diastolic blood pressure value, wherein two conductive flexible sheets are stacked in the arm cuff as means for detecting at least one of the Korotkoff sound and pressure. An electronic blood pressure monitor characterized by: