JPH0616752B2 - Blood pressure measurement device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a blood pressure measuring device for measuring blood pressure based on a vibration method utilizing a photoelectric volumetric pulse wave method, and makes a level of a photoelectric pulse wave signal within a predetermined range. This improves the accuracy of blood pressure measurement.

<Prior Art> As is well known, there is a blood pressure measurement device that uses the photoplethysmography method that enables blood pressure to be measured without restraint for a long time. Due to individual differences in the amount of transmission through passages (blood vessels, etc.), the photoplethysmographic signal level may be too large or too small, which may make it difficult to determine blood pressure.

<Object of the Invention> In view of the above circumstances, the present invention provides a blood pressure measurement device that adjusts transmitted light in advance for measurement sites having different light transmittances to keep the photoelectric pulse wave signal level within a certain range. The purpose of the present invention is to provide and reliably recognize the change of the photoelectric pulse wave signal.

<Example> Hereinafter, the present invention will be described with reference to the drawings.

The photoplethysmography is a pulse wave detection method that utilizes the property that the amount of transmitted light is inversely proportional to the amount of blood when light is applied to a peripheral part such as a fingertip, and is performed by a blood pressure measurement system as shown in FIG. To be done.

In the figure, reference numeral 1 denotes an elastic finger cuff made of rubber or a highly elastic vinyl chloride resin having a thickness of about 0.1 mm, and a light emitting element (light emitting diode) 2 and a light receiving element (phototransistor) 3 are attached to the finger cuff 1. Has been.

Further, the finger cuff 1 has a hole 4 formed therein.
A tube 5 for supplying pressure to the inside of the finger cuff 1.
Are connected. Further, the other end of the tube 5 is connected to a pneumatic circuit 6 for supplying pressure.

The light emitting element 2 and the light receiving element 3 are fixed to a blood pressure measurement point of a finger (for example, the ring finger of the left hand) 7 of the measurement subject such that the finger 7 is sandwiched.

In this case, the light emitting surface of the light emitting element 2 and the light receiving surface of the light receiving element 3 are set to face each other.

When pressure is supplied to the finger cuff 1, this pressure (hereinafter,
The cuff pressure) percutaneously presses the finger artery in the finger 7.

And in the process of increasing (or decreasing) the cuff pressure,
The light emitted from the light emitting element 2 passes through the blood vessel of the finger 7 and is received by the light receiving element 3. The change of the received light is converted into an electric signal, and the photoelectric pulse wave signal is detected.

The drive of the light emitting element 2 and the light receiving element 3 and the pressure fluctuation of the cuff pressure are controlled by the controller 8.

The cuff pressure is detected by the pressure sensor (piezoelectric converter) 9, and the detected pressure signal is input to the microcomputer 11 via the amplifier 10.

The photoelectric pulse wave signal is also input to the microcomputer 11 via the amplifier 12.

The microcomputer 11 performs waveform recognition processing from the obtained pressure signal and photoelectric pulse wave signal, calculates the systolic blood pressure and the diastolic blood pressure, and displays the systolic blood pressure and the diastolic blood pressure calculated on a display unit (not shown).

The microcomputer 11 is assumed to include a converter for A / D (analog-digital) converting the pressure signal and the photoelectric pulse wave signal.
1, the controller 8, the pressure sensor 9, and other electric circuits are all supplied with electric power from the power supply 13.

In the present embodiment, the light transmittance of the light emitted from the light emitting element 2, transmitted through the finger 7 and reaching the light receiving element 3 has individual differences depending on age, sex, etc., and thus the photoelectric pulse wave signal level is measured. In order to prevent a large change due to the difference between people, the predetermined cuff pressure is maintained for a certain time during the process of increasing the cuff pressure, and the level of the transmitted light amount is kept within the certain range so that the photoelectric pulse wave signal level is within the certain range within the time. Make adjustments.

Hereinafter, the blood pressure measurement operation including the adjustment of the transmitted light amount level will be described with reference to the pneumatic circuit shown in FIG. 2 and the pneumatic circuit control time chart shown in FIG.

In FIG. 2, reference numeral 1 denotes the finger cuff described above, and three electromagnetic valves 14, 15, 16 are connected to the finger cuff 1 via a branch pipe 17.

The first solenoid valve 14 is connected to a pressure adjusting valve 18 and a vacuum pump 19.

The second solenoid valve 15 is connected to the pressure regulating valve 20 and the pressurizing pump 21.

Furthermore, the third solenoid valve 16 is connected to the atmosphere opening hole 23 via a pressure reducing valve 22.

SW1 represents a first switch, SW2 represents a second switch, and SW3 represents a third switch. Each switch SW
1, SW2 and SW3 are the power source 13 and the driver 2, respectively.
4, between the power supply 13 and the AND gate 25, and the power supply 13
And the driver 26 are electrically connected and disconnected.

The second side of the AND gate 25 is connected to the input side of the second gate.
A comparator 27 is connected in addition to the switch SW2.

The comparator 27 includes a pressure sensor 9 and an amplifier 10.
The pressure signal obtained from the above is compared with the output signal of the constant voltage E _A or the output signal of the variable voltage E _B.

The constant voltage E _A is provided to maintain the cuff pressure at a constant pressure during the process of increasing the cuff pressure, while the variable voltage E _B is provided to determine the maximum value of the cuff pressure.

Then, whether the constant voltage E _A or the variable voltage E _B is connected to the comparator 27 is determined by the fourth switch SW4.

The AND gate 25 is opened depending on the state of the second switch SW2 and the output state of the comparator 27.

When the first switch SW1 is closed, the driver 24
Is activated, and decompression by the solenoid valve 14, the pressure regulating valve 18 and the vacuum pump 19 is started.

When the AND gate 25 is opened, the driver 28
Is operated, and pressurization by the solenoid valve 15, the pressure adjusting valve 20 and the pressurizing pump 21 is started.

Further, when the third switch SW3 is closed, the process of reducing the cuff pressure by the solenoid valve 16 and the pressure reducing valve 22 is started.

P of Figure 3 represents the cuff pressure of the finger cuff 1, above the pressure level 0 (shown by the arrow P _A) means positive pressure (indicated by arrow P _B) lower than the pressure level 0 negative pressure means.

Further, SW1, SW2 and SW3 in the figure respectively indicate the ON and OFF states of the first switch SW1, the ON and OFF states of the second switch SW2 and the third switch SW, respectively.
3 represents the ON and OFF states.

In SW4 pulse, and _{E A} side, and the fourth switch S
W4 means that the constant voltage E _A is connected to the comparator 27, and the E _B side means that the fourth switch SW4 connects the variable voltage E _B to the comparator 27.

ON / O of each switch SW1, SW2, SW3, SW4
The FF control is performed by the controller 8.

Blood pressure measurement is started at point A of the cuff pressure curve P in the same figure, and then blood pressure measurement is finished at point G.

The situation of each point is as follows.

Between A and B: The first switch SW1 is turned on, and the finger cuff pressure P becomes negative pressure.

Between B and C: The second switch SW2 is turned on, and the pressure is increased to a pressure determined by the constant voltage E _A.

Between C and D: Finger cuff pressure P is constant pressure (20 to 30 mm)
(Hg specific value).

Between D-E: second switch SW2 is turned ON, is pressurized to a pressure which is determined by the variable voltage _{E B.}

Between EF: The third switch SW3 is turned on, and the finger cuff pressure P gradually decreases according to the characteristics of the pressure reducing valve 22. Blood pressure measurements are taken during this depressurization process.

Between FG: The first switch SW1 is turned on, and the finger cuff pressure P becomes negative pressure.

Next, control for setting the photoelectric pulse wave signal level within a certain range between C and D will be described with reference to FIG.

In the figure, 2 represents the light emitting element, and 3 represents the light receiving element.

The light emitted from the light emitting element 2 passes through the blood passage of the measurement site and reaches the light receiving element 3. Therefore, the amount of transmitted light is evaluated by the current flowing through the light receiving element 3.

That is, when the amount of transmitted light is small and the current value flowing through the light receiving element 3 is less than the predetermined value, the operator lowers the resistance with the volume 29 to increase the light amount from the light emitting element, and the current value becomes the predetermined value. To adjust. On the contrary, when the amount of transmitted light is large and the current value flowing through the light receiving element 3 exceeds the predetermined value, the operator increases the resistance with the volume 29 to reduce the light amount from the light emitting element, and the current value is the predetermined value. Adjust so that

In this way, the reading of the ammeter 30 is confirmed while the cuff pressure is kept constant, and the current value is kept constant. That is, the amount of transmitted light is made constant.

By adjusting the amount of transmitted light in advance by the method described above, the photoelectric pulse wave signal level within a certain range can be obtained even for various fingers having different light transmittances.

The amount of transmitted light is photoelectrically converted by the light receiving element 3 and becomes a photoelectric pulse wave signal, which is transmitted to the amplifier 12.

<Effect> As described above, the blood pressure measurement device of the present invention includes a light-emitting element that emits light to the measurement site, and a light-receiving element that receives transmitted light emitted from the light-emitting element and transmitted through the measurement site. A conversion unit that converts a change in the amount of transmitted light received by the light receiving element into a photoelectric pulse wave signal, a constant pressure supply source that holds the cuff pressure at a constant pressure in the process of increasing the cuff pressure, and the constant pressure supply source. By adjusting the resistance value while the cuff pressure is kept constant, the voltage applied to the light emitting element is adjusted so that the photoelectric pulse wave signal level is within a certain range. Adjusting means for adjusting,
The cuff pressure is provided with a pressure supply source that supplies a pressure that determines the maximum value of the cuff pressure, and a measurement unit that measures blood pressure based on the photoelectric pulse wave signal in the process of decreasing the cuff pressure supplied from the pressure supply source. During the rising process, the predetermined cuff pressure is maintained for a certain period of time, and the level of the transmitted light amount is adjusted so that the photoelectric pulse wave signal level is within a certain range within the period, and then the maximum value of the cuff pressure is determined. Since the blood pressure is measured based on the photoplethysmograph signal in the process of decreasing the pressure, even at the measurement site where the light transmittance is different, the photoplethysmograph signal level can be set within a certain range by a simple adjustment. Therefore, it is possible to reliably recognize the change in the photoelectric pulse wave signal, and it is possible to accurately measure the blood pressure at any measurement site having individual differences.

[Brief description of drawings]

FIG. 1 is a block diagram of a blood pressure measuring device to which the present invention is applied, FIG. 2 is a pneumatic circuit diagram of the blood pressure measuring device, FIG. 3 is a time chart relating to pneumatic circuit control of the blood pressure measuring device, and FIG. It is a circuit diagram of a transmitted light amount adjustment unit of the blood pressure measurement device. 1 ... Finger cuff, 2 ... Light emitting element, 3 ... Light receiving element, 6 ...
… Pneumatic circuit, 7 ... Finger, 8 ... Controller, 9 ...
Pressure sensor, 11 ... Microcomputer, 29 ...
Volume, 30 ... Ammeter.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yasuhiko Murata 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Within Sharp Corporation (72) Inventor Hiroshi Makita 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Within the corporation

Claims (1)

[Claims] 1. A light-emitting element that emits light to a measurement site, a light-receiving element that receives transmitted light emitted from the light-emitting element and transmitted through the measurement site, and a change in the amount of transmitted light received by the light-receiving element. A converting means for converting into a photoelectric pulse wave signal, a constant pressure supply source for maintaining the cuff pressure at a constant pressure in the process of increasing the cuff pressure, and a constant pressure of the cuff pressure held at the constant pressure supply source. , Adjusting the voltage applied to the light-emitting element by adjusting the resistance value, adjusting means for adjusting the level of the transmitted light amount so that the photoelectric pulse wave signal level is within a certain range, and the maximum value of the cuff pressure. A blood pressure measurement, comprising: a pressure supply source that supplies a pressure that determines the pressure, and a measurement unit that performs blood pressure measurement based on a photoelectric pulse wave signal in the process of decreasing the cuff pressure supplied from the pressure supply source. Dress Place