JPS6046976B2 - Breathing and cardiac motion measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a respiratory and cardiac motion measuring device for measuring the state of human respiratory motion and cardiac and knee motion.

BACKGROUND ART Human health conditions are measured by measuring the number of respirations and respiratory volume, that is, the ventilation volume, which indicates the exchange of air in the lungs, and by measuring the so-called pulseless heart rate. These are not only measured as a barometer to recommend health conditions, but also measure the breathing rate and new heart rate of a person who has undergone major surgery to determine whether the person is alive or in critical condition. Measurements are taken for two or three consecutive days to monitor the body's health, and in the same way, respiration and heart movement of premature infants are also measured throughout the day. By the way, conventional devices used to measure breathing and heart motion include a temperature sensing element, such as a thermistor, attached to the entrance of the nostril, and the electrical resistance of the temperature sensing element being measured by the air flow generated in response to breathing. The number of breaths can be detected by electrically detecting changes in the value, or by attaching a conductive rubber band to the chest and expanding and contracting the comb band due to the movement of the chest associated with breathing. One uses the change in resistance of a rubber band to measure it, and another measures it by attaching a device near the mouth that converts the flow of air into and out of the mouth into an electrical signal.
Also used were devices that attached electrodes to both sides of the lungs and measured the impedance between the electrodes.

Regarding the movement of the heart, the heart rate was measured using a so-called electrocardiogram. As described above, all conventional respiratory and cardiac motion measuring devices have a structure in which something is attached to the body and a lead wire is connected to the attachment.

For example, attaching such a device to a person who has undergone surgery is a nuisance for the person being measured, and leaving it attached for a few days may cause damage to the skin at the electrode part, for example. i. So-called rash may occur, and the attached detection elements and lead wires for them become a nuisance not only to the patient but also to those caring for them. Furthermore, even if such a device is attached to perform measurements, the attachment may affect the patient's mental health, and the measurement results may differ from those of breathing and pulse under normal conditions. In the present invention, fluctuations in the body weight of a human being in a sitting or standing position are detected, respiratory motion is measured from low frequency components of the fluctuations, and heart motion is detected from high frequency components. For example, if a person stands on a scale and measures this with good sensitivity, the center of gravity will move up and down with acceleration as the person breathes, and the center of gravity of the person will change due to the movement of the human heart. fluctuates up and down with acceleration, and this changes the weight. Weight fluctuations are detected as electrical signals by a load transducer that can sufficiently detect these fluctuations. By integrating the fluctuation component of the output of the load converter twice, the movement of the center of gravity in the height direction can be measured. Hereinafter, the respiration and cardiac motion measuring device according to the present invention will be explained with reference to the drawings.

For example, as shown in FIG. 1, the load in the vertical direction of the person to be measured is detected in the load detection circuit 1 as an electrical signal. This detection circuit 1 can use various types of pressure-sensitive elements such as strain gauges and piezoelectric elements that detect pressure as an electrical signal, for example, similar to those used in electrically configured weight scales. You can use the one. The output of the load detection circuit is integrated in a first integration circuit 2. The integrating circuit 2 includes, for example, an amplifier 4 having an integrating resistor 3 connected to its input terminal, and an integrating capacitor 5 connected to its input/output terminal. A switch 6 is connected to. In order to subtract the weight component of the subject from this load detection output, a variable resistor 8 is connected to both ends of the DC power supply 7, and the movable element of the variable resistor 8 is connected to the input terminal of the amplifier 4 through a resistor 9. be done. The movable element of the variable resistor 8 is adjusted to supply an electric signal corresponding to the gravity of the person to be measured to the amplifier 4, and the gravity component is subtracted from the detection output from the detection circuit 1, and the subtracted output is is integrated. The output of the first integrating circuit 2 is further integrated by the second integrating circuit 11. The second integrating circuit 11 also has the same function as the four integrating circuits 2.
It can be constructed from an amplifier 13 having an integrating resistor 12 connected to its input terminal, and an integrating capacitor 14 connected to its input and output terminals. Further, a reset switch 15 for setting the integral value to O in the initial state is connected in parallel with the capacitor 14. Switches 6 and 15 can be made dynamic. Furthermore, in order to remove the integral constant in the first integrating circuit 2, a variable resistor 19 is connected to both ends of the DC power supply 18, and its movable element is connected to the input terminal of the amplifier 13 through a resistor 20, and the variable resistor 19 is connected to the input terminal of the amplifier 13 through a resistor 20. An amplifier 4 is connected to one input terminal, and an amplifier 4 is connected to the other input terminal of this adder circuit 21.
The output end of is connected. The output of the second integrating circuit 11 is supplied to a dividing circuit 23 , where it is divided by the weight from the terminal 24 and reaches the output terminal 25 . This output terminal 25 is connected to a recorder, for example. In the above configuration, when the mass (weight) of the subject is W1, the vertical acceleration thereof is α, and the acceleration of gravity is g, the output e of the load detection circuit 1 is as follows.

This is because, when the distance in the vertical direction is Z, the acceleration α is a quadratic fluctuation component with respect to time in the vertical direction due to the fluctuation of the center of gravity.

Of these, the weight component Wg is subtracted by the output of the variable resistor 8. Therefore, the integral output of the integrating circuit 2 is as follows.

■o is an integral constant. This integral constant is determined by the variable resistor 19
is removed by the output of WdZ(t)/Dt at the input side of the second integrating circuit 12, and WdZ(t)/Dt is integrated in the second integrating circuit 12. Therefore, at the output terminal of the amplifier 13, WZ(t)
+4 is obtained. ZO is an integral constant. W is the weight (body weight), and the division circuit 23 divides the output of the second integrating circuit 11 by W, and also removes the integral constant 4 to calculate the vertical movement of the human body due to breathing and heart motion z(t) only can be obtained. To remove the weight component, for example, if you supply the output of the first integrating circuit 2 to an XY recorder from its output terminal and check the recording state, you will see that the weight component (constant value) Wg has been added. , the integral output of Wg increases linearly with time, and a component corresponding to the vertical fluctuation component is superimposed on this, and the integral constant V increases.

(constant value) are superimposed. That is, in this recording state, as shown by the curve 27 in FIG. 2A, the integral constant V is the superposition of the vertically varying component Wa/Dt on the linearly increasing component Wgt corresponding to the integral of a constant value of Wg. The result will be a shifted one. By adjusting the movable element of the variable resistor 8, as shown in FIG. 2B, if Wgt is made to be zero, that is, it does not monotonically increase linearly, the weight component has been removed. Further, the movable element of the variable resistor 19 is adjusted, and its output is added to the output of the integrating circuit 2 in the adding circuit 21, so that VO becomes zero, that is, the fluctuation component WdZ/ If Dt moves up and down around the zero level, the constant of integration becomes V. is removed. Therefore, the output of the variable resistor 19 is fed to the second integrating circuit 11 through the resistor 20, and the integral constant V is obtained from the output of the first integrating circuit 2. is removed and integrated in circuit 11. As mentioned above, the output of the second integration circuit 11 is WZ(t)+ZO, which is divided by W by the division circuit 23 and becomes Z(t).
)+4″ to the recorder.

The removal of integral constant 4 is the previous integral constant V. It is also possible to manually obtain the additional voltage by using a variable resistor (not shown) while monitoring the recording. Further, since the recording is simply performed with a shift, there is no need to remove the number 4, or it can be shifted by adjusting the zero point in the recorder. The recorded waveform of the output from the terminal 25 is, for example, as shown in FIG. 3A. That is, the pulse 32 of a higher frequency is superimposed on the low frequency component 31. In this waveform, the low frequency component 31 is a change in the center of gravity based on respiration, that is, a change in body weight that occurs with respiration. This was confirmed by the fact that this measurement was in good agreement with the measurement and recording of the subject's breathing simultaneously using a conventional respirator. Furthermore, the high frequency pulse 32 is a fluctuation in the center of gravity based on cardiac motion, and this can be understood from the fact that it also closely matches the electrocardiogram of the subject measured at the same time. Therefore, from the record shown in FIG. 3, it is possible to know the respiratory rate by counting the peak of the low frequency component 31, and it is also possible to measure the heart rate by counting the number of high frequency pulses in the same way.

Furthermore, in this low frequency component 31, this amplitude is the respiratory rate,
In other words, it corresponds to the ventilation volume of the lungs, and the ventilation volume can be measured by counting the amplitude scale of the recording. Similarly, the amplitude of the high frequency pulse 32 of the cardiac movement corresponds to the cardiac output, which can also be measured by reading the scale of its recorded amplitude. In order to measure these automatically, as shown in FIG. 4, the output of the terminal 25 is passed through a low-pass wave generator 33, and the output is shaped into a rectangular wave by a waveform shaping circuit 34.

Low pass? The wave generator 33 and the waveform shaping circuit 34 constitute a first wave shaping means, and the respiration rate is measured by counting the output thereof by a counting circuit 35 which is a first counting means.
Similarly, a high-frequency component 32 is extracted from the output of the terminal 25 by a high-pass filter 36, and a waveform shaping circuit 37 shapes the high frequency component 32 into a pulse. The high-pass p-wave generator 36 and the waveform shaping circuit 37 constitute a second Okinawa wave shaping means, and the output thereof is
The heart rate can be counted by counting with the counting circuit 38 which is a counting means. Furthermore, if the outputs of the Oki wavers 33 and 36 are recorded on recording paper, the result will be as shown in FIGS. 3B and 3C, in which a low frequency component representing respiratory motion and a pulse component representing heart motion are recorded, respectively. In this case, the cutoff frequencies of the Oki wavers 33 and 36 are each 2 hertz. In such measurements, Figure 5A
As shown in FIG.
The vertical movement of 3 can be recorded and measured as described above.

Alternatively, as shown in FIG. 5B, a chair 44 may be provided on the converting device 42, and the measurement may be performed with the person to be measured 41 sitting on the chair 44. In addition, in order to obtain the vertical movement of the center of gravity, in the above, the gravity component Wg was first subtracted from the output of the load conversion circuit 1 and then integrated, but the output of the load converter was first divided by the weight component W, and the The calculated force may be fixedly subtracted by the gravitational constant g, and the result may be integrated twice.゛As described above, the respiration and cardiac motion measuring device according to the present invention can measure respiration and cardiac motion without attaching anything to the subject, and is useful, for example, when conducting mass medical examinations. This is extremely convenient for measuring large numbers of people.

Furthermore, it is extremely convenient as it does not require operations to attach electrodes or other items, and allows quick and hassle-free measurements for both the person to be measured and the person performing the measurement operation. In the above description, both respiration and cardiac motion were measured, but if only one of them is required, it is of course possible to omit the measurement of the other.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an example of the respiratory and cardiac motion measuring device according to the present invention, Fig. 2 is a curve diagram for explaining the operation of Fig. 1, and Fig. 3 records the output of Fig. 1. Figure 4 is a diagram showing waveforms, Figure 4 is a circuit diagram showing an example of output processing, Figure 5 is a circuit diagram showing an example of output processing.
The figure is a diagram showing the number of measurements of the subject.

Claims (1)

[Claims] 1. A load detection circuit that detects the load of a human body placed on a load conversion device, a first integration circuit that integrates the detection signal of this load detection circuit, and an integration method that subtracts an integral constant from the output signal of this first integration circuit. a second integrating circuit, and a detection means for subtracting a body weight component due to gravitational acceleration in the calculation process by the first and second integrating circuits, and detecting a change in body weight based on the accelerated motion due to respiration and heart motion of the human body. , a first filtering and shaping means for extracting a low frequency component of the fluctuation detected by the detection means, and a first counting means for measuring the respiration rate of the human body by using the output signal of the first filtering and shaping means as a count. , a second filtering and shaping means for extracting a high frequency component of the fluctuation detected by the detection means, and a second filtering and shaping means for counting the output signal of the second filtering and shaping means to measure the cardiac motion of the human body.
1. A respiration and cardiac motion measuring device, characterized in that it has a counting means.