JPH01236068A - Pulsed magnetic field stimulated artificial respiratory device - Google Patents

Abstract

PURPOSE:To execute an artificial respiration close to a natural respiration by setting the repeating period of a pulse signal train impression to the period of the natural respiration and property setting the degree of the increment of the amplitude of a pulse train and a pulse interval. CONSTITUTION:When a thyristor 11a is reignited by a trigger pulse from a burst wave generating circuit 12, since the charging voltage of a capacitor 10 for storing a charge is made into a voltage higher than ever, also for the pulse to flow out to a multilayer solenoid 14, a peak value becomes high. In such a way, a pulse current making flow to the multilayer solenoid 14 is gradually increased, and it is stopped after it succeeds for about 1sec. The burst wave generating circuit 12 outputs a signal 1' for controlling the timing of the envelope of the pulse current, a signal 2' for controlling the timing of each pulse, and a trigger pulse signal 3' of the thyristor 11a having the same timing as the signal 2'. A sawtooth wave generating circuit 13b generates a sawtooth wave 4' from the signals 1' and 2'. The level of the sawtooth wave to be generated can be made variable by a volume 13b.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention provides a method for applying a fluctuating magnetic field generated when an intermittent continuous pulse current is passed through a coil to the phrenic nerve, etc. The present invention relates to a pulsed magnetic field stimulation ventilator that artificially performs breathing.

(Prior Art) Electrical stimulation of the phrenic nerve, which is currently performed for artificial respiration, is only an emergency measure and cannot be used for a long period of time because the electricity stimulates the skin and damages the skin. Surgery to attach electrodes directly to the long phrenic nerve is difficult and has not become common practice.

Most of the ventilators currently in use are devices that pump air in and out using positive pressure from the outside for ease of handling (Bird type, Emerson type, etc.).

These devices are simple in structure because they simply blow in air at a fixed pressure or volume, but physiologically, they put pressure on the alveoli and tend to cause injury, and the pulmonary artery pressure increases, which reduces the amount of blood circulating in the lungs. It is defective and cannot withstand long-term use. Additionally, procedures such as tracheotomy and tube intubation into the trachea are required.

For this purpose, Glenn's electrically stimulated diaphragm basing (Judson, J. P., & Glenn, W. W. L.
, :Radio-frequency electro
phrenic respiration:Long-
term application to a pat
ient with primary hypovent
ilation, J, A, M people, 20
3:1033-1037.1968). The current is R
It uses a method of wireless stimulation using F, allowing patients to leave the hospital and lead a normal life. Although this is an excellent device, it is difficult to perform surgery to properly expose the phrenic nerve and attach the electrodes, and only about 20 patients in Japan have undergone permanent implantation surgery.

On the other hand, many attempts have been made to stimulate nerves using induced currents caused by pulsed magnetic fields (for example,
la-tion of cardiac muscle
by a time varying mag-net
ic field, IEEE Trans Mag,
, MAG-6:321-322゜1970 ■Po1
son, M. J. R. et al.: Stimulat
ion ofnerve trunks with t
imevarying magnetic field
s.

Med, Biol, Eng, Compute, 2
0:243-244.1982 ■ Ryo Hoshi et al.: Nerve stimulation by pulsed magnetic fields, Medical Electronics and Bioengineering, 23 (
Proceedings of the 24th ME Society Conference): 248.1985
).

Magnetic stimulation has the advantage of being easy to reach deep areas and not damaging the skin surface.

Therefore, an attempt was made by a group at Tokyo Women's Medical University to stimulate the phrenic nerve, which is located somewhat deep, using an induced current generated by a pulsed magnetic field. (Akio Nagano et al., Basic study of respirators using transcutaneous phrenic nerve magnetic stimulation, Medical Electronics and Bioengineering, 24 (Proceedings of the 25th ME Society Conference)
: 539.1986).

The device used is the same as the conventional one, which uses a thyristor to instantaneously discharge electricity stored in a capacitor into a coil, emitting a single pulse.

(Invention or problem to be solved) However, unlike the cardiac PA (involuntary muscle), the respiratory muscle (voluntary muscle) is different from the cardiac PA (involuntary muscle), and if the action potential of the motor nerve is stimulated once with a single pulse, the muscle will become a single wire (spastic muscle). It only causes short-term contractions like this, but does not result in functional, rational, comprehensive movement.

The single line of the diaphragm becomes so-called ``blow-up,'' and the ventilation volume per breath does not reach 400 m1.

If you do it continuously, it can hardly be called artificial respiration, and your diaphragm will quickly become fatigued. Continuous contraction of the diaphragm for about 1 second still requires continuous stimulation of pulses as in diaphragm basing. The pulse is a train pulse whose amplitude gradually increases during inspiration.

SUMMARY OF THE INVENTION In view of the problems of the conventional devices described above, an object of the present invention is to provide a pulsed magnetic field stimulation ventilator that can apply train pulse-like stimulation to the diaphragm in synchronization with the breathing cycle with the intensity gradually increasing during the inhalation time. That is.

(Means for Solving the Problems) The present invention has the following means configuration to achieve the above object.

That is, the pulsed magnetic field stimulation ventilator of the present invention includes: a sawtooth wave voltage generation power source that intermittently generates a sawtooth wave voltage having a constant initial value at a cycle close to the human breathing cycle; and: a magnetic field generation coil. and; a switching means for intermittent application of the sawtooth wave voltage to the magnetic field generating coil; and a switching control means for causing the switching means to intermittent the application of the sawtooth wave voltage at a period shorter than the time width within the time width of the sawtooth wave. It is characterized by comprising the following.

(for production) Hereinafter, the present invention having the above-mentioned means will be explained in detail.

The sawtooth wave voltage generation power supply generates a sawtooth wave voltage whose amplitude increases over time from a constant initial value corresponding to the stimulation threshold at a cycle close to the human breathing cycle. This sawtooth wave voltage is applied to the magnetic field generating coil via switching means. The switching means is turned on and off by the switching control means within the time width of the sawtooth wave at a period shorter than the time width and at an appropriate period determined experimentally or theoretically. Therefore, a pulse train voltage is applied to the magnetic field generating coil such that the envelope of the peak value is the same as the waveform of the T degree sawtooth voltage. And it will repeat itself in the breathing cycle.

When such a pulse train-like voltage is applied to the magnetic field generating coil, a corresponding magnetic field is generated.

When this magnetic field generating coil is placed near the clavicle so that the magnetic field reaches the phrenic nerve, eddy currents due to changes in the magnetic field flow near the phrenic nerve, and this eddy current stimulates the phrenic nerve, causing the diaphragm to is contracted.

Now, the current flowing through the magnetic field generating coil is ■. (t).

If the magnetic flux density near the phrenic nerve produced by the same coil is B(t), the relationship between the two is B(t) cG I c(t)
(1) becomes.

Eddy current I, (t
) is I e(t ) cc −! ! -Lll--(2)dt.

From formula (1) and formula (2>) I　e(t　　)cC”　’----(3) dt The eddy current ■8 is dI. (t)/dt.

This vortex lacquerwork. stimulates the phrenic nerve, causing the diaphragm to contract. Therefore, as dIc/dt increases, the contraction of the diaphragm becomes stronger. On the other hand, if the inductance of the magnetic field generating coil is the inductance, and the voltage across the coil is VC, then at the beginning of the discharge of the capacitor 2, the voltage is L.

dt stop door a-ocv. --1(4)' dt, and from equations (3) and (4), 1, sink V. ---(5) and eddy current ■8 is the voltage ■ applied to the magnetic field generating coil. It can be seen that it is proportional to .

By the way, as mentioned above, the voltage applied to the magnetic field generating coil is a pulse train voltage whose peak value envelope gradually increases like a sawtooth wave during inspiration, so an eddy current occurs. As the pulse train gradually increases, the stimulation of the phrenic nerve, that is, the depth of breathing, gradually increases. Inhalation occurs in a state close to natural, and when the pulse train ends, exhalation occurs, and exhalation ends. From there, the same action is repeated again to obtain a respiration curve that is close to natural.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram of an embodiment of the present invention.

This magnetic stimulation respirator consists of a rectifier diode 1 connected to a 100cm commercial power source, a smoothing capacitor 2, and a PWM
(Pulse Width Modulation
: pulse width modulation) phototerlington transistor 3 for modulation, high frequency power transformer 4, high frequency rectifier diode 5, smoothing capacitor 6, high frequency choke 7, differential amplifier 8b for voltage feedback with attenuator 8a, PWM Modulation circuit 9 and charge storage capacitor 1
0 and the multilayer solenoid 1 which is the load with the charge accumulated in this
Thyristor lla and pulse transformer llb for instantaneous flow to thyristor lla, burst wave generation circuit 12 for firing thyristor lla and supplying a synchronization signal to sawtooth wave generation circuit 13a, and generating a sawtooth wave from the synchronization signal. a sawtooth wave generation circuit 13a and a volume 13b for generating
and a multilayer solenoid 14 for converting the pulsed current stored in the charge storage capacitor 10 and flowing through the thyristor lla into a pulsed magnetic field.

Among the above components, the multilayer solenoid 14 is a magnetic field generating coil referred to in the means configuration, and the thyristor 11a and pulse transformer Ilb constitute a switching means, and are part of a burst wave generation circuit that sends a signal to the pulse transformer Ilb. 1 section serves as a switching control means, and the others constitute a sawtooth wave voltage generating power source.

The magnetic field generating coil used in this embodiment was a 2×3 rectangular copper wire wound 60 times in 12 rows and 5 layers, and had a self-inductance of about 50 μH.

Note that the numbers ■, ■, ■, etc. in FIG. 1 correspond to the numbers in the waveform timing diagram shown in FIG.

The operation of this embodiment will be explained below. When the power is turned on, the commercial voltage of 100V is rectified by the rectifier tie-out 1, and a voltage of about 140V is generated in the smoothing capacitor 2. This is converted to several tens of kilohertz by photodarlington transistor 3.
z high frequency PWM modulation. When this is applied to the high frequency power transformer 4, a high frequency voltage approximately proportional to the PWM modulation degree on the primary side is generated on the secondary side thereof, so this is rectified by the high frequency rectifier quarto 5 and smoothed by the smoothing capacitor 6. Immediately after the power is turned on, the terminal voltage of the smoothing capacitor 6 is low, and the output of the differential amplifier 8b is a high voltage. The output duty cycle of the PWM modulation circuit 9 increases as the input voltage increases, and at this time the smoothing capacitor 6 is rapidly charged. As the charging voltage increases, the output voltage of the differential amplifier 8b decreases, the duty cycle of the output of the PWM modulation circuit 9 decreases, the charging current to the smoothing capacitor 6 decreases, and eventually the two input voltages of the differential amplifier 8b decrease. Charging is performed until the voltage is equal to the voltage. Now, assuming that the voltage between the terminals of the smoothing capacitor 6 is Vl, the voltage division ratio of the attenuator is p, and the output of the sawtooth wave generating circuit 13a is Vs, the following equation holds true in this state.

V, -V, /ρ ~---(6) Since the output ■3 of the sawtooth wave generating circuit 13a is a voltage like a sawtooth wave as shown in FIG. 2 ■, the voltage between the terminals of the smoothing capacitor 6 ■1
is the same sawtooth wave voltage ■ which is multiplied by 1/ρ.

(1) Charges the charge storage capacitor 10 through the high frequency choke 7.

This charging is completed in several tens of meters (Fig. 2).

After charging is completed, thyristor lla or burst wave generation circuit 12
The electric charge stored in the charge storage capacitor 10 flows at once to the multilayer solenoid 14 (Fig. 2).

At this time, the electric charge charged in the smoothing capacitor 6 by the high frequency choke 7 does not flow out much.

The current flowing through the multilayer solenoid 14
Since the resonant circuit formed by the charge storage capacitor 10 attempts to reverse after several hundred microseconds, the thyristor lla becomes open and the current flowing through the multilayer solenoid 14 stops.

A high frequency choke 7 is connected to the charge storage capacitor 10.
The charging current flows in again through.

When the thyristor lla is fired again by the tri-force pulse from the burst wave generating circuit 12 (Fig. 2 ■), the charging voltage of the charge storage capacitor 10 is higher than before, so the multilayer solenoid 14 is The outgoing pulse also has a high peak value. In this way, the pulse current flowing through the multilayer solenoid 14 gradually increases and stops after continuing for about 1 second (Fig. 2).

Now, the burst wave generation circuit 12 generates a signal ■ to control the timing of the envelope of the pulse current, a signal ■ to control the timing of each pulse, and a tri-force pulse of the thyristor lla having the same timing as the signal ■. Outputs signal ■.

The sawtooth wave generating circuit 13a generates a signal (2) and a sawtooth wave (2). The level of the generated sawtooth wave can be varied by the volume 13b.

As a result of the above, breathing similar to natural breathing as shown in (■) in FIG. 2 is performed.

(Effects of the Invention) As explained above, in the pulsed magnetic field stimulation ventilator of the present invention, the pulse peak value corresponds to the stimulation threshold at a time corresponding to the inspiratory time in the magnetic field generating coil that stimulates the phrenic nerve. By applying a pulse train voltage that gradually increases from the initial value and generating an eddy current proportional to the pulse voltage near the phrenic nerve, stimulating the phrenic nerve and strengthening diaphragm contraction in accordance with the gradual increase in the eddy current. The patient inhales, and at the end of the pulse train signal, contraction is released, exhalation is performed, and the pulse voltage is applied again to start inhalation, so the repetition period of pulse signal train application is set to the natural breathing period. There is an advantage that artificial respiration that is close to natural respiration can be performed by appropriately setting the degree of gradual increase in the amplitude of the pulse train and the pulse interval based on experimental data and the like. Another advantage is that breathing can be started immediately by simply applying a magnetic field generating coil to the vicinity of the collarbone, allowing other treatments to be carried out while waiting for natural breathing to begin. Furthermore, as is clear from the above, there is no need for surgery to attach electrodes to the phrenic nerve as with conventional electrical stimulation methods, nor is there a need for tracheotomy or tube intubation, and air is pumped in and out using positive pressure from the outside. It has the extremely remarkable advantage that breathing can be performed with pulmonary artery blood flowing naturally without damaging the alveoli as would be the case when breathing.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an embodiment of the pulsed magnetic field stimulation ventilator of the present invention, and FIG. 2 is a waveform timing diagram of each part in the embodiment of FIG. 1. Rectifying diode, 2... Smoothing capacitor, 3-- Phototerlington transistor for PWM modulation, 4... High frequency power transformer, 5.
High frequency rectifier diode, 6...smoothing capacitor,
7...High frequency choke, 8a...Attenuator, 8b...-Differential amplifier for voltage feed hack, 9...PWM modulation circuit, 10.Charge storage capacitor, lla...Sirisk, llb
...Pulse transformer, 12. Burst wave generation circuit,
13a ・Sawtooth wave generation circuit, 13b ・
Volume, 14...Multilayer solenoid. Agent Patent attorney Yoshi Yahata Hiroshi Hiroshi's various parts of the remains 4 Misogyu 2 Do

Claims (1)

[Claims] a sawtooth wave voltage generation power supply that intermittently generates a sawtooth wave voltage having a constant initial value at a cycle close to a human breathing cycle;
a coil for generating a magnetic field; a switching means for intermittent application of the sawtooth wave voltage to the coil for generating a magnetic field; and a switching means for intermittent application of the sawtooth wave voltage at a cycle shorter than the time width within the time width of the sawtooth wave. A pulsed magnetic field stimulation ventilator, comprising: switching control means for controlling the pulsed magnetic field.