JPS6127065B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for controlling the discharge amount of an infusion pump so as to maintain the pump discharge pressure constant regardless of fluctuations on the load side.

Today, in the medical field, various infusion pumps are used for drug administration, extracorporeal circulation, animal perfusion experiments for various research purposes, and the like. However, most of these types of pumps have a constant flow rate, so in order to bring the infusion pattern closer to the hemodynamics of the living body, pulsatile infusions are used especially for extracorporeal circulation in cardiac surgery and perfusion of medicinal solutions in organ preservation. There is a growing demand for pumps with patterns. Further, in an infusion pump, the discharge pressure or perfusion pressure is influenced by the load on the pump, that is, the state of the side receiving the infusion when the pump discharge amount is kept constant. That is, when an infusion pump is used for research on perfusion of living organs or peripheral hemodynamics, if the perfusion time is extended over a long period of time, the pressure increases as the resistance of the blood vessels increases, making tissue destruction more likely to occur. Therefore, in order to prevent such pressure increase, it is desirable to automatically control the pressure to a constant pressure.

Therefore, in an infusion pump, the inventor
As a result of intensive research to create a device that can adjust the discharge amount so that the discharge pressure or perfusion pressure of the pump can be maintained constant regardless of fluctuations in the load side, we have found that If a digital signal for pump drive control is generated to control the average value to a constant value, and then the generated digital signal is used to adjust the pump discharge amount so as to control the pump discharge pressure, We have found that the discharge control of infusion pumps can be easily achieved.

That is, the discharge pressure or perfusion pressure is averaged by an integrator, the obtained average value is compared with a predetermined set pressure value by a comparator, and if the measured pressure is lower than the set pressure, the oscillator is activated based on the output of the comparator. to operate the addition/subtraction counter in addition mode and modify the pump operation so that the discharge pressure increases, and if the measured pressure is higher than the set pressure, activate the oscillator based on the output of the comparator to operate the addition/subtraction counter in addition mode. is configured to operate in a subtractive mode and modify the pump operation so that the discharge pressure decreases.

In this case, as a pump drive control method for adjusting the pump discharge amount by controlling the discharge pressure using the digital signal of the addition/subtraction counter, the present applicant has already published Japanese Patent Application Laid-Open No. 54-36089 and Japanese Patent Application Laid-Open No. Those proposed in Japanese Patent No. 54-125891 are preferably used. In this case, as a method of adjusting the pump discharge amount, a method of adjusting the flow rate, and a method of adjusting the pulsation rate when the infusion pattern is pulsatile can be adopted. Therefore, if the flow rate is adjusted by providing a frequency converter that converts the digital signal of the addition/subtraction counter into a pulse train with a frequency proportional to the magnitude of the digital signal, the frequency is changed to the maximum infusion volume setting oscillator of the drive control circuit already proposed. Pump drive control can be smoothly achieved by replacing the frequency converter with a period setting oscillator when adjusting the pulsation rate.

The purpose of the present invention is to prevent tissue destruction that is likely to occur due to increased pressure due to increased resistance in blood vessels when perfusion is performed for a long period of time, such as during extracorporeal circulation or perfusion of medicinal solutions for organ preservation. To provide a discharge pressure control device for an infusion pump configured to adjust the pump discharge amount with precision and to always maintain the pump discharge pressure constant without being affected by instantaneous pressure fluctuations on the load side.

In order to achieve the above object, the present invention includes means for measuring and averaging the pump discharge pressure, means for comparing the averaged measured pressure with a predetermined set pressure, and a means for comparing the averaged measured pressure with a predetermined set pressure. a counter that generates a constant signal when the measured pressure is within the range of , and generates a signal that increases or decreases by performing addition mode or subtraction mode operation when the measured pressure is lower or higher than the set pressure; The pump is characterized by comprising a control circuit that adjusts the pump discharge amount according to the output of the counter.

In the above-mentioned discharge pressure control device, it is preferable that the means for measuring the pump discharge pressure and averaging the same be constituted by an integrator.

The means for comparing the measured pressure and the set pressure consists of a pair of comparators connected in parallel, each setting an upper limit pressure and a lower limit pressure, and generates a clock pulse when the measured pressure wanders outside the set pressure range. It is preferable to energize an oscillator to perform the addition/subtraction of the counter using this clock pulse.

The counter consists of an addition/subtraction counter, and can be selectively set to addition mode, subtraction mode, or operation stop state by the output of the comparator, and any initial base value can be set by a preset signal. In addition mode or subtraction mode, the output of the clock pulse oscillator When addition or subtraction is performed, the corresponding digital signals are output, and when the calculation is stopped, a predetermined setting signal is output.

The control circuit that adjusts the pump discharge amount includes a frequency converter that converts the output signal of the counter into a pulse train with a frequency proportional to the magnitude of the output signal, and a circuit that controls the drive pulse motor using the pulse train as a control signal. It is preferable to configure the following.

For example, the pulse motor drive control circuit includes an oscillator that sets acceleration, constant speed, and deceleration times, respectively, and a status counter that instructs the operation of each oscillator and instructs an addition or subtraction operation to an addition/subtraction counter.
An oscillator that sets the cycle of the rotation mode, an addition/subtraction counter that adds or subtracts the signal from the oscillator according to the commands of the status counter, a frequency converter that converts the contents of the addition/subtraction counter into a pulse signal with a frequency proportional to it, and a frequency converter for each device. It can be composed of a monostable multivibrator that generates an actuation timing pulse, an oscillator that sets the maximum infusion volume, and a pulse motor drive circuit.

Next, embodiments of a discharge pressure control device for an infusion pump according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the basic configuration of the present invention, in which an integrator 10, comparators 12 and 14,
It is composed of an addition/subtraction counter 16, a NAND gate 18, and an oscillator 20 for generating clock pulses. That is, the integrator 10 introduces a measured pressure consisting of the discharge pressure or the perfusion pressure, averages it, and sends the output of the integrator 10 to the comparators 12 and 14 connected in parallel. These comparators 12,
At 14, an upper limit pressure and a lower limit pressure are set, respectively, and compared with the output of the integrator 10, a control signal is generated. However, comparator 12
is made to have a low potential when the output of the integrator 10 is higher than the set value, and a high potential when it is lower,
Further, the comparator 14 is configured to have a low potential when the output of the integrator 10 is lower than a set value, and to have a high potential when the output is higher than the set value. Furthermore, the oscillator 20 is NAND
It oscillates when the output of the gate 18 becomes a high potential, and the output of this oscillator 20 is sent to the addition/subtraction counter 16.
At the same time, the addition/subtraction counter 16 operates in addition mode or subtraction mode as appropriate depending on its set state, and outputs a digital signal D corresponding to the content.
Output.

To explain the operation of the addition/subtraction counter 16 in more detail, the addition/subtraction counter 16 is preset to an initial value E as an initial state by inputting a preset signal (PR), and the addition/subtraction counter 16 receives the preset digital signal D (=E). ) is output. In this case, if the output of the integrator 10, that is, the average value of the measured pressure is within the range set in the comparators 12 and 14, the outputs of the comparators 12 and 14 are all at high potential, and as a result, the NAND gate 18 The output becomes a low potential, the oscillator 20 does not operate, the contents of the addition/subtraction counter 16 are held, and the pump continues in the same operating state.

When the output of the integrator 10 is lower than the lower limit value set in the comparator 14, the output of the comparator 12 becomes a high potential, the output of the comparator 14 becomes a low potential, and the output of the NAND gate 18 becomes a high potential. The oscillator 20 oscillates, and the addition/subtraction counter 16 reaches U/
Since the D input is at a high potential, the addition mode is entered, and the output pulse of the oscillator 20 is used as a clock pulse to increase its content (digital signal D) by one. As a result, the content of the add/subtract counter 16 increases and the pump is modified to increase pressure. Therefore, this operation continues until the output of the integrator 10 falls within the pressure range set by the comparators 12 and 14.

Further, when the output of the integrator 10 is higher than the upper limit value set in the comparator 12, the output of the comparator 12 becomes a low potential, the output of the comparator 14 becomes a high potential, and the output of the NAND gate 18 becomes a low potential. becomes a high potential, the oscillator 20 oscillates, and the addition/subtraction counter 16
is in subtraction mode because the U/D input is low potential,
The output pulse of the oscillator 20 is used as a clock pulse, and its content (digital signal D) is decreased by one. As a result, the content of the add/subtract counter 16 decreases and the pump is modified to reduce pressure. Therefore, this operation continues until the output of the integrator 10 falls within the pressure range set by the comparators 12 and 14.

As is clear from the above description, the digital signal D from the addition/subtraction counter 16 can be used to operate an appropriate pump drive control circuit to adjust the pump discharge amount and control the discharge pressure.

In this case, the method for adjusting the discharge pressure amount is as follows:
A method of adjusting the flow rate and a method of adjusting the pulsation rate when the infusion pattern is pulsatile can be adopted.

Next, a drive control circuit for an infusion pump suitable for applying the device of the present invention will be described by way of example. The pump used in this example includes a pump section, a motor for driving the pump section, and a motor that is driven to rotate in a rotation mode consisting of adjustable acceleration, first constant speed, deceleration, and second constant speed. and a control circuit configured to perform pumping operations in an infusion pattern. The pump section is constructed by winding an elastic tube around a rotating body having a plurality of rollers, and a pulse motor is used as the motor.

Therefore, as shown in FIG. 2, the control circuit described above includes oscillators 110, 112, and 114 that set acceleration, first constant speed, and deceleration times, respectively, an oscillator 118 that sets the cycle of the rotation mode, and a state counter 128 that instructs the addition or subtraction operation to the addition/subtraction counter 130; an addition/subtraction counter 130 that adds or subtracts the signal from the oscillator according to the commands of the state counter; A frequency converter 138 that converts into a pulse signal, a comparator 162 that inputs an adjustable bias component and compares this bias component with the contents of an addition/subtraction counter, and an acceleration time and deceleration time that do not change when adjusting the bias component. Frequency correction circuits 138, 160 that maintain
and monostable multivibrators 132, 146, 14 that generate actuation timing pulses for each device.
8, 150, 154, 156 and pulse motor drive circuits 140, 142, 144.

In addition, reference numeral 116 is a pulse motor,
120 is an oscillator that determines the maximum infusion volume. Furthermore, the circuit of this embodiment includes a flip-flop 12.
6, frequency divider 122, 124, OR gate 134,
136, 152, 164 and AND gate 16
6,168 are provided respectively.

To briefly explain the operation of the drive control circuit configured in this way, first, in the initial state, the frequency dividers 122, 124, the flip-flop 126,
Status counter 128 and addition/subtraction counter 130 have all been reset. In this case, all the oscillators 110, 112, 114, 118, 120 are not activated and the pulse motor is not driven, so no pumping operation is performed.

Next, by inputting the start signal A, the oscillator 1
18, 120 are activated and the status counter 12
8, the oscillator operates, and the addition/subtraction counter 130 performs addition operation in addition mode, resulting in
Motor drive circuits 140, 142, and 144 controlled by the output of addition/subtraction counter 130 accelerate rotation of pulse motor 116. When the contents of the addition/subtraction counter 130 reach the maximum, the status counter 12
The oscillator 112 operates by advancing the contents of 8 by one.
The output signal of this oscillator 112 is the state counter 1
The contents of 28 are advanced by one, but the addition/subtraction counter 130 does not operate and its contents are kept at the maximum, so the rotation of the pulse motor does not change (first constant speed rotation). The content of the status counter 128 is 1
When the signal advances to one step, the oscillator 114 is activated. This oscillator 1
The output signal 14 is inputted as a clock to the addition/subtraction counter 130, and the addition/subtraction counter 130 performs a subtraction operation in a subtraction mode, and as a result, the pulse motor 116 is decelerated. When the output of the addition/subtraction counter 130 matches the bias value C set in the comparator 162, the contents of the state counter 128 are incremented by one, the frequency divider 122, the state counter 128, and the addition/subtraction counter 130 are reset. A bias value C is input to the pulse motor drive circuit until the next cycle of operation mode by a timer consisting of an oscillator 118 and a frequency divider 124, and the pulse motor performs constant rotation (second constant speed rotation).

However, when incorporating the discharge pressure control device according to the present invention shown in FIG. The flow rate of the pump can be adjusted based on the digital signal D by providing a frequency converter that converts the digital signal D into a frequency converter and replacing this frequency converter with the maximum infusion volume setting oscillator 120 shown in FIG.

Furthermore, by replacing the frequency converter with the period setting oscillator 118 shown in FIG. 2, the pump pulsation rate can be adjusted based on the digital signal D.

Furthermore, the frequency converter is replaced with the maximum infusion volume setting oscillator 120 and the period setting oscillator 118 shown in FIG. can be controlled.

Note that when a digital signal converter is installed in place of the maximum infusion volume setting oscillator 120 or the cycle setting oscillator 118 described above, each initial value is set in the addition/subtraction counter 16 by a preset signal, and the values are calculated from this addition/subtraction counter 16. The output digital signal D is supplied to a frequency converter 22 as shown in FIG. 3, where it is converted into a pulse train with a frequency proportional to the magnitude of the signal D. It is preferable to configure the circuit so that the pulse is generated and the output of the frequency converter 22 is smoothed through the smoother 26 to shape the pulse.

As is clear from the above, according to the device of the present invention, the discharge amount can be adjusted so as to maintain the pump discharge pressure or perfusion pressure constant without being affected by instantaneous pressure fluctuations on the load side. .

Although the preferred embodiments of the present invention have been described above, it goes without saying that various design changes can be made without departing from the spirit of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a block control circuit diagram showing the basic configuration of a discharge pressure control device for an infusion pump according to the present invention;
Figure 2 is a block circuit diagram showing one embodiment of a pump drive control circuit to which the device of the present invention is applied, and Figure 3 is a block circuit diagram of a signal converter used when incorporating the device of the present invention into the pump drive control circuit. be. 10... Integrator, 12, 14... Comparator, 16
...Addition/subtraction counter, 18...NAND gate, 2
0... Oscillator, 22... Frequency converter, 24...
Fundamental frequency oscillator, 26...Smoother, 110...
Oscillator for acceleration rotation control, 112... Oscillator for first constant speed rotation control, 114... Oscillator for deceleration rotation control, 116... Pulse motor, 118... Oscillator for period setting, 120... Maximum infusion amount setting oscillator,
122, 124... Frequency divider, 126... Flip-flop, 128... Status counter, 130...
Addition/subtraction counter, 132, 146, 148, 15
0,154,156...monostable multivibrator, 134,136,152,164...OR gate, 138...frequency converter, 140,14
2,144...Motor drive circuit, 158...Frequency converter, 158,160...Frequency correction circuit,
162... Comparator, 166, 168... AND gate.

Claims (1)

[Claims] 1. Means for measuring and averaging the pump discharge pressure, means for comparing the averaged measured pressure with a predetermined set pressure, and means for measuring the measured pressure within the range of the set pressure. is a counter that generates a constant signal and generates a signal that increases or decreases by performing addition mode or subtraction mode operation when the measured pressure is lower or higher than the set pressure, and depending on the output of this counter. 1. A discharge pressure control device for an infusion liquid injection pump, comprising a control circuit that adjusts a pump discharge amount. 2. The means for measuring and averaging the pump discharge pressure is constituted by an integrator.
Discharge pressure control device as described in . 3. The means for comparing the measured pressure and the set pressure consists of a pair of comparators connected in parallel, each setting an upper limit pressure and a lower limit pressure, and generates a clock pulse when the measured pressure falls outside the range of the set pressure. 3. A discharge pressure control device according to claim 1, wherein the discharge pressure control device is configured to energize an oscillator and perform addition/subtraction on a counter using a clock pulse. 4 The counter consists of an addition/subtraction counter, which can be selectively set to addition mode, subtraction mode, or arithmetic stop state by the output of the comparator, and any initial value can be set by a preset signal. or the discharge device according to any one of claims 1 to 3, configured to output the respective digital signals after the subtraction is performed, and to output a predetermined setting signal when the calculation is stopped. Pressure control device. 5. The control circuit that adjusts the pump discharge amount includes a frequency converter that converts the output signal of the counter into a pulse train with a frequency proportional to the magnitude of the output signal, and a circuit that drives and controls the pump driving pulse motor using the pulse train as a control signal. A discharge pressure control device according to any one of claims 1 to 4, comprising: 6 The control circuit that adjusts the pump discharge amount controls acceleration,
an oscillator that sets constant speed and deceleration times, a status counter that commands the operation of each oscillator and instructs an addition or subtraction operation to an addition/subtraction counter, and an addition/subtraction counter that adds or subtracts signals from the oscillator according to commands from the status counter; A frequency converter that converts the contents of the addition/subtraction counter into a pulse signal with a frequency proportional to the content, a monostable multivibrator that generates the activation timing pulse for each device, an oscillator that sets the maximum infusion volume, and a pulse motor drive circuit. A discharge pressure control device according to any one of claims 1 to 5. 7 The control circuit that adjusts the pump discharge amount controls acceleration,
An oscillator that sets the constant speed and deceleration time, an oscillator that sets the period of rotation mode, a status counter that commands the operation of each oscillator and instructs the addition or subtraction operation to the addition/subtraction counter, and a an addition/subtraction counter that adds and subtracts signals, a frequency converter that converts the content of the addition/subtraction counter into a pulse signal with a frequency proportional to the content of the addition/subtraction counter, a monostable multivibrator that generates operating timing pulses for each device, and a pulse motor drive circuit. A discharge pressure control device according to any one of claims 1 to 5.