JPS642387B2 - - Google Patents

Description

[Detailed description of the invention]

[Object of the Invention] (Industrial Application Field) The present invention relates to an artificial heart pump drive device for driving an artificial heart pump, which is an auxiliary circulation device for medical use. (Prior Art) Conventionally, in order to treat diseases of the circulatory system of a living body, devices have been developed that assist the heart of the living body using, for example, an auxiliary artificial heart. As an example of this type of device, a drive device that generates pressure pulses to drive an artificial heart pump is proposed, for example, in a patent application filed in 1983.
-Disclosed in Publication No. 169460. In this type of drive device, a compressor generates positive pressure and a vacuum pump generates negative pressure, the positive pressure and negative pressure are stored in tanks for positive pressure and negative pressure, respectively, and the solenoid valves are used to generate positive and negative pressure. By alternately switching the pressure supply, pressure pulses are generated and supplied to the artificial heart pump. (Problems to be Solved by the Invention) In conventional devices, for example, when switching the supply pressure to an artificial heart pump from negative pressure to positive pressure, communication from the negative pressure tank to the artificial heart pump is cut off, and when the supply pressure to the artificial heart pump is switched from negative pressure to positive pressure, Open communication from to the artificial heart pump. When the connection from the positive pressure tank to the artificial heart pump is opened, since negative pressure is generally accumulated in the artificial heart pump, it takes time until the necessary positive pressure is supplied to the artificial heart pump. The same applies when switching from positive pressure to negative pressure. In this way, the rising and falling waveforms of the pressure pulses supplied to the artificial heart pump become gentle.
Due to this rounding of the waveform, even if the pressure pulses are switched accurately, there will be some fluctuation in the flow rate of fluid supplied to the artificial heart pump when positive pressure is applied. Fluctuations in the flow rate occur not only in the above case but also depending on the wiring between the drive device and the artificial heart pump and the condition of the living body. Variations in the flow rate to the artificial heart pump directly result in variations in the flow rate of blood passing through the artificial heart pump. A number of problems arise when the flow rate of blood through an artificial heart pump increases or decreases. For example, when using an artificial heart pump to assist the right heart, if the amount of blood ejected by the artificial heart pump is large,
Since the amount of blood ejected from the left side of the heart is fixed, too much blood may accumulate in the lungs, leading to pulmonary edema. In addition, if the flow rate of blood passing through an artificial heart pump is low, for example when an artificial valve is attached to the aortic valve of a living heart, blood clots are likely to form, and blood circulation to other organs cannot be maintained. become unable. Therefore, an object of the present invention is to stabilize the flow rate of blood pumped by an artificial heart pump. [Structure of the Invention] (Means for Solving the Problems) The means taken in the present invention to solve this problem include a positive pressure source, and a positive pressure switch whose one end is connected to the output end of the positive pressure source. a negative pressure switching solenoid valve, one end of which is connected to the output end of the negative pressure source, and the other end of which is connected to the other end of the positive pressure switching solenoid valve;
An artificial heart pump comprising electronic control means for controlling opening and closing of the positive pressure switching solenoid valve and the negative pressure switching solenoid valve, and driving the artificial heart pump by a pressure pulse generated at the other end of the positive pressure switching solenoid valve. In the drive device, a setting means for setting a blood flow rate ejected per operation of the artificial heart pump, and a flow rate detection sensor disposed at an output end of the artificial heart pump to detect the blood ejection flow rate of the artificial heart pump. , and a flow rate accumulating means for accumulating the blood flow rate detected by the flow rate detection sensor after the electronic control means opens the positive pressure switching solenoid valve, and the cumulative flow rate of the flow rate accumulating means is set by the setting means. The positive pressure switching solenoid valve is closed when the flow rate exceeds the set flow rate value. (Operation) According to the means of the present invention, when the positive pressure switching solenoid valve is opened, the driving fluid is sent to the artificial heart pump,
Blood is ejected, but when the cumulative amount of blood ejected by the artificial heart pump exceeds the blood flow rate set by the setting means when positive pressure is applied, the positive pressure switching solenoid valve is closed, and the driving fluid to the artificial heart pump is closed. Sending is stopped.
Therefore, the flow rate of blood ejected by the artificial heart pump remains constant each time it ejects. (Embodiment) A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a circulatory system, and the circulatory system has an artificial heart pump 11 as a main body. artificial heart pump 1
1 is provided with a positive pressure side system for compression and a negative pressure side system for expansion, which are biasing means. Then, positive pressure or negative pressure is alternately supplied from the positive pressure and negative pressure systems, and the artificial heart pump 11 repeatedly operates. Further, a flow rate detection sensor 11a is attached to the outflow side of the circulatory system main body 11. The positive pressure side system includes an air pump 1 that is a positive pressure generation source, a pressure accumulator 7 that accumulates the positive pressure from the air pump 1, and a normally closed solenoid valve that is a driving on-off valve that connects the pressure accumulator 7 with an artificial heart pump 11. 4. Further, the positive pressure side system is provided with a normally closed solenoid valve 3 which is a supply on-off valve that communicates the air pump 1 with the pressure accumulator 7, and a pressure sensor that detects the positive pressure value accumulated in the pressure accumulator 7. A sensor 9 is attached. Similarly, the negative pressure side system includes a vacuum pump 2 as a negative pressure generation source, a pressure accumulator 8 that accumulates negative pressure from the vacuum pump 2, and an artificial heart pump 1
1, a normally closed solenoid valve 3 is a driving on-off valve that communicates with the vacuum pump 2, and a normally closed solenoid valve 6 is a supply on-off valve that connects the vacuum pump 2 with the pressure accumulator 8. A pressure sensor 10 is attached to detect the negative pressure value. In positive and negative pressure systems, the supply solenoid valves 3 and 6 open when the pressure in the pressure accumulators 7 and 8, measured by pressure sensors 9 and 10, respectively, decreases (absolute value). Positive or negative pressure sources 1 and 2 for 7 and 8
Replenish operating pressure from. The opening and closing operations of the electromagnetic valves 3 and 6 are controlled by a control unit CPU (control means), which will be described later, but detailed explanation thereof will be omitted. The above-mentioned circulatory system is controlled and operated by the control device shown in FIG. The control device has a microcomputer CPU as a control section, and the microcomputer CPU is connected to a set value switch section 13 and pressure sensors attached to the pressure accumulators 7 and 8 via interfaces (not shown), respectively. 9, 10, a series of solenoid valves 3,
4, 5, 6 and a monitor 14 are connected.
Furthermore, a flow rate detection sensor 11a that detects the outflow flow rate from the circulatory system main body 11 via the amplifier 12, and a pulsation detection device that detects the pulsation timing (ECG processing waveform) of the heart of the living body from an electrocardiogram (ECG waveform).
The ECG is also connected to the control CPU (see Figure 2). The set value switch section 13 sets a time interval SYS0 from closing to opening of the driving solenoid valve 5. At this time interval, the valve opening timing of the drive solenoid valve 4 and the maximum allowable valve opening time interval SYS0 are set (second
(see figure). Furthermore, the set value switch section 13 has a function of setting the outflow flow rate Ql/min per minute. Further, a delay time delay0 from the start of pulsation of the heart of the living body to the start of pulsation of the artificial heart pump 11 is also set. Next, the processing flow built into the control unit CPU will be explained. The processing flow is the main flow (Figure 4), 1m
Timer interrupt flow processed every sec (6th
(Fig. 5), and a setting value flow (Fig. 5) that is interrupted every time the pulse detection device ECG detects the pulsation of the living heart. Each flow has flags summarized in the table below,
It has a counter and memory.

【table】

【table】

[Table] First, in the main flow, when started, initialization (not shown) is performed. This initialization sets flag C to 00. If flag C is 00 at step S1 (YES), from the next step onwards,
Calculate the number of pulsations per minute N (times/min) at the current time i based on the biological heart pulsation time R interval TR of the previous 8 beats, take in the set flow rate Q, and calculate the number of pulsations per minute N
(times/min) and the set flow rate Q, based on the following calculation formula qi = Q × 1000/N (cc), the flow rate i per pulsation at the current time i
calculation, and also the maximum allowable opening time interval of solenoid valve 4.
Import SYS0 and delay0. After that, the flag C is changed to 01 and the process returns to the beginning of the main flow. In step 1, if flag C is 01, no special processing is performed (NO) and the system is in a standby state. During main flow processing, pulsation detection device
When a pulsation detection signal is input from the ECG, the set value flow is executed. When started, the value TR corresponding to the pulsation time interval at the previous time i-1 is first stored in the memory TR'.
The memory TR' is composed of a shift register and stores eight pulsation time intervals TR from the present to the past.
Based on the past TR value stored in this memory TR', the number of pulsations per minute N (times/min) at the current time i is calculated in the main flow. Furthermore, the memory TR is set to 00, and then the set delay time delay0 is set and the counter delay is set to 0. After that, return to the main flow. Similarly, a timer interrupt flow is executed every 1 msec during main flow processing. When starting, counter TR is 1 (i.e. 1m)
sec) is counted up. Next, step S2
So, set delay time delay0 and delay time counter
Compare with the count value of delay. While the count value of the delay time counter delay is smaller than the delay setting time delay0 (NO), the delay time counter delay is set to 1.
(i.e., 1 msec), and the latter step described later is processed. When the count value of the delay time counter delay becomes larger than the delay setting time delay0 (YES), the step
In S3, the flag 2 for opening the solenoid valve 4 is determined, and if the flag 2 is 01 (YES), the next process is executed. First, the maximum allowable opening time interval of solenoid valve 4
Set SYS0, counter SYS for valve opening time interval,
The outflow flow rate memory qc after the flow rate matching point Tc and the outflow flow rate memory q after the start of pulsation are each set to 0. Further, flags 0, 1, 2, and C for 2 msec, outflow flow rate matching point, valve opening, and calculation are set to 00, respectively. Moreover, the measured flow rate value qc (i-1) after passing the coincident point TR, which is measured in the latter half of the flow described later.
(measured value during the previous pulsation) and the calculated current i
The difference between the outflow flow rate qi and the outflow flow rate qi per time is set in the memory qs(i) as the set outflow flow rate qs(i) when the valve is opened this time i. Furthermore, since the preset delay time delay0 has elapsed, the electromagnetic valves 4 and 5 are opened and closed, respectively, so that the artificial heart pump 11 is pulsated. In the second half of the interrupt flow, in order to prevent the opening time of the solenoid valve 4 from exceeding the maximum allowable time SYS0, first, in step S4, the valve opening time interval counter SYS is incremented by 1 (ie, 1 msec). Next, in step S5, the maximum allowable time SYS0 is compared with the count value of the valve opening time interval counter SYS. When the count value of the valve opening time interval counter SYS becomes larger than the maximum allowable valve opening time interval SYS0 (YES), the open solenoid valve 4 is closed and the closed solenoid valve 5 is opened. . This results in
Since negative pressure is applied to the artificial heart pump 11 instead of positive pressure, the outflow of fluid is stopped and one operation is completed. While the count value of the valve opening time interval counter SYS is smaller than the maximum allowable valve opening time interval SYS0 (NO),
Check whether flag 0 for 2msec timer is 01 or not.
It is determined in step S6. The flag 0 is 01
If (YES), set the flag 0 to 00, and set the flag 0 to 00.
If it is 01, reset it to 00. Furthermore, in step S8,
It is determined again whether flag 0 is 01 or not, and if flag 0 is 00 (NO), the process returns to the main flow. If flag 0 is 01, it is determined based on flag 1 whether or not it is before passing the matching point TR. If flag 1 is 00 (before passing TR, YES), memory q
Add the flow rate qk at the current moment i to . This results in
The flow rate flowing out is measured after the set delay time delay0. In step S9, if the measured flow rate q matches the flow rate value qs(i) during the set valve opening time (YES), the solenoid valve 4 is closed even if the maximum allowable valve opening set time interval has not been reached. Additionally, set flag 1 to 01
, and the state where the flow rate matching point TR has been passed is shown. However, after passing the flow rate matching point TR, flag 1 is set.
is set to 01 (determined as NO in step S8), henceforth, the flow rate qc(i) after passing the matching point TR is measured by adding the flow rate qk at the current time i to the memory qc(i). The measurement of the flow rate qc(i) is continued until the flag 1 is set to 00 with the next opening of the solenoid valve 4 i+1. Such an outflow flow rate qs(i) or
After measuring qc(i), return to the main flow. In addition, in steps S7 and S8, the value of the 2 msec flag 0 is set every timer interrupt flow processing (1 msec).
Since they are exchanged between 00 and 01, the outflow flow rates qs(i) and qc(i) are measured every 2 msec sampling time (see Figure 3). The embodiment of the present invention constructed as described above operates as follows (see FIG. 2). First, when the control unit CPU operates, the average outflow flow Ql/min per minute required by the living body, which is set by the set value switch unit 13, and the operation of the driving solenoid valves 4 and 5, that is, the artificial heart pump 11 The maximum allowable valve opening time interval SYS0, which corresponds to the compression period of , and the delay time delay0 until the operation of the artificial heart main body 11, that is, the opening of the electromagnetic valve 4 after the pulsation of the heart of the living body, are respectively taken in (FIG. 4). Maximum allowable valve opening time interval SYS0 and delay time
The opening timing of the solenoid valve 4 and the opening/closing timing of the solenoid valve 5 are determined from delay0. Regarding the closing of the electromagnetic valve 4, the timing is controlled so that the set outflow amount Q can be achieved. For the control unit CPU in this state,
When there is a pulsation in the living heart, the pulsation is detected by a pulsation detection device.
When the ECG is detected and the ECG processing waveform, which is the timing Ri, falls, the set value flow is interrupted and the current i pulsation period is started. In the set value flow, the count value of the counter TR corresponding to the previous pulsation period i-1 is taken into the shift register TR'. In order to measure the pulsation period of i this time, we set the counter TR to 0 and set the delay time
Set delay0 in memory. shift register
TR' stores eight past pulsation periods TR including the previous time i-1. In the main flow, 8 pulsation periods TR until the previous time
From this, the number of pulsations per minute N of the living heart at the current time i is calculated, and the outflow flow rate qi at the current time i necessary to obtain the set flow rate Q is determined. In the 1 msec interrupt flow, the counter TR is incremented by 1 for each interrupt to measure the pulse interval of this time i. Further, the counter delay is also incremented by 1, and the CPU waits until the counter delay reaches the set delay time delay0 (step S2). When the counter delay reaches the set delay time delay0,
The electromagnetic valves 4 and 5 are opened and closed, respectively, to cause the artificial heart pump 11 to perform a compressing operation, that is, to cause fluid to flow out. At the same time, the flow rate qi that should flow out during the pulsation period at this time i and the flow rate qc that flowed out after the solenoid valve 4 was closed in the previous time i-1, that is, after the compression of the artificial heart pump 11 was stopped.
(i-1) is calculated (step S31). Furthermore, when this differential flow rate qs(i) flows out, solenoid valve 4
The remaining flow rate is secured as an outflow flow rate that naturally flows out after the solenoid valve 4 is closed. As long as the condition of the living body does not suddenly change, approximately the same outflow flow rate will be obtained after closing the solenoid valve in the previous i-1 and this time i, so the flow rate
Even if the solenoid valve 4 is closed based on qs(i) (step S91), the required flow rate qi of the current time i can be accurately flowed out. Based on the measured value from the flow rate detection sensor 11a,
The flow rate after the solenoid valve 4 is opened is measured in the memory q (step S81), and when the value in the memory q becomes the flow rate value qs(i) that should flow out while the solenoid valve 4 is opened this time (step
S91), closes the solenoid valve 4. When the solenoid valve 4 closes, based on the measured value from the flow sensor 11a, the flow rate from the time the solenoid valve 4 closes to the next i+1 opening is measured in memory qc(i) (steps S8, 82), Outflow flow rate qs from opening to closing of solenoid valve 4 at
Used to calculate (i+1). When the maximum allowable opening interval SYS0 of the solenoid valve 4 is reached, the solenoid valve 5 is always opened and even if the outflow flow rate is insufficient, the solenoid valve 4 is closed (steps S51 and 52). The artificial heart pump 11 enters the inflation operation. After that, this operation is repeated until the artificial heart pump 1
1 and continue to flow out the fluid in a pulsating manner. As explained above, according to the present invention, the flow rate of blood ejected by the artificial heart pump becomes constant and stable each time it ejects. Therefore, it becomes possible to restore the heart of the living body without affecting other organs.

[Brief explanation of drawings]

FIG. 1a is a block diagram showing the system of the drive device according to the invention, FIG. 1b is a block diagram showing the control section of the drive device according to the invention, and FIG. 2 is a timing cheat showing the operating state of the drive device according to the invention. FIG. 3 is an explanatory diagram showing a method of measuring the outflow flow rate, and FIGS. 4 to 6 are a main flow, an interrupt flow, and a set value flow showing the operation of the control section. 1... Positive pressure source (positive pressure source), 2... Negative pressure source (negative pressure source), 3, 6... Solenoid valve, 4... Positive pressure side drive solenoid valve (positive pressure switching solenoid valve), 5... Solenoid valve for negative pressure side drive (solenoid valve for negative pressure switching), 7, 8... Pressure accumulator,
9, 10...Pressure sensor, 11...Artificial heart pump, 11a...Flow rate detection sensor, 12...Amplifier, 13...Setting switch section (setting means), CPU
...control means (electronic control means, flow rate accumulation means),
ECG...pulsation detection device.

Claims (1)

[Claims] 1 A positive pressure source, one end of which is connected to the output end of the positive pressure source, a positive pressure switching solenoid valve, a negative pressure source, one end of which is connected to the output end of the negative pressure source, and the other end of which is connected to the positive pressure switching solenoid valve. A negative pressure switching solenoid valve connected to the other end of the solenoid valve, and
An artificial heart pump comprising electronic control means for controlling opening and closing of the positive pressure switching solenoid valve and the negative pressure switching solenoid valve, and driving the artificial heart pump by a pressure pulse generated at the other end of the positive pressure switching solenoid valve. In the drive device, a setting means for setting a blood flow rate ejected per operation of the artificial heart pump, and a flow rate detection sensor disposed at an output end of the artificial heart pump to detect the blood ejection flow rate of the artificial heart pump. , and a flow rate accumulating means for accumulating the blood flow rate detected by the flow rate detection sensor after the electronic control means opens the positive pressure switching solenoid valve, and the electronic control means is configured to accumulate the blood flow rate detected by the flow rate detection sensor after the electronic control means opens the positive pressure switching solenoid valve. An artificial heart pump driving device that closes the positive pressure switching solenoid valve when the cumulative flow rate exceeds a set flow rate value of the setting means.