JPH0775670A - Pressure limiter for syringe pump - Google Patents

Abstract

PURPOSE:To automatically close a liquid chemical flow passage so as to protect a patient when the liquid pressure of transfusion rises to a specified pressure or above. CONSTITUTION:A valve 25 having a valve disk 25a and a valve seat 25b is disposed in mid-way of the liquid chemical flow passage from an inlet pipe 22 to an outlet pipe 23 of the pressure limiter 4. This valve 25 is operated to be closed by a diaphragm 26 which receives the liquid pressure on the upstream side thereof. This diaphragm 26 is lifted by overcoming the force of a back spring 29 to press the valve disk 25a to the valve seat 25b and to close the flow passage 24 when the downstream side is clogged during transfusion and the liquid pressure rises to the specified pressure or above. As a result, the supply of the liquid chemical to the downstream side is shut off and the danger that the liquid pressure higher than the specified pressure acts on the patient is prevented. The liquid pressure on the upstream side increases more when the flow passage 24 is closed. This liquid pressure acts to more close the valve 25.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a syringe pump for pushing a drug solution in a syringe barrel with a piston to inject it into a human body, and more particularly to a syringe pump pressure limiter for suppressing an excessive increase in the pressure of the drug solution.

[0002]

2. Description of the Related Art When a syringe pump injects (injects) a medicinal solution into a human body, if the pressure generated by the syringe pump is too large, the human body is in danger when the injection needle comes off the blood vessel. Therefore, the syringe pump is required to be provided with a means for stopping the infusion when the fluid pressure rises above a certain level during the infusion.
In that case, a mechanism that indirectly detects a rise in hydraulic pressure due to an increase in drive resistance of the syringe pump is conceivable, but this is not a good idea as described below.

The drive resistance of the syringe pump is the hydraulic resistance determined by the product of the pressure of the drug solution inside the syringe and the cross-sectional area of the syringe, the mechanical resistance of the drive mechanism, and the frictional force between the syringe barrel and the piston of the syringe. Syringe resistance based on is added. Of these, the mechanical resistance can be reduced to such an extent that there is practically no problem, but the syringe resistance varies greatly depending on the manufacturing lot, the outside temperature, etc., and it is difficult to accurately predict this value to some extent.

That is, FIG. 13 shows an example of measuring the syringe resistance, that is, the time change of the force when the piston of the syringe is pushed, for two samples (1, 2). As described above, the variation in resistance between samples is large, and the difference between the maximum and the minimum may reach 5 kgf or more. This variation exceeds the allowable range of increase in hydraulic pressure from the viewpoint of protecting the human body, and it is impossible to control the hydraulic pressure from the drive resistance of the syringe pump including such an uncertain factor.

[0005]

On the other hand, as a means for directly detecting the pressure of an infusion to report an abnormality, Japanese Patent Publication No. 1-32
There is a pressure detector described in Japanese Patent No. 611. this is,
The change in the pressure in the pipe is taken out through the flexible film, and when this pressure exceeds a predetermined threshold value, the electric contact is switched to generate an electric signal.

However, this pressure detector is built in a syringe pump, and a dedicated electric circuit is used to stop the drive source of the syringe pump or to generate an alarm by the obtained electric signal. Since it is necessary, it cannot be applied to an existing syringe pump as a single body.
Therefore, an object of the present invention is to provide a syringe pump pressure limiter that can be easily externally attached to any syringe pump and can reliably stop the infusion when the pressure of the infusion rises above a certain value. It is what

[0007]

A pressure limiter of the present invention receives a valve that opens and closes a drug solution flow path from a syringe pump to an injection needle, and receives a fluid pressure on the upstream side of this valve so that this fluid pressure is constant. And a pressure-receiving means for closing the valve when the temperature rises.

[0008]

In the pressure limiter of the present invention, the pressure receiving device receives the liquid pressure of the chemical liquid flow path from the syringe pump to the injection needle, and when the liquid pressure rises to a constant pressure, the valve that opens and closes the chemical liquid flow path is used. It closes and shuts off the liquid medicine, preventing the liquid pressure above a certain pressure from being applied to the human body. When the valve closes, the hydraulic pressure on the upstream side increases more and more, so the pressure receiving device that receives this hydraulic pressure acts to further close the valve. Such a pressure limiter mechanically shuts off the chemical liquid in response to an increase in the liquid pressure, so that the operation is quicker than the case where the drive source of the syringe pump is stopped by an electric signal, and the structure is simple and Since it does not require a dedicated electric circuit, it can be easily applied to existing syringe pumps.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a vertical cross-sectional view showing a valve of a pressure limiter showing an embodiment of the present invention, FIG. 2 is a view showing a state in which the valve is closed, and FIG. FIG. 4 is a perspective view showing the external appearance of the syringe pump, FIG. 4 is a vertical cross-sectional view showing the drive mechanism portion thereof, and FIG. 5 is a control block diagram for causing the syringe pump to generate an alarm. First, in the syringe pump of FIG. 3, the syringe (syringe) 2 is held on the upper surface of the pump body 1, and the drug solution in the syringe barrel 2a is infused into the patient from the injection needle (not shown) by pushing the piston 2b. The pressure limiter 4 according to the present invention is inserted between the liquid medicine discharge port 2c of the syringe 2 and the infusion tube 3.
The injection needle is connected to a tip portion (not shown) of the tube 3.

A drive mechanism for driving the syringe 2 is provided inside the pump body 1 as shown in FIG. In FIG. 4, the motor 5 started by the start of infusion rotates the feed screw 7 via the pair of gears 6 and moves the half nut 8 meshing with the feed screw 7 to the right in the figure. The housing 8a holding the half nut 8 is connected to a pusher 10 via a tubular connecting rod 9, and the pusher 10 moves integrally with the half nut 8 to push the piston 2b. An operating rod 11 having a handle 11a is housed in the connecting rod 9,
Its tip is connected to the half nut 8. The half nut 8 that has advanced to the right end in the figure after the completion of the infusion is removed from the feed screw 7 by the rotation operation of the operation rod 11 by the handle 11a, and is pulled back to the left end again.

Both ends of the feed screw 7 are supported so as to be freely movable in the axial direction, and the free end of a leaf spring 12 cantilevered at the lower end is made of resin on the left end face in the figure. Are in contact with each other via the sliding piece 13. A strain gauge 14 is attached to the surface of the leaf spring 12 in the figure. When infusion is performed under such a configuration, the feed screw 7 is pushed and moved leftward in the drawing by the reaction force from the half nut 8 to bend the free end of the leaf spring 12.
As a result, an output is generated from the strain gauge 14, and this output is proportional to the drive resistance received by the drive mechanism, so that when this becomes excessive, it can be determined that an abnormality has occurred. That is, in FIG. 5, after the output of the strain gauge 14 is amplified by the amplifier circuit 15, the comparison circuit 16 compares it with the reference voltage from the reference voltage generation circuit 17 to check whether or not this has been exceeded. The generation circuit 18 is activated.

Now, the pressure limiter 4 will be described in detail with reference to FIGS. 1 and 2. In the figure, the pressure restrictor 4 is divided into an inlet chamber 20 having a cylindrical space inside a disc-shaped main body 19 and a valve chamber 21 having a cylindrical space having a smaller diameter than that, and the inlet pipe is connected to each of these. Two
2 and an outlet pipe 23 are provided. The inlet pipe 22 has a tapered hole that fits with the outer diameter of the injection needle mounting port 2c (FIG. 3) of the syringe 2, and the outlet pipe 23 has a tapered outer diameter of the same shape and size as the injection needle mounting port 2c. ing. And the entrance room 20
The flow path 24 between the valve chamber 21 and the valve chamber 21 is opened and closed by the valve 25. The valve 25 has a disc-shaped valve body 25a housed in the valve chamber 21, and an annular valve seat 25b facing the valve body 21 is integrally formed with the main body 19. A packing 25c is mounted between the valve body 25a and the valve seat 25b.

The upper surface of the inlet chamber 20 is closed by a circular diaphragm 26 whose periphery is adhered to the main body 19, and the upper surface thereof is a release button 27 which is a cylindrical cylinder with a collar which also serves as a reinforcing plate.
Are glued together. The head of the release button 27 is exposed to the outside through a round window 28a of a gate-shaped cover 28 adhered to the main body 19 so as to straddle the diaphragm 26. A back spring 29, which is a compression coil spring that presses the diaphragm 26 downward with a predetermined force, is inserted between the flange portion of the release button 27 and the cover 28.
On the other hand, the valve body 25 a is attached to a valve shaft 25 d including a cross-shaped portion that penetrates the flow path 24 and a cylindrical portion that fits into the hollow cylindrical portion of the release button 27, and the circular lid plate 30.
The valve body 25a inserted into the main body 19 from the lower opening of the valve chamber 21 in the absence thereof is connected to the release button 27 by press fitting the valve shaft 25d. The valve chamber 21 is then closed by adhering the cover plate 30 to the main body 19.

In such a pressure limiter 4, the valve 25
The liquid medicine flowing in from the inlet pipe 22 as shown by the arrow in the state where the valve is opened (FIG. 1) is supplied to the inlet chamber 20, the flow path 24 and the valve chamber 21.
Through the outlet pipe 23. Meanwhile, the fluid pressure before and after the valve 25 is the same, and the diaphragm 26 that receives this fluid pressure
Tries to be displaced upward, but in normal times, the force of the back spring 29 is predominant and the state of FIG. 1 is maintained. After that, when some kind of blockage of the chemical liquid flow path occurs downstream of the pressure limiter 4 and the liquid pressure in the flow path rises, the force applied to the diaphragm 26 increases. And this force is the back spring 2
When the force of 9 is overcome, the diaphragm 26 is lifted upward, and the valve body 25a, which is lifted accordingly, abuts the valve seat 25b to close the flow path 24, as shown in FIG.

After the flow path 24 is closed, when the chemical liquid further tries to flow from the inlet pipe 22, the chemical liquid does not flow further downstream than the valve 25, so that the hydraulic pressure on the upstream side increases more and more, and the diaphragm 26 is further increased. Close the valve 25 firmly. Therefore, if the force of the back spring 29 is set so that the diaphragm 26 is lifted at a certain hydraulic pressure determined for safety, the flow path 24 is immediately closed when the hydraulic pressure rises above this certain pressure. It is possible to promptly shut off the supply of the chemical liquid to the downstream of that. After the blockage on the downstream side is removed, in order to lower the hydraulic pressure on the upstream side, the release button 27 is pushed down to open the valve 25 or stop the syringe pump.

In the initial stage when the valve 25 is closed, the valve body 25
Although a is subjected to a force in the direction of opening the flow path 24 due to the increased hydraulic pressure on the upstream side, a slight liquid leak occurs, but since the diaphragm 26 has a larger pressure receiving area than the valve body 25a, the hydraulic pressure increases. The leakage stops with it. Further, at that time, the valve 25 reopens if the hydraulic pressure on the downstream side decreases before the hydraulic pressure on the upstream side sufficiently rises, but this characteristic is a malfunction when the hydraulic pressure on the downstream side fluctuates even in normal times. Can be actively used for prevention.

When the chemical liquid flow path is closed by the pressure limiter 4, the liquid pressure on the upstream side continues to rise, and the driving resistance of the syringe pump increases accordingly, so that the alarm generation circuit 18 operates in due course. In that case, if the drive resistance when the alarm generating circuit 18 is activated is set to be considerably higher than the level of the variation of the syringe resistance already described, there is a risk of malfunction due to confusion between the syringe resistance and the increase in hydraulic pressure. There is no. Although the pressure limiter 4 is inserted between the injection cylinder 2a and the tube 3 in FIG. 3, it may be inserted between the tube 3 and the injection needle at the tip thereof, or may be inserted in the middle of the tube 3. It can be inserted into any position of the drug solution flow path from the syringe pump to the injection needle.

FIG. 6 is a vertical cross-sectional view showing another embodiment of the pressure limiter of the present invention with the valve opened, and FIG. 7 is a view with the valve closed. In this embodiment, the pressure receiving means shown in FIG.
The bellows 31 is used instead of the diaphragm 26 in FIG. Since the bellows can easily take a larger deformation amount than the diaphragm, it is advantageous when it is desired to increase the gap when the valve 25 is opened. The rest of the configuration and operation are the same as in the first embodiment, so a description thereof will be omitted.

FIG. 8 is a longitudinal sectional view showing a further embodiment of the pressure limiter of the present invention with the valve opened, and FIG. 9 is a view with the valve closed. In this embodiment, the diaphragm 2
6 is integrally formed with the release button 27, and the diaphragm 2
The back spring is unnecessary by giving the restoring force to 6 itself. This has the advantage that the number of parts is reduced and the cost is reduced. Other configurations and operations are substantially the same as those of the two embodiments already described.

Finally, FIG. 10 is a longitudinal sectional view showing a further embodiment of the pressure limiter of the present invention with the valve opened, FIG.
1 is a view of the valve closed, and FIG. 12 is XII- of FIG.
It is sectional drawing which follows the XII line. In this embodiment, the hydraulic pressure on the upstream side acts on the valve body 25a so as to open the valve 25. That is, as shown in FIG. 12, the valve body 25a is connected to the release button 27 via a pair of left and right plate-shaped valve shafts 25d, and the chemical liquid flowing from the inlet pipe 22 into the inlet chamber 20 is connected to the valve shaft 25d and the main body 19. Through the gap 24 between the valve chamber 2
1 and further into the cylindrical passage 32, and then flows out from the outlet pipe 23. In this embodiment, the valve chamber 21 is located on the upstream side of the valve 25, and the hydraulic pressure thereof pushes the valve body 25a in the direction of closing the flow path 24, so that liquid leakage does not occur immediately after the valve 25 is closed. It is suitable when various characteristics are required.

[0021]

As described above, according to the present invention, a pressure limiter for a syringe pump opens and closes a drug solution flow path from the syringe pump to the injection needle, and receives a liquid pressure on the upstream side of the valve. By providing the pressure receiving means for closing the valve when the hydraulic pressure rises to a constant pressure, the following effects can be obtained. (1) When the fluid pressure during transfusion rises to a certain pressure, the chemical liquid passage is immediately mechanically closed, and once closed, the action further closes due to the rise in fluid pressure on the upstream side of the valve, so the operation is quick and reliable. Highly reliable. (2) Since the structure is simple and no dedicated electric circuit is required, it can be manufactured at low cost and can be easily applied to existing syringe pumps. (3) Since it can be inserted into any liquid passage between the syringe pump and the patient, a pressure limiter should be installed near the patient even if the pressure difference due to the height difference between the syringe pump and the patient poses a problem. Positioning minimizes the differential pressure.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a valve according to an embodiment of the present invention in an open state.

2 is a vertical cross-sectional view of the pressure limiter of FIG. 1 with the valve closed.

FIG. 3 is a perspective view showing an appearance of a syringe pump to which the pressure limiter of FIG. 1 is applied.

FIG. 4 is a vertical sectional view showing a drive mechanism of the syringe pump of FIG.

5 is a control block diagram for issuing an alarm to the syringe pump of FIG.

FIG. 6 is a vertical cross-sectional view of a valve according to another embodiment of the present invention in an opened state.

7 is a vertical cross-sectional view of the pressure limiter of FIG. 6 with the valve closed.

FIG. 8 is a vertical cross-sectional view of a valve according to still another embodiment of the present invention in an opened state.

9 is a vertical cross-sectional view of the pressure limiter of FIG. 8 with the valve closed.

FIG. 10 is a vertical cross-sectional view of a valve according to still another embodiment of the present invention in an opened state.

11 is a vertical cross-sectional view of the pressure limiter of FIG. 10 with the valve closed.

12 is a sectional view taken along line XII-XII in FIG.

FIG. 13 is a diagram illustrating variation in syringe resistance.

[Explanation of symbols]

 2 syringe 3 tube 4 pressure limiter 19 pressure limiter body 20 inlet chamber 21 valve chamber 22 inlet pipe 23 outlet pipe 24 flow path 25 valve 25a valve body 25b valve seat 25c packing 25d valve shaft 26 diaphragm 27 release button 28 cover 29 back Spring 31 bellows

Claims (1)

[Claims] 1. A valve comprising a valve for opening and closing a drug solution flow path from a syringe pump to an injection needle, and a pressure receiving means for receiving the fluid pressure on the upstream side of the valve and closing the valve when the fluid pressure rises to a constant pressure. A pressure limiter for a syringe pump, which is characterized in that