JPS6226070A - Infusion pump - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an infusion pump, and more particularly to a method for controlling a driven infusion pump.

[Conventional technology]

In general, infusion pumps are used in the medical field to administer nutrients intravenously to support the growth of patients who are unable to take oral intake, or who are insufficient or inappropriate for oral intake, and who require infusion nutritional management, as well as to maintain and recover their physical strength. Used for enteral supplementation. In addition, due to the recent increase in cardiac surgeries for the elderly and infants, there is an increasing demand for intraoperative and postoperative fluid nutrition management. Caution is required.

Hereinafter, liquid feeding rate refers to weight/hour or volume/time, and liquid feeding amount refers to cumulative weight or cumulative volume.Volume/time or cumulative volume is usually converted from 1 weight/hour or cumulative weight. .

Conventionally, the main types of infusion pumps are syringe type and drive type, the latter being related to the present invention, and the main types are roller type and finger type. There are two types of infusion tubes: general-purpose tubes and special-purpose tubes, and the latter is used exclusively for the infusion pump when accuracy of infusion is important. Therefore, in general, the former is general-purpose and has relatively poor accuracy but is cheap; the latter is expensive but has relatively good accuracy.

Infusion pumps and infusion tubes are appropriately selected and used in combination depending on the requirements, but there are several major problems.

First, the first problem is that the infusion tube is "sagging." That is, regardless of the selection of the infusion pump and infusion tube, the infusion tube will exhibit a ``sagging'' phenomenon due to the movement of driving the infusion tube with the infusion pump. It happens regardless of the situation. Of course, the infusion tube is "sagging".
In order to prevent this, attempts have been made to improve materials, tube dimensions, mounting methods, etc., but satisfactory results have not yet been obtained.

Therefore, the actual liquid delivery rate of the infusion pump is not constant, and the
As shown in Figures A and B, the actual liquid feeding speed and therefore the actual liquid feeding amount change with time. The degree of this change over time varies depending on conditions such as material, tube dimensions, and installation method. usually,
As shown in FIG. 5A, it gradually falls, but in some cases, as shown in FIG. 5B, it rises slightly and then falls.

As a result, not only the pre-planned infusion time is significantly deviated, but also the actual liquid delivery rate is particularly required to be constant.

A second problem that is a major problem in so-called high-precision infusions, such as infusions of blood pressure agents or infusions for infants, is "variation" in the infusion tube.

Variation in the inner diameter of the infusion tube (hereinafter referred to as "variation")
) is usually smaller in dedicated tubes than in general-purpose tubes, but there are "variations" in large and small σ.

Since this "variation" is related to the driving method of the infusion pump, it will be specifically explained.

General-purpose tubes are certainly preferred because of their low price, but because of their poor accuracy, it is insufficient to use an open system that controls the drive motor of an infusion pump at a constant rotation speed, and it is difficult to control the number of drops of drug solution. A drip control method is used that detects the amount and feeds it back to a constant number.

However, in this case, although it is possible to control one drop, if there are ``variations'' in the infusion tube (dropper nozzle), it will still lead to an error in the actual amount of liquid delivered.

On the other hand, dedicated tubes are intended to reduce the "variation" of infusion tubes and increase accuracy by making them exclusive, and are usually used in open systems.

However, even though it is a dedicated tube, it cannot be said that it is fully satisfactory considering that ``variation'' is unavoidable and the cost of using a dedicated tube is high.

The third problem is the viscosity of the chemical solution.

This problem is particularly problematic in the drip control mentioned earlier, but the volume of one drip divided by 71 tons, therefore the weight of 7 drops, varies depending on the viscosity of the drug solution, so simply controlling the number of drops will not work. The actual amount of liquid sent will differ from the set amount of liquid sent. This problem is a major problem with conventional infusion pumps because they deal with various viscosities when using a wide range of medicinal solutions. Here, the influence of the viscosity of the chemical solution includes the difference in viscosity inherent to the chemical solution and the difference in viscosity caused by temperature.

In summary, the shortcomings of infusion tubes, such as ``sagging'' and ``dispersion,'' as well as the influence of the viscosity of drug solutions, cannot be completely overcome using the open system control system or drip control system conventionally used in infusion pumps. It is not possible to compensate for this.

[Problem that the invention seeks to solve]

As is clear from the above, sufficient infusion management cannot be achieved with an open system that controls the infusion pump's driving mogu at a constant rotation speed, or with an infusion control system that feedback controls the number of infusions. death,
This is due to the fact that it does not have a weight feedback mechanism that feeds back this information.

Therefore, the purpose of the present invention is to abandon the concept of conventional infusion pumps and provide a completely new infusion system that incorporates a feedback mechanism that solves the problems caused by "sagging" and "dispersion" of infusion tubes all at once. It's about doing.

[Means to solve problems]

Therefore, the present inventors have made extensive studies and have arrived at the present invention. That is, in an infusion pump that drives an elastic infusion tube to feed liquid, the total weight of the drug solution container and the amount of drug solution is detected as a signal from a detector,
Compare and calculate the actual amount of liquid delivered based on the signal and the set amount of liquid delivered based on the set liquid delivery rate set on the infusion pump, and control the drive motor so that the actual amount of delivered liquid becomes the set amount of liquid delivered. This eliminates the problem of ``sagging'' of the infusion tube, makes the actual liquid delivery rate constant regardless of time, and ``variations'' between infusion tubes.It also absorbs the influence of the viscosity of the drug solution and eliminates any It has been found that even if an infusion tube is used, it is possible to infuse the actual amount of fluid in accordance with a pre-planned desired actual fluid delivery rate. Here, as the detector, any method such as a load cell or position, capacitance, detection, etc. is possible, but a load cell is preferable.

[For production]

According to the present invention, even when the actual liquid delivery speed decreases due to "sagging" of the infusion tube even though the rotation speed of the drive motor is constant, the rotation speed of the drive motor can be increased by an amount commensurate with the decrease. This may cause the infusion tube to become sagging.
It is possible to transfer liquid at a pre-planned set liquid transfer rate and amount.

As a result, Fig. 5C is obtained, and a constant actual liquid delivery rate is always ensured regardless of time, making it possible to realize highly accurate infusion management.

The "sag" of the infusion tube tends to increase especially after 24 hours, so it has become possible to handle long-term infusions of 24 hours or more. Also, “variation” between infusion tubes
By being unaffected by the viscosity of the chemical solution and the viscosity of the chemical solution, the versatility is greatly improved, and manufacturing costs can be reduced by reducing the accuracy control required for the assembly of the IFI liquid tube.

As described above, the significance and effects of the present invention, which enables highly accurate infusion management and long-term operation with the same infusion tube, expands the versatility of infusion tubes, and makes it possible to reduce the cost of infusion tubes, are significant. be. It is no exaggeration to say that the contribution it will make to future infusion management systems is immeasurable.

As is clear from the above explanation, one major effect is that the present invention improves the accuracy of the actual liquid feed amount due to temperature differences.

It goes without saying that the present invention can also be suitably applied to cases where the set liquid delivery rate of the infusion pump is driven by an arbitrary program with respect to time.

〔Example〕

Next, embodiments of the infusion pump according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows an embodiment of the present invention in which a finger pump is used as the infusion pump and a load cell is used as the detector.

The drug solution 16 placed in the drug solution container 14 is transferred to the infusion tube 1 at a set solution feeding rate set in advance by the solution feeding rate setting device 22.
The infusion pump unit 20 sends the liquid through the infusion pump 8 .

The set amount of liquid to be fed after a certain period of time is given by the reference voltage generator 24 as a voltage-hour relationship as shown in FIG. 2 (shown by on/off control). On the other hand, stand 10
Although the amount of the chemical solution in the chemical solution container 14 attached to the device decreases with time, the total weight of the drug solution container 14 and the amount of the drug solution at a certain time is obtained by the load cell 12 as a detection signal. Output r from reference voltage generator 24 and load cell 12
The output m from is compared by a window comparator 26,
Actual amount of liquid to be delivered of the chemical liquid 16 in the chemical liquid container 14 (output is sign inverted)
Is it larger than the set liquid flow rate?

Alternatively, depending on whether the signal is small, a low-speed signal or a high-speed signal is output. In response to this output signal, the motor driver 28 changes the speed of the infusion pump unit 20 based on the output signal, and is controlled so that the actual amount of liquid to be delivered becomes the set amount of liquid to be delivered. Motor driver 28
The control method depends on the purpose of use, conditions, etc.
Off control or proportional control is preferred.

FIG. 3 shows the relationship between the output of the reference voltage generator 24 in one hour and a program that changes the set liquid feeding rate at time T0.

FIG. 4 similarly shows the relationship between the output of the reference pressure generator 24 and the hour in the case of a program in which the set liquid feeding rate is changed at times T and T2.

It goes without saying that both the cases of FIGS. 3' and 4 can be suitably applied to the case of FIG.

The weight may be detected by an electrical, optical, or capacitive position detector instead of the load cell 12.

In the present invention, in the case of an infusion pump, the liquid delivery rate is usually set in terms of volume/time, but it may also be set in terms of weight/time.

〔Effect of the invention〕

As is clear from the above-mentioned embodiments, the infusion pump according to the present invention overcomes the drawbacks of conventional infusion pumps, such as a decrease in the actual liquid delivery rate due to the infusion tube becoming loose, and (
In some cases, there may be a slight increase), resulting in a decrease in accuracy, or a decrease in accuracy due to "variation" between infusion tubes.In addition, the influence of the viscosity of the drug solution is completely resolved, resulting in highly accurate infusion management, and even the same infusion tube. In addition, it has also made it possible to expand the versatility of infusion tubes and reduce the cost of infusion tubes. Therefore, the present invention is an extremely excellent invention that can be said to revolutionize future infusion systems.

In addition, the detection signal of the load cell in the present invention can also be used to notify when the drug solution in the drug solution container runs out, that is, to notify the completion of infusion, or to warn of excess or insufficient infusion.

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

[Brief explanation of drawings]

Fig. 1 is a system diagram showing an embodiment of the infusion pump according to the present invention, Fig. 2 is a characteristic diagram of the output of the actual liquid delivery amount according to the program with respect to time of the reference voltage generator, and Figs. Each time T. Or time T1. Reference voltage generator 2 in the case of a program that changes the set liquid feeding speed with T2
FIG. 5 is a characteristic diagram showing the relationship between the output of No. 4 and the hourly output, and FIG. 5 is a characteristic diagram showing the relationship between the actual liquid feeding speed (or actual liquid feeding amount) and time. 10. Stand 12. Load cell 14, drug solution container 16, drug solution 18, infusion tube 20, infusion pump section 22, solution feeding speed setting device 24, reference voltage generator 26, width comparator 28, motor l Helim FIer, 2

Claims (2)

[Claims] (1) In an infusion pump that drives an elastic infusion tube to deliver liquid, the total weight of the drug solution container and the amount of drug solution is detected as a signal from a detector, and the actual amount of delivered solution obtained from the detection signal is determined. An infusion pump, characterized in that the drive motor is controlled so that the actual amount of fluid delivered becomes the set amount of fluid delivered by comparing and calculating the set amount of fluid delivered based on the set fluid delivery rate set in the infusion pump. (2) The infusion pump according to claim (1), wherein the set liquid delivery rate of the infusion pump is configured by an arbitrary program with respect to time.