JPH0567306B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a method for keeping the number of drops of medicine supplied to a patient from an infusion tube following a medicine bottle to a patient through a tube constant by controlling an infusion pump. This invention relates to an adjustable drip device.

[Conventional technology]

This type of device uses an open-loop method in which the number of drops that matches the characteristics of the tube is set in advance and the pump drive motor is controlled in an open loop using the set signal, and the other is a method that detects the number of drops based on the drip signal from the drip sensor. There is a closed-loop method in which the number of drips or the interval between drips is compared with a target value, and the motor is feedback-controlled using the error signal.

[Problem to be solved by the invention]

However, with the former method, highly accurate control that follows variations in tube characteristics or changes over time is not possible.

On the other hand, in the latter method, although this drawback is resolved, the feedback signal becomes unstable in the initial state of operation after power is turned on, and in some cases, an excessive amount of fluid may be infused. This is particularly a problem when the drug is a cardiotonic agent, an antiarrhythmic agent, or the like, which requires highly accurate flow control. Furthermore, since the drip sensor is usually attached to a translucent drip tube suspended indoors, it may be affected by external noise, or may generate false drip signals that do not correspond to regular drips from the pulsed received signal. There is a possibility that an erroneous feedback signal may be generated due to an error in detection or detection of a drop, resulting in abnormal flow rate control.

Therefore, an object of the present invention is to provide an infusion device that can always stably infuse a fluid at a flow rate suitable for an infusion tube immediately after the start of infusion.

[Means to solve the problem]

As shown in FIG. 1, in the present invention, a medicine is supplied to a patient through a tube 1 from an infusion tube 2 that follows a medicine bottle, and the flow rate is controlled by a motor 3a of an infusion pump 3 attached to the tube 1. In order to achieve the above object in an infusion device that is now controlled in response to a motor control signal,
By being attached to the drip tube 2, a storage means 4 for storing a standard drip interval suitable for the tube 1, and an open loop motor control signal generating means 5 for generating a motor control signal corresponding to the standard drip interval. A drip sensor 6 that detects dripping and outputs a drip signal; and a drip interval detector that detects, for feedback, the actual drip interval, which is limited to not exceed a predetermined deviation from the reference drip interval based on the drip signal. means 7, and a closed-loop motor control signal generator for generating a motor control signal corresponding to the error between the infusion interval detected by the infusion interval detection means 7 and the reference infusion interval, instead of the motor control signal, after the initial stage of infusion. means 8.

[Effect]

At the start of infusion, the open loop motor control signal generating means 5 generates a motor control signal to control the motor 3a so that the number of infusions is suitable for the tube 1 according to the reference infusion interval in the storage means 4.

During this time, the drip interval detection means 7 detects the drip sensor 6.
The actual infusion interval is detected based on the infusion signal output from the infusion signal. Then, after reaching a predetermined number of drops or after a certain period of time has elapsed, in response to the operation initial signal, the closed-loop motor control signal generating means 8 converts the reference drip interval and the detected drip signal. A motor control signal corresponding to the error is generated, and the motor 3a is thereafter subjected to feedback control. If the detected drip interval exceeds or falls below a predetermined deviation amount from the standard drip interval, the drip interval detection means 7 limits the drip interval, and the motor control signal generating means 8 compares the upper limit or lower value with the standard drip interval. generates a motor control signal corresponding to the error.

〔Example〕

FIG. 2 shows an infusion device according to an embodiment of the present invention, which is configured so that a plurality of types of tubes can be selectively used.

In the figure, reference numeral 10 denotes an infusion tube that is connected through a tube 11 to a medicinal liquid bottle filled with a medicinal liquid;
A tube 11 for supplying a medical solution to the patient is further connected. A light emitting element 1 is mounted on the outer wall of this drip tube.
2. A drip sensor composed of opposing light receiving elements 13 and a signal processing circuit is attached. A peristaltic type infusion pump 20 is attached to the tube 11. This pump is tube 1
A tube drive mechanism 21, which is well known per se, performs infusion by squeezing the tube downward, a motor 22 that drives and controls this drive mechanism, and drives the motor 22 in response to an input open or closed loop motor control signal. It is composed of a motor drive circuit 23.

Reference numeral 30 denotes a CPU equipped with an I/O port 31, ROM 32, etc., and constitutes a microcomputer that functions as the aforementioned storage means, open and closed loop motor control signal generation means, and drip interval detection means. The ROM 32 contains programs necessary for operation as well as five types of tubes 11 that can guarantee stable pump operation for various inner diameter tubes 11 that may be used, classified into five stages, for example, between 2.0 mm and 3.0 mm. It stores five types of upper and lower limit values corresponding to the reference infusion interval and its ±10% deviation amount.

Then, the CPU 30 generates an open-loop motor control signal corresponding to the reference infusion interval read from the ROM 32 according to the setting of the tube setting switch 18, and in order to set the initial operation, the infusion signal is changed to 8 times from the start of infusion. Count. Further, the drip interval is sequentially calculated from the drip signal, and when the count reaches 8, the error between the reference drip interval and the detected actual drip interval is calculated. Further, if the infusion interval is above or below the above-mentioned upper and lower limits, the detected infusion interval is limited to these limit values. The permissible range for the feedback signal defined by this ±10% value is to avoid abnormal flow control due to false drip signals or detection errors, and to avoid variations in tube inner diameter, thickness, etc., or changes in tube characteristics over time. is set so that it can be followed sufficiently.

The operation of the infusion device configured in this way is as follows:
The explanation will be based on the flowchart shown in the figure.

When using the infusion device, the tube setting switch 18 is used to set the tube to be used. Immediately after the start of the infusion, the CPU 30 counts the infusion signals supplied from the infusion sensor and detects the actual infusion interval as a feedback signal. Then, the set reference drip interval is read from the ROM 32, and the corresponding open loop motor control signals are generated and supplied to the motor drive circuit 23 until eight drip signals are detected.

Thereby, the infusion pump 20 performs infusion at a flow rate suitable for the selected tube 11 in an open loop. When eight infusion signals are detected, feedback control corresponding to the error between the stabilized actual infusion interval and the reference infusion interval that occurred during this period is started, and from then on, the detected infusion interval matches the reference infusion interval. Closed-loop control is performed to ensure that During this time, even if an abnormality occurs in the infusion signal,
The feedback drip interval is limited to within ±10% deviation of the reference drip interval to prevent erroneous and abnormal flow control.

In the above-mentioned embodiment, it is assumed that a plurality of types of tubes are selectively used. However, the tube selection switch 18 is not provided, and only one reference interval value is stored in memory or as a dedicated device for a specific tube. It is also conceivable to implement it as a device in which voltage levels and the like are stored. Further, although the initial period of operation is defined by the number of drops, it can also be defined by a predetermined time using a timer.

〔Effect of the invention〕

As described above, according to the present invention, since open-loop control is performed based on the preset reference infusion interval unique to the tube at the beginning of the infusion, the infusion is not affected by the feedback signal that may become unstable. This eliminates the possibility that too much or too little medicine will be supplied immediately after the start. Thereafter, feedback control is similarly performed based on the error in the actual drip interval with respect to this reference drip interval, and highly accurate flow rate control is performed regardless of variations in tube characteristics. Furthermore, during this closed-loop control period, by limiting the level of the feedback signal, excessive or insufficient drug supply due to an abnormality in drip detection is prevented. Therefore, an infusion device is realized that enables infusion at an appropriate and stable flow rate immediately after the start of infusion.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of drip monitoring according to the present invention, FIG. 2 is a diagram showing the configuration of an infusion device according to an embodiment of the present invention, and FIG. 3 is a flowchart explaining the operation of the same embodiment. . 1, 11... tube, 3, 20... infusion pump, 3a, 22... motor, 6... drip sensor,
10...Drip tube.

Claims (1)

[Scope of Claims] 1. The medicine is supplied to the patient through the tube from the drip tube that follows the medicine liquid bottle, and the flow rate is as follows:
In an infusion device that is controlled by a motor-driven infusion pump attached to a tube in response to a motor control signal, the infusion device includes a storage means for storing a reference infusion interval that is compatible with the tube, and the reference infusion interval. an open-loop motor control signal generating means that generates a motor control signal corresponding to the infusion; a drip sensor that is attached to the drip tube to detect dripping and output a drip signal; Infusion interval detection means for detecting the actual infusion interval, which is limited to not exceed a predetermined deviation amount from the interval, for fieldback; An infusion device comprising: closed-loop motor control signal generation means for generating a motor control signal corresponding to an error between the reference infusion interval and the infusion interval detected by the means.