Liquid medicine administration device

A liquid medicine administration device is configured to reduce the load on the power supply at the start of use and includes: a drive mechanism that advances a plunger that pushes a liquid medicine from a liquid medicine container filled with the liquid medicine toward a distal end opening of the liquid medicine container; and a control unit that controls operation of the drive mechanism, in which the drive mechanism includes a motor that applies, to the plunger, a drive force for advancing the plunger, and an encoder that detects a rotation of the motor, and when driving the drive mechanism, the control unit starts the encoder after starting the motor.

FIELD OF THE INVENTION

The present invention relates to a liquid medicine administration device configured to reduce a load on a power supply at the start of use.

BACKGROUND DISCUSSION

In the related art, as disclosed in Japanese Patent Application Publication No. 2015-181869, there is known a syringe pump type liquid medicine administration device that administers a liquid medicine, filled in a liquid medicine container, to a living body. The syringe pump type liquid medicine administration device includes a power supply, a drive mechanism, and a control unit, and continuously administers the liquid medicine with high accuracy for a long time by moving a plunger little by little by the drive mechanism.

This type of liquid medicine administration device is refrigerated and stored until it is used by a user. Therefore, the liquid medicine administration device is devised to be extremely downsized so that a refrigerated storage space is small. For example, a power supply capacity is set to a minimum capacity capable of securing a capacity sufficient for normal administration of the liquid medicine after the refrigeration and storage in consideration of a decrease in the power supply capacity due to natural discharge during the refrigerated storage, and the power supply is configured by a button battery having a capacity sufficient to cover the set capacity.

SUMMARY

At the time of using the liquid medicine administration device, when a power switch is turned on, the control unit drives the drive mechanism simultaneously, and moves the plunger little by little to administer the liquid medicine to the living body. However, since a small button battery is adopted as the power supply, when a drive device is driven simultaneously, a load on the power supply increases, and a power supply voltage temporarily drops greatly. In the liquid medicine administration device, when the power supply voltage is smaller than a specified value, a safety device operates and all operations are stopped. Therefore, the administration of the liquid medicine is stopped.

The liquid medicine administration device disclosed here is configured to reduce a load on a power supply at the start of use.

The liquid medicine administration device including: a drive mechanism that advances a plunger that pushes a liquid medicine from a liquid medicine container filled with the liquid medicine toward a distal end opening of the liquid medicine container; and a control unit that controls operation of the drive mechanism, in which the drive mechanism includes a motor that applies, to the plunger, a drive force for advancing the plunger, and a rotation detection unit that detects a rotation of the motor, and when driving the drive mechanism, the control unit starts the rotation detection unit after starting the motor.

In the liquid medicine administration device, since the rotation detection unit is started after the motor is started, the load on the power supply at the start of use can be reduced.

In accordance with another aspect, a liquid medicine administration device comprises: a housing; a liquid medicine container that possesses a distal end, the liquid medicine container containing liquid medicine, with the distal end of the liquid medicine container including an opening through which the liquid medicine in the liquid medicine container is discharged during administration of the liquid medicine; an axially movable plunger connected to a gasket that is slidably positioned in the liquid medicine container so that axial movement of the plunger toward the distal end of the liquid medicine container results in axial movement of the gasket towards the liquid medicine of the liquid medicine container and discharge of the liquid medicine through the opening at the distal end of the liquid medicine container; a motor operatively connected to the plunger to axially move the plunger and the gasket toward the distal end of the liquid medicine container; and a rotation detector that detects rotation of the motor. A control unit is connected to the motor and to the rotation detector to control operation of the motor and the rotation detector, including starting operation of the motor and starting operation of the rotation detector. The control unit is configured to start operation of the rotation sensor after the operation of the motor has been started and after the motor has been operating.

According to another aspect, a method comprises inserting a needle tube into a living body, wherein the needle tube is connected to an opening at a distal end of a liquid medicine container containing liquid medicine, with a gasket positioned in the liquid medicine container and connected to a plunger so that axial movement of the plunger results in axial movement of the gasket. The plunger is operatively connected to a motor so that operation of the motor results in the axial movement of the plunger and the gasket, with the motor rotating during operation, and rotation of the motor being detected by a rotation detector. The method additionally involves starting operation of the motor, operating the motor so that the motor rotates and axially moves the plunger and the gasket toward the distal end of the liquid medicine container to discharge the liquid medicine through the opening at the distal end of the liquid medicine and is delivered to the needle tube so that the liquid medicine is administered to the living body, and starting operation of the rotation detector after the motor is operating.

DETAILED DESCRIPTION

Set forth below with reference to the accompanying drawings is a detailed description of embodiments of a liquid medicine administration system, a liquid medicine administration device and an administration tool representing examples of the inventive liquid medicine administration system, liquid medicine administration device and administration tool disclosed here. The following description does not limit the technical scope or meaning of terms in the claims. Furthermore, dimensional ratios in the drawings are exaggerated for convenience of description, and may be different from actual ratios.

FIGS.1to6illustrate a liquid medicine administration system10, a liquid medicine administration device100, and an administration tool200according to the present embodiment.FIG.1is a side view of a liquid medicine administration system.FIG.2is a view schematically illustrating a usage example of the liquid medicine administration system.FIG.3is a schematic perspective view of a liquid medicine administration device.FIG.4is a schematic perspective view of a chassis included in a housing and each component member assembled to the chassis.FIG.5is a plan view of the liquid medicine administration device illustrating a state before a plunger is moved forward.FIG.6is a plan view of the liquid medicine administration device illustrating a state after the plunger is moved forward. An arrow X in each drawing indicates a “longitudinal direction (longitudinal direction of a liquid medicine container110)” of the liquid medicine administration device100, an arrow Y indicates a “width direction (depth direction)” of the liquid medicine administration device100, and an arrow Z indicates a “height direction” of the liquid medicine administration device100.

Liquid Medicine Administration System

The liquid medicine administration system10is used to administer a liquid medicine into a living body. As illustrated inFIG.1, the liquid medicine administration system10includes the liquid medicine administration device100and the administration tool200.

As illustrated inFIG.2, the liquid medicine administration device100and the administration tool200are configured as a patch type used by being stuck on a body surface (skin) H of a user. A body part of the user to which the liquid medicine administration device100and the administration tool200are attached is not particularly limited, but is, for example, an abdomen or a femoral part.

For example, the liquid medicine administration system10can continuously administer a liquid medicine filled in the liquid medicine container110included in the liquid medicine administration device100into the living body for a relatively long time (for example, approximately several minutes to several hours) by a pressing action of a plunger130(seeFIG.4) to be described later. The liquid medicine administration system10may be configured to intermittently administer the liquid medicine into the living body.

Liquid Medicine Administration Device

As illustrated inFIGS.3to6, the liquid medicine administration device100includes the liquid medicine container110including a cylindrical (barrel-shaped) main body111filled with the liquid medicine, a housing120that holds the liquid medicine container110, the plunger130that pushes the liquid medicine in the liquid medicine container110, a drive mechanism140that advances (axially advances) the plunger130toward a distal end opening of the liquid medicine container110, a detection unit150that detects a portion134to be detected of the plunger130and detects completion of feeding of the liquid medicine based on a detection result, and a control unit160that controls operation of the drive mechanism.

As illustrated inFIGS.3and4, the housing120includes a box-shaped housing main body120ain which an accommodation space128is formed, and a chassis (corresponding to a “support portion”)127which is accommodated in the accommodation space128of the housing main body120aand can be fixed to the housing main body120a.

As illustrated inFIG.3, a window portion123athat allows the inside of the accommodation space128to be visually recognized from the outside of the housing120is formed on an upper surface123of the housing main body120a. The window portion123ais formed by providing a transparent or translucent portion in a part of the housing main body120a.

A proximal end opening125for inserting a chassis127into the accommodation space128of the housing main body120ais formed on a proximal end side in a longitudinal direction of the housing main body120a. The proximal end opening125of the housing main body120ais closed by a lid member in a state in which the chassis127is accommodated in the accommodation space128.

A bottom surface121of the housing main body120ais provided with a sheet-like sticking portion that can be stuck to the body surface H of the user. In an initial state before the liquid medicine administration device100is attached to the user, a peelable or removable protective sheet is attached to a sticking surface of the sticking portion.

As illustrated inFIG.4, the chassis127holds the liquid medicine container110, the plunger130, the drive mechanism140, the detection unit150, the control unit160, and a power supply unit170.

The liquid medicine container110is a so-called prefilled liquid medicine container. Therefore, the liquid medicine is filled in a lumen111aof the main body111of the liquid medicine container110in advance. Examples of the liquid medicine include protein preparations, narcotic analgesics, diuretics, and the like.

A sealing member for preventing leakage of the liquid medicine is disposed in the distal end opening (discharge port) formed at a distal end112of the liquid medicine container110. As illustrated inFIG.3, the distal end opening of the liquid medicine container110is disposed so as to protrude outward from the housing main body120a. Furthermore, an attachment portion115that is connected to a tube240(seeFIG.1) to be described later is attached to a distal end portion of the liquid medicine container110, the distal end portion protruding from the housing main body120a.

A main body131of the plunger130is inserted into or positioned in the lumen111aof the main body111of the liquid medicine container110(seeFIGS.4and5). A gasket135slidable on an inner wall of the liquid medicine container110is disposed at a distal end of the main body131of the plunger130. The gasket135liquid-tightly seals a proximal end side of the gasket135by liquid-tightly bringing an outer circumferential portion of the gasket135into close contact with an inner circumferential surface of the main body111of the liquid medicine container110.

In the present embodiment, the gasket135is configured to be shrinkable in a direction (longitudinal direction) in which the plunger130advances when the plunger130advances in a state in which the gasket135abuts against a distal end inner wall112a(seeFIG.5) of the liquid medicine container110. The gasket135can be made of, for example, a flexible resin material such as a rubber material or an elastomer so as to be shrinkable as described above.

As illustrated inFIG.5, the gasket135has a tapered shape in which an outer diameter decreases toward a distal end side. Furthermore, the shape of the gasket135is substantially the same as the shape of the distal end inner wall112aof the liquid medicine container110.

As illustrated inFIG.5, the portion134to be detected is provided at a proximal end of the plunger130. The portion134to be detected is used to detect completion of feeding of the liquid medicine by the liquid medicine administration device100.

The control unit160controls a liquid medicine feeding operation of the liquid medicine administration device100. The control unit160can be configured by, for example, a known microcomputer (electronic circuit element) on which a CPU, a RAM, a ROM, and the like are mounted. The control unit160integrally controls operations of the drive mechanism140, the detection unit150, and the power supply unit170.

As illustrated inFIG.5, the detection unit150is disposed in the chassis127. As illustrated inFIG.6, the detection unit150detects completion of feeding of the liquid medicine of the liquid medicine administration device100when the portion134to be detected included in the plunger130comes into contact with the detection unit150. The detection unit150can be configured by, for example, a known contact-type sensor that transmits a predetermined electric signal when the portion134to be detected comes into contact with the detection unit150. The control unit160acquires information regarding completion of feeding of the liquid medicine by receiving the electric signal from the detection unit150. When the plunger130advances by a predetermined amount, the specific configuration and the like of the detection unit150are not particularly limited as long as a position of the portion134to be detected of the plunger130can be detected.

The power supply unit170can be configured by, for example, a known button battery or the like. The liquid medicine administration device100is required to be downsized. Therefore, a small button battery is used as the power supply unit170.

As illustrated inFIG.4, the drive mechanism140includes a motor141that receives a drive current from the power supply unit170and applies a drive force, a speed reduction mechanism143that includes a gear or the like transmitting the drive force of the motor141, an encoder146that is provided adjacent to the speed reduction mechanism143and includes a photointerrupter as a rotation detection unit that detects rotation of the motor141and a slit plate that rotates in accordance with the rotation of the motor141, and a feed screw147that is connected to the speed reduction mechanism143.

The feed screw147is connected to a proximal end connection portion133disposed in the vicinity of the proximal end of the plunger130. The feed screw147converts a rotational motion transmitted from the speed reduction mechanism143into a linear motion to advance the plunger130in the longitudinal direction (X direction). The plunger130advances toward a distal end side of the liquid medicine container110to push the liquid medicine from the lumen111aof the main body111of the liquid medicine container110to the tube240(seeFIG.1).

Administration Tool

As illustrated inFIGS.1and2, the administration tool200is configured to be connectable to the liquid medicine administration device100.

The administration tool200includes a connector210, a needle tube220that punctures the living body, a puncture unit (cannula housing)230, the tube240, and a puncture assisting tool250that assists in puncturing the living body with the needle tube220.

The connector210is configured to be connectable to the liquid medicine administration device100via an attachment portion215fixed to the connector210. The attachment portion215can be connected to the liquid medicine administration device100by being externally fitted to the attachment portion115(seeFIG.4) provided in the vicinity of the distal end112of the liquid medicine container110protruding to the outside of the housing120.

Inside the attachment portion215, a connection needle portion through which the sealing member disposed at a distal end portion of the liquid medicine container110can be inserted is disposed. The tube240communicates with the lumen111aof the main body111of the liquid medicine container110via the connection needle portion.

Inside the puncture unit230, a flow path through which the tube240communicates with a lumen of the needle tube220is formed. The liquid medicine fed to the puncture unit230through the tube240is administered into the living body through the flow path formed inside the puncture unit230and the needle tube220.

When the liquid medicine is fed to the user, the puncture assisting tool250is attached to the puncture unit230. The puncture assisting tool250holds an introduction needle (inner needle)251. The introduction needle251protrudes from a distal end of the needle tube220in a state in which the puncture assisting tool250is attached to the puncture unit230. By puncturing the living body with the needle tube220in a state in which the introduction needle251is inserted into the needle tube220, the user can insert the needle tube220into the living body while preventing the needle tube220from being broken or the like.

The puncture assisting tool250is removed from the puncture unit230after puncturing the living body with the needle tube220. When the puncture assisting tool250is removed from the puncture unit230, the introduction needle251is removed from the lumen of the needle tube220.

After puncturing the living body with the needle tube220, the puncture assisting tool250is removed, and the puncture unit230is left on the body surface H of the user in a state in which the needle tube220is indwelled in the living body. When the plunger130of the liquid medicine administration device100advances in the liquid medicine container110in this state, the liquid medicine filled in the liquid medicine container110is fed to the lumen of the needle tube220via the tube240and the flow path of the puncture unit230.

The introduction needle251can be formed of, for example, a metal needle. Furthermore, the needle tube220can be formed of, for example, a resin tubular member (cannula).

Similarly to the liquid medicine administration device100, the administration tool200is configured as a patch type used by being stuck on the body surface H of the user. A sheet-like sticking portion that can be stuck to the body surface H is provided on a contact surface (bottom surface)231of the puncture unit230of the administration tool200. In an initial state before the administration tool200is attached to the user, a peelable protective sheet is attached to a sticking surface of the sticking portion.

As described above, a schematic configuration of the liquid medicine administration system10, the liquid medicine administration device100, and the administration tool200has been described. The liquid medicine administration device100is required to be reduced in size and cost in order to facilitate handling at the time of use and to save a storage space at the time of storage. Therefore, a small button battery is adopted as the power supply unit170. Since there is a limit to supplying large electric power instantaneously, the button battery cannot apply a large load at a time. Therefore, the control unit160controls the drive mechanism140as follows.

Next, a specific operation of the control unit160will be described with reference toFIGS.7A to11.FIG.7Ais a block diagram of a control system of the liquid medicine administration device100.FIG.7Bis a diagram schematically illustrating a configuration of the encoder ofFIG.7A.FIG.8is a graph illustrating temporal changes in an output current and a power supply voltage of the control unit160at the start of use.FIG.9is an operation flowchart of the control unit160.FIG.10is a diagram illustrating a temporal change in a power supply voltage of the related art at the start of using the liquid medicine administration device100.FIG.11is a diagram illustrating a temporal change in a power supply voltage of the present application at the start of using the liquid medicine administration device100.

As illustrated inFIG.7A, the control unit160is electrically connected to the motor141. A rotation shaft of the motor141is mechanically connected to the encoder146as the rotation detection unit and the speed reduction mechanism143. As also illustrated inFIG.7B, the encoder146includes a photointerrupter144including an optical sensor and a slit plate145in which a large number of slits are radially formed, and detects the rotation of the motor141by detecting whether or not light passes through the slits of the slit plate145with the optical sensor of the photointerrupter144. As illustrated inFIG.7A, the photointerrupter144is electrically connected to the control unit160. The present embodiment describes that the encoder146may use the photointerrupter144as the rotation detection unit, but this is one example and an encoder using a magnetic sensor may alternatively be used.

When the control unit160rotates the motor141, the speed reduction mechanism143is driven, and the plunger130advances in the liquid medicine container110(seeFIGS.5and6). The encoder146provided adjacent to the speed reduction mechanism143detects the rotation of the motor (e.g., rotation of the motor output)141, and the control unit160calculates a rotation speed of the motor141based on the rotation of the motor141detected by the encoder146. The rotation of the motor141detected by the encoder146is fed back to the control unit160, and the control unit160calculates the rotation speed of the motor141in accordance with the feedback and determines whether or not the motor141is rotating. The rotation detection unit can also be incorporated as a part of the speed reduction mechanism143. Specifically, the slit plate145is omitted, and instead of this, a large number of slits are radially provided in the gear of the speed reduction mechanism143, and the rotation of the motor141is detected by detecting whether or not light passes through the slits provided in the gear by using the optical sensor of the photointerrupter. In this case, the encoder includes the gear of the speed reduction mechanism143and the photointerrupter.

At the start of using the liquid medicine administration device100, as illustrated in an upper graph ofFIG.8, a momentarily excessively large current (starting current that forms a peak current) flows, after that, the current decreases to a steady state current in response to the magnitude of the load, and is stabilized. As illustrated in a lower graph ofFIG.8, a voltage of the button battery which is the power supply unit170decreases momentarily excessively in response to the magnitude of the flowing current, and then the decrease in the voltage is stabilized. When the voltage of the button battery is too low, all the operations of the liquid medicine administration device100are stopped, and the administration of the medicine is interrupted.

Therefore, as illustrated in an operation flowchart ofFIG.9, the control unit160first drives the motor141(S100), and when the current of the motor141decreases to a steady state current in response to the load (S101), starts the photointerrupter144(S102).

That is, at the start of using the liquid medicine administration device100, the control unit160first drives the motor141, and starts the photointerrupter144after the current of the motor141is stabilized, so that the starting currents of the motor141and the photointerrupter144are not supplied from the power supply unit170at a time (at the same initial time). Thus, the start of the operation of the photointerrupter144is delayed relative to the start of operation of the motor141so that the motor141operates for a period of time before operation of the photointerrupter144is started.

In the related art (known art), since the motor141and the photointerrupter144are started at the same timing at the start of using the liquid medicine administration device100, as illustrated inFIG.10, the power supply voltage drops greatly and so the safety device of the liquid medicine administration device100is readily operated. However, as in the present application, when the photointerrupter144is started after the motor141is started, as illustrated inFIG.11, the voltage temporarily drops twice, but the power supply voltage does not drop greatly (i.e., does not drop so significantly) as in the related art, and so the safety device is difficult to be operated (i.e., is not so likely to be operated). That is, the administration of the liquid medicine is not interrupted.

Therefore, the load on the power supply unit170at the start of using the liquid medicine administration device100can be reduced. According to this, a battery constituting the power supply unit170can last longer than the related art. Furthermore, even in a case where the voltage of the battery decreases or internal resistance of the battery increases, the operation range of the battery can be expanded. Furthermore, since electric capacity of the power supply unit170can be reduced, miniaturization and cost reduction of the liquid medicine administration device100can be achieved.

The detailed description above describes embodiments of a liquid medicine administration device and operational method representing examples of the inventive liquid medicine administration device and operational method disclosed here. The invention is not limited, however, to the precise embodiments and variations described. Various changes, modifications and equivalents can be effected by one skilled in the art without departing from the spirit and scope of the invention as defined in the accompanying claims. It is expressly intended that all such changes, modifications and equivalents which fall within the scope of the claims are embraced by the claims.