Patent Application
20190388610
The present disclosure relates to a spring powered ambulatory infusion apparatus.
In general, there are three types of ambulatory infusion pumps, elastomeric bladder type pumps, pneumatic pumps and spring powered pumps. The elastomeric bladder pump is relatively small and light-weighted. However, it is difficult for this type of infusion pump to provide a uniform flow rate. On the other hand, the spring powered pump is more advantageous for providing a generally linear flow rate. However, the size of the spring powered pump is generally bigger than the elastomeric bladder type pump. The foregoing discussion in this section is to provide general background information, and does not constitute an admission of prior art.
One aspect of the invention provide a spring actuated infusion pump, which may comprise: a syringe module configured to contain infusion medicine, wherein the syringe module comprises a syringe barrel and a piston, wherein the syringe barrel comprises a bottom and side walls extending from the bottom in a direction, wherein the syringe barrel further comprises an outlet for discharging infusion medicine, wherein the piston is disposed in the syringe barrel and movable in the direction, wherein the piston is configured to push infusion medicine contained in the syringe barrel toward the outlet; and an actuator module configured to engage with the syringe module, wherein the actuator module is further configured to push the piston in the direction, wherein the actuator module comprises a housing, two or more spring guide channels arranged side by side in the housing and two or more compression springs, each of which is retained in the corresponding spring guide channel, wherein each spring guide channel comprises an first end, a second end and a rounded portion between the first end and the second end, wherein each spring is compressible and configured to expand between a compressed state and an expanded state, wherein each spring comprises a fixed end, a movable end and a bent portion in conformation with the rounded portion of the corresponding guide channel, wherein the actuator comprises spring supports, each of which configured to block the second end of the corresponding spring guide channel such that the fixed end contacts and is stopped by the corresponding support, wherein the movable end is configured to move in the direction and further configured to push the piston when the spring expands, which causes the piston to move in the direction, wherein each spring guide channel is configured to retain the corresponding spring therein such that the fixed end, the movable end and the rounded portion of the corresponding spring overlap the piston in the compressed state and the expanded state when viewed in the direction while the fixed end and the movable end are located at opposite sides of the infusion apparatus, wherein the movable end of a first one of the springs and the movable end of a second one of the springs are located at opposite sides of the infusion apparatus when viewed in the direction.
In the foregoing apparatus, the entire portion of each spring overlaps the piston when viewed in the direction. The piston may have a generally rectangular shape when viewed in the direction, wherein the movable end of the first spring is configured to push the piston at a first corner of the piston, and the movable end of the second spring is configured to push the piston at a second corner of the piston that is diagonally opposite to the first corner. Each spring may have a U-shape in the compressed state, and each spring has a J-shape in the expanded state and while the movable end moves in the direction.
Still in the foregoing apparatus, the movable end of each spring may be located in the housing of the actuator module in the compressed state and located in the syringe barrel in the expanded state while the fixed end is located in the housing of the actuator in both the compressed state and the expanded state. Both the movable end and the fixed end of each spring may face the piston in the compressed state and in the expanded state. The bent portion of each spring in the compressed state may be partly deformed to extend linearly in the expanded state. Each spring may be formed of a single wire that is coiled and interconnects the fixed end and the movable end.
Yet in the foregoing apparatus, each channel may further include a first straight extension connected to the first end and a second straight extension connected to the second end, and the rounded portion of each channel interconnects the first and second straight extensions. The rounded portion may be semi-circular or arcuate. The actuator module may further comprise a locking mechanism configured to maintain the springs in the compressed state. In the expanded state of the spring, the piston may contact the bottom of the syringe barrel.
Further in the foregoing apparatus, the infusion apparatus may further comprise a pressure plate that contacts the movable end of each spring and is coupled to the piston to push the piston when the springs expand. The actuator module may further comprise two or more buckling-prevention guides extending from the pressure plate, wherein the movable end of each spring is inserted in the corresponding buckling-prevention guide that has a bending stiffness greater than that of the corresponding spring. Each buckling-prevention guide may comprise an end portion that is deformable and configured to deform in conformation with the rounded portion of the corresponding spring guide channel when the buckling-prevention guide is inserted in the corresponding guide channel. The actuator module may further comprise two or more posts extending from the pressure plate, wherein each post is inserted in the movable end of the corresponding spring, and each post has a bending stiffness greater than that of the corresponding spring. Each buckling-prevention guide may comprise telescopic pipes that receive the movable end of the spring, wherein each of the telescopic pipes is movable with respect to the rest of the telescopic pipes when the spring moves the piston in the direction.
Another aspect of the invention provide a method of infusing medicine to a patient, wherein the method may comprise: providing a syringe module containing infusion medicine therein, wherein the syringe module comprises a syringe barrel and a piston, wherein the syringe barrel comprises a bottom and side walls extending from the bottom in a direction, wherein the syringe barrel further comprises an outlet for discharging the medicine, wherein the piston is disposed in the syringe barrel and movable in the direction, wherein the piston is configured to push infusion medicine contained in the syringe barrel toward the outlet; providing an actuator module configured to push the piston in the direction when the actuator is engaged with the syringe module, wherein the actuator module comprises a housing, two or more spring guide channels arranged side by side in the housing and two or more compression springs, each of which is retained by the corresponding spring guide channel, wherein each spring guide channel comprises a first end, a second end and a rounded portion between the first end and the second end, wherein each spring is compressible and configured to expand between a compressed state and an expanded state, wherein each spring comprises a fixed end, a movable end and a bent portion in conformation with the rounded portion of the corresponding guide channel, wherein the actuator comprises spring supports, each of which configured to block the second end of the corresponding spring guide channel such that the fixed end contacts and is stopped by the corresponding spring support, wherein the movable end is configured to move in the direction and further configured to push the piston when the spring expands, which causes the piston to move in the direction; engaging the syringe module with the actuator module to form an infusion apparatus, wherein, in an engaged state of the syringe and the actuator module, each spring guide channel is configured to retain the corresponding spring such that the fixed end, the movable end and the rounded portion of the corresponding spring overlap the piston in the compressed state and the expanded state when viewed in the direction while the fixed end and the movable end are located at opposite sides of the infusion apparatus, wherein the movable end of a first one of the springs and the movable end of a second one of the springs are located at opposite sides of the infusion apparatus when viewed in the direction, wherein the springs are held in the compressed state; releasing the springs of the actuator module from the compressed state such that the springs expand and the movable ends of the springs push the piston, which causes the piston to move in the direction for discharging the infusion medicine through the outlet; upon completion of infusion, detaching the syringe module from the actuator module; and retracting the springs to the compressed state.
The foregoing method may further comprise engaging another syringe module containing infusion medicine with the actuator module for infusion in which the springs are held in the compressed state, and releasing the springs from the compresses state for infusion. In the foregoing method, each spring may have a U-shape in the compressed state before engaging, each spring becomes a J-shape after releasing and each spring becomes back to a U-shape after retracting.
Embodiments are described with reference to the accompanying drawings below. The terminology used in the description presented herein is not intended to be interpreted in any limited or restrictive manner, simply because it is being utilized in conjunction with a detailed description of certain specific embodiments of the invention.
In embodiments, a spring powered infusion apparatus includes a syringe module and an actuator module. The syringe module includes a syringe barrel and a piston that is inserted and movable in the syringe barrel. The actuator module is attached to one end of the syringe module. The infusion apparatus has a height smaller than that of typical spring powered infusion pumps. In embodiments, the infusion apparatus has a generally rectangular sectional shape that has a width and a thickness as shown in
The actuator module includes compression springs to push the piston for discharging medicine fluid contained in the syringe barrel when the compression springs expand. Generally, it is advantageous to use a spring that has a less force decrease rate, a smaller spring constant, and a smaller ratio of compression displacement versus free length. Relatively long compression springs may provide the above characteristics. However, the longer the spring is, the bigger the size of the infusion apparatus (in particular, the height of the apparatus) is. The infusion apparatus according to embodiments of the present invention provides improved spring configuration for reducing the height of the apparatus while providing an accurate flow rate or a uniform flow rate.
In embodiments, the actuator module uses multiple compression springs (e.g., two springs) that are relatively long to provide an accurate flow rate. To reduce the height of the apparatus, however, each compression spring of the actuator module is bent to have a U-shape or J-shape.
Further, in the actuator module, two compression springs are not only bent but also arranged side by side such that the two springs can fit through or be accommodated in the rectangular sectional shape of the infusion apparatus having the width and the thickness. Thus, the spring powered infusion apparatus according to embodiments has a reduced size while not compromising advantages of providing accurate flow rates.
Referring to
In embodiments, the syringe barrel 210 may be made of a transparent or translucent plastic material for showing the infusion fluid. The syringe barrel 210 may include scale markings on its wall for measuring the amount of the infusion fluid contained therein. The syringe barrel 210 includes a nozzle 212. A flexible infusion tube may be connected to the nozzle 212.
In embodiments, the syringe barrel 210 has a generally rectangular sectional shape with four rounded corners, as shown in
The piston 250 includes a piston body 252 and seals 254 covering the piston body 252. The seals 254 contact the sidewalls of the syringe barrel 210 for sealing between the piston and the sidewalls.
Referring to
The housing 302 includes a front member 304 and a rear member 306 that are coupled to each other and define a space for accommodating the tubes 310 and 312. Further, to provide secure engagement of the actuator module 300 and the syringe module 200, the housing 302 has a coupling structure that can engage with a counterpart coupling structure of the syringe barrel 210. The secure engagement is maintained during infusion of the infusion fluid.
The U-shape spring guide tubes 310 and 312 are arranged side by side in the housing 302 and fixed to the housing 302. Each of the guide tubes 310 and 312 includes a first end 314 and a second end 316 and a rounded channel portion 318 that interconnects the first end 314 and the second end 316. Each of the spring guide tubes 310 and 312 further includes a linear channel portion between the first end 314 and the rounded channel portion 318, and another linear channel portion between the second end 316 and the rounded channel portion 318.
In embodiments, the housing 302 includes outer walls, inner walls and bottom walls 307 and 308. The outer walls, inner walls and bottom walls define a space for receiving the tubes 310 and 312. In one embodiment illustrated in
Referring to
Each of the compression springs 320 and 322 are inserted in the corresponding one of the guide tubes 310 and 312. In the guide tubes 310 and 312, the springs 320 and 322 are bent to have a U-shape or J-shape. In embodiments, the springs 320 and 322 are at least partly accommodated in the tube 310 and 312. In one embodiment, substantially the entire portion of each of the springs 320 and 322 is accommodated in the corresponding tube in the fully compressed state. When each of the springs 320 and 322 expands, one end of each spring moves out of the corresponding tube and pushes the pressure plate 320 for infusion.
In one embodiment shown in
As shown in
In the illustrated embodiment, when the spring 320 is received in the tube 310, the fixed end 324 is locate at the right side of the actuator module 300, and the movable end 326 of the spring 320 is located at the left side of the actuator module 300. When the spring 322 is received in the tube 312, the fixed end 324 of the spring 322 is locate at the left side of the actuator module 300 and the movable end 326 of the spring 322 is located at the right side of the actuator module 300.
In embodiments, each of the spring 320 and 322 is bent in the corresponding guide tube 310 or 312 such that each spring includes a bent portion between two ends 324 and 326. In the embodiment illustrated in
In one embodiment shown in
The bent spring 320 has a width that is a dimension between the movable end and the fixed end measured in a width direction of the infusion apparatus and a thickness that is a dimension measured in a thickness direction of the infusion apparatus. In embodiments, the width of the spring 320 is smaller than that of the syringe barrel, and the thickness of the spring 320 is smaller than a half the thickness of syringe barrel. The bent spring 322 has dimensions substantially the same as those of the spring 320.
In embodiments, the bent springs 320 and 322 have a dimension in the width direction smaller than the width of the syringe barrel. In one embodiment, the bent springs 320 and 322 can be arranged side by side and located closely to each other such that both the bent springs 320 and 322 can be accommodated or fit through the rectangular sectional shape of the actuator when viewed from the top of the actuator along the center axis. In another embodiment, in a top view, both the springs 320 and 322 can be accommodated or fit through a rectangular sectional shape of the piston. Thus, the entire portion of the springs 320 and 322 can overlap the piston 250 in a viewing direction along the center axis. But, the invention is not limited thereto. In another embodiment, if it is allowed for the actuator module to have a size bigger than that of the syringe barrel, the spring may have a portion that does not overlap the piston in a top view.
When expanding, a portion of each of the springs 320 and 322 comes out of the corresponding one of the guide tubes 310 and 312 and moves along the center axis in the syringe barrel 210. This portion of each spring may be subject to buckling during expansion. Thus, the actuator module 300 further includes structures for preventing the springs 320 and 322 from buckling.
In embodiments, the actuator module 300 includes two buckling-prevention guides 342 and 343. In one embodiment, the guide 342 and 343 are fixed to the pressure plate 340. Each of the guides 342 or 343 extends upwardly from the pressure plate 340 for receiving the movable end 326 of the corresponding spring 320 or 322. Each guide 342 or 343 includes a rigid pipe portion 344 and a bendable portion 346 extending from the rigid portion 344. The bendable spring portion 346 can be bent in conformation with the rounded or curved portion of the corresponding tube 310 or 312 as shown in
In one embodiment, the buckling-prevention guide has a length the same as or slightly greater than a distance between the pressure plate 340 and the first end of the tube 310 or 312. The distance is measured when the pressure plate 340 is located at its lowest position. In this embodiment, a distal end portion of the buckling-prevention guide is located in and supported by the corresponding guide tube. This configuration provides more effective buckling-prevention function as the proximal end is fixed to the pressure plate 340 and the distal end is restricted by the corresponding guide tube. However, the invention is not limited thereto. In another embodiment, the length of the buckling-prevention guide may be slightly smaller than the distance between the pressure plate 340 and the first end of the tube.
Each buckling-prevention guide 342 or 343 has an inner diameter slightly greater than an outer diameter of the spring 320 or 322, and the buckling-prevention guide 342 or 343 has an outer diameter slightly smaller than an inner diameter of the tube 310 or 312. Thus, the tubes 310 and 312 can receive the guides 342 and 343, respectively, and the springs 320 and 322 can be at least partly retained in the guides 342 and 343, respectively. In the illustrated embodiment, each tube includes a portion having an enlarged inner diameter for receiving the corresponding buckling-prevention guide.
In another embodiment, the buckling-prevention structure is a pole 348 that extends from the pressure plate and is inserted in the spring as shown in
In one embodiment illustrated in
Each of the telescopic pipe structures 1342 and 1343 includes an inner pipe 1344 and an outer pipe 1346 receiving the inner pipe 1344. In one embodiment illustrated in
The springs 320 and 322 in the actuator module 300 tend to expand when there is no restriction. Thus, the actuator module 300 includes a locking mechanism for maintaining the compressed state of the springs 320 and 322. The locking mechanism includes a locking knob 352 coupled to the housing 310 and a locking post 354 attached to the pressure plate 340 and capable of engaging with the locking knob 352. The locking knob 352 can rotate about a knob axis perpendicular to the center axis. The knob 352 includes a cylindrical body 356 that includes protrusions 358 diametrically arranged on outer surface of the body 356. The locking post 354 includes a recess 360 for receiving the cylindrical body 356 and mating protrusions 362 formed on opposing surfaces of the recess 360. The protrusions 358 of the knob and the protrusions 362 of the locking post 354 can engage with each other by snap-fitting.
Referring to
In embodiments, when rotating the knob 352, the engagement of the knob 352 and the locking post 354 is released, and then, by the force of the springs 320 and 322, the piston 250 and the pressure plate 330 start moving. As shown in
When the springs 320 and 322 expand, at least a portion of each spring that is bent and located in the tube comes out of the corresponding tube and extends linearly. Therefore, the compression springs 320 and 322 are transformed from the U-shape to a J-shape during expansion. Further, the compression springs 320 and 322 push linearly the pressure plate 340 at the opposite sides of the piston 250, respectively, as the movable ends 326 of the springs 320 and 322 move linearly.
In one embodiment, ratio of free length of the helical spring to the length of syringe barrel (which is a travel distance of the piston) is greater than about 6:1. Ratio of free length to the solid length of the helical spring is greater than about 4:1. With these ratios, force decrease of the spring as displacement decreases at the beginning of travel (beginning of infusion) versus at the end of travel (end of infusion) should be less than 20%. The greater the ratio of free length versus the piston travel length is, the smaller the ratio of force decrease.
In embodiments, to avoid the size increase, springs are bent in a U-shape or J-shape.
In embodiments, the springs 320 and 322 do not have a portion that is located outside sidewalls of the syringe barrel 210 when viewing the springs 320 and 322 along the center axis. In this example, outer dimensions of syringe barrel 210 may define the width and the thickness of the apparatus.
The apparatus 100 according to embodiments provides better flow rate accuracy, i.e., least pressure (flow rate) variation from beginning of infusion to end of infusion. When combined with a pressure regulator, flow rate accuracy is even competitive with electronic pumps. Referring to
After completion of infusion, the syringe module 200 is separated from the actuator module 300. The separated syringe module 200 is discarded, and the actuator module 300 may be reused. For reusing the actuator module 300, the knob 352 is rotated in its locking state. The pressure plate 340 is pushed back to compress the springs 320 and 322. In the embodiment illustrated in
In one embodiment, a patient user can receive the infusion apparatus 100 in its assembled state from a supplier, for example, a pharmaceutical company, a health care provider or a pharmacist. In the assembled infusion apparatus 100, the actuator module 300 is engaged with the syringe module 200 that is filled with infusion fluid. After completion of infusion, a user can separate the syringe module 200 from the actuator module 300, and disposed the syringe module 200 while keeping the actuator module 300 for reuse.
In embodiments, a new syringe module 200 can be supplied to a patient user that uses a used actuator module from a medicine supplier, for example, a health care provider or a pharmacist. The user receives the syringe module 200 that is filled with infusion medicine. As shown in
Filling Syringe Module with Infusion Fluid
In another embodiment, an empty syringe module 200 is first engaged with the actuator module 300 as shown in
As discussed above, the configuration of the infusion apparatus according to embodiments of the invention provides the following advantages:
Although embodiments are described as above, it should be understood that numerous and various modifications can be made without departing from the spirit of the invention. Accordingly, the invention is limited only by the following claims.
