Multiple-dose syringe with collapsible container

A multiple-dose syringe including a barrel with a closed end and an open end, the closed end having an injection port that may be adapted to receive a needle, or that may be adapted to engage a commercially available needle-less system for fluidly connecting a syringe to an IV or a medicine vial. A plunger is slidably disposed through the open end of the barrel. A container is connected to an end of the plunger to move with the plunger. The container has a deformable shell with an opening at a forward end thereof and a predetermined quantity of fluid sealed therein by a closure member disposed over the opening to selectively seal the opening. The closure member includes a valve that opens in response to a fluid pressure differential across the valve. The container is slidably disposed in the barrel and includes a seal proximal to the forward end to form a first cavity in the barrel with a volume that is adjustable by moving the container in the barrel with the plunger so that fluid can be selectively drawn into and expelled from the first cavity, which is contiguous to the injection port. After at least a substantial portion of the fluid is expelled from the first cavity, the shell is configured to be collapsed by further pressure applied by the plunger, and after a predetermined fluid pressure differential across the closure member is reached, the valve of the closure member opens to allow expulsion of the quantity of fluid contained in the container.

FIELD OF THE INVENTION

The present invention relates to a syringe, and more particularly, to a syringe adapted to sequentially inject a plurality of fluids.

BACKGROUND OF THE INVENTION

When administering certain medications, it is sometimes necessary to inject sequentially two fluids into a patient. For example, during chemotherapy, small quantities of medicine are administered, usually through an intravenous catheter (i.e., commonly referred to as “IV,” and referred to below as an “IV”). To insure that all of the medicine reaches the patient, the medication is followed by a saline flush. The saline flush rinses any residual medicant through the IV and into the patient. Traditionally, the saline flush is administered as a separate step from the medicine. In particular, a standard single-dose syringe is used to deliver the medicine. A health care worker then, preferably, utilizes a second syringe containing the desired quantity of saline. The saline is then injected into the IV to flush the medicine into the patient. This process wastes time because it requires multiple operations, and wastes materials as it requires multiple syringes.

Various types of syringes for dispensing sequentially multiple fluid doses have been proposed to address the above problem. For example, U.S. Pat. No. 4,702,737 to Pizzino discloses a multiple-dose, single-barrel syringe utilizing a plurality of telescoping sections of progressively decreasing diameter. Unfortunately, the design of this syringe requires that all of its chambers be pre-loaded with fluids at the time of manufacture. In particular, the syringe incorporates a needle that extends into the barrel of the syringe to puncture a membrane to release the second fluid. The internal needle prevents the syringe from being completely closed to draw fluid into the barrel. As a result of the need to completely preload the syringe, it is necessary to stock separate syringes for each medication. Such medications are often expensive and have limited shelf life, thereby limiting the usefulness of this design.

U.S. Pat. Nos. 4,439,184, 4,715,854, and 5,720,731 to Wheeler, Viallancourt and Armata, respectively, disclose multiple-dose syringes with two pistons and a bypass zone. In each of these patents, a second chamber between the first and second pistons is filled and dispensed through the bypass zone, which is located on one side of the barrel wall near the injection port. Syringes with a bypass zone and multiple pistons are complicated to manufacture and require many specially designed parts. In most of the floating piston designs, the syringe must be preloaded with both fluids because the syringe cannot draw fluids or aspirate. In addition, the floating piston is subject to jamming and may thereby become difficult to depress.

DETAILED DESCRIPTION OF THE INVENTIONS

A syringe constructed according to the present invention is shown generally at10inFIG. 1. Syringe10includes a cylindrical hollow barrel12with a closed end14and an open end16. The cylindrical walls of the barrel define a cavity18, which is adapted to receive and hold the fluid to be dispensed. The cavity typically has a volume or capacity of between 1 and 10 cc, and is marked with gradations20to permit the amount of fluid to be measured. It should, or course, be understood, that the present invention could be implemented with syringes of any size. The closed end has an injection port22, which may be configured to receive a needle24. Alternatively and preferably, as shown inFIG. 9b, the closed end14has an injection port22configured for use with a needle-less coupling system to fluidly connect a syringe to an IV and/or a medicine vial, for example, the coupling system known under the Luer-Lok(™) trademark and manufactured by Becton, Dickinson and Company, Corp., the system used with a “Luer”-type syringe, or any other commercially available needle-less system for fluidly coupling a syringe to a medicine vial and/or an IV. The syringe12ofFIG. 9brepresents a typical needle-less syringe, and has an injection port22having an internally threaded sleeve160with internal threads162, and a hollow neck164for providing fluid communication between the cavity18and an IV. Alternatively, Finger grips26are disposed adjacent to the open end of the barrel and allow the user to grasp the barrel when drawing fluids into or dispensing fluids out of the syringe.

A fluid container28is slidably received into barrel12through open end16. As shown inFIG. 4, the container includes a cylindrical bellows-like shell30. The shell is preferably made of a flexible material that is non-reactive to the fluid stored therein. For instance, polypropylene is a suitable material when the container is used to hold saline. The flexible material allows the container to collapse to dispense fluid, as described in more detail below and illustrated inFIG. 3. It should be understood that other collapsible configurations besides a pleated or bellows structure could be used for shell30.

As shown inFIG. 5, a connector32is formed on a closed end of the shell. Connector32is joined by a coupler34to corresponding connector36formed on the end of a plunger38. Plunger38has an elongate shaft extending from connector36to a thumb pad40, which is shown inFIG. 1and is used to depress or retract the plunger. Coupler34is preferably formed of a butyl rubber compound and deforms to slip over the connectors. The connection between the container and the plunger allows the plunger to be used to move the container up and down in the barrel. As such, many other connections between the container and the plunger could also be used, including, for instance, glue or clips. Also, the plunger could be formed integrally with the container. As is apparent, one of the functions of the plunger is to compress the fluid container within the barrel.

The end of the shell opposite connector32includes a passage42that is selectively sealed by a closure member in the form of a cap44, as shown inFIG. 6. The shell includes a circumferential groove46that receives a corresponding flange48formed on the inside surface of the cap. The cap is preferably formed of a butyl rubber compound to allow it to be fitted over the end of the shell and retained thereon. The outer perimeter of the cap is shaped to form a perimeter seal50and sized to fit snuggly within the barrel, similar to the tip on a standard plunger. When the container is placed in the barrel, as shown inFIGS. 1–3, the perimeter seal effectively separates the barrel into two regions or cavities: a first region52disposed between the closed end and the cap and a second region54disposed behind the cap and occupied by the container.

An inwardly facing cup56is formed on the end face of the cap as shown inFIG. 4. The walls of the cup are received in a recess58formed in the end of the shell proximal to passage42. A slight outward tilt to the walls of the cup and recess serves to help retain the cap on the end of the shell. In particular, any pressure created in the fluid in the shell tends to urge the walls of the cup outward to tighten the seal between the cap and shell, thereby preventing the escape of fluid and preventing the cap from being pushed off the end of the shell.

The bottom of the cup forms a rupture zone60that is pressure rupturable, i.e. ruptures when fluid pressure across the rupture zone exceeds some desired level. For instance, the thickness of the rupture zone may be varied to control the pressure at which rupture occurs. Alternatively, a defect may be created in the rupture zone to provide a predetermined failure location. For example, the defect can be a cut extending part-way through the material of the cap or a series of partial perforations. In general, however, the rupture zone should fail at a relatively predictable pressure. Furthermore, the pressure should be readily achievable by finger pressure on the thumb pad of the plunger. It should be noted that any pressure created in the shell is matched by backpressure of the fluid in the first region. Therefore, zone60will not rupture until all the fluid in the first region is substantially expelled. The dashed lines inFIG. 6depict the rupture zone after rupture.

An alternative cap structure62is shown inFIG. 7and includes a rupture sheet64disposed over passage42. The rupture sheet is preferably formed of a thin sheet of rubber, plastic or non-corrosive metal. The rupture sheet is supported and retained against the end of the shell by a seal flange66with a central aperture68aligned with passage42. The aperture allows fluid to pass after rupture of the sheet. The seal flange is held in place on the end of the shell by a clamp ring70that is crimped over the end of the shell. The clamp ring is preferably formed from a thin deformable cylinder of metal, such as used on the end of a medicine vial. A seal72, preferably formed of a butyl rubber compound, is disposed over the clamp ring to form a seal with the walls of the barrel, as previously described. The clamp ring and seal include apertures74and76, respectively, that allow fluid from the container to pass after the sheet is ruptured, as shown by the dashed lines inFIG. 6.

FIG. 8depicts the steps involved in using a syringe according to the present invention. First, the operator selects a pre-loaded syringe package and removes the sterile envelope. The fluid container of the pre-loaded syringe package is preferably pre-loaded with a secondary fluid, such as saline. If necessary, a needle may be attached to the barrel. The syringe is then fluidly connected, either by a needle or through a needle-less system (such as shown inFIG. 9b), to a vial containing a primary fluid, such as a medicine. The operator then loads the desired amount of primary fluid, such as a medicine, into the syringe similar to loading a conventional syringe. This is possible because the plunger/container functions like a standard plunger until the medicine in the forward region is expelled. Thus, the operator can retract the plunger to load air into the syringe, connect the syringe to a medicine vial, push forward on the plunger to inject the air into the vial and then retract the plunger again to withdraw the desired amount of medicine. The syringe is then fluidly connected to an IV, either by the insertion of a needle or through a needle-less system (such as shown inFIG. 9b), and the medicine is dispensed by depressing the plunger, as shown by comparison ofFIGS. 1 and 2. When the medicine (or other primary fluid) is dispensed, subsequent pressure on the plunger causes a greater fluid pressure differential across the closure member thereby causing the closure member to open, for example, by rupturing (as illustrated inFIGS. 6 and 7), or, preferably, by the opening of a valve (for example, the best mode valve ofFIGS. 9,9a,9b,11, and12, or the valve ofFIGS. 14,15,16, and17, or the valve ofFIG. 18), thereby releasing the saline or other fluid in the container. The plunger is then further depressed to compress the container, as depicted, for example, inFIG. 3, thereby forcing the saline or other secondary fluid in the container out of the container to flush the medicine (or other primary fluid) through the IV with the saline or other secondary fluid.

Alternatively, the best mode of practicing the inventions claimed herein is shown inFIGS. 9 and 9a, which illustrate an alternative embodiment of a multiple-dose syringe77with a closure member78including a valve that opens in response to a fluid pressure differential. Syringe77includes the cylindrical hollow barrel12discussed above, including a closed end14and an open end16. As discussed above, the closed end14has an injection port22which is configured to receive a needle.

The syringe77further includes a closure member78, a fluid container79, plunger80, which includes a thumb pad81and elongate shaft81a. As shown inFIG. 9, the closure member78is slidably received into barrel12through open end16.

The fluid container79is shown in more detail inFIGS. 10 and 19. As shown inFIGS. 9,9aand10, the fluid container79has a cylindrical bellows-like collapsible shell79a. The above discussion regarding the construction of shell30apply equally to shell79a, unless noted otherwise below. Fluid container79has an open end81and a closed end84. As shown inFIG. 10, at the open end81, there is a neck portion82, and a sealing portion83, which is larger in diameter than neck portion82. While various manufacturing methods will be apparent to those skilled in the art, the preferred method of manufacturing the fluid container79is by blow molding since this method will yield a container with an approximately consistent wall cross-sectional area. Low density polyethylene (LDPE) is most appropriate given the desire for flexibility and the possibility for radiation sterilization. Ethyl Vinyl Acetate (EVA) preferably may be added in a small percentage to enhance flexibility.

The closure member78is shown in more detail inFIGS. 11 and 12. The closure member78preferably is made either of a synthetic rubber (such as polyisoprene) or silicone. Other materials will be readily apparent to these skilled in the art. Since silicone is more compatible with the preferred method of gamma sterilization, silicone is the preferred material. A silicone material of a low durometer value is preferred to provide the necessary stretch (for the proper operation of the valve portion described below) and a wide compression range (for proper operation of the various sealing ribs described below).

As shown inFIG. 11, the closure member78has two external sealing ribs, a primary sealing rib84and a secondary sealing rib85. When the closure member is slideably received into barrel12through open end16(as shown inFIG. 9), because the sealing ribs are of slightly greater diameter than the inner diameter of the barrel, a sealing force is concentrated to the localized area of the sealing ribs84and85, thereby optimizing sealing pressure and minimizing the frictional load. The sealing rib84closest (when assembled as shown inFIG. 9) to the injection port22is the primary seal, and is preferably higher relative to the surface86of the closure member78than the secondary sealing rib85. Since the primary sealing rib84is higher, it undergoes the greatest compression (when assembled into the barrel12). The secondary sealing rib85, being slightly lower, provides a redundant seal without doubling the frictional load. The secondary sealing rib85also acts as a wiping seal to protect the primary sealing rib84from accidental environmental particulate exposure. Preferably, as shown inFIG. 12, both the primary sealing rib84and the secondary sealing rib85have a flat contact portion bordered by tangent radii to reduce the likelihood of seal extrusion under pressure. It should be understood that the closure member78accomplishes the function of sealing between the fluid container79and the barrel12, or, alternatively, this function could be performed by a separate member.

Turning to the interior of the closure member78, as shown inFIG. 12, the closure member78has an interior cavity87adapted to receive the neck portion82and the sealing portion83of the fluid container79. The closure member78has two internal sealing ribs88in the interior cavity87. The closure member78also has a shoulder88a.When the fluid container79is assembled as shown inFIGS. 9 and 9ainto the closure member78, the two sealing ribs88are compressed and engaged by the sealing portion83(shown inFIG. 10), thereby forming a fluid-tight seal. Alternatively, one seal or three or more sealing ribs could be used. In addition, other sealing means will be readily apparent to those skilled in the art, and are included within the invention claimed herein. When assembled as shown inFIG. 9a, the closure member78is held on the fluid container79by the engagement of the shoulder88awith the sealing portion83.

When assembled (as shown inFIGS. 9 and 9a), the fluid container79is selectively sealed by the closure member78. In addition, when assembled, there exists a first cavity (like first region52,FIG. 1) between the closure member78and the injection point22, and a second cavity inside the fluid container79. The seal formed by the closure member78as to the fluid container79is selective because the closure member78seals a second fluid in the fluid container79but allows the second fluid in the fluid container79to be expelled when the fluid pressure differential across the closure member78(between the first and second cavities) exceeds a predetermined limit.

To allow expulsion of liquid from the fluid container79when the pressure differential across the closure member78exceeds a predetermined limit, the closure member78includes a valve89(shown inFIGS. 11 and 12), which functions as a valve that resembles in operation a poppett or diaphragm valve. The closure member78also includes a boss portion92. The valve89is recessed into the closure member78as shown inFIGS. 11 and 12, being surrounded by the boss portion92.

The valve89has an interior sealing surface90as shown inFIG. 12. The valve89of closure member78also has several holes, and in the preferred embodiment, four holes91as shown inFIG. 11. When assembled as shown inFIGS. 9,9a, and9b, the neck portion82engages the sealing surface90of valve89of closure member78. In addition, the length of the neck portion82and the location of the valve89are such that, when assembled, the neck portion82stretches the valve89of the closure member78, towards the boss portion92. This stretch creates a resisting force within the valve89, and the resulting force against the neck portion82creates a pre-load pressure that serves to contain the second fluid in the fluid container79until a predetermined pressure differential across the valve89is exceeded. As shown inFIGS. 9aand9b, the valve89when assembled is of a flatter shape than that shown inFIG. 12due to the stretching of the valve89.

As shown inFIGS. 9 and 10, the fluid container79has a protuberance94at the closed end of84for engaging a slot93in the plunger80defining a cavity to contain a fluid. When assembled as shown inFIGS. 9,9a, and9b, the fluid container79is connected to the plunger80. Also shown inFIG. 9, the thumb pad81is separate from the elongate shaft81a, and engages by a snap-fit to the elongate shaft81a.However, as readily apparent to one skilled in the art, the plunger80could be an integral component having a thumb pad and elongate shaft as shown inFIGS. 1–3. Alternatively, instead of a protuberance94and slot93, a coupler34as previously described (inFIG. 5) could be used. It is also contemplated that the plunger80and the fluid container79could be formed as an integral component.

In operation, when assembled as shown inFIGS. 9,9a, and9b, the multiple-dose syringe77functions similarly to the multiple-dose syringe10described above. An operator loads the desired amount of a first or primary fluid (such as a medicine) for injection into the syringe77similar to loading a conventional syringe, that is, by retracting the plunger80. The fluid container79will preferably be pre-filled with a secondary fluid, for example, saline. Alternatively, the fluid container could be loaded by a user with the secondary fluid prior to assembling the syringe77. After fluidly connecting the syringe to an IV (using either a needle-less system such as those discussed above or a needle), the fluid held in the barrel12is expelled from the barrel by pressing on the thumb pad81until the boss portion92contacts the closed end14of the barrel12, thereby having expelled virtually all of the first fluid. The valve89of the closure member78is recessed so as to protect the valve89from impact with the closed end14of the barrel12. Upon impact of the boss portion92of the closure member78, the user will continue to apply pressure to the thumb pad81, thereby causing a pressure differential across the valve89, which pressure differential is greater than that present during expulsion of the first fluid from the barrel12. The greater pressure differential causes the valve89to stretch a small additional amount, thereby allowing the second fluid held in the fluid container79to flow from the fluid container79through the holes91of the closure member78, and into and through the injection port22, thereby flushing the first fluid.

In the operation of the multiple dose syringe77described above, as well as in the operation of the multiple-dose syringe10described above, once all of the fluid has been expelled from the fluid container79, (or, alternatively,28) it has been found that the bellows-type fluid container79(or28) may tend to move a small amount toward its original position due to the spring-like nature of the bellows. This tendency is undesirable because it tends to aspirate a small amount of fluid into the syringe. To counteract and prevent this movement, in one alternative embodiment of plunger80(or38), a detent95in the form of a triangle (95ashown inFIGS. 13aand13c) or a circular disk (95b,shown inFIGS. 9aand13b) has been added as shown inFIGS. 13a,13b, and13crespectively. Other variations will be readily apparent. A conventional barrel12has a ridge or ring96(shown inFIGS. 9aand13c). The apparent purpose of the ridge or ring96of the conventional barrel12is to prevent or at least discourage a user from pulling the plunger80(or38) completely out of the barrel12by acting as a stop for a conventional plunger. The detent95is located such that the detent will snap past the circular ridge or ring96that is present on a conventional barrel12when the plunger80(or38) is fully depressed. The detent95is sized such that the user may readily push the detent95past the ridge or ring96of the barrel12, but the spring action of the bellows-type fluid container (79or28) is insufficient to push the detent95across the ridge or ring96toward the open end of the barrel12.

As an alternative embodiment to the closure member in the form of a cap44shown inFIG. 6, as an alternative to the cap structure62shown inFIG. 7, and as an alternative to the closure member78shown inFIGS. 9,11, and12,FIG. 14shows the fluid container28closed by a closure member including a valve141. The valve141is preferably a valve that opens when the pressure in the container28exceeds some desired level (with respect to the pressure in the first region52). One embodiment of the valve141operates much like a “Heimlich”-type valve, which is well known in the medical arts. The “Heimlich” valve was described in U.S. Pat. No. 3,463,159. A “Heimlich” valve consists of a pair of elastic membranes or sheets having a slit between them through which fluids may flow in one direction. This type of valve has been used in a variety of industries, see, e.g., U.S. Pat. No. 4,261,362, and will be readily familiar to a person skilled in the art. A similar valve is found in the well-known “whoopie” cushion found in any toy store. A similar valve has also been referred to as a “condom”-type valve (See U.S. Pat. No. 4,738,672), and could also be used in modified form. The valve141may be considered a Heimlich-type valve except that the opposing walls (elements150and151, shown inFIG. 15) of the slit140are not as long, i.e., the thickness of valve141is not as thick, as the “rubbery tube” of the Heimlich valve shown in the '159 Patent.

In the embodiment shown inFIG. 14, valve141consists of a circular elastic membrane with an outer perimeter shaped to form a perimeter seal50such as shown inFIG. 6. The valve141inFIG. 14is shown in the closed state. The valve141is composed of an elastomer or similar compound, and preferably a butyl or nitryl rubber compound. Other suitable materials will be readily apparent to those skilled in the art. Valve141ofFIG. 14includes a slit140through the entire thickness (shown for example, as “t” inFIG. 17) of the valve141. The slit140is held closed by the elasticity of the compound. As noted above, pressure in the container28is matched by backpressure of the fluid in the first region52. Therefore, the valve141will not open until the fluid in the first region52is substantially expelled, as illustrated inFIG. 15. As shown inFIG. 15, the valve141is in the open state, as slit140is open, allowing fluid to pass from the container28into the first region52.

An embodiment of the valve141is shown inFIG. 16. It will be apparent to one skilled in the art that the length of the slit140and thickness (t, shown inFIG. 17) will depend on the diameter of the container28. For some sizes, it may be desirable to form a raised region160on the outward facing surface161(shown inFIG. 16andFIG. 17). The raised region160has a greater thickness than t (shown inFIG. 17). The purpose of the raised region is to provide more surface area for the opposing walls150and151of the slit140, thereby providing a better, more positive seal. Other such variations should be apparent to a person skilled in the art.

It should also be understood that the valve141may also include a perimeter seal, similar to perimeter seal50shown inFIG. 6, and a corresponding flange, similar to flange48ofFIG. 6, to attach the valve to the container28. As an alternative, the valve141could also be attached to the container28as shown inFIG. 7. Alternatively, any other suitable means to attach the valve141to the container28could be used so long as such means provides a seal between the container28and the valve141such that fluid substantially only passes through the valve141, and in the illustrated embodiment, through slit140. In the embodiments shown inFIGS. 6 and 7, the perimeter seal50, or alternatively, seal72, form a seal between the container28and the walls of the barrel12. It should be understood that the valve141could be formed to accomplish this function of sealing between the container28and the barrel12, or alternatively, this function could be performed by a separate member. It is contemplated that the plunger80or38and the container28could be formed as a single integral component.

FIG. 18illustrates yet another alternative to valve141shown inFIGS. 14–17.FIG. 18illustrates a valve similar to valve141discussed above, except that, instead of a single slit140, the valve ofFIG. 18has three slits102a–cof equal length, arranged symmetrically as shown. Alternatively, any number of slits could by used, of the same or different length, arranged symmetrically or asymmetrically.

The present invention is not limited to a single slit-type, Heimlich-type, whoopie cushion-type, condom-type, poppett, or diaphrahm valve, but includes any suitable valve that, when included within a closure member attached to the container28, operates to allow the fluid to pass from the container when the pressure differential across the closure member, or more precisely, the valve, exceeds some desired level.

It can be seen that the inventions described herein provide an economical and easy to use solution to the problem of sequentially injecting two fluids. The simple operation saves time and materials (i.e, one versus two syringes).

As described above, the syringe of the present invention is preferably pre-loaded or filled with saline or other second fluid at the time of manufacture. The plunger is also attached to the container and the resulting assembly is packaged in a sterile condition for shipment. A needle may or may not be attached, depending on the configuration desired. It should be noted that the barrel of the present invention is preferably an unmodified component from a standard syringe design. This eliminates the need to create new and specialized parts for use with a two-fluid syringe. Although it is preferred that the container be pre-loaded in the syringe, it should also be understood that the container could be provided as a separate unit for installation and use with an otherwise standard syringe. This variation is facilitated by use of a design that incorporates one or more unmodified parts from a standard syringe.

The foregoing description of the present invention has been presented for purposes of illustration and description. The specific embodiments thereof as disclosed and illustrated herein are not to be considered in a limiting sense as numerous variations are possible. Applicant regards the subject matter of the invention to include all novel and non-obvious combinations and subcombinations of the various elements, features, functions and/or properties disclosed herein. No single feature, function, element or property of the disclosed embodiments is essential. Consequently, the invention and modifications commensurate with the above teachings and skill and knowledge of the relevant art are within the scope of the present invention. It is intended that the description be construed to include all alternative embodiments as permitted by the prior art.