Patent Application
20110139650
The present invention is directed to a package for sterilizing articles, and more particularly, a package for the packaging and sterilization of medical devices.
Generally, it is desirable to sterilize medical instruments and devices after packaging and prior to being sent to the end user. Common forms of sterilization include irradiation; autoclaving, and treatment with a sterilizing gas, such as ethylene oxide. Typically, treatment with a sterilizing gas is used to sterilize many such instruments and devices. For example, one conventional form of package for sterilizing medical devices, such as a stent, comprises a polymeric sheet and a sheet of a breathable material, such as Tyvek®, that are attached to each other along their peripheral edges to form seams defining a pouch. The breathable material is typically a sheet material that is a microbe barrier and is gas pervious. Another common package for packaging of medical devices is a blister-type package in which a sheet of breathable material it sealed to the peripheral edge of a tray to form a lidding. After an article has been sealed in one of these types of packages, a sterilizing gas can then be introduced into the interior of the package through the breathable membrane. These types of packaging have several disadvantages.
In particular, breathable materials, such as Tyvek®, can typically only be heat sealed below a given temperature due to melting of the material, which limits the speed at which such packages can be manufactured. Opening of the package by the end user can also present some issues. Tyvek®, which is widely used as a microbe barrier material, is a nonwoven sheet material made of individual fibers that are thermally bonded to each other to form a coherent fabric. Opening of a package that includes a breathable material along a seam may result in the creation of small fibers that may be deposited on the sterilized article. In addition, seams comprising a breathable material and a polymeric material are typically weaker than a seam that is between two polymeric materials.
Such conventional packaging for stents and other medical devices/instruments are generally considered inefficient and wasteful of material and labor. Accordingly, there is a need for a more cost and labor effective method for the packaging and sterilization of medical devices and instruments.
In one embodiment, the present invention is directed to a sterilizable package having a support member that is disposed in a pouch comprising a barrier sheet material that includes a breathable membrane. The breathable membrane comprises a breathable material that is pervious to gases, and substantially impervious to microorganisms. The breathable membrane allows a sterilizing gas to be introduced into an interior space of the sterilizable package. In one embodiment, the sterilizable package includes a pouch in which the sheet material is folded and sealed to itself along opposing side seams and a longitudinal seam to define the pouch. The breathable membrane is preferably disposed towards a central portion of the sheet material and is not present where the sheet material is sealed to itself or another sheet material. It has been discovered that by positioning the breathable material towards a central portion of the sheet material and away from the seams forming the pouch, the strength of the seams is increased in comparison to packaging in which a breathable material is part of the seam. Further, by not including a breathable material as part of the seam, fiber tearing during opening of the package can be avoided. In addition, by spacing the breathable membrane away from the seam forming the package, the present invention makes it possible to use less breathable material, in the lidding or the pouch while still being able to maintain a desired level of sterilization.
In a preferred embodiment, the sheet material includes an opening formed therein for providing communication between the outside and interior of the sterilizable package. A breathable membrane comprising a microbe barrier, gas permeable sheet material is disposed on an inner or outer surface of the sheet material and covers the opening. The breathable membrane includes a peripheral edge overlying the sheet material and that is spaced from the seams forming the pouch. A continuous seam is located at or adjacent to the peripheral edge of the breathable membrane and joins the membrane to the sheet material.
In one embodiment, an article to be sterilizable is introduced into and sealed within the sterilizable package. Thereafter, a sterilizing gas can be introduced into the sealed package containing the article via the breathable membrane.
In a further aspect of the invention, a sterilizable package is provided comprising a support member to which the sheet material having the breathable membrane is affixed to form a lidding of the sterilizable package. As in the embodiment discussed above, the breathable membrane is not part of the seal between the support member and the sheet material.
Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the inventions are shown. Indeed, these inventions may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.
The present invention provides sterilizable packages that include a sheet material having a breathable membrane through which a sterilizing gas can be introduced into the interiors of the packages for sterilizing the contents of the package. The breathable membrane comprises a breathable material through which a gas, such as a sterilizing gas can be introduced into the interior of the package. The present invention also provides for sterilizable packages that are formed from the sheet material, and for processes of making such sterilizable packages. In particular, the sheet material having the breathable membrane can be used in a variety of packaging applications including, but not limited to horizontal-form-fill-seal (HFFS), vertical-form-fill-seal (VFFS), vacuum skin packaging (VSP), flow wrap packaging, thermoforming packaging, and the like. The barrier sheet material having the breathable membrane may also be used as a lidding for packages comprising a support member (e.g., tray) to which the sheet material has been adhered. For example, in one embodiment, the sheet material may be heat sealed to a support member, such as a tray, to form a sealed sterilizable package.
In addition, sterilazable packages in accordance with the present invention can also be used in packaging applications where a change in pressure may result in rupture of the package. For example, in the case of air transport of a sealed package, a change in pressure may cause the seams of the package to rupture upon a change in pressure if the atmosphere within the package cannot escape. In the present invention, the breathable membrane provides a means from which air may ingress or egress out of the interior of the package. As a result, the sterilazable packages of the present invention may advantageously be used in packaging applications in which the sealed package is transported/shipped via an air carrier.
Sterilizable packages in accordance with the present invention can be use to package a variety of different articles including medical instruments and devices. For example, the sterilizable package can be used to package and sterilize scalpels, scissors, sutures, forceps, retractors, blades, clamps, stents, both treated and untreated, catheters, etc.
With reference to
The pouch is formed from a polymeric sheet material 24 that is substantially impervious to microorganisms. The pouch includes one or more breathable membranes 26 comprising a breathable material 28 through which a gas, such as a sterilizing gas, can be transmitted into and out of the pouch. The breathable membrane preferably comprises a sheet material that permits the passage of gases while limiting the passage of undesirable materials, such as microorganisms. Suitable materials for the breathable membrane include nonwovens, medical grade paper, microbial barrier membranes, and other porous materials that limit the passage of microbes. In the context of the invention, the term “pouch” is used in a generic sense and should be recognized to include, sacks, bags, satchels and the like.
Turning to
The opening 30 can be made in the sheet material in a variety ways as known in the art, including punching, die cutting, cutting, and the like.
The breathable membrane comprises a material that is a barrier to microorganisms, but is permeable to gases including oxygen, carbon dioxide, and various sterilization gases. Suitable materials for the breathable material may include paper and nonwoven sheet materials. Suitable nonwoven sheet materials include spunbond nonwoven fabrics such as Typar® and Reemay® fabrics from Fiberweb Inc., and nonwoven fabrics formed of flash-spun polyethylene strands, such as a nonwoven sheet material sold by E.I. Du Pont de Nemours and Company under the trademark Tyvek®.
The breathable membrane is positioned on the sheet material, and hence the pouch, so that it is spaced away from the seams forming the pouch (e.g., side seams 14, 16 and longitudinal seam 18). By positioning the breathable membrane towards a central portion of the sheet and away from the seam(s) forming the pouch, the strength of the seams can be greatly improved. In addition, since the breathable membrane is not part of the seal between an opposing sheet material or tray, tearing of the breathable membrane, which may result in fibers being deposited on the packaged article, during opening of the package can be limited or avoided.
The breathable membrane has a surface area that is generally from about 10 to 60% larger than the surface area of the opening formed in the sheet material, and in particular, from about 20 to 50% larger than the surface area of the opening formed in the sheet material. For example, in the illustrated embodiment, the opening has a diameter that is about 3 inches, whereas the breathable membrane has a diameter that is about 5 inches. In this embodiment, the large sized breathable membrane helps to provide more freedom in the manufacturing process so that the breathable membrane does not have to be precisely positioned over the opening prior to sealing the breathable membrane to the sheet material.
The breathable membrane generally overlies between about 2 and 25 percent of the surface area of the sheet material. In one embodiment, the breathable membrane overlies between about 5 and 10 percent of the surface area of the sheet material, and more typically between about 5 and 15 percent of the surface area of the sheet material. It should be understood that the size and location of the breathable membrane is not limited to any particular configuration and that the position and size can be selected to meet the particular requirements of the end user. Additionally, the position and size of the breathable membrane can be selected to optimize the sterilization process.
In the figures, the sheet material is depicted as having a single breathable membrane having a generally circular shape. However, it should be recognized that the present invention is not limited to any particular number, shape or size of the breathable membrane and that the sheet material can include multiple breathable membranes of varying shapes and sizes. It should also be recognized that the opening in the sheet material is not limited to any particular size or configuration. For example, the opening may comprise one or more slits or smaller openings depending on the design and/or end application.
In embodiments in which the breathable membrane has a circular shape, the diameter of the breathable membrane can generally range from about 1 to 10 inches, with a diameter of about 2 to 5 inches being preferred.
As can best be seen in
Alternatively, the pouch 12 can be prepared from two separate sheets of material that are oriented in a face-to-face relation, and are sealed to each other along opposing edges to define a pouch having an interior space for receiving the support member therein.
Preferably, the inner surface 34 of the sheet material 24 comprises a heat sealable material. In the particular embodiment illustrated, the sheet material is made from a heat sealable material and the opposing ends of the pouch are sealed by producing a fusion bond or seal between contacting interior surfaces of the sheet material 24 using pressure and heat or ultrasonic energy as is well known. Although referred to herein as “heat seals”, it should be understood that this term is intended to apply both to seals formed by heating the contacting surfaces with a heated anvil or platen, as well as to heating and fusion produced by other methods, such as application of ultrasonic energy. As discussed in greater detail below, suitable polymeric sheet materials for use in the present invention may include polyolefins, such as polyethylene and polypropylene, polyesters, nylons, etc.
As noted above, the support member 20 provides a component of the sterilizable package on or in which the article to be sterilized is disposed. The support member of the sterilizable package may be flat or substantially planar but is preferably formed in the shape of a tray. Preferably, the support member includes a downwardly formed cavity and an upper flange, wherein the product support surface is defined by the downwardly formed cavity and wherein the upper flange is the periphery of the support member. In this regard,
The support member may be semi-rigid but is preferably rigid, and is not limited to any particular shape or configuration. For example, the support member can be rectangular, round, oval, etc. Similarly, flange 48 may have any desired shape or design, including a simple, substantially flat design which presents a single sealing surface as shown, or a more elaborate design which presents two or more sealing surfaces. In the case of HFFS and VFFS packaging, it may be desirable for the support member to have a rectangular or square shape.
Suitable materials from which support member 20 can be formed include, without limitation, polyvinyl chloride, polyethylene terephthalate, polystyrene, polyolefins such as high density polyethylene or polypropylene, paper pulp, nylon, polyurethane, etc. The support member may be foamed or non-foamed as desired, and preferably provides a barrier to the passage of oxygen therethrough. In some embodiments, the support member 20 may be formed from a material which itself provides a barrier to the passage of oxygen, e.g., vinylidene chloride copolymer, nylon, polyethylene terephthalate, ethylene/vinyl alcohol copolymer, etc. Alternatively, support member 20 may have a substantially gas-impermeable sealant film laminated or otherwise bonded to the inner or outer surface thereof.
In one embodiment, the support member comprises a thermoplastic material that is thermoformed into a desired shape. In this regard,
In embodiments in which the support member is thermoformed, the support member may be thermoformed in-line with the packaging operation or provided preformed. Depending on the product being packaged and the ultimate end-use application the support member may be gas permeable or substantially gas impermeable. Additionally, depending on the composition of the inner surface of the sheet material (i.e., the surface affixed to the support member) the support member may comprise a heat sealable material. For example, the support member may include a sealant film for heat sealing the support member to sheet material 24.
As in the sterilizable package discussed above, the breathable membrane 26 is positioned on the sheet material so that it is spaced away from seal 56 so that the breathable membrane is not part of seal 56. In a preferred embodiment, the support member 52 comprises a thermoplastic material has been thermoformed into a tray as is known in the art.
Seal 56 can be made peelable so that the lidding 54 can be easily removed during use. In peelable applications, the peal strength of seal 56 is typically about 0.5 to 4 pounds per inch. In contrast to prior art packaging applications in which the lidding or a sheet of the pouch comprises a sheet of the breathable material, such as Tyvek®, the present invention makes it possible to use less breathable material, in the lidding or the pouch while still being able to maintain the same sterilizable properties, and also makes it possible to prepare peelable applications that do not need a coating on the breathable material, such as a coated Tyvek®.
As discussed above, the one or more breathable membranes are positioned at locations on the sheet materials so that upon forming a package from the sheet material, the breathable material of the breathable membrane does form part of the seal forming the packaging. Preferably, the breathable membranes 26 are positioned towards the center of the sheet material and away from the longitudinal side edges 40, 42 of the sheet material. For example, the breathable membranes 26 are generally spaced away from the side edges 40, 42 by at least 1 cm, with a spacing of at least 2 cm being preferred, and a spacing of at least 3 cm being even more preferred.
Sheet materials in accordance with the present invention may be used as stock roll for standard equipment adapted to fabricate bags, pouches, or other dilatable products, by slitting, sealing, folding and whatever other operations are dictated by the form of the product. In particular, the sheet material is particularly useful in vertical form fill and seal (VFFS), horizontal form fill and seal (HFFS) packaging processes, lidding in thermoforming applications, vacuum seal packaging, and the like.
The sheet material itself, comprises a flexible polymeric film having microbe barrier properties. In a preferred embodiment, the sheet material is a polymeric film having liquid, moisture vapor, and gas barrier properties. In one embodiment, polymeric films for as the sheet material have an oxygen vapor transmission rate that is less than about 1 cc/m2/day, and in particular less than about 0.5 cc/m2/day, and more particularly less than about 0.2 cc/m2/day as measured according to ASTM test method 3985.
Sheet material 24 may be in the form of a mono-layer, multi-layer film, or laminate. In one embodiment, the sheet material 24 comprises a multilayer film including one or more polymeric or other layers composed of compositions selected to impart specific properties to the film. In one embodiment, the sheet material has barrier properties. Suitable components the sheet material may include metallic foil, such as aluminum foil, and metallized films, such aluminized films, aluminum oxide films (AlOx), silicon oxide films (SiOx), and films comprising polychlorotrifluoroethylene (PCTFE) such as Aclar®. The sheet materials may also include polymeric components having barrier properties, such as ethylene/vinyl alcohol copolymer (“EVOH”), polyvinyl alcohol (“PVOH”), vinylidene chloride polymers (“PVdC”), polyalkylene carbonate, polyester (e.g., PET, PEN), polyacrylonitrile (“PAN”), and polyamides.
Useful polyamides may include polyamide 6, polyamide 9, polyamide 10, polyamide 11, polyamide 12, polyamide 66, polyamide 610, polyamide 612, polyamide 61, polyamide 6T, polyamide 69, copolymers made from any of the monomers used to make two or more of the foregoing homopolymers (e.g., copolyamide 6/12, polyamide 12, copolyamide 66/69/6I, copolyamide 66/610, copolyamide 6/66, and copolyamide 6/69), and blends of any of the foregoing homo- and/or copolymers.
Polymeric films suitable for use as sheet material may include one or more additional layers that impart desired properties to the film. For example, the sheet material may include one or more of: outer abuse layers, sealant layers, tie layers, etc. In one embodiment, the front and back sheets include an outer abuse layer. During manufacturing, processing and shipping, the package, and hence the sheet material, may be exposed to environmental stresses, such as abrasion, high temperatures, and the like. As such, it may be desirable for the sheet material to include an outside or abuse layer that provides enhanced resistance to abuse. Further, since the abuse layer may be directly exposed to a heat seal bar of the heat-sealing equipment when forming the sterilizable package, the abuse layer preferably provides heat-resistant characteristics to the outer surfaces of the front and back sheets to help prevent “burn-through” during heat sealing. Suitable polymers for the abuse layer may include one or more of any of the following: polyolefins (e.g., polyethylenes, polypropylenes), polyamides, polyesters, polystyrenes, polyurethanes, and polycarbonates. Examples of suitable polyesters include amorphous (co)polyesters, poly(ethylene/terephthalic acid), and poly(ethylene/naphthalate). In a preferred embodiment, the front and back sheets include an outer abuse layer comprising polyester terephthalate.
The sheet material may also include a sealant layer on the opposite side of the sheet material from the abuse layer. The sealant layer typically defines an inner surface of the sterilizable package that faces the interior space of the package. The polymer material (i.e., component or blend of components) that forms the sealant layer has a melting point that facilitates heat sealing the inner surface of the sheet material to either itself, such as in the embodiment illustrated in
In one embodiment, the sheet material may comprise a multilayer laminate having an inner foil layer, such as aluminum foil. In this embodiment, the foil layer in addition to providing moisture and gas barrier properties also provides UV barrier properties. In a preferred embodiment, the sheet material comprises a laminate having an interior aluminum foil layer that is disposed between one or more polymeric layers. For example, a preferred laminate for use as the barrier film of the sheet material comprises a seven layer laminate having the following structure: an outer abuse layer comprising polyethylene terephthalate, a low density polyethylene layer, an inner aluminum foil layer, a nylon layer, a low density polyethylene layer and a sealant layer comprising low density polyethylene/ethylene vinyl acetate. In this embodiment, the low density polyethylene/ethylene vinyl acetate is heat sealable to itself or to the support member.
Sterilizable packages in accordance with the present invention may be prepared from a variety of suitable plastic materials whereby a strong, lightweight, reliable, yet economic package is provided. Preferably, the sheet material comprises a plastic material having an inner surface capable of forming a strong heat seal with itself or a support member. Additionally, packages for use in medical applications are generally formed from sheet material having both moisture barrier properties and gas barrier properties.
With reference to
At heat sealing station 76, a longitudinal heat seal extending in the machine direction of sheet material is formed joining the two opposing edges 40, 42 of the sheet material to each other and thereby form longitudinal seam 18. Next, opposed heat sealing bars 78, 80 are used to heat seal the sheet material to itself to form seams 14, 16, and thereby form the sterilizable package. In the illustrated embodiment, heat sealing bars 78, 80 are depicted as each including a pair heat sealing bar for simultaneously creating seams 14 and 16 on successive packages. However, it should be recognized that such seams cannot be created in separate steps.
After the packages are formed and sealed, a sterilizing gas is then introduced into the into the interior of the package through breathable membrane 26. The sterilizing gas is introduced into the package for a sufficient amount of time so that the article is sterilized.
In some embodiments, the sterilizable package is flushed with an inert gas, such as nitrogen, prior to being filled. Additionally, a vacuum can also be applied to the interior of the sterilizable package prior to final sealing.
As should be evident from the foregoing discussion, the present invention can be used to package a wide variety of different items in which sterilization is desirable. In one particular embodiment, the present invention can be used to package a wide variety of medical devices and instruments including catheters, stents, and in particular drug coated stents.
Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
