Chemical apparatus and process disinfecting – deodorizing – preser – Physical type apparatus – Apparatus for treating solid article or material with fluid...
Reexamination Certificate
2000-08-08
2004-10-26
Jastrzab, Krisanne (Department: 1744)
Chemical apparatus and process disinfecting, deodorizing, preser
Physical type apparatus
Apparatus for treating solid article or material with fluid...
C053S128100, C053S453000, C206S323000, C206S363000, C206S439000, C422S297000, C422S300000
Reexamination Certificate
active
06808691
ABSTRACT:
The present invention relates to a sealable sterilizing packaging material for medical devices that have to be sterilized as well as to the sterilizing package itself.
Sealable sterilizing packages for medical devices that have to be sterilized, especially reusable instruments or devices, such as probes, scalpels, clamps, scissors and needles, are already known.
In fact, to sterilize the medical devices, it is possible to use a heat- and/or pressure-sealable sterilizing package which may be a flexible or semi-rigid package, in the form of a sachet, a bag, a sheath or a blister pack, or else a rigid package.
The rigid package is a container consisting of a receptacle, generally made of plastic and thermoformed, which will contain the medical devices to be sterilized and which will then be closed by a cover which may be a sealable sheet of paper acting as a barrier to microorganisms. This sheet is a barrier sheet similar to that used for the other type of package described below.
The flexible or semi-rigid package in the form of a sachet, a bag, a sheath or a blister pack is a package consisting of a part (
1
), which may be made of synthetic material, and of a sheet of paper (
2
) having a specific permeability, these being sealed together along a certain perimeter according to the shape desired for the package, a relatively large opening being left so as to introduce the articles. The articles to be sterilized are placed inside the package and then the said package is completely sealed. The part (
1
) made of synthetic material may be a thermoplastic film such as polyethylene or polypropylene film. This film is generally impermeable to gases and to steam and, in addition, is transparent so as to see the contents of the package. Instead of the plastic film, it is also possible to use a sheet similar to the sheet of paper (
2
) which has a specific permeability or a sheet of paper coated with a sealing product such as a layer of extruded polyethylene or of poly(vinyl acetate). In the case of a blister pack, a flexible plastic film, thermoformed to the shape of the device to be packaged, is used.
The sheet of paper (
2
) has a specific permeability which makes it a barrier to microorganisms but which allows the sterilizing agents to pass through it so as to sterilize the closed package and its contents by sterilization methods using, as sterilizing agents, steam or sterilizing gases such as ethylene oxide. The package may also be sterilized by ionizing radiation, such as gamma or beta rays.
Advantageously, these packages offer the possibility of individually packaging the articles and of being opened, if necessary, only at the moment the sterilized article is used. They therefore allow the sterilized articles to be stored under proper sterility conditions.
In more detail, the sheet of paper (
2
) that can be used to form these packages is obtained via a wet route using a paper process by dewatering an aqueous suspension of cellulose fibres which generally includes a wet-strength agent. In addition, a cohesion agent may be introduced either throughout the aqueous suspension of fibres or by a surface treatment of the wet sheet, in order to mechanically strengthen the sheet. Moreover, a sizing agent may also be introduced either throughout the aqueous suspension of fibres or by a surface treatment of the wet sheet, so as to reduce the absorption of water by the sheet. Next, the sheet is dried.
This sheet may be coated on one of its sides, uniformly, with a continuous layer, or in patterns, especially patterns of grids or zones, with a heat-and/or pressure-sealing adhesive. It is then sealed against a plastic film or another sheet of paper acting as a barrier to microorganisms, over a certain perimeter depending on the desired shape of the package, while leaving an opening. In some cases, the sheet of paper is not coated with such an adhesive since, because its composition includes a compound having heat-sealing properties, such as starch for example, or else a thermoplastic polymer which is in the form of fibres or is introduced in the form of a stable aqueous emulsion (latex), it may be heat-sealed directly against a thermoplastic film. The packages are cut to the suitable shape and size.
The specific permeability of these sheets of paper is obtained by the choice of cellulose pulps, generally comprising between 0 and 70% by weight of short fibres and the balance to 100, of long fibres, of their refining (unrefined to a refining of 40 degrees Schoepper-Riegler) and by adjustments to the paper machine that are known to those skilled in the art. The entanglement of fibres of the sheet allows there to be a compromise between the porosity of the sheet and the diameter of the pores which creates this necessary specific permeability and a tortuous path in order not to let the molecules of water vapour or of sterilizing gases to penetrate without letting them pass over the dust particles carrying bacteria or other microorganisms. In the field of sealable sterilizing packages, it is recommended that a mean equivalent pore diameter not exceed 35 &mgr;m and no individual diameter value exceed 50 &mgr;m, according to the BS 3321:1986 standard.
British Patent Application GB 1,559,843 has described a sterilizing bag formed on one side from an impermeable thermoplastic film (
1
) and on the other side by a sheet of paper/impermeable thermoplastic film complex (
3
) sealed to a sheet of paper (
2
) acting as a barrier to bacteria and being permeable to the sterilizing agents (gases or steam), the complex being shorter in length than the other constituents so that the sterilizing agents can penetrate that region of the sheet (
2
) which remains permeable. The purpose of the construction of this package is to protect the sterilized articles when opening the bag. In particular, it prevents particles which could be pulled out the sheet of paper (
2
) when opening the package from being deposited on the articles. However, it has the drawback that its manufacture is not very practical since it requires having to join sheets of different length together and the sterilizing agents can penetrate only a small region, a situation which may be prejudicial to proper sterilization.
Moreover, sheets for sealable sterilizing packages are known which are based only on cellulose fibres (no synthetic fibres) and are manufactured and sold by Arjo Wiggins under the trademarks ETHYPEL® and PROPYPEL® in Europe. These sheets form a high bacterial barrier but have a mechanical strength which may prove to be insufficient, even if they are surface treated with a strengthening agent such as starch, polyvinyl alcohol or an acrylic latex, when it is desired to package heavy or sharp articles.
Paper sheets reinforced by synthetic fibres mixed with the cellulose fibres have therefore been proposed. For example, such sheets comprising polyester synthetic fibres are sold by Argo Wiggins under the trademark STERISHEET® in Europe. For an equivalent grammage, these so-called reinforced sheets have a higher mechanical strength than purely cellulosic sheets but, on the other hand, their bacterial barrier is slightly lower.
Other sterilizing packaging sheets have also been proposed which are sheets of nonwovens obtained by a dry route and comprising only hot-bonded synthetic fibres. For example, such sheets made of polyethylene fibres are sold by DuPont de Nemours under the trademark TYVEK®. These sheets have a high mechanical strength. However, one drawback with these sheets is that their look-through is very heterogeneous, that is to say the distribution of the fibres is very irregular and therefore the permeability of the sheet is not uniform. Thus, at certain points, the sheet may have pores too large in diameter. These purely synthetic sheets also have the drawback of having extremely long biodegradability times. Moreover, they are more expensive.
What is therefore sought is a sterilizing packaging sheet which has simultaneously and necessarily several properties.
One of the properties is that the sheet must be tear resistant. Th
Herve Philippe
Paris-Jolly Agnes
Bacon & Thomas
Jastrzab Krisanne
Wiggins Arjo
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