MXPA00004659A - Sterilization wrap and procedures - Google Patents

Abstract

A sterilization device comprising an inner sterilization wrap and a re-usable outer sterilization bag. The re-usable outer sterilization bag has an outside surface and an inside surface defining a pouch with an opening for receiving the inner sterilization wrap and a sterilizable object. The material is preferably a spunbonded or meltblown polyolefin fiber non-woven breathable web. Also provided are methods of sterilizing an object, and methods of using a sterilizable bag.

Description

Field t ll lBY «nsÍFa This invention relates in general to the field of materials suitable for sterilization and which contain objects, typically for use in the medical industry.

An eceden »4e the Ipvencjon Sterilization of medical equipment and supplies is vital to minimize the spread of harmful or infectious agents to patients. Medical equipment or supplies in need of sterilization include, for example, clamps, scalpel scalpel handles, retractors, forceps, scissors, basins or towels. Typically, the object to be sterilized is placed in an instrument tray and packaged in at least one layer of sterilization wrap. The wrapped object is then sterilized within the sterilization casing through a variety of methods, for example, autoclave steam, plasma sterilization, microwave irradiation, etc. The object sterility is typically maintained by the Keep the packaging of the sterilization wrap sealed until immediately before use.

In the field of sterilization casings, many designs have been provided which attempt to allow the penetration of a sterilizer therethrough, while the subsequent entry of any contaminant is minimized. The type of sterilization technique used can dictate the materials used. For example, where gamma radiation or other radiation is used to sterilize the contents, sterilization wrapping can be sealed and even made impermeable to gases. However, when plasma sterilization, steam, ethylene oxide, other attenuating gases are used, to sterilize an article, the sterilization envelope must be permeable or have the capacity to breathe. This presents a challenge to build a breathable wrapper that minimizes the entry of any contaminants, for example, bacteria, after the sterilization procedure.

Many sterilization casings of the previous art require a permanent sealing of the sterilization casing around the object to be sterilized. Therefore, to be able to access and use the sterilized object these sterilization wraps of the prior art had to be torn to open them. In addition, the sterilization wraps of the prior art are typically sheets which are wrapped in position and secured with adhesive tape or some other adhesive securing means. An alternate method will be to provide an external sterilization wrap that maintains the wrapped conformation of the inner wrapper. These and other objects of the invention will be apparent to those skilled in the art.

Synthesis of the Invention The present invention provides a sterilization device comprising an inner sterilization envelope and an external and recyclable sterilization bag. The recyclable external sterilization bag has an outer surface and an inner surface defining a bag with an opening to receive the inner sterilization envelope the sterilizable object. The material is preferably a breathable non-woven fabric of polyolefin fiber melt blown or spin bonded. The present invention also provides methods for sterilizing an object, and methods for using a sterilization bag.

Detailed description of the invention As used herein the term "sterilization" refers to a wide variety of techniques employed to attenuate killing or eliminating infectious agents. For example, sterilization contemplates gas plasma sterilization, as described in U.S. Patent No. 4,801,427, in addition to steam sterilization, sterilization with ethylene oxide and irradiation.

As used herein the term "polymer generally includes stoppage is not limited to, homopolymers, copolymers (such as, for example, block copolymers, random grafting and alternating), terpolymers etc. and mixtures and modifications thereof. Furthermore, unless specifically limited, the term "polymer" includes all possible geometric configurations of the material. These configurations include, but are not limited to, isotactic, syndiotactic and random symmetries.

As used herein, the term "microfibers" means small diameter fibers having an average diameter no greater than about 75 microns, for example, having an average diameter of about 0.5 microns around 50 microns, or more particularly, microfibers. they can have an average diameter of around 2 microns around 40 microns.

As used herein the term "knitted fabric or fabric" means a fabric having a single fiber structure or yarns which are internally deposited but not in an identifiable manner as in a knitted fabric. Fabrics or non-woven fabrics have been formed by many processes such as, for example, meltblowing processes, spinning processes, and carded and bonded weaving processes.

As used herein the term "spunbonded fibers" refers to small diameter fibers which are formed by extruding the molten thermoplastic polymer material as filaments of a plurality of thin capillary tubes, usually circular from a spun organ with the diameter of the exorbitant filaments is then rapidly reduced as indicated for example, in United States of America No. 4,340,563 granted to Appel others, and in United States of America No. 3,692,618 issued to Dorschner et al. , in the patent of the United States of America No. 3,802,817 granted to Matsu and others, in the patent of the United States of America N 3,338,992 granted to Kinney, in the United States of America Patents No. 3,502,763 and in the No. .3, 909, 009 granted Levy, and in the United States of America Patent No. 3,542,615 granted to Dobo and others. Spunbonded fibers are generally continuous and larger than 7 micron more particularly, have an average diameter greater than microns.

As used herein the term "blown fibers" means the fibers formed by extruding a molten thermoplastic polymer through a plurality of fine, usually circular, capillary yarns as filament yarns fused into a gas stream ( for example air) at high speed which attenuates the filaments of molten thermoplastic polymer material to reduce s diameter, which can be to a microfiber diameter. The molten fibers are then transported by a high velocity gas stream and deposited on a collector surface to form a randomly dispersed fused fiber fabric. The process is described, for example, in the patent of the United States of America No. 3,849,241 and in the patent of the United States of America No. 3,978,185.

The meltblowing process generally uses an extruder to deliver the molten polymer to a matrix pourer wherein the polymer is fibrillated as it passes through the fine openings, forming a curtain of filaments. The filaments are pneumatically pulled and deposited on a moving foraminous mat, a strip or a wire former to form the non-woven fabric.The non-woven fabrics can be measured in ounces per square yard (osy) or in grams per meter. square (gsm). (Multiply ounces per square yard by 33.9 grams per square meter).

The fibers produced in the co-melt blowing process are generally in the range of about 0. microns in diameter to about 10 microns in diameter depending on the conditions of the processes and the desired fine use for the fabrics to be produced. With such fibers Changes in the temperature of the cooling fluid and the pneumatic drag pressure can also affect the diameter of the fiber. The finer fibers are generally more desirable since they usually produce greater barrier properties in the fabric within which they are manufactured.

The fabric of this invention can be used in a single layer incorporation or as a multiple layer laminate incorporating the fabric of this invention. Such a laminate can be formed by a number of different techniques including but not limiting the use of adhesive, needle piercing, ultrasonic bonding, bonding with printing, thermal calendering and any other method known in the art. Such a multilayer laminate may be an incorporation where some of the layers are meltblown and some are bonded with yarn such as a laminate (SM) bonded with co-melt spin / blow or a laminate (SMS) bonded with spin / blow co-melting / spinning, as described in United States of America Patent No. 4,041,203 granted to Brock et al. and in United States of America Patent No. 5,169,706 issued to Collier et al. or where some of the layers are made of basic fibers. The fibers used in the other layers can be polyethylene, polypropylene or bicomponent fibers. A useful source of such SMS laminates bonded with spinning / meltblowing / spunbonding is commercially available from the Kimberly-Clark Corporation as a KIMGUARD sterilization wrapper. " A SMS laminate bonded with spinning / meltblowing / spinning, for example, can be manufactured by sequentially depositing on a moving conveyor belt or on a forming wire a layer of spin-linked fabric, then a layer of meltblown fabric and finally another layer linked with spinning and then joining the laminate in a manner described above. Alternatively, the three layers of fabric can be manufactured individually, collected in rolls and combined in a separate joining step.

In repeated use applications, when the fabric of this invention is an SMS laminate bonded with spunbond / meltblown / spunbond, it has been found advantageous to pre-bond one of the spunbond layers. The premix is a step of joining (thermally) a layer by itself using a pattern of 8% to 50% bond area or more particularly around 25% bond area with many small pins. In these situations, the pre-bond is advantageous with polyolefin fabrics due to the relatively high heat of fusion and the low melting point of the polyolefin. It is believed that in order to supply sufficient heat for a polyolefin fabric to be bonded, the addition of heat must be made sufficiently slow to avoid excessive melting of the fabric and to stick to the calendering rolls. The previous joining of one of the layers linked with spinning helps to reduce the intensity of the temperature at which the laminate must be fastened in the joining step.

Pre-bonding also provides the material with greater abrasion resistance although it may reduce dispersibility in some. Since it is an object of this invention that the material provide good barrier properties and thus be smooth and easily foldable, the pre-bond should be kept to a minimum. The previous union is optional and if desired it should be restricted to one layer only for this reason.

After pre-bonding, the spin-bonded layer can then be combined with meltblown unbonded layers and spunbond and bonded with an open bonding pattern as mentioned above, preferably with a pattern having relatively longer pins. The bonding temperature may vary depending on the exact polymers involved, the degree and bond strength desired and the final use of the fabric.

The layers of the fabric of this invention may also contain fire retardants for safety against fire or pigments to give each layer the same different colors. Fire retardants and pigments for thermoplastic polymers bonded with co-melt spinning and blowing are known in the art and are usually internal additives. A pigment, if used, will generally be present in an amount of less than 5% by weight of the spunbonded / meltblown / spunbonded bonding compound.

The material of this invention may also have topical treatments applied to it for more specialized functions. Such topical treatments and their methods of application are known in the art and include, for example, alcohol repellent treatments, similar antistatic treatments, applied by spraying, by means of immersion, etc. An example of such topical treatment is the application of ZELEC® antistatic mixed and neutralized alkyl phosphates (available from E.I. DuPont, of ilmington, Delaware.) The present invention provides a sterilization device comprising an inner sterilization wrap and a reusable outer sterilization bag. The reusable external sterilization bag has an outer surface and an inner surface defining a bag with an opening for receiving the inner sterilization wrap and the sterilizable object. In one embodiment, the bag can be formed from a single sheet of non-woven material permeable to g or capable of breathing.

As used herein, the term "breathable" refers to the material which is permeable to water vapor having a water vapor transmission rate (minimum VTR of about 300 grams per square meter per 2 hours, calculated in accordance with ASTM E96-80.

In preferred embodiments, a commonly available sterilization indicator can be placed within a sterilization bag for easy determination of the sterilization status of the contents thereof.

The present invention provides at least about 85% bacterial filtration efficiency to a sterilizable object. More preferably, the present invention provides at least about 90% efficiency of bacterial filtration to the sterilizable object, and more preferably at least about 95% efficiency of bacterial filtration to the sterilizable object.

The invention provides that the material of the sterilization bag can be constructed of polyolefin. And preferred embodiments, the outer bag material and / or the inner sterilization wrap may preferably be an SMS laminate bonded with spinning / meltblowing / spin bonding, which may be electrostaticized as described for example in the United States patent. United of America No 5,401,446. Electretization involves exposing the material to a pair of electric fields that have opposite polarities. Cad electric field forms a discharge corona which is imparted by the material. Other means of electretizing the material are known, such as thermal, contact with liquid and electron beam methods.

In preferred embodiments, the material of the sterilization bag comprises a blown layer with fusing between the first and second layers bonded with spinning. Preferably, the material is between about 0.6 and ounces per square yard. The invention provides that the spin bonded layer can be between about 0.25 and 2. ounces per square yard and the meltblown layer can be between about 0.1 and 2.0 ounces per square yard. Most preferably, the material is about 2.2 ounces per square yard, such that the layers bonded with yarn are about 0.85 ounces per square yard and the blown cap with melting is about 0.5 ounces per square yard.

The sterilization bag can be formed from a sheet of material folded once and ultrasonically sealed laterally or by other means, such as heat sealing by stitching or adhesion, to define a bag with or opening to receive therein a sterilizable object. construction and the shape of the sterilization bag can vary greatly depending on the projected size of the objects to be sterilized which must be inserted into it. For example, one end of the folded materi may be longer in order to provide a single foldable to selectively cover the opening of the bag. The sterilization bag is designed to be reused, therefore, the construction must allow the placing and removal of sterilizable objects without destroying the bacterial filtration integrity of the bag.

The invention further provides methods for sterilizing an object, methods for using an external sterilization bag, comprising, first placing an objective inside the sterilization wrap within an external sterilization bag for reuse. The external sterilization bag for reuse has an outer surface and an inner surface defining a bag with an opening inside for receiving the inner sterilization wrap and the sterilizable object. The external sterilization bag is made of a nonwoven material with breathing capacity. The external sterilization bag containing the inner sterilization envelope, and containing the object, and then sterilized by the available means.

Several patents have been described here, which are therefore incorporated by reference in their entirety. The present invention is intended to be demonstrated, but not limited, by the following examples.

EXAMPLES The following test procedure was carried out to determine the efficiency of bacterial filtration (BFE) of various filtration materials, using a bacterial challenge count rate to collect effluent count samples, to determine the filtration efficiency percentage. bacterial (% BFE). This procedure provides a more severe count for most filtration materials than is normally expected in normal use. This test procedure allowed a reproducible bacterial challenge to be supplied to the test materials.

The bacterial filtration efficiency test BF described below was carried out by Nelson Laboratories (SALT Lak City, UT). The sterilization was carried out in a STERRAD * gas plasma sterilization unit available from Advance Sterilization Products, a division of Johnson & Johnson Medical, Inc. (Irvine, CA). Test Procedure A culture of Staphylococcus aureus was diluted with 1.5% peptone water at a precise concentration for challenge levels of counts of 2200 ± 500 units of colony formation (CFU) per test sample. The suspension of bacterial culture was pumped through a nebulized "Chicago" at a controlled flow rate and at a fixed air pressure. The constant challenge release, at a fixed air pressure, formed aerosol droplets with a median particle size (MPS) of approximately 3.0 um. The aerosol droplets were generated in a glass aerosol chamber and were pulled through an Andersen sampler of viable particle, of six stages, for harvesting. The collection flow rate through the test sample and the Andersen sampler was maintained at 28.3 LPM (1 CFM). The test controls and the test samples were challenged for a period of two minutes.

The challenge release rate also produces a consistent challenge level of 2200 ± 500 CFU in the control dish. A control test (without filtering means in the air stream) and the reference material are included after test samples 7-10. The Andersen sampling, a sieve sampler, hits the aerosol droplets on six test plates. agar based on the size of each drop. The agar medium used was soybean casein digestive agar (SCDA). The agar plates were incubated at 37 &C ± 2 »C for 48 ± 3 hor and the colonies formed by each drop of aerosol laden with bacteria were counted and converted to values of "a probable goal" used to determine the level of promed challenge released to the test samples. The distribution rate colonies for each of the six agar dishes was used to calculate the mean particle size (MPS) of the aerosol challenge.

The filtration efficiencies were calculated as a percentage difference between the test sample runs and the average control using the following equation: C-T BFE% = X 100 Where: C = Average of control values T = Total count for the test material This test procedure produces a more severe challenge for most filtration materials than might be expected in normal use. The purpose of this procedure is not to optimize the efficiency of filtration, but to measure consistently, as accurately as possible, the differences between the materials differences in the same material over time.

Several quality control steps have been taken to consistently perform the bacterial filtration efficiency procedure. First, the average test control, determined by control runs where no filter media is in the air stream, should be maintained at 2200 ± 500 CFU for the test to be valid. Additionally, at least one reference material included with every 7-10 samples tested. The statistical evaluation of these reference material data were recorded in control charts. The reference material should be within the upper and lower control limits (± 3 standard deviations) established for the test.

The external sterilization bags used aq were made of a nonwoven composite layer material. material was about 2.2 ounces per square yard (bonding with spinning / blowing with melting / linking with yarn (SMS) Both layers linked with yarn have a basis weight 0. 85 ounces per square yard, and the melt blown layer has a basis weight of 0.50 ounces per square yard (see United States Patent No. 4,041,203 issued to Bro et al.). The invention contemplates that other weights may be used as well as other barrier materials for making bag. The material was manufactured in a bag by folding the sheet in half and ultrasonically sealing the two opposing sheets, thus leaving a single opening.

The internal sterilization casings used here were also made of a composite layer material bonded with spinning / blowing with fusion / bonded with woven SMS yarn. Spunbond / meltblown / spunbonded materials bonded with nonwoven SMS yarn from inner sterilization casings used here are commercially known as KIMGUARD sterilization casings, and were tested with (Table I) and without the (Table II) antistatic ZELEC * .

The electretization of materials was carried out as described in U.S. Patent No. 5,401,446. Typical conditions were around 68.9SF and 61% RH. The upper electrode was around d 15.0 KV kilovolt and the electrode polarization of about 0.0 KV kilovolt for the first set of electrodes and d about 18.0 KV kilovolt for the upper electrode and d about 0.0 KV kilovolt for the polarization of the electrode for the second set of electrodes. The temperature varied from about 68.83F to 70.22F, and the% relative humidity d around 40.0% to 63.0%. The upper electrodes varied d around 18 KV kilovolts to 10 KV kilovolts and the electrode polarizations were approximately constant Each used bag was exposed to a full gas plasma sterilization procedure at least six times before being used in the test described here. There was no apparent damage to the bag as noted by a visual inspection and FESEM inspection (scanning electron microscope emission field) of the fibers.

TABLE I Spunbonded / meltblown material with fusion / bound oon spun yarn for sterilization wraps and sterilization bags without surface treatment.

Each sample provided eleven analyzes to give a confidence level of 98% for the statistical analysis. The data suggest that the electrostatic coating of the sterilization had a greater effect on the filtration efficiency of BFE bacteria. However, the electretizing sterilization bag n had no effect on BFE bacterial filtration efficiency. Therefore, the results show that when using materials not treated with antistatic, the optimal combination for bacterial filtration efficiency BFE is a bag d non-sterilized sterilization with an electretized sterilization casing.

TABLE XI Super icie of inner wrap material bonded with spun / blown / melted yarn / linked with SMS yarn treated or unsightly 2ELEC » Once again, each sample provided onc analysis to give a confidence level of 98% for the statistical analysis. Therefore, these data suggest that an electretized sterilization wrapper has a considerable effect on bacterial filtration efficiency BFE. Surprisingly, in this example, when using inner wrap materials treated with antistatic, a sterilized electretized bag and combination with an electrically sterilized wrap showed a statistical improvement in filtration efficiency over a non-electrostatic sterilization bag.

Although the invention has been described in detail with respect to the specific incorporations thereof, it may be appreciated by those with a skill in the art that the alterations of these incorporations can easily be conceived. Therefore, the scope of the present invention should be evaluated as that of the appended claims and of any equivalents thereof.

Claims (20)

1. A sterilization device comprising: an inner sterilization wrap; and a reusable outer sterilization bag comprising an outer surface and an inner surface defining a bag with an opening for receiving the inner sterilization wrap and a sterilizable object, wherein the bag is made of a non-woven material, capable of breathe

2. The device as claimed in clause 1, characterized in that it also comprises a tray d sterilization substantially enclosed by the inner wrapper.

3. The device as claimed in clause 1, characterized in that it also comprises an antistatic treatment in the internal sterilization casing or in the external sterilization bag.

4. The device as claimed in clause 1, characterized by the external bag is electretized.

5. The device as claimed in clause 1, characterized in that the internal envelope is electretized.

6. The device as claimed in clause 1, characterized in that the inner casing and the outer bag are electretized.

7. The device as claimed in clause 1, characterized in that it is capable of providing at least about 85% filtration efficiency bacteria for the sterilizable object.

8. The device as claimed in clause 1, characterized in that it is capable of providing at least about 90% filtration efficiency bacteria for the sterilizable object.

9. The device as claimed in clause 1, characterized in that it is capable of providing at least about 95% filtration efficiency bacteria for the sterilizable object.

10. The bag as claimed in clause 1, characterized in that the material is polyolefin.

11. The bag as claimed in clause 10, characterized in that the material comprises a blown cap with fusion between the first and second layers linked with spinning.

12. The bag as claimed in clause 11, characterized in that the material is between 0.6 and 6 ounces per square yard.

13. The bag as claimed in clause 12, characterized in that the layers bonded with hilad are between about 0.25 and 2.0 ounces per square yard, the meltblown layers are between about 0.1 and 2. ounces per square yard.

14. The bag as claimed in Clause 11, characterized in that the material is about 2.2 oz per square yard.

15. The bag as claimed in clause 14, characterized in that the layers bonded with yarn are about 0.85 ounces per square yard and the blown cap with melting is about 0.5 ounces per square yard.

16. The bag as claimed in clause 1, characterized in that the bag is formed of a sheet of material folded and sealed laterally in ultrasonic form.

17. A method for using a sterilization bag comprising: » a) placing a sterilizable object inside an internal sterilization envelope; b) introducing the object into the sterilization wrap within an external sterilization bag for repeated use, said bag comprising an external surface and an internal surface defining a bolster with an opening for receiving the inner sterilization wrap and the sterilizable object, wherein the bag is made of a non-woven material capable of breathing; Y c) the sterilizable object.

18. The method as claimed in clause 17, characterized in that the inner wrapper and / or the outer bag are electretized and further comprises antistatic treatment in the inner sterilization wrap and / or in the external sterilization bag.

19. The method as claimed in clause 17, characterized in that the external sterilization bag provides at least about 85% bacterial filtration efficiency to the sterilizable object.

20. The bag as claimed in clause 17, characterized in that the material comprises a blown ca with polyolefin melting between the first and second layers of polyolefin bonded with spinning, where the cap bonded with yarn are between about 0.25 and 2.0 Oz per square yard and the melt blown layer is around 0.1 and 2.0 ounces per square yard. Ba ss S-ÚS-l-SnS A sterilization device comprising an internal sterilization envelope and an external sterilization bag for repeated use. The extern sterilization bag for repeated use has an outer surface and an internal surface defining a bag with an opening for receiving an internal sterilization wrap and a sterilizable objective. The material is preferably a co-breathable non-woven fabric of polyolefin fibers bonded with spinning or meltblowing. Also provided are methods for sterilizing an object, and methods for using a sterilizable bag.