IN-LINE RADIATION STERILIZATION FOR WOUND DRESSINGS

Abstract

The present invention relates to an in-line method of radio sterilization of wound dressings using electrons. A packaged wound dressing is provided by means of a production apparatus and conveyed to a sterilization module by means of a conveying device. The packaged wound dressing is sterilized by means of a sterilization module coupled in-line to the production apparatus. The sterilization module comprises an electron beam source, which generates electrons having an energy of between 150 keV and 350 keV. The energy dose to which the packaged wound dressings are exposed is at least 15 kGy and no more than 30 kGy. The conveying device moves the packaged wound dressings at a speed of at least 10 m/min and no more than 200 m/min.

Claims

1. A method of in-line sterilization of a packaged wound dressing, comprising the following steps: providing a packaged wound dressing by means of a production apparatus (10, 20), conveying the packaged wound dressing by means of a conveying device to a sterilization module (50), sterilizing the packaged wound dressing by means of at least one electron beam source (51) present in the sterilization module (50), wherein the sterilization module (50) is coupled in-line to the production apparatus (10, 20), a) and wherein the energy dose to which the packaged wound dressings are exposed is at least 15 kGy and no more than 30 kGy, b) and wherein the energy of the electron radiation is between 150 keV and 350 keV, c) and wherein the conveying device moves the packaged wound dressings at a speed of at least 10 m/min and no more than 200 min/m.

2. The method of claim 1, wherein there is a plurality of packaged wound dressings which are conveyed in packagings that are connected to one another at their ends to the sterilization module (50) and in that the wound dressing packagings that are connected to one another at their ends are cut to size into individually packaged wound dressings post sterilization.

3. The method of claim 1, wherein there is a plurality of packagings that are connected to one another at their ends and are cut to size into individually packaged wound dressings prior to the sterilization and the individually packaged wound dressings are conveyed to the sterilization module (50).

4. The method of claim 3, wherein the individually packaged wound dressings are held on the conveying device by means of negative pressure.

5. The method of claim 3, wherein the individually packaged wound dressings are held on the conveying device by means of pockets which are sealed or partially opened.

6. The method a of claim 1, wherein the sterilization module (50) has a self-shielding configuration by virtue of the shielding being brought about by components of the sterilization module (50).

7. The method a of claim 1, wherein the conveying device is controlled by a programmable logic controller through open-loop and/or closed-loop mechanisms.

8. The method of claim 1, wherein the wound dressing has a height of from about 0.5 mm to about 10.0 mm.

9. The method of claim 1, wherein the packaged wound dressing has a mean grammage of between from about 0.2 kg/m2 kg/m2 to about 0.5 kg/m2 kg/m2.

10. The method of claim 1, wherein the packaging of the packaged wound dressing is a peel pouch consisting of a first sterile barrier (201) and a second sterile barrier (202), wherein the first sterile barrier (201) is connected to the second sterile barrier (202) by way of an adhering outer region (203) so as to form an internal cavity for accommodating the wound dressing.

Description

FIGURES

[0059] To better understand the present invention and its advantages, reference is now made to the following embodiments in conjunction with the associated figures.

[0060] FIG. 1

[0061] Island dressings in connected peel pouches.

[0062] FIG. 2

[0063] Schematic structure of an embodiment of the apparatus for producing a sterilized, packaged wound dressing.

[0064] FIGS. 3, 4, 5

[0065] Measured values at an acceleration voltage of 200 keV, 250 keV and 280 keV.

[0066] FIG. 6

[0067] Calculated DUR for the acceleration voltages of 200 keV, 250 keV and 280 keV.

[0068] FIG. 1 shows a cross section (not true to scale) through a chain of packaged wound dressings 200. The wound dressing 210 is enclosed by a first material ply 201 and a second material ply 202. The first material ply 201 and the second material ply 202 are connected by means of a seal 203 such that the first material ply 201 and the second material ply 202 form a sealed packaging pouch containing the wound dressing 220. An individual packaged wound dressing 210 is connected to a respective further packaged wound dressing at the seal 203 on respective opposite sides of the packaging pouch. The first material ply 201 and the second material ply 202 extend over the entire length of all packaged wound dressings 200. Together, all packaged wound dressings form a pouch chain 200.

[0069] The first material ply 201 consists of a transparent film and the second material ply 202 consists of paper.

[0070] The wound dressing 210 comprises an absorbent ply 223. The absorbent ply 223 is situated between the covering layer 224 and the wound contact layer 222. The wound contact layer 222 is completely covered by a backing paper 221. For instance, the covering layer 224 consists of a polyurethane film. The wound contact layer 222, which may have a smaller area than the covering layer 224, may be formed from, for example, a hydrophilic nonwoven material or a perforated polyurethane film coated with an adhesive silicone.

[0071] The connected pouch chain is moved in direction 230x by means of a conveying device. The directions 230y and 230z are defined perpendicular to 230x and perpendicular to one another. The direction 230y is aligned along the width of the wound dressing and the direction 230z is aligned along the height of the wound dressing.

[0072] In the example shown, the wound dressing with the packaging has a maximum height 231 of 2 mm. The length 232 of the packaged wound dressing is 12 cm in this example. The individual, packaged wound dressing 210 is 8 cm wide. The unpackaged wound dressing has a width of 5 cm and a length of 7 cm. The first material ply 201 and the second material ply 202 are 8 cm wide.

[0073] The length of the wound dressing is defined orthogonal to the direction 230x and the width of the wound dressing is defined along 230x.

[0074] FIG. 2 shows the schematic structure of an apparatus 100 for producing a sterilized, packaged wound dressing. The wound dressing is produced in the production module 10. A conveying device (not shown here) is used to convey the wound dressings to the packaging machine 20, where they are packaged or sealed, with the packaging forming a germ barrier.

[0075] The wound dressings are now available in a connected pouch chain as shown in FIG. 1. The connected pouch chain is guided to the sterilization module 50 and, in the latter, guided by the rollers 52b, 52c, 52d, 52e to the electron beam source, which is the electron accelerator 51 in this case. The rollers 52b and 52e are both parts of the shielding device and parts of the conveying device.

[0076] The pouch chain is deflected out of the plane B by means of a first roller 52b and then runs in the plane BC. The plane B is defined by the pouch chain entering the sterilization module. The pouch chain runs in the plane BC between the first roller 52b and the second roller 52c. The pouch chain is steered into the region of the electron beam source 51 of the sterilization module 50 by means of the second roller 52c and the third roller 52d and runs in the plane CD. The packaged wound dressings in the pouch chain are sterilized by means of the radiation emanating from the electron beam source 51. After leaving the sterilization module 50, the fourth roller 52e steers the pouch chain into the plane E from the plane DE specified by the alignment of the pouch chain between the third roller 52d and the fourth roller 52e. The first and the fourth roller 52b, 52e are used as component parts of the shielding device.

[0077] A further shielding is provided by means of the shielding device 52a. The shielding device 52a consists of lead elements 54 mm thick. After the pouch chain has left the sterilization module 50, it is steered to the cutting-to-size module 30. The cutting-to-size module 30 cuts the 20 connected pouch chain into individual, packaged wound dressings.

[0078] In the embodiment of a sterilization module 50 shown in FIG. 2, wound dressings with a maximum height of 2 mm are irradiated. The conveying device speed is 200 m/min. The electron acceleration voltage applied is 250 keV. The power of the electron beam source 51 is 25 6.9 kW, and the current intensity of the electron beam is 27.6 mA. The target value for the energy dose absorbed by the wound dressing is 25 kGy.

[0079] The sterilization module 50, depicted only by way of example and for the purpose of illustrating a possible embodiment in FIG. 2, can have a deviating structure within the scope of the 30 present invention. Likewise, the irradiation of the wound dressings to be sterilized can be performed with different parameters within the scope of the ranges proposed according to the invention. In this respect, the embodiment shown in FIG. 2 represents only one variant identified as advantageous by the inventors of the present invention.

[0080] The measured values reproduced in FIGS. 3 to 5 were recorded using the method described below.

[0081] Respectively 2 dosimeters are applied to the front and back exterior of the packaging. The measured values of these dosimeters 1, 2, 3, 4 are not included in the DUR calculation. 1 and 2 are fastened to the front exterior, and 3 and 4 are fastened to the back exterior.

Dosimeters

[0082] 5,6 and 7 are fastened to the inside of the packaging, between the front exterior of the packaging and the wound dressing. Dosimeters 8 and 9 are introduced into the packaging and into the wound dressing itself. Dosimeter 10 is fastened between the back exterior of the packaging and the wound dressing.

[0083] The packaged wound dressing is irradiated from one side. The electron radiation is incident first on the front exterior where dosimeters 1 and 2 have been applied.

[0084] The measurements are performed for an acceleration voltage of the sterilization module u.sub.5of 200 keV and a current intensity of 5.6 mA, an acceleration voltage of 250 keV and a current intensity of 6.9 mA, and an acceleration voltage of 280 keV and a current intensity of 7.5 mA.

[0085] The target value for the energy dose absorbed by the wound dressing is 25 kGy.

[0086] The packaged wound dressing has a height of 2 mm.

[0087] The packaged wound dressing is now conveyed through the irradiation region of the sterilization module at a speed of v.sub.w=10 m/min by way of the conveying device.

[0088] 3 measurements are performed for each acceleration voltage.

[0089] To avoid backscatter, the packaged wound dressings are placed on a piece of paper 2 mm thick. The paper is situated on the side facing away from the electron beam source.

[0090] The measurement results for the acceleration voltage of 200 keV are shown in FIG. 3. The measurement results for the acceleration voltage of 250 keV are depicted in FIG. 4, and the measurement results for the acceleration voltage of 280 keV can be found in FIG. 5.

[0091] The DUR for all acceleration voltages is calculated in FIG. 6. The highest energy dose and thelowestenergydoseisselectedforeachaccelerationvoltagefromallmeasurementsbelonging to dosimeters 5 to 10. Then, the highest energy dose is divided by the lowest energy dose in order to obtain the DUR value.

[0092] A DUR of 3.83 emerges for the acceleration voltage of 200 keV. The irradiation is more uniform for the acceleration voltage of 280 keV. The DUR isat1.39 for the acceleration voltage of 280 keV. The irradiation is most uniform for the acceleration voltage of 250 keV.

[0093] The DUR is 1.33 for the acceleration voltage of 250 keV.

[0094] It was found that an acceleration voltage of 250 keV is particularly suitable.