Guide to Sterilization Pouches in Sterile Processing

What is a sterilization pouch and how is it used?

A sterilization pouch, or peel pack, is a disposable package used in a sterilizer to allow penetration of the sterilant to the items placed inside. After sterilization, these Class II Medical Devices maintain the sterility of the processed item.

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A well-designed and correctly used sterilization pouch allows for effective sterilization, safe handling, and storage of all pouched items until needed for use. In addition to protecting items through this process, they also facilitate proper aseptic presentation of devices in an operating room. Much like the instruments they protect, sterilization pouches used in hospitals are also medical devices. Therefore, they require clearance by the Food and Drug Administration (FDA) and validation for use in specific sterilizers and cycles.

Sterilization pouches come in three designs:

1. Self-seal pouches have an opening with an adhesive strip on one end. Items are placed into the pouch prior to sealing the open end with the adhesive strip.
2. Heat-seal pouches have an opening on one end. Items are placed into the pouch prior to sealing the open end using a heat sealer.
3. Rolls or tubing can be cut to the desired length and are open on both ends. Technicians will heat seal one end, place items into the pouch, and then heat seal the other end.

What are sterilization pouches made of?

There are two types of combination peel pouches:

• Paper/plastic – These pouches are for use in Steam or Ethylene Oxide (EO) sterilization
• Tyvek/plastic – These pouches are for use in Vaporized Hydrogen Peroxide (VHP) and EO sterilization.

A sterilization pouch consists of two main parts: medical grade paper, or Tyvek®, and a clear plastic film, held together by heat seal or with an adhesive. These materials are specifically designed to allow penetration of chemicals, heat, vapor, or steam.

It's important to remember that paper pouches are used in steam, and Tyvek is used in Vaporized Hydrogen Peroxide (VH2O2) sterilization, such as in V-PRO Low Temperature Sterilizers. Although they may look similar, when a pouch is used in the wrong sterilization process, a failure is likely to occur. Tyvek placed in steam will melt at higher temperatures. Paper placed in VH2O2 will absorb the sterilant vapors, which can hinder the sterilant from reaching the device. As well, paper that has absorbed VH2O2 can potentially damage instruments and can possibly catch on fire.

What are proper sterilization packaging guidelines?

Peel pouches are used for lightweight, low-profile instruments or medical devices. Per ANSI/AAMI ST79, the pouch should be of the right size and strength to accommodate the item(s) being packaged. For example, using paper/plastic pouches for heavy metal instruments could result in sterility maintenance problems due to events such as inadequate drying or rips and tears during storage or handling.

Validation/Testing

As mentioned earlier, Sterilization Pouches are Class ll Medical devices designed to allow sterilant penetration into the pouch, as well as maintain sterility of the device inside the pouch after sterilization. To validate that the pouch meets these requirements, pouches undergo rigorous testing to confirm their performance.

One crucial and stringent test performed during validation is half-cycle sterilization testing. This testing is used to simulate medical devices under worst-case conditions and confirm microbicidal efficacy. This test requires highly resistant bacterial spores to be placed in a challenging location to sterilize, such as inside lumens. The device is then pouched and sterilized in a cycle programmed with half of the cycle’s exposure time. All of the viable bacterial spores must be eliminated at the end of the half-cycle for the test to be considered a success.

How do you use sterilization pouches in a sterilizer?

1. Choose the correct pouch for your sterilization modality: High Temperature or Low Temperature. As you choose your pouch, confirm the pouch materials are compatible with the medical devices to be packaged.
2. Confirm the pouch is validated. The pouch and the device you’re sterilizing need to not only be compatible but validated for the sterilization process. Check the Instructions for Use (IFU) of the pouch or confirm validation with the manufacturer.
3. Package Devices according to the IFU.
4. Place the Pouch in the Sterilizer. Pouches can be placed flat on a shelf or placed on their standing edge facing the same direction, alternating paper or Tyvek to plastic.

Can you reuse sterilization pouches?

Sterilization pouches are single-use disposable devices and should not be reused. Any defects, tears, or damage also means the pouch should be discarded and not used for sterilization.

Can you double pouch sterilization pouches?

While there are no AAMI or AORN guidelines that state you must double peel pouch items for use in the Operating Room (OR), some ORs request certain items be double pouched to aid in aseptic presentation. Examples include several small items or instruments that might present a challenge during aseptic presentation.

When a pouch is validated by the manufacturer for double pouching, it is still important to review the pouch instructions for use. Make sure to follow your facility's policies and procedures when deciding whether to double pouch.

Tips for Double Pouching:

• The inner and the outer pouch should be film to film, both facing the same direction
• The inner pack should not be folded over

How to Choose the Right Sterilization Pouch

Considerations when selecting a sterilization pouch:

• Keep in mind the proper sizing and application of pouches to allow for adequate air removal, sterilant penetration, and drying
• Keep 1" of space around the item being sealed from all sides of the pouch
• Fill a pouch to a maximum of 75% of its packing volume to allow for the sterilant to penetrate the pouch and for the pouch to conform to the air evacuation process during sterilization
• Refer to manufacturer’s Instructions for Use for proper sizing and use of sterilization pouches

Tyvek® is a registered trademark of DuPont.

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The Back Page: Taking it back 64 years

Originally published in Paper, Film and Foil Converter in March

Pouch Papers Keep Rolling to Greater Future

For packaging high-volume, mass distributed items economically, pouch materials are hard to beat. Close teamwork between converter, customer and package machine maker is essential to production of better packages and this expanding and increasingly diversified market.

A greater swing in pouch packaging may be expected in coming months as large volume packagers seek to economize. 

Renhe contains other products and information you need, so please check it out.

Depending on the size, type, distribution and merchandising of the product to be packaged, and honest adaptability to machine handling, the pouch is inherently an economical flexible package. It eliminates separate production operations.  Beginning with base flexible materials in rolls, packaging machines form, fill and seal pouches (or packets as they are also called) automatically. The result is savings in time and labor to the product manufacturer. A further saving is realized in the cost of roll stock compared with converted bags or other packaging media. 

Aware of the trend to expanding pouch packaging, Thilmany Pulp and Paper Co. has developed a line of polyethylene-coated papers that meet a variety of packaging needs.

In airing the subject at a seminar for distributors, Thilmany reviewed the various types of pouches and the requirements of good pouch papers.

There are four basic styles of pouches, all of which can be produced by automatic machines. They are:

• THE PILLOW POUCH: This is most commonly used and was the first to be developed for automatic packaging. It is still widely employed for packaging free-flowing solids such as soap and coffee. It has a center seam seal plus a head seal at both ends and is formed from a single sheet. Although it has the advantage of a large capacity, its disadvantage as a paper pouch is a weaker center seam because the bond on one side is made to an uncoated surface. This disadvantage, plus operating difficulties (such as friction) in producing it, prompted manufacturers to develop other types.
• THE 4-SEAL POUCH Is the second most commonly used style and is formed by combining two sheets. Obviously, this eliminates the weak seen problem with pouch papers because the coated surfaces of each sheet can be bonded. Its advantage of extreme strength is offset to some extent by its capacity limitations, making it suitable for packaging small items. It can, however, be adapted to packaging shaped solids (screws, washers, etc.) by using a horizontal rather than a vertical feed, and by changing the sealing mechanisms to eliminate the reciprocating operation and thus reduce friction. Another desirable quality for some uses is that the pouches need not be cut apart individually, but can be used in “tandem” or “strip” with serrations between for later cutting or tearing by the consumer.
• THE 3-SEAL POUCH is fed into the machine from a single roll and is folded over and sealed on the three “open” sides. Not too common, its most popular acceptance is in small sugar packs for individual servings. Actually, it is a variation of the pillow pouch with the center seam problem eliminated, but with a much smaller capacity.
• THE 3-SEAL POUCH WITH GUSSET: One manufacturer researched an improvement in the 3-SEAL pouch and developed a style that is formed from a single sheet but provides a double gusset at the bottom. It's Advantage is that it provides greater capacity without the center seam sealing problem. This type has found wide acceptance in the food industry for packaging cake mixes, dry cream and similar products. The same manufacturer pioneered the development of an attachment which allows packaging in an inert atmosphere (gas packaging), prolonging the shelf life of products subject to rapid spoilage by eliminating oxygen from the package.

Pouch papers can be defined as any paper coated or treated with a heat sealable material, used in roll form, that is formed, filled and sealed in one operation on an automatic piece of equipment. The definition may also be applied to foil, cellophane, other films and combinations of these materials.

Heat seal ability is of prime importance to pouch papers. The bond is made by the single application of heat without other glues or adhesives to Siri. This is important in speeding production by eliminating drying time for adhesive to “set.”  Further, it eliminates handling and application of sealing material by the packager and may contribute to simplified machine design.

Thilmany features polyethylene coatings on its pouch papers which are distributed under the name of Polly-Kraft. In addition to polyethylene, other coatings can be applied for heat seal ability including nitrocellulose coatings, poly vinyls, Philofilm, specialized lacquers and waxes.

The paper company is coding most of its pouch papers with extruded polyethylene because the plastic rates so highly in a number of properties essential to good pouch packaging…

Relation to Machines

Converters who supply pouch papers to packagers should be aware of the minimum requirements necessary to produce a package from the standpoint of end product protection, shipping and merchandising. Also, they should be familiar with the type of machinery on which their rolls are to be run.

Briefly, pouch packaging machines operate on a reciprocating or non reciprocating principle. The first is a start and stop operation while the latter, once started, continuous without interruption.

This difference in machine operation may have a bearing on the type of material the converter suggests for packaging since:

Reciprocating machines usually require:

1. Higher tensile strength.
2. Better slip qualities of heat seal coating and paper.

Non-reciprocating machines can usually tolerant:

1. Lower tensile strength
2. Poorer slip qualities (or none) of heat seal coating and paper.

Another factor the converter must consider is pliability vs stiffness. These qualities can have a definite effect on machine operation and will vary from machine to machine. Some require pliability to form packages properly while others require stiffness to fill properly.

The type of heat seal is important. If the seal is face to face, the coated surfaces are brought together and fuse to each other, giving a very strong seal. Generally, and disregarding the protective requirements for the product, less heat seal material is required to give a satisfactory closure. 

If the closure is face to back, the heat seal material is in contact with an uncoated surface. This type of sealing may result in a weaker seam and normally requires more heat seal material. (It is understood that the former refers to coated pouch papers and not to films such as cellophane which are heat sealable in themselves.). *

*The full version of this article can be found in the March issue of Paper, Film and Foil Converter.

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