Health care facilities take great care to achieve sterilization, but they rarely take the same care to ensure that the products are sterile at the time of use, which is, of course, the only time that matters. To keep a product or device sterile, it's crucial to protect and store it with appropriate packaging. The type of packaging you use will depend on your sterilization method. In this article, I'll discuss various things to consider when choosing packaging and some appropriate packaging choices for different types of sterilization.

Functions of Packaging
A package containing a sterile product must perform three main functions:
- It must allow the sterilant to reach all parts of the product being sterilized.
- It must ensure that the sterility of the contents will be maintained until the package is opened.
- It must allow the item to be removed without being contaminated.

Other important characteristics include:
- Compatibility with the sterilization process. Steam sterilization requires adequate air and moisture permeability and the ability to withstand temperatures up to 290 degrees F without deforming. EtO gas sterilization requires materials that will allow EtO to penetrate and entrapped air to escape. Hydrogen peroxide gas plasma sterilization requires noncellulosic packages and adequate air removal. Dry heat sterilization requires packaging that will withstand temperatures above 300 degrees F for long periods of time.
- A tamper-proof closure or seal. The seal should be easy to open, but it should not be reclosable.
- Easy identification of the package's contents.
- Ability to maintain barrier properties under varying temperature and humidity conditions.
- Materials that are free of toxic ingredients and non-fast dyes.

This month, I'll discuss two good choices for steam sterilization: CSR wrap and paper/plastic pouches.

CSR Wrap
CSR wrapping materials, which you can use to wrap surgical packs, instrument sets, towels, and other items, come in reusable and disposable varieties. Traditional reusable wraps (usually composed of 100 percent cotton T-140 material commonly known as muslin), are generally not considered appropriate anymore as a suitable wrapping material, for several reasons. First, the open weave creates an ineffective bacterial barrier, even when the wraps are folded double and then double wrapped to provide four thicknesses of barrier protection. They absorb moisture, creating a pathway for microorganisms, and they tend to wear thin after repeated uses.

A better option may be the newer reusable fabric wraps, which are composed of tightly- woven, synthetic materials chemically treated to provide moisture resistance. These wraps offer greater strength, conformability, and lower cost (depending upon number of uses-most manufacturers provide a mechanism for counting the number of uses). But if you use reusable fabrics, remember that you will still have to sort, launder, inspect, patch and delint them, and they will gradually lose their barrier properties.

If you don't have the ability to maintain reusable wraps, your best bet may be the disposable variety. These wraps are composed of non-woven fabrics (some people term them "paper" wraps, but the material is either all synthetic or a combination of synthetic and cellulosic fibers). The merits of disposable non-woven fabric wraps include consistency of barrier properties, moisture resistance, and simple stock/inventory control. These may be the wraps of choice for steam or EtO gas sterilization. (The ideal package for EtO sterilization is a single non-woven wrap and an all-plastic bag; more on this in a future article.) But disposable wraps do have their disadvantages. Here are some of the common problems that occur with disposable wraps and some advice for how to solve them:

Lack of conformability or "memory": Disposable wraps sometimes conform poorly to the product. Too-small wraps will bind the product too tightly and may result in a "blow-out" during the vacuum stage of sterilization. Large wraps will tend to wrinkle; wrinkles will set during sterilization and hinder aseptic technique during the presentation stage.

Lack of strength: Non-woven fabrics don't have the same tensile strength or puncture resistance of woven fabrics, so take the following steps to avoid tearing them:
- Use towels inside the packages to cushion sharp corners and edges. Use towels to cushion your carts and storage racks, as well.
- Avoid stacking trays on top of one another.
- Lift, never slide or drag, packages from their storage areas.
- Try wrapping instrument sets inside the tray (see the May Infection Prevention column).

Moisture retention: Disposable wraps tend to retain moisture during the sterilization process, resulting in wet packs. To avoid this, don't overload your trays or packs; the more surfaces there are in the pack, the greater the chance that condensation will form. You can also try using absorbent towels to soak up the condensate in the package. If you still get wet packs, you need to talk with a biomedical engineer about changing the quality of the steam in your sterilizer; it may be too wet.

Just a note about sequential wrapping (wrapping a product and then wrapping the wrapped package) versus using a single wrap of two layers. Until recently, many believed that sequentially wrapping packages provided additional protection from dust infiltration and eased aseptic presentation. However, there is no evidence that sequentially wrapping packages offers any more protection from dust infiltration; the only issue is presentation technique. If your circulating nurse opens the outer wrap and the scrub nurse opens the inner wrap, you must use sequential wrapping. But if the circulator opens both packages, you can save some time by using a single, double-layer wrap.

An inexpensive, wide, flat or serrated hot bar sealer is all you need for sealing paper/plastic pouches.

Paper/Plastic Pouches
Designed initially to contain single instruments, paper/plastic peel pouches are now used to package everything from sterile gauze packs to uncomplicated instrument sets. Paper/plastic pouches are composed of a special grade of paper on one side and a lamination of polypropylene and polyester on the other. They come in a variety of sizes, both as preformed pouches and rolls of tubing. Paper/plastic pouches offer a number of advantages-they're easier to work with than double CSR wraps, allow you to see the contents, are relatively inexpensive, seal quickly and easily and afford simple aseptic presentation. A potential disadvantage is that the paper side is subject to moisture contamination and easy to compromise.

The most crucial features of the paper/plastic pouch are the chevron and side seals, which are made by melting the polypropylene into the paper fibers. The seals must be strong enough to withstand the rigors of high vacuum steam sterilization without rupturing. They also need to provide a quick, clean peel without shredding the paper.

To ensure that your paper/plastic pouches have adequate seals, always purchase them from a reputable supplier and test them using the devices you sterilize most often. Don't bother peeling the pouches before sterilization to test the peelability of the seals; the seal strength will change during the sterilization process. Teach your staff to use the "wrist-roll" technique for opening pouches-quickly pulling the sides apart will almost always result in tearing of the paper fibers and/or fracturing of the plastic.

Here are some other considerations and recommendations for using paper/plastic pouches:

Tubing versus preformed pouches. Pouch material comes either as preformed pouches or rolls of tubing. Some facilities mistakenly think they are saving money by purchasing only tubing and trying to customize each pouch. However, using a preformed pouch is always the less expensive option, when you consider the labor costs involved in cutting the tubing to length and trying to make a strong yet peel-able chevron seal. Don't use tubing when you can use a preformed pouch of an appropriate size. Use it only for long, narrow devices like catheters for which there is no preformed pouch available.

Flat versus gussetted. Many believe that the gussetted pouches "hold more" than flat pouches. In fact, the opposite is true. A 6 x 8 pouch will hold more than a 4 x 2 x 8 pouch even though both have the same dimensions. Gussetted 4 x 2 x 8 pouches have two serious problems: they include 12 inches of plastic, which is impermeable to steam and air; flat 6 x 8 pouches only have 6 inches of plastic and allow more steam and air to penetrate. Gussetted pouches are also difficult to seal. For those reasons, I can't recommend them.

Wide flat seals versus ribbed seals. Tests have shown that there is no appreciable difference in the strength or the peelability of one style of seal over the other.

Heat-seal vs. self-seal. One way to increase productivity and reduce cost is to use heat-seal pouches. Self-seal pouches are more expensive and take longer to close than heat-seal pouches. Use self-seal pouches only when it is impractical to have a dedicated heat sealer in the area where the packaging is being done. A note: It makes no difference whether or not the fold above the tape seal is perforated or scored. Either will work as long as you do the tape sealing correctly. Also, the width of the tape is not important as long as it is wide enough to keep the package sealed during sterilization and subsequent handling.

An inexpensive, wide, flat or serrated hot bar sealer is all you need for sealing paper/plastic pouches; you don't need a sealer with Teflon on the bars unless you are sealing all-plastic bags.

Single versus double pouching. For most instruments, single pouches will do. Use double pouches only if you need to contain small items that you want to put into the sterile field. The inner pouch doesn't have to be hermetically heat sealed as long as the items are sufficiently contained.

It's generally best not to fold the inner pouch, since folding increases the chances of trapping air or moisture. However, if you are sterilizing with pre-vacuum steam or EtO gas, folding the inner pouch should not cause any problems.

General recommendations:
- Buy pouches with tack seals above the chevron so that this area does not collect dust.
- Buy pouches with minimal printing on them and printed chemical indicators only above the chevron seal. Printed internal indicators are of dubious value and add cost.
- Always place pouches on edge and contain them loosely (do not pack them too tightly) in a basket during sterilization.