Confused about picking wraps and pouches? Here's what you need to know to make the right sterile-packaging choices.

Woven fabrics
Fabric wraps have evolved from 140-thread count muslin to 100 percent polyester/continuous-filament wraps. If your fabric wraps are reusable, ask your vendor or manufacturer for studies demonstrating effectiveness and for recommendations for number of uses, laundering times, temperatures and compatible chemicals.

Polyester solves many problems associated with muslin, such as lousy bacteria-barrier properties, excessive thickness and high absorbency. But it presents a new problem: Moisture pools, hindering evaporation during the drying cycle and producing wet packs after steam sterilization. Solve this by adding absorbent materials to very large or metal-containing packs and testing combinations of items, wrapping material, steam quality and sterilizer cycles before and after making any changes in packaging choices.

The costs of disposing of disposables are increasing, and EPA pressures and community guidelines for trash disposal are more strict. Factor this in when considering reusable wraps.

Non-woven fabrics
Non-woven fabrics are made by laying down synthetic and cellulosic or all-plastic fibers much in the way paper is made. Random layering lets the fabric breathe and maintain barrier properties.

Additional advantages of disposable, non-woven fabrics: less bulk; more consistent barrier properties; and much less labor-intensive collecting, sorting, washing, de-linting and inspecting. Disadvantages include the aforementioned disposal problems and less puncture and tear resistance. This is because small, random fibers don't have the tensile strength of continuous fibers.

You might have to change your wrapping procedures; unlike woven material, non-woven fabric shrinks in the heat and moisture of steam sterilization - so you should wrap more loosely. To prevent tray corners' from poking through, examine your trays and smooth out any sharp edges. Add cushioning and absorbency to a heavy tray by placing absorbent towels under it before wrapping.

Some of the older non-woven materials bounce back after un-folding, which can compromise aseptic delivery. Fix this by pulling the wrap's corners down instead of flipping them open. Newer non-wovens have better drape abilities.

Peel pouches
There are peel pouches for steam sterilization (paper/plastic laminate) and low-temperature gas/plasma sterilization systems (Tyvek/plastic laminate). I'm not sure which to use with ozone sterilizers, because they can't sterilize paper or Tyvek/plastic laminate. I haven't been able to get this information from the manufacturer, so if you have an ozone sterilizer or are thinking of buying one, get compatibility/efficacy information.

• Paper/plastic (P/P). These steam sterilization pouches consist of polypropylene laminated to polyester. Polypropylene's high-temperature, heat-sealable layer withstands steam; polyester provides the needed strength.

Polypropylene's narrow temperature range for strong-yet-peelable seals means it's tough to consistently make seals that hold and don't shred the paper when peeling. To open P/P pouches, use the wrist-roll; simply grabbing and pulling could cause shredding or tearing that could let fibers into the package.

Only use P/P pouches for steam sterilization, never for bulky items; you're likely to trap air, compromising sterilization. Large items tend to fall on pouches' edges, making aseptic presentation difficult. Don't buy large, gusseted pouches or pouches with indicator ink inside. Indicators in the v-shaped area at the top are enough.

Never use pouch stock in rolls if there's a pre-formed size option. Roll stock is more costly, more labor-intensive and results in less-reliable seals.

Always place P/P pouches on edge so that the paper breathes while the plastic side traps air. When stacking, leave enough room between pouches to slide your hand between them so steam can enter the pouch. If you double-pouch, ensure the inner pouch is smaller than the outer, and face both paper sides the same way. Folding the inner pouch could trap air. P/P pouches will keep items sterile until the paper side gets wet or punctured, or the seals open.

• All-plastic. In these pouches, polyethylene, a low-temperature plastic with a broad heat-seal range, is laminated to polyester. The result is a strong-yet-clean seal with no shredding. Use these pouches for low-temperature sterilization. Both sides are moisture-proof, so they maintain sterility when wet. For larger items, use header pouches, polyethylene bags with a Tyvek strip at one end to let air and low-temperature sterilant through. All pouches come in heat- and self-seal versions; go with heat-seal because they cost less and take less time to seal.

Container systems
Sterilization containers eliminate wrapping. The exterior plastic or metal acts as the primary bacteria barrier for separate instrument trays inside. You assemble instruments in holding trays and put them in the container, which you seal and place in the sterilizer. Special vents let sterilant and air through the container.

After sterilization, you store the container. When it's time to use the instruments, you can take the container to the OR and directly transfer the internal trays to the sterile field. You can even use the container as the sterile field, dispensing the instruments from the container itself, being careful not to touch the non-sterile edges.

The initial conversion can be expensive, but containers can save you a lot in preparation labor and wrapper costs - if they're in constant use. Never use containers to store sterile packs; they're far too expensive for that. Start by using them only for items that turn over rapidly. You'll soon see the payback in time and money.

Container systems are very durable, but do not abuse them; a dropped lid could hurt barrier properties by creating openings at the damaged edge.

Buy containers with a solid bottom for high-vacuum steam sterilization (recommended) and perforated bottoms for gravity-displacement sterilizers.

Place containers flat on sterilizer shelves, not on their sides or on end. Put items inside the container so they don't block filters, valves or the air-removal system, and let steam contact all instrument surfaces. Ensure the container doesn't trap moisture at cycle's end by setting longer drying times or adding absorbent towels to the container. Follow manufacturer directions for handling, sterilizing and storage. Containers will keep items sterile unless the filters or valves are compromised.

Sterility maintenance covers
If you typically sterilize and store items rather than use them within a week, or if you transport items over a long distance, prevent accidental damage or dust accumulation with sterility maintenance covers (SMCs). SMCs are 3 mil polyethylene bags that don't extend the shelf life; they keep the product sterile. Use SMCs on any packaging if extended storage or outside contamination is possible. Don't confuse a dust cover with an SMC. Dust covers are typically 1.5 mil or 2 mil polyethylene bags used for items, such as anesthesia tubing, that have been sterilized as part of decontamination but don't need to be sterile for use. They keep the items free of dust and contamination from handling.

A packaging poll
Economically, it's ideal to use as few different types of packaging as possible, but to ensure highest quality, you want to use the type optimized for each application. Discuss options with your sterilizer and packaging vendors, infection control manager, end users and purchasing staff.