What You Always Wanted to Know About Wrapping Materials

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What You Always Wanted to Know About Wrapping Materials

By Julie Stoller, CRCST

The Food and Drug Administration (FDA) classifies sterilization wraps as Class II medical devices requiring the following performance standards: "The prime purpose and function of a packaging material (pack, sterilization wrapper, bag, or accessories) is to enclose a medical device that is to be sterilized by a healthcare provider. It is intended to allow sterilization of the enclosed device and also to maintain sterility of the device until it is used."

Wrapping materials are classified in two categories: woven reusable materials and nonwoven materials intended for single use. This article provides a close look at the various types of wrapping materials and the importance of wrap compatibility with the sterilization process chosen. In addition, the role the Central Service technician plays in achieving the desired outcome of properly sterilized products will be discussed.

There are three important parameters that must be met for any type of sterile packaging used. The first is to provide an effective barrier between the package contents and microbiological contamination, the second is to allow for penetration of the chosen sterilant, and the third parameter is that the package must be constructed in a manner that allows the package to be opened aseptically.

Multiple-use or Reusable Textiles

All wrappers made of woven textiles are reprocessable and must be laundered between use. Woven textile fabrics to be used as sterilization wrappers are made of natural fibers of cotton, linen, and/or blends of cotton and synthetic materials, such as polyester (nylon) and chemically treated fibers (Quarpel), in various thread counts (number of threads per square inch) and thread weights. The higher the thread count, the denser the barrier.

Early Woven Textiles

Cotton muslin was one of the first fabrics introduced to the healthcare industry as a multi-use wrapper. It has a thread count of 140 threads per square inch and is 100% loosely woven cotton. To enhance the barrier qualities, a double wrap was recommended. It was later discovered that the effectiveness was compromised during the sterilization process once it became wet, regardless of the number of layers used.

Pima cotton or T-280 is a more densely woven cotton fabric with improved barrier qualities and capabilities for withstanding repeated use and laundering. This fabric was originally developed by the Shirley Institute in Manchester, England, during WWII and was used in flight suits. Pima Cotton was replaced by a polyester/cotton blend.

The most common reusable textiles used in healthcare facilities today are blends or barrier cloth. This type of woven wrapper is made of a combination of two or more types of fibers in one yarn for the purpose of maximizing the benefits of their individual performance characteristics. In many healthcare facilities, the most popular blend is a 50% polyester/50% combed cotton percale. The benefits of this material are that it is wrinkle-free, resistant to abrasion and linting, and very durable. One negative aspect of this fabric, however, is its low water-resistant capability. As mentioned earlier, a chemical treatment (Quarpel) can be applied to increase moisture resistance. Information for proper application of this water-repellant chemical should be obtained from the manufacturer. The healthcare facilities that choose woven textiles for their sterile wraps must have a policy in place to inspect the fabric for any defects.

Non-woven, Single-Use (Disposables)

Non-woven, single-use or flat wraps are made by methods other than weaving, allowing washed paper pulp, cellulose fibers, and synthetic fibers of nylon and/or other plastic polymers to be pressure-bonded together to form sheets of fabric.

Washed paper pulp, or wet-laid fabrics, consists of wood pulp and polyester. A blend of these fibers is suspended in water to form slurry--a thin mixture of water and any of several fine insoluble materials--to ensure uniformity. The water is then drained, resulting in a durable material suitable for many uses.

Spunlace fabrics, such as wet-laid fabrics, are composed of wood pulp and polyester. The difference between the two is in the manufacturing process. The fibers of spunlace fabrics are subjected to high-pressure water jets that mix or entangle the fibers, producing a soft, drapable material.

Polypropylene base is a material made of polypropylene pellets that are melted and then extruded in one continuous filament, then bonded together to form a durable fabric. Another polypropylene-based nonwoven material, referred to as spunbond/meltblown/spunbond, is from continuous, molten filaments that are formed by in-line melt spinning. Meltblown materials are similar in that they are formed from a polymer by in-line melt spinning; however, the fibers are finer and not continuous. The most popular of the nonwoven materials used is made of a three-layer polypropylene material. It comes in a number of different weights, each designed to accommodate a particular application. The two-layers are composed of long, continuous fibers that account for the fabric's strength and abrasion resistance. The center layer consists of a dense mat of meltblown fibers that account for its effectiveness in resisting the penetration of liquids and bacteria while permitting the penetration of steam to achieve sterilization. These polymer disposable flat wraps are low-linting, soft to the touch, and drapable.

Wrapper materials

Wrapper materials must incorporate the following guidelines:

  • Allow adequate air removal and steam penetration of the package contents.
  • Provide an adequate barrier to the penetration of microorganisms.
  • Provide an adequate barrier to fluids.
  • Resist tearing or puncturing.
  • Have proven seal integrity.
  • Allow for ease of aseptic presentation.
  • Be free of holes.
  • Be free of toxic ingredients and nonfast dyes.
  • Be low-linting.
  • Be shown to be cost-effective by value analysis.

There have been many studies on the maintenance of sterility or shelf-life of a sterile package, most discussing whether time or events should be the bases of determination. Several studies have confirmed the value of event-related policies. This practice reduces labor and supply costs. There are important factors to consider when incorporating event-related practices. Types of wrapping or packaging materials used must be resistant enough to take abuse in handling and resist tearing or puncturing. The type of storage (open or closed shelving) and storage area conditions must be monitored to assure stable environmental conditions such as temperature and humidity. Lastly, the personnel handling the sterilized items must be educated to know proper handling procedures. Many healthcare facilities are converting to event-related sterility versus the previous practice of expiration dating. In expiration dating, a load sticker is placed on the package displaying the date the product was sterilized and the load number. This is then used as a tool for controlling the facility's inventory.

What CS Technicians Should Know About Wrapping

CS technicians must have an understanding of how to properly select and apply the correct wrappers for the sterilization method chosen. The manufacturer and distributors must be able to provide detailed specifications regarding the properties of the product as well as documentation of acceptable results of its past performances. Improper selection of materials and packaging application can and will impede the sterilizing process.

Technicians are also responsible for quality assurance issues. They must assemble each package with care, being observant not to tear or damage the wrapper. Each package is uniquely organized, depending upon content, to promote the sterilization process. Special attention must also be given to how the sterilizer is loaded.

There have been many improvements in the world of wrapping materials and, as always in the field of Central Service, there is constant change happening all around us. New sterilizing equipment results in new wrapping materials and improved wrapping techniques. Healthcare professionals must be committed to staying current regarding these technological improvements. Always remember that patients have put their trust in our hands.

Julie Stoller, CRCSD, works in the Central Processing Department as a case cart technician at Innovative Health Hospital, (Fargo, ND).

For a list of references, access the ICT Web site.

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