Using Indicators

December 1, 2000

Using Indicators

By Natalie Lind, CRCST, CHL, ACE

The buzzer rings on the dryer, you check the clothes, but the load is still damp. Thetimer sounds on the stove and you check the cake in the oven. The directions say it shouldbe done now, but it needs a few more minutes. These timers with audible sounds areindicators. In both cases the prescribed exposure times and temperatures had been met, andyet an inspection indicated that each process was not yet successful.

Several times each day we use various indicators to aid in determining if requirementshave been met and that processes are being carried out correctly. We step on the scale tocheck for indication of weight loss or gain. We check the gas gauge to see if we need fuelin our vehicles.

Common indicators used in healthcare organizations are those that measure thesuccess--or failure--of the sterilization process. These indicators are particularlyimportant because, unlike many of the other processes we measure at work and at home,there is no way to tell if our process was successful without them.

When a load is removed from the sterilizer, barring any major factors such as visiblewet packs, it is impossible to tell if the sterilization process was successful by visualinspection. For that reason, we rely on sterilization indicator systems to provide us withadditional information about the success or failure of the process.

Sterilization indicators provide valuable tools that assess the quality of the goodssterilized. These tools help prevent the release and use of items which may be unsafe.It's easy to agree that the use of indicators is a positive form of quality assurance.However, agreeing with the concept isn't quite enough. We must understand the basicinformation about indicators and how to use them correctly.

Before using indicators, it's a good idea to review the common types associated withthe sterilization process and the function and purpose of each. Perhaps the most commontype of visual indicator used in sterilization is the chemical indicator (CI). CIs come ina wide variety of sizes, shapes, and styles. Typically, they are broken into twocategories: external and internal.

External indicators are designed to provide the handler and user with a visualindication that the item was exposed to a specific sterilant. This type of indicator aidstechnicians in distinguishing processed from unprocessed item. They are often in the formof tape, small cards, or dye spots on the exterior of medical packaging. Externalindicators change color when exposed to a specific sterilant and that color changeprovides evidence that the item was processed. It is important to remember that theseindicators do not prove that an item is sterile; they merely prove that an item came incontact with the chosen sterilant.

Internal indicators also provide evidence of the presence of a sterilant. However,internal indicators are placed inside each package prior to sterilization and measure thepenetration of the sterilant into the pack. This measurement is designed to provide thepackage user with evidence that a sterilant was present inside the pack. Internalindicators can detect packaging and placement failures such as air entrapment, incorrectpackaging selection and/or application, and improper loading of the sterilizer (Figure 1).They may also detect mechanical failures such as air removal system failures.

As is the case with external indicators, internal chemical indicators do not prove thatan item is sterile. However, they are the only way to measure pack penetration in everypackage. Most common methods of sterilization rely on direct contact between the sterilantand the object being sterilized. A visual indicator that detects the presence of asterilant within the pack provides the user with some assurance that contact was made.

Chemical Indicators

Most technicians use chemical indicators--dozens, even hundreds of times per shift.They are easy to use and easy to read. In fact, the biggest danger in using chemicalindicators may be their familiarity. Because they are a part of every pack that isassembled and sterilized, it is easy to take them for granted.

To provide the desired measurement, chemical indicators must be placed properly. Whilethis is easy for external indicators, there is a chance of error when placing internalchemical indicators. Since the goal of the measurement process is to measure packpenetration, internal chemical indicators should be placed at or near the center of thepack. Placing them on top of the pack contents will not provide the same measurement ofpack penetration. Since the contents of each pack are different, the assembler shouldplace the indicator in a place where air would most likely be entrapped if it remained inthe package. That placement provides the best measurement for individual pack penetration.

In addition to placing indicators strategically within the center of the pack, eachindicator should be placed in a manner that makes it easily accessible for the user.Long-handled indicators may need to be used for more complex packs.

One of the greatest challenges in the use of chemical indicators is maintaining theability to assess the outcomes of the indicators on and within every package. During thecourse of one shift, sterilizer operators and product users will handle hundreds ofpackages that contain indicators. The vast majority of all the packages handled will haveindicators that indicate no potential problems. It is easy to be lulled into complacencywhen handling these familiar packages. When this happens, technicians and users often failto see the indicators themselves and instead become so accustomed to indicators withacceptable readings that they may not notice a failed measurement. Both handlers and endusers must be constantly alert to indicators that have not changed color, and toindicators whose color is suspect.

Handlers and users must also understand procedures for correct use and interpretationof their chemical indicators. That means reading the instructions that are included withindicators and familiarizing themselves with manufacturers' recommendations for use.

It is also important to recognize that chemical indicators and chemical integrators aredifferent. Chemical indicators are designed to detect the presence of a specificsterilant. Chemical integrators are designed to detect the presence of a specificsterilant and they also incorporate a time factor. In other words, these products do notdevelop a reading upon first contact with the sterilant. Instead, they are designed torequire exposure to the sterilant for a specific period of time before they change color.

Figure 1: Raven's ProChem air removal test.

Unexposed | Fail | Pass

Biological Indicators

Another indicator used by healthcare facilities in assessing the quality of theirsterilization process is the biological indicator (BI). BIs contain live bacterial sporesand are designed to measure the sterilization cycle's ability to actually kill spores.Biological indicators are the only sterilization quality assurance tests that provide thisindication (Figure 2).

There are many types of biological indicators on the market. It is important to followmanufacturer's instructions for use on the brand that your facility uses. All biologicalindicators work in the same basic fashion. The live bacterial spores are subjected to aroutine sterilization cycle. Upon completion of the cycle, the spores are incubatedaccording to manufacturer's guidelines. If any spores have survived, the indicator willexperience a color change. If all spores have been destroyed, the indicator's color willremain unchanged. As with chemical indicators, it is important to use biologicalindicators in accordance with manufacturer's instructions. Failure to do so may result inincorrect readings.

The use of chemical and biological indicator systems can provide sterilizer operatorsand product users with some assurances that the sterilization process has been successful.When used in conjunction with a comprehensive plan for cleaning, inspection, assembly,packaging, and sterilizer loading, they can help to ensure that the products used inpatient care are as safe as possible.

Natalie Lind manages the Sterile Processing Department at Innovis Health, Fargo,North Dakota. She also serves as a Sterile Processing consultant and educator throughoutthe United States and Canada.