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To be sure that you're achieving sterilization no matter what kind of method you use, it's critical to monitor the entire process-that is, you must observe, detect and record all the functions before, during, and after the sterilization process. It's important to realize that sterilization is a process that begins when a reusable product is used and ends when you are about to use it again-it does not stop and start with the opening and closing of the sterilizer door. To ensure that you are truly creating sterile products, you need to form written procedures for each step of the process and make sure to make a person or persons are responsible for every single step.
The procedures should include:
How to transport the item to the decontamination area.
How to handle and clean the item in the decontamination area.
How to assemble and package the item for sterilization.
How to determine which sterilization process is appropriate, and how to properly sterilize the item.
How to check if the item was properly sterilized.
How to store the item.
How to transport the item to the user area.
How to present the sterile product at the surgical site.
Unless you monitor the entire process, from beginning to end, you can't be sure that it's been effective. Remember that if any step is out of control, the entire process is out of control.
In this article, I'll describe the three methods used to monitor the effectiveness of a steam sterilizer-mechanical, chemical, and biological. For steam sterilization to be effective, the steam must contact every area of the items being sterilized with saturated steam that is at the right temperature, for a period of time that is appropriate for that temperature. Since it's impossible to measure the steam temperature in every package, you can use these monitors to measure conditions within the chamber.
Mechanical Monitoring
The single most dependable method for understanding the events inside the sterilizer chamber is monitoring the temperature and pressure during and after every load.
To measure temperature, older sterilizers have a liquid filled bulb and a capillary system connected to a mechanism that makes a tracing on a chart recorder. It's important to scrutinize and think about the somewhat complex information on the chart. Obviously, you want to know whether the sterilizer reached the desired temperature for the appropriate length of time. But also consider whether the sterilizer is providing signs that it is about to malfunction. For example, if the slope of the curve representing the time the sterilizer takes to come up to temperature is not the same, cycle after cycle, for similar loads, it may mean that the lint trap is becoming clogged, or that air is leaking into the chamber.
Newer sterilizers have electronic sensors directly connected to a control panel that gives a visual readout and record keeping in the form of a printed tape. It is no less important to carefully analyze the information on the panel display and the printout.
Regardless of how the information is portrayed, mechanical monitoring will tell you more about what is happening in the chamber than any other means and should be thoroughly understood and applied intelligently. Check the record carefully at the end of each cycle before removing the load.
Chemical Monitoring
Chemical indicators can help you detect potential sterilization failures resulting from:
incorrect packaging;
incorrect loading of the steri- lizer; or
sterilizer malfunction.
A lot of facilities rely very heavily on chemical monitoring, believing that it is easy to do and highly dependable. Unfortunately, they are incorrect.
It is true that it is very helpful to have a chemical indicator on the outside of every package as a simple signpost that the item has been through a sterilization process. These indicators tell you almost nothing about what has happened inside the package, however.
Using indicators inside of packages, where they will give you useful information, is much more challenging. Placing chemical indicators indiscriminately at the center of every pack is a waste of time and money and can lead to a false sense of security. Remember, chemical indicators can only tell you if the area where they are received steam. For this reason, they are useful only if you place them within the package in a place where air can potentially be trapped.
For example, a chemical indicator inside a peel pouch inevitably rests against the paper side, an area very unlikely to trap air. A chemical indicator packaged with instruments in a mesh-bottom tray also tells you very little, since air is unlikely to be trapped here. An internal indicator on the top of a basin set, just under the wrap, is also a waste of time and money, since it will not tell you if the basin set was placed improperly on the sterilizer cart. The proper place, the only place where air can be trapped, is in the bottom of the basin set, preferably between the two basins in the towel used to keep the basins apart. Examine your policies regarding the use of internal chemical indicators. You don't need to place them in every package; rather, you should use them intelligently in only those packages that represent a challenge to the sterilization cycle.
Also remember that not all chemical indicators are created equal. I recommend running both good and bad cycles with the indicators you are testing in various places within a variety of packages relative to what the product is designed to detect. Try to determine which indicators produce the most predictable and reproducible results.
If you have a pre-vacuum steam sterilizer, you must perform a Bowie-Dick type chemical indicator test whenever the sterilizer is shut down for any reason. When a sterilizer is shut down and allowed to cool, the door seals and vacuum pump seals shrink. If they are defective, they won't return to their original shape when the sterilizer goes back into service, allowing air to leak into the chamber. The steam will then carry the non-sterile air in the chamber into any packs that are in the chamber. The same problem can occur if your steam lines are leaky and pumping air as well as steam into the chamber.
The Bowie-Dick test can help you determine whether either problem is present. It uses an approximately 8" x10" sheet of paper printed with an indicator ink pattern. Place it in a linen pack or in a test pack and run it through the sterilizer cycle alone in a pre-vacuum cycle. The ink should change in a uniform color.
Biological Monitoring
Biological indicators represent the actual destruction of viable organisms, so they are considered more representative of the physical and/or chemical parameters that reduce a viable population of microorganisms to an acceptable probability of sterility. Standards-setting bodies such as AAMI and AORN as well as JCAHO recommend that you use biological indicators at least weekly in all sterilizers and in every load when implants are sterilized.
Biological indicators contain spores of organisms that exhibit high, stable, and reproducible resistance to the mode of sterilization you are monitoring. Most steam biological monitors use Bacillus Stearothermophilus.
One type of indicator uses a strip of paper impregnated with spores. The strip is contained in a glassine envelope. You place the indicator in a challenge linen pack, run it through a steam sterilization cycle, and send the strip to a laboratory to be incubated. Any subsequent growth indicates a potential sterilizer or packaging problem.
Another type of biological indicator uses a spore strip in a self-contained sealed ampule of growth medium. After running the indicator through a cycle, you crush the ampule to release the growth medium and activate the spores. You can then incubate the spore strip on site, allowing any viable organism to grow. Some self-contained biological indicators allow you to bypass the incubation process by taking advantage of fluorescence, which occurs when an enzyme in the spore reacts with a substrate in the growth medium. Any living spores glow when the indicator is exposed to ultraviolet light.
As with chemical indicators, use special care when placing biological indicators within the load. They only provide useful information if they are placed properly. By far the most popular use of biological indicators is as a self-contained indicator in a BI test pack. This removes the problems associated with the need for a laboratory, as well as proper placement and challenge.
Keeping good records of your monitoring efforts is an important element in any quality assurance program. Have a knowledgeable person review them regularly. In the final analysis, effective sterility assurance does not rest on mechanical, chemical, or biological monitoring. The single most important aspect of sterility assurance is the health care manager's understanding of the sterilization process.
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