Use of Chemical Indicators Should Reflect Standards

By Nancy Chobin, RN, AAS, ACSP, CSPM

Q:  I have been using steam tape to place indicator on paper i.e., count sheets, and instrument bags inside of surgical trays before sterilization. I have been doing this for a number of years. My manager informs me that you cannot use steam tape to hold an indicator in place, be-cause "there is no way to validate that the tape is sterile after sterilization." Please clarify or give justification for this statement.

A:  You have presented an excellent question. I have witnessed this practice many times. We need to look at the standards for sterilization to get the scientifically based information.

The Association for the Advancement of Medical Instrumentation (AAMI)’s Comprehensive Guide to Steam Sterilization and Sterility Assurance in Healthcare Facilities (ST-79), 2013 or the most current version should always be your guide. Sterilization technology and standards are constantly changing and the practices of the past were not always based on scientific data. You should have a copy of ST-79 in your department to direct your practices. AAMI standards should also be used to develop policies and procedures for all sterilization practices to ensure consistency in preparation of items.  There should be routine monitoring for compliance with your department’s stated policies.
ST-79, Section 10.5.1 discusses chemical indicators. Chemical indicators (CIs) are recommended because they provide useful information about the specific package/set. There are six types (formerly called classes) of chemical indicators. You should be familiar with the types of chemical indicators and their intended use.

Type 1 – are process indicators such as sterilization tape.  These are designed to differentiate a package that has been in a sterilizer from one that has not.  They also hold wrapped packages together.  Usually these indicators are single parameter meaning they respond to only one parameter of the specific sterilization process.  For steam, they react to heat. The CI contains a chemical that reacts to a specific sterilization process (e.g., steam, EO, low-temperature vaporized hydrogen peroxide with or without plasma, hydrogen peroxide–ozone) with a color change (e.g., the lines on a CI for steam sterilization usually turn black). It is important to follow the manufacturer’s instructions for use (e.g., the expected color change, the proper storage conditions). Some sterilization tape manufacturers place an expiration date on the tape, usually inside the roll or on the outside packaging. Always check for an expiration date before use. If the tape does have an expiration date, it is important to rotate stock to prevent outdates.

Type 2 – Indicators for specific tests.  These include the Bowie-Dick test which measures the air removal performance in pre-vacuum steam sterilizers.

Type 3 -  Single parameter indicators.  These are designed to respond to only one variable of the sterilization process that they are designed to monitor. Single-variable indicators may be used as internal chemical indicators, but multi-variable (Type 4), integrating (Type 5), and emulating (Type 6) indicators provide more information about the sterilization process. It is important to follow the manufacturer’s instructions for use (e.g., the acceptable endpoint change, the proper storage conditions, the expiration date).

Type 4 - Multi-variable indicators are designed to react to two or more of the variables of the sterilization process that they are designed to monitor. They may be used as internal chemical indicators. Most Type 4 indicators show an acceptable endpoint by a color change. It is important to follow the manufacturer’s instructions for use (e.g., the acceptable endpoint change, the proper storage conditions, the expiration date).

Type 5 - Integrating indicators are designed to react to all of the critical variables of the specific sterilization process that they are designed to monitor. Integrating indicators perform in a manner that parallels the performance of biological indicators (BIs). However, it is important to understand that an integrating indicator does not contain live bacterial spores and should not be used as a substitute for a biological indicator. Integrating indicators may be used as internal chemical indicators, in a BI Process Challenge Device also known as “PCD“ to monitor non-implant and implant loads, and in a CI PCD to monitor and release non-implant loads. In defined emergency situations, the results of the Type 5 CI can be used to release an implant before the BI result is available. It is important to follow the manufacturer’s instructions for use (e.g., the acceptable endpoint change, the proper storage conditions, the expiration date). NOTE: PCDs were previously referred to as BI test packs.

Type 6 - Emulating indicators are designed to react to all critical variables of a specified sterilization cycle. They should only be used in the specific cycle for which they are labeled. For example, one of the available Type 6 chemical indicators is labeled for use in a pre-vacuum, ex-press, 270ºF/132ºC, 4-minute cycle. This indicator can be used only in that cycle. Type 6 CIs do not contain spores and should not be used as a substitute for a BI or to release implants. They may be used as an internal CI and inside a PCD to release non-implant loads. It is important to follow the manufacturer’s instructions for use (e.g., the acceptable endpoint change, the cycle the CI is intended to monitor, the proper storage conditions, the expiration date).

Using Chemical Indicators – According to AAMI ST-79, a Type 4 or higher CI should be placed inside every package to be sterilized. For pack-ages that permit visualization of internal chemical indicators (e.g., paper–plastic pouches), an external chemical indicator (e.g., tape) is not required; however, many facilities do affix a piece of tape to the package to label it. For wrapped sets (including organizing trays), the CI should be placed in the center of the set or pack, where sterilant penetration is the most difficult to achieve. (ANSI/AAMI ST77 defines an organizing tray as “a metal or plastic containment device that organizes and protects instruments and components in specified locations within the device and that is usually wrapped with an approved wrapping material.”) “This location might or might not be the center of the package, tray, or containment device” (ANSI/AAMI ST79). For a rigid sterilization container system, the container manufacturer should be consulted for the recommended locations for chemical indicators. If the container manufacturer does not provide recommendations, the following instructions should be adhered to: Two CIs should be placed in opposite corners of the inside basket. For multi-level sets, a CI should be placed in the geometric center on each level. Whenever instruments are separated inside a set (e.g., placed in an organizing basket, autoclaveable bag, or single use tray liner), a CI should be placed inside as well.

A CI should be placed in each paper–plastic pouch (unless the pouch has an embedded indicator as part of the packaging). It should be positioned in such a way that the post sterilization result of the chemical indicator can be seen (e.g., it should be facing up). For larger packs, a CI should be selected that is long enough (some have an extender piece on them) that the end user can easily locate the CI inside the packs.

As we have seen, there is no scientific reason to affix steam tape to indicators or count sheets (see AORN Guidelines for discussion on count sheets inside sets).  While change is sometimes painful, we must keep updated and ensure we are complying with the most current, scientifically based practice.  Your practice should reflect the national standards as published by AAMI. Place your CI inside the package or set as recommended by AAMI to ensure the expected performance of the CI. Contact was made with one sterilization tape manufacturer who confirmed steam tape is penetrable by steam.  However, the major concern is to use chemical indicators as intended.

Nancy Chobin, RN, AAS, ACSP, CSPM, is a sterile processing consultant and educator.

References:

Association for the Advancement of Medical Instrumentation, “Comprehensive Guide to Steam Sterilization and Sterility Assurance in Health Care Facilities, (ST-79), 2013.  

Basics of Sterile Processing, Sixth Edition (2014), Sterile Processing University, LLC.  Chapters 8 and 10.