Chemical apparatus and process disinfecting – deodorizing – preser – Analyzer – structured indicator – or manipulative laboratory... – Calorimeter
Reexamination Certificate
1999-08-05
2002-12-03
Alexander, Lyle A. (Department: 1743)
Chemical apparatus and process disinfecting, deodorizing, preser
Analyzer, structured indicator, or manipulative laboratory...
Calorimeter
C422S051000, C422S067000, C436S001000, C436S164000, C436S166000, C436S169000
Reexamination Certificate
active
06488890
ABSTRACT:
FIELD
This invention relates to sterilization indicators, sterilization information and methods of monitoring articles to be sterilized. The present invention relates particularly to a sterilization indicator that can be machine read to provide a user with information relating to a sterilization process. With the present invention, information relating to the efficacy of a sterilization cycle can be machine read and/or electronically linked to integrated electronic information systems throughout the health care provider system.
BACKGROUND
Sterilization is the act of killing bacteria and other microorganisms on surgical instruments, devices and implants. Sterilizers are designed to kill all viable living organisms within a sterilization chamber. This is challenging, as objects can be contaminated with any of a number of different types of bacteria, some more dangerous and tougher to kill than others.
Sterilization indicators show whether a sterilizer achieved adequate (e.g. lethal) conditions. One kind of sterilization indicator is known as a chemical indicator. Chemical indicators respond to one or more of the critical parameters of a sterilization process. Typically, chemical indicators either change color or have a moving front with an endpoint to provide information concerning the sterilization process.
The Association for the Advancement of Medical Instrumentation {AAMI} has recommended practices and standards that cover sterilization testing, including the use of chemica indicators. Hospitals frequently look to AAMI to establish sterilization assurance procedures. See e.g.
Good Hospital Practice: Steam Sterilization and Sterility Assurance,
AAMI Recommended Practice, Section 6.4 (1988). Hospitals also look to other standards and regulatory agencies for validation, routine control and other procedures for obtaining, recording, and interpreting data to show that a sterilization process complies with a predetermined sterility assurance level. Other recommendations and guidelines are provided by the Joint Commission on Accreditation of Hospitals (JCAH), the Center for Disease Control, Association of Operating Room Nurses (AORN), American Society for Healthcare Central Services Personnel (ASHCSP), and the various state laws.
AAMI categorizes chemical indicators in five classes. See
Sterilization of Health Care Products—Chemical Indicators—Part
1:
General Requirements,
American National Standards Institute (ANSI)/AAMI ST 60—(1996). Class 1 relates to process indicators. Process indicators are intended for use with individual packs to demonstrate that the pack has been exposed to the sterilization process and to distinguish between processed and unprocessed packs. Class 2 describes indicators for use in a specific test procedure such as a Bowie-Dick test. Class 3 relates to single parameter indicators, and class 4 to multi-parameter indicators. Multi-parameter indicators are designed to respond to two or more critical parameters of sterilization and indicate exposure to a sterilization cycle at stated values of the chosen parameters. For example, time, temperature and saturated steam are critical conditions for a steam cycle. Class 5 chemical indicators are known as integrating indicators. These are indicators designed to react to all critical parameters over a specific range of sterilization cycles.
Integrating chemical indicators are described in U.S. Patent Reexamination Certificate No. B1-3,981,683, (Larsson et al.) and U.S. Pat. Reissue No. 34,515 to Foley. Other chemical indicators are described in U.S. Pat. Nos. 3,114,349; 3,313,266; 3,341,238; 3,652,249; 4,138,216; 4,382,063; 4,576,795; 4,692,307; 4,579,715; and 5,451,372 (the entire contents of each of which are herein incorporated by reference).
Another kind of sterilization indicator is known as a biological indicator. Biological indicators use a large number (usually a million or more) of microorganisms that are highly resistant to the sterilizing agent of the sterilization cycle being monitored.
See Sterilization of Health Care Products—Biological Indicators—Part
1:
General Requirements,
ANSI/AAMI ST 59 (incorporated herein by reference). Biological indicator technology is also disclosed in U.S. Pat. Nos. 3,661,717 and 5,073,088 (the entire contents of which are herein incorporated by reference).
Minnesota Mining and Manufacturing Company (3M) sells Attest™ Rapid Readout Biological Monitoring Systems. These systems include a biological indicator that is capable of exhibiting fluorescence after a failed (non-lethal) sterilization cycle, and an auto reader. To test a steam sterilizer with an Attest system, the user places the biological sterilization indicator into the steam sterilizer along with the items to be sterilized. After the sterilization cycle, the indicator is placed in an Attest auto reader (e.g. model 190). The auto reader has an incubator and a means for reading the biological indicator to determine whether the sterilization indicator exhibits fluorescence. If the steam sterilization cycle was lethal, the auto reader will not detect fluorescence within a predetermined time. If the cycle was non-lethal, the auto reader will detect fluorescence associated with the biological sterilization indicator in the predetermined time. Even with this instrumentation, a user is required to manually record the results provided by the auto reader.
Other international standards organizations and regulatory agencies describe sterilization indicators for monitoring sterilization processes in the health care context. The International Organization for Standardization (ISO) includes many standards similar to those described above. See ISO 11140-1:1995 for chemical indicators. European Standard Nos. EN 867-1 and 866-1 also include many standards similar, but not identical to those of AAMI and ISO (see e.g. The European Committee for Standardization's European Standard No. EN 867-1,
Non
-
biological systems for use in sterilizers—Part
1: General requirements).
When a U.S. hospital designs its sterilization assurance practices, it often evaluates equipment control, exposure control, pack control and load control. Equipment control evaluates sterilizer performance. For example, a Bowie-Dick pack can indicate the failure of the vacuum portion of a steam sterilization cycle. Load control is often a biological indicator placed in the sterilization chamber.
Items to be sterilized are often wrapped in sterilization wrap. The wrap is typically secured with an exposure control indicator (e.g. indicator tape). The resultant assembly is referred to as a pack. Exposure control is typically a chemical indicator placed within the sterilization chamber but outside the pack that is being sterilized. Exposure control identifies processed: from unprocessed packs. Pack control is usually a sterilization indicator placed within a pack that evaluates conditions inside an individual pack. After a successful-sterilization cycle, the articles within the sterilization packs remain sterile until the pack is opened. As a result, packs are usually opened in a specially prepared and maintained sterile field in the operating room just prior to their use. However, commercially available sterilization indicators found within packs cannot be read prior to opening the pack because sterilization wrap is typically opaque. If the sterilization indicator inside a pack indicates a failed sterilization cycle, there are many problems in finding out about it just prior to use of the items within the pack. The problems are multiplied when the sterilization indicator identifying a failure is found within the specially prepared and maintained sterile field.
The importance of sterilization assurance in hospitals requires constant attempts to better utilize sterilization indicators. A user typically visually inspects chemical indicators to obtain information from the indicator. Some users find it difficult to subjectively determine whether a chemical indicator has changed color. This is particularly a problem for a user who suffers from color bl
Alexander Lyle A.
Burtis John A.
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