In a previous column,1 we discussed the importance of clear and appropriate standards for the cleaning of medical devices. The cleaning of reusable devices, typically in healthcare settings, is a particular challenge. As reusable device designs become more sophisticated, the combined efforts of manufacturers, health care practitioners, and regulatory agencies will be needed in order to develop safe and effective instructions for use in reprocessing reusable medical devices in health care facilities.
Developing a basic understanding of cleaning issues such as device materials, surface finishes, available cleaning equipment, and the end user of the specific device—in the early stages of the device development—will help the medical device manufacturer to generate successful cleaning methodology. In doing so, the resulting methodology and the associated instructions will not only be satisfactory from a regulatory perspective but will also assure that the cleaning methods, as executed by the end user, will effectively remove soil from the device when in routine clinical use and thus maintain patient safety.
Current U.S. Food and Drug Administration (FDA) guidance,2 will be supplemented by a newer FDA document3 that is available in draft form. In the draft guidance document, the FDA qualifies the capabilities of spore log reduction testing. The document reads, in part: “FDA does not recommend the use of spore log reduction testing as a method to determine the effectiveness of the cleaning methodology. It is unclear whether or not the removal of bacterial spores directly correlates to the removal of clinical organic soil from the devices. Such testing only indicates how well a process reduces spore count, and provides no information on any other component of organic soil.”
The draft document makes reference to an Association for the Advancement of Medical Instrumentation (AAMI) Technical Information Report4 as providing a compendium of information about currently available techniques. There is a newer 2011 document.5 Updated documents are inevitable, and it will be interesting to see how government documents are harmonized with updates of industry documents.
AAMI TIR30:2011 provides information regarding test protocols, test soils, and acceptance criteria in order for manufacturers to validate the cleaning process for reusable medical devices. The guidance document includes device design, materials selection, and surface changes (materials compatibility) issues produced by reprocessing. It then discusses cleaning processes that are available in health care facilities including cleaning agents, manual and mechanical cleaning processes, as well as markers and verification tests. The document continues with test soils, test methods, acceptance criteria, a simulated-use test protocol, and a summary of regulatory documents including FDA guidance documents.
The writers of the document recognize two important provisos, both related to evolution and awareness. The first is the evolution to ever more complex medical devices. The second is the evolution and/or identification of new pathogens. The document excludes performance of cleaning processes performed in health care facilities. Device manufacturers are responsible for developing cleaning processes that can be performed effectively in health care facilities.
A plethora of guidance
Additional guidelines have been developed to provide assistance to device manufacturers in designing, testing, and labeling of devices intended for reuse in health care facilities.
For example, another AAMI Technical Information Report6 covers a number of general topics related to design considerations for reusable medical devices. The International Organization for Standardization (ISO) standard, Sterilization of Reusable Devices,7 describes requirements for the information provided by medical device manufacturers so that medical devices can be reprocessed in a safe manner. The American Society for Testing and Materials (ASTM) standard specifications provide guidance on many issues relating to surgical instruments and implants.8 ASTM is also developing a number of guidance documents dealing directly with reusable devices.9-11 Other local, national, and international guidelines may be applicable in a particular situation. Given the constant impetus to revise, modify, and harmonize standards, the reader is advised to use the information here as a guideline and to utilize the most recent updates.
The proverbial elephant
The perennial pachyderm in the parlor—an issue that perhaps cannot be definitively addressed by any overarching documents—remains the issue of specifying maximum level of residue markers (in this case primarily biological residue) that must be achieved for a given device.
Because cleaning endpoints have not been specified in AAMI TIR 30:2011, a major challenge faced by instrument manufacturers is determining how clean is “clean.” The TIR compendium has provided a number of references that address issues regarding acceptance criteria for cleaning effectiveness. Based on a review of published data for various types of reusable devices, the average levels of the various markers after cleaning of reusable devices are indicated in Table 1. It should be noted that endotoxin markers may be productively used when validating critical devices that enter the sterile body cavity.
Table 1. Acceptance Criteria, Effectiveness of Cleaning Processes for Reusable Medical Devices (Source: Data derived from references in AAMI TIR30)
||< 6.4 µg/cm2|
|Carbohydrate||< 1.8 µg/cm2|
|Hemoglobin||< 2.2 µg/cm2|
|Endotoxin||< 2.2 EU/cm2|
|Bacterial Spore Reduction
These benchmarks are indicated to be reasonable starting points. While lower limits (by 1 to 2 orders of magnitude) are possible, notably for protein, they are not realistic at this point; artifactual contamination during normal handling is likely to be a limitation.
After all is said and done, the manufacturer must successfully incorporate the wealth of information into an actual validation process. As an example of how one might use the guidelines and compilations of collective wisdom, a companion article outlines case studies describing the design and validation of cleaning techniques for reusable medical devices.
1. Kanegsberg B, Kanegsberg E, Broad J. Read (and Write) the Fabulous Manual,Controlled Environments. 2012:June.
2. U.S. Food and Drug Administration. Labeling of Reusable Medical Devices for Reprocessing in Healthcare Facilities: FDA Reviewer Guidance, Office of Device Evaluation. April 1996.
3. U.S. Food and Drug Administration. Draft Guidance for Industry and FDA Staff Processing/Reprocessing Medical Devices in Health Care Settings: Validation Methods and Labeling. May 2, 2011.
4. AAMI TIR30:2003 (earlier version of Reference 5).
5. AAMI TIR30:2011, A compendium of processes, materials, test methods, and acceptance criteria for cleaning reusable medical devices.
6. AAMI TIR12:2010, Designing, testing, and labeling reusable medical devices for reprocessing in health care facilities: A guide for medical device manufacturers.
7. ISO 17664:2004 Sterilization of medical devices—Information to be provided by the manufacturer for the processing of resterilizable medical devices.
8. Kanegsberg B, Kanegsberg E. Standards Evolution, Controlled Environments. 2012: January.
9. ASTM Work Item WK31799, Standard Practice/Guide for Designing Medical Devices for Cleanability.
10. ASTM Work Item WK33439, Standard Practice/Guide for Standard test soils for validation of cleaning methods for reusable medical devices.
11. ASTM Work Item WK33660, Standard Practice/Guide for Validating Clean Lines for Medical Devices.
Barbara Kanegsberg and Ed Kanegsberg (the Cleaning Lady and the Rocket Scientist) are independent consultants in critical and precision cleaning, surface preparation, and contamination control. They are the editors of The Handbook for Critical Cleaning, Second Ed., CRC Press. Contact: firstname.lastname@example.org.
John J. Broad is a senior consultant at NAMSA, Irvine, Calif., and a specialist microbiologist with ASM. He is active in AAMI/ISO sterilization subcommittees. His publications include articles for Controlled Environments and a chapter in The Handbook for Critical Cleaning, Second Ed. Contact: email@example.com.
This article was published in the July/August 2012 issue of Controlled Environments magazine, pp. 34-36.