Question: With device cleaning gaining greater attention, how should we think about the difference between manual and mechanical cleaning validation?
Answered by Gary J. Socola, President, HIGHPOWER Validation Testing & Lab Services: In today’s world of reusable medical device reprocessing, proper cleaning protocols have become a major focus in light of the recent superbug outbreaks associated with improperly cleaned duodenoscopes. This issue brought device cleaning to the forefront of healthcare decision making in the U.S. and abroad. The duodenoscope issue has led to heated debates at standards meetings concerning the use of High Level Disinfection (HLD) or terminal sterilization for these types of medical devices in the future. It has also led to a large postmarket evaluation of the cleaning methods of the main manufacturers of these devices by FDA.
Now, we find ourselves faced with a worldwide pandemic (COVID-19), which started last year in Wuhan, China, and has spread around the globe. This pandemic has brought certain shortcomings to light in our industry concerning the availability of Personal Protective Equipment (PPE), such as N95 masks, face shields, etc. As healthcare practitioners, we have the obligation to ensure patient safety. Therefore, hospitals around the globe began to ask whether these single-use items could be safely and properly reprocessed for reuse under the dire circumstances in their healthcare facilities.
Welcome to the world of 21st century medical device reprocessing. There’s an old saying in our industry (medical device validation) that goes something like this: “If you can’t clean a device, you can’t guarantee that it will be sterile after processing.” This was not only a true statement back in 1879, in the lab of Louis Pasteur, but it’s still a true statement today. Just like we experienced the debate over HLD or terminal sterilization of complex endoscopes post cleaning, we now have a similar debate concerning reusable medical device cleaning. Which is better, manual or mechanical cleaning? The answer just might surprise you.
Standardizing Medical Device Cleaning
HIGHPOWER Validation Testing & Lab Services has been validating the cleaning, packaging and sterilization of reusable medical devices for over 30 years. In these three decades, we’ve seen many changes in the validation of reusable medical device cleaning studies. Some are regulatory driven, others driven from a legal aspect and still others internally driven by orthopedic device manufacturers themselves. FDA and the Association for the Advancement of Medical Instrumentation (AAMI) have been working through the standards process to upgrade the U.S. standards that device manufacturers and validation laboratories like HIGHPOWER rely on.
A number of years ago, a technical information report (TIR30) was developed by AAMI’s Cleaning of Reusable Medical Devices Working Group under the auspices of the AAMI Sterilization Standards Committee. It was titled TIR30 – A compendium of processes, materials, test methods, and acceptance criteria for cleaning reusable medical devices, and it has been the main go-to document for reusable medical device cleaning validations with another AAMI document, TIR12 – Designing, testing, and labeling reusable medical devices for reprocessing in health care facilities: A guide for medical device manufacturers. Currently, both of these documents are undergoing significant revisions at the standards level through AAMI.
TIR30 is transitioning from a TIR to an actual standard, which will eventually be known as ST-98. Conversely, TIR12 will remain a technical information report, but its transformation will include, for the first time in the U.S., a handful of standardized cleaning procedures for device manufacturers to consider for use with their devices. Both ST-98 and TIR12 have not been finalized but when they are, a simpler pathway for device cleaning studies will be available.
Manual vs. Mechanical Cleaning
But the question remains—which is better, manual or mechanical cleaning? The answer is, it depends. There are just so many variables in play for both cleaning methods. But what we do know is that in order to remove contamination between patient uses, a thorough cleaning is paramount for proper device reprocessing. And, it assures that subsequent further device processing, whether via HLD or sterilization, is successful.
Many device manufacturers offer automated (mechanical) and/or manual cleaning methods in their instructions for use (IFU). Each method has its own set of limitations, however. During manual cleaning, we must deal with the variability of the human interaction, the brushes used, the duration of brushing, and which detergent is used in the process. During mechanical cleaning, we have a host of cleaning detergents to choose from, we have a number of phases that we can include or not include in the mechanical cleaning process, and we can select a range of hot or cold temperatures for the different phases we have programmed in the cleaning process itself.
Let us not forget that the majority of mechanical cleaning IFUs have a manual pre-cleaning step within them, so we have the human interaction as a variable once again, but this time on the mechanical side (if a manual pre-clean is included in the device’s IFU).
Recently, HIGHPOWER Labs was asked to focus our attention on reviewing data compiled from a statistically valid number of studies where the same device was cleaned using both the automated and manual cleaning processes following worst case soiling methods. The devices and soiling techniques themselves were constant for each data point.
Positive control devices, inoculated with a protein analyte containing artificial test soil, were analyzed via the Micro BCA method to document their residual protein level. Test devices were soiled in the same manner and processed through either the manual or mechanical cleaning method as recommended by the device manufacturer.
Following cleaning, the test devices were extracted and assayed via the Micro BCA method for the residual protein levels that were remaining on the devices. Quantitative methods were used to evaluate the cleaning efficacy of both methods, and showed that the mechanical (automated) cleaning process provided a lower standard deviation (SD) and a more reproducible end result than devices cleaned using the manual cleaning method, albeit only slightly. The average level of residual protein remaining on the manually cleaned devices was 0.31 ug/mL, resulting in an SD of 0.34, whereas the average level of residual protein remaining on the mechanically cleaned devices was 0.22 ug/mL, resulting in an SD of 0.30.
Mechanical and Manual Protein Level Post Cleaning
This is a retrospective review of data from eight prior client studies that was based on the clients’ manual and mechanical cleaning IFU. The eight studies included a total of 125 individual medical devices cleaned using both methodologies. The data reviewed from these studies indicates a better, more reproducible cleaning process occurred on the devices cleaned using the mechanical cleaning procedure.
However, further study under more tightly controlled conditions should be undertaken to make broader claims concerning the efficacy of mechanical and manual cleaning method comparisons of critical and semi-critical medical devices. This study would include the use of the same detergent and manual/mechanical cleaning parameters, a uniform level of soil placed on both the manual and mechanical method test devices, and include multiple complex devices from multiple manufacturers with differing mechanical and manual cleaning IFUs.
The analysis presented here shouldn’t necessarily be interpreted as the devices were cleaner by the mechanical means of processing, but rather the results from the review were more reproducible when using the mechanical process when compared to the same devices cleaned in the manual cleaning process.
In closing, orthopedic device manufacturers need to validate either a manual or mechanical cleaning process (savvy manufacturers do both) when seeking FDA 510(k) clearance. Any device manufacturer has the liberty of adding more steps to either their manual or mechanical cleaning process (for a specific device) during validation, and by altering the variables discussed earlier, can make either the manual or mechanical cleaning process more robust than the other.
For this reason, it’s better for an orthopedic device manufacturer to set goals based on the reproducibility of the cleaning validations results (as long as they are at or below the tests defined acceptance criteria) and not get caught up in which method may provide a lower level of “clean.”
Gary J. Socola is Founder and President of HIGHPOWER Validation Testing & Lab Services Inc. Mr. Socola has more than 35 years working in the medical device industry, acting as technical lead, quality, regulatory or subject matter expert in the development of class II medical devices, their use within the industry, their required validation and subsequent reprocessing instructions.