Medical Design Briefs - December 2021 - 36

Medical Device Cleaning Validations
justification for the sample size to
ensure that
delays.
Considerations for Manufacturers and
Test Labs for Cleaning Validation Studies
When planning a cleaning validation
Soiling of medical devices for reprocessing cleaning validations. (Credit: Eurofins)
soil recovered is determined for each
extraction. The extraction efficiency
compares the testing result of the first
extraction to the sum of all testing
results for all extractions performed.
Extraction Efficiency Requirements
In addition to the need to validate the
extraction method, ST98 states that the
extraction efficiency from the validation
of the method should be greater than 70
percent. When validating using spike
recovery, the ratio of the amount of soil
recovered to the amount of soil added
should be greater than 70 percent. If validating
using exhaustive extraction, the
ratio between the testing result of the
first extraction and the sum of all testing
results for all extractions performed
should be greater than 70 percent.
A higher extraction efficiency equates
to a better extraction method. ST98
allows for the use of an extraction
method that yields a lower efficiency;
however, its use must be justified.
The lab performing the cleaning validation
must ensure that this new consideration
is documented in the validation.
The lab must establish controls that will
provide the reproducibility needed for a
seamless submission.
Total Organic Carbon Acceptance
Criteria
AAMI TIR30:2011 offers some, but
not all, acceptance criteria for endpoint
tests. Total organic carbon (TOC) is not
included. Currently, TOC acceptance
criteria for cleaning validations derives
36
Cov
from various studies on cleaning validations.
The new AAMI ST98 includes a
list of all currently relevant acceptance
criteria for endpoint tests, including
TOC. ST98 defines the acceptance criteria
for TOC as ≤12 µg/cm2.
Justification of Sample Size
When performing a cleaning validation
study, the number of devices tested
and the number of results generated are
an important factor in showing that the
device is clean. AAMI ST98 states that
the number of devices tested is to be justified
within the cleaning validation. The
new standard also provides guidance on
the conditions to be achieved in order to
prove that the number of devices tested
was sufficient. These conditions include:
1. A minimum of three data points are
generated per each endpoint test.
2. All data points must be within the stated
acceptance criteria, within ST98,
for that endpoint test.
3. The variation of data points between
samples must be determined.
The acceptability of the variation is
determined by calculating the standard
deviation of the set of data points. This
value is then added to the highest data
point; the result must not exceed the
acceptance criteria for that endpoint
test. If this value exceeds the acceptance
criteria, the number of devices tested
was not sufficient.
It is important to ensure that this new
consideration is documented within the
validation. The lab performing this
should document all results and offer
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ToC
study, the testing laboratory chosen to
perform the study should be knowledgeable
in the regulations surrounding the
study. It is important that the lab understands
all current and upcoming regulations,
so that the device being validated
is tested appropriately. Additionally, the
lab should have testing equipment similar
to what is used in a clinical or hospital
setting. The end users of the device
must be able to replicate the cleaning
process when using the device.
Finally, the lab should be agile and
competent to troubleshoot any obstacles
as they arise. A team of scientists that have
a myriad of experience performing cleaning
validations on all types and categories
of medical devices will help keep the validation
on track and completed in an efficient
manner. A global network of re -
sources is advantageous when performing
cleaning validations on any categories
of devices, but it is also beneficial if the
device will be used in different countries.
The upcoming AAMI ST98 standard
will help medical device manufacturers
and scientists in developing and testing
devices that will undergo cleaning validations.
The detail provided in ST98 on
validation of extraction methods, extraction
efficiency requirements, TOC ac -
ceptance criteria, and justification of
sample size helps to ensure that the
cleaning validation meets regulatory
requirements. AAMI ST98, along with
the aforementioned considerations for
test labs, will help the continuity of the
cleaning validation against any setbacks
and ensure that it is completed successfully.
The considerations detailed in
ST98 are critical to a successful cleaning
validation and confirm the cleaning protocols
on medical devices to help ensure
patient safety.
Reference
1. AAMI TIR30:2011 - A compendium of
processes, materials, test methods, and
acceptance criteria for cleaning reusable
medical devices.
This article was written by Lori Graybill,
Principal Scientist, Microbiology, Eurofins
Medical Device Testing, Lancaster, PA. For
more information, visit http://info.hotims.
com/79420-342.
Winter 2021 Resource Guide
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