What is the overall purpose of AAMI ST108?

AAMI (Association for the Advancement of Medical Instrumentation) Standard ST108 defines levels of water quality suitable for various stages of medical device processing – to make the devices safe for patients. The standard applies to water provided to devices such as automatic endoscope reprocessors (AERs), ultrasonic sterilizers, autoclaves, and local steam generators.

ST108 became an ANSI standard on August 4, 2023. It may become a requirement of other standards (Joint Commission EC.02.05.02) and for product manufacturer warranties.


Who Manages AAMI ST108 Compliance in Your Facility?

AAMI ST108 indicates that the medical device processing water quality requirements should be managed by the same team that oversees the water management program (WMP) required by Joint Commission Standard EC.02.05.02 and CMS QSO17-30. ST108 suggests that the team include a senior leader (“executive sponsor”), water treatment specialist, and personnel from facilities engineering, infection prevention, medical device processing, clinical engineering, and surgery.


What testing is required by AAMI ST108?

ST108 requires a lot of testing! “Utility water” used for washing devices, steam condensate used for sterilization, and “critical water” used for reprocessing, sterilizing, and rinsing must be tested for a total of about 18 parameters including:

  • Microbial parameters (e.g., heterotrophic bacteria; endotoxins)
  • Chemical parameters (e.g., dissolved minerals; metals)
  • General water quality parameters (e.g., conductivity, pH, total organic carbon, turbidity)


How can AAMI ST108 Testing be Streamlined?

Testing 18 parameters at points of use (POUs) – in utility water, critical water and steam – is no small task. To reduce the time and cost burden, plan carefully and automate as much as possible.

Sensors can be used to automate the testing of several parameters (see Table 4 of ST108) including pH, conductivity, and turbidity.

Tests performed by laboratories can be semi- automated if the lab is integrated with documentation and reporting software (e.g., LAMPS). Samples are collected and sent to the lab for tests of one or more parameters per sample. With an integration, the sample data is sent electronically to the lab directly from the software chain of custody that is filled out while collecting the samples. After the lab finishes the analyses, the test results are reported electronically, directly into the software.

Other non-microbial parameters can be tested with handheld or tabletop devices. The test results will ideally be entered in the same software (e.g., LAMPS) that processes the sensor data and lab test results so that the ST108 reports show results from all the tests.

Tests with handheld devices may have a lower initial cost than tests with sensors or by labs but a higher ongoing cost for consumables and replacements. The higher labor burden may be the biggest cost of the manual tests.


What is needed to show compliance with AAMI ST108?

Expectations for hospitals will likely become clearer in 2024 after AAMI finishes and publishes its “Guidance on Healthcare Implementation and Use of AAMI ST108” (TIR119/Ed.1. Any updates of CMS QSO17-30, Joint Commission EC.02.05.02, or DNV requirements will also clarify expectations. For example, facilities need clarification on reporting requirements, the number of points of use (POUs) to test, and terms such as “frequently” and “more frequently.”

What are the key steps to getting started with AAMI ST108 compliance?
Some key steps in getting started with AAMI ST108 include:

  1. Identify points to test.
  2. Find vendors for sampling, lab, and remediation services.
  3. Set up software needed for entering, storing, and reporting test results.
  4. Upgrade equipment as necessary.

David Swiderski is the Senior Technical Strategist at HC Info.

If your water management program is in LAMPS, see Training Note 3.008 about using LAMPS for ST108 data.

What suggestions should be added to this article about complying with AAMI ST108? Please comment below.

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