'Trust but verify': The importance of sonic cleaner verification

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The ultrasonic cleaner is an important piece of medical equipment that, when working properly, is one of the best ways to thoroughly clean medical instruments. But, as with any medical device, healthcare organizations need to take proper steps to ensure ultrasonic cleaners are in good working order.


Stephen Kovach, director of clinical education with Healthmark Industries Company, explained during a May 23 webinar the ins and outs of sonic cleaning, including how ultrasonic cleaners function, key factors that affect how well the machine performs and how organizations should test the device's functionality. The webinar was sponsored by Healthmark and hosted by Becker's Healthcare.

Basics of sonic cleaning

Ultrasonic cleaners clean by a process called cavitation — tiny bubbles created by the machine implode, pulling bioburden and other debris from surface of the instrument into the cleaning solution.

Mr. Kovach offered five basic tips as to how to use an ultrasonic cleaner most efficiently and effectively to maximize its cavitation power.

1. Use detergent specifically designed for ultrasonic cleaners. This is important because the "detergent decrease surface tension within the solution and then that helps the cavitation process," he said.

2. Change the solution when the detergent is visibly soiled, or at least once or twice a shift. As this can be subjective, he urged workers to follow the instructions for use for both the detergent and the ultrasonic machine. If the solution is dirty, it can impede the ultrasonic's cleaning power.

3. Don't use plastic trays. Doing so will absorb cavitation energy.

4. Load the instruments properly. "If you just throw the instruments in there and don't spread them out [and] distribute the weight appropriately … you will not get effective cleaning," he said.

5. Separate instruments by metal type. "Don't mix metals," he said. He also warned some metals are not suited to go into an ultrasonic cleaner.

More generally, he said everyone should follow the cleaner's original instructions for use and preventative maintenance agreement.

Verification process

Several standards and guidelines — like Joint Commission guidelines and AAMI ST79 — support verification of sonic cleaners, and Mr. Kovach said many machines aren't working at their maximum capacity, but people fail to notice. He said more than half of the devices he tests fail Healthmark's efficacy tests.

"Hopefully everyone is doing some type of cleaning verification," he said. "You must trust, but verify."

Several steps in the sonic cleaning process can be verified, including water temperature, solution dilution and water quality.

When it comes to verifying the cleaning process, TOSI® is the best option to use over other tests. The test being used should be a surrogate device that represents the type of soil being cleaned as well as the design of the instrument, Mr. Kovach said.

Separate from cleaning, cavitation in particular needs to be verified, as it is not easy to visually observe failure of a sonic device, Mr. Kovach said. "Just hearing it making a [humming] sound is not enough, or seeing some ripples in the tank, that is just not enough."

Monitoring devices for detecting cavitation are commercially available. Many are subjective, such as the foil test. In addition to being subjective, the foil test often has complicated, specific instructions to follow and can leave aluminum foil residue behind in the tank. "[It's] very, very subjective, but it is something you can use," he said of the foil test.

The Sonocheck™ is less subjective than the foil test and has been verified to check cavitation.

To ensure this important step of the cleaning process is in good working order and to keep patients safe, hospitals need to verify that their reprocessing equipment is working properly.

To view a recording of the webinar on YouTube, click here.

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