20/20 Imaging Insights

No Wonder Why TEE Probe Leakage Testing Was Never Performed

BY TED LUCIDI

Back in the early 2000s, when I was an in-house service engineer supporting diagnostic ultrasound, I was asked to begin performing leakage testing on TEE probes. I serviced the systems, arranged for replacement probes and was very familiar with performing leakage testing on medical devices. I had no idea of how to perform leakage testing on a TEE probe and really wasn’t that familiar with or comfortable with handling TEE probes either. Fast forward to 2022, and the process of performing leakage testing on TEE probes may still seem unfamiliar to some HTM teams. I thought it prudent to discuss the process and help raise understanding into why the testing is performed and awareness to some of the challenges faced by end-users.

General leakage testing began as a result of consumer advocates making claims that electrocutions were occurring during routine hospital procedures, and in the 1970s the U.S. government enacted codes and regulations to minimize such opportunities. It’s been shown that for micro-shock to actually occur, multiple devices need to be simultaneously electrically unsafe, and a very, very unique scenario must exist. Some argue the irrelevance of performing routine leakage testing as part of every PM procedure, but that won’t be presented here. I think that we’d all agree that leakage testing should be performed at key points in a device’s lifecycle.

The concept of TEE probe leakage testing is related to identifying a break in the probe’s physical integrity (on the distal tip, bending section, or insertion tube) that could allow a micro-shock condition to present itself. Given the statistical probability of a micro-shock scenario not occurring, there are other, far more important, reasons to perform TEE probe leakage testing.

If a break in a TEE probe’s physical integrity exists, the cut, hole, or void could 1) harbor bacteria leading to cross-contamination, or 2) allow harsh chemical disinfectants to enter the probe and be subsequently discharged, from the probe into a patient, during its next use. I’ll cite a third reason later. I think that you’d agree that these two scenarios have a much higher probability of occurring than micro-shock. You may find it interesting that one OEM has changed its use of the term TEE leakage testing to bite-hole testing to be more descriptive. The end result is whether it’s called leakage testing, bite hole testing, or something else, frequent “physical integrity” testing is of great importance as part of the usage cycle of TEE probes. It’s imperative that end-users perform this testing between each use and have a process in-place to address failures. It is not a task to be performed annually, semi-annually, or even monthly by the HTM team.

Back in the early 2000s, TEE probe leakage testing required the use of an electrical safety analyzer and that the probe be connected to the ultrasound scanner. A special tube or basin was needed, as well as water having minimal conductivity (distilled water could not be used). Service and operator manuals didn’t suggest testing intervals other than during a PM or on an as-needed basis (when users identified an item of concern. What’s that? Definition please). Following the leakage testing procedure from several OEMs, and those in IEC 60601, there are two methods of testing probe leakage, Source and Sink. Each has a different procedure, and each has different pass/fail criteria, and the pass/fail criteria varied by probe type (Type CF or Type BF, What’s that? Help me understand.). Between the specialized equipment, out-of-the norm procedure, and varying testing methods and cryptic criteria, the whole process was extremely cumbersome and intimidating. No wonder why few ever performed this testing in the health care environment.

Enter the mid-2000s, and the process became much easier. Dale Technology created the first universal off-the-shelf

Ted Lucidi

leakage tester for TEE probes. Siemens developed their own earlier, but it only allowed connection of Siemens probes. The Dale 800 could be used universally, given the use of the correct accessory adaptor. The main benefits were that leakage testing could now be: 1) performed without the scanner, 2) performed without an intimidating electrical safety analyzer requiring technical aptitude, and 3) could now enable testing by end-users. The industry began to recognize the importance of frequent TEE probe leakage testing and the need for end-users to be doing it. Now, multiple suppliers offer leakage test meters.

In 2016, the Intersocietal Accreditation Commission (IAC) began requiring its accredited hospitals to perform leakage testing on all TEE probes between each procedure. They also require that test results be logged for each probe, between each use. So far, The Joint Commission has not yet required it, and so many facilities still do not perform it. Our data suggests that less than 50% of all facilities, using TEE probes, have a comprehensive process to identify and mitigate breaks in physical integrity of TEE probes. It’s no surprise that about 70% of all TEE probes sent in to Innovatus have failed as a result of fluid invasion due to a break in physical integrity.

A third reason for performing TEE probe leakage testing is to minimize costly catastrophic TEE probe failures as a result of fluid invasion. If there is a break in physical integrity, and the probe is immersed in disinfectant or processed in an automated system, the chemical disinfectant will flood the probe. One or more problems might occur: 1. As above, the fluid entering the probe could be discharged into one of the subsequent patients; 2. Once inside a TEE probe, chemical disinfectants can corrode the electronics in a matter of hours, causing massive damage; or 3. If a fluid invaded probe is energized on a scanner, the probe’s sensitive electronics might be irreparably damaged. The scanner itself might also require a costly repair.

Next month, we’ll continue by presenting some common problems encountered by our customers when using off-the-shelf TEE probe leakage testers. Innovatus provides technical support on the products that we service (ultrasound probes and MRI coils), and many tech support calls are related to this topic. We’re here to assist you and your customers with this topic and others. For questions, assistance, or more information, please reach out to info@innovatusimaging.com If you have a TEE probe that has failed the leakage test, we can help! We have some of the strongest repair capabilities on standard and 3D TEE probe models.

For more information, email at TedL@innovatusimaging.com or visit www.innovatusimaging.com/ultrasound.

—Ted Lucidi, CBET, is a clinical, technical and commercial specialist at Innovatus Imaging.

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