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20/20 IMAGING INSIGHTS No Wonder Why TEE Probe Leakage Testing Was Never Performed BY TED LUCIDI
Ted Lucidi
B
ack 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
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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
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