Point-of-Care Disinfection

GE introduces the new Trophon EPR transducer disinfection system, designed to minimize transducer damage and maximize safety and efficiency

Ultrasound transducers are generally reliable—unless damaged. And, unfortunately, damage is not uncommon. As many clinical/biomedical engineers know, the devices can be impaired when improperly transported or disinfected. Clinical engineering departments often tackle these issues through user education, but turnover, urgency, and accidents contribute to the need for continued efforts.

In a move intended to reduce damage from improper handling and disinfection, GE Healthcare, Waukesha, Wis, is now distributing the Trophon EPR, a complete transducer disinfection system developed by Nanosonics, Alexandria, Australia. Designed for use at the point-of-care, the system employs an innovative platform technology that disinfects the transducer—including shaft and handle—in 7 minutes.

“A lot of damage with the transducers or probes occurs around their sterilization because, as part of that sterilization process, you’re typically removing the devices from the machine, you’re transporting them to another part of the hospital, and you’re dipping them into a lot of chemicals people don’t want to deal with,” says Brian McEathron, general manager of GE Healthcare’s general imaging ultrasound unit. “If it’s done incorrectly, it can damage the probes or transducers.”

Damaging Diagnosis
Improperly working transducers can have a negative impact on the outcome of the exam. A white paper by G. Wayne Moore, at the time president and chief executive officer of Sonora Medical Systems Inc, Longmont, Colo, concludes that the “overall health of the array is critical to obtaining a high quality and efficacious ultrasound study and that the potential for misdiagnosis increases as array elements degrade.”¹

With modern transducer arrays commonly containing 128 elements, and some comprised of more than 288, the fact that a small number of damaged components can mar performance means even slight impairment can have an impact. Moore’s team found that two consecutive dead elements in an array of 128 have a noticeable impact on the acoustic beam propagated into the body and that four or more dead or degraded elements in an array had a significant negative impact on the acoustic beam.¹ This resulted in reduced resolution, decreased depth of penetration (for both Doppler and imaging), image “blooming” at depth, a higher overall noise floor in imaging modes, and both peak velocity errors as well as directional ambiguities in spectral displays.¹

Damaging Safety
Degradation can potentially occur during mishandling, whether through an accidental drop or collision or through improper disinfection procedures. However, with the risk of hospital-acquired infections ever present, disinfection is key to safe and quality care.

The Centers for Disease Control and Prevention has classified ultrasound probes as a critical item, conferring a high risk for infection if contaminated with any microorganism and recommended high-level procedures to ensure proper sterilization. However, common disinfection methods have drawbacks.

Many involve chemicals that are hazardous to humans and, therefore, often require costly special handling equipment, such as ventilation hoods or neutralizing chemicals. These chemicals can also damage transducer elements, immediately if a leak exists in the protective cover. Over time, they may weaken the membrane, stain the material, and/or increase the likelihood of breakage. And even then, the system may not sterilize the handle (which does not get immersed).

Preserving Performance
The Trophon EPR eliminates some of these challenges through use of a unique platform. The Sonex-HL, a Nanosonics proprietary solution, is nebulized within the closed system into a highly concentrated hydrogen peroxide vapor, which is distributed through the chamber quickly and evenly. The high-level disinfection vapor spreads like a gas but retains liquid properties, completely immersing the precleaned transducer, including its handle.

When the cycle is complete, chemical indicators change colors to validate disinfection has occurred. Cartridge replacement is clean and easy through a side door on the system; each cartridge has enough biocide for multiple disinfection cycles.

Operators are exposed to less risk both because the system is closed (eliminating chemical exposure) and because the by-products are environmentally friendly: small quantities of water and oxygen are generated. There is no need to handle and dispose of dangerous waste or residue.

The system’s point-of-care design and 7-minute turnaround time have also been developed with efficiency in mind. “The amount of damage caused by this sterilization process is greatly minimized and the turnaround time for getting probes sterilized is greatly enhanced. Hopefully, this technology will eliminate a lot of the bad sterilization processes hospitals have to implement these days,” McEathron says.

References:

1) Moore GW. The effect and mechanisms of ultrasound transducer degradation on the quality and clinical efficacy of diagnostic ultrasound examinations. Available at http://www.ids-healthcare.com/common/paper/paper_59/the%20effect%20and%20mechanisms.htm. Accessed on December 29, 2011.