It looked like someone had taken a hammer to the surgical robot's plastic arm. But something else had caused the plastic to crack and craze: the disinfecting sprays and wipes the OR team was using to wipe down the surgical robot after each use. Over time, the disinfectant had degraded the integrity of the plastic. This is just one example of environmental stress cracking that the ECRI Institute, a medical product testing lab in Plymouth Meeting, Pa., is investigating.
Stress cracking occurs when the repeated use of "incompatible" chemical agents degrades the integrity of plastics. And it could be happening to the plastic components of such products as infusion pumps, positioning aids and vital-signs monitors without you even knowing, says Jaime Schlorff, senior project officer, health devices group, for ECRI.
"Any medical device that has a plastic component is susceptible," says Ms. Schlorff. "There are different kinds of plastics, and different cleaners are compatible with different kinds of plastics."
The process begins slowly, with early warning signs such as cracking and crazing, the latter of which appears as a crackling effect on the surface of some materials, caused by a network of fine cracks, says Ms. Schlorff. The phenomenon also has the potential to compromise patient care. ECRI listed it as one of the leading threats to healthcare safety in its recent "Top 10 Health Technology Hazards for 2017" report. Given the sheer number of available cleaning agents — ECRI says 286 manufacturers make sprays and wipes intended for healthcare usage — Ms. Schlorff says the issue can be "a real hurdle" to overcome.
Device manufacturers are aware of the problem, and most do their best to use plastics that will resist common cleaners, but Ms. Schlorff says that "no one cleaner is safe for all plastics and no one plastic is resistant to all cleaners. Hospitals and surgery centers need to have multiple cleaners available. It's a challenge to make sure the clinical staff has the right cleaners available and are following the right instructions."
She suggests giving the clinical staff a thorough review of cleaning procedures for each piece of equipment, including a list of compatible/incompatible cleaners, which manufacturers can provide. Also, she advises inspecting various devices regularly to look for signs of cracking, crazing and other indications that the plastic parts of equipment may be breaking down or on the verge of failure.
"You need to have a cleaner that is safe to use with that specific device," says Ms. Schlorff. "Considering the different types of equipment and the many different types of cleaners, that can be a difficult strategy to implement. It's not as simple as wiping down a piece of equipment and making sure it's disinfected. It's a balancing act."