The aim of this bench study conducted by scientists at the Center for Devices and Radiological Health of the US Food and Drug Administration (FDA) was to characterize virus transmission through otolaryngologic endoscope sheaths in which a hole or tear had been made with an excimer laser or acupuncture needle. EndoSheath® Technology (n = 22) with a hole or tear ranging from 2 to 84 μm were applied to an endoscope, which was then submerged in a high-titer virus suspension (108 viruses/mL). The inside of each EndoSheath® barrier and the endoscope on which it had been placed were then rinsed separately to determine the amount of any virus that had penetrated through the hole.
A sequential test was also conducted. In this experiment, a virus challenge was first performed outside an EndoSheath® disposable in which a 30-μm hole was created before it was applied to an endoscope. The EndoSheath® Technology was then removed from the possibly contaminated endoscope, and a second EndoSheath® barrier, in which a 20-μm hole had been made in the same location as the 30-μm hole in the first EndoSheath® disposable, was placed on the endoscope. Another virus challenge was conducted to determine whether any virus would pass outward through the second sheath.
The fi rst experiment found that small volumes of virus-containing fluid penetrated through the holes or tears in the EndoSheath® Technology and that up to 45% of passed virus particles could be recovered from the endoscope after removal of the EndoSheath® Technology. In the sequential test, virus was found on the second disposable barrier in only one case. Most important, according to the researchers, no virus was found outside the second sheath.
The FDA researchers recommended that an endoscope reprocessing step be combined with use of disposable sheaths. They also said, however, that their data indicated that the step need not be high-level disinfection. Instead, they concluded that meticulous cleaning of an endoscope followed by intermediate-level disinfection should provide a safe instrument for otolaryngologic endoscopy.