title: Evaluation of endoscope sheaths as viral barriers.
abstract: OBJECTIVE
  Evaluate ENT endoscope sheaths as barriers to virus passage.
  
  
  METHODS
  "Defective" sheaths covering an endoscope were challenged with virus to determine how many virus particles could be recovered from the endoscope.
  
  
  METHODS
  Sheaths with small laser-drilled holes (2 to 30 microm) were challenged with high-titer virus suspensions (10(8) viruses/mL). The inside of the sheath and the endoscope were separately rinsed to recover any virus that penetrated through the hole in the sheath. In an attempt to assess the possible importance of holes in the sheaths, a sequential test was conducted with an initial virus challenge outside a defective sheath (30-micron hole in the sheath), after which the possibly contaminated endoscope was removed and inserted into a second defective sheath (with a 20-micron hole at the same location) to determine whether the contaminating virus would pass outward through the second sheath.
  
  
  RESULTS
  Small volumes of virus-containing fluid penetrated through the hole, e.g., 500 virus particles passed through one of three 30-microm holes. A significant fraction of those virus particles was occasionally found on the endoscope after removal from the sheath. Similar results were obtained with sheaths that had small tears (34-84 microm in length, from punctures with fine wires). Although some virus penetration could occur during the initial challenge contaminating the endoscope, no virus was detected passing outward through the second sheath.
  
  
  CONCLUSIONS
  Use of a sheath combined with intermediate level disinfection should provide a safe instrument for ENT endoscopy.
authors: U.S. Food and Drug Administration Center for Devices and Radiological Health, Rockville, Maryland 20852, USA. khb@cdrh.fda.gov
authors: K H
authors: KH
authors: Baker
authors: M P
authors: MP
authors: Chaput
authors: C R
authors: CR
authors: Clavet
authors: G W
authors: GW
authors: Varney
authors: T M
authors: TM
authors: To
authors: C D
authors: CD
authors: Lytle
mesh_terms: D004203:Disinfection / Q000379:methods*; D019723:Endoscopes / Q000821:virology*; D004866:Equipment Contamination / Q000517:prevention & control*; D005069:Evaluation Studies as Topic; D020704:Laryngoscopes