Evaluation of three methodologies for testing disposable ENT endoscope sheaths as viral barriers

Three methods to determine the barrier function of ENT endoscope sheaths we re evaluated: (1) the air deflation test, a candidate quality assurance tes t, compared differences in pressure between a test sheath and an intact one ; (2) a virus barrier test challenged with bacteriophage phi X174 outside t he sheath, with barrier penetration determined by rinsing inside and assayi ng for penetrated virus; (3) another virus barrier test challenged from ins ide, with virus penetration determined by assaying a collection/submersion solution. Sheaths with laser-drilled holes or tears generated by acupunctur e needles were tested. Five-mu m holes and larger were detected by air defl ation or inside virus challenge. Outside virus challenge could reliably det ect only 30-mu m holes. Tears of 35-mu m length were detected by inside vir us challenge, while all three tests detected 85-mu m tears. In addition, ai r bubbles during submersion detected and located 5-mu m holes and larger, s uggesting another quality assurance test.