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The new Invisio^{®} DUR-D ‘chip-on-the-tip’ digital flexible ureterorenoscopes: evaluation of changes in physical properties over time

Tamer El-Husseiny, Junaid Masood, Dimitrios Karamanolakis, Malcolm Birch and Noor Buchholz

Background & purpose: Flexible ureterorenoscopes (fURSs) have become an essential tool in endourological practice. In 2006, a new generation of digital fURSs (Invisio® DUR-D, ACMI, USA) with new optical technology was introduced. We have compared both light intensity and deflection angles, with and without indwelling instruments, between identical scopes of different number of uses to evaluate changes in physical properties over time.
Materials & methods: On three identical Invisio DUR-D digital flexible ureteroscopes of different usages we measured and compared the light intensity. Measurements were taken three times each with the ureteroscopes in straight position and maximum upwards and downwards deflection, respectively. The first scope was brand new; the second had been used 30 times while the third had been used 44 times. We also measured and compared the deflection angles without and with widely used accessory instruments inside the working channel in four identical scopes after 0, 10, 30 and 44 uses, respectively.
Results: Light intensity for each scope showed slight differences in relation to deflection angles, but it remained stable after many uses. By contrast, the deflection angle is shown to deteriorate with instruments inside the working channel. This is relatively independent of the type of microinstrument used, but the decrease is directly proportional with advanced age of the scope in terms of uses.
Conclusions: As an advantage over earlier generation scopes, light output remains constant due to the absence of the fragile low-resolution fiberoptics. Similarly to the earlier generation scopes, there remains a decrease in deflection capability over time with the new Invisio DUR-D digital fURSs.