Evaluation of efficacy of novel optically activated digital endoscope protection system against laser energy damage

To evaluate the reliability and efficacy of a novel endoscope protection system (EPS) against direct laser energy damage.

We performed in vitro evaluations of a novel EPS prototype that uses optical feedback from the digital sensor of the DUR-D ureteroscope to terminate the laser energy on retraction of the laser fiber into the ureteroscope. We evaluated various speeds of retraction (0.5, 2.0, and 5.0 cm/s) in normal saline and various concentrations of indigo carmine and human blood. We also evaluated the protrusion distance at which shutdown occurred with the laser fiber cladding cleaved at 0, 3, and 5 mm from the end of the fiber. Twenty trials of each condition were performed.

In normal saline and blood dilutions of up to 10 g/L, the EPS worked with 100% efficiency for all trials. For blood dilutions of 10 g/L or greater and indigo carmine concentrations of 0.16 g/L or greater, the reliability of the EPS deteriorated. Lasers stripped of 0, 3, and 5 mm of cladding initiated shutdown at 2.9 +/- 0.13, 5.1 +/- 0.09, and 8.2 +/- 0.15 mm from the ureteroscope distal end, respectively (P <0.01). A single DUR-D ureteroscope was used for all trials and remained completely intact through 120 retractions of the active laser fiber into the channel.

In this evaluation, the novel EPS was highly effective and reliable. When using indigo carmine or high-density blood concentrations, the efficacy of the EPS was compromised. The EPS should be used to complement standard safe laser technique rather than to replace it.