PD18-11 COMPARISON OF AN ELECTRIC PULSE LITHOTRIPTER TO THE HOLMIUM LASER: STONE FRAGMENTATION EFFICIENCY AND IMPACT ON FLEXIBLE URETEROSCOPE DEFLECTION AND FLOW

Abstract

INTRODUCTION AND OBJECTIVES: A new intracorporeal lithotriptor uses a nanosecond duration electrical discharge through a flexible coaxial probe to endoscopically fragment urinary stones. This device was compared to a holmium laser with regards to stone fragmentation efficiency and their impact on flexible ureteroscope deflection and flow of irrigation. METHODS: Using a custom bench model, stone fragmentation efficiency of the Nano-electric Pulse Lithotriptor (NPL, Lithotech Group, Israel) was evaluated with a begostone (mixture 5:2) confined under 0.9% normal saline atop sequential mesh sieves. Two NPL probe sizes (2.0 and 3.6F) and two holmium laser fibers (200 mm and 365mm) were evaluated using 6mm begostones. Time to first break, time to complete break (all fragments <3mm), and overall fragment sizes were measured. Ureteroscope deflection was tested in 5 new 4th generation flexible ureteroscopes, with an empty channel followed by placement of a 2.0F NPL probe, a 2.4F NPL probe, a 200mm laser fiber, and a 1.9F wire basket. Ureteroscope irrigation flow was measured using normal saline at 100 cm, with an empty channel and then with a 2.0F NEP probe, a 200mm laser fiber, and a 1.9F wire basket. RESULTS: The 2.0F NPL showed improved stone fragmentation efficiency compared to the 200mm laser (86 mg/min vs. 52 mg/min, p 1⁄4 0.014) as did the 3.6F NPL vs. the 365mm laser (173 mg/min vs. 80 mg/min, p1⁄40.05). The NPL created more 1-2 mm fragments, while the laser created more dust (< 1 mm fragments); the difference was more pronounced between the larger NPL and laser probes. In the 5 ureteroscopes tested, ureteroscope deflection was reduced by an average of 3.75 with the 2.0F NPL probe and 22.25 with the 2.4F NLP probe (compared to 5.25 with the laser and 2.75 with the basket). Irrigation flow through the ureteroscope was 36.5 ml/min on average, and was reduced to 18.3 ml/min with the 200mm laser fiber, and to 6.3 ml/min with the 2.0F NEP probe. CONCLUSIONS: The Nano-electric pulse lithotripter produces improved stone fragmentation efficiency as compared to the holmium laser. However the 2.0F and 2.4F NPL probes limit flow and the 2.4F probe limits ureteroscope deflection.