Introduction

1. Effects of Holmium:YAG Laser Energy Settings on Fiber Tip Degradation Zachariah G. Goldsmith, Samarpit Rai, Andreas Neisius, Gaston M. Astroza, Agnes J. Wang, Muhammad W. Iqbal, W. Neal Simmons, RamayYaacoub, Nicholas J. Kuntz, Glenn M. Preminger, Michael E. Lipkin Division of Urologic Surgery VA and Duke University Medical Centers - Durham, North Carolina, USA Introduction Hypothesis The operative efficiency of laser lithotripsy is dependent upon stone fragmentation, as well as detractors to efficiency, including stone retropulsion, and fiber tip degradation or “burnback.” Tip degradation can necessitate intra-operative fiber re-stripping during laser lithotripsy which can prolong operative times. Tip degradation is dependent upon energy source settings. Constant Contact Setup Methods • Bench-top model was developed which maintains a constant contact of the fiber with the Begostone, by applying a constant gravity-dependent pressure. • 200 μM Flexiva™ fibers (Boston Scientific) • Cylindrical Begstone phantoms • 100 W LumenisVersaPulse™ PowerSuite® Holmium Laser energy source • Various pulse energy and frequency settings were transmitted for each lithotripsy trial. • Fiber length was measured before and after lithotripsy to determine amount of tip degradation. • Each setting was repeated for 5 trials. • Levels of tip degradation were compared using ANOVA. Sliding Chamber Counter Weight Laser Fiber Saline Bath BegoStone Tip Degradation Energy Settings 0.2 * * P<0.001 0.15 inches 0.1 0.05 0 0.2J, 50Hz 0.5J, 20Hz 0.6J, 6Hz 0.8J, 8Hz 1J, 10Hz Conceptual Model Retropulsion Conclusions Fragmentation Efficiency Tip Degradation • Fiber degradation, like stone fragmentation, requires contact between the laser fiber and the stone. • Low energy settings are associated with no or minimal tip degradation. • The setting of 1.0J and 10Hz is associated with significant fiber tip degradation. Energy Settings