Ali H Aldoukhi1, William W Roberts2, Timothy L Hall3, Joel M H Teichman4, Khurshid R Ghani5. 1. Division of Endourology, Department of Urology, University of Michigan, Ann Arbor, MI. Electronic address: ahaldouk@med.umich.edu. 2. Division of Endourology, Department of Urology, University of Michigan, Ann Arbor, MI; Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI. 3. Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI. 4. Department of Urologic Sciences, University of British Columbia, Vancouver, British Columbia, Canada. 5. Division of Endourology, Department of Urology, University of Michigan, Ann Arbor, MI.
Abstract
OBJECTIVE: To assess low and high power settings for the popcorn technique, and relationship of laser fiber-to-stone distance and calyceal size on submillimeter fragmentation. Our in vitro findings may help guide strategies to improve a dusting technique for ureteroscopy. METHODS: BegoStones were fragmented in small (127 mm3) and large (411 mm3) sized bulbs to simulate calyces, using a 120 W Ho:YAG laser. A 242 μm fiber was introduced through a ureteroscope mounted to a 3D positioner with its tip located at 0 or 2 mm distance from the stones. 20 W [1 J × 20 Hz, 0.5 J × 40 Hz] and 40 W [1 J × 40 Hz, 0.5 J × 80 Hz] settings were assessed, including short pulse and long pulse modes. Total energy delivered was constant at 7.2 kJ. Primary outcome was percentage of stone mass converted to fragments <1 mm. High-speed imaging was performed to study stone movement and/or fragmentation. RESULTS: For all settings, popcorn lithotripsy yielded more submillimeter fragments when performed with the fiber positioned on the stone compared to 2 mm from the stone (P <.05). Distribution of submillimeter fragments was higher when utilizing high frequencies regardless of pulse energy. At 2 mm distance, popcorning was more effective in the small model (P <.05). At 2 mm distance, short pulse was superior to long pulse. Video analysis showed fragmentation did not occur when stones collided with each other. At 80 Hz/2 mm distance, only 17.5% of pulses impacted fragments. CONCLUSION: Popcorn technique is more effective when the fiber is directly in contact with stone, and when performed in a small calyceal model. Utilizing settings with higher frequencies may improve dusting outcomes.
OBJECTIVE: To assess low and high power settings for the popcorn technique, and relationship of laser fiber-to-stone distance and calyceal size on submillimeter fragmentation. Our in vitro findings may help guide strategies to improve a dusting technique for ureteroscopy. METHODS: BegoStones were fragmented in small (127 mm3) and large (411 mm3) sized bulbs to simulate calyces, using a 120 W Ho:YAG laser. A 242 μm fiber was introduced through a ureteroscope mounted to a 3D positioner with its tip located at 0 or 2 mm distance from the stones. 20 W [1 J × 20 Hz, 0.5 J × 40 Hz] and 40 W [1 J × 40 Hz, 0.5 J × 80 Hz] settings were assessed, including short pulse and long pulse modes. Total energy delivered was constant at 7.2 kJ. Primary outcome was percentage of stone mass converted to fragments <1 mm. High-speed imaging was performed to study stone movement and/or fragmentation. RESULTS: For all settings, popcorn lithotripsy yielded more submillimeter fragments when performed with the fiber positioned on the stone compared to 2 mm from the stone (P <.05). Distribution of submillimeter fragments was higher when utilizing high frequencies regardless of pulse energy. At 2 mm distance, popcorning was more effective in the small model (P <.05). At 2 mm distance, short pulse was superior to long pulse. Video analysis showed fragmentation did not occur when stones collided with each other. At 80 Hz/2 mm distance, only 17.5% of pulses impacted fragments. CONCLUSION: Popcorn technique is more effective when the fiber is directly in contact with stone, and when performed in a small calyceal model. Utilizing settings with higher frequencies may improve dusting outcomes.
Authors: Brandon A Levin; Ali H Aldoukhi; Kristian M Black; Timothy L Hall; William W Roberts; Khurshid R Ghani Journal: Lasers Med Sci Date: 2021-01-09 Impact factor: 3.161
Authors: Adam D Maxwell; Brian MacConaghy; Jonathan D Harper; Ali H Aldoukhi; Timothy L Hall; William W Roberts Journal: J Endourol Date: 2019-01-29 Impact factor: 2.942
Authors: Ray Yong; Gregory E Tasian; Kate H Kraft; William W Roberts; Adam Maxwell; Jonathan S Ellison Journal: Can Urol Assoc J Date: 2022-03 Impact factor: 1.862