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Understanding the Popcorn Effect During Holmium Laser Lithotripsy for Dusting.
Urology 2018; 122:52-57U

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.

Authors+Show Affiliations

Division of Endourology, Department of Urology, University of Michigan, Ann Arbor, MI. Electronic address: ahaldouk@med.umich.edu.Division of Endourology, Department of Urology, University of Michigan, Ann Arbor, MI; Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI.Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI.Department of Urologic Sciences, University of British Columbia, Vancouver, British Columbia, Canada.Division of Endourology, Department of Urology, University of Michigan, Ann Arbor, MI.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

30195011

Citation

Aldoukhi, Ali H., et al. "Understanding the Popcorn Effect During Holmium Laser Lithotripsy for Dusting." Urology, vol. 122, 2018, pp. 52-57.
Aldoukhi AH, Roberts WW, Hall TL, et al. Understanding the Popcorn Effect During Holmium Laser Lithotripsy for Dusting. Urology. 2018;122:52-57.
Aldoukhi, A. H., Roberts, W. W., Hall, T. L., Teichman, J. M. H., & Ghani, K. R. (2018). Understanding the Popcorn Effect During Holmium Laser Lithotripsy for Dusting. Urology, 122, pp. 52-57. doi:10.1016/j.urology.2018.08.031.
Aldoukhi AH, et al. Understanding the Popcorn Effect During Holmium Laser Lithotripsy for Dusting. Urology. 2018;122:52-57. PubMed PMID: 30195011.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Understanding the Popcorn Effect During Holmium Laser Lithotripsy for Dusting. AU - Aldoukhi,Ali H, AU - Roberts,William W, AU - Hall,Timothy L, AU - Teichman,Joel M H, AU - Ghani,Khurshid R, Y1 - 2018/09/05/ PY - 2018/07/24/received PY - 2018/08/13/revised PY - 2018/08/22/accepted PY - 2018/9/9/pubmed PY - 2019/5/23/medline PY - 2018/9/9/entrez SP - 52 EP - 57 JF - Urology JO - Urology VL - 122 N2 - 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. SN - 1527-9995 UR - https://www.unboundmedicine.com/medline/citation/30195011/Understanding_the_Popcorn_Effect_During_Holmium_Laser_Lithotripsy_for_Dusting_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0090-4295(18)30919-1 DB - PRIME DP - Unbound Medicine ER -