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Urolithiasis

, Volume 47, Issue 4, pp 377–382 | Cite as

An in vitro evaluation of laser settings and location in the efficiency of the popcorn effect

  • Daniel A. WollinEmail author
  • Westin R. Tom
  • Ruiyang Jiang
  • W. Neal Simmons
  • Glenn M. Preminger
  • Michael E. Lipkin
Original Paper

Abstract

To examine different locations and laser settings’ effects on the efficiency of the “popcorn” method of laser lithotripsy, which consists of placing the laser in a group of small stones and firing continuously to break them into smaller particles. Pre-fragmented BegoStones were created between 2 and 4 mm to mimic typical popcorning conditions. A 0.5 g collection of fragments was placed into 3D-printed models (a spherical calyx and ellipsoid pelvis model) and a 200-µm laser fiber was positioned above the stones. The laser was fired for 2 min with irrigation, with 5 trials at each setting: 0.2 J/50 Hz, 0.5 J/20 Hz, 0.5 J/40 Hz, 1 J/20 Hz, 0.2 J/80 Hz, 0.5 J/80 Hz. After drying, fragmentation efficiency was determined by calculating the mass of stones reduced to sub-2 mm particles. Statistical analysis was performed with ANOVA and Student’s t test. The trials within the calyx model were significantly more efficient compared to the pelvis (0.19 vs 0.15 g, p = 0.01). When comparing laser settings, there was a difference between groups by one-way ANOVA [F(5,54) = 8.503, p = 5.47 × 10−6]. Post hoc tests showed a power setting of 0.5 J/80 Hz was significantly more efficient than low-power settings 0.2 J/50 Hz and 0.5 J/20 Hz (p < 0.05). Additionally, 0.2 J/50 Hz was significantly less efficient than 0.5 J/40 Hz, 1 J/20 Hz, and 0.2 J/80 Hz. Popcorning is most efficient in smaller spaces; we recommend displacement of stones into a calyx before popcorning. No difference was seen between high-power settings, although 0.5 J/40 Hz and 0.5 J/80 Hz performed best, suggesting that moderate energy popcorning methods with at least 0.5 J per pulse are most efficient.

Keywords

Holmium Laser Ureteroscopy Urolithiasis Popcorn 

Notes

Funding

No external funding was received for this study.

Compliance with ethical standards

Conflict of interest

Dr. Preminger serves as a consultant for Boston Scientific and Retrophin. Dr. Lipkin serves as a consultant for Boston Scientific.

Ethical approval

This article does not contain any studies with human participants performed by any of the authors.

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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Division of Urologic SurgeryDuke University Medical CenterDurhamUSA
  2. 2.Duke University School of MedicineDurhamUSA
  3. 3.Department of Mechanical Engineering and Materials ScienceDuke UniversityDurhamUSA

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