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.
Holmium Laser Ureteroscopy Urolithiasis Popcorn
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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.
This article does not contain any studies with human participants performed by any of the authors.
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