title: High-Frequency Dusting Versus Conventional Holmium Laser Lithotripsy for Intrarenal and Ureteral Calculi.
abstract: The efficiency of holmium laser lithotripsy for urolithiasis depends upon several factors, including laser pulse energy and frequency and stone composition and retropulsion. This study investigates the complex interplay between these factors and quantifies lithotripsy efficiency using different laser settings in a benchtop kidney and ureter model.
  
  
  
  In vitro caliceal and ex vivo porcine ureteral models were constructed. Calcium oxalate monohydrate stones were fragmented using a 200-μm laser fiber. In the caliceal model, stone fragmentation and vaporization rates at settings of 0.6 J/5 Hz, 0.2 J/15 Hz, and 0.2 J/50 Hz were compared. In the ureteral model, fragmentation time, retropulsion rate, fragmentation rate, and fragmented stone weight were compared at settings of 0.6 J/5 Hz and 0.2 J/15 Hz. Retropulsive forces generated at 0.6 J/5 Hz, 0.2 J/15 Hz, and 0.2 J/50 Hz settings were compared. Analysis was performed using Student's t-test and one-way ANOVA.
  
  
  
  In the caliceal model, the 0.6 J/5 Hz setting fragmented and vaporized stones at a higher rate than the 0.2 J/15 Hz setting (0.072 vs. 0.049 mg/s; p < 0.001). However, when the 0.2 J energy setting was combined with the 50 Hz frequency, the fragmentation rate (0.069 mg/s) was similar to the fragmentation rate at 0.6 J/5 Hz (0.072 mg/s; p = 0.677). In the ureteral model, the 0.6 J/5 Hz setting produced higher fragmentation rates (0.089 vs. 0.049 mg/s; p < 0.001), but resulted in significantly lower fragmented stone weight overall (16.815 vs. 25.485 mg; p = 0.009) due to higher retropulsion rates (0.732 vs. 0.213 mm/s; p < 0.001). Retropulsive forces decreased significantly when pulse energy decreased from 0.6 to 0.2 J (0.907 vs. 0.223 N; p < 0.001). Frequency did not affect retropulsive force at 15 and 50 Hz settings (0.223 vs. 0.288 N; p = 0.509).
  
  
  
  Laser lithotripsy of calcium oxalate monohydrate stones in the ureter should be performed using the low-energy, moderate-frequency dusting setting to minimize retropulsion and maximize efficiency. In the renal calix, the low-energy high-frequency setting performed similarly to the high-energy low-frequency setting.
authors.affiliation: Department of Urology, Loma Linda University Health , Loma Linda, California.
authors.forename: Roger
authors.initials: R
authors.lastname: Li
authors.affiliation: Department of Urology, Loma Linda University Health , Loma Linda, California.
authors.forename: David
authors.initials: D
authors.lastname: Ruckle
authors.affiliation: Department of Urology, Loma Linda University Health , Loma Linda, California.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Keheila
authors.affiliation: Department of Urology, Loma Linda University Health , Loma Linda, California.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Maldonado
authors.affiliation: Department of Urology, Loma Linda University Health , Loma Linda, California.
authors.forename: Michelle
authors.initials: M
authors.lastname: Lightfoot
authors.affiliation: Department of Urology, Loma Linda University Health , Loma Linda, California.
authors.forename: Muhannad
authors.initials: M
authors.lastname: Alsyouf
authors.affiliation: Department of Urology, Loma Linda University Health , Loma Linda, California.
authors.forename: Alexander
authors.initials: A
authors.lastname: Yeo
authors.affiliation: Department of Urology, Loma Linda University Health , Loma Linda, California.
authors.forename: Samuel R
authors.initials: SR
authors.lastname: Abourbih
authors.affiliation: Department of Urology, Loma Linda University Health , Loma Linda, California.
authors.forename: Gaudencio
authors.initials: G
authors.lastname: Olgin
authors.affiliation: Department of Urology, Loma Linda University Health , Loma Linda, California.
authors.forename: Javier L
authors.initials: JL
authors.lastname: Arenas
authors.affiliation: Department of Urology, Loma Linda University Health , Loma Linda, California.
authors.forename: D Duane
authors.initials: DD
authors.lastname: Baldwin
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D004195:Disease Models, Animal; D007669:Kidney Calculi / Q000628:therapy*; D053844:Lasers, Solid-State / Q000627:therapeutic use*; D017602:Lithotripsy, Laser / Q000379:methods*; D013552:Swine; D014514:Ureteral Calculi / Q000628:therapy*
keywords: laser; metabolic stone; ureteral stones; ureteroscopy; urolithiasis