Kidney stone ablation times and peak saline temperatures during Holmium: YAG and Thulium fiber laser lithotripsy, in vitro, in a ureteral model

Luke A. Hardy, Christopher R. Wilson, Pierce B. Irby, Nathaniel M. Fried

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Scopus citations


Using a validated in vitro ureter model for laser lithotripsy, the performance of an experimental Thulium fiber laser (TFL) was studied and compared to clinical gold standard Holmium:YAG laser. The Holmium laser (λ = 2120 nm) was operated with standard parameters of 600 mJ, 350 μs, 6 Hz, and 270-μm-core optical fiber. TFL (λ = 1908 nm) was operated with 35 mJ, 500 μs, 150-500 Hz, and 100-μm-core fiber. Urinary stones (60% calcium oxalate monohydrate / 40% calcium phosphate), of uniform mass and diameter (4-5 mm) were laser ablated with fibers through a flexible video-ureteroscope under saline irrigation with flow rates of 22.7 ml/min and 13.7 ml/min for the TFL and Holmium laser, respectively. The temperature 3 mm from tube's center and 1 mm above mesh sieve was measured by a thermocouple and recorded during experiments. Total laser and operation times were recorded once all stone fragments passed through a 1.5-mm sieve. Holmium laser time measured 167 ± 41 s (n = 12). TFL times measured 111 ± 49 s, 39 ± 11 s, and 23 ± 4 s, for pulse rates of 150, 300, and 500 Hz (n = 12 each). Mean peak saline irrigation temperatures reached 24 ± 1 °C for Holmium, and 33 ± 3 °C, 33 ± 7 °C, and 39 ± 6 °C, for TFL at pulse rates of 150, 300, and 500 Hz. To avoid thermal buildup and provide a sufficient safety margin, TFL lithotripsy should be performed with pulse rates below 500 Hz and/or increased saline irrigation rates. The TFL rapidly fragmented kidney stones due in part to its high pulse rate, high power density, high average power, and reduced stone retropulsion, and may provide a clinical alternative to the conventional Holmium laser for lithotripsy.

Original languageEnglish (US)
Title of host publicationPhotonic Therapeutics and Diagnostics XI
ISBN (Print)9781628413939
StatePublished - 2015
Externally publishedYes
EventPhotonic Therapeutics and Diagnostics XI - San Francisco, United States
Duration: Feb 7 2015Feb 8 2015


OtherPhotonic Therapeutics and Diagnostics XI
Country/TerritoryUnited States
CitySan Francisco


  • Ablation
  • Fragmentation
  • Holmium
  • Lithotripsy
  • Temperatures
  • Thulium
  • Vaporization

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Radiology Nuclear Medicine and imaging


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