Erbium:Yag laser lithotripsy mechanism

Kin Foong Chan, Ho Lee, Joel M.H. Teichman, Angela Kamerer, H. Stan McGuff, Gracie Vargas, Ashley J. Welch

Research output: Contribution to journalArticle

34 Scopus citations

Abstract

Purpose: We tested the hypothesis that the mechanism of long pulse erbium:YAG laser lithotripsy is photothermal. Materials and Methods: Human urinary calculi were placed in deionized water and irradiated with erbium:YAG laser energy delivered through a sapphire optical fiber. Erbium:YAG bubble dynamics were visualized with Schlieren flash photography and correlated to acoustic emissions measured by a polyvinylidene fluoride needle hydrophone. The sapphire fiber was placed either parallel or perpendicular to the calculus surface to assess the contribution of acoustic transients to fragmentation. Stones were irradiated using desiccated stone irradiated in air, hydrated stone irradiated in air and hydrated stone irradiated in water. Ablation crater sizes were compared. Uric acid stones were irradiated in water and the water was assayed for cyanide. Results: During the early phase of vapor bubble expansion, acoustic transients had minimal effects on calculus fragmentation. Fragmentation occurred due to direct absorption of laser energy transmitted to the calculus through the vapor channel between the sapphire fiber tip and calculus. The forward axial expansion of the bubble occurred more rapidly than the radial expansion. A parallel oriented fiber on the calculus surface produced no fragmentation but generated larger amplitude acoustic transients compared to perpendicular orientation. In perpendicular orientation the erbium:YAG laser did not generate any collapse acoustic waves but fragmentation occurred. Crater width was greatest for desiccated stones irradiated in air (p <0.03). Cyanide production increased as erbium:YAG irradiation of uric acid calculi increased, (r2 = 0.98). Conclusions: The erbium:YAG laser fragments stones through a photothermal mechanism.

Original languageEnglish (US)
Pages (from-to)436-441
Number of pages6
JournalJournal of Urology
Volume168
Issue number2
DOIs
StatePublished - Jan 1 2002
Externally publishedYes

Keywords

  • Kidney calculi
  • Lasers
  • Lithotripsy
  • Optics
  • Plasma

ASJC Scopus subject areas

  • Urology

Fingerprint Dive into the research topics of 'Erbium:Yag laser lithotripsy mechanism'. Together they form a unique fingerprint.

  • Cite this

    Chan, K. F., Lee, H., Teichman, J. M. H., Kamerer, A., McGuff, H. S., Vargas, G., & Welch, A. J. (2002). Erbium:Yag laser lithotripsy mechanism. Journal of Urology, 168(2), 436-441. https://doi.org/10.1016/S0022-5347(05)64653-8