Experimental utilization of the holmium laser in a model of ureteroscopic lithotripsy: Energy analysis

Background and Objective: Medical lasers have rapidly expanded in both indi cations and utilization. We have developed a simple model for the investiga tion of various modalities of lithotripsy using readily available silicate stones of uniform mass. Materials and Methods: The holmium:YAG VersaPulse Select (Coherent, Pale Al to, CA) was used in these experiments to define the relation between fiber diameter and efficacy of stone fragmentation. For each fiber, lithotripsy w as performed in an incremental fashion at 0.6, 0.8, and 1.0 J at a frequenc y of 10, 16, and 20 pulses per second at each energy level. Results: Total kilojoules did not differ between any fibers investigated, s upporting the consistency of our methodology. The power density of the holm ium laser energy, as expressed as total kJ/area, decreases in proportion to increasing fiber diameter. We expected an increase in fragmentation succes s as fiber diameter decreased (at equal energy output). However, peak litho tripsy occurred with the 365- and 550-mu m fibers, whereas neither the 200- nor the 1000-mu m fibers was effective. Conclusion: This model utilizing a silicate stone phantom supports our clin ical observation that the 365-mu m fiber land additionally the 550-mu m fib er) provides the best method for efficient intracorporeal lithotripsy.