Risk of collateral damage to endourologic tools by holmium:YAG laser energy

Background and Purpose: Today, the holmium:YAG laser is the gold standard in endourologic stone treatment because of its high efficacy. However, guidewires and stone-extraction tools often are close to the fiber and may be damaged accidentally by the laser. The aim of our study was to evaluate the duration of laser application required to disrupt wires at different energy settings. Materials and Methods: Two standard wires (0.035-inch guidewire and 0.025-inch hydrophilic Terumo wire) and two baskets (1.9F Nitinol tipless and 3F stone extraction) were investigated. We used a holmium:YAG laser (Auriga; Wavelight Laser Technologie AG, Erlangen, Germany) and two fibers (230 and 365 mu m) at 800 and 2000 mJ and a 5-Hz pulse rate. The laser was brought into direct contact with the wires. Results: The average time required for transection was 55 to 103 seconds for a safety wire. The Terumo wire broke after 20 to 40 seconds of direct laser application; 15 to 34 seconds was required for a Dormia basket. Thin Nitinol basket wires were disrupted after only 1 to 4 seconds. One- and two-factorial variance analysis showed a high degree of significance (P < 0.0001) of the energy level and type of wire. Conclusion: The disruption of stone-extraction tools occurs in a remarkably short time with laser exposure, especially in case of Nitinol baskets, whereas guidewires are more resistant. Attention should be paid to avoiding contact of laser energy with wires and baskets during stone fragmentation.