Holmium laser for RIRS. Watts are we doing?

Objective: To review recent and relevant information regarding the use of high-power (HPL) and low-power (LPL) Holmium:YAG lasers (Ho:YAG) in retrograde intrarenal surgery (RIRS) for lithotripsy. METHODS: A PubMed/Embase search was conducted and recent and relevant papers on Ho:YAG for RIRS were reviewed.

Results: Settings for Ho:YAG are pulse energy (PE), pulse frequency (PF), and pulse width. Currently, the majority of LPL can also adjust pulse-width but cannot reach PF as high as HPL, however, the higher energy outputs reached by HPL are rarely useful in lithotripsy. Higher PE might enhance ablation but generates larger fragments and higher retropulsion. Pulse width does not affect energy output but delivers energy for a longer time-length. Dusting and basketing are complementary techniques. Dusting seeks to pulverize stones into particles ≤250 μm avoiding the use of instruments for stone retrieval, whereas in fragmenting, the stones are break into smaller pieces which are then retrieved. Dusting can prevent the use of supplies such as access sheaths and baskets and also prevent the complications related to their use. However, is not always feasible in clinical practice to fully ablate a stone into dust, then the use of this supplies and popcorn technique are helpful for rendering a patient stonefree. The energy gap between HPL and LPL is wide and leaves room for a mid-power laser classification, which can overcome the main drawback of LPL, the expenses of HPL, and still holding its versatility for other procedures beyond stones.

Conclusions: HPL and LPL have similar effectiveness, but long-term cost-effectiveness comparisons are underexplored. Newer HPL would need to be compared to emerging technologies as the thulium fiber, and prove superiority to mid-power laser to determine how powerful is enough for Ho:YAG in the years to come.