V6-12: The New Stone Age: Ureteroscopic stone “Dusting” with a 120-Watt holmium laser

Video

Introductions and Objectives
Techniques for laser lithotripsy during ureteroscopy (URS) have evolved with improvements in laser technology. The “Dusting” technique utilizes a high-power laser to ablate stones into fine powder. This was previously impractical due to limitations in energy settings using low-power systems. In this video we describe our experience of using a 120-Watt (W) holmium laser with dual dusting and fragmentation modes to perform flexible URS lithotripsy. We demonstrate the technique of ureteroscopic stone dusting for large renal and ureteral stones including use of ‘dancing’ and ‘chipping’ maneuvers.

Methods
We present two cases of renal stones (1.5 and 1.7 cm, respectively) and one of an impacted upper ureteral stone (1.7 cm) treated predominantly with dusting approach. Dusting is use of low pulse energy and high frequency (LoPE-HiFr) during laser lithotripsy. We used a 120-W holmium laser (Lumenis, San Jose, CA) with digital architecture that permits dual lithotripsy modes (dusting and fragmentation) and change in pulse width. A 200 micron ball-tip laser fiber was used (Flexiva, Boston Scientific, Boston, MA). Energy settings were adjusted according to stone composition, location and size, varying from 0.2-0.5 Joules (J) and rate between 30-80 Hertz (Hz).

Results
We demonstrate effective dusting technique to treat large stones in the kidney and ureter. Our dusting strategies include use of chipping, dancing and popcorning techniques. For chipping, the laser fiber is directed to the periphery of the stone to allow small fragments to chip off. For dancing, the tip of the laser fiber is brushed back and forth across the stone surface so that it is broken down layer by layer. During dusting of renal stones if they break into medium sized fragments, we push them into dependent calyces and utilize a “popcorning” technique (1J x 15Hz). In practice, dusting is also useful for impacted ureteral stones: dusted fragments are small and do not interfere with ureteroscopic vision while appropriate dusting settings avoid inadvertent retropulsion and stone migration. We used no retrieval devices for these cases.

Conclusions
High-power holmium lasers have opened a new frontier in ureteroscopic laser lithotripsy by permitting a dusting approach that ablates stones into powder. Further clinical evidence is needed to better understand the efficacy of dusting and determine if outcomes are similar to conventional laser lithotripsy strategies.

Funding: None