Abu Dhabi, United Arab Emirates (UroToday.com) This session overviewed new techniques in stone disease, including dusting, fragmenting, popcorning, and popdusting. Traditionally, a holmium laser is used for these procedures. The structure of the holmium laser used for urolithiasis is a laser cavity with two mirrors and one opening, a crystal with holmium ions, and a laser that pumps through the crystal, excited holmium ions through the laser cavity. This is the holmium:YAG (yttrium-aluminum-garnet) laser, and the gold standard for lithotripsy.

The energy, frequency, and pulse duration of this laser can be fixed. Energy can be set at low (0.5 J) or high (15-80 Hz), energy can be set at low (1 – 5 Hz), or high (15-80 Hz), and the pulse duration is also customizable. This creates at least 8 different combinations of settings, which can be chosen to utilize the specific technique desired. Dr. Doizi recommends altering first the pulse duration, then energy, and finally frequency.

The settings for dusting include a long pulse (800 microseconds), low energy (0.5 J) and high frequency (15-20 Hz), with an estimated power of 7.5-10 W. Fragmentation entails short pulse (200 microseconds), high energy (1.5-2 J), low frequency (5 Hz), with the same power as dusting (7.5-10 W). Popcorning settings are aa long pulse (600 microseconds), high energy (1-1.5 J), and high frequency (10-15 Hz), with a higher power (10-17.5 W).

Popcorning is a mixture of dusting and fragmentation. Dusting creates much smaller fragments while fragmentation creates larger fragments. A mixture of these techniques is required to reduce stone burden. The recommended dusting technique is to avoid touching the surface of the papilla or ureter, but to be “moving all the time.” This creates dust, which is defined as < 250 microns. Popcorning is a mix of dusting and fragmentation. Popcorning is high energy for big fragments, while popdusting is low energy and high frequency with long duration to create very small particulates. Fragmentation and basketing would require using the basket approximately 64 times. The mixture of the techniques means fewer passes with a basket and a higher stone free rate.

The talk was concluded with a discussion of the thulium fiber laser. This is a smaller fiber laser that produces smaller particulates with lower energy. In preliminary experimental uses, it produced twice as much stone dust as the holmium laser.

Presented by: Steeve Doizi, MD, MSC, Chef de Clinique Assistant, Service d’Urologie, Hôpital Tenon, APHP

Written by Rajiv Karani, Associate Research Fellow, Department of Urology, University of California, Irvine, at the 37th World Congress of Endourology (WCE) – October 29th-November 2nd, Abu Dhabi, United Arab Emirates