Which is the best way to treat a stone on a flexible ureterorrenoscopy? | Opinion: Dusting

Flexible ureterorenolithotripsy is rapidly developing and becoming the treatment of choice around the World for the invasive treatment of lithiasis (1). According to calculi dimensions, they can be removed integrated or by using an intracorporeal lithotripter. According to laser parameters adjustments, it is possible to vaporize calculi (“dusting”). In this case, it is necessary to use high frequency of impulses (>15HZ), low energy (<0.5J) and long pulses (800 ɰsec), whenever the equipment allows for these options. Recently, it has been debated which is the best way to program the equipment at the moment of calculi lithotripsy. There are few evidences in literature to conclude, but it seems that dusting has some advantages in relation to fragmentation + basketing. An experimental work performed in 1999 showed that the use of high energy during lithotripsy increased the quantity of larger fragments; the authors suggested the use of <1 J energy and high frequency of impulses, that characterizes dusting (2). Another more recent experimental study also verified that, by using several potencies and frequencies, that the produced fragments were lower than 1 mm in almost all groups that used 0.2J of energy. Those fragments increased proportionally to the increase of Joules of Holmium laser (3). At present, endourologic post-surgical residual calculi have become a future concern, since they can cause pain, urinary tract obstruction and need of reintervention. The EDGE group collected data from 6 centers and verified that among 232 patients with residual lithiasis, 44% evolved with some colic event and 29% needed surgical reintervention. Fragments bigger than 4 mm were the most probable to grow (p<0.001) and associated with bigger complications (p=0.039) (4). Also, when bigger fragments are produced, the need for basket removal generates more movement of the appliance through the sheath, increasing the risk of displacement and ureteral lesions. It is possible to treat efficiently calculi generating power or very tiny fragments that don’t need to be removed, dismissing the need of a basket and lowering costs (3). Morhardt, using a 120 W Holmium Laser and dusting, showed efficient resolution of renal and ureteral bigger calculi (1.5–1.7cm) (5). A prospective multicenter study (EDGE group) compared dusting method to fragmentation and basketing in the treatment of intra-renal calculi with 5 to 20mm. 59 patients were studied. Calculi were bigger in the dusting group and stone-free rate was lower (60.9%). But only 17% of residual fragments DIFFERENCE OF OPINION