Initial clinical experience with the pulsed solid-state thulium YAG laser from Dornier during RIRS: first 25 cases

Introduction Holmium: yttrium-aluminium-garnet (Ho:YAG) and thulium fiber (TFL) lasers are currently the two laser sources recommended for endocorporeal laser lithotripsy (ELL). Recently, the pulsed-thulium:YAG (Tm:YAG) laser was also proposed for ELL, as an answer to both Ho:YAG and TFL limitations. We aimed to evaluate the efficiency, safety, and laser settings of Tm:YAG laser in ELL during retrograde intrarenal surgery (RIRS). Methods A prospective study of the first 25 patients with ureteral and renal stones who underwent RIRS using the Thulio (pulsed-Tm:YAG, Dornier (c), Germany) was performed in a single center. 272 mu m laser fibers were used. Stone size, stone density, laser-on time (LOT) and laser settings were recorded. We also assessed the ablation speed (mm(3)/s), Joules/mm(3) and laser power (W) values for each procedure. Postoperative results, such as stone-free rate (SFR) and zero fragments rate (ZFR) were also recorded. Results A total of 25 patients were analyzed (Table 1). The median (IQR) age was 55 (44-72) years old. Median (IQR) stone volume was 2849 (916-9153)mm(3). Median (IQR) stone density was 1000 (600-1174)HU. Median (IQR) pulse energy, pulse rate and total power were 0.6 ( 0.6-0,8)J, 15(15-20)Hz and 12( 9-16)W, respectively. All procedures used "Captive Fragmenting" pulse modulation (Table 2). The median ( IQR) J/mm(3) was 14,8 (6-21). The median (IQR) ablation rate was 0,75 (0,46-2)mm(3)/s. One postoperative complications occurred (streinstrasse). SFR and ZFR were 95% and 55%, respectively. Conclusion The pulsed-Tm:YAG laser is a safe and effective laser source for lithotripsy during RIRS, using low pulse energy and low pulse frequency.