Comparison of Superpulse Thulium Fiber Laser vs. Holmium Laser for Ablation of Renal Calculi in an In-Vivo Porcine Model.

INTRODUCTION AND OBJECTIVES We sought to compare the effectiveness and efficiency of the superpulse thulium fiber laser (sTFL to the holmium laser (Ho:YAG) for ureteroscopic "dusting" of implanted renal stones in an in-vivo porcine model. METHODS Twenty-four porcine kidneys (12 juvenile female Yorkshire pigs) were randomized to Ho:YAG or sTFL treatment groups. Canine calcium oxalate stones were scanned with computed tomography to calculate stone volume and stone density; the stones were randomized and implanted into each renal pelvis via an open pyelotomy. In all trials, a 14Fr, 35 cm ureteral access sheath was placed. With a 9.9F dual lumen flexible ureteroscope, laser lithotripsy was performed using dusting settings: Ho:YAG 200µm laser fiber at 16W (0.4J, 40Hz) or sTFL 200µm laser fiber at 16W (0.2J, 80Hz). Lithotripsy was continued until no fragments over 1mm were observed. No stone basketing was performed. Throughout the procedures, intra-renal and renal pelvis temperatures were measured using two percutaneously positioned K-type thermocouples, one in the upper pole calyx and one in the renal pelvis. After the lithotripsy, the ureteropelvic junction was occluded, the kidneys were bi-valved and all residual fragments were collected, dried, weighed, and then measured with an optical laser particle sizer. RESULTS Implanted stones were similar in volume and density in both groups. Intraoperative collecting system temperatures were similar for both groups (all <44ºC). Compared to Ho:YAG, sTFL ablated stones faster (9min vs. 27min, p<0.001) with less energy expenditure (8kJ vs. 26kJ, p<0.001), and a greater stone clearance rate (73% vs. 45%, p=0.001). After sTFL lithotripsy, 77% of the remaining fragments were ≤1 mm versus 17% of fragments ≤1 mm after Ho:YAG treatment (p<0.001). CONCLUSIONS In an in-vivo porcine kidney, using dusting settings, sTFL lithotripsy resulted in shorter ablation times, higher stone clearance rates, and markedly smaller stone fragments than Ho:YAG lithotripsy.