Evaluation of a novel circulation system for ureteroscopic laser lithotripsy in vitro

To evaluate the cooling effect and other advantages of a novel circulation system for ureteroscopic holmium laser lithotripsy (URSL) in a standardized in vitro model.

The novel circulation system was assembled by connecting a 4Fr ureteral catheter and a filter. Trails were divided into a new URSL group and a conventional URSL group. First, different power settings (18-30 W) of the holmium laser and irrigation flow rates (20-50 mL/min) were used to evaluate the thermal effect on the lithotripsy site of all groups. Then, renal pelvic temperature and pressure were assessed during URSL at a power of 1.5 J/20 Hz and irrigation flow rates of (20-50 mL/min). Finally, the whole process of lithotripsy was performed at 1.5 J/20 Hz (operator duty cycle ODC: 50%) with an irrigation flow rate of 30 mL/min. The time required for lithotripsy, visual field clarity, and stone migration were observed.

Temperature of the lithotripsy point was significantly lower in the new URSL group than in the conventional group (P < 0.05) with irrigation rates (20, 30 mL/min). The renal pelvic pressure of the new group was significantly lower than that of the conventional group in which intrarenal hypertension developed at an irrigation rate of 50 ml/min. The new group had better visual clarity and lesser stone upward migration when lithotripsy was performed at 1.5 J/20 Hz and 30 ml/min.

The novel circulation system is more effective in reducing the thermal effects of URSL, pelvic pressure, stone upward migration, and improving the visual clarity of the operative field.