Measurement and comparison of intrarenal pressures during retrograde intrarenal surgery using novel flexible ureteroscopes with integrated direct in-scope suction: An experimental ex vivo study.

Introduction: To evaluate the intrarenal pressure parameters of the 9.2 Fr (5.1 Fr working channel) and 7.5 Fr (3.6 Fr working channel) flexible ureteroscopes with direct-in-scope suction (DISS) in an ex vivo experimental setting. Material and methods: We performed an experimental study using an ex vivo porcine model using two DISS single-use digital videoureteroscopes: a 7.5 Fr PU3033AH and 9.2 Fr PU400A (Pusen, Zhuhai, China). Intrarenal pressures (IRPs) were measured with an automated irrigation pump set at 40, 60, 80, 100 mmHg, manual hand pumping and gravity fed-irrigation, with suction applied continuously and intermittently at 3-second intervals. Results: Higher IRPs were documented when the 9.2 Fr flexible ureteroscope was used compared to the 7.5 Fr scope, regardless of the irrigation setup. The highest IRP (45 mmHg) was documented with the 9.2 Fr scope, using manual pump irrigation and intermittent pumping with no suction. In contrast, the lowest IRP was reported with the 7.5 Fr scope and the automated pump at 40 mmHg. The pressure difference following 1second of suctioning was more pronounced with 9.2 Fr compared to 7.5 Fr. The 9.2 Fr ureteroscope with the 5.1 Fr working channel resulted in significantly shorter time to regain the initial IRP. Conclusions: For the first time in experimental studies we noted that irrigation through a wider 5.1 Fr working channel raises the baseline IRP faster than the classic 3.6 Fr working channel. Although these findings should be further investigated in a clinical setting, they should be taken into consideration to select the optimal strategy, to keep IRP at safe levels, and avoid complications.