Laser fibers and baskets. How do they affect suction and intrarenal pressures using the novel single-use flexible direct in-scope suction ureteroscopes?

Introduction: To evaluate intrarenal pressures (IRP) and suction performance of two novel flexible ureteroscopes equipped with a direct-in-scope suction (DISS) feature - the 7.5 Fr PU3033AH and the 9.2 Fr PU400A - both with an empty working channel and with various working instruments inserted. Material and methods: An Results: The highest IRP of 34 mmHg was recorded with the 9.2 Fr scope under 100 mmHg irrigation pressure. Irrespective of the irrigation system used, the introduction of working instruments significantly reduced the IRP for both 7.5 Fr and 9.2 Fr DISS scopes. A longer time was required to collapse the pelvicalyceal system and regain the basal intrarenal pressure when working instruments were used. The thicker the diameter of the instrument, the greater the impact on flowrate, IRP, collapse of the system, and regain of the pressure was observed. The latter trends were less pronounced with the 9.2 Fr scope with a wider 5.1 Fr working channel. Conclusions: The 9.2 Fr DISS ureteroscope demonstrated higher irrigation flow rates and IRP, and shorter times to system collapse and recovery compared to the 7.5 Fr scope. However, the insertion of working instruments negatively affected all measured parameters, with a greater impact observed in the 7.5 Fr scope due to its narrower channel.