Laser fibers and baskets. How do they affect suction and intrarenal pressures using the novel single-use flexible...

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.

An ex vivo experimental study was conducted using a freshly harvested porcine kidney. Measurements were performed under the following conditions: empty working channel, with a 200 µm laser fiber, a 272 µm laser fiber, and a 2.2 Fr nitinol basket. The evaluated parameters included: irrigation flow rates with gravity irrigation and an automated pump, maximum IRP without suctioning, time to collapse of the pelvicalyceal system, and time to regain baseline IRP after suctioning.

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.

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.