We aimed to compare intrarenal pelvic pressure (IPP) levels between flexible ureteroscopy (fURS), mini-PCNL and standard PCNL in a kidney model.
A silicone model simulating the complete urinary tract was used for all the experiments. We compared fURS using a fURS with a 3.6-Fr working channel to mini-PCNL using a 12-Fr nephroscope with a 6.7-Fr working channel, and standard PCNL using a 26-Fr nephroscope. For the mini-PCNL, we used different sizes of operating sheaths: 15-Fr, 16.5-Fr and 21-Fr. For the standard PCNL, we used a 30-Fr operating sheath. We used an automated irrigation system to ensure a constant irrigation pressure. All the experiments were conducted at different instrument irrigation pressure levels: 40 cmH2O versus 193 cmH2O. We then compared the following parameters:
- fURS with and without ureteral access sheath, with empty working channel, and with 273 µm laser fiber;
- Mini-PCNL with different sheath sizes; nephroscope with empty working channel and with 365 µm laser fiber;
- Standard PCNL with 30-Fr access sheath, nephroscope with empty working channel, and with 11.4-Fr LithoClast Master lithotripter.
Retrograde insertion of a PressureWire (St-Jude Medical, 0.014” wire) placed into the renal pelvis allowed for continuous IPP monitoring. We recorded the value of IPP (cm H2O) when reaching a plateau. Measurements were repeated 5 times and mean values of IPP were reported.
The IPP was constantly higher for fURS compared to mini- and standard PCNL at 40 and 193 cmH2O.
· fURS: Presence of UAS or 273 µm laser fiber in the working channel decreased the IPP proportionaly to the different levels of irrigation pressure. The lowest IPP was reached with combination of UAS and laser fiber at 40 cmH2O.
· Mini-PCNL: IPP was inversely proportional to the operating sheath at all levels of irrigation pressure. Presence of 365 µm laser fiber into the working channel did not affect IPP at 40 cmH2O except for the 15/16-Fr sheath where it decreased. Presence of laser fiber decreased IPP at 193 cmH2O.
· Standard PCNL: IPP did not change at 40 cm H2O even with LithoClast. IPP increased substantially at 193 cmH2O with LithoClast.
This study found that IPP was higher in fURS in all circumstances compared to mini- and standard PCNL.