Comparison of the safety of flexible ureteroscopy with the different irrigation methods in a 3D print kidney model

Abstract

Objective To compare intrarenal pressure(IRP) and irrigation flow at various suspended water heights and use hand pumping during flexible ureteroscopy in an ex vivo 3D print kidney model. Methods A 3D print silica gel model was used to simulate the kidney. The ureteral access sheath(UAS) was connected to the kidney model and positioned at the ureteropelvic junction. Central venous pressure tubing was connected to monitor the pressure in the renal pelvis under different conditions. 12Fr and 14Fr sheath sizes were tested with different flexible ureteroscope(fURS) sizes of 7.5, 8.5, and 9.5Fr, respectively. The irrigation was gravity-based, and the hung water heights were set at 60, 90, 120, 150, and 180 cm. A manual pumping group was also measured. Results Using a 12Fr sheath with a 9.5Fr fURS loading with no accessories resulted in IRP ranging from 8.4–17.5 cmH2O while manual pumping perfusion pressure exceeded 60 cmH2O. Loading a 200um laser fiber decreased the pressure to 6.4–10.5 cmH2O and 4.0–5.0 cmH2O when loading a stone basket. Using a 14Fr sheath with a 9.5Fr fURS resulted in an IRP of 2.5-6.0 cmH2O, compared to 17cmH2O with manual pumping. With a 12Fr sheath and a 7.5Fr fURS, the IRP ranged from 5.4–8.2 cmH2O, while manual pumping resulted in 25.5 cmH2O. With a 14Fr sheath and a 7.5Fr fURS, the IRP ranged from 1.5-4.3cmH2O, while manual pumping resulted in 9.0 cmH2O. Conclusion When using a UAS in a flexible ureteroscopy, the IRP can be maintained in a safe range with different fURS/UAS combos with a suspended water height of less than 180cm. While in specific fURS/UAS(9.5Fr/12Fr) combos, the IRP exceeded the safe limit when using manual pumping. Gravity irrigation of less than 180cm hung water height is safe in this simulated clinical experiment environment.