Impact of difference in height of automated irrigation system and height of kidney on intrarenal pressure in an in vitro kidney model

Purpose: To clarify the impact of the difference in height between an automated irrigation system and the renal pelvis using an artificial kidney model. Methods: A flexible ureteroscope was placed into an artificial kidney model centrally through the ureteral access sheath, and the pressure in the model was measured as the intrarenal pressure (IRP). Three types of irrigation systems were used in this study: a pressure-controlled system, a gravity-based irrigation system, and an infusion pump. During measurements, either the working channel of the flexible ureteroscope was unoccupied or various instruments (200-μm laser fiber and 1.5-Fr retrieval basket) were inserted into the working channel. The three irrigation systems were evaluated under three conditions: at the same height as the artificial kidney model, 50 cm higher than the model, and 50 cm lower than the model. The maximum IRP was measured and compared. Results: The IRP was affected by the height difference between the pressure-controlled system and the artificial kidney model in all conditions (p < 0.05). Additionally, the IRP was affected by the height difference between the gravity-based irrigation system and the artificial kidney model in all conditions (50 cm taller vs. same height, p < 0.05; 50 cm taller vs. 50 cm lower, p < 0.05). However, the IRP was not affected by the height difference between the infusion pump and the artificial kidney model in all conditions. Conclusion: Clinicians should check whether there is a difference between the height of the kidney and the height of the pressure-controlled system.