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EAU 2018: Assessing Irrigation Flows Influence on Clearance of Renal Calculi Fragments During PCNL: A Hydrodynamic Computerized and Practical Model Study

Copenhagen, Denmark (UroToday.com) Dr. Dekalo, clinical urologist from the Tel-Aviv Sourasky Medical Center in Tel-Aviv, Israel, presented a continuative study on a previous finding regarding the usefulness of irrigation flows within a kidney model. Recent findings suggest that that irrigation flow contributes to the improvement of endoscopic vision while also flushing out of stone fragments created during percutaneous nephrolithotomy (PCNL). The study that came to this realization used a kidney model of a single calyx to determine the effectiveness of irrigation. Dr. Dekalo expressed his concerns with this study since it did not accurately represent the intrarenal collecting system of a human kidney. For this reason, Dr. Dekalo and his team aimed to further analyze the processes of irrigation and the potential benefits they hold in a computerized model (CM) and PCNL practice model (PM). 

For the CM, software from COMSOL Multiphysics® was used to simulate the irrigation flows and particles through a two dimensional model of a kidney. This kidney model was depicted by graphically translating computerized tomography (CT) images into a computer. In addition, a transparent PCNL training model with solid particles was constructed based on the same CT images. A 24 French nephroscope and 30 French nephrostomy sheath was used to simulate a PCNL while movements of particles and irrigation flow were monitored. Various flow velocities and PCNL positions were analyzed as well. 

Dr. Dekalo chose to mainly present his findings of particle clearance at 90° at various speeds and 1 m/s at various angles. It was determined by the CM predictive model that a high velocity of 1 m/s at 90° would result in a significantly higher particle clearance than 0.25 m/s. Additionally, perpendicular positioning of the instrument at 90° produced a significantly higher clearance rate than 45°. These predictions were validated in the practical model using a nephroscope. 

In conclusion, Dr. Dekalo and his team confirmed that clearance of stone particles is produced via irrigation, but only when irrigative flow perpendicularly directed towards the calyx of choice. The effectiveness of flow was also determined to be enhanced by greater velocities as well. In calyces without direct irrigation, there is no effective flow or particle clearance. An important secondary endpoint was discovered, namely being the confirmed efficacy of computerized models for predicting and calculating hydrodynamic flow through a renal model. 


Presented by: S. Dekalo, Tel-Aviv Sourasky Medical Center, Dept. of Urology, Tel-Aviv, Israel

Co-Authors: Barghouty Y. 1 , Shlain S. 2 , Liberzon A. 3 , Paster A. 3 , Aviram G. 4 , Sofer M. 1

Author Information:
1. Tel-Aviv Sourasky Medical Center, Dept. of Urology, Tel-Aviv, Israel 
2. School of Mechanical Engineering, Dept. of Hydrology, Tel-Aviv, Israel
3. Tel-Aviv University , Dept. of Hydrology, Tel-Aviv, Israel
4. Tel-Aviv Sourasky Medical Center, Dept. of Radiology, Tel-Aviv, Israel

Written by: Zachary Valley MD, Department of Urology, University of California-Irvine at the 2018 European Association of Urology Meeting EAU18, 16-20 March, 2018 Copenhagen, Denmark