The following is a summary of “Vortex Effect in Minimally Invasive Percutaneous Nephrolithotomy,” published in the October 2023 issue of Urology by Ito, et al.
For a study, researchers sought to elucidate the physical principles underlying the vortex effect, enhancing our comprehension of its applicability in minimally invasive percutaneous nephrolithotomy (MIP) procedures.
Acrylic phantom models were constructed to mimic the cross-sectional area (CSA) ratio of a MIP nephroscope and access sheaths (15/16F and 21/22F MIP-M, Karl Storz). The nephroscope phantom had a 10 mm diameter, while the access sheaths were 14 mm (CSA ratio: 0.69) and 20 mm (CSA ratio: 0.30) in diameter. Hydrolysis was induced in the models, and hydrogen bubbles were introduced to enhance flow visualization using a green laser background. After calibration, the experimental flow rate was set at 12.0 mL/s. Three 30-second trials evaluating the flow were conducted for each model. Computational fluid dynamic simulations were employed to determine speed and pressure profiles.
In both models, as fluid from the nephroscope phantom sought to move toward the collecting system, a stagnation point was observed, with no fluid entering the collecting system phantom. With the 14 mm sheath, multiple vortices were randomly generated, accompanied by a pressure gradient (PG) of 114.4 N/m2 between the nephroscope’s tip and the stagnation point. Conversely, the 20 mm sheath exhibited a significantly smaller PG (19.4 N/m2), with no noticeable vortices.
Fluid speed and equipment geometry intricately regulated the PG and vortex field, contributing to the vortex effect. At a consistent flow rate, a higher CSA ratio between the nephroscope and access sheath enhanced the vortex effect’s efficacy in MIP procedures.
Source: goldjournal.net/article/S0090-4295(23)00580-0/fulltext
