The hydrodynamic basis of the vacuum cleaner effect in continuous-flow PCNL instruments: an empiric approach and mathematical model

Purpose Passive removal of stone fragments in the irrigation stream is one of the characteristics in continuous-flow PCNL instruments. So far the physical principle of this so-called vacuum cleaner effect has not been fully understood yet. The aim of the study was to empirically prove the existence...

Full description

Saved in:
Bibliographic Details
Published in:World journal of urology 2016-05, Vol.34 (5), p.717-724
Main Authors: Mager, R., Balzereit, C., Gust, K., Hüsch, T., Herrmann, T., Nagele, U., Haferkamp, A., Schilling, D.
Format: Article
Language:English
Subjects:
Equipment Design
Hydrodynamics
Medicine
Medicine & Public Health
Models, Theoretical
Nephrology
Nephrostomy, Percutaneous - instrumentation
Nephrostomy, Percutaneous - methods
Oncology
Original Article
Urology
Vacuum
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Purpose Passive removal of stone fragments in the irrigation stream is one of the characteristics in continuous-flow PCNL instruments. So far the physical principle of this so-called vacuum cleaner effect has not been fully understood yet. The aim of the study was to empirically prove the existence of the vacuum cleaner effect and to develop a physical hypothesis and generate a mathematical model for this phenomenon. Methods In an empiric approach, common low-pressure PCNL instruments and conventional PCNL sheaths were tested using an in vitro model. Flow characteristics were visualized by coloring of irrigation fluid. Influence of irrigation pressure, sheath diameter, sheath design, nephroscope design and position of the nephroscope was assessed. Experiments were digitally recorded for further slow-motion analysis to deduce a physical model. Results In each tested nephroscope design, we could observe the vacuum cleaner effect. Increase in irrigation pressure and reduction in cross section of sheath sustained the effect. Slow-motion analysis of colored flow revealed a synergism of two effects causing suction and transportation of the stone. For the first time, our model showed a flow reversal in the sheath as an integral part of the origin of the stone transportation during vacuum cleaner effect. The application of Bernoulli’s equation provided the explanation of these effects and confirmed our experimental results. Conclusions We widen the understanding of PCNL with a conclusive physical model, which explains fluid mechanics of the vacuum cleaner effect.
ISSN:0724-4983
1433-8726
DOI:10.1007/s00345-015-1682-5