title: Introducing a Novel In Vitro Model to Characterize Hydrodynamic Effects of Percutaneous Nephrolithotomy Systems.
abstract: OBJECTIVE
  To widen the understanding of the fluid mechanics during percutaneous nephrolithotomy (PCNL), a new in vitro model for empiric studies was developed. Our first aim was to characterize common PCNL systems with regard to their intrapyelocaliceal pressure and their irrigation flow volume as possible parameters of hydrodynamic invasiveness.
  
  
  METHODS
  The model is based on a watertight cylindrical cast. Low pressure miniaturized PCNL (miniPCNL) systems and conventional PCNL systems were tested. Intrapelvic pressure and the total of irrigation flow volume per minute were measured for each PCNL system at 10 predefined levels of irrigation pressure between 40 and 130 cm H2O.
  
  
  RESULTS
  Linear regression showed a linear relation between irrigation pressure and intrapelvic pressure. Compared with miniPCNL systems, conventional PCNL sheaths with closed Rutner sidearm generate significantly higher intrapelvic pressures. Opening the Rutner sidearm leads to a decrease in intrapelvic pressure to the level of the open mini PCNL systems. Polynomal regression revealed a square root relation between irrigation pressure and irrigation flow volume.
  
  
  CONCLUSIONS
  Our in vitro model is suitable for obtaining reliable and valid data of intrapelvic pressure and irrigation flow volume of commonly used PCNL systems. Conventional PCNL sheaths with opened Rutner sidearm provide intrapelvic pressure and irrigation volume similar to miniPCNL. Consequently, a relevant difference of the hydrodynamic impact between conventional and miniPCNL systems are not necessarily to be assumed. Regression analysis revealed a new starting point for further empiric research of fluid mechanics during PCNL.
authors.affiliation: 1 Department of Urology and Paediatric Urology, University Hospital Frankfurt , Frankfurt, Germany .
authors.forename: Rene
authors.initials: R
authors.lastname: Mager
authors.affiliation: 2 ExperTeach GmbH , Dietzenbach, Germany .
authors.forename: Christopher
authors.initials: C
authors.lastname: Balzereit
authors.affiliation: 1 Department of Urology and Paediatric Urology, University Hospital Frankfurt , Frankfurt, Germany .
authors.forename: Michael
authors.initials: M
authors.lastname: Reiter
authors.affiliation: 1 Department of Urology and Paediatric Urology, University Hospital Frankfurt , Frankfurt, Germany .
authors.forename: Kilian
authors.initials: K
authors.lastname: Gust
authors.affiliation: 1 Department of Urology and Paediatric Urology, University Hospital Frankfurt , Frankfurt, Germany .
authors.forename: Hendrik
authors.initials: H
authors.lastname: Borgmann
authors.affiliation: 1 Department of Urology and Paediatric Urology, University Hospital Frankfurt , Frankfurt, Germany .
authors.forename: Tanja
authors.initials: T
authors.lastname: Hüsch
authors.affiliation: 3 Department of Urology and Andrology, Tyrol District Hospital Hall , Tirol, Austria .
authors.forename: Udo
authors.initials: U
authors.lastname: Nagele
authors.affiliation: 1 Department of Urology and Paediatric Urology, University Hospital Frankfurt , Frankfurt, Germany .
authors.forename: Axel
authors.initials: A
authors.lastname: Haferkamp
authors.affiliation: 1 Department of Urology and Paediatric Urology, University Hospital Frankfurt , Frankfurt, Germany .
authors.forename: David
authors.initials: D
authors.lastname: Schilling
mesh_terms: D006801:Humans; D057446:Hydrodynamics; D066298:In Vitro Techniques; D007669:Kidney Calculi / Q000601:surgery*; D008962:Models, Theoretical; D009403:Nephrostomy, Percutaneous / Q000295:instrumentation / Q000379:methods*; D010388:Pelvis / Q000502:physiology; D011312:Pressure; D012044:Regression Analysis; D007507:Therapeutic Irrigation / Q000295:instrumentation / Q000379:methods*