WCE 2018: Comparison of Intrarenal Pelvic Pressure Levels During Flexible Ureteroscopy, Mini-Percutaneous Nephrolithotomy and Standard Percutaneous Nephrolithotomy in a Kidney Model

Paris, France (UroToday.com) Given that irrigation and endoscopic instrumentation increase the intrarenal pelvic pressure (IPP) during procedures such as flexible ureteroscopy (fURS) and percutaneous nephrolithotomy (PCNL), Dr. Doizi and his colleagues sought to quantify which combination of irrigation pressures and instrumentation result in the most notable IPP changes.  

Using a silicone model of the urinary tract (from kidneys proximally to urethra distally), the investigators measured IPP using a PressureWire placed in the renal pelvis and using the following combinations of instrumentation, each at 40 cmH2O and 193 cmH2O:

UroTodayWCE2018 Comparison of Intrarenal Pelvic Pressure Levels During Flexible Ureteroscopy Mini Percutaneous Nephrolithotomy and Standard Percutaneous Nephrolithotomy in a Kidney Model 3
The investigators noted that IPP during fURS was always higher than that for mini- or standard PCNL. For fURS, they noted that the presence of a UAS or 273 Âμm laser fiber in the working channel both lead to decreased IPP at any irrigation pressure, and the lowest IPP pressure overall was seen when a UAS was combined with a laser fiber in the working channel at 40 cm H2O. While the use of a UAS during mini-PCNL resulted in a decreasing IPP with an increase in UAS size at all irrigation pressure settings.

The use of UAS as a core feature of these experiments sparked a lively discussion about the potential trade-off between the decreased IPP when using an access sheath (due to improved outflow) versus the increased ureteral wall pressure and potential for ureteral ischemia. Dr. Doizi suggested choosing a UAS that optimizes outflow but is not unnecessarily large so as to minimize ureteral damage. Another audience member noted that he was part of a study that found a 10/12 Fr UAS to be optimal in most cases with no significant change in ureteral blood flow when a UAS that is within 1.5Fr of a 10/12 Fr UAS was used. 

The authors concluded that fURS result in higher IPP than mini-PCNL and standard PCNL, regardless of instrumentation and irrigant pressure.

Presented by: Steeve Doizi, MD, Urologist, Sorbonne University, Clinical Research Group, Hôpital Tenon, Paris, France, Paris, Ile-de-France, France
Co-Authors: Audrey Uzan, 1 Etienne Keller, 1 Vincent De Coninck,2 Maria Rodrigues-Monsalve Herrero,3 Olivier Traxer1
Author Affiliation:
1. Sorbonne University, Clinical Research Group
2. Algemeen Ziekenhuis Klina
3. University Hospital Puerta de Hierro, Majadahonda

Written by: Frank Jefferson, Department of Urology, University of California-Irvine, medical writer for UroToday.com at the 36th World Congress of Endourology (WCE) and SWL - September 20-23, 2018 Paris, France