Ex Vivo Porcine Kidney Model for Evaluating Flow-Pressure Dynamics and Stone Retrieval in Suction-Assisted Retrograde Intrarenal Surgery

Summary

This protocol establishes an ex vivo porcine kidney platform for controlled, repeatable quantification of intrarenal pressure and stone pull-out time across different irrigation pressures, suction pressures, and ratios of endoscope-sheath diameter.

Abstract

Retrograde intrarenal surgery (RIRS) using a suction ureteral access sheath (UAS) has become an effective approach for renal stone management. However, standardized experimental models capable of simultaneously controlling and evaluating relevant parameters, including irrigation pressure, suction pressure, and the ratio of endoscope-sheath diameter (RESD), remain limited. The aim of this study is to propose an ex vivo porcine kidney model designed to enable controlled and repeatable evaluation of flow–pressure conditions with suction UAS. The protocol utilized fresh cadaveric porcine kidneys placed in a fixed container system, with the suction UAS positioned at the upper pole calyx, and artificial stones mimicking calcium oxalate monohydrate introduced into the collecting system. An automated pressure-control pump system enabled precise regulation of irrigation and suction pressures. Intrarenal pressure (IRP) was continuously recorded for 1 min, and pull-out time (POT) was measured repeatedly under each RESD and pressure setting. The coefficient of variation (CV) and intraclass correlation coefficient (ICC) were calculated to assess measurement variability and reliability. The model demonstrated distinct IRP responses across different RESD and pressure conditions, including values exceeding 40 mmHg. POT measurements varied according to pressure settings, reflecting sensitivity to changes in flow–pressure conditions. CV analysis showed relatively narrow variability across most conditions, while ICC analysis demonstrated moderate reliability for single measurements and high reliability for averaged repeated measurements. Overall, this ex vivo porcine kidney model provides a standardized ex vivo reference for RIRS by presenting objective and reliable repeated measurement data using a suction UAS and a flexible ureteroscope.

Introduction

Retrograde Intrarenal Surgery (RIRS) stands as a primary minimally invasive approach for managing renal stones^1,2,3. A recent technical advancement in RIRS is the development of the suction ureteral access sheath (UAS), which has introduced an adjunctive approach to stone retrieval based on controlled irrigation and suction^4,5,6,7.

The primary challenge in utilizing suction UAS is balancing stone extraction speed with the....

Protocol

This experimental protocol using a cadaveric porcine kidney was deemed exempt from the Institutional Animal Care and Use Committee (IACUC) of Seoul National University Hospital. The reagents and the equipment used are listed in the Table of Materials.

1. Preparation of the porcine kidney model

NOTE: See Figure 1.

1. Obtain fresh kidneys from deceased pigs at an authorized slaughterhouse within 6 h of death. Transport and store the kidneys at room temperature until the experiment.
   NOTE: Cadaveric porcine kidneys should be used within 2....

Results

The outer diameter of the flexible ureteroscope was measured at both the distal tip and midshaft using a digital caliper. The measured outer diameters were 7.5 F, 9.0 F, and 9.5 F, respectively, consistent with the product catalog. No difference was observed between distal tip and midshaft measurements, confirming that the instrument dimensions were uniform and suitable for reliable RESD calculation (see Figure 2).

IRP was recorded continuously for 1 min at 5 s in.......

Discussion

This protocol was designed to establish a controlled experimental platform for evaluating flow–pressure conditions during RIRS using a suction UAS. This study provided an ex vivo porcine kidney model capable of systematically controlling irrigation pressure, suction pressure, and RESD settings, while enabling consistent measurement of IRP and POT with statistical validation.

The most critical step in this protocol is to maintain the remnant control settings constant to ensure co.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Flexible-Y Type Negative Suction Sheath	ZSR System Biomedical Technology Co.	ZSR-UAY-1035 ZSR-UAY-1134 ZSR-UAY-1235	Suction ureteral access sheath
FLEX-XC1	KARL STORZ SE & Co.	091271-06	Flexible ureteroscope
HM30S	HugeMed Medical Technical Development Co.	HM30S	Flexible ureteroscope
i-MIMER-sys	ZSR System Biomedical Technology Co.	ZSR-ISP100	Automated pump
JW Digital Calipers	Jongwon Tooling Co.	404-200	Digital caliper
URUS	Dyne Medical Group Inc.	URUS SU 100R	Flexible ureteroscope