Novel Flexible Vacuum-Assisted Ureteral Access Sheath Can Actively Control Intrarenal Pressure and Obtain a Complete Stone-Free Status

Abstract

<b><i>Objectives:</i></b> To compare the safety and effectiveness of a novel flexible vacuum-assisted ureteral access sheath (FV-UAS) and traditional ureteral access sheath (UAS) in simulating retrograde intrarenal surgery (RIRS). <b><i>Materials and Methods:</i></b> A manometric model was established in porcine kidneys to observe the change in intrarenal pressure (IRP) in the FV-UAS and traditional UAS groups at different irrigation fluid velocities of 30, 50, 80, and 100 mL/min. Establish a kidney stone model (with 0.2 g, dry, ≤5 mm stones) to simulate RIRS. A total of 20 porcine kidneys were randomly numbered from 1 to 20 (FV-UAS group, 1 - 10; traditional UAS group, 11 - 20). The stone volume clearance rate and operation time were compared between the two groups. ("<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mstyle><mml:mi>S</mml:mi><mml:mi>t</mml:mi><mml:mi>o</mml:mi><mml:mi>n</mml:mi><mml:mi>e</mml:mi><mml:mi>v</mml:mi><mml:mi>o</mml:mi><mml:mi>l</mml:mi><mml:mi>u</mml:mi><mml:mi>m</mml:mi><mml:mi>e</mml:mi><mml:mi>c</mml:mi><mml:mi>l</mml:mi><mml:mi>e</mml:mi><mml:mi>a</mml:mi><mml:mi>r</mml:mi><mml:mi>a</mml:mi><mml:mi>n</mml:mi><mml:mi>c</mml:mi><mml:mi>e</mml:mi><mml:mi>r</mml:mi><mml:mi>a</mml:mi><mml:mi>t</mml:mi><mml:mi>e</mml:mi></mml:mstyle><mml:mo>=</mml:mo><mml:mstyle></mml:mstyle><mml:mfenced><mml:mrow><mml:mn>1</mml:mn><mml:mo>-</mml:mo><mml:mfrac><mml:mrow><mml:mstyle><mml:mi>R</mml:mi><mml:mi>e</mml:mi><mml:mi>s</mml:mi><mml:mi>i</mml:mi><mml:mi>d</mml:mi><mml:mi>u</mml:mi><mml:mi>a</mml:mi><mml:mi>l</mml:mi><mml:mi>s</mml:mi><mml:mi>t</mml:mi><mml:mi>o</mml:mi><mml:mi>n</mml:mi><mml:mi>e</mml:mi><mml:mi>v</mml:mi><mml:mi>o</mml:mi><mml:mi>l</mml:mi><mml:mi>u</mml:mi><mml:mi>m</mml:mi><mml:mi>e</mml:mi></mml:mstyle></mml:mrow><mml:mrow><mml:mstyle><mml:mi>P</mml:mi><mml:mi>r</mml:mi><mml:mi>e</mml:mi><mml:mi>o</mml:mi><mml:mi>p</mml:mi><mml:mi>e</mml:mi><mml:mi>r</mml:mi><mml:mi>a</mml:mi><mml:mi>t</mml:mi><mml:mi>i</mml:mi><mml:mi>v</mml:mi><mml:mi>e</mml:mi><mml:mi>s</mml:mi><mml:mi>t</mml:mi><mml:mi>o</mml:mi><mml:mi>n</mml:mi><mml:mi>e</mml:mi><mml:mi>v</mml:mi><mml:mi>o</mml:mi><mml:mi>l</mml:mi><mml:mi>u</mml:mi><mml:mi>m</mml:mi><mml:mi>e</mml:mi></mml:mstyle></mml:mrow></mml:mfrac></mml:mrow></mml:mfenced><mml:mo>×</mml:mo><mml:mn>1</mml:mn><mml:mn>0</mml:mn><mml:mn>0</mml:mn><mml:mstyle><mml:mi>%</mml:mi></mml:mstyle></mml:math>"). Stone volume was obtained by CT pre- and postoperatively. <b><i>Results:</i></b> FV-UAS can follow flexible ureteroscopy (f-URS) to cross the ureteropelvic junction (UPJ) and into the renal pelvis and calices. FV-UAS can actively make IRP <10 cmH₂O by adjusting the negative values at different irrigation fluid velocities. The mean residual stone volume of the FV-UAS <i>vs</i> traditional UAS groups was 33.7 <i>vs</i> 92.5 mm³ (<i>p</i> = 0.017). The mean stone volume clearance rates of the FV-UAS <i>vs</i> traditional UAS groups were 98.5% and 95.9%, respectively (<i>p</i> = 0.017). Seven cases achieved complete stone-free status in the FV-UAS group. All patients had residual fragments postoperatively in the traditional UAS group. <b><i>Conclusions:</i></b> FV-UAS can follow f-URS to cross the UPJ and into the renal pelvis and calices, avoiding the interference of UPJ in controlling IRP. FV-UAS can actively control the IRP to be reduced to the desired range by adjusting the negative value under any irrigation fluid velocity. FV-UAS close to the stone can achieve complete stone-free status in RIRS.