Category: New Technology: Miscellaneous

MP27-20 - Measuring Deployment Forces During Passage of An Ureteral Access Sheath in the Porcine Ureter: “If it don’t go easy, it don’t go at all.”*

Sun, Sep 23
10:00 AM - 12:00 PM

Introduction & Objective :

Concerns regarding ureteral injury have limited the more widespread use of an ureteral access sheath (UAS) during ureteroscopy. In this porcine study, the UC Irvine developed, UAS Force Sensor (UASFS) (Figure 1) was used to define the threshold deployment force at which an ureteral injury would occur.


Methods :

The UASFS was used to measure UAS deployment forces in six juvenile female Yorkshire pigs (average size 19.5 kg (16 – 22 kg)). Under fluoroscopic guidance, ureteral dilators (6-9F) along with a variety of UAS and corresponding obturators (9.5F-16F)were sequentially advanced into one of the ureters in each pig. In the opposite ureter, after 8/10F dilation, the 12/14F UAS was deployed without any intervening sequential dilation. Force was measured continuously from the urethra to placement of the UAS in the renal pelvis. Ureteroscopic evaluation after each dilation was recorded using the post ureteroscopic lesion scale (PULS 0 = no injury, 5 = complete transection of the ureter).   


Results :

In 5/6 juvenile pigs, ureters selected for 12/14 UAS deployment without prior sequential dilation were injured (PULS ≥ 3) at a threshold force of 4.84N (Figure 2). Sequential dilation had a higher threshold for PULS > 3 at 5.56N. Overall, injury of PULS > 3 was routinely noted when the force applied exceeded 7.5N.


 


Of note, the force leading to injury was less among juvenile pigs than in an adult pig (force of 8N) or clinically (force of 8-9N).  


Conclusions :

The UASFS reliably measures force while deploying a UAS. Significant ureteral injury can routinely be avoided if the applied force is < 4.84N; PULS > 3 routinely occurred when forces exceeded 7.5N. Sequential dilation may be beneficial.  

Kamaljot S. Kaler

Clinical Assistant Professor
University of California, Irvine; University of Calgary
Orange, California

Roshan M. Patel

Assistant Clinical Professor
University of California, Irvine, Department of Urology
Orange, California

Mitchell L. O'Leary

Clinical Researcher
University of California, Irvine, Department of Urology
Orange, California

Vinay Cooper

Clinical Researcher
University of California, Irvine, Department of Urology
Orange, California

Renai Yoon

University of California, Irvine
Orange, California

Christina Hwang

University of California, Irvine
Orange, California

Zhamshid Okhunov

University of California, Irvine, Department of Urology
Orange, California

Michael Klopfer

University of California, Irvine
Orange, California

Jaime Landman

Professor and Chair
Department of Urology, University of California, Irvine, Orange, CA
Orange, California

Professor Landman completed his medical training at Columbia University. He then completed his Urology residency at Mt. Sinai Hospital in New York before moving to St. Louis to complete his minimally invasive urology training at Washington University under the guidance of Dr. Ralph Clayman. Dr. Landman’s fellowship training focused on the minimally invasive treatment of renal diseases.

Prof. Landman focuses on developing new clinical approaches to minimally invasive and more effective treatments for surgical renal diseases such as renal cell carcinoma, urolithiasis and ureteropelvic junction obstruction. For the past decade, his clinical practice has been focused almost exclusively on the minimally invasive management of kidney disease with a focus on renal oncology and urolithiasis.

Since 2002 Dr. Landman has directed an active minimally invasive urology laboratory. His laboratory has focused largely on innovative minimally invasive solutions in the diagnosis and treatment of urologic malignancies, kidney stones and the development of minimally invasive surgical technologies.

A major focus of Dr. Landman’s efforts has been the didactic and technical training of students, residents and fellows. Dr. Landman has had an active role in medical student and resident education since 2001. Since 2002 Dr. Landman has been actively directing the Endourology sanctioned clinical and research fellowship, and he was until recently the program director for the UC Irvine Urology residency. Dr. Landman engendered and currently directs the LIFT (Leadership Innovation Fellowship Training) program at UC Irvine and has focused on helping medical students become academic leaders in Urology.

A current focus of Dr. Landman’s research remains didactic and technical training for students, residents and fellows. His research team continues to develop novel strategies for surgical education.

Ralph V. Clayman

Professor
University of California, Irvine, Department of Urology
Orange, California