Category: New Technology: Stones

MP5-21 - Clinical Ureteral Injury Due to Passage of a Ureteral Access Sheath: Impact of the Ureteral Access Sheath Force Sensor

Fri, Sep 21
10:00 AM - 12:00 PM

Introduction & Objective :

Ureteral injury is a major concern with regard to deployment of an ureteral access sheath (UAS). The amount of force that results in clinical ureteral injury has yet to be defined. In a previous study, using a novel UAS Force Sensor (UAS-FS) developed at UC Irvine (Figure 1), we noted that a peak force of 8 Newtons (N) resulted in splitting of the porcine ureter. Herein, we present our initial clinical findings using UAS-FS during routine ureteroscopy.


Methods :

UAS deployment force was measured in 35 patients using UAS-FS under fluoroscopic control by 4 surgeons. Tamsulosin was given for up to one week in two-thirds of these patients in an attempt to induce a state of ureteral relaxation. Continuous UAS-FS measurements were recorded from urethral meatus until the UAS reached the ureteropelvic junction/renal pelvis. A level of 7-8N was used as the upper limit of applied force. If this level was reached, a fluoroscopic image was obtained and the UAS was removed and exchanged for a smaller UAS. Ureteroscopic evaluation of the ureter at the end of each case was recorded using the post-ureteroscopic lesion scale (PULS).


Results :

Among 35 patients, there were 41 UAS deployments (Table 1). The 16F UAS could be passed at ≤ 8N in 61% of patients; in the remainder, 8N was reached during the initial passage of the 16F UAS.  In each of the latter cases, the 16F was removed; a 14F was passed in 13 cases and an 11.5F in 2 cases (Table 1). The mid ureter location was where the maximum peak pressure (17%) was most commonly recorded. The mean PULS grade was 0.77 (0-3). The solitary PULS 3 injury occurred in a patient in whom three UAS insertions were serially tried 16F, 14F, and 11.5F at peak forces of 8.1N, 8.9N, and 5.0N, respectively; at two months there was no symptomatic nor radiographic evidence of a stricture.


Conclusions :

The UAS-FS accurately measured UAS insertion force in a clinical setting. Despite routine passage of 14F and 16F UAS, limiting the insertion force to < 8N resulted in a PULS score ≤ 2. 

Kamaljot S. Kaler

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

Zachary A. Valley

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

Renai Yoon

University of California, Irvine
Orange, California

Roshan M. Patel

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