Category: New Technology: Stones
Introduction & Objective : Pyelovenous backflow created by elevated intrarenal pressures may lead to increased risk of bacteremia and sepsis during ureteroscopy. Herein we report the use of a cardiac pressure guide wire to evaluate intracalyceal pressures during flexible ureteroscopy.
Eight patients with nephrolithiasis were recruited. Each participant underwent retrograde pyelography at the time of uretroscopy and patients with severe hydronephrosis were excluded. A Verrata pressure guide wire (Phillips Volcano Corporation, Amsterdam, Netherlands) with a flexible tip and an overall diameter of 1Fr and length of 185cm was passed through the working channel of a dual lumen flexible ureteroscope (Richard Wolf USA, Vernon Hills, IL) (Figure 1A) with the irrigation pressure maintained at 150mmHg through the second channel. The pressure guide wire was extended 1cm beyond the tip of the ureteroscope; pressure measurements were taken in the upper pole, middle, and lower pole calyces (Figure 1B). Pressure measurements were taken with and without an ureteral access sheath. Infundibular widths were determined from the retrograde pyelography images and measured with Vitrea software (Vital Images, Minnetonka, Minnesota).
The Verrata pressure guide wire was used in eight patients (2 male/6 female) with a mean (± SD) age of 58.1 (± 11.3) years. A pre-existing 6Fr ureteral stent was in place at the time of surgery in three (38%) cases. The mean (± SD) widths of the upper pole, middle, and lower pole major infundibulae were 9.1 (± 5.3) mm, 6.4 (± 3.1) mm, and 9.5 (± 3.4) mm, respectively. The ureteral access sheath was 14Fr (3 cases) and 16Fr (5 cases). The intracalyceal pressure was lower in each region of the kidney when an ureteral access sheath was used (Table 1). Using a 16Fr access sheath resulted in the lowest intracalyceal pressures in all regions of the kidney (Figure 2).
Intracalyceal pressure is lower when a ureteral access sheath is utilized during flexible ureteroscopy; the larger access sheaths provide the lowest intracalyceal pressure thereby reducing the risk of renal backflow.
Roshan Patel– Assistant Clinical Professor, University of California, Irvine, Department of Urology, Orange, California
Michael Owyong– Orange, California
Maged Ayad– Orage, California
Martin Hofmann– Orange, California
Jaime Landman– Professor and Chair, Department of Urology, University of California, Irvine, Orange, CA, Orange, California
Ralph Clayman– Professor, University of California, Irvine, Department of Urology, Orange, California
Assistant Clinical Professor
University of California, Irvine, Department of Urology
Professor and Chair
Department of Urology, University of California, Irvine, Orange, CA
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.