Presentation Authors: Shlomi Tapiero*, Orange, CA, Kamaljot S. Kaler, Calgary, Canada, Linda M. Huynh, Mitchell L. O’Leary, Vinay G. Cooper, Zachary A. Valley, Renai H. Yoon, Roshan M. Patel, Zhamshid Okhunov, Orange, CA, Michael Klopfer, Irvine, CA, Jaime Landman, Ralph V. Clayman, Orange, CA
Introduction: Ureteral injury is a potential complication of ureteral access sheath (UAS) deployment. The amount of force that results in clinical ureteral injury has yet to be defined. Herein, we present our clinical experience using a novel UAS Force Sensor (UAS-FS) during routine ureteroscopy.
Methods: UAS deployment force was measured with a UAS-FS, developed in collaboration with engineers at our institution (Figure 1). Continuous UAS-FS measurements were recorded from the urethral meatus until either the UAS reached the desired ureteral deployment site or 10 Newtons (N) was recorded. A 16 Fr UAS was used in each initial attempt. Fluoroscopic images were obtained at 2 N, 4 N, 6 N, 8 N, and 10 N. In general, if 8 N was reached, the 16 Fr UAS was exchanged for a 14 Fr or 11 Fr UAS. Ureteroscopic assessment of the ureter at the end of each case was quantitated using the post-ureteroscopic lesion scale (PULS).
Results: UAS deployment force was measured in 72 ureters among 65 patients. The 16 Fr UAS was deployed in 51 ureters (71%) at a maximal force of 5.4 N (1.9-11.6). In the remaining cases, a 14 Fr or 11 Fr UAS was passed in 19% and 10% with a maximal force of 4.6 N (1.4-9.1) and 3.1 N (1.2-5.0), respectively (p=0.08). Maximum peak force was most commonly recorded (31%) at the distal ureter. PULS 0, 1, and 2 were recorded in 31%, 36%, and 15% of cases, respectively (not recorded in 17%) (Table 1). A single PULS 3 was noted following deployment of a 14 Fr UAS at a peak pressure of 8.9 N. Of note, when the force applied was < 5 N, the PULS score was consistently â‰¤1. On multivariate analysis, successful deployment of a 16 Fr UAS was associated with pre-stented ureters (p=0.04). Preoperative treatment with tamsulosin was not associated with lower PULS (p=0.32), lower peak force applied (p=0.39), or with an increase in deployment of the 16 Fr UAS (p=0.45).
Conclusions: Using an UAS-FS, ureteral access deployment force could be continuously measured in the clinical setting. Limiting the deployment force to < 5 N consistently resulted in a PULS score of â‰¤1.