EAU 2017: Impact Of Preoperative A-adrenergic Antagonists On Ureteral Access Sheath Insertion Force And The Upper Limit Of Force To Avoid Ureteral Mucosal Injury: A Randomized Controlled Study
Koo and authors have assessed a very important question in contemporary management of ureteral and kidney stones with URS. In order to avoid any potential tears and injuries to the ureter and renal pelvis during URS, the use of ureteral access sheath is commonly recommended. Additionally, it is well known that UAS also helps to maintain adequate hydrostatic pressure during URS. However, there is a risk of ureteral injury if the size of UAS is too large or too much of force is applied during deployment leading to increased risk of ureteral injury. Authors hypothesized that the use of alpha-blockers will facilitate the relaxation of the smooth muscle of the ureter and thereby help to deploy the UAS without preoperative stenting of the patient. They performed a randomized controlled trial to investigate the efficacy of preoperative alpha-blockade on reducing UAS insertion forces (UASIF). Additionally, they measured the maximum amount of pressure applied during the UAS deployment without causing any damage to the ureter.
During the period of December 2015 and October 2016, a total of 88 patients with ureteropelvic junction or renal pelvis stones undergoing for URS were prospectively enrolled in a randomized fashion. Patients were randomly assigned to a control group (n=37) who did not receive any medication or to an experimental group who received an alpha-blocker (tamsulosin, 0.4 mg) for seven days prior to URS (n=39). Any pre-stented patients were excluded from randomization (n=12). A homemade UASIF gauge was developed and validated to measure the maximal UASIF at the ureterovesical junction (UVJ) and the proximal ureter. The degree of mucosal injury was recorded using validated assessment tool.
The study demonstrated that UASIF of the alpha-blockade group was significantly lower compared to patients in control group at the UVJ (260±180 vs. 524±237; p=0.017). However, these results were not consistent when the pressures were measured at the proximal ureter (367±175 vs. 647±294; p=0.054). The alpha-blockade group exhibited comparable UASIF with the pre-stented group at the UVJ (260.1±180.2 g vs. 99.8±19.9 g; p=0.149) and the proximal ureter (367.2 ± 175.2 g vs. 131.4±75.2 g; p=0.081).
According to the presentation from the authors, the rate of mucosal injury was lower in the alpha-blockade group compared to patients in the control group (p=0.02). Mucosal injury (≥grade 2) did not occur in cases with UASIF <600 g. UASIF was lower in females and patients aged ≥70 years compared to the counterparts (p=0.008 and p=0.021, respectively). Female gender and preoperative alpha-blockade were independent predictors of lower risks of ureteral injury.
This is an important study demonstrating the efficacy of alpha-blockers in patients undergoing URS and UAS deployment. Authors were able to define a threshold for UAS force during the procedure. Authors concluded that preoperative use of selective alpha blockers mimic the effect of pre-stenting and reduces maximum UASIF and consequent risk of ureteral injury. If the UASIF exceeds 600g, the procedure could be terminated with stent placement and followed later by pre-stented URS.
Speaker(s): Dr. Koo, MD
Authors: Koo K.C.1, Lee D.H.3, Yoon J.H.2, Park N.-C.2, Lee K.S.1, Kim D.K.1, Kim J.C.1, Oh K.T.1, Heo J.E.1, Cho K.S.1, Hong C.H.1, Chung B.H.1
at the #EAU17 - March 24-28, 2017- London, England