Application of Suctioning Ureteral Access Sheath during Flexible Ureteroscopy for Renal Stones Decreases the Risk of Postoperative Systemic Inflammatory Response Syndrome

The Evaluation of Intrarenal Pressure Using a Novel Single-Use Flexible Ureteroscope with Live Intrarenal Pressure Monitoring-An Experimental Study in Porcine Models

(1) Background: This study aims to evaluate how different irrigation settings and the use of ureteral access sheaths (UASs) of varying sizes impact intrarenal pressure (IRP) during flexible ureteroscopy (fURS) procedures in pigs. (2) Methods: This study utilized three anesthetized female pigs. A novel flexible ureteroscope with the ability to continuously record live intrarenal pressure was used to perform ureteroscopy in different settings. Ureteroscopy was performed without UAS and with the use of 11/13 and 12/14 UAS at the ureteropelvic junction. Two different irrigation methods were employed for each parameter: one using gravity flow and the other using manual pumping with a commercial pump. IRP was also recorded with the presence of a laser fiber or lithotripsy basket. (3) Results: The recorded mean IRP during flexible URS without UAS was 28.25 (±11.2) under gravity irrigation; 35.46 (±10.08) under manual pumping; 22.5 (±3.05) and 30.75 (±5.79) with a laser fiber under gravity irrigation and manual pumping, respectively; and 16.45 (±1.27) and 17.27 (±3.69) with a lithotripsy basket under gravity irrigation and manual pumping, respectively. With an 11/13 UAS, the mean IRP was 15.41 (±8.57) and 19.33 (±4.26) under gravity and manual pumping irrigation, respectively; 14.56 (±2.50) and 18.64 (±5.13) with a laser in each irrigation setting, respectively; and 13.10 (±3.39) and 13.86 (±4.63) with a lithotripsy basket, respectively. With a 12/14 UAS, the mean IRP was 7.64 (±3.08) and 9.25 (±1.42) under gravity and manual pumping irrigation, respectively; 9.50 (±6.04) and 10.28 (3.46), respectively, in each setting when the laser fiber was used; and 5.32 (±1.57) and 6.26 (±1.79), respectively, when the lithotripsy basket was inserted. (4) Conclusion: Novel flexible ureteroscopes with integrated pressure sensors are both a feasible and reliable tool during fURS, giving the surgeon the ability to live-track the IRP. The results of the IRP measurements with and without UAS are in accordance with the current literature and exhibit a consistent pattern with previous studies.

Scoping Review of Experimental and Clinical Evidence and Its Influence on Development of the Suction Ureteral Access Sheath

The ureteral access sheath (UAS) has been a boon and a bane in flexible ureteroscopy (FURS), with its merits and demerits well established. Its design and dimensions were instrumental in reshaping the way flexible scopes were used and were key adjuncts to establishing retrograde intrarenal surgery (RIRS) as a standard of care in the endourological management of renal stones. With the ever-changing landscape of RIRS over the decades shaped by technological advancements in lasers and flexible scopes, the UAS has also continuously evolved. The utility of suction in endourology has recently changed the way RIRS is performed and is a game changer for FURS outcomes. With strong clinical and experimental evidence to support its use, the UAS has undergone a transformative change in the recent past, with its ability to monitor intrarenal pressure and provide a superior vacuum-cleaner effect that improves the trifecta of RIRS, namely an improved single-stage stone-free rate (SFR), minimise complications, and reduce reinterventions. Our comprehensive review outlines the key clinical and experimental evidence and traces the developments that were key to modifying the traditional UAS into a flexible and navigable suction ureteric access sheath (FANS) and highlights how the design and modifications, in turn, influence the ability to push the boundaries of RIRS.

Retrograde Intrarenal Surgery for Lithiasis Using Suctioning Devices: A Shift in Paradigm?

New suction endoscopes, ureteral access sheaths (UAS) and catheters aim to improve the efficacy of flexible ureteroscopy and optimize its safety. Suction UAS with non-flexible tips have shown promising results, especially in maintaining low intrarenal pressure, but also in removing small debris and reducing the "snow globe" effect. In addition, suctioning UAS with a flexible tip offers the advantage of being able to be navigated through the pyelocaliceal system to where the laser lithotripsy is performed. It can also remove small stone fragments when the flexible ureteroscope is retracted, using the Venturi effect. Direct in-scope suction (DISS) involves aspirating dust and small stone debris through the working channel of a flexible ureteroscope, thus regulating intrarenal pressure and improving visibility. Steerable aspiration catheters are other devices designed to increase stone clearance of the pyelocaliceal system. They are inserted under fluoroscopic guidance into every calyx after retraction of the flexible ureteroscope, alternating irrigation and aspiration to remove dust and small gravels. Combining flexible-tip suction UAS and the DISS technique may offer some advantages worth evaluating. The advantage of using these instruments to achieve a low intrarenal pressure was demonstrated. The true practical impact on the long-term stone-free status is a matter requiring further studies.

Comparison of traditional and suctioning ureteral access sheath during retrograde intrarenal surgery in the treatment of renal calculi

PURPOSE

This study aims to compare the efficiency and clinical outcomes between the suctioning ureteral access sheath (UAS) group and the traditional UAS group during retrograde intrarenal surgery (RIRS) for kidney stones and explore the impact of suctioning UAS on postoperative infectious complications.

METHODS

We retrospectively reviewed the clinical data of 162 patients with kidney stones who underwent RIRS with a traditional UAS (n = 74) or a suctioning UAS (n = 71) between March 2021 and May 2023.

RESULTS

The mean operative time in suctioning UAS group (39.03 ± 18.01 s) was significantly shorter than that (49.73 ± 20.77 s) in the traditional UAS group (P = 0.037). The mean postoperative hospital stay was significantly shorter in the suctioning UAS group (1.57 ± 0.82d) compared with the traditional UAS group (2.30 ± 1.6 2 d) (P = 0.032). The instant SFRs were significantly higher in the suctioning UAS group (88.73%) than in the traditional UAS group (75.68%) (P = 0.040). The overall SFR in suctioning UAS group (92.96%) was slightly higher than the traditional UAS group (85.14%). The incidence of overall complications was significantly higher in the traditional UAS group (35.14%) than in the suctioning UAS group (16.90%) (P = 0.013). In multivariate analysis, female patients (OR 0.053, P = 0.018), positive urine WBC (OR 10.382, P = 0.034), operative time > 60 min (OR 20.231, P = 0.032), and the application of traditional UAS (OR 0.042, P = 0.017) were independent risk factors associated with infectious complications.

CONCLUSION

We demonstrated that suctioning UAS provided a higher instant SFR and fewer postoperative infectious complications during RIRS, and patients with predictable risk factors for infectious complications could potentially benefit from the use of the suctioning UAS.

Does preoperative silodosin administration facilitate ureteral dilatation during flexible ureterorenoscopy? A randomized clinical trial

PURPOSE

To assess whether preoperative administration of silodosin can facilitate the placement of ureteral access sheath (UAS) prior to flexible ureteroscopy (F-URS) and reduce the occurrence of ureteric injury in challenging cases.

METHODS

This prospective randomized clinical trial was carried out on 147 patients diagnosed with upper ureteric stone or stone kidney, non-stented. The patients were randomly divided into two equal groups. Group A (silodosin group) included patients in whom F-URS was done with daily preoperative intake of 8 mg silodosin for 1 week and group B (placebo/control group) included patients in whom F-URS was done with daily preoperative intake of placebo tablets.

RESULTS

In group A, a total of 23 (33.3%) experienced ureteral wall injury following UAS insertion, while in group B, this occurred in 40 patients (59.7%). There was a statistically significant difference in the grade of ureteral wall injury between the two groups (P < 0.001). In the multiple regression analysis, age, operative time and silodosin were found to be significant risk factors for ureteral wall injury (P = 0.007, 0.041 and < 0.001, respectively).

CONCLUSIONS

The administration of silodosin prior to retrograde intrarenal surgery (RIRS) effectively prevented significant ureteral wall damage and reduced initial postoperative discomfort.

Experimental and clinical applications and outcomes of using different forms of suction in retrograde intrarenal surgery. Results from a systematic review

OBJECTIVE

To identify the latest advances in suction devices and evaluate their effect in Retrograde intrarenal surgery (RIRS) and ureteroscopy for stones.

BASIC PROCEDURES

A systematic literature search was performed on 4th January 2023 using Scopus, PubMed, and EMBASE. Only English papers were included; both pediatric and adult studies were accepted. Duplicate studies, case reports, letters to the editor, and meeting abstracts were excluded.

MAIN FINDINGS

Twenty-one papers were selected. Several methods have been proposed for suction use in RIRS, such as through the ureteral access sheath or directly to the scope. Artificial intelligence can also regulate this system, monitoring pressure and perfusion flow values. All the proposed techniques showed satisfactory perioperative results for operative time, stone-free rate (SFR), and residual fragments. Moreover, the reduction of intrarenal pressure (induced by aspiration) was also associated with a lower infection rate. Even the studies that considered kidney stones with a diameter of 20 mm or higher reported higher SFR and reduced postoperative complications. However, the lack of well-defined settings for suction pressure and fluid flow prevents the standardization of the procedure.

CONCLUSION

Aspiration device in the surgical treatment of urinary stones favours a higher SFR, reducing infectious complications, as supported by the included studies. RIRS with a suction system provided to be a natural successor to the traditional technique, regulating intrarenal pressure and aspirating fine dust.

Comparison of traditional and novel tip-flexible suctioning ureteral access sheath combined with flexible ureteroscope to treat unilateral renal calculi

OBJECTIVES

To compare the safety and efficacy of novel tip-flexible suctioning ureteral access sheath (NTFS-UAS) and traditional ureteral access sheath (T-UAS) combined with flexible ureteroscope for treating unilateral renal calculi.

MATERIALS AND METHODS

The clinical data of 214 patients with unilateral renal calculi treated by NTFS-UAS (n = 102) and T-UAS (n = 112) combined with flexible ureteroscope from August 2021 to April 2022 were analyzed retrospectively. Demographic characteristics, stone-related parameters, operative time, stone-free rates (SFR), hospitalization time and complication rate (CR) were analyzed.

RESULT

No significant difference was observed between the two groups in terms of demographic characteristics, stone-related parameters, intraoperative CR, and hospitalization time. The operative time of NTFS-UAS group was significantly shorter than T-UAS group (55.25 ± 11.42 min vs. 59.36 ± 15.59 min; P = 0.028). The NTFS-UAS group obtained significantly higher SFR on 1 day postoperatively (86.3% vs. 75.0%; P = 0.038), and higher SFR on 30 days postoperatively than T-UAS group (91.2% vs. 81.3%; P = 0.037). The hemoglobin loss of NTFS-UAS group (- 0.54 ± 0.69 g/dl) was significantly lower than T-UAS group (- 0.83 ± 0.66 g/dl; P = 0.002). There was a significantly lower incidence of overall CR (11.8% vs. 22.3%; P = 0.041), and infectious CR (8.8% vs. 18.8%; P = 0.037) in the NTFS-UAS group.

CONCLUSION

Compared to T-UAS combined with flexible ureteroscope for treating unilateral renal calculi, NTFS-UAS had superiority in higher SFR on 1 day and 30 days postoperatively. Shorter operation time, lower hemoglobin loss, lower incidences of overall and infectious CR were observed in NTFS-UAS group.

REGISTRATION NUMBER AND DATE

ChiCTR2300070210; April 5, 2023.

A Novel Distal Active Flexible Vacuum-assisted Ureteric Access Sheath in Retrograde Intrarenal Surgery

INTRODUCTION

Retrograde intrarenal surgery (RIRS) is one of the primary treatments for renal stones. The ureteral access sheath (UAS) was widely used in RIRS.1,2 The aim of this paper is to introduce a new UAS, the distal active flexible vacuum-assisted ureteral access sheaths (DAFV-UAS), for the renal calculus during RIRS.

CASE PRESENTATION

A 56-year-old female presented to the outpatient clinics of our hospital with a left renal lower calyx stone. Abdominal CT demonstrated that the left kidney's lower calyx stone size was 10.54 ×10.38 mm, and the mean Hounsfield density was 965HU. After adequate anti-infective treatment, the DAFV-UAS was used in RIRS. No perioperative complications were observed. The left renal stone had been cleared completely.

DISCUSSION

The DAFV-UAS (10/12.5 Fr, 38 cm, creek, Jiangsu, China) includes a good flexibility and deformability tube at the tip, about 10 cm long. It has an active bending function, negative pressure suction function, and the function of convenient flexible ureteroscopy (f-URS) entry and exit of the ureter.3 In this case, the f-URS adopted a 7.5 Fr single-use digital f-URS. The Irrigation method was automated irrigation system, and the flow was 30 mL/min. The suction level was 0.02mpa. With the help of DAFV-UAS, the field of view is always clean, the small gravel particles can be sucked out from the sheath gap, and the larger gravel particles are sucked out by withdrawing the scope intermittently.

CONCLUSION

DAFV-UAS is a promising new device which allows for negative pressure suction directed right at a renal stone and efficient and effective stone clearance.

A Feasibility Study on Clinical Utility, Efficacy and Limitations of 2 Types of Flexible and Navigable Suction Ureteral Access Sheaths in Retrograde Intrarenal Surgery for Renal Stones

OBJECTIVE

To evaluate stone-free rate, device maneuverability, and complications after retrograde intrarenal surgery (RIRS) using 2 different sizes of flexible and navigable suction ureteral access sheaths (FANS).

METHODS

A retrospective analysis was performed for patients who underwent RIRS for renal stones of any size, number, and location between November 2021 and October 2022. Group 1 had FANS of 12 French. Group 2 had FANS of 10 French. Both sheaths have a Y-shaped suction channel. Tip of 10 French FANS has 20% more flexibility. Lithotripsy was achieved using either thulium fiber or high-power holmium lasers. A 5-point Likert scale was used to assess the performance of each sheath.

RESULTS

There were 16 patients in Group 1 and 15 patients in Group 2. Baseline demographics and stone parameters were similar. Four patients in Group 2 had the same session bilateral RIRS. Sheath insertion was successful in all renal units but one. Ten French FANS had a higher percentage of excellent scores for ease of use, manipulation, and visibility. Neither of the sheaths had an average or difficult rating for all evaluation scales. A fornix rupture requiring prolonged stenting occurred in group 2. All patients were discharged within 24 hours of surgery. One patient in each group visited the emergency department (analgesic treatment). There were no infectious complications. At 3 months, a computed tomography scan showed that the absence of residual fragments >2 mm was significantly higher in Group 2 (94.7% vs 68.8%, P = 0.01).

CONCLUSION

The 10 Fr FANS showed a higher stone-free rate. There was no infectious complication using both sheaths.

Optimizing Outcomes in Flexible Ureteroscopy: A Narrative Review of Suction Techniques

OBJECTIVE

The aim of this review is to summarize the existing suction systems in flexible ureteroscopy (fURS) and to evaluate their effectiveness and safety.

METHODS

A narrative review was performed using the Pubmed and Web of Science Core Collection (WoSCC) databases. Additionally, we conducted a search on the Twitter platform. Studies including suctions systems in fURS were included. Editorials, letters and studies reporting intervention with semirigid ureteroscopy, PCNL and mPCNL were excluded.

RESULTS

A total of 12 studies were included in this review. These studies comprised one in vitro study, one ex vivo study, one experimental study and eight cohort studies. The Pubmed and WoSCC searches identified three suction techniques (Irrigation/Suctioning system with control of pressure, suction ureteral access sheath (sUAS) and direct in scope suction (DISS)), and the Twitter search identified four of them. The overall results showed that suction is an effective and safe technique that improves stone-free rates, reduces operative time and limits complication rates after fURS.

CONCLUSIONS

The use of suctioning during common endourological procedures has been shown to improve safety and efficacy in several indications. However, randomized controlled trials are needed to confirm this.

A nomogram for predicting postoperative urosepsis following retrograde intrarenal surgery in upper urinary calculi patients with negative preoperative urine culture

Retrograde intrarenal surgery (RIRS) is one of the main surgical methods for upper urinary calculi, but severe complications of infection may occur after surgery. This study aimed to establish and validate a preoperative nomogram for predicting postoperative urosepsis following retrograde intrarenal surgery to treat upper urinary calculus in patients with a negative preoperative urine culture. We retrospectively recruited 1767 patients with negative preoperative urine cultures who underwent retrograde intrarenal surgery to treat upper urinary calculi from January 2017 to April 2022. The independent risk factors for urosepsis include a solitary kidney, positive urine nitrite, operative time ≥ 75 min, history of recurrent urinary tract infections, and history of diabetes were identified by univariate analysis and multivariate binary logistic regression analysis, which construct a nomogram. The receiver operating characteristic curve of the nomogram for predicting urosepsis was 0.887 in the training cohort and 0.864 in the validation cohort, respectively. The calibration curve and decision curve analysis demonstrated great consistency and clinical utility of the nomogram. Therefore, the nomogram combining preoperative independent risk factors can predict the probability of a postoperative urosepsis following retrograde intrarenal surgery in patients with a negative preoperative urine culture, which could help urologists take preventive measures in advance after surgery to avoid more serious complications of infection.