Novel syphon ureteric access sheath has the potential to improve renal pressures and irrigant flow

Novel small fragment removal system may improve extraction of renal calculi: an in vitro study

OBJECTIVE

To describe a novel Small Fragment Removal System (SFRS) which is hypothesized to improve stone fragment removal during flexible ureteroscopy in patients with urolithiasis. The SFRS consists of three parts: a Syphon Ureteric Access Sheath (SUAS), a Dual Action Pump (DAP) and an Agitator. This bench assessment aims to assess the SFRS's impact on intra-renal pressure (IRP), irrigant flow rate and stone fragment removal compared to a traditional UAS.

MATERIALS AND METHODS

A validated phantom kidney and fibre optic pressure sensor was used to assess IRP. Standardized irrigation via a flexible ureterorenoscope was instilled through a traditional UAS and compared to the novel SFRS. Both were 11/13Fr in size. Measured minute volume, IRP and percentage of stone fragments removed were compared.

RESULTS

The mean IRP using a traditional UAS and SFRS was 24,3mmHg and 9,4mmHg respectively. The flow rate of the traditional UAS was 25mL/min, compared to 31mL/min with the SFRS attached. During bolus fluid administration using the traditional UAS the maximum IRP increased to 41mmHg, compared to 9,3mmHg with the SFRS attached. A mean of 42,7% (0,103 g of 0,305 g) of weighed dry stones were removed with the traditional UAS compared to 77,6% (0,233 g of 0,299 g) with the SFRS attached, p = 0,017.

CONCLUSIONS

The described Small Fragment Removal System (SFRS) is different from traditional UASs by incorporating a syphoning mechanism. In addition, it has a Dual Action Pump which both boluses and augments the aspiration of irrigant by the Syphon. It further includes a deflectable Agitator to flush out stone fragments.

Comparison of the safety of flexible ureteroscopy with the different irrigation methods in a 3D print kidney model

OBJECTIVE

To compare intrarenal pressure (IRP) and irrigation flow by varying suspended water heights and hand-held pressure pumping during flexible ureteroscopy using an in vitro 3D printed kidney model.

METHODS

A 3D-printed silicone model was used to simulate the kidney. The ureteral access sheath(UAS) was connected to the kidney model and positioned at the ureteropelvic junction. Central venous pressure tubing was used to monitor the pressure in the renal pelvis under different conditions. Sheath sizes of 12Fr and 14Fr were tested with flexible ureteroscope (fURS) sizes of 7.5, 8.5, and 9.5Fr, respectively. The irrigation was gravity-based, with suspended water heights set at 60, 90, 120, 150, and 180 cm. The manual pumping as another set of measurement is used to measure the maximum intrarenal pressure.

RESULTS

Using a 12Fr sheath with a 9.5Fr fURS loading without additional accessories resulted in IRP ranging from 8.4 to 17.5 cmH2O, while manual pumping perfusion pressure exceeded 60 cmH2O. Loading a 200-um laser fiber reduced the pressure to 6.4-10.5 cmH2O, and using a stone basket decreased it to 4.0-5.0 cmH2O. Using a 14Fr sheath with a 9.5Fr fURS resulted in an IRP of 2.5-6.0 cmH2O, compared to 17 cmH2O with manual pumping. With a 12Fr sheath and a 7.5Fr fURS, the IRP ranged from 5.4 to 8.2 cmH2O, while manual pumping resulted in 25.5 cmH2O. With a 14Fr sheath and a 7.5Fr fURS, the IRP ranged from 1.5 to 4.3 cmH2O, and manual pumping resulted in 9.0 cmH2O.

CONCLUSION

When using a UAS in a flexible ureteroscopy, the IRP can be maintained within a safe range with different fURS/UAS combos with a suspended water height of less than 180 cm. However, with specific fURS/UAS(9.5Fr/12Fr) combos, the IRP exceeded the safe limit when using manual pumping. Gravity irrigation with a suspended water height of less than 180 cm is safe in this simulated clinical environment.

Assessment of Intrarenal Pressure through Dilatation State of the Renal Collecting System

INTRODUCTION

The aim of the study was to explore the relationship between the dilation states of the renal collecting system in flexible ureteroscopy (f-URS) view and intrarenal pressure (IRP).

METHODS

Fifteen porcine kidneys were randomly selected and numbered 1 through 15. Pressure transducers were inserted into the renal calyx via puncture and adjusted to a zero position. The distal end of the f-URS probe was placed within the renal pelvis. Perfusion rates of 50 mL/min, 80 mL/min, and 100 mL/min were utilized. We observed the relationship between the dilation state of the renal collecting system and changes in IRP. The state of complete dilation was defined as an unchanging spatial morphology of the renal collecting system as visualized during f-URS.

RESULTS

With irrigation rates of 50 mL/min, 80 mL/min, and 100 mL/min, IRP values at the moment of complete dilation of the renal collecting system ranged from 16 to 18 cm H2O, 16-19 cm H2O, and 16-19 cm H2O, respectively. Maximum IRPs ranged from 47 to 49 cm H2O, 82-85 cm H2O, and 97-100 cm H2O, respectively. Prior to complete dilation of the renal collecting system, IRP consistently remained below 20 cm H2O. However, following full dilation of the renal collecting system, IRP rose rapidly and rapidly surpassed 20 cm H2O. Despite sustained elevations in IRP following full dilation, no significant alterations in the renal collecting system dilated morphological were observed with f-URS.

CONCLUSIONS

In vitro experiments indicate that when the renal collecting system is not fully dilated, the IRP is consistently less than 20 cm H2O. Evaluation of IRP being within a safe range can be determined by assessing the dilation status of the renal collecting system.

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.

Factors affecting the intraoperative calculi excretion during flexible ureteroscopy lithotripsy: an in vitro analysis

OBJECTIVE

To explore the parameters influencing intraoperative calculi excretion (ICE) during flexible ureteroscopy lithotripsy (fURL) using in vitro simulation experiments.

METHODS

3D-printed human kidney models were used to simulate the elimination of gravel during fURL. The factors influencing the ICE during fURL were analyzed by comparing the effects of different degrees of hydronephrosis (mild, moderate, and severe), surgical positions (supine and lateral position), ratios of endoscope-sheath diameter (RESD) (0.625, 0.725, and 0.825), gravel sizes (0.50-1.00 mm, 0.25-0.50 mm, and 0.10-0.25 mm), and ureteral access sheaths (UASs) (traditional UAS and negative-pressure UAS) on ICE.

RESULTS

The impacts of various UAS, RESD, degree of hydronephrosis, surgical positions, and gravel sizes on ICE were all significant (p < 0.05). We found no evidence of multicollinearity for all the independent variables, and the linear regression equation fitted as ICE ( g / min ) = 0.102 + 0.083 ∗ UAS grade - 0.050 ∗ RESD grade - 0.048 ∗ hydronephrosis grade + 0.065 ∗ position grade - 0.027 ∗ gravel size grade (R2 = 0.569).

CONCLUSION

Employing negative-pressure UAS, smaller RESD, milder hydronephrosis, lateral position, and smaller gravel size contribute to improved ICE during fURL. Among them, the adoption of negative-pressure UAS had the most substantial effects.

Comparison of novel flexible and traditional ureteral access sheath in retrograde intrarenal surgery

OBJECTIVES

To compare the efficiency and safety of a novel flexible ureteral access sheath (f-UAS) and traditional ureteral access sheath (UAS) during retrograde intrarenal surgery (RIRS).

PATIENTS AND METHODS

Between January 2022 and September 2022, a total of 152 consecutive cases with renal stones underwent RIRS with the f-UAS. Their outcomes were compared with those of another 152 consecutive cases undergoing RIRS with traditional UAS using a 1:1 scenario matched-pair analysis, with matching parameters including age and stone size. The f-UAS is a novel UAS with a 10-cm-long tube at the tip that can follow the bends of flexible ureteroscope (f-URS).

RESULTS

Baseline characteristics were found to be similar between the two groups. The f-UAS group demonstrated significantly higher SFR (76.3% vs. 7.2%; P < 0.001) at 1 day postoperatively and a higher clearance rate of stone volume (98.11% vs. 91.78%; P < 0.001). The f-UAS group also had lower total complications rate (9.9% vs. 22.4%; P = 0.003), lower incidence of fever (5.9% vs 11.9%; P = 0.001), shorter operative times (56.5 min vs. 59.9 min; P = 0.047), and lower usage rate of baskets (17.1% vs. 100%; P < 0.001). There was no significant difference in SFR at 1 month postoperatively (P = 0.627) and in the length of postoperative hospital stay between the two groups (P = 0.225).

CONCLUSION

Compared to the traditional UAS during RIRS, the f-UAS showed several advantages, including higher SFR at 1 day postoperatively, shorter operative times, lower incidence of complications, and less use of basket.

How to measure intra-renal pressure during flexible URS: Historical background, technological innovations and future perspectives

INTRODUCTION

High intrarenal pressure (IRP) is a potential risk factor for infectious complications related to URS. Methods to lower IRP have been described. However, it is still not possible to assess live IRP values during URS. The objective of this study was to perform a systematic review of the literature regarding endoscopic methods to measure IRP during URS.

METHODS

A systematic search and review of Medline, PubMed and Scopus was conducted in accordance with the Preferred Reporting Items for Systematic Review and Meta Analysis (PRISMA) checklist and a narrative synthesis of the study results was performed.

RESULTS

A total of 19 articles were included in the review. Four non invasive (i.e. endoscopic) methods to measure IRP were reported: ureteral catheter, sensor wire, pressure sensor proximal to an irrigation system and a novel ureteral access sheath that integrates suction, irrigation, and IRP measurement.

CONCLUSIONS

We provide here a comprehensive overview of the reported clinical measuring systems of IRP during URS. The ideal system has not been developed yet, but urologists will be able to measure IRP during their daily practice soon. The implications of having this type of data during surgery remains unknown. Systems that could integrate irrigation, suction, IRP and temperature seems to be ideal.

Clinical application of novel integrated suctioning semi-rigid ureteroscopic lithotripsy

INTRODUCTION

Urinary calculi are frequently encountered in urology. Traditionally, the lack of a perfect water injection and drainage system means the observation field is affected during ureteroscopy. Here, we explored the effect and clinical value of a new integrated suctioning semi-rigid ureteroscopic lithotripsy (URSL) for treating ureteral calculi.

MATERIAL AND METHODS

A total of 180 patients were successfully enrolled in this study (60 in each group). Group A included patients who underwent a traditional semi-rigid URSL, group B included patients who underwent a suctioning semi-rigid URSL with a sheath being connected to a vacuum device, and group C included patients who underwent a new type of suctioning integrated rigid URSL with a novel designed ureteroscope.

RESULTS

In total, 164 cases of URSL were completed in one stage. Compared with group A, group C had a higher stone-clearance rate at 30 days postoperatively, shorter operation time, and fewer hospitalization days (p < .05); compared with group B, group C had a higher one-stage operation success rate, shorter operation time, and fewer hospitalization days (p < .05).

CONCLUSIONS

Comparatively, the new suctioning integrated semi-rigid URSL is advantageous for treating upper urinary calculi, considering the reduced operation time, length of hospital stay, and low invasiveness.

Omnidirectional (Flexible) Ureteral Access Sheath: Safety, Efficacy, and Initial Experience Report

Background: Recently a novel omnidirectional (OD) ureteral access sheath (UAS) has been developed. By retrospectively reviewing and comparing the flexible ureteroscopic lithotripsy (FURL) cases in our institution with either a conventional Cook UAS or an OD UAS in the past year, we shared our experience of the safety, efficacy, and relevant issues on the usage of OD UAS. Materials and Methods: The medical history and surgery details of 199 patients with kidney stones or ureterojunctional stones who underwent FURL in Xinhua Hospital, including 61 Cook UAS and 138 OD UAS, were reviewed and compared. The maximal deflection angle was measured by steering four different types of ureteroscopes to bend the OD UAS in different states. Result: The deflection angle of OD UAS was ∼110° to 130° free load, and 90° to 130° when loaded with different instruments. The stone burden and position were similar in two groups. Given a similar prestent ratio and operation time, the OD UAS group achieved a higher single-session stone-free rate (SFR) (63.9% vs 94.2%, p < 0.0001) at 1-month follow-up evaluated by a CT scan. Conclusion: OD UAS is a novel device with high safety and efficacy. The unique flexible design allows it to bend with the ureteroscope and enter renal calices and be set close to the stone. Combined with the suction port, OD UAS contributes greatly to dealing with large-burden kidney stones, shortens operation time, and improves single-session SFR.

Optimal placement of flexible ureteral access sheath in retrograde intrarenal surgery

This study aims to explore the optimal location of flexible ureteral access sheath (f-UAS) in retrograde intrarenal lithotripsy (RIRS). RIRS model was built by AutoCAD 2011 software, and imported COMSOL 5.6 software to computer simulation. An RIRS model was constructed in vitro to analyze the distribution pattern of stone fragments and compare the weight of stone fragments carried out by the irrigation fluid when the f-UAS is in different positions. Computer simulation showed that the highest flow of irrigation fluid was in the channel of flexible ureteroscopy (f-URS) and in the lumen of f-UAS. From the f-URS to the renal collection system and then to the f-UAS, the velocity of irrigation fluid changes gradually from high-flow to low-flow and then to high-flow. When the f-URS and the f-UAS are at the same level, the irrigation fluid is always at a state of high flow during the process from f-URS to f-UAS. When the f-URS and the f-UAS are at the same level, it can increase the local intrarenal pressure (IRP) at the front of f-URS. The stone fragments are mainly sediment in the low-flow region of irrigation fluid. More stone fragments could follow the irrigation fluid out of the body when the tip of f-URS and the tip of f-UAS are at the same level (P < 0.001). The f-UAS should be brought closer to the stone in RIRS. And more stone fragments can be taken out of the body by the effect of irrigation fluid.

Retrograde intra renal surgery and safety: pressure and temperature. A systematic review

PURPOSE OF REVIEW

Retrograde intra renal surgery (RIRS) with laser lithotripsy represents the gold-standard to treat renal stones up to 20 mm. Controlling intraoperative parameters such as intrarenal pressure (IRP) and temperature (IRT) is mandatory to avoid complications. This article reviews advances in IRP and IRT over the last 2 years.

RECENT FINDINGS

We conducted a PubMed/Embase search and reviewed publications that include temperature and pressure during RIRS. Thirty-four articles have been published which met the inclusion criteria. Regarding IRP, a consensus has emerged to control IRP during RIRS, in order to avoid (barotraumatic and septic) complications. Several monitoring devices are under evaluation but none of them are clinically approved for RIRS. Ureteral access sheath, low irrigation pressure and occupied working channel help to maintain a low IRP. Robotic systems and suction devices would improve IRP intraoperative management and monitoring. IRT determinants are the irrigation flow and laser settings. Low power settings(<20 W) with minimal irrigation flow (5-10 ml/min) are sufficient to maintain low IRT and allows continuous laser activation.

SUMMARY

Recent evidence suggests that IRP and IRT are closely related. IRP depends on inflow and outflow rates. Continuous monitoring would help to avoid surgical and infectious complications. IRT depends on the laser settings and the irrigation flow.

What is the appropriate gravel size during ureteroscopy lithotripsy? An in vitro evaluation

To propose the suitable diameter of calculus debris produced during flexible ureteroscopy lithotripsy (fURL). A glass tube was used to simulate the stone excretion process during Furl. Different stone diameters (0.50-1.00 mm, 0.25-0.50 mm, and 0.10-0.25 mm) with three sizes of flexible ureteroscopy (fURS) (7.5Fr, 8.7Fr, and 9.9Fr) and ureteral access sheath (UAS) (12/14Fr) with or without negative pressure suction were employed in the experiment. The intraoperative calculi excretion (ICE) was recorded according to the stones discharged from the gap between fURS and UAS. The ICE raised significantly in thinner fURS and UAS due to the smaller Ratio of Endoscope-Sheath Diameter (RESD). The gravel size ≤ 0.25 mm was conducive to drainage with traditional UAS, while using fURS with negative-pressure UAS could significantly improve ICE. The gravel size ≤ 0.5 mm was conducive to expulsion. We clarify that ICE during ureteroscopy relates to RESD and negative pressure suction. The proper size of the stone fragment is critical in ensuring the expulsion during fURL, ≤ 0.25 mm in traditional UAS and ≤ 0.50 mm in negative-pressure UAS, respectively.