Comparison of automated irrigation systems using an in vitro ureteroscopy model

Intrarenal pressure and flow rate profile using LithoVue™ elite: impact of different irrigation systems and working channel instruments

PURPOSE

To report real-time IRP and FR while performing flexible ureteroscopy in porcine kidney model utilizing LithoVue™ Elite (Boston Scientific®) with different irrigation systems, including automated pumps.

METHODS

Using an ex-vivo model of porcine kidney, IRPs were measured with LithoVue Elite. Ureteroscopic settings (US) were tested with all permutations of irrigation methods (IM), working channel occupant (WCO), and ureteral access sheaths (UAS). IMs included: Single Action Pumping System (SAPS™, Boston Scientific), Thermedx FluidSmart™ (Stryker®), and ENDOMAT™ (Karl Storz®). Pumps were tested at 50, 100, and 150 mmHg. WCOs included a 1.9Fr zero-tip basket, 200 µm, and 365 µm laser fibers. UASs utilized 11/13Fr and 12/14Fr 36 cm.

RESULTS

84 different US were tested (252 experiments). ENDOMAT had higher IRP but the same FR as Thermedx at the same US for 50 and 100 mmHg (p < 0.01). SAPS had higher IRP and FR than pumps in all US studies (p < 0.01). There was positive correlation between pressure set by the pump and both IRP and FR (rho > 0.9). As the diameter of the WCO increased, lower IRP and FR were observed with the pumps (p < 0.01). With SAPS, IRP was similar regardless of WCO, but FR was decreased with the increased diameter of WCO (p = 0.81 and p < 0.01, respectively). There was significantly higher IRP when using 11/13Fr UAS than 12/14Fr (p < 0.01).

CONCLUSION

IRP was higher with SAPS than automated pumps. ENDOMAT showed higher IRP than Thermedx when under 150 mmHg. IRP and FR increase with higher pump pressure and decrease with larger diameter WCO. Likewise, a larger UAS significantly reduced IRP.

Location of ureteral access sheath in the ureter. Does it affect the fluid flow in different calyces?

Introduction

The aim of this study was to evaluate outflow variation in different locations of the pyelocaliceal system with the use of different ureteral access sheath (UAS) sizes and different UAS positioning.

Material and methods

The experimental setup included an anaesthetised porcine model, a 7.5-Fr ureteroscope with a 200-μm laser fibre inserted in the working channel, a hand-held pumping irrigating system, and UAS of different sizes, namely: 9.5/11.5 Fr, 12/14 Fr, and 14/16 Fr. Each UAS was placed just below the ureteropelvic junction (UPJ) or in the mid-ureter. The ureteroscope was placed in the renal pelvis, upper and lower calyces, and outflow measurements were obtained with 3-second interval pumping for one minute in every experimental setup.

Results

The UAS positioning in the mid-ureter was associated with significantly higher outflow rates in the lower calyx (p = 0.041). While the UAS was below the UPJ, we observed a trend of lower outflow rate in the lower calyx, which was completely inverted when the UAS was in the mid-ureter. Increasing the UAS size from 9.5/11.5 Fr to 12/14 Fr led to a significant increase in outflow in the renal pelvis and upper calyx (p = 0.007), but not in the lower calyx. A further increase to 14/16 Fr did not produce increased flow.

Conclusions

Different locations of the pyelocaliceal system have different fluid mechanics during fURS. In the renal pelvis and upper calyx increasing the diameter of the UAS improved the outflow, whereas in the lower calyx the position of the UAS seems to be the most relevant factor. These variables should be considered when performing fURS, especially with high-power laser lithotripsy.

Under pressure: irrigation practice patterns during flexible ureteroscopy

Introduction

Irrigation parameters during flexible ureteroscopy (fURS) may impact patient outcomes, yet there are limited data on current practice patterns of irrigation methods and parameter selection. We assessed the common irrigation methods, pressure settings, and situations that present the most problems with irrigation among worldwide endourologists.

Methods

A questionnaire on fURS practice patterns was sent to Endourology Society members in January 2021. Responses were collected through QualtricsXM over a 1-month period. The study was reported according to the Checklist for Reporting Results of Internet E-Surveys (CHERRIES). Surgeons were from North America (the United States and Canada), Latin America, Europe, Asia, Africa, and Oceania.

Results

Questionnaires were answered by 208 surgeons (response rate 14%). North American surgeons accounted for 36% of respondents; 29% Europe, 18% Asia, and 14% Latin America. In North America, the most common irrigation method was the pressurized saline bag using a manual inflatable cuff (55%). Saline bag (gravity) with a bulb or syringe injection system was the most common method in Europe (45%). Automated systems were the most common method in Asia (30%). For pressures used during fURS, the majority of respondents used 75-150 mmHg. The clinical scenario which had the greatest issue with adequate irrigation was during biopsy of urothelial tumor.

Conclusion

There is variation in irrigation practices and parameter selection during fURS. North American surgeons primarily used a pressurized saline bag, in contrast to European surgeons who preferred a gravity bag with a bulb/syringe system. Overall, automated irrigation systems were not commonly used.

Ergonomics and Surgeon Comfort During Flexible Ureteroscopy

The technological advancements of flexible ureteroscopy (FURS) and its accessories have resulted in broadening its indications to include the management of complex renal stones, with long operative time. The surgeon's understanding about the ergonomics of the ureteroscopes and their cognizance of the operation theatre layout helps to improve their performance, including the surgical outcomes. This paper will describe the ergonomics that are involved in conducting FURS which in turn will aid in developing a more conducive surgical environment for the surgeon during the procedure, based on scientific literature review and expert opinions in high-volume centres. Proper surgeon position, well-arranged operation theatre layout, monitor and pedal position, anaesthesia type, and surgical team are important factors to decrease musculoskeletal strains for surgeons and increase work efficiency. Different types of flexible ureteroscope have different characters and knowing these special characters leads to better ergonomics during surgery. Robotic-assisted FURS have shown good safety and ergonomics in clinical application.

Evaluation of a Novel Female Gender Flexible Ureteroscope: Comparison of Flow and Deflection to a Standard Flexible Ureteroscope

Introduction: The advent of single-use disposable flexible ureteroscopes allows for rapid prototyping of novel endoscopes. In this regard, we sought to develop a female-specific ureteroscope, with a shorter working length, to account for the female anatomy. We hypothesized that the shorter, female-specific single-use flexible ureteroscope would engender higher irrigation flow at a given pressure than that of the standard-length ureteroscope. Methods: An in vitro analysis of a standard 65 cm Dornier Axis™ ureteroscope and a shorter, 45 cm female-specific Dornier Axis ureteroscope was performed. All other aspects of the endoscopes were identical. Each ureteroscope was oriented vertically and connected to a Thermedx^® irrigation system to provide uniform pressurized flow. The average flow rate was computed over five, 2-minute periods at pressure settings of 50, 100, 150, and 200 mm Hg. Data were collected with the working channel unoccupied, after placement of a 200 μm (0.6F) holmium laser fiber and after passage of a 1.7F stone basket. The procedure was then repeated with the endoscopes at maximum deflection. Results: The female gender ureteroscope had significantly higher irrigation flow rates than the standard-length ureteroscope under all conditions by an average of 11% (p < 0.02). The highest average percent increase, 17% (p < 0.001), was seen with the 1.7F NGage^® basket in the working channel with the endoscope straight. The maximum angle of deflection was not significantly different between the female gender and standard ureteroscopes with an open working channel (314° vs 315°, p = 0.86), with the 1.7F NGage basket in place (314° vs 315°, p = 0.15), and with the 200 μm holmium laser in place (316° vs 309°, p = 0.09). Conclusions: A 45 cm female gender ureteroscope allows for a higher irrigation flow rate than the standard-length ureteroscope under all test conditions. There is no added benefit with regard to deflection capabilities.