The new Olympus digital flexible ureteroscope (URF-V): Initial experience

Illumination matters part IV: blackout and whiteout in flexible ureteroscopy - first report on a phenomenon observed by PEARLS

PURPOSE

To date, no study has evaluated effects of varying brightness settings on image quality from flexible ureteroscopes submerged in saline. The aim was to evaluate blackout and whiteout occurrences in an in-vitro kidney calyx model.

MATERIAL AND METHODS

We evaluated a series of contemporary flexible ureteroscopes including the Storz Flex-Xc and Flex-X2s, Olympus V3 and P7, Pusen 7.5F and 9.2F, as well as OTU WiScope using a 3D-printed enclosed pink in-vitro kidney calyx model submerged in saline. Endoscopic images were captured with ureteroscope tip placed at 5 mm,10 mm and 20 mm distances. The complete range of brightness settings and video capture modes were evaluated for each scope. Distribution of brightness on a grayscale histogram of images was analyzed (scale range 0 to 255). Blackout and whiteout were defined as median histogram ranges from 0 to 35 and 220 to 255, respectively (monitor image too dark or too bright for the human eye, respectively).

RESULTS

Blackout occurred with the P7, Pusen 7.5F, 9.2F and WiScope at all distances, and V3 at 20 mm - with lowest brightness settings. Whiteout occurred with Flex-X2s, V3 and P7 at 5 mm and 10 mm, as well as with V3 and P7 at 20 mm - mostly with highest brightness settings. The Flex-Xc had neither blackout nor whiteout at all settings and distances.

CONCLUSION

Blackout or whiteout of images is an undesirable property that was found for several scopes, possibly impacting diagnostic and therapeutic purposes during ureteroscopy. These observations form a guide to impact a urologist's choice of instruments and settings.

Design and kinematics of a tube-shaped multidirectional bending robotic device using slackened SMA wires for transurethral ureterolithotripsy

PURPOSE

The complex and elaborate structure of the urinary system presents surgeons with difficulty in using a ureteroscope with a fixed optical fiber to reach the targeted calculus. To address this challenge, a robotic device is required to control the direction of laser irradiation position independently in ureteroscopes.

METHOD

A continuum robotic device was designed and fabricated. The device is constructed with three slackened shape memory alloy (SMA) wires to control the laser irradiation position of the optical fiber combined with the view of the camera on the tip of the ureteroscope. Kinematics analysis and experimental evaluation reveal the capability of the device.

RESULTS

The structure of the device is the same as a single-joint continuum robot. This device is unique because of the tiny diameter of 1.1 mm which can be used inside the ureteroscope through a Ø1.2 mm inner channel into the kidney for transurethral ureterolithotripsy. Kinematic analysis revealed the relationship among space coordinates, angles of bending, and direction and SMA wires length. The maximum bending angle was around 25° when the current value was 350 mA on a single SMA wire. The device could achieve multi-directional bending by allocating the values of current on SMA wires, separately.

CONCLUSION

This device offers a major advancement in small size and dexterity in medical robotics. Combined with a proper control system, this device could simplify the operation and improve the efficiency of the transurethral ureterolithotripsy.

How to evaluate a flexible ureterorenoscope? Systematic mapping of existing evaluation methods

Objectives

The objective of this study was to identify, map and review scope‐related and user‐related parameters used to evaluate the quality of flexible ureterorenoscopes. Thereby identifying key items and variability in grading systems.

Methods

A literature search of four databases (MEDLINE [Ovid], EMBASE [Ovid], Web of Science, Google scholar and the Cochrane Library) was performed according to the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses guidelines encompassing articles published up to August 2020. A total of 2386 articles were screened.

Results

A total of 48 articles were included in this systematic scoping review. All studies had a prospective design. Five key items in the assessment of flexible ureterorenoscopy were distinguished: ‘Manoeuvrability’ (87.5%), ‘Optics’ (64.6%), ‘Irrigation’ (56.3%), ‘Handling’ (39.6%) and ‘Durability’ (35.4%). After regrouping, every key item could be divided into specific subcategories. However, the quality assessment showed a wide variation in denomination, method of measurement, circumstances of measurement, tools used during measurements, number of measurements performed, number of observers, and units of outcomes.

Conclusion

The research field regarding quality assessment of ureterorenoscopes is heterogeneous. In this systematic scoping review we identified five key parameters: Manoeuvrability, Optics, Irrigation, Handling and Durability, used to grade flexible ureterorenoscopes. However, within these categories we found a wide variety in terms of method of measurements. A standardised, uniform grading tool is required to assess and compare the quality of flexible ureterorenoscopes in the future.

Comparative investigation of reusable and single-use flexible endoscopes for urological interventions

In order to evaluate the technical adaptability of a type of disposable endoscope compared to reusable flexible endoscopes, in vitro and in vivo studies were conducted. A disposable digital ureteroscope ("chip on tip") and two reusable endoscopes were investigated with respect to spatial resolution, geometric distortion in air and water the maximum. Additionally, the clinical performance of the disposable device was tested during clinical procedures (n = 20). The disposable endoscope showed an optical resolution of 6.72 lines/mm at 10 mm distance, similar to the other devices. In comparison, the disposable endoscope showed a barrel-shaped image distortion in air of -24.2%, which is in the middle range, but was best under water (-8.6%). The bendability of 297° (275 µm fiber) and 316° (empty channel, 1.5 F basket) and the maximum irrigation (1 m: 58.1 ml/min, 2 m: 91.9 ml/min) were convincing. Clinically the maneuverability was very good in (13/20), good or satisfactory in (7/20). Visibility was evaluated as very good in (11/20), just in (1/20) either satisfactory or sufficient. The consistency of visibility was not affected in (19/20). In all cases there were no adverse events. The technical examination and clinical application of the disposable endoscope are of equal quality compared to reusable devices. Disposable endoscopes can be an alternative to reusable devices, but economic aspects such as reduction of repair costs, sterilization effort and additional waste must be taken into account.

Digital ureteroscopes: technology update

The field of ureteroscopy has undergone a continual evolution since the first ureteroscopes were introduced. Over the past 10 years, we have entered into the digital era of ureteroscopy with both semirigid and flexible options becoming available. The following review looks at the benefits and drawbacks of digital flexible ureteroscopes as well as the current commercially available options.

First clinical evaluation of a new single-use flexible ureteroscope (LithoVue™): a European prospective multicentric feasibility study

INTRODUCTION

We evaluated a new digital single-use flexible ureteroscope, LithoVue™ with respect to deflection, image quality and maneuverability.

METHODS

A prospective cohort study was conducted in eight tertiary reference centers in Europe in December 2015 and January 2016. All consecutive patients included underwent flexible ureteroscopy and were 18 years or older. Deflection and image quality pre- and post-use and maneuverability were rated with a Likert scale.

RESULTS

A total of 40 procedures were performed (five per institution). The indication for FURS was treatment of renal stones in 92.5 % of the cases. Before LithoVue™ usage, the median measured upward and downward deflections were both 270°. Image quality was rated as "very good" in 65 % of cases and "good" in 30 %. Maneuverability was "very good" in 77.5 % and "good" in 17.5 %. At the final evaluation, median upward and downward deflections were both 270°. Image quality was still "very good" in 65 % of cases and "good" in 30 % with no significant difference compared with preoperative data (p = 1). Maneuverability was "very good" in 72.5 % and "good" in 17.5 %, with no significant difference compared with preoperative data (p = 0.92). Two LithoVue™ broke during surgery (5 %): one occurring in extreme deflection with acute infundibulopelvic angle and spontaneous loss of vision for the second one.

CONCLUSION

The LithoVue™ displayed good image quality, active deflection and maneuverability. Further evaluation of surgical outcomes and cost analysis will help to present the best utility of this single-use FURS in current practice.

Improved durability of flex-Xc digital flexible ureteroscope: how long can you expect it to last?

OBJECTIVE

To retrospectively analyze a significant number of flexible ureterorenoscopic procedures performed with the Storz Flex-Xc model to evaluate its durability.

MATERIALS AND METHODS

Between May 2012 and May 2013, all the flexible ureteroscopic procedures performed with 3 Storz Flex-Xc flexible ureteroscopes were analyzed. Relocation of the lower pole stones was performed in all cases when possible. In the second and third series, the access sheath was retracted together with the flexible ureteroscope, thus preventing the damages, which its distal part may inflict on the flexed endoscope.

RESULTS

A total of 406 procedures were performed on 372 patients: first endoscope used on 96 procedures (90 patients), second one on 151 procedures (139 patients), and third one on 159 procedures (143 patients). Ureteral access sheath was used in 71.4% of the cases. The first endoscope was used for 67.1 hours, the second for 107.7 hours, and the third one for 107.2 hours. Major repairs were needed after significant damages of the outer coating (first endoscope) and severe deterioration of the deflecting mechanism (second and third endoscopes).

CONCLUSION

The digital Storz Flex-Xc seems to be a durable model of flexible ureteroscope. The use of ureteral access sheath and avoidance of overstressing the deflection mechanism by relocating lower pole stones seem to offer substantial advantages in prolonging the lifespan of these expensive instruments.

Outcomes of flexible ureterorenoscopy and laser fragmentation for renal stones: comparison between digital and conventional ureteroscope

OBJECTIVE

To compare the outcomes of flexible ureterorenoscopy and lasertripsy (FURS) using digital and conventional FURS for kidney stones.

METHODS

From September 2007 to April 2011, 118 patients underwent FURS (by the same surgeon). The outcomes were compared between equal numbers of procedures (59 each) using a conventional flexible ureterorenoscope (C-FURS; Olympus URF-P5) and a digital flexible ureterorenoscope (D-FURS; Olympus URF-V). Although the deflection, working channel, and field view are similar in both, the initial and terminal diameter is 8.4F and 9.9F and 6.9F and 8.4F for the D-FURS and C-FURS, respectively. The mean stone fragmentation time was calculated by the size per operative time. The preoperative, operative, and postoperative data were retrospectively analyzed and compared.

RESULTS

The patient demographics were comparable. The mean stone size was 12.8 and 12 mm in the C-FURS and D-FURS groups, respectively. The initial assessment of the entire pyelocaliceal system was possible in 58 of 59 cases (98%) in the C-FURS group and 56 of 59 cases (94%) in the D-FURS group. The mean operative time was significantly longer in the C-FURS group (53.8 ± 15.2 minutes vs 44.5 ± 14.9 minutes). The overall stone-free rate 1 month after the procedure was 86% in the C-FURS group and 88% in the D-FURS group.

CONCLUSION

Although on comparison, the D-FURS had slightly limited maneuverability, comparable success rates can be achieved with both conventional and digital ureteroscopes. D-FURSs significantly reduced the operative time compared with C-FURSs.

A new era: performance and limitations of the latest models of flexible ureteroscopes

OBJECTIVE

To comparatively study 3 of the latest models of flexible ureteroscopes using both subjective and objective parameters.

MATERIALS AND METHODS

Three models of flexible ureteroscopes (Karl Storz Flex-Xc, Olympus URF-Vo, and Wolf Cobra) were evaluated during 90 procedures. For each model, 20 procedures were therapeutic for pyelocaliceal lithiasis and 10 were diagnostic. The maneuverability and visibility were scored and compared, and the irrigation flow and maximal deflection were measured in an ex vivo setting, with an empty working channel and with accessory instruments in place. Instrument durability was also reviewed.

RESULTS

All models demonstrated good maneuverability, with a slight advantage for the Flex-Xc. During the diagnostic procedures, failure to access the entire pyelocaliceal system occurred in 2 cases with the URF-Vo, both because of a thin caliceal infundibulum, and in 1 case with the Cobra, because of complex caliceal architecture. Regarding visibility, although the performance of the digital models was relatively similar, the fiberoptic Cobra achieved a lower score. Loss of deflection and irrigation when using the various ancillary instruments was similar for all 3 endoscopes, but the Cobra offered supplementary flow through a secondary channel. The mean deflection loss was 5% for the URF-Vo, 9% for the Flex-Xc, and 10% for the Cobra. The visual quality of the 2 digital models remained unchanged during the study; however, in the fiberoptic ureteroscope, 58 optic fibers were broken.

CONCLUSION

The latest models of flexible ureteroscopes have proved to be effective instruments for upper urinary tract endoscopic interventions. There is still room for improvement, already made possible by the technological advances.

Improving the durability of digital flexible ureteroscopes

OBJECTIVE

To present the damage to digital flexible ureteroscopes after 1 year of use in a tertiary stone center and our strategy to reduce the damage.

MATERIALS AND METHODS

Data regarding all procedures performed with 3 new digital flexible ureteroscopes (Olympus URF-V) were collected. We examined the conditions under which the damage occurred and retrieved the manufacturer's repair reports. Two study groups were created. Group 1 included all the procedures performed before the introduction of a set of guidelines for safe use of the digital flexible ureteroscopes and a stepwise credentialing process for new surgeons. Group 2 included all the procedures performed thereafter.

RESULTS

A total of 141 procedures were performed in 122 patients. Five events of damage occurred in the first study group and were related to working in maximum deflection. In the second group only 3 events occurred. The damage affected the angulation system, working channel, or body shaft. No damage occurred to the imaging system of any ureteroscope. The changes that were made after the first 5 months of use resulted in a significant prolongation of the number of uses before damage occurred for every ureteroscope (10.6 vs 21.6 uses before damage, P = .035).

CONCLUSION

The optical system of the new digital ureteroscopes is very durable; however, the overall longevity depends on the correct handling of their use. By following the proposed guidelines for safe use and with monitored training of new users, these instruments can have a significantly longer lifespan.

Advances in ureteroscopy

Recent innovations in imaging equipment and novel instrumentation have helped ureteroscopy evolve from a diagnostic to a therapeutic tool. In this review, the authors highlight several of the most recent advances in ureteroscopy that have helped allow unprecedented access, visualization, and treatment of upper urinary tract pathologic conditions.