Critical analysis of the miniaturized stone basket: effect on deflection and flow rate

In-vitro and in-vivo new evidence for Flexor® Vue™ deflecting endoscopic system use: optimization of the stone free rate (SFR) after flexible ureteroscopy and Ho:YAG laser lithotripsy

To test in-vitro and in-vivo the Flexor® Vue™ deflecting endoscopic system (FVDES) as a new technology able to improve the removal of residual intrarenal fragments.This is an observational prospective "proof of concept" study performed in patients with renal calculi treated with flexible ureteroscopy and Ho:YAG laser lithotripsy (f-URS) in Humanitas Research Hospital (Rozzano, Italy). We assessed feasibility, efficacy and safety of FVDES as an in-vivo tool for removing residual fragments after f-URS. The stone-free rate (SFR) at 30 days post-operatively was evaluated using CT. An in-vitro model was developed to evaluate the FVDES when used for this purpose.Eleven patients (M/F ratio: 7/4, mean age 63.5 ± 8.3) were treated. The stones were located in the lower calyces and the renal pelvis in 3 and 8 patients, respectively. Mean stone size was 18 ± 3.2 mm. The procedure with FVDES was feasible and effective in all the patients. Mean operative time was 82 ± 13.7 min and median hospitalization was of 1.5 days. The SFR after 90 days was 81% (9/11). We reported no relevant complications (Clavien-Dindo > 2); one patient had fever and was treated with antibiotics. The experimental in-vitro model demonstrated the efficacy of FVDES, allowing the removal of about 90% of fragments.Our study showed that FVDES is effective when used as a tool for retrieval of residual fragments at the end of f-URS. This technology could ensure a complete cleaning of the intrarenal collecting system and represent a safe alternative to basketing.

Ureteroscopy from the recent past to the near future

Stone surgery is one of oldest surgical practices undertaken by man. Hippocrates refused to let his followers "cut for the stone" and it was only in February 1980, when the first human trial of shock wave therapy on a renal stone was performed with success that a new era in minimally invasive treatment (surgery) for stones was opened up and this condemnation was finally resolved in the Hippocratic Oath. Endoscopy, using natural orifices, supported by anaesthesia, incremented by technology and with access to all points along the urinary tract, began by competing with ESWL, but is now the treatment of choice in most cases. As far as we know humans have always had stones. First, lithiasis was endemic bladder stones in children, now it is renal in general. Added to this a number of well-known risk factors, a rapid increase in obesity in the population, as well as bariatric surgery for its treatment, are causing an increase in the prevalence and recurrence of lithiasis everywhere. A short history of the advances made with the introduction and development of the ureteroscope, along with auxiliary devices, will show why this is the preferred technique at the moment for treating lithiasis in general and for treating stones in pregnant women, children and the obese in particular. Being a minimally invasive surgery, with a low morbidity and a very high efficiency and stonefree rate, has become established as a clear future technique for both adults and children. This development is not only due to technological advancements, but also to the routine use of the Holmium: YAG LASER for intracorporeal lithotripsy, capable of destroying any stone regardless of its composition or location, surpassing the ability of any other lithotripter. It is also due to the development of devices that allow access to the ureter and all parts of the kidney, as well as auxiliary aids to assist in the handling of stones during treatment. New LASERs, robotic control of the fdURS and digital imaging, as well as disposable devices, have had and, indeed, continue to have a unique impact on future development in this field. However, success will continue to depend on the careful choice of fURS, energy source and ancillary instruments obtained by the urologist during both real life and virtual training in human simulators.

Retrograde intrarenal surgery for renal stones - Part 1

The main aim in the treatment of renal stones is to clearance of the stones completely with the least morbidity. Parallel to the improvements in technology during recent years, new flexible ureterorenoscopes and effective lithotripters such as holmium laser have been developed, thus retrograde intrarenal surgery (RIRS) has become an efficient and safe option in the management of urinary system stone disease with a gradually increasing popularity. Therewithal, innovations in auxiliary equipment such as guide-wires, ureteral access sheath and stone baskets have made this procedure more effective. With this modality, nowadays, the vast majority of renal stones can be treated successfully without need of open surgery or percutaneous nephrolithotomy. RIRS can be used as a primary treatment in patients with renal stones smaller than 2 cm, in cases with prior unsuccessful shock wave lithotripsy (SWL), infundibular stenosis, renoureteral malformation, musculoskeletal deformity, bleeding diathesis as well as obese patients. The efficiency of this procedure has been also proved in pediatric patients. In the first part of this detailed review for RIRS, history, indications and contraindications, preoperative preparation, antibiotic prophylaxis, anesthesia, surgical technique related to flexible ureteroscopes and auxiliary equipment being used, postoperative care and complications of this operation are discussed with up-to-date literature.

Tipless Nitinol Stone Baskets: Comparison of Penetration Force, Radial Dilation Force, Opening Dynamics, and Deflection

OBJECTIVE

To evaluate 5 commercially available tipless nitinol baskets (2.2F) in 4 performance factors: penetration force, radial dilation force, opening dynamics, and deflection limitation.

MATERIALS AND METHODS

The 2.2F Coloplast Dormia No-Tip, 1.5F Sacred Heart Medical Halo, 2.2F Cook NCircle Nitinol Tipless Stone Extractor, 1.9F Bard SkyLite Tipless Nitinol Basket, and 1.9F Boston Scientific Zero Tip Nitinol Stone Retrieval Basket were tested for penetration force (safety metric), radial dilation force (functional metric for ureteral calculi), and opening or closing dynamics. Limitation of deflection (functional metric) was tested by measuring the difference in maximal upward and downward angle of deflection of a ureteroscope with and without a basket in place.

RESULTS

The Sacred Heart Medical Halo 1.5F basket had the highest mean force required to perforate the foil at 0.676N ± 0.117 (P < .0001). The Sacred Heart Medical Halo 1.5F basket also had the highest mean radial dilation force at 3.04 g ± 0.15 (P < .0001). The Cook NCircle Nitinol Tipless Stone Extractor 2.2F had the most linear pattern of opening, whereas the Coloplast Dormia No-Tip 2.2F and the Sacred Heart Medical Halo 1.5F exhibited exponential opening dynamics. The Cook NCircle Nitinol Tipless Stone Extractor 2.2F limited scope deflection the most with a decrease in 4° downward and 10° upward. The Sacred Heart Medical Halo 1.5F had the least influence on deflection with a decrease in 3° downward and 5° upward.

CONCLUSION

The penetration force, radial dilation force, opening dynamics, and resistance to deflection varied between 5 commonly available tipless nitinol stone baskets. A small diameter 1.5F basket is capable of providing optimal performance while sacrificing linear opening.

Clinical significance of residual fragments in 2015: impact, detection, and how to avoid them

PURPOSE

Residual fragments are common after stone treatment. Little is known about clinical outcomes relevant to the patient. This comprehensive review of the literature highlights the impact of residual fragments, modes of detection, and treatment strategies to avoid residual fragments in shock wave therapy, ureteroscopy, and percutaneous nephrolithotomy.

METHODS

A comprehensive review of current literature was performed using PubMed(®), MEDLINE(®), Embase™, Ovid(®), Google Scholar™, and the Cochrane Library. Publications relevant to the subject were retrieved and critically appraised.

RESULTS

Residual fragments after treatment for urinary stones have a significant impact on a patient's well-being and future course. (Ultra-) low-dose non-contrast computed tomography detects small residuals most reliably. In shock wave lithotripsy, adherence to basic principles helps to improve results. Various techniques and devices facilitate complete stone clearance in conventional and miniaturized percutaneous nephrolithotomy and (flexible) ureteroscopy. Promising new technologies in shock waves, lasers, and robotics (and potentially microrobotics) are on the horizon.

CONCLUSIONS

Residual fragments are relevant to patients. Contemporary treatment of urolithiasis should aim at complete stone clearance.

Advances in ureteroscopy

Ureteroscopy (URS) is a procedure which has been constantly evolving since the development of first generation devices 40 years ago. Progress towards smaller and more sophisticated equipment has been particularly rapid in the last decade. We review the significant steps that have been made toward improving outcomes and limiting morbidity with this procedure which is central to the management of urolithiasis and other upper urinary tract pathology.

Disposable devices for RIRS: where do we stand in 2013? What do we need in the future?

PURPOSE

Disposable devices for retrograde intrarenal surgery (RIRS) form a significant part of the urologist's armamentarium for the endoscopic management of urologic diseases. Herein, we provide an overview of the literature regarding the advances and controversies of these devices.

METHODS

A PubMed search was used to identify the literature discussing the subject of disposable devices for RIRS. Articles published between 2012 and 2013 were considered.

RESULTS

Ureteral access implements including access sheaths, wires, and dilators are an area of both improvement and controversy regarding their proper use. The safety, effectiveness, and limitations of lithotrites continue to be refined. Stone retrieval devices are undergoing persistent miniaturization, and their use may prove to be cost effective. The debate over perioperative stenting remains, while symptom management is explored. A cost-effective option for disposable flexible ureteroscopy shows promise.

CONCLUSIONS

While rapid advances in technology and knowledge continue, continual improvements are necessary. Disposable equipment needs persistent refinement and possible miniaturization. More efficient fragment retrieval devices are needed. Durability of laser fibers and safety within ureteroscopes needs to be improved. Reducing stent morbidity remains an ongoing challenge. Lastly, costs need to be reduced by the further development of disposable flexible ureteroscopes and in the recyclability of disposable devices to improve availability worldwide.

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.

1.2 French stone retrieval baskets further enhance irrigation flow in flexible ureterorenoscopy

Ureterorenoscopy (URS) has revolutionized upper urinary tract stone therapy. However, the size of the working channel and the stone baskets limit irrigation flow as well as vision. This study determined further improvements of irrigation flow, deflection capacities and impairments of breaking resistance in a new 1.2 French (F) ultra-miniaturized basket. Irrigation measurements were performed in semirigid URS (semiURS, working channel 5F) and in flexible URS (flexURS, 3.6F) in 0°, 90° and 270° deflection with 1.2F, 1.8F, 1.9F and 2.2F baskets and compared with empty channel. Breaking strength of 1.2F, 1.8F and 1.9F baskets were evaluated using a material testing machine. Tested baskets affected irrigation in semiURS and flexURS (p < 0.05). Mean ± SEM (standard error of the mean) for semiURS flow rates counted 197.1 ± 2.0, 140.9 ± 1.6, 111.1 ± 1.5, 98.0 ± 1.3 and 77.1 ± 0.9 ml/min for empty channel, 1.2F, 1.8F, 1.9F and 2.2F baskets (p < 0.05). Using unbent flexURS flow rates of 44.2 ± 0.4, 20.4 ± 0.2, 5.9 ± 0.1, 5.4 ± 0.1 and 1.5 ± 0.1 ml/min for empty channel, 1.2F, 1.8F, 1.9F and 2.2F baskets, were observed (p < 0.05). The 1.2F versus 2.2F basket showed a 13.6-fold increase in flexURS irrigation (p < 0.05), while only the 2.2F basket reduced deflection by 20.3 %. The breaking strength decreased with a reduced basket size (1.2F: 6.4 ± 0.46 vs. 1.8F: 16.8 ± 2.79 vs. 1.9F: 32.2 ± 2.74 N, p < 0.05). Ultra-miniaturized baskets of 1.2F ensured a sufficient irrigation flow as needed for high quality vision in URS stone management. However, miniaturization of the 1.2F basket resulted in a reduced breaking strength compared with larger sized devices which in turn may hamper stone removal by an increased vulnerability.