Use of an antiretropulsion device to prevent stone retropulsion significantly increases the efficiency of pneumatic lithotripsy: an in vitro study.
ABSTRACT To compare the efficiency of pneumatic lithotripsy with and without the Accordion antiretropulsion device (PercSys, Palo Alto, CA, USA).
The study comprised two in vitro experiments: in experiment 1, 10 trials were conducted using stone phantoms (6 x 6 x 10 mm), placed in a horizontal acrylic tube submerged in normal saline. Pneumatic lithotripsy was applied using a Swiss LithoClast (Boston Scientific Corporation, Natick, MA, USA). Each phantom was hit with repeated single firings of the LithoClast until it had travelled 20 cm (control group). The same experiment was then repeated with the Accordion antiretropulsion device positioned proximal to a new stone phantom. In experiment 2, stone phantoms (5 x 5 x 5 mm) were placed in a model ureter made of silicone and submerged in normal saline. Pneumatic lithotripsy was applied continuously on 10 stones for 20 s (200 strikes) without the Accordion device (control group) and on 10 stones with the Accordion device in place (experimental group). The distance of retropulsion was recorded. All stone phantoms were weighed before and after pneumatic lithotripsy.
In both experiments the Accordion group had a significantly greater percentage weight loss than the control group (experiment 1; 11% vs 3%; experiment 2, 53% vs 16%, both P < 0.001).
The Accordion device significantly increased the fragmentation efficiency in both in vitro models. Preventing retropulsion and increasing fragmentation efficiency has the potential to increase the success rate, decrease secondary procedures for migrated stones, and shorten operative times.
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ABSTRACT: Our objective was to evaluate the feasibility and initial performance of Backstop reverse thermosensitive polymer to prevent antegrade stone fragment migration during percutaneous nephrolithotomy. Backstop was used during 5 percutaneous nephrolithotomy procedures to prevent stone migration into the ureter. Backstop was placed into the upper ureter under direct vision with a flexible nephroscope or with fluoroscopic guidance. Ultrasonic lithotripsy was then performed. Each patient was evaluated for the following: stone-free rate (postoperative computed tomography), rate of antegrade fragment migration, need for subsequent procedures, and complication rate. The average stone burden was 806 mm(2). Backstop was successfully deployed in all cases. Average procedure length was 106 minutes. Three patients were rendered stone free, 1 patient retained 2 1-mm fragments in the kidney, and 1 patient retained multiple fragments in the kidney, distal ureter, and bladder, all of which were <3 mm. No patient required a secondary procedure, and there were no adverse events. Backstop appears to be feasible, safe, and easy to use. Backstop should be administered every 45 minutes for longer cases, and warm saline should be used during the case to prevent dissolution. A randomized controlled trial with a larger study population is needed to further evaluate these initial findings.Urology 12/2013; · 2.42 Impact Factor
Article: Antiretropulsion devices.[Show abstract] [Hide abstract]
ABSTRACT: Stone migration during the treatment of ureteral stones can prove frustrating and increases both healthcare cost and patient morbidity. Antiretropulsion devices have been engineered to prevent stone migration. Improvements in antiretropulsion devices allow for efficient prevention of stone migration during ureteroscopic lithotripsy with minimal adverse effects or complications. Multiple devices are now available each with advantages and disadvantages. New devices are currently engineered to prevent stone migration and maintain ureteral access. Antiretropulsion devices appear to be cost-effective to prevent stone migration during intracorporeal lithotripsy. Antiretropulsion devices have been safely and effectively used during ureteroscopic procedures. These tools increase stone-free rates, decrease morbidity and new studies have demonstrated their cost-effectiveness.Current opinion in urology 01/2014; · 2.50 Impact Factor
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ABSTRACT: Several studies of ureteroscopic treatment for ureteral stones have reported that most stone clearance failures can be attributed to stone fragment retropulsion. Stone retropulsion can result in increased operative time and cost-resulting from the need to change from the semi-rigid ureteroscope to a flexible instrument to chase migrated calculi-and additional procedures to treat residual migrated fragments are often required. The degree of migration depends mainly on the energy source used for lithotripsy; pneumatic and electrohydraulic lithotripters are associated with a greater degree of retropulsion than lasers. Different stone-trapping strategies and devices have been developed to minimize stone migration. Novel devices include the Lithovac(®) suction device, the Passport(™) balloon, the Stone Cone(™), the PercSys Accordion(®), the NTrap(®), and stone baskets such as the LithoCatch(™), the Parachute(™), and the Escape(®). Some authors have also reported on the use of lubricating jelly and BackStop(®) gel (a reverse thermosensitive polymeric plug); these devices are instilled proximal to the stone prior to the application of kinetic energy in order to prevent retrograde stone migration.Nature Reviews Urology 11/2012; · 4.79 Impact Factor