Development and Evaluation of a Novel Endoscopic Sack to Facilitate Tissue Prostate Adenoma Morcellation.

INTRODUCTION: Morcellation of the adenoma after laser enucleation of the prostate (LEP) is both time-consuming and prone to complications. We have designed a novel polyethylene sack (ProSac) to improve the morcellation process following LEP. Both silicone and cadaver models were utilized to evaluate the safety and efficacy of ProSac. METHODS: The inanimate model used tissue-mimicking silicone to accurately approximate bladder volume and compliance. The second model was developed using a fresh cadaver. Heat-fixed chicken breast was used to mimic enucleated prostatic adenoma. Morcellation of the simulated adenoma tissue was tested in both models with and without the ProSac. Morcellated tissue was removed from the filter, desiccated, and weighed after each run to establish morcellation efficiency. Visual inspection was used to evaluate for mucosal injury or bladder perforation. A hydromanometer was placed in the cadaveric bladder to measure bladder pressure. RESULTS: The device was able to capture up to 30 g of tissue with good closure while maintaining good distention and visualization during morcellation. In the silicone model, morcellation efficiency with the device was 4.6 g/minute, while efficiency without the device was 2.6 g/minute (p = 0.03). In the cadaveric model, mean entrapment time was 22 ± 11 seconds. Morcellation efficiency with the device was 2.1 g/minute when excluding entrapment time and 1.9 g/minute including entrapment time. Without the ProSac, morcellation efficiency was 1.2 g/minute (p = 0.05). In both models, multiple mucosal injuries occurred without the device, while none occurred with the device. Bladder pressure was similar between study arms. CONCLUSIONS: The ProSac is a novel device that can provide additional safety during adenoma morcellation. It may also achieve clinically and statistically significant improvement in morcellation efficiency without increasing bladder pressure.

A Novel Device to Prevent Stone Fragment Migration During Percutaneous Lithotripsy: Results from an In Vitro Kidney Model.

PURPOSE: We developed a polyethylene sack (the PercSac) that fits over the shaft of a rigid nephroscope and is deployed into the collecting system to capture a stone and contain fragments during percutaneous nephrolithotomy (PCNL). We previously reported our results using the PercSac in a percutaneous cystolithopaxy model. In this study, we compare the efficiency of stone fragmentation with and without the PercSac in an anatomically correct in vitro PCNL model. MATERIALS AND METHODS: The PCNL model consisted of a human collecting system model created on a 3D printer. Ten BegoStones made in spherical molds of 2.0 cm diameter, matched for weight, were fragmented in the model using a 24F rigid nephroscope and an ultrasonic lithotripter, including five with and five without the PercSac. The total times for stone fragmentation and complete stone clearance, gross assessment of the stone-free status, and need for flexible nephroscopy to achieve a stone-free state were recorded. RESULTS: The median time for stone fragmentation was significantly shorter in the PercSac group compared with the control group (217 seconds [IQR = 169-255] vs 340 seconds [IQR = 310-356], [p = 0.028]). Likewise, the total time for complete stone clearance from the kidney was significantly shorter for the PercSac group (293 seconds [IQR = 244-347] vs 376 seconds [IQR = 375-480], [p = 0.047]). In one trial with the PercSac, residual dust remained in the kidney, while in all five trials without the PercSac small residual fragments remained. All trials without the PercSac required flexible nephroscopy with basket extraction to become stone free, while none of the trials with the PercSac required flexible nephroscopy for stone clearance. CONCLUSIONS: Ultrasonic lithotripsy using the novel PercSac stone entrapment device is more efficient and efficacious than traditional ultrasonic lithotripsy in an in vitro PCNL model. The advantage may be even more pronounced during clinical PCNL where residual fragments migrate into difficult-to-access calices. Further in vivo testing is underway.

A novel device to prevent stone fragment migration during percutaneous lithotripsy.

PURPOSE: We developed a novel device to capture stones in vivo in an enclosed bag (PercSac) to prevent dispersion of stone fragments during percutaneous nephrolithotomy (PCNL) or cystolitholapaxy. We report on our initial feasibility trials of the PercSac device. MATERIALS AND METHODS: PercSac consists of a specially designed polyethylene bag that is fitted over the shaft of a rigid nephroscope. The bag is used to first entrap the target stone, then tighten around it to allow fragmentation within the bag. Matched pairs of 10 canine bladder stones (2.5 cm maximum diameter) were fragmented in a human bladder model using the CyberWand (Olympus America, Inc.), and the procedure was assessed for markers of efficiency and effectiveness. RESULTS: Median time to entrap the stone within the PercSac was 67 seconds (range 51-185 sec). Median time for stone fragmentation was significantly shorter with the PercSac than without (182.0 sec [range 108-221] vs 296.5 sec [range 226-398], P=0.004). Overall, however, there was no significant difference in the total time to entrap and fragment the stones between the two groups. A stone-free state was not achieved for any trial without the PercSac, while 9 of 10 trials with the PercSac resulted in a stone-free state. CONCLUSIONS: Use of the PercSac in conjunction with stone fragmentation has the potential to reduce the occurrence of residual fragments after PCNL or cystolitholapaxy. Further in vitro testing in a kidney model is planned.

In vitro comparison of prototype magnetic tool with conventional nitinol basket for ureteroscopic retrieval of stone fragments rendered paramagnetic with iron oxide microparticles.

PURPOSE: We developed a prototype magnetic tool for ureteroscopic extraction of magnetized stone particles. We compared its efficiency for retrieving magnetized calcium oxalate monohydrate stone particles with that of a conventional nitinol basket from the pelvi-collecting system of a bench top ureteroscopic simulator. MATERIALS AND METHODS: Iron oxide microparticles were successfully bound to 1 to 1.5, 1.5 to 2 and 2 to 2.5 mm human calcium oxalate monohydrate stones. Several coated fragments of each size were implanted in the collecting system of a bench top ureteroscopic simulator. Five-minute timed stone extraction trials were performed for each fragment size using a back loaded 8Fr magnetic tool mounted on a 0.038-inch guidewire or a conventional basket. The median number of fragments retrieved per timed trial was compared for the magnetic tool vs the basket using the Mann-Whitney U test. RESULTS: For 1 to 1.5 mm fragments the median number retrieved within 5 minutes was significantly higher for the prototype magnetic tool than for the nitinol basket (9.5 vs 3.5, p = 0.03). For 1.5 to 2 mm fragments the magnetic tool was more efficient but the difference in the number of fragments retrieved was not statistically significant (9.5 vs 4.5, p = 0.19). For 2 to 2.5 mm fragments there was no difference between the instruments in the number retrieved (6 per group, p = 1.0). CONCLUSIONS: The prototype magnetic tool improved the efficiency of retrieving stone particles rendered paramagnetic that were less than 2 mm but showed no advantage for larger fragments. This system has the potential to decrease the number of small retained fragments after ureteroscopic lithotripsy.

Tissue compression analysis for magnetically anchored cautery dissector during single-site laparoscopic cholecystectomy.

INTRODUCTION: The purpose of this study was to evaluate the histological effects of dynamic abdominal wall compression using the magnetic anchoring and guidance system (MAGS) platform. METHODS: Cholecystectomy was performed in two nonsurvival and two survival pigs using a single-site laparoscopic (SSL) approach. A deployable MAGS cautery dissector was used to perform the entire dissection in conjunction with a laparoscope and other instruments. The abdominal wall areas corresponding to the region occupied by the MAGS platform were examined grossly and microscopically for signs of tissue damage. Gallbladder dissection time was 36 min with no complications. Compressed abdominal wall thickness was 1.4 cm. RESULTS: In all four animals, a very mild skin erythema was noted immediately postprocedure but was nonvisible within 20 min. Mild peritoneal blanching was noted in two animals, and one animal exhibited a 5-mm area of petechiae. Necropsy demonstrated no adhesions. Light microscopy documented no evidence of tissue injury for all specimens. DISCUSSION: This study demonstrated that the use of the MAGS cautery dissector for a SSL cholecystectomy was advantageous in providing triangulation and did not result in any significant gross or microscopic tissue damage despite the thin abdominal wall of the porcine model.

Magnetic anchoring and guidance system instrumentation for laparo-endoscopic single-site surgery/natural orifice transluminal endoscopic surgery: lack of histologic damage after prolonged magnetic coupling across the abdominal wall.

OBJECTIVES: To study the potential pathologic effect of prolonged compression of abdominal wall between the components. Magnetic Anchoring and Guidance System (MAGS) instruments ameliorate some of the challenges in triangulation created by laparo-endoscopic single-site and natural orifice translumenal endoscopic surgery. They consist of an intracorporeal magnetic device coupled to an external hand-held magnet used to anchor and "steer" it around the peritoneal cavity. METHODS: Three pigs (45.5-48.6 kg) underwent laparoscopic placement of magnetic devices in 4 quadrants, with the devices left in place for 2 or 4 hours. Full-thickness abdominal wall sections (mean 2.1 cm thick) where each MAGS platform was placed plus a control were harvested at 0, 2, or 14 days after surgery. Histologic assessment was then performed. RESULTS: Beyond mild blanching of the peritoneal surface with a few petechiae immediately after internal component removal, no gross tissue damage was seen. These changes were undetectable by 48 hours and no intra-abdominal adhesions were identified at necropsy. NADH stain for tissue viability in the 4 nonsurvival specimens showed no tissue damage. Hematoxylin and eosin stain showed no necrosis of either superficial or deep muscle, skin, or subcutaneous fat tissue in all 12 specimens when compared with the control. CONCLUSIONS: MAGS instruments do not appear to cause tissue damage or adverse clinical outcomes when coupled across thin porcine abdominal walls for up to 4 hours. Because the distance across the abdominal wall is generally greater in adult human beings, these findings support the further clinical development of magnetic instruments to be used in human patients.