Heather Beardsley

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.

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.

607 Magnetic Cautery Dissector for Single Site Laparoscopic Cholecystectomy in a Cadaver Model

The Magnetic Anchoring and Guidance System (MAGS) consists of an internal surgical device coupled across the abdominal wall and manipulated using an external handheld magnet. This video demonstrates a MAGS cautery dissector used in a cadaveric human cholecystectomy model. The gallbladder was retracted percutaneously and one laparoscopic instrument was used for assistance. The MAGS instrument was used to perform the entire dissection (18 minutes). The MAGS dissector provided excellent triangulation, obviated the need for additional laparoscopic instruments, minimized instrument conflicts, was compatible with human anatomical considerations, and greatly facilitated the single site approach.

Fluxless optical fiber attachment for hermetic MOEMS applications

Fluxless soldering is desirable for the hermetic packaging of micro-optoelectromechanical (MOEMS) systems, especially those used in harsh environments, or those that require very long shelf-life. An example of such a microsystem is a safe & arm (S&A) MEMS device that requires reliable operation over 20 to 30 years. For this application, degradation and out-gassing of the organic materials, such as those contained in fluxes and epoxies could result in the contamination and stiction of the moving microparts. In this paper we present simulation and experimental results of using a diode laser to attach and seal fiber optic feed-throughs to a kovar carrier package. In order to obtain reliable fluxless solder joints, certain environmental conditions namely, an inert and/or reducing gas environment needs to be present during the process. In addition, the solder and substrate surfaces must be sufficiently free of oxides and organic contaminants. Acceptable process parameters such as the laser power density, spot size, and duration, package geometry have been determined both experimentally and through simulation. It has been established that oxygen levels less than 0.04% (400 ppm) obtained inside a glove-box obtained using inert gas (100% N2 or 95%N2, 5% H2) is necessary to achieve adequate joints

Automated Assembly and Hermetic Packaging of MOEMS for Applications Requiring Extended Shelf-Lives

In this paper we describe two modular automated microassembly systems, along with a several packaging processes that have been integrated to produce reliable and cost-effective MOEMS devices. The automated and packaging systems consists of robotics such as pick and place, insertion and fastening, machine vision and controls, and processes such as die attach, solder reflow by laser, wire bonding and seam sealing. The target MOEMS devices are intended for applications requiring a minimum twenty year shelf-life.Copyright