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Waves in thermoelastic solids and saturated porous media
Published in Benjamin Loret, Fernando M. F. Simões, Biomechanical Aspects of Soft Tissues, 2017
Benjamin Loret, Fernando M. F. Simões
On another side, extracorporeal shock wave lithotripsy and intracorporeal ultrasound lithotripsy using lower frequencies but higher intensities than for medical diagnosis are routinely used to trigger the comminution of kidney stones. Further potential applications of shock waves, such as in vitro and in vivo damaging of tumor cells and healing of muskulo-skeletal disorders, have been suggested. The high amplitude waves generate positive and negative pressures that are thought to induce cavitation. The mechanisms through which cavitation acts to succeed in the healing process are not yet understood. Neo-vascularization induced by micro-injuries and enhancement of cellular reactions are potential candidates.
Urology
Published in David A Lisle, Imaging for Students, 2012
Shock wave lithotripsy uses highly focused sound waves to fragment renal or ureteric stones. Where the shock waves are generated outside the body, the process is referred to as extracorporeal shock wave lithotripsy. Intracorporeal shock wave lithotripsy refers to shock waves generated inside the body through a ureteroscope. Shock wave lithotripsy is the technique of choice for the management of most renal stones.
Potential strategies to prevent encrustations on urinary stents and catheters – thinking outside the box: a European network of multidisciplinary research to improve urinary stents (ENIUS) initiative
Published in Expert Review of Medical Devices, 2021
Ali Abou-Hassan, Alexandre Barros, Noor Buchholz, Dario Carugo, Francesco Clavica, Petra de Graaf, Julia de La Cruz, Wolfgang Kram, Filipe Mergulhao, Rui L Reis, Ilya Skovorodkin, Federico Soria, Seppo Vainio, Shaokai Zheng
Bladder catheters and urinary stents share indications (urinary drainage), materials, and inherent problems (infection, encrustation, biofilms, blockages, etc.). Research on either is therefore relevant to the other. With bladder catheters, blockage through encrustation is a frequent problem. It often results from urine infection with urease producing organisms, predominantly Proteus mirabilis. Urease generates ammonium which increases urinary pH, leading to struvite and apatite precipitation which form a crystalline biofilm that encrusts and blocks the urinary catheter. To reduce this problem, sensors have been incorporated in catheters to warn early of pH changes indicating impending blockage. To date, such pH sensors are mainly visual. A color strip indicated a risk of blockage 19 days before the actual blockage in early human trials [52]. Another indicator is a ‘trigger’ layer, usually EUDRAGIT®S 100, onto a hydrogel layer encapsulating a pH reporter or antibacterial agent. Upon elevation of urinary pH, the upper layer dissolves, triggering the release of a pH indicator such as carboxyfluorescein or bacteriophages. Both methods were tested in an in vitro bladder model. There was a 12 h advanced warning of blockage, and a 13 to 26 h advanced warning of delayed catheter blockage, respectively [53,54]. Whereas catheters have an extracorporeal part that can carry those visual indicators, stents are entirely intracorporeal. However, in the age of nano-chip technology, it seems entirely possible to fix a microsensor at one or both ends of a stent transmitting pH values or intrarenal pressure data indicating stent obstruction wirelessly.
Developing a subjective instrument for laparoscopic surgical workload in a high fidelity simulator using the NASA-TLX and SURG-TLX
Published in IISE Transactions on Healthcare Systems Engineering, 2020
Jiahui Ma, Bethany Lowndes, Kristin Chrouser, Susan Hallbeck, Bernadette McCrory
Participants with formal medical education were recruited at a large, midwestern teaching hospital. Participants consisted of 23 medical students and 2 residents. Each participant completed two simulated laparoscopic surgery tasks (peg transfer task and clock transfer task) (see Fig. 2) using four different methods (order randomized) including conventional laparoscopy (CL), unaltered LESS allowing for intracorporeal crossing of instruments (UL), physically correct LESS with extracorporeal crossing of hands (PL) and visually altered LESS with transposed visual display (VL) (see Fig. 3) (Abdelrahman et al., 2018; Brown-Clerk et al., 2011; Hallbeck et al., 2017; Lowndes et al., 2016; McCrory et al., 2012, McCrory et al., 2013). The peg transfer task is one of the stimulated skills selected from the Fundamentals of Laparoscopic Surgery (FLS), which requires participants to transfer objects from the non-dominant hand to dominant hand. The clock transfer task is a novel stimulated task developed specially for this assessment, which requires participants to transfer objects in a clockwise direction. The clock transfer task was designed to be more difficult than the peg transfer task due to its spatial orientation requirement. CL is the method used for conventional laparoscopy surgery. UL, PL and VL are three methods modified from CL for performing LESS with instruments entering the body cavity through a single port (Lowndes et al., 2016). Compared with CL, UL increases the difficulty of the procedure due to the reduced insertion points including the left-right reversal of the instruments on the screen caused by intracorporeal instrument crossing (Lowndes et al., 2016). PL is an alternative method for UL to resolve the left-right reversal by also crossing both hands extracorporeally, but potentially increases physical difficulty due to an unnatural hand posture (Ishikawa et al., 2009). VL is an experimental method to modify UL to resolve the left-right reversal by transposing the visual display (Lowndes et al., 2016).