Optimising an escalating shockwave amplitude treatment strategy to protect the kidney from injury during shockwave lithotripsy
ABSTRACT Study Type - Therapy (case series) Level of Evidence 4 What's known on the subject? and What does the study add? Animal studies have shown that one approach to reduce SWL-induced renal injury is to pause treatment for 3-4 min early in the SWL-treatment protocol. However, there is typically no pause in treatment during clinical lithotripsy. We show in a porcine model that a pause in SWL treatment is unnecessary to achieve a reduction in renal injury if treatment is begun at a low power setting that generates low-amplitude SWs, and given continuously for ≈4 min before applying higher-amplitude SWs. OBJECTIVE: • To test the idea that a pause (≈3 min) in the delivery of shockwaves (SWs) soon after the initiation of SW lithotripsy (SWL) is unnecessary for achieving a reduction in renal injury, if treatment is begun at a low power setting that generates low-amplitude SWs. MATERIALS AND METHODS: • Anaesthetised female pigs were assigned to one of three SWL treatment protocols that did not involve a pause in SW delivery of >10 s (2000 SWs at 24 kV; 100 SWs at 12 kV +≈10-s pause + 2000 SWs at 24 kV; 500 SWs at 12 kV +≈10-s pause + 2000 SWs at 24 kV). • All SWs were delivered at 120 SWs/min using an unmodified Dornier HM3 lithotripter. • Renal function was measured before and after SWL. • The kidneys were then processed for quantification of the SWL-induced haemorrhagic lesion. Values for lesion size were compared to previous data collected from pigs in which treatment included a 3-min pause in SW delivery. RESULTS: • All SWL treatment protocols produced a similar degree of vasoconstriction (23-41% reduction in glomerular filtration rate and effective renal plasma flow) in the SW-treated kidney. • The mean renal lesion in pigs treated with 100 low-amplitude SWs delivered before the main dose of 2000 high-amplitude SWs (2.27% functional renal volume [FRV]) was statistically similar to that measured for pigs treated with 2000 SWs all at high-amplitude (3.29% FRV). • However, pigs treated with 500 low-amplitude SWs before the main SW dose had a significantly smaller lesion (0.44% FRV) that was comparable with the lesion in pigs from a previous study in which there was a 3-min pause in treatment separating a smaller initial dose of 100 low-amplitude SWs from the main dose of 2000 high-amplitude SWs (0.46% FRV). The time between the initiation of the low - and high-amplitude SWs was ≈4 min for these latter two groups compared with ≈1 min when there was negligible pause after the initial 100 low-amplitude SWs in the protocol. CONCLUSIONS: • Pig kidneys treated by SWL using a two-step low-to-high power ramping protocol were protected from injury with negligible pause between steps, provided the time between the initiation of low-amplitude SWs and switching to high-amplitude SWs was ≈4 min. • Comparison with results from previous studies shows that protection can be achieved using various step-wise treatment scenarios in which either the initial dose of SWs is delivered at low-amplitude for ≈4 min, or there is a definitive pause before resuming SW treatment at higher amplitude. • Thus, we conclude that renal protection can be achieved without instituting a pause in SWL treatment. It remains prudent to consider that renal protection depends on the acoustic and temporal properties of SWs administered at the beginning stages of a SWL ramping protocol, and that this may differ according to the lithotripter being used.
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ABSTRACT: Stone disease remains a prevalent problem and an important aspect in the urologist’s practice. Flexible ureterorenoscopy (F-URS) is gaining popularity and accessibility over the last two decades for the treatment of ureteral and renal stones. The smaller diameter, durability and maneuverability of the ureteroscope continues to evolve and contribute to the increased effectiveness of this treatment. Studies demonstrating the feasibility and safety of F-URS even in stones larger than 2 cm illustrate the versatility of this technique and the importance of being comfortable with all the equipment available in order to perform a successful surgery. F-URS is presently a treatment option for stones of all sizes and locations in the ureter. In this chapter, we review the instrumentation available, the methods to navigate the ureter and potential complications of F-URS. The specifics regarding ureteral stents, guidewires, baskets, laser lithotripsy and other devices are discussed in other chapters. As proximal ureteral stones can sometimes be relocated or moved into the renal pelvis via retropulsion, we will also touch upon the use of flexible ureteroscopy in the treatment of renal stones in this chapter as wellUreteral Stone Management A Practical Approach, Edited by Sutchin R. Patel, Stephen Y. Nakada, 01/2015: pages 107-126; Springer International Publishing., ISBN: 978-3-319-08792-4
Article: Office-based stone management.[Show abstract] [Hide abstract]
ABSTRACT: As hospital resources are becoming strained, ambulatory surgical centers and day hospitals are being increasingly utilized. For the urologist, a working knowledge of local anesthetics and conscious sedation protocols are important, as many surgical kidney-stone procedures can be performed without general anesthetic. With any anesthesia, the key goal is to maximize patient comfort while minimizing respiratory depression and avoiding prolonged sedation. When using these medications, a working knowledge of emergency reversal, ventilation (bag mask/laryngeal mask airway/intubation), and cardiopulmonary resuscitation is recommended.Urologic Clinics of North America 11/2013; 40(4):481-95. DOI:10.1016/j.ucl.2013.07.007 · 1.35 Impact Factor
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ABSTRACT: To evaluate regional differences in adaptation of best practice recommendations for extracorporeal shock wave lithotripsy (SWL) across 4 distinct geographic regions. A retrospective study was performed using a prospective database maintained by a mobile lithotripsy provider (ForTec Medical, Streetsboro, OH). SWL cases performed in Ohio, Northern Illinois/Southern Wisconsin, Florida, and New York were included. Treatment parameters evaluated included treatment rate, use of a power ramp-up protocol, use of a pretreatment pause after the initial 100 shocks, ancillary procedures, and need for retreatment. Regional and physician-specific patterns were examined. Statistical analyses using chi-square and analysis of variance were performed with a significance of P <.05. Data from 2240 SWL procedures were included in the study. Overall adaptation of power ramp-up protocols and treatment rates were high (93% and 93%), whereas use of pause was lower (75%, P <.001). Retreatment rates were low (4.3%), although ancillary procedures were performed in 34% of patients, and 8.3% of patients received stents for stones <1 cm. Regional differences were present in all parameters: Florida physicians used power ramp-up less (83%, P <.001) but had good use of pretreatment pause (98%, P <.001), both Wisconsin/Illinois and New York were less likely to use slow rate (87% and 84%, respectively, P <.001). The recommendations for slower shock wave rates and power ramp protocols have reached high penetration in urologic practices; however, the more recent recommendation for a pause after the initial 100 shocks has been less uniformly implemented. Inconsistencies in regional adaptation of best practices may identify opportunities for further education.Urology 05/2014; 83(5):1060-4. DOI:10.1016/j.urology.2014.01.017 · 2.13 Impact Factor