MP41-02 INFERENCE OF SHOCK RATE AND POWER ON EFFECTIVE AND EFFICIENT KIDNEY STONE FRAGMENTATION WITH EXTRACORPOREAL SHOCKWAVE LITHOTRIPSY (ESWL)

Abstract

You have accessJournal of UrologyStone Disease: Medical Therapy1 Apr 2015MP41-02 INFERENCE OF SHOCK RATE AND POWER ON EFFECTIVE AND EFFICIENT KIDNEY STONE FRAGMENTATION WITH EXTRACORPOREAL SHOCKWAVE LITHOTRIPSY (ESWL) James Hayes, Ray Kirk, and Ann Richardson James HayesJames Hayes More articles by this author , Ray KirkRay Kirk More articles by this author , and Ann RichardsonAnn Richardson More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2015.02.1630AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES There are pressures to reduce total shock numbers to reduce renal and other organ damage. There is also a need to improve the efficiency of ESWL. This in vitro study looks at the influence of shock rate and power on stone fragmentation. Can both of these outcomes be achieved through the adequate understanding of how and why shock waves produce effects on stone and tissue? METHODS A simulation silicone model for the kidney in vitro was established to measure the efficiency of various combinations of shock rate and power. Each combination was tested individually. The model kidney was set up underwater to avoid any artifacts due to gas. A mock kidney stone was inserted in a usual calyx structure and using the ESWL machine the stone was fragmented to completion ≤ 4mm. 396 mock kidney stones were used in total. RESULTS For the studies investigating the effect that the shock rate has on stone fragmentation, the most effective rate (least number of shocks for complete stone fragmentation) was 60 shocks per minute (spm) and the most efficient (shortest time to complete stone fragmentation) was 100 spm. The most effective and efficient power was 17.8kV across all shock rates tested, although it should be noted that although the stone fragmentation was most effective at the higher powers and there was a near linear graph from low (12kV) to high (17.8kV), the graph leveled off after 16kV. The highest power level (17.8kV), used clinically, resulted in the most efficient fragmentation, as expected, unless rate is considered in addition to power, in which case at the slower rate of 60 shocks a minute 17.8kV power is the most destructive. This is followed by a shock rate of 100 at 17.8kV power and then 60 spm at 16kV power followed by 60 spm at 16.9kV power. CONCLUSIONS Using a rate of 60 spm enhances fragmentation at all power levels used, not only with regards to the number of shocks needed, but from observations, the stone fragments appeared smaller and more dust-like than the larger sand-like particles produced at faster rates. This is likely to lead to enhanced clearance as the smaller fragments can pass more easily in the urine. This is consistent with the literature. The results from the power experiments are clear. Using a shock rate of 60 a minute appears to offer the most benefits, especially as lower powers can be used for the same or similar results. Implications for current clinical practice will be discussed. © 2015 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 193Issue 4SApril 2015Page: e500 Advertisement Copyright & Permissions© 2015 by American Urological Association Education and Research, Inc.MetricsAuthor Information James Hayes More articles by this author Ray Kirk More articles by this author Ann Richardson More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...