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Faragher SR et al, 2016: In Vitro Assessment of Three Clinical Lithotripters Employing Different Shock Wave Generators.

Faragher SR, Cleveland RO, Kumar S, Wiseman OJ, Turney BW.
Oxford Stone Group, Nuffield Department of Surgical Sciences, The Churchill Hospital , Oxford, United Kingdom.
Institute of Biomedical Engineering, University of Oxford, Oxford, United Kingdom.
Urology Department, Royal Berkshire NHS Foundation Trust, Reading, United Kingdom.
Department of Urology, Addenbrooke's Hospital, Cambridge, United Kingdom.

Abstract

OBJECTIVE: To test the hypothesis that shock wave lithotripsy machines vary in their ability to fragment standardized artificial urinary calculi.
MATERIALS AND METHODS: An in vitro test configuration was used to fragment synthetic U-30 Gypsum (U.S. Gypsum, Chicago, IL) stones (mean length 7.1 ± 0.2 mm, mean diameter 6.5 ± 0.07 mm, mean mass 299 ± 16 mg) using the Sonolith i-sys (EDAP TMS, Vaulx-en-Velin, France), Modulith SLX F2 (Storz Medical AG, Tägerwilen, Switzerland), and Piezolith 3000 (Richard Wolf GmbH, Knittlingen, Germany) lithotripters. Gypsum stones were placed at the nominal focus and treated with 250, 500, or 1000 shocks. The residual mass following passage through a 2-mm wire mesh was measured and compared using ANOVA and the Tukey-Kramer HSD test.
RESULTS: There was no statistically significant difference between the Modulith SLX F2 and Piezolith 3000 lithotripters for 250 and 1000 shock treatments (p = 0.34 and 0.31, respectively). The Piezolith 3000 demonstrated the most favorable stone mass reduction for 500 shock treatments (187.4 ± 45.2 mg). The Sonolith i-sys was found to be significantly less effective than the other lithotripters for all shockwave conditions. Furthermore, performance of the Sonolith i-sys decreased beyond a threshold generator electrode age of 6000 shocks.
CONCLUSIONS: This in vitro study found considerable variability in the ability of lithotripters to fragment synthetic urinary calculi. Synthetic stones were employed to provide a repeatable means of assessing variability in fragmentation efficiency of lithotripters. The Modulith SLX F2 and Piezolith 3000 are broadly equal and resulted in greater fragmentation efficiencies than the Sonolith i-sys. The performance of the Sonolith i-sys deteriorates at 6000 shocks, before the specified lifetime of 20,000 shocks.

J Endourol. 2016 Feb 26. [Epub ahead of print]

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Hans-Göran Tiselius on Wednesday, 25 May 2016 07:49

In this in vitro assessment of stone fragmentation with three different lithotripters: Sonolith i-sys (electro-conductive), Modulith SLX-F2 (electromagnetic) and Piezolith 3000 (piezoelectric) the experiments were carried out with artificial stones exposed to shockwaves in a standardized way. Fluoroscopic focusing was used for the first two and ultrasound for the third device.

There are two observations that need to be commented. Firstly that both electromagnetic and piezoelectric technique resulted in better disintegration than the electro-conductive method. Secondly that the life-time of the electro-conductive electrode was much shorter than that claimed by the manufacturer.

Despite the in vitro character of this study it is interesting to examine how well these data corresponds to clinical observations expressed in terms of stone treatment index (STI) [1]. My intention therefore was to collect treatment data from my own experience with Modolith SLX-F2 and three recent publications in which Sonolith i–sys [2] and Piezolith 3000 [3,4,5] were used. This comparison is of course only very approximate because all data for STI-calculation were not found in any of the reports [2-5] and accordingly several assumptions were necessary. Most problematic is that the result in different publications is presented in so different ways. Only stone disintegration and not stone-free rates were considered to be comparable with the results from the in vitro study.

http://storzmedical.com/images/blog/Faragher_SR.png

* Obtained as an average for stones in the kidney and ureter
** Calculated for both imaging techniques
*** Adults only

Although the STI values are very approximate and needs to be interpreted with great caution it is nevertheless of importance to observe the difference between clinical and experimental results.

References
1. Tiselius HG, Ringdén I.
Stone treatment index: a mathematical summary of the procedure for removal of stones from the urinary tract.
J Endourol. 2007 Nov;21(11):1261-9.
2. Abid N, Ravier E, Promeyrat X, Codas R, Fehri HF, Crouzet S, Martin X.
Decreased Radiation Exposure and Increased Efficacy in Extracorporeal Lithotripsy Using a New Ultrasound Stone Locking System.
J Endourol. 2015 Nov;29(11):1263-9. doi: 10.1089/end.2015.0175. Epub 2015 Aug 21.
3. Goktas C, Akca O, Horuz R, Gokhan O, Albayrak S, Sarica K.
SWL in lower calyceal calculi: evaluation of the treatment results in children and adults.
Urology. 2011 Dec;78(6):1402-6. doi: 10.1016/j.urology.2011.08.005. Epub 2011 Oct 2
4. Wang R, Faerber GJ, Roberts WW, Morris DS, Wolf JS Jr.
Single-center North American experience with wolf Piezolith 3000 in management of urinary calculi.
Urology. 2009 May;73(5):958-63. doi: 10.1016/j.urology.2008.06.013. Epub 2009 Mar 17.

5. Hwang I, Jung SI, Kim KH, Hwang EC, Yu HS, Kim SO, Kang TW, Kwon DD, Park K.
Factors influencing the failure of extracorporeal shock wave lithotripsy with Piezolith 3000 in the management of solitary ureteral stone. Urolithiasis. 2014 Jun;42(3):263-7. doi: 10.1007/s00240-014-0641-8. Epub 2014 Feb

In this in vitro assessment of stone fragmentation with three different lithotripters: Sonolith i-sys (electro-conductive), Modulith SLX-F2 (electromagnetic) and Piezolith 3000 (piezoelectric) the experiments were carried out with artificial stones exposed to shockwaves in a standardized way. Fluoroscopic focusing was used for the first two and ultrasound for the third device. There are two observations that need to be commented. Firstly that both electromagnetic and piezoelectric technique resulted in better disintegration than the electro-conductive method. Secondly that the life-time of the electro-conductive electrode was much shorter than that claimed by the manufacturer. Despite the in vitro character of this study it is interesting to examine how well these data corresponds to clinical observations expressed in terms of stone treatment index (STI) [1]. My intention therefore was to collect treatment data from my own experience with Modolith SLX-F2 and three recent publications in which Sonolith i–sys [2] and Piezolith 3000 [3,4,5] were used. This comparison is of course only very approximate because all data for STI-calculation were not found in any of the reports [2-5] and accordingly several assumptions were necessary. Most problematic is that the result in different publications is presented in so different ways. Only stone disintegration and not stone-free rates were considered to be comparable with the results from the in vitro study. [img]http://storzmedical.com/images/blog/Faragher_SR.png[/img] * Obtained as an average for stones in the kidney and ureter ** Calculated for both imaging techniques *** Adults only Although the STI values are very approximate and needs to be interpreted with great caution it is nevertheless of importance to observe the difference between clinical and experimental results. References 1. Tiselius HG, Ringdén I. Stone treatment index: a mathematical summary of the procedure for removal of stones from the urinary tract. J Endourol. 2007 Nov;21(11):1261-9. 2. Abid N, Ravier E, Promeyrat X, Codas R, Fehri HF, Crouzet S, Martin X. Decreased Radiation Exposure and Increased Efficacy in Extracorporeal Lithotripsy Using a New Ultrasound Stone Locking System. J Endourol. 2015 Nov;29(11):1263-9. doi: 10.1089/end.2015.0175. Epub 2015 Aug 21. 3. Goktas C, Akca O, Horuz R, Gokhan O, Albayrak S, Sarica K. SWL in lower calyceal calculi: evaluation of the treatment results in children and adults. Urology. 2011 Dec;78(6):1402-6. doi: 10.1016/j.urology.2011.08.005. Epub 2011 Oct 2 4. Wang R, Faerber GJ, Roberts WW, Morris DS, Wolf JS Jr. Single-center North American experience with wolf Piezolith 3000 in management of urinary calculi. Urology. 2009 May;73(5):958-63. doi: 10.1016/j.urology.2008.06.013. Epub 2009 Mar 17. 5. Hwang I, Jung SI, Kim KH, Hwang EC, Yu HS, Kim SO, Kang TW, Kwon DD, Park K. Factors influencing the failure of extracorporeal shock wave lithotripsy with Piezolith 3000 in the management of solitary ureteral stone. Urolithiasis. 2014 Jun;42(3):263-7. doi: 10.1007/s00240-014-0641-8. Epub 2014 Feb
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