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Jagtap J et al, 2014: Evolution of SWL technique: A 25 year single centre experience of over 5000 patients.

Jagtap J, Mishra S, Bhattu A, Ganpule A, Sabnis R, Desai M
Department of Urology, Muljibhai Patel Urological Hospital, Nadiad, India

 

Abstract

OBJECTIVES: To assess the impact of various treatment optimizing strategies in SWL utilized at a single centre over the period of last 25 years. PATIENTS AND METHODS: 5017 patients between 1989 to 2013 were reviewed and divided into groups A, B,C and D during the treatment periods of 1989-1994 (n=1561),1995-2000(n=1741), 2001-2006(n=1039) and 2007-2013(n=676), respectively. Sonolith 3000 (A & B) and Dornier compact delta lithotripters (C & D) were used. Refinements included frequent relocalisation, limiting maximum shocks and booster therapy in group B and Hounsfield unit estimation, power ramping and improved coupling in group D. Parameters reviewed were annual
SWL utilization, stone and treatment data, retreatment, auxiliary procedures, complications and stone free rates (SFR). RESULTS: SFR with Dornier compact delta was significantly higher than Sonolith 3000 (p<0.0001). The SFR improved significantly from 77.58%,81.28%,82.58% to 88.02% in groups A,B,C,D respectively (p<0.0001).There was a concomitant decrease in repeat SWL (retreatment rate) and complication rates as well. (48.7%, 33.4%, 15.8%, 10.1%, and 8%, 6.4%, 4.9%, 1.6%, p<0.0001 respectively). This led to a rise in Efficiency quotient (EQ) from 50.41, 58.94, 68.78 to 77.06, p=0.0006).The auxiliary procedure rates were similar in all groups (p=0.62). CONCLUSION: In conclusion,
improvement in EQ along with a concomitant decrease in complication rate can be achieved with optimum patient selection and employment of various treatment optimizing strategies.

BJU Int. 2014 May 13. doi: 10.1111/bju.12808. [Epub ahead of print]

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Comments 1

Hans-Göran Tiselius on Tuesday, 16 September 2014 07:23

Despite its retrospective approach this article is highly interesting because it summarizes the authors´ experience with SWL during a period of 24 years (!) with approximately 5000 patients treated. Two different lithotripters were used: Sonolith 300 and Dornier Compact Delta. During the 24 years the lithotripter and routines were changed (four periods A,B,C, and D). Important to note is that the authors consider operator skill and experience necessary for adequate treatment results. This is probably one factor in explanation of the generally high stone free rates achieved during all four periods. Improved principles of treatment and changes in criteria for patient selection resulted in decreased re-treatment rates and increased stone-free rates.

Some notes on the methodology and patient selection are worthwhile to mention: The current principles comprise ramping, a pause after 100 shockwaves, a maximum number of 1500 shockwaves per session, a shockwave frequency of 60 and a focus check every 200 shockwaves!

Given the authors experience and interest in endoscopic procedures, only proximal ureteral stones were included. The authors presented their achievements in terms of EQ, but in order to also take into consideration the stone burden and complications I have below calculated approximate STI (Stone Treatment Index; [1]). Thereby it was assumed that the stone width was 60% of the length, the hardness index 1.18 and the BMI-ratio 1.0.

Minor differences are observed but the overall result during all four periods is unusually good. The improvement is a result not only of altered patient selection, but also better SWL technique.
Despite the relatively small differences in stone surface area (SA) between periods B, C and D it is of interest to learn that a maximum number of 1500 shockwaves nevertheless resulted in a high EQ and STI.

Link: http://www.smag-global.com/images/blog/jagtab2014.jpg

Reference
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 21:1261-1269.

Despite its retrospective approach this article is highly interesting because it summarizes the authors´ experience with SWL during a period of 24 years (!) with approximately 5000 patients treated. Two different lithotripters were used: Sonolith 300 and Dornier Compact Delta. During the 24 years the lithotripter and routines were changed (four periods A,B,C, and D). Important to note is that the authors consider operator skill and experience necessary for adequate treatment results. This is probably one factor in explanation of the generally high stone free rates achieved during all four periods. Improved principles of treatment and changes in criteria for patient selection resulted in decreased re-treatment rates and increased stone-free rates. Some notes on the methodology and patient selection are worthwhile to mention: The current principles comprise ramping, a pause after 100 shockwaves, a maximum number of 1500 shockwaves per session, a shockwave frequency of 60 and a focus check every 200 shockwaves! Given the authors experience and interest in endoscopic procedures, only proximal ureteral stones were included. The authors presented their achievements in terms of EQ, but in order to also take into consideration the stone burden and complications I have below calculated approximate STI (Stone Treatment Index; [1]). Thereby it was assumed that the stone width was 60% of the length, the hardness index 1.18 and the BMI-ratio 1.0. Minor differences are observed but the overall result during all four periods is unusually good. The improvement is a result not only of altered patient selection, but also better SWL technique. Despite the relatively small differences in stone surface area (SA) between periods B, C and D it is of interest to learn that a maximum number of 1500 shockwaves nevertheless resulted in a high EQ and STI. Link: http://www.smag-global.com/images/blog/jagtab2014.jpg Reference 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 21:1261-1269.
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