SWL literature
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Rabah DM et al, 2016: Comparison of escalating, constant, and reduction energy output in ESWL for renal stones: multi-arm prospective randomized study.

Rabah DM, Mabrouki MS, Farhat KH, Seida MA, Arafa MA, Talic RF.
Surgery Department, Cancer Research Chair, College of Medicine, King Saud University, Riyadh, Saudi Arabia.
Sharjah University Hospital, Sharjah, United Arab Emirates.

Abstract

This study was designed to find out the optimized energy delivery strategy in Shock Wave Lithotripsy (SWL) that yield to the best stone-free rate (SFR). In this clinical trial, 150 consecutive patients were randomized into three groups: (a) Dose escalation, 1500 SW at 18 kV, followed by 1500 SW at 20 kV then 1500 SW at 22 kV. (b) Constant dose, 4500 SW at 20 kV. All patients undergo plain X-ray film of the urinary tract at day 1, 14, and 90 to assess stone-free rate (SFR) which was defined as no stones or painless fragments less than 4 mm. (c) Dose reduction, 1500 SW at 22 kV, followed by 1500 SW at 20 kV and then 1500 SW at 18 kV. The three treatment groups were comparable in terms of age, sex, stone size and distribution of the kidneys, and the need for Double J stent use. On day 90, the SFR achieved was 82, 90, and 84 % in the escalating, constant, and reduction energy groups, respectively. However, this rate was not statistically significant (x 2 = 1.38, p level = 0.28). At a slow rate of 60 shocks, there was no difference in stone-free rate between different voltages at 1, 14, and 90 days. Our randomized clinical trial showed no statistically significant difference in SFR between the three groups while using the slow SWL rate. Our trial is the first randomized trial comparing the three strategies. As such, a dose adjustment strategy while delivering SWL in slow rate was not recommended.

Urolithiasis. 2016 Sep 29. [Epub ahead of print]

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Comments 1

Hans-Göran Tiselius on Friday, 16 June 2017 11:33

SWL can be carried out in many different ways. The frequency of shockwave administration that usually is applied is 30, 60, 90 and 120 /minute (0.5, 1.0, 1.5 and 2 Hz). The total number of shockwaves given might vary, usually in the range of 2000 – 5000 per session. Experimental as well as clinical studies have indicated that introduction of a pause in the beginning of the session might be of advantage by causing vasoconstriction and reduced risk of bleeding complications. The different methods can be combined in different ways and the result will probably differ between lithotripters and patients. The value of different treatment protocols can be evaluated both in terms of stone disintegration (stone-free rate) and tissue effects. In this report (with Siemens Lithostar) three different protocols were used for applying shockwave energy.

http://storzmedical.com/images/blog/Rabah_DM.jpg

The numerically better result after 90 days with protocol B might be an effect of the greater total energy given to these patients.

The shockwave frequency was 1 Hz and no pause was introduced in the protocol.

Ultrasound examination did not disclose any hematoma.

The bottom-line of this report is that whereas variation in energy levels in an escalated, constant or reduced model cannot be recommended in terms of stone disintegration the effect on renal tissue has not been studied. Moreover, it is of note that only 6.6% of the patients were treated with intravenous sedation, the others with general, spinal or epidural anaesthesia. In patients treated with only analgesics and sedatives it might be necessary to stepwise increase the energy (escalating, ramping) in order to get patents’ adaptation to the shockwave delivery. According to the results in this report such an approach will unlikely result in an inferior outcome.

SWL can be carried out in many different ways. The frequency of shockwave administration that usually is applied is 30, 60, 90 and 120 /minute (0.5, 1.0, 1.5 and 2 Hz). The total number of shockwaves given might vary, usually in the range of 2000 – 5000 per session. Experimental as well as clinical studies have indicated that introduction of a pause in the beginning of the session might be of advantage by causing vasoconstriction and reduced risk of bleeding complications. The different methods can be combined in different ways and the result will probably differ between lithotripters and patients. The value of different treatment protocols can be evaluated both in terms of stone disintegration (stone-free rate) and tissue effects. In this report (with Siemens Lithostar) three different protocols were used for applying shockwave energy. [img]http://storzmedical.com/images/blog/Rabah_DM.jpg[/img] The numerically better result after 90 days with protocol B might be an effect of the greater total energy given to these patients. The shockwave frequency was 1 Hz and no pause was introduced in the protocol. Ultrasound examination did not disclose any hematoma. The bottom-line of this report is that whereas variation in energy levels in an escalated, constant or reduced model cannot be recommended in terms of stone disintegration the effect on renal tissue has not been studied. Moreover, it is of note that only 6.6% of the patients were treated with intravenous sedation, the others with general, spinal or epidural anaesthesia. In patients treated with only analgesics and sedatives it might be necessary to stepwise increase the energy (escalating, ramping) in order to get patents’ adaptation to the shockwave delivery. According to the results in this report such an approach will unlikely result in an inferior outcome.
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