Comparison of escalating, constant, and reduction energy output in ESWL for renal stones: multi-arm prospective randomized study

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 = 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.

Outcomes of extracorporeal shock wave lithotripsy for ureteral stones according to ESWL intensity

“…Thus, the "ramping technique" of gradually escalating intensity was introduced. It was hypothesized that this technique strengthens the formation of cavitation bubbles and recompenses for the screening effect (11,14). This method prepares the patient to adapt to the sense of SWL.…”

“…A shock wave frequency of 60-90 shock waves/min improves the stone-free rate (SFR), and tissue damage decreases with a low shock wave frequency (5,6). Recent studies recommend increasing the power step-by-step, as this ramping technique improves stone fragmentation and reduces renal injury during ESWL (7)(8)(9)(10)(11). Additionally, medical expulsive therapy (MET) is efficient for relieving pain and the passage of a stone (12); however, the types of shock waves generated by other methods are not successful (9).…”

Automated Generation of Personalized Shock Wave Lithotripsy Protocols: Treatment Planning Using Deep Learning

“…A plan precisely specifies step-by-step power levels, shock rates, and number of shocks. Each treatment step has a single power level, a constant shock rate, and shocks usually between 500-2500 [23][24][25][26][27][28]. Physicians are obliged to design plans that both deliver sufficient energy for breaking stones and minimize damage to body tissues.…”

“…The low-energy pretreatment allows for better pain management, thus preventing movement and subsequent decoupling of the shock head [34]. Clinical trials support that stepwise voltage ramping is associated with less tissue damage compared with a fixed maximal voltage protocol [23,25,26,35].…”

“…The optimal energy delivery strategy remains controversial. In vitro and in vivo studies suggest that the strategy of ramping up shock wave energy is beneficial to improve fragmentation and stone clearance and limit renal damage, but clinical results are discordant [6,23]. In the current planning process, physicians adopt a trial-and-error approach to tune treatment plans.…”